CN113156192A - Current sampling device of high-voltage system of new energy vehicle - Google Patents
Current sampling device of high-voltage system of new energy vehicle Download PDFInfo
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- CN113156192A CN113156192A CN202110215597.1A CN202110215597A CN113156192A CN 113156192 A CN113156192 A CN 113156192A CN 202110215597 A CN202110215597 A CN 202110215597A CN 113156192 A CN113156192 A CN 113156192A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/32—Compensating for temperature change
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Abstract
The invention discloses a current sampling device of a high-voltage system of a new energy vehicle, which comprises a sampling resistor, a control and compensation module, a sampling chip, a power supply module and an interface, wherein the sampling resistor is connected to the sampling chip, the sampling chip is used for collecting the voltage of the sampling resistor, the control and compensation module is connected with the sampling chip and the interface, the control and compensation module is used for receiving the voltage of the sampling resistor and the temperature-sensitive resistor resistance value of the sampling chip, the control and compensation module is used for calculating by adopting compensation parameters according to the voltage of the sampling resistor and the temperature-sensitive resistor resistance value to obtain sampling current and outputting the sampling current, and the power supply module is used for supplying power to the control and compensation module and the sampling chip. According to the invention, the control and compensation module calculates and calibrates the sampling current by using the compensation parameter, so that the measurement deviation caused by the temperature rise of the sampling resistor and the temperature rise of the chip is overcome, and the current sampling precision is improved.
Description
Technical Field
The invention relates to a current sampling device, in particular to a current sampling device of a high-voltage system of a new energy vehicle.
Background
With the development and popularization of new energy automobile technology, people increasingly demand the management of electrical energy inside new energy automobiles, and the demand is concentrated on the demand of direct current sensing precision of components such as a Battery Management System (BMS), an Inverter (INV) and the like. The current new energy automobile current sensor technology mainly comprises a Hall type current sensor and a shunt type current sensor. The current divider based on ohm's law is used for sampling direct current of the current divider, a high-precision sampling resistor is connected in series in a circuit, voltage values generated at two ends of the sampling resistor are detected, a current value passing through the sampling resistor, namely a current value in a tested circuit, is obtained according to I-U/R, wherein R is a resistance value of the sampling resistor, I is the tested current, and U is the voltage value at two ends of the sampling resistor.
In general, a sample resistor generates heat when a current to be measured flows through the sample resistor, and the actual resistance value changes under the influence of temperature, so that the calculation of the current to be measured is influenced. Meanwhile, the voltage sampling analog-to-digital conversion chip in the sensor and the microcontroller chip parameters can also change along with the temperature, so that the accuracy of the current sensor is insufficient. Taking the high-voltage battery management system BMS of the new energy vehicle as an example, the accuracy of the charging and discharging current value of the battery to the vehicle system directly affects the calculation of the charging and discharging energy of the battery to itself and the evaluation of the residual energy. The new energy vehicle may experience wide temperature change and large current change range in the running process, the traditional current sensor has single sampling signal, and if the sampling signal is calculated and processed by fixed calibration parameters, the sampling precision is affected when the consistency of sampling elements or chip products is low.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a current sampling device of a high-voltage system of a new energy vehicle, and solves the problems of low sensing precision, large influence of temperature, non-linearity of current detection and the like of a direct current sensor technology used in the new energy vehicle.
The technical scheme of the invention is as follows: the utility model provides a new energy car high voltage system's current sampling device, includes sampling resistor, control and compensation module, sampling chip, power module and interface, sampling resistor connect in sampling chip by sampling chip gathers sampling resistor's voltage, control and compensation module connect sampling chip with the interface, control and compensation module receive sampling resistor's voltage and sampling chip's temperature sensing resistance, control and compensation module basis sampling resistor's voltage temperature sensing resistance adopts the compensation parameter to calculate and obtain sampling current and output, power module does control and compensation module with sampling chip supplies power.
Furthermore, the control and compensation module is provided with a temperature sensing resistor, the control and compensation module obtains a self temperature signal according to the temperature sensing resistor, and the voltage of the sampling resistor, the resistance value of the temperature sensing resistor and the self temperature signal are obtained according to the sampling resistor when the compensation parameter is adopted for calculating and obtaining the sampling current.
Further, the control and compensation module obtains a reference voltage value of the sampling chip, and the compensation parameter is adopted to calculate to obtain the sampling current according to the voltage of the sampling resistor, the resistance value of the temperature sensing resistor, the reference voltage value and the self temperature signal.
Further, the reference voltage value is not less than two.
And the CAN communication module is electrically connected with the control and compensation module and sends signals to the outside through the interface.
Compared with the prior art, the invention has the advantages that:
the invention eliminates the inconsistency caused by the chip or sampling resistor manufacturing process by detecting most parameters influencing the detection current precision and through test and calibration, customizes a calibration parameter set for the current sensor by considering the influence of temperature on the sampling chip and the sampling resistor, eliminates the errors in expectation and non-expectation by regression calculation, and realizes the maximum precision improvement.
Drawings
Fig. 1 is a schematic block diagram of a current sampling device of a high-voltage system of a new energy vehicle according to an embodiment.
Fig. 2 is a schematic diagram of a calibration system module for calibrating a current sampling device of a high-voltage system of a new energy vehicle.
Fig. 3 is a reference current error diagram of a sampling current of a current sampling device of a high-voltage system of a new energy vehicle and a test platform.
Detailed Description
The present invention is further illustrated by the following examples, which are not to be construed as limiting the invention thereto.
As shown in fig. 1, the current sampling device of the high-voltage system of the new energy vehicle according to the embodiment of the present invention mainly includes two parts, namely, a high-precision shoot sampling resistor 1, and a current sensor sampling control circuit a including a control and compensation module 2, a sampling chip 3, a CAN communication module 4, a power supply module 5, an interface 6, and other peripheral resistors.
A PCB of the control circuit A is tightly attached and installed with a Shunt sampling resistor 1 through welding, voltage sampling points of the sampling resistor 1 are arranged on the edges of the left side and the right side of the spatial position of the control circuit A, and voltage values on the two sides of the sampling resistor are obtained through a sampling chip 3.
The control circuit A is powered by an external power supply Uin, taking a mainstream energy passenger vehicle as an example, and the rated voltage is 12V. The control circuit internal power supply module 5 converts an external power supply into the internal control and compensation module 2, the sampling chip 3 and the communication module 4 for power supply and provides a reference voltage value.
The sampling chip 3 converts the obtained sampling resistor voltage analog value Vanalog into a digital signal Vraw through analog-to-digital conversion. Meanwhile, the sampling chip 3 has a temperature-sensitive resistor, and the sampling chip 3 converts the acquired analog value of the temperature-sensitive resistor into a digital value Rt.
The control and compensation module 2 realizes the functions of driving and communication of the sampling chip 3, configuration and driving of the CAN communication module 4, signals of an analog-digital sampling port of the control and compensation module, configuration of a timer terminal and the like. The control and compensation module 2 obtains the reference voltages Vref1, Vref2 and Vref3 of the sampling chip 3 in the control circuit from the power supply module 5 through the analog-digital sampling port at regular time. The control and compensation module 2 also obtains the chip temperature T through its own temperature sensing resistor.
The control and compensation module 2 receives the sampling resistance voltage value Vraw and the temperature sensing resistance value Rt sent by the sampling chip 3 in the current sampling process, performs compensation calculation on input parameters to obtain the current Shunt sampling resistance value Rshunt, the temperature value Tshunt and the measured current value I, and then sends the calculated values to external equipment through the CAN communication module 4. Since the control and compensation module 2 needs to calculate the final sampling current through the compensation parameters, it needs to determine accurate compensation parameters to compensate the influence of the temperature on the signal acquisition and processing links of the sampling resistor, the single chip and the sampling chip.
As shown in fig. 2, the current sampling device of the new energy vehicle high-voltage system is calibrated through the test platform 7 to determine the compensation parameter, and the signal S1 includes the reference actual current value, the actual sampling resistance temperature, and the actual shunt sampling resistance voltage of the test platform 7; the signal S2 includes a sampling resistance voltage value Vraw obtained by the sampling chip 3, a temperature sensing resistance value Rt, chip reference voltages Vref1, Vref2, Vref3 obtained by the control and compensation module 2, and a chip temperature T; signal S3 includes calculating compensation parameters a1, a2, a3... an; the signal S4 includes input parameters Vraw, Rt, T, Vref1, Vref2, Vref3 and output parameters Rshunt, Tshunt and I of the control and compensation module 2; the signal 5 comprises a measurement result sampling resistance value Rshunt, a temperature value Tschunt and a measured current value I. Specifically, a current sampling device of a high-voltage system of the new energy vehicle is connected in series on a test loop of a test platform, then a direct current source and a CAN bus test device are connected into the current sampling device of the high-voltage system of the new energy vehicle through a current sensing interface, a plurality of enough current test points are selected by calibration parameter software 8 of the test platform 7 according to the measuring range of the current sampling device of the high-voltage system of the new energy vehicle, an accurate current value is given in the test loop, enough time (generally more than 10 s) is maintained to keep the current and the temperature measured by a current sensor stable, and the calibration parameter software 8 obtains input parameters Vrad, Rt, T, Vref1, Vref2, Vref3 and output parameters Rshunt, Tshunt and I of the control and compensation module 2 in real time at the moment. And after obtaining enough current test point data, performing regression algorithm calculation on the obtained input and output parameters to obtain the calculated compensation parameters a1, a2 and a3.. And finally, the compensation parameters a1, a2 and a3. are calibrated and collected in the control and compensation module 2 of the current sampling device of the high-voltage system of the new energy vehicle to be refreshed and fixed, and during actual measurement, the control and compensation module 2 outputs Rshunt, Tshunt and I to the external equipment 9 through the interface 6.
As shown in figure 3, in the range of the testing temperature of-40-140 ℃, the error between the testing current of the current sampling device of the high-voltage system of the new energy vehicle and the reference current of the testing platform is kept within the range of +/-0.5%, and the high-precision measurement of the current of the tested circuit can be ensured in the normal use range.
Claims (5)
1. The utility model provides a new energy car high voltage system's current sampling device, its characterized in that, including sampling resistor, control and compensation module, sampling chip, power module and interface, sampling resistor connect in sampling chip by sampling chip gathers sampling resistor's voltage, control and compensation module connect sampling chip with the interface, control and compensation module receive sampling resistor's voltage and sampling chip's temperature sensing resistance, control and compensation module basis sampling resistor's voltage temperature sensing resistance adopts the compensation parameter to calculate and obtain sampling current and output, power module does control and compensation module with sampling chip supplies power.
2. The current sampling device of the new energy vehicle high-voltage system according to claim 1, wherein the control and compensation module is provided with a temperature sensing resistor, the control and compensation module obtains a self temperature signal according to the temperature sensing resistor, and the voltage of the sampling resistor, the resistance value of the temperature sensing resistor and the self temperature signal are obtained when the compensation parameter is adopted for calculation to obtain the sampling current.
3. The current sampling device of the new energy vehicle high-voltage system according to claim 2, wherein the control and compensation module obtains a reference voltage value of the sampling chip, and the voltage of the sampling resistor, the resistance value of the temperature-sensitive resistor, the reference voltage value and the self temperature signal are used for calculating a sampling current by using a compensation parameter.
4. The current sampling device of the new energy vehicle high-voltage system according to claim 3, wherein the reference voltage value is not less than two.
5. The current sampling device of the new energy vehicle high-voltage system according to claim 1, comprising a CAN communication module, wherein the CAN communication module is electrically connected with the control and compensation module, and the CAN communication module sends a signal to the outside through the interface.
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Cited By (1)
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CN114924109A (en) * | 2022-07-20 | 2022-08-19 | 深圳市英特瑞半导体科技有限公司 | Method, circuit and device for testing low-power chip current |
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