A relay electrical life test device and method based on closed-loop dynamic compensation

Abstract

The application discloses a relay electric life test device and method based on closed-loop dynamic compensation, which comprises a main control unit, an operating circuit unit, a linkage discharge unit, a cycle compensation unit and a closed-loop monitoring unit. The main control unit drives the measured relay and the linkage discharge unit to act through the microcontroller output excitation signal; the operating circuit unit simulates the real load environment; the linkage discharge unit suppresses the breaking inrush current through the RC absorption branch and the synchronous control switch; the cycle compensation unit adjusts the electric holding time of the excitation signal in real time through the dynamic compensation algorithm according to the operating circuit electric parameters and the historical opening and closing delay data collected by the closed-loop monitoring unit, forms the closed-loop compensation logic, and offsets the influence of the inherent delay of the relay. The application solves the problems of the existing test, such as the deviation of the actual electric holding time from the preset value caused by the inherent delay of the relay in the test, low test precision, etc., and guarantees the accuracy and consistency of the test.

Description

Technical Field

[0001] This invention relates to a relay testing platform, and more particularly to a relay electrical life testing device and method based on closed-loop dynamic compensation. Background Technology

[0002] As a key component in power systems and industrial control, the electrical life of relays directly affects the reliability and safety of the entire equipment, thus requiring precise life testing. Relay electrical life testing necessitates simulating the actual connection and disconnection conditions under specialized testing platforms. However, relays inherently possess a closing and disconnecting delay, which varies with usage and environmental conditions. Existing testing platforms lack dynamic compensation mechanisms for this delay, relying solely on the theoretical electrical hold time of the control pulse. This leads to actual hold times deviating from standard requirements; for example, a preset hold time of 50ms may exceed 80ms in actual testing. This deviation compromises test accuracy, fails to accurately reflect the relay's electrical life performance, and reduces the reliability and reference value of the test results. Summary of the Invention

[0003] Objectives of the invention: The first objective of this invention is to provide a relay electrical life test platform with dynamic compensation for opening and closing delays and high test accuracy; the second objective of this invention is to provide a test method based on the aforementioned test platform.

[0004] Technical Solution: The relay electrical life testing device based on closed-loop dynamic compensation of the present invention includes a main control unit, an operation circuit unit, a closed-loop monitoring unit, and a cyclic compensation unit; the main control unit includes a host computer and a microcontroller communicatively connected to the host computer; the operation circuit unit includes a DC power supply, the relay under test, and an RL load branch connected in series; the signal acquisition terminal of the closed-loop monitoring unit is connected to the operation circuit unit and is used to acquire the operation circuit electrical parameters and the opening and closing status signals of the relay under test; the signal input terminal of the cyclic compensation unit is connected to the closed-loop monitoring unit, and the output terminal is connected to the microcontroller.

[0005] The closed-loop monitoring unit sends the collected data to the cyclic compensation unit; the cyclic compensation unit dynamically calculates the time compensation value based on the closing and opening delay data in historical tests and sends it to the main control unit; the main control unit adjusts the holding time of the excitation signal of the relay under test according to the time compensation value.

[0006] Preferably, the testing device further includes a linkage discharge unit; the linkage discharge unit includes an RC absorption branch and a synchronous control switch; the RC absorption branch and the synchronous control switch are connected in series and then connected in parallel across the inductor of the RL load branch; the control terminal of the synchronous control switch is connected to the microcontroller; the microcontroller is configured to output two control signals to drive the relay under test and the synchronous control switch respectively, and to make the operating state of the synchronous control switch opposite to the operating state of the relay under test.

[0007] Preferably, the microcontroller adopts a 32-bit microprocessor based on the ARM architecture, and the 32-bit microprocessor is configured with multiple general-purpose timers for pulse generation, timeout monitoring and communication reception timeout determination.

[0008] Preferably, the resistance value of the RC absorption branch is matched with the load resistance of the RL load branch.

[0009] Preferably, the communication connection uses serial communication and is configured with a CRC16 check mechanism.

[0010] Preferably, the operating circuit electrical parameters collected by the closed-loop monitoring unit include the inductor current flowing through the RL load branch, the capacitor voltage of the RC absorption branch, and the load resistor voltage of the RL load branch.

[0011] The relay electrical life testing method based on closed-loop dynamic compensation described in this invention, applied to the device described in this invention, includes the following steps:

[0012] (1) Configure parameters and complete communication adaptation through the host computer;

[0013] (2) The microcontroller outputs an excitation signal to the relay under test, drives the relay under test to close, and synchronously controls the synchronous control switch to open, so that the operation circuit enters a zero-state response;

[0014] (3) The closed-loop monitoring unit collects the electrical parameters of the operating circuit and the opening and closing status signals of the relay under test in real time, and extracts the closing delay data;

[0015] (4) The cyclic compensation unit calculates the closing time compensation value through a dynamic compensation algorithm and sends the time compensation value to the main control unit to adjust the holding time of the excitation signal in the next operation cycle;

[0016] (5) When the adjusted holding time is reached, the microcontroller controls the relay under test to disconnect and synchronously controls the synchronous control switch to close. The energy stored in the inductor in the RL load branch is released through the RC absorption branch, so that the discharge circuit enters the zero input state. The closed-loop monitoring unit collects the electrical parameters of the linkage discharge circuit and the opening and closing status signals of the relay under test in real time and extracts the opening delay data.

[0017] (6) The cyclic compensation unit calculates the opening time compensation value through a dynamic compensation algorithm and sends the time compensation value to the main control unit to adjust the holding time of the excitation signal in the next operation cycle;

[0018] (7) Repeat steps (2) to (6) to complete the preset number of tests and record the data.

[0019] Preferably, the rising and falling edge slopes of the excitation signal are optimized by an external driver board.

[0020] Preferably, the dynamic compensation algorithm described in steps (4) and (6) is as follows:

[0021] (1) Calculate the minimum deviation value, wherein the minimum deviation value is the minimum of the previous deviation absolute value, the historical average deviation absolute value and the fixed time threshold; wherein the previous deviation absolute value is the absolute value of the difference between the actual excitation time of the previous cycle and the preset excitation time, and the historical average deviation absolute value is the absolute value of the difference between the average excitation time of the previous multiple cycles and the preset excitation time.

[0022] (2) Determine the excitation time for the next cycle based on the source of the minimum deviation value:

[0023] If the minimum deviation value is equal to the absolute value of the previous deviation or the absolute value of the historical average deviation, then the excitation time of the next cycle is equal to the preset excitation time minus half of the minimum deviation value.

[0024] If the minimum deviation value is equal to the fixed time threshold, then the excitation time of the next cycle is equal to the preset excitation time.

[0025] Preferably, the process of releasing inductor energy by the RC absorption branch in step (5) is a non-oscillating discharge.

[0026] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) It can dynamically adjust the electrical holding time of the control signal, forming a closed-loop compensation logic to offset the influence of the inherent delay of the relay; (2) It realizes the dynamic adjustment of parameters during the test process, avoids parameter drift, and ensures the consistency of multiple cycle tests; (3) The test conditions are in line with the real application scenario, improving the reliability of the test data; (4) The accuracy of instruction interaction and data transmission is high, making it easy for users to intuitively grasp the test process; (5) It effectively suppresses the inductance surge current when the relay is disconnected, avoiding arc erosion of the contacts. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the present invention;

[0028] Figure 2 This is a parameter table of the preferred microcontroller of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0030] Example 1: Device Structure

[0031] The relay electrical life testing device based on closed-loop dynamic compensation disclosed in this invention includes a main control unit, an operation circuit unit, a linkage discharge unit, a closed-loop monitoring unit, and a cyclic compensation unit.

[0032] I. Main Control Unit

[0033] The main control unit includes a host computer and a microcontroller. The host computer provides a human-machine interface for configuring test parameters, displaying test status in real time, and storing all test process data. The microcontroller receives and parses instructions and parameters from the host computer, establishes a bidirectional data interaction channel with the host computer via serial communication, outputs millisecond-level control pulses to drive the tested relay and its associated discharge unit, and collects and processes feedback signals. The serial communication preferably uses a CRC16 checksum mechanism, with big-endian byte order. The communication protocol includes a function code set and a data field. The function code set at least covers test start, pause, stop, test count configuration, and circuit breaker compensation parameter configuration instructions.

[0034] Preferably, the microcontroller uses a 32-bit STM32F103ZET6 microprocessor. This microprocessor is an ARM-based 32-bit microprocessor with 512KB of flash memory, and features USB, CAN, eight general-purpose timers, and three ADC acquisition channels. Specific parameters are detailed below. Figure 2As shown. The general-purpose timers are used for pulse generation, timeout monitoring, and serial port reception timeout determination, respectively, and are configured as a pulse generation timer, a circuit breaker opening / closing timeout monitoring timer, and a serial port reception timeout determination timer; the ADC acquisition channel is used for electrical parameter conversion of the closed-loop monitoring unit.

[0035] The timer for monitoring the opening and closing timeout is used to monitor the response time of the relay under test. When the response time exceeds a preset counting threshold, a preset error code is output and uploaded to the host computer. For example, if the monitored response time exceeds the preset counting threshold, the relay may have problems such as coil failure, contact sticking, or abnormal drive. The timer for monitoring the opening and closing timeout will immediately output a preset error code and upload it to the host computer via a serial communication link.

[0036] II. Operation Circuit Unit

[0037] The operating circuit unit includes a DC power supply, a relay under test (DUT), and an RL load branch. These three components are connected in series to form a complete current path. The input actuation coil circuit of the DUT is connected to a control signal output terminal of the microcontroller to receive its excitation signal. The open contacts of the DUT are used to control the on / off state of the operating circuit. The DC power supply provides a stable voltage output, and its voltage and power parameters must match the rated operating voltage and load requirements of the DUT to ensure that the circuit current and voltage remain stable within a preset range. The RL load branch consists of a power resistor and an inductor connected in series to form a first-order RL circuit. The resistance and inductance values ​​must be adapted according to the rated operating current of the DUT and the load type to simulate a real inductive load.

[0038] III. Linked Discharge Unit

[0039] The linkage discharge unit is used to safely release the energy stored in the inductor L in the RL load branch when the relay disconnects, preventing high-voltage arcing that could damage the relay contacts. This unit includes an RC absorption branch and a synchronous control switch. The RC absorption branch consists of a resistor and a capacitor connected in series. This series branch, after being connected in series with the synchronous control switch, is then connected in parallel across the inductor L in the RL load branch, providing a non-oscillating release path for the inductor's stored energy. The resistor dissipates the energy released by the inductor, preventing voltage spikes caused by concentrated energy; the capacitor buffers the energy release rate, preventing arcing caused by sudden current changes. The control terminal of the synchronous control switch is connected to another control signal output terminal of the microcontroller. The resistance value of the RC absorption branch is matched to the load resistance of the RL load branch, and the capacitor capacitance meets the critical damping discharge characteristics of the RLC circuit, ensuring a non-oscillating discharge process.

[0040] The synchronous control switch is linked to the relay under test, and their operating states are opposite. When the relay under test is energized and the operating circuit is open, the synchronous control switch is open, and the RC absorption branch does not intervene in the circuit, avoiding interference from the capacitor charging current to the zero-state response of the RL circuit. When the relay under test is about to disconnect, the synchronous control switch closes in advance, and the RC absorption branch is pre-connected, providing a smooth release path for the inductor's energy storage and preventing arcing and contact erosion caused by sudden changes in inductor current at the moment of relay disconnection. At the same time, the difference between the action response time of the synchronous control switch and the tripping response time of the relay under test needs to be controlled within a preset range to maintain the activation and deactivation sequence of the RC absorption branch. This prevents the switch from operating too early, which would cause capacitor charging interference when the operating circuit is open, and prevents inrush current surges caused by operating too late, which would prevent the inductor's energy storage from being released in time.

[0041] IV. Cyclic Compensation Unit

[0042] The cyclic compensation unit receives the closing and opening status signals of the relay under test, stores the closing and opening delay data, and calculates the average closing and opening times of all preceding relays. It then adjusts the electrical holding time of the main control unit's excitation signal using a dynamic compensation algorithm, forming a closed-loop compensation logic. This unit receives the closing and opening status signals of the relay under test and the magnitude of the circuit current through a signal interface, capturing and confirming the moments of contact closure and opening. This avoids sampling distortion caused by delay deviations between the drive signal and the actual action, providing accurate raw data for compensation calculations. Considering that the internal resistance of the relay coil and the contact resistance of the contacts may change slightly with the number of tests, causing fluctuations in closing and opening delays, the cyclic compensation unit's built-in storage module records the closing and opening delay data collected in the previous test cycle, the average closing and opening times of all preceding relays, and the magnitude of the circuit current. This historical data storage provides a basis for dynamic compensation. Based on the stored data, the cyclic compensation unit adjusts the electrical holding time of the main control unit's output pulse using a dynamic compensation algorithm. The dynamic compensation algorithm is as follows:

[0043] 1. Relay status confirmation. Among them, The current real-time main circuit current is represented by S; the current open / close signal position of the detected relay is represented by S.

[0044] 11. The relay is considered closed when both of the following conditions are met simultaneously:

[0045] (1) ;

[0046] (2) The relay status signal S is "closed".

[0047] 12. The relay status is confirmed as open when both of the following conditions are met simultaneously:

[0048] (1) ;

[0049] (2) The relay status signal S is “division”.

[0050] 2. Dynamic compensation calculation. First, determine the minimum deviation. :

[0051]

[0052] Then, based on the source of the minimum deviation, the compensated setpoint is calculated in the following three cases:

[0053] Case 1: If = The compensated value is then set to ;

[0054] Scenario 2: If = The compensated value is then set to ;

[0055] Scenario 3: If =0.1ms, then the compensated setpoint is .

[0056] Among them, when calculating the closing delay compensation, The set closing excitation time; This refers to the time of the previous closing excitation. This is the average closing excitation time of the preceding circuit. When calculating the opening delay compensation, The set opening excitation time; This refers to the time of the previous tripping excitation. This is the average opening excitation time of the preceding circuit breaker.

[0057] V. Closed-loop monitoring unit

[0058] The closed-loop monitoring unit is responsible for collecting the electrical parameters of the operating circuit and the opening / closing status signals of the relay under test, and feeding them back to the main control unit and the cyclic compensation unit to achieve dynamic adjustment of the testing process. Specifically, the signals collected by this unit include two types: first, the electrical parameters of the operating circuit, including the inductor current flowing through the RL load branch, the capacitor voltage across the RC absorption branch, and the voltage across the load resistor; second, the opening / closing status signals of the relay under test.

[0059] The microcontroller is configured to output two control signals: the first control signal drives the input coil of the relay under test; the second control signal drives the synchronous control switch of the linkage discharge unit. The microcontroller's program logic ensures that the two signals operate in opposite states: when the relay under test is energized, the synchronous control switch is de-energized; when the relay under test is de-energized, the synchronous control switch is de-energized. Preferably, during the de-energizing process, the microcontroller's control timing is designed as follows: first, a command is issued to close the synchronous control switch, connecting the RC absorption branch to the circuit; then, a command is issued to de-energize the relay under test. This ensures that the RC absorption branch is pre-energized at the instant the relay contacts open, providing a smooth release path for the inductor's stored energy and preventing arcing and contact erosion caused by sudden changes in inductor current at the moment of relay de-energizing.

[0060] Example 2: Test Method

[0061] This embodiment provides a relay electrical life testing method based on closed-loop dynamic compensation, applied to the testing device described in Embodiment 1 above. The method includes the following steps:

[0062] Step 1: Parameter Configuration and Communication Initialization

[0063] Users configure test parameters (including but not limited to the number of operation cycles, preset power-on time, and interval time), RL load branch parameters of the operation loop unit, and DC power supply output voltage via a host computer, thus completing the communication protocol adaptation between the microcontroller and the host computer. After configuration, the host computer sends the parameters and start command to the microcontroller via serial port.

[0064] Step 2: Relay activation and circuit completion

[0065] After receiving the instruction, the microcontroller parses the parameters and initializes the working state of each unit. Its first control terminal outputs an excitation signal that meets the action threshold to the input coil of the relay under test, driving the relay to close. Synchronously with the closing action of the relay under test, the second control terminal of the microcontroller outputs a disconnection command to the synchronous control switch of the linkage discharge unit to prevent the capacitor of the RC absorption branch from charging when the operation circuit is on, and to prevent the charging current from superimposing on the circuit start current, which would cause distortion of the current rise time constant or peak overshoot. The current rises exponentially from 0. After the operation circuit enters the zero-state response stage, each component is in the initial uncharged state. Preferably, to solve the control delay problem caused by the high frequency of opening and closing of the relay under test during the test and the degraded opening and closing performance, an intermediate relay is set between the main circuit and the discharge circuit of the test circuit. At the same time, the rising and falling edge slopes of the excitation signal can be optimized by an external driver board. The external driver board is connected to the primary drive circuit of the relay under test through the intermediate relay to provide a faster driving capability.

[0066] Step 3: Real-time monitoring and extraction of closing and opening delay signals

[0067] During the circuit conduction period and throughout the entire operation, the closed-loop monitoring unit operates continuously. On one hand, it collects electrical parameters of the operating circuit, including circuit current, load resistor voltage, load inductor voltage, and inductor current decay rate, to verify whether the circuit's zero-state response meets standard requirements and to determine whether current rise and steady-state operation are normal. On the other hand, it monitors the opening and closing status signals of the relay under test. By connecting sensors to the non-energized terminals of the main contacts, it captures key timing nodes such as contact closing and opening times, and calculates the opening delay data. After data acquisition, the closed-loop monitoring unit performs preliminary data processing and uploads the extracted opening and closing delay data to the cyclic compensation unit via a communication link, while simultaneously synchronizing it to the microcontroller.

[0068] Step 4: Dynamic Time Compensation Calculation

[0069] The cyclic compensation unit receives and stores the tripping delay data measured in the previous operation cycle, provided by the closed-loop monitoring unit. Subsequently, its internal dynamic compensation algorithm begins operation. The dynamic compensation algorithm is as follows:

[0070] 1. Relay status confirmation. Among them, The current real-time main circuit current is represented by S; the current open / close signal position of the detected relay is represented by S.

[0071] 11. The relay is considered closed when both of the following conditions are met simultaneously:

[0072] (1) ;

[0073] (2) The relay status signal S is "closed".

[0074] 12. The relay status is confirmed as open when both of the following conditions are met simultaneously:

[0075] (1) ;

[0076] (2) The relay status signal S is “division”.

[0077] 2. Dynamic compensation calculation. First, determine the minimum deviation. :

[0078]

[0079] Then, based on the source of the minimum deviation, the compensated setpoint is calculated in the following three cases:

[0080] Case 1: If = The compensated value is then set to ;

[0081] Scenario 2: If = The compensated value is then set to ;

[0082] Scenario 3: If =0.1ms, then the compensated setpoint is .

[0083] Among them, when calculating the closing delay compensation, The set closing excitation time; This refers to the time of the previous closing excitation. This is the average closing excitation time of the preceding circuit. When calculating the opening delay compensation, The set opening excitation time; This refers to the time of the previous tripping excitation. This is the average opening excitation time of the preceding circuit breaker.

[0084] Step 5: Relay disconnection and inductor energy release

[0085] When the conduction time of the operating circuit reaches the new holding time adjusted in step 4, the microcontroller outputs a signal from its second control terminal to drive the synchronous control switch of the linkage discharge unit to close. Subsequently, the first control terminal of the microcontroller stops outputting the excitation signal, causing the coil of the relay under test to de-energize and drive its main contacts to open. Since the synchronous control switch has been closed in advance, the RC absorption branch is connected in parallel across the inductor L before the relay opens. Therefore, when the relay contacts open, the magnetic energy stored in the inductor L is released through the circuit formed by the RC absorption branch. By reasonably designing the parameters of the resistor and capacitor in the RC absorption branch, this discharge process is controlled as a non-oscillating discharge. The energy is smoothly consumed by the resistor, and the capacitor acts as a buffer, thereby avoiding overvoltage and arcing at the relay contacts due to sudden current changes.

[0086] Step 6: Execute repeatedly and record data.

[0087] After completing one full cycle of "engage-hold-disengage," the device enters a preset interval. After the interval, steps 2 through 6 are repeated for the next cycle. In each cycle, step 4 dynamically compensates for the previous measured delay or the average delay of the preceding sequence. Throughout the process, the host computer receives, displays, and stores all test data in real time, including the current cycle count, opening / closing status, opening / closing time for each cycle, holding time, inductor current decay rate, compensation adjustment value, and operating circuit electrical parameters. It also records test progress, equipment status, and abnormal alarm information. When a parameter deviation exceeds a preset threshold, the host computer issues a pause command to prevent the accumulation of erroneous data. The test automatically stops after the preset total number of cycles is completed, and a complete test report is generated.

Claims

1. A relay electrical life testing device based on closed-loop dynamic compensation, characterized in that, The system includes a main control unit, an operation loop unit, a closed-loop monitoring unit, and a cyclic compensation unit. The main control unit includes a host computer and a microcontroller communicatively connected to the host computer. The operation loop unit includes a DC power supply, a relay under test, and an RL load branch connected in series. The signal acquisition terminal of the closed-loop monitoring unit is connected to the operation loop unit and is used to acquire the electrical parameters of the operation loop and the opening and closing status signals of the relay under test. The signal input terminal of the cyclic compensation unit is connected to the closed-loop monitoring unit, and the output terminal is connected to the microcontroller. The closed-loop monitoring unit sends the collected data to the cyclic compensation unit; the cyclic compensation unit dynamically calculates the time compensation value based on the closing and opening delay data in historical tests and sends it to the main control unit; the main control unit adjusts the holding time of the excitation signal of the relay under test according to the time compensation value.

2. The testing apparatus according to claim 1, characterized in that, It also includes a linkage discharge unit; the linkage discharge unit includes an RC absorption branch and a synchronous control switch; the RC absorption branch and the synchronous control switch are connected in series and then connected in parallel across the inductor of the RL load branch; the control terminal of the synchronous control switch is connected to the microcontroller; the microcontroller is configured to output two control signals to drive the relay under test and the synchronous control switch respectively, and to make the operating state of the synchronous control switch opposite to the operating state of the relay under test.

3. The testing apparatus according to claim 1, characterized in that, The microcontroller uses a 32-bit microprocessor based on the ARM architecture, and the 32-bit microprocessor is configured with multiple general-purpose timers for pulse generation, timeout monitoring, and communication reception timeout determination.

4. The testing apparatus according to claim 1, characterized in that, The resistance value of the RC absorption branch is matched with the load resistance of the RL load branch.

5. The testing apparatus according to claim 1, characterized in that, The communication connection uses serial communication and is configured with a CRC16 check mechanism.

6. The testing apparatus according to claim 1, characterized in that, The operating circuit electrical parameters collected by the closed-loop monitoring unit include the inductor current flowing through the RL load branch, the capacitor voltage of the RC absorption branch, and the load resistor voltage of the RL load branch.

7. A relay electrical life testing method based on closed-loop dynamic compensation, applied to the device as described in any one of claims 1-6, characterized in that, The method includes the following steps: (1) Configure parameters and complete communication adaptation through the host computer; (2) The microcontroller outputs an excitation signal to the relay under test, drives the relay under test to close, and synchronously controls the synchronous control switch to open, so that the operation circuit enters a zero-state response; (3) The closed-loop monitoring unit collects the electrical parameters of the operating circuit and the opening and closing status signals of the relay under test in real time, and extracts the closing delay data; (4) The cyclic compensation unit calculates the closing time compensation value through a dynamic compensation algorithm and sends the time compensation value to the main control unit to adjust the holding time of the excitation signal in the next operation cycle; (5) When the adjusted holding time is reached, the microcontroller controls the relay under test to disconnect and synchronously controls the synchronous control switch to close. The energy stored in the inductor in the RL load branch is released through the RC absorption branch, so that the discharge circuit enters the zero input state. The closed-loop monitoring unit collects the electrical parameters of the linkage discharge circuit and the opening and closing status signals of the relay under test in real time and extracts the opening delay data. (6) The cyclic compensation unit calculates the opening time compensation value through a dynamic compensation algorithm and sends the time compensation value to the main control unit to adjust the holding time of the excitation signal in the next operation cycle; (7) Repeat steps (2) to (6) to complete the preset number of tests and record the data.

8. The test method according to claim 7, characterized in that, The rising and falling edge slopes of the excitation signal are optimized by an external driver board.

9. The test method according to claim 7, characterized in that, The dynamic compensation algorithm described in steps (4) and (6) is as follows: (1) Calculate the minimum deviation value, wherein the minimum deviation value is the minimum of the previous deviation absolute value, the historical average deviation absolute value and the fixed time threshold; wherein the previous deviation absolute value is the absolute value of the difference between the actual excitation time of the previous cycle and the preset excitation time, and the historical average deviation absolute value is the absolute value of the difference between the average excitation time of the previous multiple cycles and the preset excitation time. (2) Determine the excitation time for the next cycle based on the source of the minimum deviation value: If the minimum deviation value is equal to the absolute value of the previous deviation or the absolute value of the historical average deviation, then the excitation time of the next cycle is equal to the preset excitation time minus half of the minimum deviation value. If the minimum deviation value is equal to the fixed time threshold, then the excitation time of the next cycle is equal to the preset excitation time.

10. The test method according to claim 8, characterized in that, The process of releasing inductor energy in the RC absorption branch in step (5) is a non-oscillating discharge.

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