Discharge resistance testing device

Abstract

The utility model relates to a discharge resistance testing device which comprises a control unit and a detection unit. The control unit includes a microcontroller provided with a digital sampling input port, first and second analog sampling input ports, and a digital quantity output port. The detection unit comprises a voltage change rate detection circuit, a voltage division circuit, an isolator, a temperature sensor, a relay, a relay control circuit, a capacitor interface used for being connected with at least one capacitor, and a resistor interface used for being connected with a detected discharge resistor. The digital sampling input port, the first analog sampling input port and the second analog sampling input port are configured to be respectively coupled with the voltage change rate detection circuit, the voltage division circuit and the temperature sensor so as to receive signals, and the microcontroller is configured to sample the signals so as to check the discharge capability of the detected discharge resistor. The digital quantity output port is coupled with the relay control circuit, and the microcontroller sends a control signal to the relay control circuit through the digital quantity output port so as to control closing and opening of the relay.

Description

Technical Field

[0001] The utility model relates to the technical field of motor control of electric vehicles, in particular to the test technology of an active discharge resistor for driving a motor controller. Background Art

[0002] In an electric vehicle, a motor controller is a key power component for realizing the power conversion of a power battery and motor drive. A large-capacity support capacitor is integrated inside it. In case of emergencies such as collision and short circuit, the high voltage on the capacitor poses a threat to electrical appliances and personal safety. Therefore, it is usually required that a discharge circuit be provided for the DC-side capacitor of the motor controller to quickly reduce the voltage of the DC-side capacitor to a safe voltage (below 60V).

[0003] Currently, there are mainly two discharge methods: active discharge and passive discharge. According to the national standard "GB / T 18488.1-2015" for drive motor systems of electric vehicles, active discharge means that when the drive motor controller is powered off and a dedicated discharge circuit is switched in, the process of rapid discharge of the controller support capacitor.

[0004] To achieve high-voltage safety, the national standard clearly stipulates that after a vehicle collision, high-voltage power-off should be carried out immediately to avoid electric shock accidents caused by direct or indirect contact between personnel and high-voltage live parts after the collision. When there is an active discharge requirement for the drive motor controller, the discharge time of the drive motor controller support capacitor should not exceed 3 seconds.

[0005] If a collision occurs during the use of the whole vehicle, the electric drive assembly needs to execute one or more of the following protection measures according to the instructions of the vehicle controller: 1) The motor controller cuts off the load current and has no power output; 2) The electric drive assembly activates the no-load state; 3) Activate the safety state of the electric drive assembly; 4) Actively discharge the high-voltage circuit.

[0006] An active discharge circuit generally consists of a discharge resistor, a MOS tube, a switch control circuit, etc. A kind of active discharge circuit for an electric vehicle is disclosed in the Chinese utility model patent CN 206962695 U.

[0007] Therefore, a discharge resistor is necessary inside the inverter (hereinafter referred to as IVT) of an electric vehicle to complete the discharge of relevant safety strategies. The reliability and life of the discharge resistor are both very important. After calculating, designing, and selecting the discharge resistor, engineering verification (high and low temperature, life test, etc.) is required.

[0008] Currently, such engineering verification requires equipment such as high and low voltage power supplies, IVT prototypes, oscilloscopes, signal generators, and data acquisition instruments, and can only be completed after joint equipment debugging. Moreover, data recording is relatively complex, and the environment setup is time-consuming and laborious. At the initial stage of the project, there is a risk of damaging the prototype. At the same time, it can only be applied to prototypes of one platform and cannot be compatible with prototypes of various platforms (which may have different bus voltages and bus capacitances).

[0009] The present utility model aims to at least partially solve the above technical problems. Summary of the Utility Model

[0010] The purpose of the present utility model is to provide an integrated discharge resistor testing device, which has multiple functions such as protection and sampling, and can be widely used for testing different discharge resistors.

[0011] The present utility model provides a discharge resistor testing device, which includes: a control unit, the control unit includes a microcontroller, the microcontroller is provided with a digital sampling input port, a first analog sampling input port, a second analog sampling input port, and a digital output port; and a detection unit, the detection unit includes a voltage change rate detection circuit, a voltage dividing circuit, an isolator, a temperature sensor, a relay, a relay control circuit, a capacitor interface for connecting at least one capacitor, and a resistor interface for connecting the discharge resistor to be measured, wherein at least one capacitor and the discharge resistor to be measured can be respectively connected to the detection unit through the capacitor interface and the resistor interface, wherein the digital sampling input port, the first analog sampling input port, and the second analog sampling input port are configured to be respectively coupled with the voltage change rate detection circuit, the voltage dividing circuit, and the temperature sensor to receive signals, the microcontroller is configured to sample the signals to check the discharge ability of the discharge resistor to be measured, and the digital output port is coupled with the relay control circuit, and the microcontroller is configured to send a control signal to the relay control circuit through the digital output port to control the closing and opening of the relay.

[0012] Optionally, the control unit further includes a first power supply port for connecting the control unit to a low voltage power supply and an output port for outputting test data to peripheral devices, and the detection unit further includes a second power supply port for connecting the detection unit to a high voltage power supply.

[0013] Optionally, the voltage change rate detection circuit is connected to the digital sampling input port through an isolator, and the voltage dividing circuit is connected to the first analog sampling input port through an isolator.

[0014] Optionally, the relay is configured to be connected between the second power supply port and the connected capacitor, and is also connected between the second power supply port and the connected discharge resistor.

[0015] Optionally, the detection unit further includes an MOS transistor, which is configured to be connected to an access discharge resistor and controlled to conduct and turn off by a voltage change rate detection circuit.

[0016] Optionally, the voltage change rate detection circuit turns on and discharges the MOS transistor once every predetermined period, and detects the voltage change rate to confirm whether it conforms to the discharge characteristics.

[0017] Optionally, the voltage dividing circuit is also connected to the access discharge resistor to detect the voltage signal of the discharge resistor, and the microcontroller is configured to sample the voltage signal to obtain the discharge curve of the discharge resistor.

[0018] Optionally, the temperature sensor is also connected to the access discharge resistor to measure the temperature of the discharge resistor. Among them, the temperature sensor includes one or more thermistors, and the thermistors are configured to be pasted on the surface layer of the access discharge resistor.

[0019] Optionally, the discharge resistor test device further includes a temperature chamber for accommodating the detection unit, and the temperature chamber is configured to be able to simulate different ambient temperatures.

[0020] The discharge resistor test device according to the present invention has at least the following advantages:

[0021] (1) Only need to connect a high-voltage DC power supply and a low-voltage power supply that can limit current, reducing the use of related peripheral devices (such as data acquisition instruments, signal generators, oscilloscopes, etc.);

[0022] (2) It can easily perform life tests for different working conditions without the support of the entire IVT; and

[0023] (3) It can adapt to different voltages and bus capacitor platforms. Description of the Drawings

[0024] Now, the embodiments of the present invention will be described in detail with reference to the drawings.

[0025] Figure 1 Schematically shows a discharge resistor test device according to an embodiment of the present invention. Detailed Embodiments

[0026] The following will describe the discharge resistor test device according to the present invention with reference to the drawings and in combination with specific embodiments. The drawings and specific embodiments are intended to schematically illustrate and explain the technical solutions of the present invention and do not constitute a limitation to the present invention.

[0027] Figure 1A discharge resistance test device 100 is shown, which device includes a control unit 10 and a detection unit 20. The control unit 10 is on the low-voltage side, and the detection unit 20 is on the high-voltage side. Generally, the device 100 is used to test the discharge ability of a discharge resistance sample. The discharge ability includes whether the voltage can be reduced to a limit value (such as a safety voltage of 60V) within a specified time and the number of discharge times that the voltage can be reduced to the limit value within a specified time, and also includes the resistance temperature rise during discharge, etc.

[0028] As Figure 1 shown, the control unit 10 may include a microcontroller or a single-chip microcomputer (MCU) 102. The MCU 102 is provided with a digital sampling input port 104, first and second analog sampling input ports 106 and 108, and a digital quantity output port 110.

[0029] In addition, the control unit 10 may further include a first power supply port 112 for connecting the control unit to a low-voltage power supply and an output port 114 for outputting test data to other devices (such as a computer). The low-voltage power supply may be 12V. The output port 114 may be a USB port.

[0030] The detection unit 20 may include a voltage change rate (dU / dt) detection circuit 202, a voltage dividing circuit 204, an isolator 206, a temperature sensor 208, a relay 210, a relay control circuit 212, a capacitor interface for accessing at least one capacitor 214, and a resistor interface for accessing the discharge resistance 216 to be measured. One or more capacitors 214 and the discharge resistance 216 to be measured can be connected to the detection unit 20 through the capacitor interface and the resistor interface respectively.

[0031] Since an interface is reserved for the resistance to be measured in the detection unit 20, the discharge resistance to be detected can be conveniently replaced. In addition, a capacitor interface is reserved for the capacitor 214 in the detection unit 20, and the required number of capacitors can be selected according to the test requirements.

[0032] In addition, the detection unit 20 may further include a second power supply port 218 to connect the detection unit 20 to a high-voltage power supply. The high-voltage power supply may be in the range of 0 to 1000V, for example.

[0033] The relay 210 is configured to be connected between the second power supply port 218 and the connected capacitor 214, and is also connected between the second power supply port 218 and the connected discharge resistance 216. When the capacitor 214 and the discharge resistance 216 to be measured are connected to the detection unit 20, the capacitor 214 and the discharge resistance 216 to be measured are connected in parallel. In use, the relay 210 can be closed to charge a capacitor bank composed of, for example, multiple capacitors 114; after reaching a predetermined charging voltage, the relay 210 is opened, so that the capacitor 114 can discharge through the discharge resistance 216.

[0034] The MCU 102 can send a control signal to the relay control circuit 212 via the digital output port 110 to control the closing / opening of the relay 210, thereby controlling the number of discharges.

[0035] The voltage change rate detection circuit 202 on the high-voltage side is connected to the digital sampling input port 104 on the low-voltage side through the isolator 206 to input the signal into the MCU 102 after the detection is performed. After the discharge resistor 216 to be measured is connected to the detection unit 20 through the interface, the voltage change rate detection circuit 202 is also connected to the discharge resistor 216 to be measured to detect the voltage change rate.

[0036] The detection unit 20 further includes an MOS transistor 220, which is connected to the connected discharge resistor 216. The MOS transistor 220 can be controlled to conduct / turn off by the voltage change rate detection circuit 202. When the MOS transistor 220 conducts, the discharge resistor 216 can be connected to the negative pole of the high-voltage power supply to discharge, and when the MOS transistor 220 turns off, the discharge resistor 216 is disconnected from the negative pole of the high-voltage power supply to stop discharging.

[0037] During the discharge process, the voltage change rate detection circuit 202 can, for example, turn on the MOS transistor 220 and discharge once every predetermined period (such as several milliseconds) and detect the voltage change rate to confirm whether it conforms to the discharge characteristics. That is to say, if the measured voltage change rate is greater than or equal to the predetermined threshold, it can be considered that the discharge characteristics are met, that is, the discharge is successful; if the measured voltage change rate is less than the predetermined threshold, it is considered that the discharge characteristics are not met, that is, the discharge is unsuccessful. The measured voltage change rate signal is input into the MCU 102 through the digital sampling input port 104, as described above.

[0038] In addition, during the charging process of the capacitor 214, it is also possible to prevent the discharge resistor 216 to be measured from being burned out, so it can play a protective role. For example, when the MOS transistor is turned on, if the bus voltage does not drop, the value of the voltage change rate (dU / dt) will be close to 0, which means that the bus capacitor and the high-voltage DC power supply are still in a connected state. At the moment when the MOS transistor is turned on, if it is confirmed that dU / dt is too small, the voltage change rate detection circuit 202 will send a signal to prevent the MOS transistor from turning on, that is, the discharge path where the discharge resistor 216 to be measured is located is cut off, so as to protect the discharge resistor 216.

[0039] The voltage-dividing circuit 204 on the high-voltage side is connected to the first analog sampling input port 106 on the low-voltage side via the isolator 206 to input the voltage signal after voltage division into the MCU 102. After the discharge resistor 216 to be measured is connected to the detection unit 20 via the interface, the voltage-dividing circuit 204 is also connected to the discharge resistor 216 to be measured to detect the voltage of the discharge resistor 216. Specifically, the high-voltage positive terminal of the discharge resistor 216 to be measured can be connected to the high-voltage ground through a large resistor. After voltage division, the isolator 206 sends the signal to the MCU 102, and then the MCU 102 can calculate the voltage of the discharge resistor 216 in real time. The voltage-dividing circuit 204 can include a set of series-connected voltage-dividing resistors, through which the high voltage can be converted into a low voltage below 5V and transmitted to the MCU 102 through the isolator. By sampling with the MCU 102, the discharge curve can be obtained and the discharge capacity of the discharge resistor can be detected. Specifically, it is detected whether the discharge resistor can reduce the voltage to the limit value (for example, a safety voltage of 60V) within a specified time.

[0040] The temperature sensor 208 is connected to the second analog sampling input port 108. On the other hand, after the discharge resistor 216 to be measured is connected to the detection unit 20 via the interface, the temperature sensor 208 is also connected to the discharge resistor 216 to be measured to measure the temperature of the discharge resistor 216. The temperature sensor 208 can include one or more negative temperature coefficient (NTC) thermistors. The NTC thermistor can be pasted on the surface layer of the discharge resistor 216 to be measured. As the temperature of the discharge resistor 216 rises, the resistance value of the thermistor becomes larger and is converted into a voltage signal, which is transmitted to the MCU 102 via the second analog sampling input port 108, so that the temperature value of the discharge resistor 216 can be obtained.

[0041] In order to design the discharge resistor 216 that meets the requirements, its resistance power has been pre-calculated, and the magnitude of the resistance power indicates the voltage and current that the designed discharge resistor 216 can withstand. With the help of the temperature sensor 208, the actual temperature of the discharge resistor 216 during the discharge process and the cumulative heat generation degree after multiple discharges can be monitored to verify whether the power calculation result (design value) is correct.

[0042] In the present utility model, a microcontroller (single-chip microcomputer) is used for sampling on the low-voltage side, and the logic of slope, temperature and data acquisition is designed by using a program. It is connected to a computer to realize parameter setting and back-sampling and recording of relevant data through a host computer. At the same time, the microcontroller outputs a signal to control the relay; on the high-voltage side, multiple NTC thermistors can be used to measure the temperature of the sample to be measured, and different interfaces are reserved to access different bus capacitors and different resistors to be measured. The low-voltage side and the high-voltage side are connected by a cable. A voltage change rate detection circuit, an isolator, etc. are added on the high-voltage side and an isolation design is carried out, so the high-voltage side will not be connected to the low-voltage side.

[0043] Accordingly, a design of a discharge resistor test device is provided. This test device is suitable for testing discharge resistors from different suppliers in the initial stage of research and development, and integrates functions such as protection, temperature recording, and sampling within the test device. By using the test device according to the present utility model, only a high-voltage power supply and a computer (PC) are required to complete the reliability and life tests of the discharge resistor. By using the switch / interface provided inside the test device, different bus capacitors can be replaced to match the discharge resistor tests of different IVT platforms. In addition, the high-voltage part can be placed in an incubator (not shown), and this incubator can simulate different ambient temperatures for testing under different working conditions.

[0044] The numerical values disclosed in the present utility model are only examples and not limitations. Although the present utility model has been disclosed above in preferred embodiments, the present utility model is not limited thereto. Any changes and modifications made by any person skilled in the art within the spirit and scope of the present utility model shall be incorporated within the protection scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the scope defined by the claims.

Claims

1. A discharge resistor testing device, characterized in that, The discharge resistance testing device (100) includes: A control unit (10), the control unit includes a microcontroller (102), the microcontroller is provided with a digital sampling input port (104), a first analog sampling input port (106) and a second analog sampling input port (108), and a digital quantity output port (110); and A detection unit (20), the detection unit includes a voltage change rate detection circuit (202), a voltage dividing circuit (204), an isolator (206), a temperature sensor (208), a relay (210), a relay control circuit (212), a capacitor interface for accessing at least one capacitor (214), and a resistor interface for accessing the discharge resistor (216) to be measured, wherein, the at least one capacitor (214) and the discharge resistor (216) to be measured can be respectively accessed to the detection unit (20) by means of the capacitor interface and the resistor interface, wherein, the digital sampling input port (104), the first analog sampling input port (106) and the second analog sampling input port (108) are configured to be respectively coupled with the voltage change rate detection circuit (202), the voltage dividing circuit (204) and the temperature sensor (208) to receive signals, and the microcontroller (102) is configured to sample the signals to check the discharge ability of the discharge resistor (216) to be measured, and wherein, the digital quantity output port (110) is coupled with the relay control circuit (212), and the microcontroller (102) is configured to send a control signal to the relay control circuit (212) via the digital quantity output port (110) to control the closing and opening of the relay (210).

2. The discharge resistance testing device according to claim 1, characterized in that, The control unit (10) further includes a first power supply port (112) for connecting the control unit to a low-voltage power supply and an output port (114) for outputting test data to peripheral devices, and the detection unit (20) further includes a second power supply port (218) for connecting the detection unit (20) to a high-voltage power supply.

3. The discharge resistance testing device according to claim 1 or 2, characterized in that The voltage change rate detection circuit (202) is connected to the digital sampling input port (104) through the isolator (206), and the voltage dividing circuit (204) is connected to the first analog sampling input port (106) through the isolator (206).

4. The discharge resistance testing device according to claim 1 or 2, characterized in that, The relay (210) is configured to be connected between the second power supply port (218) and the accessed capacitor (214), and is also connected between the second power supply port (218) and the accessed discharge resistor (216).

5. The discharge resistance testing device according to claim 1 or 2, characterized in that, The detection unit (20) further includes a MOS transistor (220), the MOS transistor is configured to be connected to the accessed discharge resistor (216) and is controlled to be turned on and off by the voltage change rate detection circuit (202).

6. The discharge resistance testing device according to claim 5, characterized in that The voltage change rate detection circuit (202) turns on and discharges the MOS transistor (220) once every predetermined time period, and detects the voltage change rate to confirm whether it conforms to the discharge characteristics.

7. The discharge resistance testing device according to claim 1 or 2, characterized in that The voltage-dividing circuit (204) is also connected to the connected discharge resistor (216) to detect the voltage signal of the discharge resistor (216), and the microcontroller (102) is configured to sample the voltage signal to obtain the discharge curve of the discharge resistor (216).

8. The discharge resistance testing device according to claim 1 or 2, characterized in that, The temperature sensor (208) is also connected to the connected discharge resistor (216) to measure the temperature of the discharge resistor (216). Among them, the temperature sensor (208) includes one or more thermistors, and the thermistors are configured to be pasted to the surface layer of the connected discharge resistor (216).

9. The discharge resistance testing device according to claim 1 or 2, characterized in that The discharge resistor testing device (100) further includes a temperature chamber for accommodating the detection unit (20), and the temperature chamber is configured to be able to simulate different ambient temperatures.

Images