Disclosure of Invention
The invention aims to provide a battery bidirectional equalization control method and a control circuit, which can solve the problem that two power MOS (metal oxide semiconductor) tubes on the primary side and the secondary side are simultaneously conducted in the prior art.
The invention aims at realizing the following technical scheme:
in one aspect, the invention provides a battery bidirectional equalization control method, which comprises the following steps:
s1, a first bidirectional switching circuit and a signal isolation device receive an external control signal;
S2, if the control signal is a forward working signal, the first bidirectional switching circuit detects the working voltage of the first winding of the transformer, and when the working voltage of the first winding is stable, the first bidirectional switching circuit controls the first switch and the rectifying device to be conducted through the first main controller, the signal isolation device inverts and outputs the control signal to the second bidirectional switching circuit to turn to S3, or
If the control signal is a forward working signal, the first bidirectional switching circuit delays for a period of time and then controls the first switch and the rectifying device to be conducted through the first main controller;
if the control signal is a reverse working signal, the first bidirectional switching circuit controls the first switch and the rectifying device to be turned off through the first main controller, and the signal isolation device inverts and outputs the control signal to the second bidirectional switching circuit to switch to S4;
S3, the second bidirectional switching circuit controls the second switch and the rectifying device to be turned off through the second main controller, and the S1 is returned;
S4, the second bidirectional switching circuit detects the working voltage of the second winding of the transformer, and when the working voltage of the second winding is stable, the second bidirectional switching circuit controls the second switch and the rectifying device to be conducted through the second main controller to return to S1, or
And after the second bidirectional switching circuit delays for a period of time, the second switch and the rectifying device are controlled to be conducted through the second main controller, and the S1 is returned.
On the other hand, the invention provides a battery bidirectional equalization control circuit, which comprises a transformer, a signal isolation device, a first switch and a rectifying device which are sequentially connected between a first winding of the transformer and one end of the signal isolation device, a first master controller and a first bidirectional switching circuit, and a second switch and rectifying device, a second master controller and a second bidirectional switching circuit which are sequentially connected between a second winding of the transformer and the other end of the signal isolation device;
The input end of the first bidirectional switching circuit inputs a control signal, controls the first switch and the rectifying device to be turned off according to the control signal, detects the voltage signal of the first winding of the transformer, controls the first switch and the rectifying device to be turned on according to the control signal and the voltage signal of the first winding, or
The input end of the first bidirectional switching circuit inputs a control signal, the first switch and the rectifying device are controlled to be turned off according to the control signal, and the first switch and the rectifying device are controlled to be turned on after a period of time is delayed according to the control signal;
one end of the signal isolation device receives the control signal and outputs the control signal to the second bidirectional switching circuit from the other end of the signal isolation device after transmission;
The input end of the second bidirectional switching circuit inputs the control signal transmitted by the signal isolation device, controls the second switch and the rectifying device to be turned off according to the control signal transmitted by the signal isolation device, detects the voltage signal of the second winding of the transformer, controls the second switch and the rectifying device to be turned on according to the control signal transmitted by the signal isolation device and the voltage signal of the second winding, or
The input end of the second bidirectional switching circuit inputs a control signal transmitted by the signal isolation device, controls the second switch and the rectifying device to be turned off according to the control signal transmitted by the signal isolation device, and controls the second switch and the rectifying device to be turned on after a period of time is delayed according to the control signal.
Further, the first master or the second master includes a PWM controller.
Further, the first switch and rectifier device comprises a first MOS tube TR1 and a first diode D1, the second switch and rectifier device comprises a second MOS tube TR2 and a second diode D2, the positive electrode of the first diode D1 is respectively connected with the source electrode of the first MOS tube TR1, the positive electrode of the second diode D2 and the source electrode of the second MOS tube TR2, the negative electrode of the first diode D1 is respectively connected with the drain electrode of the first MOS tube TR1 and one end of the first winding, the negative electrode of the second diode D2 is respectively connected with the drain electrode of the second MOS tube TR2 and one end of the second winding, the grid electrode of the first MOS tube TR1 is connected with the PWM controller in the first main controller, and the grid electrode of the second MOS tube TR2 is connected with the PWM controller in the second main controller.
Further, the first master controller or the second master controller comprises a PWM controller and a synchronous rectification controller which are connected in parallel.
Further, the first switch and rectifying device is a first MOS tube TR1, the second switch and rectifying device is a second MOS tube TR2, a source electrode of the first MOS tube TR1 is connected with the ground GND_P on one side of a first winding of the transformer, a source electrode of the second MOS tube TR2 is connected with the ground GND_S on one side of a second winding of the transformer, a drain electrode of the first MOS tube TR1 is connected with one end of the first winding, a drain electrode of the second MOS tube TR2 is connected with one end of the second winding, a grid electrode of the first MOS tube TR1 is connected with a first main controller, and a grid electrode of the second MOS tube TR2 is connected with a second main controller.
Further, the first bidirectional switching circuit or the second bidirectional switching circuit comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first comparator COMP1, a second comparator COMP2, a third comparator COMP3, a first capacitor C1, a first RS trigger RS1, a first NOT1 AND a first AND gate AND1, wherein the reverse input end of the second comparator COMP2 is used as the input end of the first bidirectional switching circuit or the input end of the second bidirectional switching circuit, one end of the first resistor R1 is connected with one end of a first winding or one end of the second winding, the other end of the first resistor R1 is respectively connected with one end of the second resistor R2 AND the reverse input end of the third comparator COMP3, the forward input end of the second comparator COMP2 AND the forward input end of the first comparator COMP1 are respectively input with reference voltages, the output end of the third comparator COMP3 is connected with the output end of the first comparator R3, the other end of the first comparator COMP1 is connected with the other end of the first comparator COMP1, the other end of the second comparator COMP2 is connected with the first end of the first resistor R1 is connected with the other end of the first resistor R1, the output end of the second comparator COMP2 is respectively connected with one input end of the first AND gate AND1 AND the input end of the first NOT gate NOT1, the output end of the first NOT gate NOT1 is connected with the R end of the first RS trigger RS1, the Q end of the first RS trigger RS1 is connected with the other input end of the first AND gate AND1, AND the output end of the first AND gate AND1 outputs a PWM control signal pwm_en to a PWM controller of the first master controller or a PWM controller of the second master controller.
Further, the first bidirectional switching circuit or the second bidirectional switching circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first comparator COMP1, a second comparator COMP2, a third comparator COMP3, a first capacitor C1, a first RS flip-flop RS1, a first NOT gate NOT1, AND a first AND gate AND1; the reverse input end of the second comparator COMP2 is used as the input end of the first bidirectional switching circuit or the input end of the second bidirectional switching circuit, one end of the first resistor R1 is connected with one end of the first winding or one end of the second winding, the other end of the first resistor R1 is respectively connected with one end of the second resistor R2 AND the reverse input end of the third comparator COMP3, the forward input end of the second comparator COMP2 AND the forward input end of the first comparator COMP1 are respectively input with a reference voltage REF, the output end of the third comparator COMP3 is connected with one end of the third resistor R3, the other end of the third resistor R1 is respectively connected with one end of the first capacitor C1, one end of the fourth resistor R4 AND the reverse input end of the first comparator COMP1, the other end of the second resistor R2, the other end of the first capacitor C1 AND the other end of the fourth resistor R4 are respectively connected with the ground GND_P on one side of the first winding or the ground GND_S on one side of the second winding, the output end of the first comparator COMP1 is respectively connected with the output end of the first comparator RS1 AND the output end of the first comparator RS1 is connected with the first NOT1 AND the output end of the first comparator RS1 respectively, AND outputs a synchronous rectification control signal SR_EN to the synchronous rectification controller of the first master controller or the synchronous rectification controller of the second master controller, wherein the Q end of the first RS trigger RS1 is connected with the other input end of the first AND gate AND1, AND the output end of the first AND gate AND1 outputs a PWM control signal PWM_EN to the PWM controller of the first master controller or the PWM controller of the second master controller.
Further, the first bidirectional switching circuit or the second bidirectional switching circuit comprises a first resistor R1, a second resistor R2, a counter, a second comparator COMP2, a first RS trigger RS1 AND a first AND gate AND1, wherein the reverse input end of the second comparator COMP2 is used as the input end of the first bidirectional switching circuit or the input end of the second bidirectional switching circuit, the forward input end of the second comparator COMP2 is input with a reference voltage REF, one end of the first resistor R1 is connected with one end of the first winding or one end of the second winding, the other end of the first resistor R1 is respectively connected with one end of the second resistor R2 AND a reset input port RS of the counter, the other end of the second resistor R2 is connected with a ground gnd_p on one side of the first winding or a ground gnd_s on one side of the second winding, the clock input port CT of the counter is input with a square wave signal CLK of a set number, the output end OUT of the counter is connected with the S end of the first RS trigger RS1, the output end of the second comparator COMP2 is respectively connected with one input end of the first AND gate AND1 or one end of the second AND gate, one end of the other end of the first AND gate is connected with the first PWM trigger RS1, AND the other end of the first PWM trigger RS1 is connected with the first PWM trigger RS 1.
Further, the first bidirectional switching circuit or the second bidirectional switching circuit comprises a first resistor R1, a second resistor R2, a counter, a second comparator COMP2, a first RS trigger RS1, a first NOT1 AND a first AND gate AND1, wherein the reverse input end of the second comparator COMP2 is used as the input end of the first bidirectional switching circuit or the input end of the second bidirectional switching circuit, the forward input end of the second comparator COMP2 is used for inputting a reference voltage REF, one end of the first resistor R1 is connected with one end of a first winding or one end of the second winding, the other end of the first resistor R1 is respectively connected with one end of the second resistor R2 AND the reset input port RS of the counter, the other end of the second resistor R2 is connected with the ground gnd_p on one side of the first winding or the ground gnd_s on one side of the second winding, the clock input port CT of the counter is connected with the square wave signal CLK of a set number, the output end OUT of the counter is connected with the S end of the first comparator RS1, the output end of the second comparator COMP2 is respectively connected with the first AND gate AND1, the output end of the second comparator RS1 is connected with the first AND the output end of the first AND gate AND the first PWM controller, AND the other end of the first comparator is connected with the first PWM controller RS1 or the first PWM controller, AND the other end of the first comparator is connected with the first PWM controller AND the first comparator RS 1.
Further, the first bidirectional switching circuit or the second bidirectional switching circuit includes a fourth comparator COMP7, a fifth comparator COMP8, a fifth resistor R5, a first triode Q1 and a second capacitor C2, wherein a reverse input end of the fourth comparator COMP7 is used as an input end of the first bidirectional switching circuit or an input end of the second bidirectional switching circuit, a forward input end of the fourth comparator COMP7 and a reverse input end of the fifth comparator COMP8 are used for inputting a reference voltage REF, an output end of the fourth comparator COMP7 is connected with one end of the fifth resistor R5 and a base electrode of the first triode Q1 respectively, the other end of the fifth resistor R5 is connected with an emitter electrode of the first triode Q1, one end of the second capacitor C2 and a forward input end of the fifth comparator COMP8 respectively, a collector electrode of the first triode Q1 and the other end of the second capacitor C2 are connected with a ground gnd_p on one side of the first winding or a ground gnd_s on one side of the second winding, and an output end of the fifth comparator COMP8 is connected with an output control signal of the pwm_master controller or the PWM controller.
Further, the first bidirectional switching circuit or the second bidirectional switching circuit comprises a fourth comparator COMP7, a fifth comparator COMP8, a fifth resistor R5, a first triode Q1, a second capacitor C2 and a second NOT2, wherein the reverse input end of the fourth comparator COMP7 is used as the input end of the first bidirectional switching circuit or the input end of the second bidirectional switching circuit, the forward input end of the fourth comparator COMP7 and the reverse input end of the fifth comparator COMP8 are used for inputting a reference voltage REF, the output end of the fourth comparator COMP7 is respectively connected with one end of the fifth resistor R5, the base of the first triode Q1 and the input end of the second NOT2, the output end of the second NOT2 outputs a synchronous rectification control signal sr_en to the synchronous rectification controller of the first master or the synchronous rectification controller of the second master, the collector of the first triode Q1 and the other end of the second capacitor C2 are connected with the ground gnd_p on one side of the first winding or the reverse input end of the fifth comparator COMP8, and the output end of the fourth comparator COMP7 is respectively connected with the input end of the base of the fifth resistor R5 and the input end of the second NOT2, and the output end of the synchronous rectification control signal sr_en to the synchronous rectification controller of the second master or the synchronous rectification controller of the second master is output of the synchronous rectification signal EN 2 to the synchronous rectification controller of the second master.
The invention relates to a battery bidirectional equalization control method and a control circuit, which are characterized in that when a control signal is at a high level, a switch and a rectifying device are turned off, and when the control signal is at a low level, whether the switch and the rectifying device are turned on or not is determined by detecting whether the voltage of a transformer winding is jumped or not. Or the switch and the rectifying device are turned on after a period of time. The invention can realize bidirectional transmission by only one signal isolation device, and solves the problem that the primary side switch and the rectifying device are simultaneously conducted in the prior art.
Detailed Description
Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.
Other advantages and effects of the present disclosure will become readily apparent to those skilled in the art from the following disclosure, which describes embodiments of the present disclosure by way of specific examples. It will be apparent that the described embodiments are merely some, but not all embodiments of the present disclosure. The disclosure may be embodied or practiced in other different specific embodiments, and details within the subject specification may be modified or changed from various points of view and applications without departing from the spirit of the disclosure. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by one of ordinary skill in the art without inventive effort, based on the embodiments in this disclosure are intended to be within the scope of this disclosure.
Example 1
In one aspect, the method for controlling bidirectional equalization of a battery according to the present embodiment includes the following steps:
s1, a first bidirectional switching circuit and a signal isolation device receive an external control signal;
S2, if the control signal is a forward working signal, the first bidirectional switching circuit detects the working voltage of the first winding of the transformer, and when the working voltage of the first winding is stable, the first bidirectional switching circuit controls the first switch and the rectifying device to be conducted through the first main controller;
if the control signal is a reverse working signal, the first bidirectional switching circuit controls the first switch and the rectifying device to be turned off through the first main controller, and the signal isolation device inverts and outputs the control signal to the second bidirectional switching circuit to switch to S4;
S3, the second bidirectional switching circuit controls the second switch and the rectifying device to be turned off through the second main controller, and the S1 is returned;
And S4, detecting the working voltage of a second winding of the transformer by a second bidirectional switching circuit, and controlling the second switch and the rectifying device to be conducted by the second bidirectional switching circuit through a second main controller when the working voltage of the second winding is stable, and returning to S1.
The first bidirectional switching circuit and the second bidirectional switching circuit are coupled to the winding voltage of the transformer, and when the voltage of the winding of the transformer is detected to be in a high-low jump state (namely, square wave signal), the opposite switch and rectifying device are still in switch operation, and the local PWM controller can be controlled to work only when the voltage of the winding of the transformer is required to be in a stable value (namely, in a high level). In the present invention, the first winding or the second winding may be a main power winding (primary winding or secondary winding) or an auxiliary winding.
The control signal CTL controls the battery bidirectional equalization control circuit to operate in the forward direction or in the reverse direction. The control signal CTL may be a forward operation of the battery bidirectional equalization control circuit at a high level or a forward operation of the battery bidirectional equalization control circuit at a low level, and for convenience of description, the forward operation state of the battery bidirectional equalization control circuit is described by taking the CTL at a low level as an example, but the scope of protection of the present invention is not limited thereto.
The signal isolation device generally generates transmission delay due to the characteristics of the device itself, and delays for a period of time after receiving the control signal CTL, so as to output the inverted control signal, which is determined by the characteristics of the device itself. Of course, the requirements of the invention can be met without a delayed signal isolation device.
When the forward operation and the reverse operation are switched, the switch and rectifying device 1 and the switch and rectifying device 2 cannot be in a switch mode at the same time, otherwise, the left switch and the right switch can be actively turned on, and then the transformer T1 is in a short circuit state, so that the device is damaged. When the switch and rectifying device 1 and the switch and rectifying device 2 are simultaneously in the rectifying mode, the primary side and the secondary side are not actively conducted, and problems are avoided, and the state is similar to a dead zone interval. In actual work, due to delay of signal transmission and signal switching, delay exists in mode switching of a switch and a rectifying device, and the circuit topology is at risk of being in a switch mode at the same time. In order to ensure reliable switching between the forward and the reverse, a certain dead zone interval must be reserved in the switching process, as shown in fig. 3.
On the other hand, as shown in fig. 2 and 4, the battery bidirectional equalization control circuit of the present embodiment includes a transformer T1 and a signal isolation device, and further includes a first switch and rectifying device 1, a first master controller 1 and a first bidirectional switching circuit 1 connected between a first winding of the transformer T1 and one end of the signal isolation device, and a second switch and rectifying device 2, a second master controller 2 and a second bidirectional switching circuit 2 connected between a second winding of the transformer T1 and the other end of the signal isolation device.
The input end of the first bidirectional switching circuit 1 is input with a control signal CTL, the first switch and the rectifying device 1 are controlled to be turned off according to the control signal CTL, the voltage signal of the first winding of the transformer T1 is detected, and the first switch and the rectifying device 1 are controlled to be turned on according to the control signal CTL and the voltage signal of the first winding.
One end of the signal isolation device receives the control signal CTL and outputs the control signal CTL to the second bidirectional switching circuit 2 from the other end of the signal isolation device after transmission. The signal isolation device transmits the control signal CTL, which is essentially the inversion of the level of the control signal CTL.
The input end of the second bidirectional switching circuit 2 inputs a control signal transmitted by the signal isolation device, controls the second switch and the rectifying device 2 to be turned off according to the control signal transmitted by the signal isolation device, detects a voltage signal of a second winding of the transformer T1, and controls the second switch and the rectifying device 2 to be turned on according to the control signal after overturning and the voltage signal of the second winding.
In a general application, two ends of the winding on two sides of the transformer T1 are connected to batteries, such as the battery 1 and the battery 2 in fig. 2. During the forward operation, the battery bidirectional equalization control circuit discharges the battery 1 to charge the battery 2, and during the reverse operation, the battery bidirectional equalization control circuit charges the battery 1 to discharge the battery 2.
The control process is that when the control signal CTL is low, the bidirectional switching circuit 1 controls the switch and the rectifying device 1 to work in a switch mode through the main controller 1, the control signal CTL is transmitted to the other end of the transformer through the signal isolator, the bidirectional switching circuit 2 controls the switch and the rectifying device 2 to work in a rectifying mode through the main controller 2, at the moment, the main power circuit forms a forward-working flyback circuit, the battery 1 is discharged as a power supply, and the battery 2 is charged as a load. When the CTL is at a high level, the main controller 1 controls the switch and the rectifying device 1 to work in a rectifying mode, the control signal CTL is transmitted to the right side through the signal isolator, the main controller 2 controls the switch rectifying device 2 to work in the switching mode, at the moment, the main power circuit forms a flyback circuit working reversely, the battery 1 is charged as a load, and the battery 2 is discharged as a power supply.
Further, the first master 1 or the second master 2 includes a PWM controller and a synchronous rectification controller connected in parallel, as shown in fig. 4. The operation in the switching mode is that the PWM controller is operated and the synchronous rectification controller is not operated, and the operation in the rectification mode is that the PWM controller is not operated and the synchronous rectification controller is operated.
The PWM controller may adopt any control method in the prior art, such as the voltage control method shown in fig. 14, and the pmw_en signal is used to cut off the connection or disconnection of the GT port of the PWM controller, so as to control whether the module works. The synchronous rectification controller can adopt any control mode in the prior art, such as the typical intermittent mode synchronous rectification control of fig. 7, and the connection with the GT port is cut off through the rs_en signal, so as to control whether the module works.
Further, the first switching and rectifying device 1 is a first MOS transistor TR1, and the second switching and rectifying device 2 is a second MOS transistor TR2. The source of the first MOS transistor TR1 is connected with the ground GND_P on the first winding side of the transformer, and the source of the second MOS transistor TR2 is connected with the ground GND_S on the second winding side of the transformer. The drain electrode of the first MOS tube TR1 is connected with one end of the first winding, and the drain electrode of the second MOS tube TR2 is connected with one end of the second winding. The grid electrode of the first MOS tube TR1 is connected with the first main controller 1, and the grid electrode of the second MOS tube TR2 is connected with the second main controller 2.
Further, as shown in fig. 5, the first bidirectional switching circuit 1 or the second bidirectional switching circuit 2 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first comparator COMP1, a second comparator COMP2, a third comparator COMP3, a first capacitor C1, a first RS flip-flop RS1, a first NOT gate NOT1, AND a first AND gate AND1. The inverting input terminal of the second comparator COMP2 serves as the input terminal of the first bidirectional switching circuit 1 or the input terminal of the second bidirectional switching circuit 2. One end of the first resistor R1 is connected to one end of the first winding or one end of the second winding. The other end of the first resistor R1 is connected to one end of the second resistor R2 and the inverting input terminal of the third comparator COMP3, respectively. The reference voltage REF is input to the positive input terminal of the third comparator COMP3, the positive input terminal of the second comparator COMP2, and the positive input terminal of the first comparator COMP1, respectively. The output end of the third comparator COMP3 is connected to one end of the third resistor R3, and the other end of the third resistor is connected to one end of the first capacitor C1, one end of the fourth resistor R4, and an inverting input end of the first comparator COMP1, respectively. The other end of the second resistor R2, the other end of the first capacitor C1, and the other end of the fourth resistor R4 are connected to the ground gnd_p on the first winding side or the ground gnd_s on the second winding side. The output end of the first comparator COMP1 is connected to the S end of the first RS flip-flop RS1, AND the output end of the second comparator COMP2 is connected to one input end of the first AND gate AND1 AND the input end of the first NOT gate NOT1, respectively. The output end of the first NOT1 is connected with the R end of the first RS trigger RS1, and outputs a synchronous rectification control signal SR_EN to a synchronous rectification controller in the first master controller or the second master controller. The Q terminal of the first RS flip-flop RS1 is connected to the other input terminal of the first AND gate AND1. The output terminal of the first AND gate AND1 outputs a PWM control signal pwm_en to the PWM controller in the first master or the second master.
The working principle of the invention is described below with reference to fig. 4 to 6:
According to the description of the background technology, when the primary side PWM controller and the secondary side PWM controller work simultaneously, the problem of reliability of simultaneous conduction of the MOS tubes of the primary side and the secondary side is caused. In order to solve the problem that the MOS tubes on the primary side and the secondary side are simultaneously conducted, when the bidirectional switching circuit wants to control the local PWM controller to work, whether the opposite PWM controller stops working or not needs to be detected. In this scheme, the bidirectional switching circuit is coupled to the winding voltage of the transformer (may be a main power winding or an auxiliary winding), and when detecting whether the voltage of the transformer is in a high-low jump state, this indicates that the opposite MOS transistor is still operating in a switch, and the local PWM controller can be controlled to operate only when the voltage of the transformer winding must wait for a stable value. Because the primary and secondary circuits are completely symmetrical, in the key node waveform diagram of fig. 6, the primary device or signal is denoted by the prefix p_and the secondary device or signal is denoted by the prefix s_.
When the control signal p_ctl=0 of the primary side is in forward operation, the control signal controls the PWM control signal p_pwm_en=1 output by the bidirectional switching circuit of the primary side to control the PWM controller of the primary side to operate, and controls the synchronous rectification control signal p_sr_en=0 output by the bidirectional switching circuit of the primary side to control the synchronous rectification controller of the primary side to not operate. Meanwhile, the signal S_CTL=1 output by the signal isolation device controls the PWM signal S_PWM_EN=0 output by the bidirectional switching circuit of the secondary side, controls the PWM controller of the secondary side to be not operated, and controls the synchronous rectification control signal S_SR_EN=1 output by the bidirectional switching circuit of the secondary side to control the synchronous rectification controller of the secondary side to be operated.
Coupled to fig. 6:
Before time t1, p_ctl=0, p_pwm_en=1, the primary side PWM controller is active, p_sr_en=0, the primary side synchronous rectification controller is inactive, s_ctl=1, p_pwm_en=0, the primary side PWM controller is inactive, s_sr_en=1, and the secondary side synchronous rectification controller is active.
At time t1, p_ctl changes from 0 to 1, at which time p_pwm_en=0, the primary PWM controller does not operate, p_sr_en=1, and the primary synchronous rectification controller operates. The secondary synchronous rectification controller works because of the transmission delay of the signal isolation device and the S_CTL is still kept to be 1. As the description of the background art shows, when the synchronous rectification controllers of the primary side and the secondary side work simultaneously, dead time is not caused to cause reliability problems.
At time t2, s_ctl goes to 0, when it is detected that the voltage VDS of the secondary winding of the transformer is maintained at a high voltage (i.e. the voltage across the battery 2), proving that the PWM controller on the primary side is already inactive. The comparator S_COMP3 outputs a low level to enable the voltage of the capacitor S_C1 to be reduced, when the voltage of the capacitor S_C1 is lower than the reference voltage REF, the S input end of the S_RS1 trigger receives a rising edge signal, the Q end of the S_RS1 outputs a high level, meanwhile, the output end of the comparator S_COMP2 is also high level, finally, the AND gate S_AND1 outputs a high level, AND the PWM controller of the secondary side is controlled to work. In the process of switching forward operation to reverse operation, the condition that the PWM controllers on the two sides of the primary side and the secondary side work simultaneously cannot occur.
At time t3, p_ctl changes from 1 to 0, at which point p_sr_en=1, the synchronous rectification controller on the primary side operates, and the comparator p_comp2 outputs a high level. However, at this time, because the transmission delay of the signal isolation device is not enough, the PWM controller on the secondary side is still operating, the voltage of p_vds is a square wave signal, the output of p_comp3 is also a square wave signal, so that the average voltage of p_c1 is higher than the reference voltage REF, the output of the comparator p_comp1 maintains a low level, p_rss 1 also outputs a low level, AND the AND gate p_and1 also outputs a signal p_pwm_en low level, so that the PWM controller on the primary side will not operate. The simultaneous operation of the PWM controllers on the primary side and the secondary side is avoided.
At time t4, s_ctl becomes 1, the PWM controller on the secondary side does not operate, and the synchronous rectification controller on the secondary side operates. At this time, the MOS transistors TR1 AND TR2 on both sides of the primary AND secondary sides are both in an off state, the p_vds signal is maintained at a high level, the comparator p_comp3 outputs a low level, at this time, the voltage of the capacitor C1 gradually decreases to be below the threshold REF, the comparator p_comp1 outputs a rising edge signal, the Q terminal of the p_rs1 outputs a high level, AND the comparator p_comp2 has already outputted a high level at time t3, so that the AND gate p_and1 outputs a high level to control the PWM controller on the primary side to operate. I.e., p_ctl=0 is satisfied, and p_vds is high (secondary side PWM controller is not operated), the primary side PWM controller is operated.
Example two
The first bidirectional switching circuit or the second bidirectional switching circuit in the first embodiment is different from the first embodiment in that whether the opposite MOS transistor is in the on-off state is determined by detecting the average voltage of the transformer winding. In the second embodiment, whether the opposite MOS is in the on-off state is determined by detecting the edge signal of the transformer winding. The bidirectional switching circuit of the second embodiment is different from that of the first embodiment.
As shown in fig. 8, the first bidirectional switching circuit or the second bidirectional switching circuit of the present embodiment includes a first resistor R1, a second resistor R2, a counter, a second comparator COMP2, a first RS flip-flop RS1, a first NOT gate NOT1, AND a first AND gate AND1. The inverting input terminal of the second comparator COMP2 is used as the input terminal of the first bidirectional switching circuit 1 or the input terminal of the second bidirectional switching circuit 2, and the non-inverting input terminal of the second comparator COMP2 inputs the reference voltage REF. One end of the first resistor R1 is connected to one end of the first winding or one end of the second winding. The other end of the first resistor R1 is respectively connected with one end of the second resistor R2 and the reset input port RS of the counter. The other end of the second resistor R2 is connected to the ground gnd_p on the first winding side or the ground gnd_s on the second winding side. The clock input port CT of the counter inputs a set number of square wave signals CLK. The output end OUT of the counter is connected with the S end of the first RS trigger RS1, AND the output end of the second comparator COMP2 is respectively connected with one input end of the first AND gate AND1 AND the input end of the first NOT gate NOT 1. The output terminal of the first NOT1 is connected to the R terminal of the first RS flip-flop RS1, and outputs a synchronous rectification control signal SR_EN. The Q terminal of the first RS flip-flop RS1 is connected to the other input terminal of the first AND gate AND1. The output terminal of the first AND gate AND1 outputs the PWM control signal pwm_en.
The bidirectional switching circuit of the present embodiment operates on the principle that COMP2 outputs a high level signal when the control signal ctl=0, and the synchronous rectification control signal sr_en=0 controls the synchronous rectification controller to be inactive. When the opposite MOS transistor is still working, the VDS outputs a square wave signal. The RS end of the counter is a reset input port, and when a falling edge is received, the counter is controlled to reset, so that the output port OUT maintains a low level all the time. When the opposite MOS tube does not work, VDS will maintain high voltage, at this time, the RS port will not receive the reset signal all the time, when the clock input port CT receives the square wave signal of the set number, will control the output port OUT to output the high level, at this time, the first flip-flop RS1 will output the high level, AND gate AND1 outputs the high level, control PWM control work.
The connection relation and the operation principle of the circuits other than the bidirectional switching circuit in the embodiment, and the bidirectional equalization control method of the battery are the same as those in the first embodiment, and are not described here again.
Example III
In the third embodiment, the synchronous rectification controller in the first embodiment and the second embodiment is removed, and a diode D1 and a diode D2 are added between the drain and the source of the power transistor TR1 and the drain and the source of the power transistor TR2 as freewheeling diodes for reverse operation and forward operation, respectively. The bidirectional switching circuit can adopt the circuits of the embodiment 1 and the embodiment 2.
As shown in fig. 9, the first master 1 or the second master 2 includes a PWM controller, the first switching and rectifying device 1 includes a first MOS transistor TR1 and a first diode D1, and the second switching and rectifying device 2 includes a second MOS transistor TR2 and a second diode D2. The positive pole of first diode D1 is connected with the source electrode of first MOS pipe TR1, and the drain electrode of first MOS pipe TR1 is connected to the negative pole of first diode D1. The positive pole of second diode D2 is connected the source electrode of second MOS pipe TR2, and the drain electrode of second MOS pipe TR2 is connected to the negative pole of second diode D2.
The working principle is that during forward working, the MOS tube TR1 is conducted, the diode D1 does not work, and the MOS tube TR2 does not work. The MOS tube TR1 is used as a main MOS tube, and the diode D2 is used as a freewheeling diode to form a flyback circuit with primary side input and secondary side output. During reverse operation, the MOS transistor TR2 is turned on, the diode D2 does not operate, and the MOS transistor TR1 does not operate. The MOS tube TR2 is used as a main MOS tube, and the diode D1 is used as a freewheeling diode to form a flyback circuit with secondary side input and primary side output.
The synchronous rectification controller is omitted, the bidirectional switching circuit is not output of the synchronous rectification control signal SR_EN, and the connection relation and the working principle of other components and other circuit modules and the battery bidirectional equalization control method are the same as those of the first embodiment or the second embodiment. And are not described in detail herein.
Example IV
Unlike the first to third embodiments, in the fourth embodiment, the bidirectional switching circuit ensures that the PWM controllers of the primary and secondary sides do not operate simultaneously by delaying the operation of the PWM controllers. Rather than by a bi-directional switching circuit detecting the voltage of the transformer windings.
In one aspect, the method for controlling bidirectional equalization of a battery according to the present embodiment includes the following steps:
s1, a first bidirectional switching circuit and a signal isolation device receive an external control signal;
S2, if the control signal is a forward working signal, the first bidirectional switching circuit delays for a period of time, and then the first switch and the rectifying device are controlled to be conducted through the first main controller;
if the control signal is a reverse working signal, the first bidirectional switching circuit controls the first switch and the rectifying device to be turned off through the first main controller, and the signal isolation device inverts and outputs the control signal to the second bidirectional switching circuit to switch to S4;
S3, the second bidirectional switching circuit controls the second switch and the rectifying device to be turned off through the second main controller, and the S1 is returned;
s4, after the second bidirectional switching circuit delays for a period of time, the second switch and the rectifying device are controlled to be conducted through the second main controller, and the S1 is returned.
The control signal CTL controls the battery bidirectional equalization control circuit to operate in the forward direction or in the reverse direction. The control signal CTL may be a forward operation of the battery bidirectional equalization control circuit at a high level or a forward operation of the battery bidirectional equalization control circuit at a low level, and for convenience of description, the forward operation state of the battery bidirectional equalization control circuit is described by taking the CTL at a low level as an example, but the scope of protection of the present invention is not limited thereto.
The signal isolation device generally generates transmission delay due to the characteristics of the device itself, and delays for a period of time after receiving the control signal CTL, so as to output the inverted control signal, which is determined by the characteristics of the device itself. Of course, the requirements of the invention can be met without a delayed signal isolation device.
On the other hand, in the battery bidirectional equalization control circuit of the present embodiment, since the bidirectional switching circuit does not need to detect the voltage of the transformer winding, the connection relationship of the internal components of the bidirectional switching circuit is different from those of the first to third embodiments.
In the present embodiment, in the case where the main controller includes a PWM controller, the first bidirectional switching circuit 1 or the second bidirectional switching circuit 2 includes a fourth comparator COMP7, a fifth comparator COMP8, a fifth resistor R5, a first transistor Q1, and a second capacitor C2 as shown in fig. 11. The inverting input terminal of the fourth comparator COMP7 serves as the input terminal of the first bidirectional switching circuit 1 or the input terminal of the second bidirectional switching circuit 2, and the non-inverting input terminal of the fourth comparator COMP7 and the inverting input terminal of the fifth comparator COMP8 input the reference voltage REF. The output end of the fourth comparator COMP7 is connected to one end of the fifth resistor R5 and the base of the first triode Q1, respectively. The other end of the fifth resistor R5 is connected to the emitter of the first triode Q1, one end of the second capacitor C2 and the positive input end of the fifth comparator COMP8, respectively. The collector of the first transistor Q1 and the other end of the second capacitor C2 are connected to the ground gnd_p on the first winding side or the ground gnd_s on the second winding side. The output terminal of the fifth comparator COMP8 outputs the PWM control signal pwm_en to the PWM controller.
In the case where the main controller includes a PWM controller and a synchronous rectification controller, the first bidirectional switching circuit 1 or the second bidirectional switching circuit 2 includes a fourth comparator COMP7, a fifth comparator COMP8, a fifth resistor R5, a first transistor Q1, a second capacitor C2, and a second NOT gate NOT2, as shown in fig. 12. The inverting input terminal of the fourth comparator COMP7 serves as the input terminal of the first bidirectional switching circuit 1 or the input terminal of the second bidirectional switching circuit 2, and the non-inverting input terminal of the fourth comparator COMP7 and the inverting input terminal of the fifth comparator COMP8 input the reference voltage REF. The output end of the fourth comparator COMP7 is connected to one end of the fifth resistor R5, the base of the first triode Q1, and the input end of the second NOT gate NOT2, respectively. The output terminal of the second NOT2 outputs a synchronous rectification control signal SR_EN to the synchronous rectification controller. The collector of the first transistor Q1 and the other end of the second capacitor C2 are connected to the ground gnd_p on the first winding side or the ground gnd_s on the second winding side. The output terminal of the fifth comparator COMP8 outputs the PWM control signal pwm_en to the PWM controller.
The operation principle of the present embodiment in the case of including the synchronous rectification controller will be described with reference to fig. 13:
Before time t1, p_ctl=0, p_pwm_en=1, the primary side PWM controller is active, p_sr_en=0, the primary side synchronous rectification controller is inactive, s_ctl=1, p_pwm_en=0, the secondary side PWM controller is inactive, and s_sr_en=1 the secondary side synchronous rectification controller is active.
At time t1, p_ctl goes from 0 to 1, comparator p_com7 outputs a low level, and the voltage of capacitor p_c2 is pulled rapidly to 0V due to NPN transistor p_q1, at which time p_pwm_en=0, the primary PWM controller is not operating, and p_sr_en=1 synchronous rectification controller is operating. The secondary synchronous rectification controller works because of the transmission delay of the signal isolation device and the S_CTL is still kept to be 1. As can be seen from the description of the background art, the synchronous rectification controllers of the primary side and the secondary side do not cause reliability problems when the synchronous rectification controllers work simultaneously.
At time t2, s_ctl goes to 0, s_comp7 outputs a high level, s_c2 voltage slowly rises due to the resistor s_r3, the reference voltage REF is reached after a time delay, s_comp8 outputs a high level, and s_pwm_en=1 controls the PWM controller on the secondary side to operate. The delay function of the bidirectional switching circuit of the present embodiment is generated by charging the capacitor C2. The duration of the voltage of the capacitor C2 from 0 to the reference voltage REF is the delay of the bidirectional switching circuit. The delay can be controlled by adjusting the capacitance C2.
At time t3, p_ctl goes from 1 to 0, at which time p_comp7 outputs a high level, and the PWM controller on the primary side is not operating because the voltage on capacitor p_c2 slowly rises due to the presence of resistor p_r3, which has not yet reached threshold REF, and the output of p_comp8 remains low. Meanwhile, the NOT gate NOT2 outputs a low level, and P_SR_EN=0, so that synchronous rectification of the primary side is controlled to be NOT operated. Due to the delay of transmission, the s_ctl signal remains at 0, s_pwm_en=1, and the secondary PWM controller is still operating. Because of the delay effect of the P_C2 capacitor, the PWM controllers of the primary side and the secondary side cannot work simultaneously. The delay of C2 must be greater than the delay of the signal isolation device.
At time t4, s_ctl becomes 1, and similarly the capacitor voltage of s_c2 is rapidly pulled to 0, the secondary PWM controller does not operate, and sr_en=1 secondary synchronous rectification operates.
At time t5, the voltage of the capacitor p_c2 reaches the threshold REF, and the comparator p_comp8 outputs a high level to control the primary PWM controller to operate. In practical engineering application, enough time delay is set, so that the condition that the primary side PWM controller and the secondary side PWM controller work simultaneously can be avoided.
The above description is for the purpose of illustrating the embodiments of the present invention and is not to be construed as limiting the invention, but is intended to cover all modifications, equivalents, improvements and alternatives falling within the spirit and principles of the invention.