Elevator star connection detection system, elevator and elevator star connection detection method

Abstract

The present invention discloses an elevator star connection detection system, an elevator and an elevator star connection detection method, including: a control module, a traction machine, a star connection contactor, a test power supply module, a three-phase transformer and a current and voltage detection module. The output end of the control module is connected to the winding of the traction machine for supplying power to the traction machine. The output end of the control module is connected to the control end of the star connection contactor for controlling the closing or opening of the star connection contactor. The output end of the control module is connected to the control end of the test power supply module for controlling the test power supply module to output three-phase alternating current. The output end of the test power supply module is connected to the primary side winding of the three-phase transformer. The secondary side winding of the three-phase transformer is connected to one end of the star connection contactor. The other end of the star connection contactor is connected to the winding of the traction machine. The current and voltage detection module is used to detect the voltage and current of the winding of the traction machine. The output end of the current and voltage detection module is connected to the input end of the control module to realize the detection of the reliability of the star connection contactor.

Description

Technical Field

[0001] The present invention relates to the technical field of elevator star - short - circuit detection, and particularly to an elevator star - short - circuit detection system, an elevator, and an elevator star - short - circuit detection method. Background Art

[0002] An elevator generally stops by the brake of the traction machine. When the brake fails, dangerous situations such as elevator overspeed, over - running at the top, or crashing to the bottom may occur. Currently, the method to deal with the failure of the brake is to use a star - short - circuit contactor to short - circuit the windings of the traction machine, so that the traction machine is in a power - generating state, and the reverse electromagnetic induction torque generated by the windings is used to limit the acceleration of the elevator, thereby reducing the risks of elevator overspeed, over - running at the top, or crashing to the bottom. In order to ensure the reliability of the star - short - circuit contactor, it is necessary to detect the elevator star - short - circuit circuit. The existing method for detecting the elevator star - short - circuit circuit is to let the elevator coast and measure the elevator speed to determine whether the star - short - circuit contactor is effective, but the detection requires testing at specific floors, and the method is relatively cumbersome. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides an elevator star - short - circuit detection system, an elevator, and an elevator star - short - circuit detection method, which can solve the problem of the cumbersome existing elevator star - short - circuit detection method.

[0004] The elevator star - short - circuit detection system according to the first - aspect embodiment of the present invention includes: a control module; a traction machine, the output end of the control module is connected to the windings of the traction machine for supplying power to the traction machine; a star - short - circuit contactor, the output end of the control module is connected to the control end of the star - short - circuit contactor for controlling the closing or opening of the star - short - circuit contactor; a test power supply module, the output end of the control module is connected to the control end of the test power supply module for controlling the test power supply module to output three - phase alternating current; a three - phase transformer, the output end of the test power supply module is connected to the primary - side winding of the three - phase transformer, the secondary - side winding of the three - phase transformer is connected to one end of the star - short - circuit contactor, the other end of the star - short - circuit contactor is connected to the windings of the traction machine, a current - voltage detection module, the current - voltage detection module is used to detect the voltage and current of the windings of the traction machine, the output end of the current - voltage detection module is connected to the input end of the control module, the control module controls the closing or opening of the star - short - circuit contactor, the current - voltage detection module detects the voltage and current of the windings of the traction machine, and the control module determines whether the voltage and current of the windings of the traction machine are preset values. If both the voltage and current of the windings of the traction machine are preset values, it is confirmed that the star - short - circuit contactor is normal.

[0005] The elevator star - short - circuit detection system according to the first - aspect embodiment of the present invention has at least the following beneficial effects:

[0006] By stopping the power supply to the traction machine, controlling the closing of the star connection contactor, testing the three-phase AC power input from the power supply module to the three-phase transformer, and obtaining the first current, the first voltage, the second current, and the second voltage. The first current is the current of the primary side winding of the three-phase transformer, the first voltage is the voltage of the primary side winding of the three-phase transformer, the second current is the current of the winding of the traction machine, and the second voltage is the voltage of the winding of the traction machine. The turns ratio of the three-phase transformer is N:1. If the second current is N times the first current and the second voltage is 1 / N of the first voltage, it is determined that the closing state of the star connection contactor is normal; otherwise, it is determined that the closing state of the star connection contactor is abnormal. Control the star connection contactor to disconnect, and obtain the second current and the second voltage. If the second current and the second voltage are 0, it is determined that the disconnection state of the star connection contactor is normal; otherwise, it is determined that the disconnection state of the star connection contactor is abnormal. When it is determined that both the closing state and the disconnection state of the star connection contactor are normal, it is confirmed that the function of the star connection contactor is normal. During the detection process, the winding of the traction machine is short-circuited by closing the star connection contactor. Due to the existence of the three-phase transformer, it will not cause a short circuit of the test power supply module, realizing the detection of the reliability of the star connection contactor, without the need for the elevator to coast, and without the need to test on specific floors of the elevator. The method is simple and efficient.

[0007] According to some embodiments of the present invention, the test power supply module is a frequency modulation and voltage regulation module. The input end of the frequency modulation and voltage regulation module is used to connect to an external power supply, the output end of the frequency modulation and voltage regulation module is connected to the primary side winding of the three-phase transformer, and the output end of the control module is connected to the control end of the frequency modulation and voltage regulation module.

[0008] According to some embodiments of the present invention, the control module includes a first control module and a second control module. The output end of the first control module is connected to the winding of the traction machine to supply power to the traction machine. The output end of the second control module is connected to the control end of the test power supply module. The output end of the current and voltage detection module is connected to the input end of the second control module. The first control module is connected to the second control module.

[0009] According to some embodiments of the present invention, it further includes a communication module. The second control module is communicatively connected to the first control module through the communication module, and the second control module is communicatively connected to the current and voltage detection module through the communication module.

[0010] According to some embodiments of the present invention, the star connection contactor is a normally closed star connection contactor.

[0011] According to some embodiments of the present invention, the star connection contactor is a normally open star connection contactor.

[0012] According to an embodiment of the second aspect of the present invention, an elevator includes the above-mentioned elevator star connection detection system.

[0013] The elevator according to the second aspect embodiment of the present invention has at least the following beneficial effects:

[0014] By stopping the power supply to the traction machine, controlling the closing of the star contactor, testing the power supply module to input three-phase alternating current to the three-phase transformer, and obtaining the first current, the first voltage, the second current, and the second voltage. The first current is the current of the primary side winding of the three-phase transformer, the first voltage is the voltage of the primary side winding of the three-phase transformer, the second current is the current of the winding of the traction machine, and the second voltage is the voltage of the winding of the traction machine. The turns ratio of the three-phase transformer is N:1. If the second current is N times the first current and the second voltage is 1 / N of the first voltage, it is determined that the closing state of the star contactor is normal; otherwise, it is determined that the closing state of the star contactor is abnormal. Control the star contactor to disconnect, and obtain the second current and the second voltage. If the second current and the second voltage are 0, it is determined that the disconnection state of the star contactor is normal; otherwise, it is determined that the disconnection state of the star contactor is abnormal. When it is determined that both the closing state and the disconnection state of the star contactor are normal, it is confirmed that the function of the star contactor is normal. During the detection process, the winding of the traction machine is short-circuited by the closing of the star contactor. Due to the existence of the three-phase transformer, it will not cause a short circuit of the test power supply module, realizing the detection of the reliability of the star contactor, without the need for the elevator to slip, and without the need to test on specific floors of the elevator. The method is simple and efficient.

[0015] The elevator star contactor detection method according to the third aspect embodiment of the present invention includes: stopping the power supply to the traction machine and controlling the closing of the star contactor; testing the power supply module to input three-phase alternating current to the three-phase transformer, and obtaining the first current, the first voltage, the second current, and the second voltage. The first current is the current of the primary side winding of the three-phase transformer, the first voltage is the voltage of the primary side winding of the three-phase transformer, the second current is the current of the winding of the traction machine, and the second voltage is the voltage of the winding of the traction machine. The turns ratio of the three-phase transformer is N:1; if the second current is N times the first current and the second voltage is 1 / N of the first voltage, it is determined that the closing state of the star contactor is normal; otherwise, it is determined that the closing state of the star contactor is abnormal; control the star contactor to disconnect, and obtain the second current and the second voltage. If the second current and the second voltage are 0, it is determined that the disconnection state of the star contactor is normal; otherwise, it is determined that the disconnection state of the star contactor is abnormal; when it is determined that both the closing state and the disconnection state of the star contactor are normal, it is confirmed that the function of the star contactor is normal.

[0016] The elevator star contactor detection method according to the third aspect embodiment of the present invention has at least the following beneficial effects:

[0017] By stopping the power supply to the traction machine, controlling the closing of the star connection contactor, testing the three-phase AC power input by the power supply module to the three-phase transformer, and obtaining the first current, the first voltage, the second current, and the second voltage. The first current is the current of the primary side winding of the three-phase transformer, the first voltage is the voltage of the primary side winding of the three-phase transformer, the second current is the current of the winding of the traction machine, and the second voltage is the voltage of the winding of the traction machine. The turns ratio of the three-phase transformer is N:1. If the second current is N times the first current and the second voltage is 1 / N of the first voltage, it is determined that the closing state of the star connection contactor is normal; otherwise, it is determined that the closing state of the star connection contactor is abnormal. Control the star connection contactor to disconnect, and obtain the second current and the second voltage. If the second current and the second voltage are 0, it is determined that the disconnection state of the star connection contactor is normal; otherwise, it is determined that the disconnection state of the star connection contactor is abnormal. When it is determined that both the closing state and the disconnection state of the star connection contactor are normal, it is confirmed that the function of the star connection contactor is normal. During the detection process, the windings of the traction machine are short-circuited by closing the star connection contactor. Due to the presence of the three-phase transformer, it will not cause a short circuit of the test power supply module, realizing the detection of the reliability of the star connection contactor. There is no need for the elevator to slip, and there is no need to test on specific floors of the elevator. The method is simple and efficient.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the drawings and embodiments, where:

[0020] Figure 1 is the circuit diagram of the elevator star connection detection system of the present invention;

[0021] Figure 2 is the flowchart of the elevator star connection detection method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0023] In the description of the present invention, it should be understood that the orientation or positional relationship involved, such as up, down, etc., indicates the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0024] In the description of the present invention, "a plurality of" refers to more than two. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0025] In the description of the present invention, unless otherwise clearly defined, terms such as "arrangement", "installation", and "connection" should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0026] As Figure 1 shown, the elevator star connection detection system according to the first aspect embodiment of the present invention includes: a control module, a traction machine M1, a star connection contactor KM1, a test power supply module, a three-phase transformer T1, and a current and voltage detection module S1. The output end of the control module is connected to the winding of the traction machine M1 for supplying power to the traction machine M1. The output end of the control module is connected to the control end of the star connection contactor KM1 for controlling the closing or opening of the star connection contactor KM1. The output end of the control module is connected to the control end of the test power supply module for controlling the test power supply module to output three-phase alternating current. The output end of the test power supply module is connected to the primary side winding of the three-phase transformer T1. The secondary side winding of the three-phase transformer T1 is connected to one end of the star connection contactor KM1. The other end of the star connection contactor KM1 is connected to the winding of the traction machine M1. The current and voltage detection module S1 is used to detect the voltage and current of the winding of the traction machine M1. The output end of the current and voltage detection module S1 is connected to the input end of the control module. The control module controls the closing or opening of the star connection contactor KM1. The current and voltage detection module S1 detects the voltage and current of the winding of the traction machine M1. The control module determines whether the voltage and current of the winding of the traction machine M1 are preset values. If both the voltage and current of the winding of the traction machine M1 are preset values, it is confirmed that the star connection contactor KM1 is normal. The star connection contactor KM1 can adopt a normally closed star connection contactor KM1, which can still keep the contacts closed when the elevator is powered off, realizing the star connection function of the traction machine M1, which is safe and reliable. The star connection contactor KM1 can also adopt a normally open star connection contactor KM1, which can keep the contacts open when the elevator makes an emergency stop during operation, avoiding the impact of high voltage and current of the winding of the traction machine M1, and then closing when the elevator speed drops to the allowable range. The current and voltage detection module S1 is a current and voltage sensor.

[0027] By stopping the power supply to the traction machine M1, controlling the closing of the star connection contactor, testing the three-phase AC power input from the power supply module to the three-phase transformer T1, and obtaining the first current, the first voltage, the second current, and the second voltage. The first current is the current of the primary side winding of the three-phase transformer T1, the first voltage is the voltage of the primary side winding of the three-phase transformer T1, the second current is the current of the winding of the traction machine M1, and the second voltage is the voltage of the winding of the traction machine M1. The turns ratio of the three-phase transformer T1 is N:1. If the second current is N times the first current and the second voltage is 1 / N of the first voltage, it is determined that the closing state of the star connection contactor KM1 is normal; otherwise, it is determined that the closing state of the star connection contactor KM1 is abnormal. Control the star connection contactor KM1 to disconnect, and detect the second current and the second voltage through the current and voltage detection module S1. If the second current and the second voltage are 0, it is determined that the disconnection state of the star connection contactor KM1 is normal; otherwise, it is determined that the disconnection state of the star connection contactor KM1 is abnormal. When it is determined that both the closing state and the disconnection state of the star connection contactor KM1 are normal, it is confirmed that the function of the star connection contactor KM1 is normal. During the detection process, the winding of the traction machine is short-circuited by the closing of the star connection contactor KM1. Due to the presence of the three-phase transformer T1, it will not cause a short circuit of the test power supply module. At the same time, the three-phase transformer T1 makes a specific ratio relationship exist between the first voltage and the second voltage, and the first current and the second current, making the detection result judgment more accurate, realizing the detection of the reliability of the star connection contactor KM1, without the need for the elevator to coast, and without the need to test on specific floors of the elevator. The method is simple and efficient.

[0028] Both ends of the control coil of the star connection contactor KM1 are connected in parallel to a delay circuit. The delay circuit includes an energy storage element. When the elevator is powered on, the delay circuit is not connected in parallel with the star connection contactor KM1. At this time, the energy storage element in the delay circuit is charging. When the elevator loses power, the delay circuit is connected in parallel across both ends of the coil of the star connection contactor KM1. At this time, the energy storage element in the delay circuit discharges, so that the star connection contactor KM1 closes with a delay, avoiding the impact of high voltage and current of the winding of the traction machine M1 on the star connection contactor KM1.

[0029] As Figure 1 As shown, the test power supply module is a frequency modulation and voltage regulation module U2. The input end of the frequency modulation and voltage regulation module U2 is used to connect to an external power supply. The output end of the frequency modulation and voltage regulation module U2 is connected to the primary side winding of the three-phase transformer T1. The output end of the control module is connected to the control end of the frequency modulation and voltage regulation module U2. The frequency modulation and voltage regulation module U2 converts the external power supply into low-voltage three-phase AC power and supplies it to the primary side winding of the three-phase transformer T1.

[0030] As Figure 1As shown in the figure, the control module includes a first control module U1 and a second control module U3. The output terminal of the first control module U1 is connected to the winding of the traction machine M1. The output terminal of the second control module U3 is connected to the control terminal of the test power supply module. The output terminal of the current and voltage detection module S1 is connected to the input terminal of the second control module U3. The first control module U1 is connected to the second control module U3. The first control module U1 controls the energization or de-energization of the traction machine M1 to make the traction machine M1 work or stop. The second control module U3 controls the test power supply module to supply power to the primary side winding of the three-phase transformer T1. The first control module U1 is the original elevator controller in the elevator, which controls the operation of the elevator.

[0031] It further includes a communication module. The second control module U3 is communicatively connected to the first control module U1 through the communication module. The second control module U3 is communicatively connected to the current and voltage detection module S1 through the communication module. The first control module U1 and the second control module U3 perform data transmission through the communication module. The second control module U3 receives the data detected by the current and voltage detection module S1 through the communication module. The communication module can adopt a wired communication module, such as an RS485 communication module, to achieve stable data transmission. The communication module can also adopt a wireless communication module, such as a 4G module, which is not restricted by the installation environment and can achieve long-distance transmission.

[0032] The elevator according to the second aspect embodiment of the present invention includes the above-mentioned elevator star connection detection system.

[0033] By stopping the power supply to the traction machine M1, controlling the closing of the star connection contactor, testing the power supply module to input three-phase alternating current to the three-phase transformer T1, obtaining the first current, the first voltage, the second current and the second voltage, the first current is the current of the primary side winding of the three-phase transformer T1, the first voltage is the voltage of the primary side winding of the three-phase transformer T1, the second current is the current of the winding of the traction machine M1, the second voltage is the voltage of the winding of the traction machine M1, the turns ratio of the three-phase transformer T1 is N:1. If the second current is N times the first current and the second voltage is 1 / N of the first voltage, it is determined that the closing state of the star connection contactor KM1 is normal, otherwise it is determined that the closing state of the star connection contactor KM1 is abnormal. Control the star connection contactor KM1 to disconnect, and obtain the second current and the second voltage. If the second current and the second voltage are 0, it is determined that the disconnection state of the star connection contactor KM1 is normal, otherwise it is determined that the disconnection state of the star connection contactor KM1 is abnormal. When it is determined that both the closing state and the disconnection state of the star connection contactor KM1 are normal, it is confirmed that the function of the star connection contactor KM1 is normal. During the detection process, the windings of the traction machine are short-circuited by closing the star connection contactor KM1. Due to the existence of the three-phase transformer T1, it will not cause a short circuit of the test power supply module. At the same time, the three-phase transformer T1 makes there be a specific ratio relationship between the first voltage and the second voltage, and between the first current and the second current, making the detection result judgment more accurate, realizing the detection of the reliability of the star connection contactor KM1, without the need for the elevator to coast, and without the need to test on specific floors of the elevator. The method is simple and efficient.

[0034] As Figure 2 shown, the elevator star connection detection method according to the third aspect embodiment of the present invention includes:

[0035] S100. Stop supplying power to the traction machine M1 and control the star connection contactor to close;

[0036] S200. The test power supply module inputs three-phase alternating current to the three-phase transformer T1, and obtains the first current, the first voltage, the second current and the second voltage. The first current is the current of the primary side winding of the three-phase transformer T1, the first voltage is the voltage of the primary side winding of the three-phase transformer T1, the second current is the current of the winding of the traction machine M1, the second voltage is the voltage of the winding of the traction machine M1, and the turns ratio of the three-phase transformer T1 is N:1;

[0037] S300. If the second current is N times the first current and the second voltage is 1 / N of the first voltage, it is determined that the closing state of the star connection contactor KM1 is normal, otherwise it is determined that the closing state of the star connection contactor KM1 is abnormal; when the closing state of the star connection contactor KM1 is abnormal, an alarm signal is issued and the elevator stops running;

[0038] S400. Control the sealing star contactor KM1 to disconnect, obtain the second current and the second voltage. If the second current and the second voltage are 0, it is determined that the disconnection state of the sealing star contactor KM1 is normal; otherwise, it is determined that the disconnection state of the sealing star contactor KM1 is abnormal. When the disconnection state of the sealing star contactor KM1 is abnormal, an alarm signal is issued and the elevator stops running.

[0039] S500. When it is determined that both the closing state and the disconnection state of the sealing star contactor KM1 are normal, it is confirmed that the function of the sealing star contactor KM1 is normal.

[0040] By stopping the power supply to the traction machine M1, controlling the sealing star contactor to close, testing the three-phase alternating current input by the power supply module to the three-phase transformer T1, and obtaining the first current, the first voltage, the second current and the second voltage. The first current is the current of the primary side winding of the three-phase transformer T1, the first voltage is the voltage of the primary side winding of the three-phase transformer T1, the second current is the current of the winding of the traction machine M1, and the second voltage is the voltage of the winding of the traction machine M1. The turns ratio of the three-phase transformer T1 is N:1. If the second current is N times the first current and the second voltage is 1 / N of the first voltage, it is determined that the closing state of the sealing star contactor KM1 is normal; otherwise, it is determined that the closing state of the sealing star contactor KM1 is abnormal. Control the sealing star contactor KM1 to disconnect, obtain the second current and the second voltage. If the second current and the second voltage are 0, it is determined that the disconnection state of the sealing star contactor KM1 is normal; otherwise, it is determined that the disconnection state of the sealing star contactor KM1 is abnormal. When it is determined that both the closing state and the disconnection state of the sealing star contactor KM1 are normal, it is confirmed that the function of the sealing star contactor KM1 is normal. During the detection process, the windings of the traction machine are short-circuited by the closing of the sealing star contactor KM1. Due to the presence of the three-phase transformer T1, it will not cause a short circuit of the test power supply module. At the same time, the three-phase transformer T1 makes there be a specific ratio relationship between the first voltage and the second voltage, and the first current and the second current, making the detection result judgment more accurate, realizing the detection of the reliability of the sealing star contactor KM1, without the need for the elevator to slip, and without the need to test at specific floors of the elevator. The method is simple and efficient.

[0041] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made without departing from the spirit of the present invention within the knowledge scope of those of ordinary skill in the art.

Claims

1. Elevator star connection detection system, characterized in that, Comprising: A control module; A traction machine, wherein the output end of the control module is connected to the winding of the traction machine for supplying power to the traction machine; A star connection contactor, wherein the output end of the control module is connected to the control end of the star connection contactor for controlling the closing or opening of the star connection contactor; A test power supply module, wherein the output end of the control module is connected to the control end of the test power supply module for controlling the test power supply module to output three-phase alternating current; A three-phase transformer, wherein the output end of the test power supply module is connected to the primary side winding of the three-phase transformer, the secondary side winding of the three-phase transformer is connected to one end of the star connection contactor, and the other end of the star connection contactor is connected to the winding of the traction machine; A current and voltage detection module, which is used for detecting the voltage and current of the winding of the traction machine, the output end of the current and voltage detection module is connected to the input end of the control module, the control module controls the closing or opening of the star connection contactor, the current and voltage detection module detects the voltage and current of the winding of the traction machine, the control module judges whether the voltage and current of the winding of the traction machine are preset values, if the voltage and current of the winding of the traction machine are both preset values, then it is confirmed that the star connection contactor is normal; The test power supply module is a frequency modulation and voltage regulation module, the input end of the frequency modulation and voltage regulation module is used for connecting an external power supply, the output end of the frequency modulation and voltage regulation module is connected to the primary side winding of the three-phase transformer, and the output end of the control module is connected to the control end of the frequency modulation and voltage regulation module; The control module includes a first control module and a second control module, the output end of the first control module is connected to the winding of the traction machine for supplying power to the traction machine, the output end of the second control module is connected to the control end of the test power supply module, the output end of the current and voltage detection module is connected to the input end of the second control module, and the first control module is connected to the second control module.

2. The elevator star connection detection system according to claim 1, wherein: It further includes a communication module, the second control module is communicatively connected to the first control module through the communication module, and the second control module is communicatively connected to the current and voltage detection module through the communication module.

3. The elevator star connection detection system according to claim 1, characterized in that: The star connection contactor is a normally closed star connection contactor.

4. The elevator star connection detection system according to claim 1, wherein: The star connection contactor is a normally open star connection contactor.

5. An elevator, characterized in that, Comprising: The elevator star connection detection system according to any one of claims 1 to 4.

6. Elevator star connection detection method, characterized in that, Applied to the elevator star connection detection system according to any one of claims 1 to 4, the method includes: Stop supplying power to the traction machine and control the star connection contactor to close; The test power supply module inputs three-phase alternating current to the three-phase transformer, and obtains a first current, a first voltage, a second current and a second voltage. The first current is the current of the primary side winding of the three-phase transformer, the first voltage is the voltage of the primary side winding of the three-phase transformer, the second current is the current of the winding of the traction machine, the second voltage is the voltage of the winding of the traction machine, and the turns ratio of the three-phase transformer is N:1; If the second current is N times the first current and the second voltage is 1 / N of the first voltage, then it is judged that the closing state of the star connection contactor is normal, otherwise it is judged that the closing state of the star connection contactor is abnormal; Control the star connection contactor to disconnect, obtain the second current and the second voltage. If the second current and the second voltage are 0, it is determined that the disconnection state of the star connection contactor is normal; otherwise, it is determined that the disconnection state of the star connection contactor is abnormal. When it is determined that both the closing state and the opening state of the star connection contactor are normal, it is confirmed that the function of the star connection contactor is normal.

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