Device and method for automatically testing on-load abrasion of brake of permanent magnet variable pitch motor

Abstract

The invention discloses a device and method for automatically testing on-load abrasion of a brake of a permanent magnet variable-pitch motor, and relates to the technical field of permanent magnet variable-pitch motors, and the device comprises a tested permanent magnet variable-pitch motor, an external power supply, a flywheel disc, a frequency converter, a single-chip microcomputer, an upper computer and a communication serial port. The tested permanent magnet variable pitch motor is internally provided with a target brake for carrying out a wear test, the target brake is connected with an external power supply, and the test device provided by the scheme can verify whether the brake can meet the emergency braking requirement proposed by a customer or not in a project development stage; powerful data support is provided for safe operation of a variable pitch system, and huge economic loss caused by galloping accidents can be avoided; meanwhile, the device can be automatically controlled to complete the testing process in the whole process in cooperation with a testing program of an upper computer, the device has the functions of unattended operation, automatic counting and automatic data recording, and the functions are especially important under the condition that a client requires a large number of abrasion testing times.

Description

Technical Field

[0001] The invention relates to a device and method for automatically testing load wear of a brake of a permanent magnet variable pitch motor, belonging to the technical field of permanent magnet variable pitch motors. Background Art

[0002] The permanent magnet pitch motors used in wind turbines are generally equipped with brakes, and the brakes are required to be able to brake with load under some abnormal operating conditions. For example, if the permanent magnet pitch motor suddenly short-circuits, the pitch system will cut off the power supply, and the pitch motor will be unable to provide power to maintain the pitch capability. At this time, if the pitch motor brake cannot be used to emergency stop the pitch system rotor, the external wind will blow the blades and continue to accelerate, eventually causing a runaway accident, causing great losses to the pitch system. To avoid the above problems, pitch motor manufacturers will conduct durability wear tests on how many emergency stops the brakes equipped with a certain pitch motor allow, in order to evaluate whether they can meet the safety requirements of the pitch system for the brake.

[0003] Because the pitch system shafting moment of inertia itself has certain requirements, when the test bench is set up with a load machine, if the load machine needs to output the customer's external load, its rotor moment of inertia is too large, and it cannot ensure that the shafting inertia meets the actual operating conditions of the pitch system. Therefore, the test bench cannot be equipped with a target load machine that meets the actual requirements. Without a load machine, how can the test bench provide load torque during the test? And how can the test bench reverse the brake in the latter part of the test to obtain the dynamic braking torque after the brake reaches a certain number of wear times? These become problems.

[0004] Without a load machine on the test bench, a torque sensor cannot be installed on the test bench. This is because the torque sensor needs to accurately measure the braking torque of the brake, which is located inside the test machine, so it cannot be installed there. Furthermore, if the torque sensor is placed at the rear of the test bench, the braking torque generated by the brake cannot be obtained. Therefore, without a torque sensor, how to obtain the actual speed of the shaft system during operation and the load torque data, as well as how to obtain the dynamic braking torque data of the brake at the end of the test, become problems.

[0005] Wear testing of brakes is a durability test. The testing process is complicated and the number of tests is too many. It relies on manual operation, monitoring, and data recording, which is time-consuming and labor-intensive. In addition, if human errors occur during the test, it is easy to cause safety accidents. Therefore, solutions are needed to solve the above problems. Summary of the Invention

[0006] In view of the above-mentioned technical problems, the purpose of the present invention is to propose an automatic test device and method for load wear of the brake of a permanent magnet variable pitch motor.

[0007] The technical solution of the present invention is achieved as follows: the automatic test device for load wear of the brake of the permanent magnet variable pitch motor comprises: the permanent magnet variable pitch motor to be tested, an external power supply, a flywheel, a frequency converter, a single chip microcomputer, a host computer and a communication serial port;

[0008] The tested permanent magnet variable pitch motor is internally provided with a target brake for wear testing, and the target brake is connected to an external power supply, and the external power supply is used to drive the target brake to release or engage; the flywheel is mounted on the rotating shaft of the tested permanent magnet variable pitch motor;

[0009] The frequency converter is matched with the permanent magnet variable pitch motor under test, and the frequency converter provides the current and voltage required for the test of the permanent magnet variable pitch motor under test. The frequency converter can switch to a torque mode or a speed control mode according to different test contents to drive the permanent magnet variable pitch motor under test to operate;

[0010] The single-chip microcomputer is electrically connected to the external power supply and the frequency converter. The single-chip microcomputer is used to control the on and off of the external power supply and the frequency converter. The host computer establishes a communication connection with the single-chip microcomputer through a communication serial port and exchanges information;

[0011] The frequency converter is electrically connected to the communication serial port, and the current and voltage data of the frequency converter during operation are uploaded to the host computer through the communication serial port.

[0012] Preferably, the host computer is provided with a control program for performing a wear test on the target brake.

[0013] The present invention also provides a method for testing load wear of a brake of a permanent magnet pitch motor, comprising the following steps:

[0014] S1, the host computer sends a test start signal to the single-chip microcomputer, and the single-chip microcomputer gives the target brake an instruction to connect the external power supply, and the target brake is energized and released;

[0015] In step S2, the MCU gives the inverter a start command, and the inverter turns on the torque mode. The inverter controls the tested permanent magnet variable pitch motor to start at no-load, and then increases the speed to the speed required for emergency braking of the target brake. The inverter limits the tested permanent magnet variable pitch motor to this speed and maintains it. The no-load voltage provided to the tested permanent magnet variable pitch motor at this time is uploaded to the host computer through the communication serial port, and the host computer synchronously displays and records it.

[0016] In step S3, the single-chip microcomputer issues a command to shut down the external power supply, and the target brake quickly powers off and engages, generating a braking torque on the shaft of the permanent magnet variable pitch motor under test. When the frequency converter detects that there is a braking torque on the shaft, the frequency converter quickly provides current to the permanent magnet variable pitch motor under test in the torque mode, generating a load torque on the shaft in the opposite direction of the braking torque. The braking torque overcomes the load torque on the shaft and decelerates the shaft, eventually bringing the shaft to a complete stop. During this process, the current data provided by the frequency converter to the permanent magnet variable pitch motor under test is uploaded to the host computer through the communication serial port, and is synchronously displayed and recorded by the host computer.

[0017] S4, after a specified time interval, repeat the test process of steps S1 to S3 to enter the next cycle test; each time a cycle test is performed, the counter reading of the host computer is increased by one until the counter reading of the host computer reaches a predetermined value, and the cycle test ends.

[0018] Preferably, during the cyclic test, the host computer continuously records the voltage, current and operation number data of the inverter, and synchronously displays and records the voltage, current and operation number data.

[0019] Preferably, in step S4, the designated time interval is used for heat dissipation of the target brake.

[0020] Preferably, after the cycle test in step S4 is completed, the following steps are further included:

[0021] S5, the host computer sends a command to the single-chip microcomputer, which controls the external power supply to turn off, so that the target brake is in the power-off braking state;

[0022] S6, the operating mode of the frequency converter is changed to the speed control mode, the frequency converter is started, the frequency converter provides current to the permanent magnet variable pitch motor under test, and gradually increases the current, so that the rotating shaft of the permanent magnet variable pitch motor under test obtains a gradually increasing torque to overcome the braking torque of the target brake, until the increased current can make the rotating shaft of the permanent magnet variable pitch motor under test start to rotate and reach a stable running state; the host computer reads and records the current signal and voltage signal of the frequency converter; determines whether the speed of the rotating shaft reaches the speed required for the test through the voltage signal, and determines the dynamic braking torque of the target brake through the current signal;

[0023] S7, remove the target brake, measure the thickness of the brake disc, and calculate the difference between before and after measurement;

[0024] S8 , combining the wear amount of the target brake obtained after the cyclic test of steps S1 to S4 and the dynamic braking torque of the target brake obtained in steps S5 to S6 , comprehensively judging whether the target brake meets the prescribed wear life requirement.

[0025] Preferably, before starting step S1, preparation work for the load characteristic curve of the tested permanent magnet variable pitch motor is required to calibrate in advance the parameters of various operating conditions that occur in steps S2, S3, and S6 when the inverter and the tested permanent magnet variable pitch motor are jointly operated.

[0026] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0027] 1. The test device provided by the present invention can verify whether the brake can meet the emergency braking requirements proposed by the customer during the project development stage, provide strong data support for the safe operation of the variable pitch system, and avoid the huge economic losses caused by runaway accidents; at the same time, in conjunction with the host computer test program, the device can be automatically controlled to complete the test process, with unmanned operation, automatic counting, and automatic data recording functions. This function is especially important when the customer requires a large number of wear tests.

[0028] 2. A frequency converter is used to provide current and voltage to the permanent magnet variable pitch motor under test, thereby generating the required load torque and speed to simulate the working conditions caused by the blades being blown by the wind. The entire test process can be carried out in the laboratory with simple operation, without consuming a large number of test personnel and test sites, and is more economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in describing the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without any creative work.

[0030] Attachment Figure 1 This is a schematic structural diagram of an automatic load wear test device for a permanent magnet pitch motor brake according to a first embodiment of the present invention;

[0031] Attachment Figure 2 This is a flow chart of a target brake wear test of a method for testing brake wear under load of a permanent magnet variable pitch motor according to a second embodiment of the present invention;

[0032] Attachment Figure 3 This is a flowchart of a target brake post-wear braking torque test of a method for testing load wear of a brake of a permanent magnet pitch motor according to a second embodiment of the present invention.

[0033] In the figure: 1. Permanent magnet variable pitch motor under test; 11. Target brake; 12. Rotating shaft; 2. External power supply; 3. Flywheel; 4. Frequency converter; 5. Single chip microcomputer; 6. Host computer; 7. Communication serial port. DETAILED DESCRIPTION

[0034] To make the technical problems solved, the technical solutions adopted, and the technical effects achieved by the present invention more clearly understood, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the described embodiments are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that terms such as "center," "upper," "lower," "left," "right," "vertical," "upright," "horizontal," "inner," and "outer" indicate positions or relationships based on the positions or relationships shown in the accompanying drawings. These terms are used solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0036] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed or detachable connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0037] The permanent magnet variable pitch motor of the present invention is used in the variable pitch system of a wind turbine generator set. Based on the variable pitch system, the brake installed in the permanent magnet variable pitch motor needs to meet the following conditions:

[0038] (1) The system's moment of inertia is not less than a certain value;

[0039] (2) The reverse torque when the external load is applied to the brake is not less than a certain value;

[0040] (3) The speed should not be lower than a certain value during emergency braking;

[0041] (4) The dynamic braking torque of the brake at this limit speed must be greater than the external reverse torque, so that while the system offsets the external reverse torque, the remaining braking torque can quickly stop the rotating system;

[0042] (5) The number of emergency braking times shall not be less than a certain value within the required service life of the brake;

[0043] (6) After the number of emergency braking reaches the requirement, the torque in this state shall not be less than a certain value so that the brake can offset the external reverse torque while the remaining braking torque can still stop the rotating system quickly.

[0044] In summary, the present invention provides an automatic test device and method for load wear of the brake of a permanent magnet pitch motor, so as to evaluate whether the above requirements of the pitch system for the brake are met.

[0045] Example 1

[0046] As attached Figure 1 As shown, the automatic test device for load wear of the brake of a permanent magnet variable pitch motor includes: a permanent magnet variable pitch motor 1 to be tested, an external power supply 2, a flywheel 3, a frequency converter 4, a single-chip microcomputer 5, a host computer 6 and a communication serial port 7; a target brake 11 for wear test is provided inside the permanent magnet variable pitch motor 1 to be tested, and the target brake 11 is connected to the external power supply 2, and the external power supply 2 is used to drive the target brake 11 to release or attract; wherein, the external power supply 2 provides DC power to the target brake 11 separately.

[0047] The flywheel 3 is mounted on the rotating shaft 12 of the permanent magnet pitch motor 1 under test, and plays the role of matching the system's rotational inertia. The flywheel 3 and the permanent magnet pitch motor 1 under test together constitute the rotational inertia required by the pitch system to simulate the actual operating state of the pitch system.

[0048] The frequency converter 4 is matched with the permanent magnet variable pitch motor 1 under test. The frequency converter 4 provides the current and voltage required for the test for the permanent magnet variable pitch motor 1 under test. The frequency converter 4 can switch to the torque mode or the speed control mode (the definitions of the torque mode and the speed control mode are described in the following embodiment 2) according to different test contents to drive the permanent magnet variable pitch motor 1 under test to operate.

[0049] The single chip microcomputer 5 is electrically connected to the external power supply 2 and the frequency converter 4. The single chip microcomputer 5 is used to control the on and off of the external power supply 2 and the frequency converter 4, and further control the power-on operation and power-off stop of the external power supply 2 and the frequency converter 4.

[0050] The host computer and the single-chip microcomputer establish a communication connection through the communication serial port and exchange information; among them, the inverter is electrically connected to the communication serial port, and the current and voltage data of the inverter during operation are uploaded to the host computer through the communication serial port.

[0051] In this embodiment, the host computer 6 is provided with a control program for performing a wear test on the target brake 11 .

[0052] Example 2

[0053] A method for testing load wear of a brake of a permanent magnet variable pitch motor adopts the above-mentioned load wear testing device for the brake of a permanent magnet variable pitch motor.

[0054] First, before starting the test, it is necessary to use a common bench with a load machine to prepare the load characteristic curve of the tested permanent magnet pitch motor 1, so as to calibrate in advance the parameters of various operating conditions that appear in the following S2, S3, and S6 steps when the inverter 4 and the tested permanent magnet pitch motor 1 are jointly operated. The load characteristic curve specifically includes:

[0055] (1) At different specific speeds, when the tested permanent magnet variable pitch motor 1 is running at no-load, the no-load voltage of the stator side of the tested permanent magnet variable pitch motor 1 input by the inverter 4 is measured and recorded to provide data reference for the no-load operating condition of the tested permanent magnet variable pitch motor 1 in the subsequent step S2.

[0056] (2) At different specific speeds, the inverter 4 adopts a torque control mode for the permanent magnet variable pitch motor 1 under test. Based on the same load torque, the current and voltage input by the inverter 4 to the permanent magnet variable pitch motor 1 under test are measured and recorded; this provides a data reference for the load torque operating condition of the permanent magnet variable pitch motor 1 under test in the subsequent step S3.

[0057] (3) At different specific speeds, the frequency converter 4 adopts a speed control mode for the permanent magnet variable pitch motor 1 under test. When the load machine gradually increases the load torque on the shaft, the current values ​​provided by the frequency converter 4 to the permanent magnet variable pitch motor 1 and the stator under different load torques are measured and recorded to provide data reference for the load torque operating condition of the permanent magnet variable pitch motor 1 under test in the subsequent step S6.

[0058] During the above preparation process, the torque and speed parameters involved can be measured by the torque sensor built on the test bench; during the test, the voltage and current parameters provided by the inverter 4 to the tested permanent magnet variable pitch motor 1 are synchronously uploaded to the host computer 6 for recording.

[0059] As attached Figure 2 As shown, the wear test of the target brake 11 during emergency braking is then performed, comprising the following steps:

[0060] S1, the host computer 6 sends a test start signal to the single chip microcomputer 5, and the single chip microcomputer 5 gives an instruction to connect the target brake 11 to the external power supply 2, and the target brake 11 is energized and released.

[0061] S2, the single-chip microcomputer 5 gives the inverter 4 a start instruction, the inverter 4 starts the torque mode, the inverter 4 controls the tested permanent magnet variable pitch motor 1 to start at no-load, and then speeds up to the speed required for emergency braking of the target brake 11. The inverter 4 limits the tested permanent magnet variable pitch motor 1 to this speed and maintains it, and uploads the no-load voltage provided to the tested permanent magnet variable pitch motor 1 at this time to the host computer 6 through the communication serial port 7, which is synchronously displayed and recorded by the host computer 6; the no-load voltage is used to confirm whether the rotating shaft 12 of the tested permanent magnet variable pitch motor 1 has reached the speed required for emergency braking.

[0062] Among them, torque mode means that when the load of the variable frequency motor changes, the motor speed is adjusted to keep the output torque unchanged. In torque mode, the motor speed will be adjusted according to the load requirements to keep the output torque stable. This mode is suitable for occasions where constant output torque needs to be maintained.

[0063] S3, the single-chip microcomputer 5 gives a shutdown instruction to the external power supply 2, the target brake 11 is quickly de-energized and attracted, generating a braking torque on the rotating shaft 12 of the permanent magnet variable pitch motor 1 under test. When the frequency converter 4 detects that there is a braking torque on the rotating shaft 12, the frequency converter 4 quickly provides current to the permanent magnet variable pitch motor 1 under test, so that a load torque opposite to the braking torque is generated on the rotating shaft 12. The braking torque overcomes the load torque on the rotating shaft and decelerates the rotating shaft, and finally the rotating shaft is completely stopped.

[0064] Among them, the load torque is an additional torque generated when the blades are blown by the wind. Therefore, a part of the braking torque generated by the target brake 11 when stopping the rotating shaft 12 is offset by the load torque, and the remaining braking torque stops the rotating shaft 12. In this process, although the target brake 11 stops the rotating shaft 12, in order to overcome the load torque and stop the rotating shaft 12 from the rotating state, it itself is also worn, thereby simulating the wear of the target brake 11 during emergency braking.

[0065] In this embodiment, when the inverter 4 is set to the torque mode, the inverter 4 will automatically detect whether there is a braking torque on the shaft 12. If there is a braking torque on the shaft 12, the inverter 4 will quickly provide a constant reverse load torque.

[0066] During this process, the current data provided by the inverter 4 to the permanent magnet variable pitch motor 1 under test is uploaded to the host computer 6 through the communication serial port 7, and is synchronously displayed and recorded by the host computer 6; the current data is used to determine whether the load torque of the permanent magnet variable pitch motor 1 under test on the rotating shaft meets the load torque required by the test at the specified speed.

[0067] S4, after a specified time interval, repeat the test process of steps S1 to S3 and enter the next cycle test. Each time a cycle test is performed, the counter reading of the host computer 6 is increased by one until the counter reading of the host computer 6 reaches a predetermined value, and the cycle test ends.

[0068] Among them, in step S4, a specified time interval is used for heat dissipation of the target brake 11 to ensure the accuracy of each cycle test and prevent the target brake 11 from overheating and burning. In this embodiment, the test time from step S1 to step S4, plus the intermediate interval heat dissipation time is 5 minutes.

[0069] During the cyclic test, the host computer 6 continuously records the voltage, current and operation times of the inverter 4, and synchronously displays and records the data for subsequent analysis and archiving by staff.

[0070] As attached Figure 3 As shown, finally, after the cycle test of step S4 is completed, it is necessary to perform a braking torque test on the target brake 11 that has undergone the wear test, which includes the following steps:

[0071] S5, the host computer 6 sends a command to the single chip microcomputer 5, and the single chip microcomputer 5 controls the external power supply 2 to be turned off, so that the target brake 11 is in a power-off braking state.

[0072] S6, the operating mode of the inverter 4 is changed to the speed control mode, and the inverter 4 is started. The inverter 4 provides current to the permanent magnet variable pitch motor 1 under test, and gradually increases the current so that the rotating shaft 12 of the permanent magnet variable pitch motor 1 under test obtains a gradually increasing torque to overcome the braking torque of the target brake 11, until the increased current can make the rotating shaft 12 of the permanent magnet variable pitch motor 1 under test start to rotate and reach a stable running state. The upper computer 6 reads and records the current signal and voltage signal of the inverter 4; judges whether the speed of the rotating shaft 12 reaches the speed required for the test through the voltage signal, and judges the dynamic braking torque of the target brake 11 through the current signal.

[0073] Among them, the speed control mode is a commonly used control mode of the inverter, which is suitable for occasions where the motor needs to run at a constant speed. In this mode, the inverter will adjust the motor speed according to the set frequency to achieve a constant speed. The advantages of this mode are high control stability and high speed accuracy, which can effectively ensure the constant speed of the motor.

[0074] S7, remove the target brake 11, measure the thickness of the brake disc, and calculate the difference between before and after the measurement.

[0075] S8 , combining the wear amount of the target brake obtained after the cyclic test of steps S1 to S4 and the dynamic braking torque of the target brake obtained in steps S5 to S6 , comprehensively judging whether the target brake meets the prescribed wear life requirement.

[0076] Among them, the dynamic braking torque of the target brake 11 after wear is used to evaluate whether the target brake 11 can still ensure its normal braking effect after a predetermined number of emergency brakings; and the wear amount of the target brake 11 after wear is used to evaluate whether the target brake 11 can still ensure a normal braking response time.

[0077] In summary, the automatic measuring device provided by the present invention can verify whether the brake can meet the emergency braking requirements proposed by the customer during the project development phase, providing strong data support for the safe operation of the variable pitch system and avoiding the huge economic losses caused by runaway accidents.

[0078] At the same time, in conjunction with the host computer test program, the device can be automatically controlled throughout the test process, with the ability to automatically count and record data without human supervision. This capability is particularly prominent when customers require a large number of wear tests.

[0079] In addition, the present invention uses a frequency converter 4 to provide current and voltage to the permanent magnet variable pitch motor 1 under test, thereby generating the required load torque and speed to simulate the working conditions caused by the blades being blown by the wind. The overall testing process can be carried out in the laboratory with simple operation, without consuming a large number of test personnel and test sites, and is more economical.

[0080] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. The automatic test device for the load wear of the brake of the permanent magnet variable pitch motor is characterized by: It includes: a permanent magnet variable pitch motor to be tested (1), an external power supply (2), a flywheel (3), a frequency converter (4), a single chip microcomputer (5), a host computer (6) and a communication serial port (7); The tested permanent magnet variable pitch motor (1) is provided with a target brake (11) for performing a wear test inside, the target brake (11) is connected to an external power supply (2), and the external power supply (2) is used to drive the target brake (11) to release or engage; the flywheel (3) is mounted on the rotating shaft (12) of the tested permanent magnet variable pitch motor (1); The frequency converter (4) is matched with the permanent magnet variable pitch motor (1) under test, and the frequency converter (4) provides the permanent magnet variable pitch motor (1) under test with current and voltage required for testing. The frequency converter (4) can be switched to a torque mode or a speed control mode according to different test contents to drive the permanent magnet variable pitch motor (1) under test to operate; The single-chip microcomputer (5) is electrically connected to the external power supply (2) and the frequency converter (4). The single-chip microcomputer (5) is used to control the on / off of the external power supply (2) and the frequency converter (4). The host computer (6) establishes a communication connection with the single-chip microcomputer (5) via a communication serial port (7) and performs information exchange. The frequency converter (4) is electrically connected to the communication serial port (7), and the current and voltage data of the frequency converter (4) during operation are uploaded to the host computer (6) via the communication serial port (7).

2. The automatic load wear test device for the brake of a permanent magnet variable pitch motor according to claim 1 is characterized in that: The host computer (6) is provided with a control program for performing a wear test on the target brake (11).

3. A method for testing the load wear of the brake of a permanent magnet variable pitch motor, using the automatic test device for load wear of the brake of a permanent magnet variable pitch motor according to any one of claims 1-2, characterized in that: The following steps are involved: S1, the host computer (6) sends a test start signal to the single chip microcomputer (5), and the single chip microcomputer (5) gives an instruction to connect the target brake (11) to the external power supply (2), and the target brake (11) is energized and released; S2, the single chip microcomputer (5) gives the inverter (4) a start instruction, the inverter (4) starts the torque mode, the inverter (4) controls the tested permanent magnet variable pitch motor (1) to start at no-load, and then increases the speed to the speed required by the target brake (11) during emergency braking. The inverter (4) limits the tested permanent magnet variable pitch motor (1) to the speed and maintains it, and uploads the no-load voltage provided to the tested permanent magnet variable pitch motor (1) at this time to the host computer (6) through the communication serial port (7), and the host computer (6) synchronously displays and records it; S3, the single chip microcomputer (5) gives a shutdown instruction for the external power supply (2), and the target brake (11) is quickly de-energized and engaged, generating a braking torque on the shaft (12) of the permanent magnet variable pitch motor (1) under test; when the frequency converter (4) detects that there is a braking torque on the shaft (12), the frequency converter (4) quickly provides current to the permanent magnet variable pitch motor (1) under test in a torque mode, so that a load torque opposite to the braking torque is generated on the shaft (12); the braking torque overcomes the load torque on the shaft (12) and decelerates the shaft (12), and finally completely stops the shaft (12); in this process, the current data provided by the frequency converter (4) to the permanent magnet variable pitch motor (1) under test is uploaded to the host computer (6) through the communication serial port (7), and is synchronously displayed and recorded by the host computer (6); S4, after a specified time interval, repeat the test process of steps S1 to S3 to enter the next cycle test; each time a cycle test is performed, the counter reading of the host computer (6) is increased by one until the counter reading of the host computer (6) reaches a predetermined value, and the cycle test ends.

4. The method for testing load wear of a brake of a permanent magnet variable pitch motor according to claim 3, characterized in that: During the cyclic test, the host computer (6) continuously records the voltage, current and operation number data of the frequency converter (4), and synchronously displays and records the voltage, current and operation number data.

5. The method for testing load wear of a brake of a permanent magnet variable pitch motor according to claim 3, characterized in that: In step S4, the designated time interval is used for heat dissipation of the target brake (11).

6. The method for testing load wear of a brake of a permanent magnet variable pitch motor according to claim 3, characterized in that: After the cycle test in step S4 is completed, the following steps are further included: S5, the host computer (6) sends a command to the single chip microcomputer (5), and the single chip microcomputer (5) controls the external power supply (2) to be turned off, so that the target brake (11) is in a power-off braking state; S6, the operation mode of the frequency converter (4) is changed to the speed control mode, the frequency converter (4) is started, the frequency converter (4) provides current to the permanent magnet variable pitch motor (1) under test, and gradually increases the current, so that the rotating shaft (12) of the permanent magnet variable pitch motor (1) under test obtains a gradually increasing torque to overcome the braking torque of the target brake (11), until the increased current can make the rotating shaft (12) of the permanent magnet variable pitch motor (1) under test start to rotate and reach a stable running state; the host computer (6) reads and records the current signal and voltage signal of the frequency converter (4); judges whether the speed of the rotating shaft (12) reaches the speed required for the test through the voltage signal, and judges the dynamic braking torque of the target brake (11) through the current signal; S7, dismantling the target brake (11), measuring the thickness of the brake disc, and calculating the difference between before and after the measurement; S8, combining the wear amount of the target brake (11) obtained after the cyclic test of steps S1 to S4 and the dynamic braking torque of the target brake (11) obtained in steps S5 to S6, comprehensively judge whether the target brake (11) meets the specified wear life requirements.

7. The method for testing load wear of a brake of a permanent magnet variable pitch motor according to claim 6, characterized in that: Before starting step S1, it is necessary to prepare the load characteristic curve of the permanent magnet pitch motor under test in order to calibrate in advance the parameters of various operating conditions that appear in steps S2, S3, and S6 when the inverter and the permanent magnet pitch motor under test are jointly operated.

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