CN114825952A - Converter control method and device and vehicle-mounted power supply - Google Patents
Converter control method and device and vehicle-mounted power supplyDownload PDFInfo
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- CN114825952A CN114825952ACN202210261973.5ACN202210261973ACN114825952ACN 114825952 ACN114825952 ACN 114825952ACN 202210261973 ACN202210261973 ACN 202210261973ACN 114825952 ACN114825952 ACN 114825952A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of DC power input into DC power output
- H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
- H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
- H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
- H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33592—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
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Abstract
Description
Technical Field
The invention relates to the technical field of power conversion, in particular to a converter control method and device and a vehicle-mounted power supply.
Background
The magnetic integrated converter is an integrated device in which an OBC (On-board Charger) and a DC/DC (direct current/direct current) converter share one transformer, and has the characteristics of miniaturization and light weight, so that the occupation of a vehicle-mounted power supply to a vehicle space can be reduced, and the magnetic integrated converter has a wide application prospect in new energy automobiles.
As shown in fig. 1, the three-port structure of the magnetic integrated converter includes a dc bus side circuit, a transformer, a high voltage side circuit, and a low voltage side circuit, the dc bus side circuit is electrically connected to the primary winding of the transformer, the high voltage side circuit is electrically connected to the first secondary winding of the transformer, and the low voltage side circuit is electrically connected to the second secondary winding of the transformer. When the magnetic integrated converter works in a DC/DC mode, energy flows from a high-voltage side circuit to a direct-current bus side circuit and then flows from the direct-current bus side circuit to a low-voltage side circuit to supply power to a low-voltage load in the low-voltage side circuit, wherein in order to meet the power supply power of the low-voltage load, switching tubes in the high-voltage side circuit and the direct-current bus side circuit need to be controlled, but energy loss caused by the control process influences energy transfer efficiency (DC/DC efficiency).
At present, the following methods are commonly adopted to reduce energy loss and improve energy transfer efficiency: (1) the loss of switching on and switching off the switch tube in the converter is reduced by soft switching the switch tube, but the condition that the switch tube cannot realize soft switching easily occurs when the transmission power in a DC/DC mode is small, and the effectiveness is poor; (2) the switching tube with smaller conduction internal resistance and/or the transformer with smaller copper loss and iron core loss are adopted, but the cost is higher in the method.
Disclosure of Invention
The invention solves the problem of how to improve the energy transfer efficiency when the converter works in a DC/DC mode and ensure the power supply power of a low-voltage load.
In order to solve the problems, the invention provides a converter control method, a converter control device and a vehicle-mounted power supply.
In a first aspect, the present invention provides a converter control method, including:
when the converter is in a DC/DC mode, acquiring battery voltages at two ends of the high-voltage battery;
determining initial values of bus voltages at two ends of a bus capacitor under an uncontrolled rectification state according to the battery voltage, and determining lower values of the bus voltages at two ends of the bus capacitor according to expected values of output voltages of low-voltage loads;
determining a bus voltage expected value according to the bus voltage initial value and the bus voltage lower limit value based on a preset rule;
and regulating the bus voltage at two ends of the bus capacitor according to the expected bus voltage value.
Optionally, the determining, according to the battery voltage, an initial value of a bus voltage across a bus capacitor in an uncontrolled rectification state includes:
based on a bus voltage calculation model, determining an initial value of the bus voltage according to the battery voltage, and a predetermined number of turns of a primary winding, a predetermined number of turns of a first secondary winding and a predetermined first correction parameter;
wherein the first correction parameter is associated with loss voltages in the high-voltage side circuit and the direct-current bus side circuit in the uncontrolled rectifying state.
Optionally, the uncontrolled rectification state indicates that energy flows only from the high-voltage side circuit to the dc bus side circuit, and a phase difference between the primary side full bridge circuit and the secondary side full bridge circuit is 0.
Optionally, the determining a lower limit value of the bus voltage across the bus capacitor according to the expected output voltage of the low-voltage load includes:
and determining the lower limit value of the bus voltage according to the expected output voltage value, the number of primary winding turns, the number of second secondary winding turns and a second correction parameter, wherein the second correction parameter is related to loss voltages in the direct current bus side circuit and the low voltage side circuit.
Optionally, the first correction parameter and the second correction parameter are determined according to a voltage equivalent transformation method and/or an experimental data fitting method.
Optionally, the determining, based on a preset rule, a bus voltage expected value according to the bus voltage initial value and the bus voltage lower limit value includes: and determining the maximum value of the initial bus voltage value and the lower bus voltage limit value as the expected bus voltage value.
Optionally, the adjusting the bus voltage across the bus capacitor according to the desired bus voltage value includes:
acquiring actual bus voltage values at two ends of the bus capacitor, and determining a difference value between the expected bus voltage value and the actual bus voltage value;
and carrying out voltage loop PI control according to the difference value, and adjusting the phase difference between the primary side full-bridge circuit and the secondary side full-bridge circuit so as to adjust the bus voltage.
Optionally, after the bus voltage across the bus capacitor is adjusted according to the desired bus voltage value, the method further includes: and when the bus voltage reaches the bus voltage expected value, controlling the switch tube in the low-voltage side circuit to be conducted.
In a second aspect, the present invention provides an inverter control device comprising:
the acquisition module is used for acquiring the battery voltage at two ends of the high-voltage battery when the converter is in a DC/DC mode;
the processing module is used for determining bus voltage initial values at two ends of the bus capacitor in an uncontrolled rectification state according to the battery voltage and determining bus voltage lower limit values at two ends of the bus capacitor according to an output voltage expected value of a low-voltage load; based on a preset rule, determining a bus voltage expected value according to the bus voltage initial value and the bus voltage lower limit value;
and the control module is used for adjusting the bus voltage at two ends of the bus capacitor according to the expected bus voltage value.
In a third aspect, the invention provides a vehicle-mounted power supply, which comprises an inverter and electronic equipment, wherein the electronic equipment is electrically connected with each switching tube in the inverter respectively;
the electronic device comprises a memory and a processor; the memory for storing a computer program; the processor is configured to implement the converter control method according to any one of the first aspect when the computer program is executed.
The converter control method, the converter control device and the vehicle-mounted power supply have the beneficial effects that: whether the converter is in the DC/DC mode or not can be judged in advance, and if yes, the battery voltage at two ends of the high-voltage battery is obtained. The method comprises the steps that a bus voltage initial value at two ends of a bus capacitor in an uncontrolled rectification state is calculated according to the voltage of a battery, a switching tube in a converter is not subjected to phase shift control in the uncontrolled rectification state, the current in a direct current bus side circuit is the minimum when the direct current bus side circuit reaches a stable state, the conduction loss and other energy losses of the switching tube are the minimum at the moment, and the energy transfer efficiency is the highest. And determining a bus voltage lower limit value according to the output voltage expected value of the low-voltage load, wherein the bus voltage lower limit value is the minimum voltage meeting the power supply requirement of the low-voltage load. Based on a preset rule, a bus voltage expected value which can meet the power supply requirement of a low-voltage load and can improve the energy transfer efficiency is determined according to a bus voltage initial value and a bus voltage lower limit value, and then the bus voltage is adjusted to follow the bus voltage expected value for dynamic adjustment. The technical scheme of the invention can improve the energy transfer efficiency under the condition of meeting the power supply requirement of the low-voltage load. Compared with the prior art, the circuit structure does not need to be changed or hardware equipment does not need to be added, and the cost is lower.
Drawings
FIG. 1 is a schematic diagram of a prior art magnetically integrated transducer;
FIG. 2 is a flow chart illustrating a method for controlling a converter according to an embodiment of the present invention;
FIG. 3 is a graph illustrating the DC/DC efficiency as a function of battery voltage at a bus voltage of 400V according to an embodiment of the present invention;
FIG. 4 is a graph illustrating the variation of DC/DC efficiency with the battery voltage when the bus voltage takes various voltage values according to an embodiment of the present invention;
FIG. 5 is a logic diagram illustrating phase shift control according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an inverter control device according to another embodiment of the present invention;
fig. 7 is a schematic structural diagram of a vehicle-mounted power supply according to another embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. While certain embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but rather are provided for a more thorough and complete understanding of the present invention. It should be understood that the drawings and the embodiments of the present invention are illustrative only and are not intended to limit the scope of the present invention.
It should be understood that the various steps recited in the method embodiments of the present invention may be performed in a different order and/or performed in parallel. Moreover, method embodiments may include additional steps and/or omit performing the illustrated steps. The scope of the invention is not limited in this respect.
The term "include" and variations thereof as used herein are open-ended, i.e., "including but not limited to". The term "based on" is "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "alternative embodiments". Relevant definitions for other terms will be given in the following description. It should be noted that the terms "first", "second", and the like in the present invention are only used for distinguishing different devices, modules or units, and are not used for limiting the order or interdependence relationship of the functions performed by the devices, modules or units.
It is noted that references to "a", "an", and "the" modifications in the present invention are intended to be illustrative rather than limiting, and that those skilled in the art will recognize that reference to "one or more" unless the context clearly dictates otherwise.
The names of messages or information exchanged between devices in the embodiments of the present invention are for illustrative purposes only, and are not intended to limit the scope of the messages or information.
As shown in fig. 1, the magnetic integrated converter includes a dc bus side circuit, a transformer Tr, a high voltage side circuit, and a low voltage side circuit, where the dc bus side circuit includes a dc bus side capacitor C1, a dc blocking capacitor Cb, an inductor Lm, and a primary side full bridge circuit composed of four switching tubes Q1, Q2, Q3, and Q4, two ends of the dc bus side capacitor C1 are respectively connected to two ends of the primary side full bridge circuit, the dc blocking capacitor Cb and the inductor Lm are connected in series to form an LC circuit, two ends of the LC circuit are respectively connected to two bridge arm midpoints a and B in the primary side full bridge circuit, and the inductor Lm is further connected in parallel to the primary side winding of the transformer Tr.
The high-voltage side circuit comprises a high-voltage battery HV, a capacitor C2, a resonant capacitor Cr, a resonant inductor Lr and a secondary side full-bridge circuit consisting of four switching tubes Q5, Q6, Q7 and Q8, wherein the high-voltage battery HV is connected with the capacitor C2 in parallel, two ends of the high-voltage battery HV are respectively connected with two ends of the secondary side full-bridge circuit, one end of the resonant capacitor Cr is connected with one bridge arm midpoint C in the secondary side full-bridge circuit, and the other end of the resonant capacitor Cr is sequentially connected with a first secondary side winding and the resonant inductor Lr of a transformer Tr in series and is connected to the other bridge arm midpoint D of the secondary side full-bridge circuit.
The low-voltage side circuit comprises a synchronous rectification circuit consisting of two switching tubes Q9 and Q10, a BUCK circuit and a low-voltage load LV, the BUCK circuit comprises a switching tube Q11, a switching tube Q12, an inductor L and a capacitor C3, the low-voltage load LV is connected with the capacitor C3 in parallel, one end of the low-voltage load LV is connected with one end of the inductor L, the other end of the inductor L is connected to the second end of the second secondary winding of the transformer Tr through the switching tube Q11, the other end of the inductor L is further connected to the other end of the low-voltage load LV through the switching tube Q12, the other end of the low-voltage load LV is connected to the first end of the second secondary winding through the switching tube Q9, and is further connected to the third end of the second secondary winding through the switching tube Q10.
Besides the DC/DC mode, the magnetic integrated converter also comprises the following three energy flow directions: (1) energy flows from the direct-current bus side circuit to the high-voltage side circuit, the direct-current bus side circuit is connected to a Power grid through a front-stage PFC (Power Factor Correction) circuit, the PFC circuit boosts and converts alternating current of the Power grid into direct-current bus capacitor voltage, and the high-voltage battery is charged through the primary side full-bridge circuit, the transformer and the secondary side full-bridge circuit; (2) energy flows from a direct current bus side circuit to a low-voltage side circuit, a PDC circuit converts the alternating current of a power grid, and the alternating current of the power grid is supplied to a low-voltage load through a primary side full-bridge circuit, a transformer, a synchronous rectification circuit and a BUCK circuit; (3) energy flows from the high-voltage side circuit to the direct-current bus side circuit, and the energy flow direction is opposite to the energy flow direction of the type (1), and the detailed description is omitted.
First, a description will be given of a principle in which energy flow loss in the DC/DC mode affects the power supply of the low-voltage load, and when energy flows from the high-voltage side circuit to the DC bus side circuit, the bus capacitor is charged, energy flows from the DC bus side circuit to the low-voltage side circuit, the bus capacitor voltage decreases due to the load of the magnetic integrated converter, and the current in the DC bus side circuit increases due to the decrease in the capacitor voltage based on the principle of power conservation.
According to a calculation formula of the conduction loss of the switching tube:
and the copper loss calculation formula of the transformer is as follows:
wherein, Pcond For conducting the power loss, R, of the switching tubeds Is the on-resistance of the switching tube, PT-Cu Is the copper loss power of the transformer, Rp Equivalent internal resistance of transformer, Irms The effective value of the direct current bus side current.
Therefore, the current on the side of the direct current bus increases, which may cause the loss of the switching tube and the loss of the transformer in the primary full-bridge circuit to increase, and the power transfer efficiency is reduced, thereby affecting the power supply power of the low-voltage load.
It should be noted that, if each switching tube in the primary side full bridge circuit is turned off in the DC/DC mode, the energy flowing to the DC bus side circuit can still charge the bus capacitor through the parasitic diode of the switching tube, and the energy flowing speed is fast, which is likely to cause the situation of overcharge, etc., so that the energy flowing in the DC/DC mode still needs to be controlled through the switching tube in the primary side full bridge circuit.
As shown in fig. 2, an embodiment of the present invention provides a converter control method applicable to a magnetic integrated converter, including:
in step S110, when the converter is in the DC/DC mode, the battery voltage across the high voltage battery is acquired.
Specifically, it may be determined in advance whether the converter operates in the DC/DC mode, and if so, the battery voltage is collected.
And step S120, determining the initial value of the bus voltage at the two ends of the bus capacitor in the uncontrolled rectification state according to the battery voltage, and determining the lower limit value of the bus voltage at the two ends of the bus capacitor according to the expected value of the output voltage of the low-voltage load.
Optionally, the uncontrolled rectification state indicates that energy flows only from the high-voltage side circuit to the dc bus side circuit, and a phase difference between the primary side full bridge circuit and the secondary side full bridge circuit is 0.
Specifically, the uncontrolled rectification state represents a stage in which energy flows only from the high-voltage side circuit to the dc bus side circuit, but not from the dc bus side circuit to the low-voltage side circuit, at this time, the switching tube in the low-voltage side circuit is turned off, and the phase difference between the primary side full bridge circuit and the secondary side full bridge circuit is 0, the duty ratios of the switching tube in the primary side full bridge circuit and the switching tube in the secondary side full bridge circuit in the steady state are both 0.5, no phase shift control is performed on the switching tube, and the energy loss in the converter is minimum at this time. It can also be understood that the stable state is achieved under the uncontrolled rectification state, the bus capacitor is not charged any more, and at the moment, the current in the direct current bus side circuit is minimum, and the energy loss is minimum. Therefore, the initial value of the bus voltage in the uncontrolled rectification state corresponds to the voltage across the bus capacitor when the energy loss is minimum.
Meanwhile, the bus voltage lower limit value determined according to the output voltage expected value of the low-voltage load is the lowest voltage which ensures the power supply requirement of the low-voltage side.
Step S130, based on a preset rule, determining a bus voltage expected value according to the bus voltage initial value and the bus voltage lower limit value.
Specifically, a bus voltage expected value which can ensure the power supply requirement of a low-voltage load and can improve the energy transfer efficiency is determined according to a preset rule.
And step S140, regulating the bus voltage at two ends of the bus capacitor according to the expected bus voltage value.
Specifically, the bus voltage is adjusted to follow the expected bus voltage value, so that the power supply requirement of a low-voltage load can be met, the energy loss is reduced, and the energy transfer efficiency is improved, wherein the energy transfer efficiency refers to the DC/DC efficiency when the energy of a high-voltage side circuit is transferred to a low-voltage side circuit.
In this embodiment, it may be determined in advance whether the converter is in the DC/DC mode, and if so, the battery voltage at both ends of the high-voltage battery may be obtained. The method comprises the steps that a bus voltage initial value at two ends of a bus capacitor in an uncontrolled rectification state is calculated according to the voltage of a battery, a switching tube in a converter is not subjected to phase shift control in the uncontrolled rectification state, the current in a direct current bus side circuit is the minimum when the direct current bus side circuit reaches a stable state, the conduction loss and other energy losses of the switching tube are the minimum at the moment, and the energy transfer efficiency is the highest. And determining a bus voltage lower limit value according to the output voltage expected value of the low-voltage load, wherein the bus voltage lower limit value is the minimum voltage meeting the power supply requirement of the low-voltage load. Based on a preset rule, a bus voltage expected value which can meet the power supply requirement of a low-voltage load and can improve the energy transfer efficiency is determined according to a bus voltage initial value and a bus voltage lower limit value, and then the bus voltage is adjusted to follow the bus voltage expected value for dynamic adjustment. The technical scheme of the invention can improve the energy transfer efficiency under the condition of meeting the power supply requirement of the low-voltage load. Compared with the prior art, the circuit structure does not need to be changed or hardware equipment does not need to be added, and the cost is lower.
Optionally, the determining, according to the battery voltage, a bus voltage initial value at two ends of the bus capacitor in the uncontrolled rectification state includes:
based on a bus voltage calculation model, determining an initial value of the bus voltage according to the battery voltage, and a predetermined number of turns of a primary winding, a predetermined number of turns of a first secondary winding and a predetermined first correction parameter;
wherein the first correction parameter is associated with a loss voltage in the high-side circuit and the direct-current bus-side circuit in the uncontrolled rectifying state.
Specifically, the bus voltage calculation model can be established in advance according to device parameters (such as inductance, capacitance, turn ratio and the like) in the circuit. Bus voltage U at two ends of bus capacitorBUS Number of turns N of receiving primary windingBUS The number of turns N of the first secondary windingHV And the number of turns N of the second secondary windingLV Voltage of battery UHV And output voltage desired value ULV The functional relationship can be expressed as: u shapeBUS ＝f(NHV ,NLV ,NBUS ,UHV ,ULV )。
In a theoretical state, the initial value U of the bus voltage in an uncontrolled rectification state can be determined according to the transformer ratio relation of the transformerBUS And battery voltage UHV The relationship can be expressed by a first formula, and the first formula comprises:
UBUS ＝UHV *NBUS /NHV (formula one)
However, in actual operation, the conditions of inductance, capacitance voltage division, conduction loss of a switch tube, loss of a transformer, line loss of a connecting wire and the like need to be considered, so that the initial value U of the bus voltage in actual conditions can be obtainedBUS And battery voltage UHV The relationship between the first and second elements is modified, and the modified relationship can be expressed by a second formula, which includes:
UBUS ＝α1 *UHV *NBUS /NHV +ΔU1 (formula two)
Wherein alpha is1 And Δ U1 A first correction parameter is expressed, which is related to inductance, capacitance, turns ratio, tube voltage drop and the like in the high-voltage side circuit and the direct-current bus side circuit in an uncontrolled rectification state, and the functional relation can be expressed as (delta U, alpha) ═ f (L)r ,Cr ,Cb ,NHV ,NBUS MOSFET), where Lr denotes a resonant inductance in the high-voltage side circuit, Cr denotes a resonant capacitance in the high-voltage side circuit, Cb denotes a dc blocking capacitance in the dc bus side circuit, NHV Representing the number of turns of the first secondary winding, NBUS The number of primary winding turns is shown, and the MOSFETs show switching tubes Q1, Q2, Q3, Q4 in the dc bus side circuit and switching tubes Q5, Q6, Q7, Q8 in the high side circuit.
In this optional embodiment, the bus voltage initial value is calculated according to the predetermined bus voltage calculation model and the battery voltage, when the combination of the battery voltage and the bus voltage initial value is maintained, the current in the direct current bus side circuit is minimum, the energy loss is minimum, and the energy transfer efficiency in the DC/DC mode can be the highest by adjusting the bus voltage to follow the bus voltage initial value.
Optionally, the first correction parameter is determined according to a voltage equivalent transformation method and/or an experimental data fitting method.
Specifically, the voltage equivalent transformation method refers to the determination of an initial value U of the bus voltage in an actual situation according to kirchhoff's law in an uncontrolled rectification stateBUS And the voltage U of the batteryHV The relationship can be expressed by a third formula, which includes:
UBUS ＝UHV *NBUS /NHV -UL -UC -UMOSFET -UT (formula three)
Wherein, UL Representing the voltage across the inductor Lr, U, in the circuit in the uncontrolled rectifying stateC Representing the sum of the voltages of the capacitors in the circuit in the uncontrolled rectifying state, i.e. the sum of the voltage of the capacitor Cr and the voltage of the capacitor Cb, UMOSFET Indicating the tube voltage drop, U, in the circuit in the uncontrolled rectifying stateT Representing the voltage drop caused by the transformer under the condition of uncontrolled rectification, and determining a group alpha by combining the second formula and the third formula1 And Δ U1 The value of (c).
The experimental data fitting method is that the bus voltage when the energy transfer efficiency is highest corresponding to different battery voltages is determined through experiments, and alpha can be obtained by fitting according to a plurality of experimental results by adopting a second formula1 And Δ U1 A set of values of (a).
As shown in fig. 3, when the bus voltage is 400V, the DC/DC efficiency (i.e., energy transfer efficiency) increases to 90.88% of the maximum efficiency with increasing cell voltage, and the corresponding cell voltage is 390V and then gradually decreases.
In fig. 4, the bus voltages corresponding to the curves from left to right are 400V, 395V, 390V, 385V, 380V, 375V, 370V, 365V, 360V and 355V in sequence, of two numbers on each curve, the former number represents the battery voltage at the time of the highest efficiency, and the latter number represents the highest efficiency value, for example, (385, 91.04) on the second curve corresponding to thebus voltage 395V represents that the maximum DC/DC efficiency value corresponding to thebus voltage 395V is 91.04%, and the battery voltage at this time is 385V. As can be seen from fig. 4, the DC/DC efficiency for each curve increases to the maximum efficiency and then decreases gradually as the cell voltage increases.
Therefore, when the battery voltage is fixed, the bus voltage at the maximum efficiency corresponding to the battery voltage is determined so that the voltage across the bus capacitor is maintained at the bus voltage, thereby maximizing the DC/DC efficiency. And determining a group of first correction parameters according to the bus voltage and the battery voltage of each group corresponding to the maximum efficiency in the experimental result by using a second formula.
Optionally, the determining a lower limit value of a bus voltage across the bus capacitor according to the expected output voltage value of the low-voltage load includes:
and determining the lower limit value of the bus voltage according to the expected output voltage value, the number of primary winding turns, the number of second secondary winding turns and a second correction parameter, wherein the second correction parameter is related to loss voltages in the direct current bus side circuit and the low voltage side circuit.
Specifically, in a theoretical state, the relationship between the expected output voltage value of the low-voltage load and the lower limit value of the bus voltage can be expressed as UBUSMIN ＝f(NLV ,NBUS ,ULV ) Wherein, UBUSMIN Denotes the bus voltage lower limit, NLV Representing the number of turns of the second secondary winding, NBUS Representing the number of turns of the primary winding, ULV Indicating the desired value of the output voltage. However, in actual operation, the inductance, the capacitance voltage division, the energy loss and the like are also considered, so the actual relationship can be expressed by a fourth formula, the second formulaThe four formulas include:
UBUSMIN ＝α2 *ULV *NBUS /NLV +ΔU2 (formula four)
Wherein alpha is2 And Δ U2 Indicating the second correction parameter.
In this optional embodiment, the bus voltage lower limit values at two ends of the bus capacitor are calculated according to the output voltage expected value, the voltage expected value is the output voltage meeting the power supply requirement of the low-voltage load, the bus voltage lower limit value is the minimum bus voltage meeting the power supply requirement of the low-voltage load, and the power supply power of the low-voltage load can be ensured by adjusting the bus voltage to follow the bus voltage lower limit values.
Optionally, the second correction parameter is determined according to a voltage equivalent transformation method and/or an experimental data fitting method.
Specifically, the process of determining the second correction parameter according to the voltage equivalent transformation method and/or the experimental data fitting method is similar to the process of determining the first correction parameter, and only the corresponding parameter is replaced, and the specific process is not described herein again.
Optionally, the determining, based on a preset rule, a bus voltage expected value according to the bus voltage initial value and the bus voltage lower limit value includes: and determining the maximum value of the bus voltage initial value and the bus voltage lower limit value as the bus voltage expected value.
Specifically, the process of determining the desired bus voltage may be represented by a fifth equation, which includes:
UBUSref ＝max(UBUS ,UBUSMIN ) (formula five)
Wherein, UBUSref Indicating desired value of bus voltage, UBUS Indicating the initial value of the bus voltage, UBUSMIN Represents the bus voltage lower limit.
The bus voltage initial value represents the bus voltage when the energy transfer efficiency is highest in the circuit, and the bus voltage lower limit value represents the minimum bus voltage for ensuring the power supply requirement of the low-voltage load, wherein the priority for meeting the power supply requirement of the low-voltage load is higher than the priority for improving the energy transfer efficiency.
When the initial value of the bus voltage is greater than or equal to the lower limit value of the bus voltage, the initial value of the bus voltage is taken as the expected value of the bus voltage to regulate the bus voltage, so that the energy loss can be reduced to the maximum extent, the energy transfer efficiency is improved, and the power supply power of a low-voltage load can be ensured; when the initial value of the bus voltage is smaller than the lower limit value of the bus voltage, the bus voltage is adjusted by taking the lower limit value of the bus voltage as the expected value of the bus voltage, although the energy transfer efficiency is not in the highest state, the power supply power of a low-voltage load can be ensured, and experiments show that the invention can improve the energy transfer efficiency to a certain extent compared with the condition that the bus voltage is fixed.
In this optional embodiment, the maximum value of the initial value of the bus voltage and the lower limit value of the bus voltage is determined to be the expected value of the bus voltage, so that the power supply requirement of the low-voltage load can be ensured when the bus voltage is subsequently adjusted, and the energy transfer efficiency can be improved.
Optionally, the adjusting the bus voltage across the bus capacitor according to the desired bus voltage value includes:
acquiring actual bus voltage values at two ends of the bus capacitor, and determining a difference value between the expected bus voltage value and the actual bus voltage value;
and carrying out voltage loop PI control according to the difference value, and adjusting the phase difference between the primary side full-bridge circuit and the secondary side full-bridge circuit so as to adjust the bus voltage.
Specifically, as shown in fig. 5, a difference between the expected value of the bus voltage and the actual value of the bus voltage may be used as an input of the voltage loop PI controller, a phase-shifted duty ratio of the switching tubes in the primary full-bridge circuit and the secondary full-bridge circuit is output, and a phase difference is adjusted according to the phase-shifted duty ratio to adjust the bus voltage to follow the expected value of the bus voltage.
Optionally, after the bus voltage across the bus capacitor is adjusted according to the desired bus voltage value, the method further includes: and when the bus voltage reaches the bus voltage expected value, controlling the switch tube in the low-voltage side circuit to be conducted.
In this optional embodiment, when the bus voltage reaches the expected value of the bus voltage, the switching tube in the low-voltage side circuit is controlled to be turned on to supply power to the low-voltage load, and at this time, the bus voltage can be dynamically adjusted according to the expected value of the bus voltage and quickly restored to a balanced state, so that the time for dynamic adjustment can be shortened, and the DC/DC mode is ensured to work under a high-efficiency working condition.
As shown in fig. 6, another embodiment of the present invention provides an inverter control device including:
the acquisition module is used for acquiring the battery voltage at two ends of the high-voltage battery when the converter is in a DC/DC mode;
the processing module is used for determining bus voltage initial values at two ends of the bus capacitor in an uncontrolled rectification state according to the battery voltage and determining bus voltage lower limit values at two ends of the bus capacitor according to an output voltage expected value of a low-voltage load; determining a bus voltage expected value according to the bus voltage initial value and the bus voltage lower limit value based on a preset rule;
and the control module is used for adjusting the bus voltage at two ends of the bus capacitor according to the expected bus voltage value.
The inverter control device of the present embodiment is used for implementing the inverter control method as described above, and the beneficial effects of the two correspond, which are not described herein again.
Optionally, the processing module is specifically configured to: determining the initial value of the bus voltage according to the battery voltage, the number of turns of a primary winding, the number of turns of a first secondary winding and a first correction parameter which are predetermined; the first correction parameter is associated with loss voltages in the high-voltage side circuit and the direct-current bus side circuit in the uncontrolled rectification state, the uncontrolled rectification state represents that energy flows from the high-voltage side circuit to the direct-current bus side circuit only, and the phase difference between the primary side full bridge circuit and the secondary side full bridge circuit is 0.
Optionally, the processing module is further specifically configured to: and determining the lower limit value of the bus voltage according to the expected value of the output voltage, and a predetermined number of turns of a primary winding, a predetermined number of turns of a second secondary winding and a predetermined second correction parameter, wherein the second correction parameter is associated with loss voltages in the direct-current bus side circuit and the low-voltage side circuit, and the first correction parameter and the second correction parameter are determined according to a voltage equivalent transformation method and/or an experimental data fitting method.
Optionally, the processing module is further specifically configured to: and determining the maximum value of the initial bus voltage value and the lower bus voltage limit value as the expected bus voltage value.
Optionally, the control module is specifically configured to: acquiring actual bus voltage values at two ends of the bus capacitor, and determining a difference value between the expected bus voltage value and the actual bus voltage value; and carrying out voltage loop PI regulation according to the difference value, outputting a first phase shift angle of the primary side full-bridge circuit and a second phase shift angle of the secondary side full-bridge circuit, and regulating the phase difference between the primary side full-bridge circuit and the secondary side full-bridge circuit according to the first phase shift angle and the second phase shift angle.
Another embodiment of the present invention provides an electronic device, including a memory and a processor; the memory for storing a computer program; the processor, when executing the computer program, is configured to implement the converter control method as described above.
As shown in fig. 7, a vehicle-mounted power supply according to still another embodiment of the present invention includes an inverter and the electronic device as described above, where the electronic device is electrically connected to each switching tube in the inverter, and the electronic device is configured to control each switching tube to turn on and off.
An electronic device that can be a server or a client of the present invention, which is an example of a hardware device that can be applied to aspects of the present invention, will now be described. Electronic devices are intended to represent various forms of digital electronic computer devices, such as industrial computers, laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions, are meant to be exemplary only, and are not meant to limit implementations of the inventions described and/or claimed herein.
The electronic device includes a computing unit that can perform various appropriate actions and processes according to a computer program stored in a Read Only Memory (ROM) or a computer program loaded from a storage unit into a Random Access Memory (RAM). In the RAM, various programs and data required for the operation of the device can also be stored. The computing unit, the ROM, and the RAM are connected to each other by a bus. An input/output (I/O) interface is also connected to the bus.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like. In this application, the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment of the present invention. In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present disclosure, and these changes and modifications are intended to be within the scope of the present disclosure.
Claims (10)
1. A converter control method, comprising:
when the converter is in a DC/DC mode, acquiring battery voltages at two ends of the high-voltage battery;
determining initial values of bus voltages at two ends of a bus capacitor under an uncontrolled rectification state according to the battery voltage, and determining lower values of the bus voltages at two ends of the bus capacitor according to expected values of output voltages of low-voltage loads;
determining a bus voltage expected value according to the bus voltage initial value and the bus voltage lower limit value based on a preset rule;
and regulating the bus voltage at two ends of the bus capacitor according to the expected bus voltage value.
2. The converter control method of claim 1, wherein said determining an initial value of a bus voltage across an uncontrolled rectifying state bus capacitor based on said battery voltage comprises:
based on a bus voltage calculation model, determining an initial value of the bus voltage according to the battery voltage, and a predetermined number of turns of a primary winding, a predetermined number of turns of a first secondary winding and a predetermined first correction parameter;
wherein the first correction parameter is associated with loss voltages in the high-voltage side circuit and the direct-current bus side circuit in the uncontrolled rectifying state.
3. The converter control method according to claim 2, wherein the uncontrolled rectifying state indicates that energy flows only from the high-voltage side circuit to the dc bus side circuit, and a phase difference between the primary side full bridge circuit and the secondary side full bridge circuit is 0.
4. The converter control method according to claim 2 or 3, wherein the determining a lower bus voltage limit across the bus capacitor according to the desired output voltage of the low-voltage load comprises:
and determining the lower limit value of the bus voltage according to the expected output voltage value, the number of primary winding turns, the number of second secondary winding turns and a second correction parameter, wherein the second correction parameter is related to loss voltages in the direct current bus side circuit and the low voltage side circuit.
5. The converter control method according to claim 4, characterized in that the first correction parameter and the second correction parameter are determined according to a voltage equivalent transformation method and/or an experimental data fitting method.
6. The converter control method according to any one of claims 1 to 3, wherein the determining a desired bus voltage value from the initial bus voltage value and the bus voltage lower limit value based on a preset rule comprises: and determining the maximum value of the initial bus voltage value and the lower bus voltage limit value as the expected bus voltage value.
7. The converter control method according to any one of claims 1 to 3, wherein said adjusting the bus voltage across the bus capacitor according to the desired bus voltage value comprises:
acquiring actual bus voltage values at two ends of the bus capacitor, and determining a difference value between the expected bus voltage value and the actual bus voltage value;
and carrying out voltage loop PI control according to the difference value, and adjusting the phase difference between the primary side full-bridge circuit and the secondary side full-bridge circuit so as to adjust the bus voltage.
8. The converter control method according to any one of claims 1 to 3, further comprising, after the adjusting the bus voltage across the bus capacitor according to the desired bus voltage value: and when the bus voltage reaches the bus voltage expected value, controlling the switch tube in the low-voltage side circuit to be conducted.
9. An inverter control device, comprising:
the acquisition module is used for acquiring the battery voltage at two ends of the high-voltage battery when the converter is in a DC/DC mode;
the processing module is used for determining bus voltage initial values at two ends of the bus capacitor in an uncontrolled rectification state according to the battery voltage and determining bus voltage lower limit values at two ends of the bus capacitor according to an output voltage expected value of a low-voltage load; based on a preset rule, determining a bus voltage expected value according to the bus voltage initial value and the bus voltage lower limit value;
and the control module is used for adjusting the bus voltage at two ends of the bus capacitor according to the expected bus voltage value.
10. The vehicle-mounted power supply is characterized by comprising a converter and electronic equipment, wherein the electronic equipment is electrically connected with each switching tube in the converter respectively;
the electronic device comprises a memory and a processor; the memory for storing a computer program; the processor, when executing the computer program, is configured to implement the converter control method according to any one of claims 1 to 8.
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| CN202210261973.5ACN114825952A (en) | 2022-03-17 | 2022-03-17 | Converter control method and device and vehicle-mounted power supply |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116160885A (en)* | 2023-04-12 | 2023-05-26 | 合肥阳光电动力科技有限公司 | A vehicle charger and its control method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116160885A (en)* | 2023-04-12 | 2023-05-26 | 合肥阳光电动力科技有限公司 | A vehicle charger and its control method |
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