Disclosure of Invention
In view of the foregoing, it is desirable to provide a power supply board, a method of compensating for the accuracy of the power supply board, and a tester that can improve the accuracy of FI and MI.
The application provides a power panel card, which comprises a control module, a forward output channel module, a current measurement channel module, a voltage measurement channel module and a channel switching module, wherein the control module is connected with the forward output channel module, the current measurement channel module, the voltage measurement channel module and the channel switching module;
The control module is used for controlling the channel switching module to access the load when measuring the current, so that the forward output channel module outputs a test signal to the load, reads a current measurement value of the current measurement channel module and a voltage measurement value of the voltage measurement channel module, and performs measurement current compensation according to the read current measurement value, the voltage measurement value and preset compensation reference data to obtain compensated current;
The control module is also used for controlling the channel switching module to access the load when outputting current, so that the forward output channel module outputs current to the load according to a set current value, reads a current measurement value of the current measurement channel module and a voltage measurement value of the voltage measurement channel module, compensates the set current value according to the read current measurement value, the voltage measurement value and preset compensation reference data to obtain compensated set current, and controls the forward output channel module to output current according to the compensated set current;
and when the compensation reference data is the channel switching module is connected to a calibration module or the load, calculating according to the measurement data of the current measurement channel module and the voltage measurement channel module.
In one embodiment, the control module comprises a controller and a memory, wherein the controller is connected with the forward output channel module, the current measurement channel module, the voltage measurement channel module, the channel switching module and the memory, and when the controller controls the channel switching module to be connected with the calibration module or the load, measurement data of the current measurement channel module and the voltage measurement channel module are obtained and sent to an upper computer, and compensation reference data calculated by the upper computer according to the measurement data are received and stored in the memory.
In one embodiment, the forward output channel module includes a digital-to-analog conversion module U5 and a gain programmable power amplifier module U6, where the digital-to-analog conversion module U5 is connected to the control module and the gain programmable power amplifier module U6, and the gain programmable power amplifier module U6 is connected to the current measurement channel module.
In one embodiment, the current measurement channel module includes an analog-to-digital conversion module U2, a gain programmable operational amplifier module U3, a subtracter U4, and a gear adjusting circuit, where the gear adjusting circuit is connected to the forward output channel module, the channel switching module, and the control module, the subtracter U4 is connected to the gear adjusting circuit and the gain programmable operational amplifier module U3, and the analog-to-digital conversion module U2 is connected to the gain programmable operational amplifier module U3 and the control module.
In one embodiment, the voltage measurement channel module includes an analog-to-digital conversion module U7, a gain programmable operational amplification module U8, and a subtractor U9, where the subtractor U9 is connected to the channel switching module and the gain programmable operational amplification module U8, and the analog-to-digital conversion module U7 is connected to the gain programmable operational amplification module U8 and the control module.
In one embodiment, the channel switching module comprises a switch HF, a switch LF, a switch HS, a switch LS, a switch K1, a switch K2, a switch K3, a switch K4 and a switch K5, wherein a first end of the switch K1 is connected with the current measuring channel module and a static contact of the switch HF, a second end of the switch K1 is connected with the voltage measuring channel module and the first end of the switch K4, a first movable contact of the switch HF is connected with the first end of the calibration module, a second movable contact of the switch HF is connected with the first end of the load, a second end of the switch K4 is connected with the first end of the switch K3 and a static contact of the switch HS, a first movable contact of the switch HS is connected with the first end of the calibration module, a second movable contact of the switch HS is connected with the first end of the voltage measuring channel module and the first end of the switch K5, a second end of the switch K2 is connected with the ground end of the static contact of the switch LS, a second movable contact of the switch LS is connected with the second end of the switch LS, and a second movable contact of the switch LF is connected with the second end of the calibration module.
The second aspect of the present application provides a method for compensating accuracy of a power board, including:
When measuring current, the control channel switching module is connected to a load, so that the forward output channel module outputs a test signal to the load, a current measurement value of the current measurement channel module and a voltage measurement value of the voltage measurement channel module are read, and measurement current compensation is carried out according to the read current measurement value, the voltage measurement value and preset compensation reference data, so that compensated current is obtained;
When outputting current, controlling the channel switching module to access the load, enabling the forward output channel module to output current to the load according to a set current value, reading a current measurement value of the current measurement channel module and a voltage measurement value of the voltage measurement channel module, compensating the set current value according to the read current measurement value, the voltage measurement value and preset compensation reference data to obtain compensated set current, and controlling the forward output channel module to output current according to the compensated set current;
and when the compensation reference data is the channel switching module is connected to a calibration module or the load, calculating according to the measurement data of the current measurement channel module and the voltage measurement channel module.
In one embodiment, the measuring current compensation is performed according to the read current measurement value, the voltage measurement value and the preset compensation reference data to obtain a compensated current, and the method comprises the steps of calculating a common-mode voltage according to the current measurement value, the voltage measurement value, the high-end line resistance and the low-end line resistance;
And/or
The method comprises the steps of obtaining a common-mode voltage according to current measurement values, voltage measurement values, high-end line resistances and low-end line resistances, and obtaining the compensated set current according to the set current values, the common-mode voltage, compensation coefficients and measuring range coefficients.
In one embodiment, the compensation reference data includes a compensation coefficient, a span coefficient, a high-side line resistance, and a low-side line resistance.
In one embodiment, the method further comprises:
controlling the channel switching module to be connected to the calibration module, enabling the forward output channel module to output voltage points uniformly distributed in a maximum voltage range, and reading current data at each voltage point through the current measurement channel module;
And calculating a compensation coefficient according to the voltage points and the current data read by each voltage point.
In one embodiment, the method further comprises:
Controlling the channel switching module to access a load, so that the forward output channel module outputs a set current, and obtaining the measurement voltage of the voltage measurement channel module;
And calculating to obtain high-end line resistance and low-end line resistance according to the set current and the measured voltage.
In one embodiment, the span coefficient is calculated according to the maximum values of different spans of the current measurement channel module and the corresponding gains.
In one embodiment, the method further comprises calibrating the accuracy of each current range when the channel switching module is controlled to be connected to the calibration module.
The third aspect of the application provides a testing machine, which comprises an upper computer and the power panel card.
The control module is used for controlling the channel switching module to be connected with a load when measuring current, so that the forward output channel module outputs a test signal to the load, reads a current measurement value of the current measurement channel module and a voltage measurement value of the voltage measurement channel module, and performs measurement current compensation according to the read current measurement value, the voltage measurement value and preset compensation reference data to obtain compensated current. The control module is used for controlling the channel switching module to be connected with a load when outputting current, so that the forward output channel module outputs current to the load according to the set current value, reads the current measured value of the current measuring channel module and the voltage measured value of the voltage measuring channel module, compensates the set current value according to the read current measured value, the voltage measured value and preset compensation reference data to obtain compensated set current, and controls the forward output channel module to output current according to the compensated set current. When the current and the output current are measured, and the calibration module or the load is accessed through the channel switching module, compensation reference data is obtained by calculation according to the measurement data of the current measurement channel module and the voltage measurement channel module, and the current compensation is performed by combining the compensation reference data, so that the FI and MI precision of the power supply board card is improved.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It is to be understood that in the following embodiments, "connected" is understood to mean "electrically connected", "communicatively connected", etc., if the connected circuits, modules, units, etc., have electrical or data transfer between them.
As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," and/or the like, specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof.
In one embodiment, as shown in fig. 1, a power board is provided, which includes a control module 110, a forward output channel module 120, a current measurement channel module 130, a voltage measurement channel module 140, and a channel switching module 150, where the control module 110 is connected to the forward output channel module 120, the current measurement channel module 130, the voltage measurement channel module 140, and the channel switching module 150, the forward output channel module 120 is connected to the current measurement channel module 130, and the channel switching module 150 is connected to the current measurement channel module 130, the voltage measurement channel module 140, and the load RLOAD. The control module 110 is configured to, when measuring a current, control the channel switching module 150 to access the load RLOAD, make the forward output channel module 120 output a test signal to the load RLOAD, read a current measurement value of the current measurement channel module 130 and a voltage measurement value of the voltage measurement channel module 140, and perform measurement current compensation according to the read current measurement value, the voltage measurement value and preset compensation reference data, thereby obtaining a compensated current. The control module 110 is further configured to, when outputting a current, control the channel switching module 150 to access the load RLOAD, enable the forward output channel module 120 to output the current to the load RLOAD according to the set current value, read the current measurement value of the current measurement channel module 130 and the voltage measurement value of the voltage measurement channel module 140, compensate the set current value according to the read current measurement value, the voltage measurement value and the preset compensation reference data to obtain a compensated set current, and control the forward output channel module 120 to output the current according to the compensated set current.
When the compensation reference data is the measurement data of the current measurement channel module 130 and the voltage measurement channel module 140 when the channel switching module 150 accesses the calibration module 210 or the load RLOAD, the compensation reference data is calculated. The type of compensation reference data is not unique and may include, for example, compensation coefficients, high-side resistances, low-side resistances, and the like. The calibration module 210 includes a programmable resistor network for calibration and a high-precision voltage measurement module that can be used to measure voltage and current. The control module 110 is connected with the relevant switch in the channel switching module 150 to perform switching control on the channel switching module 150, and the compensation reference data is determined and stored in combination with the collected measurement data. It should be noted that the compensation reference data may be calculated by the control module 110 in combination with the measurement data and stored, or the control module 110 may upload the obtained measurement data to an upper computer, calculate the compensation reference data by the upper computer, and then send the compensation reference data to the control module 110 for storage. In practical application, when the power panel card is required to measure current or output current, current compensation is carried out by combining compensation reference data, so that the common mode influence is eliminated, the FI and MI precision of the power panel card is improved, an additional common mode error compensation hardware circuit is not required, and the precision compensation cost is low.
Specifically, as shown in fig. 2, the control module 110 includes a controller U1 and a memory U10, and the controller U1 connects the forward output channel module 120, the current measurement channel module 130, the voltage measurement channel module 140, the channel switching module 150, and the memory U10. When the controller U1 controls the channel switching module 150 to access the calibration module 210 or the load RLOAD, measurement data of the current measurement channel module 130 and the voltage measurement channel module 140 are obtained and sent to the upper computer 220, and compensation reference data obtained by calculation of the upper computer 220 according to the measurement data is received and stored in the memory U10. The controller U1 may be an FPGA (Field-Programmable gate array) or other type of control unit and the memory U10 may be a FLASH memory unit or other type of memory.
In one embodiment, as shown in fig. 2, the forward output channel module 120 includes a digital-to-analog conversion module U5 and a gain programmable power amplifier module U6, where the digital-to-analog conversion module U5 is connected to the control module 110 and the gain programmable power amplifier module U6, and the gain programmable power amplifier module U6 is connected to the current measurement channel module 130.
Specifically, the digital-to-analog conversion module U5 is connected to the controller U1, and the controller U1 can control the forward output channel module 120 to output voltage or current. When the forward output channel module 120 works in the voltage output mode, the controller U1 takes the difference value between the voltage Measurement (MV) value and the set voltage value of the voltage measurement channel module 140 as an error, adjusts the forward channel output by using a PID control algorithm to realize the function of stabilizing the output voltage, and when the forward output channel module 120 works in the current output mode, the controller U1 takes the difference value between the current Measurement (MI) value and the set current value of the current measurement channel module 130 as an error, and adjusts the forward channel output by using a PID control algorithm to realize the function of stabilizing the output current.
With continued reference to fig. 2, the current measurement channel module 130 may include an analog-to-digital conversion module U2, a gain programmable operational amplifier module U3, a subtractor U4, and a gear adjustment circuit 132, where the gear adjustment circuit 132 is connected to the forward output channel module 120, the channel switching module 150, and the control module 110, the subtractor U4 is connected to the gear adjustment circuit 132 and the gain programmable operational amplifier module U3, and the analog-to-digital conversion module U2 is connected to the gain programmable operational amplifier module U3 and the control module 110.
Specifically, the gear adjusting circuit 132 and the analog-to-digital conversion module U2 are both connected to the controller U1, and the controller U1 controls the gear adjusting circuit 132 to perform current range gear adjustment, and receives the current measurement value output by the analog-to-digital conversion module U2. The current measurement principle is that after the voltage difference is calculated by the subtracter U4, the voltage at two ends of the sampling resistor in the gear adjusting circuit 132 is conditioned by the gain programmable operational amplifier module U3 to the usable voltage range of the analog-digital conversion module U2, the voltage is converted into digital quantity by the analog-digital conversion module U2 and sent to the controller U1, and the current measurement value is output by the controller U1 and returned to the upper computer 220. When the current is measured in practical application, the controller U1 obtains the current measured value according to the digital quantity output by the analog-to-digital conversion module U2, then combines the voltage measured value and the compensation reference data to carry out measurement current compensation, and the obtained compensated current value is sent to the upper computer 220 for data analysis by the upper computer 220.
The gear adjusting circuit 132 may support 2 or more current range gear adjustments, in this embodiment, the gear adjusting circuit 132 has three current range gears, including a sampling resistor R1, a sampling resistor R2, and a sampling resistor R3, where after the sampling resistor R1, the sampling resistor R2, and the sampling resistor R3 are respectively connected in series with corresponding control switches, the other end of each sampling resistor is connected to the input terminal of the subtractor U4—and the gain programmable power amplifier module U6, and the other end of each control switch is connected to the input terminal+ of the subtractor U4 and the channel switching module 150. The control switch can be a relay or other types of controlled switches, the resistance values of the sampling resistor R1, the sampling resistor R2 and the sampling resistor R3 can be designed to be different from each other, the controller U1 is connected with the control end of each control switch, the control switch is switched and controlled, and different sampling resistors are connected into a circuit to realize the adjustment of the current range and the gear. For example, the sampling resistor R1, the sampling resistor R2, and the sampling resistor R3 respectively correspond to the current ranges from small to large, and the current ranges can be adjusted by adjusting the connection and disconnection of the sampling resistor R1, the sampling resistor R2, and the sampling resistor R3.
In one embodiment, the voltage measurement channel module 140 includes an analog-to-digital conversion module U7, a gain programmable operational amplification module U8, and a subtractor U9, the subtractor U9 connecting the channel switching module 150 and the gain programmable operational amplification module U8, and the analog-to-digital conversion module U7 connecting the gain programmable operational amplification module U8 and the control module 110. The analog-digital conversion module U7 is specifically connected to the controller U1, and the voltage measurement principle is that the voltage between the input end+ and the input end-of the subtracter U9 is regulated to the usable range of the analog-digital conversion module U7 through the gain programmable operational amplification module U8 after the voltage difference is determined by the subtracter U9, the voltage difference is converted into digital quantity through the analog-digital conversion module U7 and sent to the controller U1, and the voltage measurement value is returned to the upper computer 220 by the controller U1. When the compensation reference data is analyzed, the controller U1 obtains a voltage measurement value according to the digital quantity output by the analog-to-digital conversion module U7, and sends the voltage measurement value to the upper computer 220 to calculate and determine the compensation reference data by the upper computer 220, and when the voltage is measured in practical application, the controller U1 can also obtain the voltage measurement value according to the digital quantity output by the analog-to-digital conversion module U7, then perform voltage compensation, and send the compensated voltage value to the upper computer 220 to perform data analysis by the upper computer 220.
Furthermore, the channel switching module 150 may specifically include a switch HF, a switch LF, a switch HS, a switch LS, a switch K1, a switch K2, a switch K3, a switch K4, and a switch K5, wherein a first end of the switch K1 is connected to the current measurement channel module 130 and a stationary contact of the switch HF, specifically connected to each control switch in the current measurement channel module 130 and an input terminal+ of the subtractor U4, and a second end of the switch K1 is connected to a first end of the voltage measurement channel module 140 and the switch K4, specifically connected to an input terminal+ of the subtractor U9 in the voltage measurement channel module 140. The first movable contact of the switch HF is connected with the first end of the calibration module 210, the second movable contact of the switch HF is connected with the first end of the load RLOAD, the second end of the switch K4 is connected with the first end of the switch K3 and the fixed contact of the switch HS, the first movable contact of the switch HS is connected with the first end of the calibration module 210, the first end of the switch K2 is connected with the first ends of the voltage measurement channel module 140 and the switch K5, in particular, the second end of the switch K2 is connected with the ground end of the subtractor U9 in the voltage measurement channel module 140 and the fixed contact of the switch LF, the first movable contact of the switch LF is connected with the second end of the calibration module 210, the second movable contact of the switch LF is connected with the second end of the load RLOAD, the second end of the switch K5 is connected with the second end of the switch K3 and the fixed contact of the switch LS, the first movable contact of the switch LS is connected with the second end of the calibration module 210, and the second movable contact of the switch LS is connected with the second end of the load RLOAD. The switches HF, LF, HS, LS, K1, K2, K3, K4 and K5 may be relays or other types of controlled switches, where the controller U1 is connected to a control end of each switch, and controls on/off of each switch to perform kelvin (kelvin) detection.
Further, the control module 110 is further configured to calibrate the accuracy of each current range when the channel switching module 150 accesses the calibration module 210. The accuracy of each current measurement range of the current measurement channel module 130 can be calibrated in a low voltage (+ -Vcal) range, calibration parameters of each current measurement range are obtained and stored, and the voltage and current full-scale values are Vcal and Ical respectively. The calibration parameters may specifically include gain and offset, and in practice, the control module 110 performs current output and current measurement according to the stored calibration parameters to ensure accuracy of the current output and current measurement. For example, when calculating compensation reference data (e.g., compensation coefficient, etc.), the accuracy of current measurement can be improved by collecting the required current measurement data through the current measurement channel module 130 after performing the range accuracy calibration at a low voltage, thereby ensuring that accurate compensation reference data is obtained. In addition, when the power board operates in the current measurement or output current mode, the current measurement channel module 130 can be ensured to acquire an accurate current measurement value, and then the compensation reference data is combined to perform corresponding compensation processing.
The calibration may be performed on the accuracy of each current range, after the control channel switching module 150 accesses the calibration module 210, the forward output channel module 120 outputs voltage points uniformly distributed in the low voltage range, and reads current data at each voltage point through the current measurement channel module 130, and calculates calibration parameters of each current range according to the current data and the corresponding current expected value.
As shown in fig. 2, an instruction can be sent to the controller U1 through the upper computer 220, the controller U1 directly controls the switch K1, the switch K2 and the switch K3 to be opened, the switch K4 and the switch K5 to be closed, controls the switch HF, the switch LF, the switch HS and the switch LS to be cut to the calibration module 210, the sampling resistor R1 to be closed, and selects a proper load resistor in the calibration module 210Setting the working mode of the channel as FVMI, sequentially outputting N uniformly distributed voltage points (V1,V2,…,VN) in + -Vcal through FV, reading M pieces of current data through MI function at each voltage point, checking the M pieces of current data by using golbus algorithm, removing points with larger deviation degree, taking the average value of the rest data as the measured value of the current, and sequentially collecting the measured values of the N voltage points (Imeas1,Imeas2,…,ImeasN). The calibration module 210 measures the actual current values of the programmable resistor network for calibration by using the high-precision voltage measurement module inside the calibration module 210 by using the same method as MI, and the corresponding N actual currents (Iact1,Iact2,…,IactN) are measured as the current expected values, and the upper computer 220 calculates the calibration parameters as the formulas (1-1) and (1-2) by using the least square method.
(1-1)
(1-2)
Sequentially repeating the current measuring ranges corresponding to all the sampling resistors to perform precision calibration to obtain the calibration parameters of the corresponding measuring range MI, wherein the calibration parameters of FI are as follows,. In addition, the same method can be used for calibrating and obtaining the calibration parameters of the corresponding measuring ranges FV and MV. The calibration parameters include gain and offset, and the upper computer 220 sends the calculated gain and offset parameters for each range to the controller U1 and stores them in the memory U10. Further, the upper computer 220 may also encode the gain and the offset, and send the encoded data and the CRC checksum to the controller U1, and store the encoded data and the CRC checksum in the memory U10.
In one embodiment, the compensation reference data includes a compensation coefficient Kcm. The control module 110 may control the channel switching module 150 to access the calibration module 210, so that the forward output channel module 120 outputs voltage points uniformly distributed in the maximum voltage range, and reads current data from each voltage point through the current measurement channel module 130. Then, the upper computer 220 calculates a compensation coefficient Kcm according to the voltage points and the current data read by each voltage point. Specifically, the process of measuring and calculating the compensation coefficient Kcm using FVMI in the maximum voltage range is as follows:
As shown in fig. 2, the upper computer 220 sends a command to the controller U1, the controller U1 directly controls the switch K1 and the switch K2 to be closed, the switch K3 to be opened, the switch K4 and the switch K5 to be closed, the switch HF, the switch LF, the switch HS and the switch LS to be cut to the calibration module 210, the maximum current range gear (the sampling resistor R3 is connected) is selected, the calibration module 210 circuit is not loaded, the channel working mode is FVMI mode, N uniformly distributed voltage points (V1,V2,…,VN) in the maximum voltage range are output by FV, M current data are read at each voltage point through MI function, M current data are checked by using golbus algorithm, the point with larger deviation degree is removed, the residual current data is averaged to be used as the measured value of current, the current values (Imeas1,Imeas2,…,ImeasN) of N voltage points are sequentially obtained, and the compensation coefficient Kcm is calculated by the upper computer 220 by using the least square method as (1-3).
(1-3)
The compensation coefficient Kcm is transmitted to the controller U1 by the host computer 220 and stored in the memory U10. Further, the upper computer 220 may also encode the compensation coefficient Kcm, send the encoded data and the CRC checksum to the controller U1, and store the encoded data and CRC checksum in the memory U10.
In one embodiment, the compensation reference data includes a span factor Ktap, and the span factor Ktap may be calculated based on the maximum values of the different spans of the current measurement channel module 130 and the corresponding gains.
As shown in fig. 2, a measurement range coefficient Ktap can be calculated according to the MI measurement range and the signal conditioning ratio, the gain between the sampling resistor R (R1/R2/R3) and the analog-to-digital converter U2 is G (G1/G2/G3), the maximum value of the measurement range is Imax (Imax 1/Imax2/Imax 3), and the measurement range coefficient Ktap is shown as formula (1-4), where i corresponds to different current measurement ranges.
(1-4)
The upper computer 220 transmits the span coefficient Ktap to the controller U1 and stores it in the memory U10. Further, the upper computer 220 may also encode the span coefficient Ktap, send the encoded data and the CRC checksum to the controller U1, and store the encoded data and CRC checksum in the memory U10.
In one embodiment, the compensated reference data includes a high-side resistor RH and a low-side resistor RL. The control module 110 may control the channel switching module 150 to access the load RLOAD, so that the forward output channel module 120 outputs a set current, and obtains the measured voltage of the voltage measurement channel module 140. Then, the upper computer 220 calculates the high-end resistor RH and the low-end resistor RL according to the set current and the measured voltage.
Specifically, the high-side resistance RH and the low-side resistance RL can be measured and calculated using FIMV in the low-voltage (±vcal) range of the range accuracy calibration. The measured voltages may include a first measured voltage Vl and a second measured voltage Vh, which are used as the corresponding calculated low-side resistances RL and Gao Duanxian, respectively, RH. As shown in fig. 2, the upper computer 220 sends an instruction to the controller U1, the controller U1 directly controls the switch K1, the switch K2, the switch K3 and the switch K5 to be closed, the switch K4 to be opened, controls the switch HF and the switch HS to be switched to the load RLOAD, selects the mA level current range, sets the working mode as FIMV, the FI output setting current I as 1mA, uses MV functional test to obtain the second measurement voltage Vh, calculates the high-end line resistance RH =vh/I, controls the switch K1, the switch K2, the switch K3 and the switch K4 to be closed, controls the switch K5 to be opened, controls the switch LS and the switch LF to be switched to the load RLOAD (the switch HF and the switch HS to be switched off may be kept open, in this embodiment, the switch HF and the switch HS to be switched off are used as an example to be described), uses MV functional test to obtain the first measurement voltage Vl, and calculates the low-end line resistance RL =vl/I. The upper computer 220 sends the high-side resistor RH and the low-side resistor RL to the controller U1 and stores them in the memory U10. Similarly, the upper computer 220 may also encode the high-side resistor RH and the low-side resistor RL, send the encoded data and the CRC checksum to the controller U1, and store the encoded data and CRC checksum in the memory U10.
The manner in which the control module 110 performs current compensation in conjunction with the compensation reference data is not unique when the current or output current is required to be measured in actual use after the compensation reference data is stored. In one embodiment, when measuring current, the control module 110 calculates a common mode voltage based on the current measurement, the voltage measurement, the high side line resistance and the low side line resistance, and calculates a compensated current based on the current measurement, the common mode voltage, the compensation coefficient and the span coefficient.
Specifically, when measuring the current, the control module 110 simultaneously measures the voltage and the current, and calculates the compensated current by combining the high-end and low-end resistances, the span coefficient and the compensation coefficient, thereby improving the MI accuracy. As shown in fig. 2, the upper computer 220 sends an instruction to the controller U1, the controller U1 directly controls the switch K1, the switch K2 and the switch K3 to be opened, the switch K4 and the switch K5 to be closed, controls the switch HF, the switch LF, the switch HS and the switch LS to be switched to the load RLOAD, the sampling resistor Ri to be closed (switched to the current range of the practical application), the voltage and current full range values are Vcal and Ical respectively, the channel working mode is FXMI mode, the FI or FV is controlled to be output in the range, the controller U1 or the upper computer 220 reads the voltage measurement value Vdut and the current measurement value Ioriginal, and the common mode voltage Vcm is calculated as shown in (1-5).
(1-5)
The compensated current Imeas is shown in the formula (1-6).
(1-6)
Further, when outputting current, the control module 110 calculates a common-mode voltage according to the current measurement value, the voltage measurement value, the high-end line resistance and the low-end line resistance, and calculates a compensated set current according to the set current value, the common-mode voltage, the compensation coefficient and the measuring range coefficient. After obtaining the compensated set current, the control module 110 controls the forward output channel module to output current according to the compensated set current, for example, the compensated set current is used as a new set value, and the difference between the measured current value and the new set value is used as an error, and the forward channel output is adjusted by using a PID control algorithm, so that the FI accuracy is improved.
Specifically, when outputting current, the control module 110 measures voltage and current simultaneously, and calculates a compensated set value by combining the high-end resistance and the low-end resistance, the measuring range coefficient and the compensation coefficient. As shown in fig. 2, the upper computer 220 sends an instruction to the controller U1, the controller U1 directly controls the switch K1, the switch K2 and the switch K3 to be opened, the switch K4 and the switch K5 to be closed, controls the switch HF, the switch LF, the switch HS and the switch LS to be switched to the load RLOAD, the sampling resistor Ri to be closed (switched to the current range of the practical application), sets the channel working mode to be FIMX mode, controls the FI to output a set current value Iset in the range, and the controller U1 circularly reads the voltage measurement value Vdut and the current measurement value Ioriginal, and calculates the common mode voltage Vcm as shown in formulas (1-7).
(1-7)
The compensated set current I is shown in the formula (1-8).
(1-8)
In one embodiment, as shown in fig. 3, there is further provided a method for compensating accuracy of a power board, including:
And step S110, when the current is measured, the control channel switching module is connected to the load, so that the forward output channel module outputs a test signal to the load, the current measurement value of the current measurement channel module and the voltage measurement value of the voltage measurement channel module are read, and the current compensation is performed according to the read current measurement value, the voltage measurement value and preset compensation reference data, so that the compensated current is obtained.
And step S120, when outputting current, the control channel switching module is connected to a load, so that the forward output channel module outputs current to the load according to the set current value, reads the current measurement value of the current measurement channel module and the voltage measurement value of the voltage measurement channel module, compensates the set current value according to the read current measurement value, the voltage measurement value and preset compensation reference data to obtain compensated set current, and controls the forward output channel module to output current according to the compensated set current.
When the channel switching module is connected to the calibration module or the load, the compensation reference data is obtained by calculation according to the measurement data of the current measurement channel module and the voltage measurement channel module. The compensation reference data may include, in particular, compensation coefficients, span coefficients, high-end resistances, and low-end resistances. And calculating the measuring range coefficient according to the maximum values of different measuring ranges of the current measuring channel module and the corresponding gains.
In one embodiment, the step S110 of measuring the current compensation according to the read current measurement value, voltage measurement value and preset compensation reference data to obtain the compensated current includes calculating a common-mode voltage according to the current measurement value, voltage measurement value, high-end line resistance and low-end line resistance, and calculating the compensated current according to the current measurement value, the common-mode voltage, the compensation coefficient and the span coefficient.
In one embodiment, the step S120 of compensating the set current value according to the read current measurement value, voltage measurement value and preset compensation reference data to obtain a compensated set current includes calculating a common-mode voltage according to the current measurement value, voltage measurement value, high-end line resistance and low-end line resistance, and calculating a compensated set current according to the set current value, the common-mode voltage, compensation coefficient and span coefficient.
In one embodiment, the method further comprises the steps of controlling the channel switching module to be connected to the calibration module, enabling the forward output channel module to output voltage points which are evenly distributed in the maximum voltage range, reading current data at each voltage point through the current measurement channel module, and calculating compensation coefficients according to the voltage points and the current data read by each voltage point.
In one embodiment, the method further comprises the steps of controlling the channel switching module to access a load, enabling the forward output channel module to output a set current, obtaining a measurement voltage of the voltage measurement channel module, and calculating to obtain the high-end line resistance and the low-end line resistance according to the set current and the measurement voltage.
In one embodiment, the method further comprises calibrating the accuracy of each current range when the control channel switching module is connected to the calibration module.
It can be appreciated that, the specific embodiments of the method for compensating the accuracy of the power board are explained in detail in the power board, and are not described herein again.
In an embodiment, a testing machine is further provided, including an upper computer and the power board.
As shown in fig. 4, in the precision compensation method of the power board provided by the application, the measured value of the current is calibrated under the condition of low voltage (+ -Vcal), and the full-scale values of the voltage and the current corresponding to the calibration are Vcal and Ical respectively. Then measuring and calculating a compensation coefficient Kcm under an empty load condition through FVMI function, calculating a measurement range coefficient Ktap according to a current range and a signal conditioning proportion on hardware, and measuring and calculating Gao Duanxian resistance RH and low-end resistance RL under the same voltage and current condition as the calibration through FIMV function of the board card when the connecting line of the tester changes each time. Finally, when measuring current, voltage and current Ioriginal are measured simultaneously, and the common-mode voltage Vcm is calculated by combining the high-end line resistance RH and the low-end line resistance RL and calibrating the full-scale values Vcal and Ical, then the compensated measured current valueWhen outputting current, the control loop continuously compensates the set value according to the measured voltage. After compensation, the current output and the measurement precision can be kept consistent with the calibration precision in a larger voltage range. According to the scheme, the compensation coefficient is calculated only at the maximum current range, other current ranges can be used through the range coefficient, and the efficiency is improved. And the line resistance is taken into consideration when compensation calculation is performed, so that the compensation precision is improved. In the calculation process of the calibration parameters and the compensation coefficients, each data point uses a test function to filter the data with larger deviation degree, and the stability of the calibration parameters and the compensation coefficients is improved by the method of averaging the residual data.
The precision compensation method of the power panel card has the following advantages:
1. the compensated current output and the current measurement have higher precision in the full voltage range.
2. The compensation coefficient is measured and calculated only in the maximum current range, and other current ranges can be used through the range coefficient.
3. The influence of the line resistance during actual test is considered, and particularly under the condition of larger current, the compensation precision is higher.
4. The compensation factor is valid for both current output and current measurement.
5. The compensation process can be based on a hardware functional module of the power panel card, and a new common mode error compensation hardware circuit is not required to be added.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.