An intelligent BDU insulation detection circuit

Abstract

The present invention provides an intelligent BDU insulation detection circuit, comprising a power module, a controller, a ±15V pulse power supply module, a pulse generation module, an addition module, and an AD conversion module. The present invention injects a ±15V pulse AC signal into a power battery, detects the positive and negative voltages of a DC bus of the power battery, and calculates the insulation resistance of the power battery according to the positive and negative voltages of the DC bus. The detection process is not affected by the DC power supply, and the detection accuracy is high, the error is small, and the reliability is high.

Description

Technical Field

[0001] The present invention relates to the technical field of BDU, and in particular to an intelligent BDU insulation detection circuit. Background Art

[0002] At present, electric vehicles are becoming more and more popular. Power batteries are one of the important components of electric vehicles. Lithium-ion batteries are usually used as power batteries for electric vehicles. Power batteries need to meet the requirements of high power output. The DC voltage is generally higher than 300V, which is much higher than the human safety voltage of 36V. Therefore, the insulation between the body and the battery pack is very important. The detection of insulation resistance has always been one of the core contents in the research and development of electric vehicles. Real-time detection of the insulation resistance of the power battery is crucial to ensure the safety of the entire vehicle.

[0003] The high-voltage distribution box (BDU) of electric vehicles serves as the distribution unit of the system and has the function of detecting the insulation resistance of the power battery. The common method is to inject a low-voltage DC signal of a certain frequency between the positive and negative poles of the power battery, and obtain the insulation resistance of the system by measuring the system feedback. Since the injected DC voltage is easily affected by the system DC power supply, the detection accuracy is low. Summary of the invention

[0004] The problem solved by the present invention is that the detection method of injecting a DC voltage between the positive and negative electrodes of a power battery by a conventional BDU insulation detection circuit is affected by a system DC power supply, resulting in low detection accuracy.

[0005] To solve the above problems, the present invention proposes an intelligent BDU insulation detection circuit, comprising a power module, a controller, a ±15V pulse power supply module, a pulse generating module, an adding module, and an AD conversion module; the power module is used to power the controller, the ±15V pulse power supply module, and the AD conversion module; the output end of the ±15V pulse power supply module is respectively connected to the power supply end of the pulse generating module and the adding module, and is used to power the pulse generating module and the adding module with ±15V; the first control end of the controller is connected to the input end of the pulse generating module, and is used to control the pulse generating module to generate ±15V pulses and inject the ±15V pulses into a high-voltage power battery; the positive and negative voltages of the high-voltage power battery are respectively input into the input end of the adding module after voltage division; the output end of the adding module is connected to the input end of the AD conversion module, and the AD conversion module is communicatively connected to the controller; the controller is also used to calculate the insulation resistance of the high-voltage power battery according to the pulse acquisition signal output by the AD conversion module.

[0006] Optionally, the intelligent BDU insulation detection circuit also includes a first voltage stabilizing module and a second voltage stabilizing module. The positive output end of the ±15V pulse power supply module is connected to the positive power supply ends of the pulse generating module and the adding module respectively via the first voltage stabilizing module, and the negative output end of the ±15V pulse power supply module is connected to the negative power supply ends of the pulse generating module and the adding module respectively via the second voltage stabilizing module.

[0007] Optionally, the first voltage stabilizing module includes a TL431 chip, a transistor Q13, a resistor R150, a resistor R163, and a resistor R164. The forward output end of the ±15V pulse power supply module is connected to the collector of the transistor Q13, and the collector of the transistor Q13 is also connected to its base via the resistor R150. The emitter of the transistor Q13 is grounded via the resistor R163 and the resistor R164 in turn. The K pole of the TL431 chip is connected to the base of the transistor Q13, the A pole of the TL431 chip is grounded, and the common end of the resistor R163 and the resistor R164 is connected to the R pole of the TL431 chip.

[0008] Optionally, the first voltage stabilizing module further includes a resistor R162 and a capacitor C134, and the R pole of the TL431 chip is also connected to the K pole thereof via the capacitor C134 and the resistor R162 in sequence.

[0009] Optionally, the intelligent BDU insulation detection circuit also includes a pulse output switch, the second control end of the controller is connected to the input end of the pulse output switch, the output end of the pulse output switch is connected to the output end of the pulse generating module, and the pulse output switch is used to control the output of the pulse generating module.

[0010] Optionally, the pulse output switch includes an AQW214 chip, a transistor Q10, a resistor R291, a resistor R292, and a resistor R303; the second control end of the controller is connected to the base of the transistor Q10 via the resistor R292; the base of the transistor Q10 is also connected to its emitter via the resistor R303; the emitter of the transistor Q10 is grounded; the LED1+ pin and LED2+ pin of the AQW214 chip are both connected to the output end of the power module, the LED1- pin and LED2- pin are both connected to the collector of the transistor Q10, the 2DN pin is grounded via the resistor R291, the 1DN pin is connected to the 2DP pin, and the 1DP pin is connected to the output end of the pulse generating module.

[0011] Optionally, the intelligent BDU insulation detection circuit also includes a voltage following module, which is connected between the high-voltage power battery and the addition module. The positive and negative voltages of the high-voltage power battery are respectively input into the two in-phase input terminals of the voltage following module after voltage division, and the two inverting input terminals of the voltage following module are both connected to the input terminal of the addition module.

[0012] Optionally, the intelligent BDU insulation detection circuit also includes a reference voltage module, the output end of the power module is connected to the input end of the reference voltage module, the output end of the reference voltage module is connected to the input end of the addition module, and the reference voltage module is used to provide a reference voltage.

[0013] Optionally, the reference voltage module includes a TL4050 chip, a resistor R31, a capacitor C160, and a capacitor C64. The output end of the power supply module is connected to pin 1 of the TL4050 chip via resistor R31. Pins 2 and 3 of the TL4050 chip are both grounded. Pin 1 of the TL4050 chip is also grounded via capacitor C160. Capacitor C64 is connected in parallel with capacitor C160. Pin 1 of the TL4050 chip is also connected to the input end of the addition module.

[0014] Compared with the prior art, the intelligent BDU insulation detection circuit of the present invention has the following advantages:

[0015] (1) The intelligent BDU insulation detection circuit of the present invention injects a ±15V pulse AC signal into the power battery to detect the positive and negative voltages of the DC bus of the power battery, and calculates the insulation resistance of the power battery according to the positive and negative voltages of the DC bus. The detection process is not affected by the DC power supply, and has high detection accuracy, small error, and high reliability.

[0016] (2) In the intelligent BDU insulation detection circuit described in the present invention, the first voltage stabilizing module and the second voltage stabilizing module can precisely adjust the ±15V pulse power supply module to stably output ±15V voltage, and also have a current expansion effect, which can improve the driving ability of the ±15V power supply;

[0017] (3) The intelligent BDU insulation detection circuit described in the present invention adds a reference voltage at the input end of the adding module, which can limit the range of the input voltage of the adding module, provide a measurement reference signal for the output signal of the adding module, and ensure that the output voltage of the adding module is within the design range. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural block diagram of the intelligent BDU insulation detection circuit according to an embodiment of the present invention;

[0019] Figure 2A circuit diagram of the ±15V pulse power supply module, the first voltage stabilizing module and the second voltage stabilizing module according to an embodiment of the present invention;

[0020] Figure 3 A circuit diagram of an adding module according to an embodiment of the present invention;

[0021] Figure 4 A circuit diagram of an AD conversion module according to an embodiment of the present invention;

[0022] Figure 5 A circuit diagram of a pulse output switch according to an embodiment of the present invention;

[0023] Figure 6 A circuit diagram of a voltage follower module according to an embodiment of the present invention;

[0024] Figure 7 A circuit diagram of a reference voltage module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, it is a structural block diagram of the intelligent BDU insulation detection circuit in this embodiment, and the intelligent BDU insulation detection circuit includes a power supply module, a controller, a ±15V pulse power supply module, a pulse generation module, an addition module, and an AD conversion module; the power supply module is used to power the controller, the ±15V pulse power supply module, and the AD conversion module; the output end of the ±15V pulse power supply module is respectively connected to the power supply end of the pulse generation module and the addition module, and is used to power the pulse generation module and the addition module with ±15V; the first control end of the controller is connected to the input end of the pulse generation module, and is used to control the pulse generation module to generate ±15V pulses and inject the ±15V pulses into the high-voltage power battery; the positive and negative voltages of the high-voltage power battery are respectively input into the input end of the addition module after voltage division; the output end of the addition module is connected to the input end of the AD conversion module, and the AD conversion module is connected to the controller in communication; the controller is also used to calculate the insulation resistance of the high-voltage power battery according to the pulse acquisition signal output by the AD conversion module.

[0027] In this embodiment, the power module is a common power module, which outputs a 5V voltage. Figure 2As shown, the ±15V power supply circuit composed of the ±15V pulse power supply module CS5171EDR8 chip is preferred, the common end of the resistor R100 and the diode D46 is the positive output end of the ±15V pulse power supply module, and the pin 1 of the Schottky diode BAT54SW is the negative output end of the ±15V pulse power supply module. By setting the resistance values ​​of the resistor R100 and the resistor R148, the ±15V pulse power supply module can output a ±15V voltage. The preferred pulse generating module includes an ACPL-227 chip, a resistor R102, and a resistor R196. The first control end of the controller includes two control pins. One control pin is connected to the LED2- pin of the ACPL-227 chip via the resistor R102 and is connected to the LED1+ pin of the ACPL-227 chip via the resistor R196. The other control pin is directly connected to the LED1- pin and the LED2+ pin of the ACPL-227 chip at the same time. The two control pins output two switching signals respectively to control the ACPL-227 chip to output ±15V pulses. The ±15V pulses are injected between the DC bus and the chassis of the system. The D1 pin of the ACPL-227 chip is the positive power supply end of the pulse generating module, the S2 pin is the negative power supply end of the pulse generating module, the S1 pin is the output end of the pulse generating module, and the S1 pin is also connected to the D2 pin. Figure 3 As shown, the preferred adding module is an adder composed of an OPA180QDGKRQ1 chip, the -IN pin of the OPA180QDGKRQ1 chip is connected to its OUT pin, the positive and negative voltages of the high-voltage power battery are input to the +IN pin of the OPA180QDGKRQ1 chip after voltage division and current limiting, and the added signal is output through the OUT pin of the OPA180QDGKRQ1 chip. Figure 4 As shown, the preferred AD conversion module includes an ADS1118QDGSRQ1 chip, the ADS1118QDGSRQ1 chip is connected to the controller via SPI communication, and the signal output by the OPA180QDGKRQ1 chip is AD converted by the ADS1118QDGSRQ1 chip and then transmitted to the controller.

[0028] In this embodiment, the controller outputs two switch signals through the first control terminal to control the ACPL-227 chip to generate ±15V pulses. After the ±15V pulses are injected into the high-voltage power battery, the positive and negative voltages of the DC bus of the power battery will change accordingly. The changed terminal voltage of the power battery is processed and input into the controller for resistance calculation. By comparing it with the set threshold, the insulation of the power battery can be judged. Among them, the addition module is used to convert the two-way terminal voltage acquisition signals into a range that can be recognized by the AD conversion module.

[0029] In this way, the present embodiment can inject a ±15V pulse AC signal into the power battery to detect the positive and negative voltages of the DC bus of the power battery, and calculate the insulation resistance of the power battery based on the positive and negative voltages of the DC bus. The detection process is not affected by the DC power supply, and the detection accuracy is high, the error is small, and the reliability is high.

[0030] Optional, such as Figure 1 As shown, the intelligent BDU insulation detection circuit also includes a first voltage stabilizing module and a second voltage stabilizing module. The positive output end of the ±15V pulse power supply module is connected to the positive power supply end of the pulse generating module and the adding module respectively via the first voltage stabilizing module, and the negative output end of the ±15V pulse power supply module is connected to the negative power supply end of the pulse generating module and the adding module respectively via the second voltage stabilizing module.

[0031] Specifically, Figure 2As shown, the first voltage stabilizing module includes a TL431 chip, an NPN transistor Q13, a resistor R150, a resistor R163, and a resistor R164. The positive output end of the ±15V pulse power supply module is connected to the collector of the transistor Q13, and the collector of the transistor Q13 is also connected to its base via the resistor R150. The emitter of the transistor Q13 is grounded via the resistor R163 and the resistor R164 in sequence. The K pole of the TL431 chip is connected to the base of the transistor Q13, the A pole of the TL431 chip is grounded, and the common end of the resistor R163 and the resistor R164 is connected to the R pole of the TL431 chip. The second voltage stabilizing module includes a TL431 chip, a PNP transistor Q5, a resistor R86, a resistor R160, and a resistor R161. The negative output end of the ±15V pulse power supply module is connected to the collector of the transistor Q5, and the collector of the transistor Q5 is also connected to its base via the resistor R86. The emitter of the transistor Q5 is grounded via the resistor R160 and the resistor R161 in turn. The A pole of the TL431 chip is connected to the base of the transistor Q5, the K pole of the TL431 chip is grounded, and the common end of the resistor R160 and the resistor R161 is connected to the R pole of the TL431 chip. Here, in the ±15V pulse power supply module, the resistance values ​​of the resistor R100 and the resistor R148 can be set to 13K and 1K respectively, the resistance values ​​of the resistor R160 and the resistor R161 can be set to 4.7K and 1K respectively, and the resistance values ​​of the resistor R163 and the resistor R164 can be set to 4.7K and 1K respectively. In actual process, the ±15V power supply through the ±15V pulse power supply module is often unstable, and the output of the ±15V pulse power supply module needs to be stabilized. In this embodiment, the TL431 chip is a controllable precision voltage source, and its output voltage can be arbitrarily set to any value in the range from Vref (2.5V) to 36V with two resistors. Its output current is large, and the ±15V pulse power supply module can be precisely adjusted to stably output ±15V voltage. Among them, the transistor Q13 works in the amplification area. When the K pole of the TL431 chip provides a weak current to the base of the transistor Q13, an amplified current can be obtained at the collector of the transistor Q13. The transistor Q13 has a current expansion effect, which can be used to improve the driving ability of the ±15V power supply.

[0032] Optional, such as Figure 2 As shown, the first voltage stabilizing module also includes a resistor R162 and a capacitor C134, and the R pole of the TL431 chip is also connected to its K pole via the capacitor C134 and the resistor R162 in sequence. The resistor R162 and the capacitor C134 can be used to perform frequency compensation on the feedback loop of the TL431 chip, making the output PWM wave more stable and reducing the fluctuation of the output voltage.

[0033] Optional, such as Figure 1As shown, the intelligent BDU insulation detection circuit also includes a pulse output switch, the second control end of the controller is connected to the input end of the pulse output switch, the output end of the pulse output switch is connected to the output end of the pulse generating module, and the pulse output switch is used to control the output of the pulse generating module. Figure 5 As shown, the pulse output switch includes an AQW214 chip, a transistor Q10, a resistor R291, a resistor R292, and a resistor R303. The second control end of the controller is connected to the base of the transistor Q10 via the resistor R292, and the base of the transistor Q10 is also connected to its emitter via the resistor R303, and the emitter of the transistor Q10 is grounded; the LED1+ pin and the LED2+ pin of the AQW214 chip are both connected to the output end of the power module, the LED1- pin and the LED2- pin are both connected to the collector of the transistor Q10, the 2DN pin is grounded via the resistor R291, the 1DN pin is connected to the 2DP pin, and the 1DP pin is connected to the output end of the pulse generation module. Among them, the second control end of the controller controls the turn-off of the transistor Q10, and then controls the AQW214 chip, so that the controller and the AQW214 chip jointly control the pulse output of the pulse generation module, and the pulse output switch can ensure that the pulse output of the pulse generation module is controllable.

[0034] Optional, such as Figure 1 As shown, the intelligent BDU insulation detection circuit also includes a voltage follower module, which is connected between the high-voltage power battery and the addition module. The positive and negative voltages of the high-voltage power battery are respectively input into the two in-phase input terminals of the voltage follower module after voltage division, and the two inverting input terminals of the voltage follower module are both connected to the input terminals of the addition module. Figure 6 As shown, in this embodiment, the preferred voltage follower module is a voltage follower circuit composed of an OPA2180QDGKRQ1 chip. The positive and negative voltages of the high-voltage power battery are respectively input into the +INA pin and +INB pin of the OPA2180QDGKRQ1 chip after voltage division, and the output signals of the OUTA pin and OUTB pin of the OPA2180QDGKRQ1 chip are input into the +IN pin of the OPA180QDGKRQ1 chip after current limiting. The -INA pin of the OPA2180QDGKRQ1 chip is connected to its OUTA pin, and the -INB pin is connected to its OUTB pin. In this embodiment, the addition module is composed of an operational amplifier, and the positive and negative input terminals of the addition module need to be impedance matched, so that the voltage drop caused by the offset current of the positive and negative input terminals can be offset, and the output accuracy of the addition module can be improved.

[0035] Optional, such as Figure 1As shown, the intelligent BDU insulation detection circuit also includes a reference voltage module, the output end of the power module is connected to the input end of the reference voltage module, the output end of the reference voltage module is connected to the input end of the addition module, and the reference voltage module is used to provide a reference voltage. Specifically, as Figure 7 As shown, the reference voltage module includes a TL4050 chip, a resistor R31, a capacitor C160, and a capacitor C64. The output end of the power module is connected to the No. 1 pin of the TL4050 chip via the resistor R31, the No. 2 pin and the No. 3 pin of the TL4050 chip are both grounded, the No. 1 pin of the TL4050 chip is also grounded via the capacitor C160, the capacitor C64 is connected in parallel with the capacitor C160, and the No. 1 pin of the TL4050 chip is also connected to the input end of the addition module. In this embodiment, the reference voltage module is provided to provide a 4.1V reference voltage according to the 5V voltage output by the power module. In this embodiment, the addition module is used to sum the collected positive and negative voltages of the DC bus and convert them into a voltage range that can be recognized by the AD conversion module, but since the positive and negative voltages of the DC bus are difficult to predict, they may exceed the conversion capacity of the addition module. In this embodiment, adding a reference voltage at the input end of the addition module can limit the range of the input voltage of the addition module, provide a benchmark signal for measuring the output signal of the addition module, and ensure that the output voltage of the addition module is within the design range.

[0036] Optional, such as Figure 1 As shown, the intelligent BDU insulation detection circuit also includes a digital isolator, and the SPI port of the AD conversion module is connected to the SPI port of the controller via the digital isolator. Specifically, the digital isolator includes an ISO7341CQDWRQ1 chip, and the B1 pin, B2 pin, B3 pin, and B4 pin of the ISO7341CQDWRQ1 chip are respectively connected to the DIN pin, SCLK pin, CS pin, and DOUT pin of the ADS1118QDGSRQ1 chip in a one-to-one correspondence, and the A1 pin, A2 pin, A3 pin, and A4 pin of the ISO7341CQDWRQ1 chip are respectively connected to the MOSI pin, SCK pin, CS pin, and MISO pin of the controller in a one-to-one correspondence. The digital isolator is used to digitally isolate the communication between the AD conversion module and the controller to prevent the circuit from being damaged when communicating with each other.

[0037] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. An intelligent BDU insulation detection circuit, characterized in that: It includes a power supply module, a controller, a ±15V pulse power supply module, a pulse generation module, an addition module, and an AD conversion module; the power supply module is used to power the controller, the ±15V pulse power supply module, and the AD conversion module; the output end of the ±15V pulse power supply module is respectively connected to the power supply end of the pulse generation module and the addition module, and is used to supply ±15V to the pulse generation module and the addition module; the first control end of the controller is connected to the input end of the pulse generation module, and is used to control the pulse generation module to generate ±15V pulses and inject the ±15V pulses into the high-voltage power battery; the positive and negative voltages of the high-voltage power battery are respectively input into the input end of the addition module after voltage division; the output end of the addition module is connected to the input end of the AD conversion module, and the AD conversion module is in communication with the controller; the controller is also used to calculate the insulation resistance of the high-voltage power battery according to the pulse acquisition signal output by the AD conversion module; After the ±15V pulse is injected into the high-voltage power battery, the positive and negative voltages of the DC bus of the high-voltage power battery will change accordingly. The changed terminal voltage of the high-voltage power battery is input into the controller for resistance calculation after processing, and compared with the set threshold value to judge the insulation of the high-voltage power battery, wherein the addition module is used to sum the collected positive and negative voltages of the DC bus and convert them into a voltage range that can be recognized by the AD conversion module; It also includes a first voltage stabilizing module and a second voltage stabilizing module, wherein the positive output end of the ±15V pulse power supply module is respectively connected to the positive power supply ends of the pulse generating module and the adding module via the first voltage stabilizing module, and the negative output end of the ±15V pulse power supply module is respectively connected to the negative power supply ends of the pulse generating module and the adding module via the second voltage stabilizing module; The first voltage stabilizing module includes a TL431 chip, a transistor Q13, a resistor R150, a resistor R163, and a resistor R164. The positive output end of the ±15V pulse power supply module is connected to the collector of the transistor Q13, and the collector of the transistor Q13 is also connected to its base via the resistor R150. The emitter of the transistor Q13 is grounded via the resistor R163 and the resistor R164 in sequence. The K pole of the TL431 chip is connected to the base of the transistor Q13, the A pole of the TL431 chip is grounded, and the common end of the resistor R163 and the resistor R164 is connected to the R pole of the TL431 chip; The first voltage stabilizing module further includes a resistor R162 and a capacitor C134, and the R pole of the TL431 chip is also connected to the K pole thereof via the capacitor C134 and the resistor R162 in sequence; It also includes a pulse output switch, wherein the second control end of the controller is connected to the input end of the pulse output switch, the output end of the pulse output switch is connected to the output end of the pulse generating module, and the pulse output switch is used to control the output of the pulse generating module; The pulse output switch includes an AQW214 chip, a transistor Q10, a resistor R291, a resistor R292, and a resistor R303. The second control end of the controller is connected to the base of the transistor Q10 via the resistor R292, the base of the transistor Q10 is also connected to its emitter via the resistor R303, and the emitter of the transistor Q10 is grounded; the LED1+ pin and the LED2+ pin of the AQW214 chip are both connected to the output end of the power module, the LED1- pin and the LED2- pin are both connected to the collector of the transistor Q10, the 2DN pin is grounded via the resistor R291, the 1DN pin is connected to the 2DP pin, and the 1DP pin is connected to the output end of the pulse generating module.

2. The intelligent BDU insulation detection circuit according to claim 1 is characterized in that: It also includes a voltage follower module, which is connected between the high-voltage power battery and the addition module. The positive and negative voltages of the high-voltage power battery are respectively input into the two in-phase input terminals of the voltage follower module after voltage division, and the two inverting input terminals of the voltage follower module are both connected to the input terminal of the addition module.

3. The intelligent BDU insulation detection circuit according to claim 1 is characterized in that: It also includes a reference voltage module, the output end of the power module is connected to the input end of the reference voltage module, the output end of the reference voltage module is connected to the input end of the addition module, and the reference voltage module is used to provide a reference voltage.

4. The intelligent BDU insulation detection circuit according to claim 3 is characterized in that: The reference voltage module includes a TL4050 chip, a resistor R31, a capacitor C160, and a capacitor C64. The output end of the power supply module is connected to pin 1 of the TL4050 chip via the resistor R31. Pins 2 and 3 of the TL4050 chip are both grounded. Pin 1 of the TL4050 chip is also grounded via capacitor C160. Capacitor C64 is connected in parallel with capacitor C160. Pin 1 of the TL4050 chip is also connected to the input end of the addition module.

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