Relay testing device for electric passenger cars under load conditions

Abstract

The utility model provides a kind of electric train relay testing device based on the state of carrying load, comprising: multiple contact test board card, coil test and control board card and industrial control host computer;Each contact test board card is used to test the contact of a certain measured relay, and upload the test result of corresponding contact;Coil test and control board card are connected with the coil of measured relay, for testing the coil of a certain measured relay, and uploading the test result of corresponding coil;The contact test board card includes constant-current source circuit, carrying load and static measurement power supply switching circuit, contact large resistance measurement circuit, contact card hysteresis measurement circuit, contact voltage acquisition circuit, first 485 communication circuit and contact MCU;Coil test and control board card includes coil MCU, second 485 communication circuit, coil power supply, coil static resistance measurement circuit, coil voltage acquisition circuit and coil energizing current acquisition circuit.

Description

Technical Field

[0001] This utility model relates to the field of relays, and in particular to a test device for electric bus relays under load conditions. Background Technology

[0002] Relays are crucial components in the control system of electric multiple units (EMUs). The causes of relay failures are complex, including high temperatures, instantaneous current spikes, arcing, contact oxidation, and mechanical malfunctions. EMU relays often experience intermittent faults, and the symptoms usually disappear by the time the fault is detected, making troubleshooting difficult.

[0003] The failure rate of electric trains has been increasing year by year due to relay problems. However, most of the testing devices for control relays of electric trains in the rail transit industry currently available in the domestic market are custom-developed products without unified standards. This results in existing testing methods and equipment having problems such as being unable to simulate the actual working conditions of relays, having limited measurement functions, and having discrete data, making it impossible to conduct in-depth analysis of intermittent relay failures.

[0004] For example, Guangzhou Metro primarily uses multimeters and its self-developed relay testing equipment when testing relays, while Hangzhou Metro mainly uses a custom-developed relay testing platform. However, these measurement methods used by both Guangzhou and Hangzhou Metro are for measuring relays in a static state, failing to accurately measure various parameters of the relays under load. This makes it impossible to plot accurate curves, thus limiting their effectiveness in locating intermittent relay faults and hindering accurate and comprehensive assessments of the relays' condition in subsequent evaluations. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a test device for electric bus relays under load conditions.

[0006] This utility model proposes a test device for electric bus relays under load conditions, including: multiple contact test boards, coil test and control boards, and industrial control host; Each contact test board is connected to a specific contact of the relay under test, and is used to test a specific contact of the relay under test. It also communicates with the industrial control host to upload the test results of the corresponding contact. The coil testing and control board is connected to the coil of the relay under test, and is used to test the coil of a certain relay under test. It also communicates with the industrial control host to upload the test results of the corresponding coil. The contact test board includes a constant current source circuit, a power switching circuit for load and static measurement, a contact high resistance measurement circuit, a contact sticking measurement circuit, a contact voltage acquisition circuit, a first 485 communication circuit, and a contact MCU. The voltage acquisition circuit at both ends of the contact is used to acquire the voltage at both ends of the contact of the relay under test; The constant current source circuit is used to provide a set constant current to the contact test board; The load and static measurement power supply switching circuit is connected to the test relay contacts and the constant current source circuit. It is used to switch the test relay contacts to a 3.3V constant current source circuit when performing static resistance measurement and a 110V constant current source circuit when performing load resistance measurement. The contact high resistance measurement circuit is a resistor voltage divider circuit, which is connected to the contact of the relay under test and is used to measure the contact resistance of high resistance values. The contact sticking measurement circuit is connected to the contacts of the relay under test and is used to measure the sticking of the contacts. The contact MCU is connected to the voltage acquisition circuit at both ends of the contact, the power switching circuit for load and static measurement, and the constant current source circuit to calculate the contact resistance based on the acquired contact voltage and the constant current provided by the connected constant current source circuit, thereby obtaining the contact static resistance and the contact load resistance. The contact MCU is connected to the contact high resistance measurement circuit to obtain the contact static resistance value of the high resistance value by means of resistor voltage division. The contact MCU is connected to the contact sticking measurement circuit to perform contact sticking measurement and obtain the sticking measurement result; The contact MCU is connected to the first 485 communication circuit to send the obtained measurement values ​​to the industrial control host. The coil testing and control board includes a coil MCU, a second 485 communication circuit, a coil power supply, a coil static resistance measurement circuit, a coil voltage acquisition circuit, and a coil current acquisition circuit. The coil power supply is an external power source used to power the coil; The coil static resistance measurement circuit is used to measure the static resistance of the tested relay coil before it is powered off. The voltage acquisition circuit at both ends of the coil is used to acquire the voltage at both ends of the coil after the coil of the relay under test is powered. The coil current acquisition circuit is used to acquire the coil current after the tested relay coil is powered on. The coil MCU circuit controls the power supply connected to the coil to control the on / off state of the tested relay coil; it is connected to the coil static resistance measurement circuit to obtain the static resistance of the tested relay coil before power is supplied; and it is connected to the voltage acquisition circuit across the coil and the coil current acquisition circuit to calculate the coil resistance based on the acquired coil voltage and current. The coil MCU circuit is connected to the second 485 communication circuit to send the collected static resistance of the test relay coil before power supply, the voltage across the coil after power supply, the current flowing through the coil after power supply, and the calculated coil resistance value to the industrial control host.

[0007] Based on the above, the contact test board also includes a contact deoxidation power supply, a deoxidation switch MOS power drive circuit, a deoxidation switch MOS control circuit, and an electronic load circuit. The contact deoxidation power supply is used to supply power for contact deoxidation; The deoxidation switch MOS power drive circuit is used for deoxidation power input, and outputs a square wave of 0.1KHZ-20KHZ through the MOS power circuit to form a DC pulsating current impact on the contacts. The deoxidation switch MOS control circuit is used to control the on / off state of the deoxidation switch MOS; The electronic load circuit is used to absorb the current from the deoxidation power supply after it passes through the contacts; The contact MCU is connected to the contact deoxidation power supply control to control the on / off power supply of the contact deoxidation power supply; it is also connected to the deoxidation switch MOS power drive circuit, the deoxidation switch MOS control circuit, and the electronic load circuit to complete the deoxidation of the contacts.

[0008] Based on the above, the deoxidation switch MOS power drive circuit adopts the MOS transistor isolation drive chip UCC23513BDWYR.

[0009] Based on the above, the voltage acquisition circuit at both ends of the contact includes a design structure using an instrumentation amplifier circuit, and a three-channel voltage acquisition circuit of the instrumentation amplifier circuit is designed using an operational amplifier.

[0010] Based on the above, the contact high resistance measurement circuit includes a four-position onboard multi-stage resistor voltage divider circuit and four analog switches. The four-position onboard multi-stage resistor voltage divider circuit is connected to both ends of the relay contact under test through a relay. The four-position onboard multi-stage resistor voltage divider circuit and the four analog switches are respectively connected to the contact MCU to realize the measurement of the contact static resistance of the relay contact under test.

[0011] Based on the above, the coil static resistance measurement circuit includes a four-position onboard multi-stage resistance voltage divider circuit and four analog switches. The four-position onboard multi-stage resistance voltage divider circuit is connected to both ends of the relay coil under test through a relay. The four-position onboard multi-stage resistance voltage divider circuit and the four analog switches are respectively connected to the coil MCU to realize the measurement of the static resistance of the relay coil under test before power supply.

[0012] Based on the above, the voltage acquisition circuit at both ends of the coil uses a voltage sensor and is connected to the coil MCU via 485 isolated communication; the coil energized current acquisition circuit uses a current sensor and is connected to the coil MCU via 485 isolated communication.

[0013] Based on the above, the electric bus relay testing device under load also includes a voltage regulator circuit; the voltage regulator circuit includes: A first low-ripple linear regulated power supply with one input of AC220V and an output voltage of DC110V; A second low-ripple linear regulated power supply with one input of AC220V and an output voltage of DC3.3V; A third low-ripple linear regulated power supply with one input of AC220V and an output voltage of DC5V. A third low-ripple linear regulated power supply with one input of DC5V and an output voltage of DC3.3V.

[0014] This utility model has substantial features and progress compared to the prior art, specifically: This invention enables the measurement of various parameters of a relay under static and load conditions by setting up multiple contact test boards and coil test and control boards. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the principle of this utility model.

[0016] Figure 2 This is the circuit diagram of a first low-ripple linear regulated power supply with an input of AC220V and an output voltage of DC110V.

[0017] Figure 3 This is the circuit diagram of a second low-ripple linear regulated power supply with an input of AC220V and an output voltage of DC3.3V.

[0018] Figure 4 This is the circuit diagram of a third low-ripple linear regulated power supply with an input of AC220V and an output voltage of DC5V.

[0019] Figure 5 This is the circuit diagram of a fourth low-ripple linear regulated power supply with an input of DC5V and an output voltage of DC3.3V.

[0020] Figure 6 This is the circuit diagram for measuring the resistance of the relay contacts.

[0021] Figure 7 This is the circuit schematic of the coil testing and control board.

[0022] Figure 8This is the schematic diagram of the contact deoxidation control circuit. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0024] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion.

[0025] like Figure 1 As shown, this embodiment proposes a test device for electric bus relays under load conditions, comprising multiple contact test boards, coil test and control boards, and an industrial control host. Each contact test board is connected to a specific contact of the relay under test, and is used to test a specific contact of the relay under test. It also communicates with the industrial control host to upload the test results of the corresponding contact. The coil testing and control board is connected to the coil of the relay under test, and is used to test the coil of a certain relay under test. It also communicates with the industrial control host to upload the test results of the corresponding coil. The contact test board includes a constant current source circuit, a power switching circuit for load and static measurement, a contact high resistance measurement circuit, a contact sticking measurement circuit, a contact voltage acquisition circuit, a first 485 communication circuit, and a contact MCU. The voltage acquisition circuit at both ends of the contact is used to acquire the voltage at both ends of the contact of the relay under test; The constant current source circuit is used to provide a set constant current to the contact test board; The load and static measurement power supply switching circuit is connected to the test relay contacts and the constant current source circuit. It is used to switch the test relay contacts to a 3.3V constant current source circuit when performing static resistance measurement and a 110V constant current source circuit when performing load resistance measurement. The contact high resistance measurement circuit is a resistor voltage divider circuit, which is connected to the contact of the relay under test and is used to measure the contact resistance of high resistance values. The contact sticking measurement circuit is connected to the contacts of the relay under test and is used to measure the sticking of the contacts. The contact MCU is connected to the voltage acquisition circuit at both ends of the contact, the power switching circuit for load and static measurement, and the constant current source circuit to calculate the contact resistance based on the acquired contact voltage and the constant current provided by the connected constant current source circuit, thereby obtaining the contact static resistance and the contact load resistance. The contact MCU is connected to the contact high resistance measurement circuit to obtain the contact static resistance value of the high resistance value by means of resistor voltage division. The contact MCU is connected to the contact sticking measurement circuit to perform contact sticking measurement and obtain the sticking measurement result; The contact MCU is connected to the first 485 communication circuit to send the obtained measurement values ​​to the industrial control host. The coil testing and control board includes a coil MCU, a second 485 communication circuit, a coil power supply, a coil static resistance measurement circuit, a coil voltage acquisition circuit, and a coil current acquisition circuit. The coil power supply is an external power source used to power the coil; The coil static resistance measurement circuit is used to measure the static resistance of the tested relay coil before it is powered off. The voltage acquisition circuit at both ends of the coil is used to acquire the voltage at both ends of the coil after the coil of the relay under test is powered. The coil current acquisition circuit is used to acquire the coil current after the tested relay coil is powered on. The coil MCU circuit controls the power supply connected to the coil to control the on / off state of the tested relay coil; it is connected to the coil static resistance measurement circuit to obtain the static resistance of the tested relay coil before power is supplied; and it is connected to the voltage acquisition circuit across the coil and the coil current acquisition circuit to calculate the coil resistance based on the acquired coil voltage and current. The coil MCU circuit is connected to the second 485 communication circuit to send the collected static resistance of the test relay coil before power supply, the voltage across the coil after power supply, the current flowing through the coil after power supply, and the calculated coil resistance value to the industrial control host.

[0026] In some exemplary embodiments, the contact test board further includes a contact deoxidation power supply, a deoxidation switch MOS power drive circuit, a deoxidation switch MOS control circuit, and an electronic load circuit. The contact deoxidation power supply is used to supply power for contact deoxidation; The deoxidation switch MOS power drive circuit is used for deoxidation power input, and outputs a square wave of 0.1KHZ-20KHZ through the MOS power circuit to form a DC pulsating current impact on the contacts. The deoxidation switch MOS control circuit is used to control the on / off state of the deoxidation switch MOS; The electronic load circuit is used to absorb the current from the deoxidation power supply after it passes through the contacts; The contact MCU is connected to the contact deoxidation power supply control to control the on / off power supply of the contact deoxidation power supply; it is also connected to the deoxidation switch MOS power drive circuit, the deoxidation switch MOS control circuit, and the electronic load circuit to complete the deoxidation of the contacts.

[0027] Since the resistance of relay contacts is typically in the milliohm range, the designed circuit must be able to measure resistance in the milliohm range with high accuracy. To realize the functionality of the contact test board, the power supply section of the contact test board includes a voltage regulator circuit, such as... Figures 2-5 As shown, it includes: A low-ripple linear regulated power supply with one input of AC220V and an output voltage of DC110V; used to power load measurements under simulated operating conditions. A second low-ripple linear regulated power supply with one input of AC220V and an output voltage of DC3.3V; used to power static measurements; A third low-ripple linear regulated power supply with one input AC220V and an output voltage DC5V; used to power the relays in the device. A fourth low-ripple linear regulated power supply with one input of DC5V and an output voltage of DC3.3V; used to power the control circuit in the device.

[0028] In this embodiment, specifically, Figure 6 This is a circuit diagram for measuring the resistance of relay contacts. It includes a constant current source circuit, a power supply switching circuit for load and static measurement, a circuit for measuring high contact resistance, a circuit for measuring contact sticking, and a circuit for acquiring the voltage across the contacts.

[0029] Figure 6 In this circuit, transistor Q7, a 1R sampling resistor, and operational amplifier U53.2 constitute the main structure of the constant current source circuit. When current flows through the 1R sampling resistor, the voltage across the resistor increases, and the voltage at the inverting input of operational amplifier U53.2 also increases. However, due to the virtual short and virtual open principles of operational amplifiers, operational amplifier U53.2 will adjust the conduction level of transistor Q7 through negative feedback, thereby keeping the current flowing through the 1R sampling resistor constant. This ensures that the voltage at the inverting input of operational amplifier U53.2 is equal to the voltage at the non-inverting input (DAC). Therefore, the voltage value of DAC determines the constant current value of the circuit. The constant current of the constant current source circuit can be set by the contact MCU outputting the DAC voltage value. The contacts of the relay under test are connected to a constant current source circuit via relay U54. The constant current source circuit is powered by two relays, K1 and K2, from the load and static measurement power switching circuit. K1 and K2 determine the power supply switching of the constant current source circuit. When K1 is closed, the 110V load measurement power supply is connected to the constant current source circuit; when K2 is closed, the 3.3V static measurement power supply is connected. The contact MCU sets the current value of the constant current source circuit, resulting in a constant current flowing through the contacts of the relay under test. Because the contacts have resistance, a corresponding voltage is generated across them. Since the current is constant, the resistance of the contacts can be accurately calculated using R=U / I by precisely measuring the voltage across the contacts.

[0030] The voltage acquisition circuit across the contact terminals is connected to the two ends of the relay under test via relay U55. This circuit is a high-precision instrument amplification circuit with three different voltage gain levels. It simultaneously acquires the voltage across the contact terminals, thereby expanding the acquisition range while maintaining accuracy. Additionally, the DAC output of the contact MCU has seven different constant current levels. Thus, through the combination of constant current and voltage gain levels, there are 21 customizable levels for high-precision acquisition of the contact voltage, meeting the requirements of a 0-200Ω contact resistance measurement range and a 0.5mΩ measurement accuracy.

[0031] When the contact resistance is too high, exceeding 200Ω, the contact MCU controls relays U54 and U55 to isolate the contact under test from the voltage acquisition circuit and constant current source circuit at both ends of the contact, thereby connecting the contact under test to the contact high resistance measurement circuit. The contact high resistance measurement circuit uses a multi-stage resistor voltage divider circuit with four positions on the board combined with the control of the analog switch to measure the resistance of the contact under test from 10Ω to 200KΩ. Its measurement principle is the same as that of the relay coil static resistance measurement circuit. When the contact resistance measurement range is at its maximum, the contact MCU sets the voltage acquisition IO of ADC1 to a high or low level acquisition IO. The high or low level of this IO can be used to quickly determine the contact's closed or open state, thereby realizing the contact sticking measurement and obtaining the sticking measurement result.

[0032] In this embodiment, specifically, Figure 7 This is the circuit schematic of a coil testing and control board. It includes the coil static resistance measurement circuit, the coil voltage acquisition circuit, and the coil current acquisition circuit.

[0033] Figure 7In this circuit, the coil is powered by an independent external power supply. The power supply voltage is input through the input interface and is controlled by relay U1 to connect or disconnect the coil of the relay under test from this power supply, thus energizing or de-energizing the coil. Relay U1 is controlled by the high and low levels of IO1 of the coil MCU. When relay U1 is disconnected and the coil is de-energized, the coil MCU controls relay U2 to be energized through IO2, connecting the static coil of the relay under test to the coil static resistance measurement circuit. At this time, the coil of the relay under test is connected to resistors R14, R9, R6, and R5, and can be connected to GND through the selection of the analog switch to form an onboard multi-stage resistance voltage divider acquisition circuit. The resistance values ​​of resistors R14, R9, R6, and R5 are 1K ohms, 100K ohms, 10K ohms, and 220 ohms, respectively. The coil MCU acquires the voltages V1 and V2 across resistors R14, R9, R6, and R5 respectively via ADC1 and ADC2. It then determines the precise potential difference between the upper end of the relay coil under test and the lower end of the voltage divider resistor using 3.3V-V2, and determines the voltage across the coil under test using 3.3V-V1. By utilizing the principle of voltage division of multi-stage resistors on the series board, the coil resistance can be calculated. The coil resistance measurement range is wide (0 ohms to 1M ohms).

[0034] Figure 7 To ensure measurement accuracy, four resistors and an analog switch are used for range switching, guaranteeing measurement accuracy across the entire measurement range. The voltage and current of the coil under test are acquired by an isolated acquisition module and transmitted to the coil MCU via RS-485 isolated communication. The coil MCU receives the voltage and current data and calculates the resistance value of the relay coil.

[0035] In this embodiment, specifically, Figure 8 This is a schematic diagram of the contact deoxidation control circuit. The circuit includes the control and drive circuitry for the deoxidation MOSFET, as well as the main circuit structure for deoxidation.

[0036] Figure 8 In this circuit, the contact deoxidation power supply is an external power module. This power supply establishes communication with the deoxidation control circuit microcontroller (contact MCU) via 485 communication. The contact MCU can adjust the voltage of the contact deoxidation power supply via 485 communication. The contact deoxidation electronic load circuit is also an external electronic load module, which also establishes communication with the contact MCU via 485 communication. The contact MCU can adjust the constant current of the electronic load via 485 communication to determine the current passing through the deoxidation contacts. Figure 8The deoxidation power supply is connected to one end of the contact to be deoxidized via two MOSFETs, U8 and U10. The other end of the contact is connected to the input of the electronic load, thus forming a deoxidation circuit. The on / off state of the two MOSFETs, U8 and U10, determines the on / off state of the deoxidation voltage. The two MOSFETs are used in parallel to meet the high power requirements. The two MOSFETs are driven by U9 (a MOSFET isolation driver chip). The PWM output from the contact MCU drives U9 through a transistor Q6, which in turn drives the MOSFETs, thus achieving perfect isolation control. In this way, the current passing through the contact to be deoxidized can be pulsated DC by the MOSFETs for deoxidation.

[0037] The system provided in this application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A test device for electric bus relays under load conditions, characterized in that, include: Multiple contact test boards, coil test and control boards, and industrial control host; Each contact test board is connected to a specific contact of the relay under test, and is used to test a specific contact of the relay under test. It also communicates with the industrial control host to upload the test results of the corresponding contact. The coil testing and control board is connected to the coil of the relay under test, and is used to test the coil of a certain relay under test. It also communicates with the industrial control host to upload the test results of the corresponding coil. The contact test board includes a constant current source circuit, a power switching circuit for load and static measurement, a contact high resistance measurement circuit, a contact sticking measurement circuit, a contact voltage acquisition circuit, a first 485 communication circuit, and a contact MCU. The voltage acquisition circuit at both ends of the contact is used to acquire the voltage at both ends of the contact of the relay under test; The constant current source circuit is used to provide a set constant current to the contact test board; The load and static measurement power supply switching circuit is connected to the test relay contacts and the constant current source circuit. It is used to switch the test relay contacts to a 3.3V constant current source circuit when performing static resistance measurement and a 110V constant current source circuit when performing load resistance measurement. The contact high resistance measurement circuit is a resistor voltage divider circuit, which is connected to the contact of the relay under test and is used to measure the contact resistance of high resistance values. The contact sticking measurement circuit is connected to the contacts of the relay under test and is used to measure the sticking of the contacts. The contact MCU is connected to the voltage acquisition circuit at both ends of the contact, the power switching circuit for load and static measurement, and the constant current source circuit to calculate the contact resistance based on the acquired contact voltage and the constant current provided by the connected constant current source circuit, thereby obtaining the contact static resistance and the contact load resistance. The contact MCU is connected to the contact high resistance measurement circuit to obtain the contact static resistance value of the high resistance value by means of resistor voltage division. The contact MCU is connected to the contact sticking measurement circuit to perform contact sticking measurement and obtain the sticking measurement result; The contact MCU is connected to the first 485 communication circuit to send the obtained measurement values ​​to the industrial control host. The coil testing and control board includes a coil MCU, a second 485 communication circuit, a coil power supply, a coil static resistance measurement circuit, a coil voltage acquisition circuit, and a coil current acquisition circuit. The coil power supply is an external power source used to power the coil; The coil static resistance measurement circuit is used to measure the static resistance of the tested relay coil before it is powered off. The voltage acquisition circuit at both ends of the coil is used to acquire the voltage at both ends of the coil after the coil of the relay under test is powered. The coil current acquisition circuit is used to acquire the coil current after the tested relay coil is powered on. The coil MCU circuit controls the power supply connected to the coil to control the on / off state of the tested relay coil; it is connected to the coil static resistance measurement circuit to obtain the static resistance of the tested relay coil before power is supplied; and it is connected to the voltage acquisition circuit across the coil and the coil current acquisition circuit to calculate the coil resistance based on the acquired coil voltage and current. The coil MCU circuit is connected to the second 485 communication circuit to send the collected static resistance of the test relay coil before power supply, the voltage across the coil after power supply, the current flowing through the coil after power supply, and the calculated coil resistance value to the industrial control host.

2. The electric bus relay testing device based on the loaded state as described in claim 1, characterized in that, The contact test board also includes a contact deoxidation power supply, a deoxidation switch MOS power drive circuit, a deoxidation switch MOS control circuit, and an electronic load circuit. The contact deoxidation power supply is used to supply power for contact deoxidation; The deoxidation switch MOS power drive circuit is used for deoxidation power input, and outputs a square wave of 0.1KHZ-20KHZ through the MOS power circuit to form a DC pulsating current impact on the contacts. The deoxidation switch MOS control circuit is used to control the on / off state of the deoxidation switch MOS; The electronic load circuit is used to absorb the current from the deoxidation power supply after it passes through the contacts; The contact MCU is connected to the contact deoxidation power supply control to control the on / off power supply of the contact deoxidation power supply; it is also connected to the deoxidation switch MOS power drive circuit, the deoxidation switch MOS control circuit, and the electronic load circuit to complete the deoxidation of the contacts.

3. The electric bus relay testing device based on the loaded state according to claim 2, characterized in that, The deoxidation switch MOS power drive circuit uses the MOS transistor isolation drive chip UCC23513BDWYR.

4. The electric bus relay testing device based on a load-bearing state according to any one of claims 1-3, characterized in that, The voltage acquisition circuit at both ends of the contact includes a design structure using an instrumentation amplifier circuit, and a three-channel voltage acquisition circuit of the instrumentation amplifier circuit is designed using an operational amplifier.

5. The electric bus relay testing device based on a load-bearing state according to any one of claims 1-3, characterized in that, The contact high resistance measurement circuit includes a four-position onboard multi-stage resistor voltage divider circuit and four analog switches. The four-position onboard multi-stage resistor voltage divider circuit is connected to both ends of the relay contact under test through a relay. The four-position onboard multi-stage resistor voltage divider circuit and the four analog switches are respectively connected to the contact MCU to realize the measurement of the contact static resistance of the relay contact under test.

6. The electric bus relay testing device based on a load-bearing state according to any one of claims 1-3, characterized in that, The coil static resistance measurement circuit includes a four-position onboard multi-stage resistance voltage divider circuit and four analog switches. The four-position onboard multi-stage resistance voltage divider circuit is connected to both ends of the relay coil under test through a relay. The four-position onboard multi-stage resistance voltage divider circuit and the four analog switches are respectively connected to the coil MCU to realize the measurement of the static resistance of the relay coil under test before power supply.

7. The electric bus relay testing device based on a load-bearing state according to any one of claims 1-3, characterized in that, The voltage acquisition circuit at both ends of the coil uses a voltage sensor and is connected to the coil MCU via 485 isolated communication; the coil energized current acquisition circuit uses a current sensor and is connected to the coil MCU via 485 isolated communication.

8. The electric bus relay testing device based on a load-bearing state according to any one of claims 1-3, characterized in that, The electric bus relay test device based on the load condition also includes a voltage regulator circuit; The regulated power supply circuit includes: A first low-ripple linear regulated power supply with one input of AC220V and an output voltage of DC110V; A second low-ripple linear regulated power supply with one input of AC220V and an output voltage of DC3.3V; A third low-ripple linear regulated power supply with one input of AC220V and an output voltage of DC5V. A third low-ripple linear regulated power supply with one input of DC5V and an output voltage of DC3.3V.

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