Test device for torque fluctuation of EPS permanent magnet synchronous motor and use thereof

Abstract

The application discloses a device for testing torque fluctuation of an EPS permanent magnet synchronous motor and a use method thereof. The device comprises a test table, a permanent magnet synchronous motor to be tested, a servo motor, a torque sensor and a plurality of shaft couplings. The test table is provided with a first permanent magnet synchronous motor to be tested and a second permanent magnet synchronous motor to be tested in adjacency. The three-phase power supply lines of the first permanent magnet synchronous motor to be tested and the second permanent magnet synchronous motor to be tested are directly connected by a wire harness. The wire harness should be as short as possible to reduce the wiring resistance of the two permanent magnet synchronous motors to be tested. The first servo motor is set to a speed closed-loop control mode, and the second servo motor is set to a torque closed-loop control mode. The application cancels the mode that a controller (ECU) drives a motor to measure, utilizes two groups of permanent magnet synchronous motors to be tested to cooperate, guarantees the stability and accuracy of current output, and provides reliable guarantee for torque fluctuation measurement.

Description

Technical Field

[0001] This invention belongs to the technical field of testing electric power steering (EPS) systems for automobiles, and more specifically, it relates to a device for testing torque fluctuations of EPS permanent magnet synchronous motors and its usage. Background Technology

[0002] Currently, automotive electric power steering systems (EPS) commonly use permanent magnet synchronous motors (hereinafter referred to as "motors"). The torque fluctuations generated by the motor directly affect the performance of EPS. Therefore, it is necessary to measure the torque fluctuations of the motor as an important parameter so that the feedback can be used by the design department to revise the parameters.

[0003] Currently, both domestic and international methods use an ECU (Electronic Control Unit) to drive the motor for measurement. However, in practice, the following difficulties exist:

[0004] (1) When the controller inverts DC power into three-phase AC power, it is difficult to ensure that the voltage and current do not change. The so-called change will lead to an increase in the torque fluctuation of the motor, which may cause parameter misleading in motor development and manufacturing. At the same time, it is also difficult to distinguish whether the torque fluctuation is caused by motor factors or ECU factors.

[0005] (2) If you buy an EPS off the market, it is difficult to drive the EPS motor because there is no corresponding communication program, which makes it impossible to measure the torque fluctuation of the motor.

[0006] Therefore, both methods mentioned above inherently have certain drawbacks. How to accurately obtain the torque fluctuation value of a permanent magnet synchronous motor without using an ECU is a problem that industry professionals should consider. Summary of the Invention

[0007] Purpose of the invention: To address the shortcomings of existing tests on torque fluctuations in EPS permanent magnet synchronous motors, this invention utilizes the general principle that a motor can operate in both generator and motor modes. By controlling a servo motor to drive one motor, the power generated by the servo motor is supplied to another motor under test. By adjusting the load size, torque fluctuations under different currents can be obtained.

[0008] To achieve the aforementioned objectives, this invention provides a device for testing torque fluctuations in EPS permanent magnet synchronous motors and its usage. The device includes a test bench, a permanent magnet synchronous motor under test, a servo motor, a torque sensor, and several couplings. The test bench is configured with a first and a second permanent magnet synchronous motor under test adjacent to each other. The three-phase power lines of the first and second permanent magnet synchronous motors under test are directly connected by a wire harness. The wire harness should be as short as possible to minimize the connection resistance between the two motors under test.

[0009] An encoder and a first servo motor are installed at the end of the first permanent magnet synchronous motor to be tested away from the second permanent magnet synchronous motor to be tested. A coupling is installed between the first permanent magnet synchronous motor to be tested and the encoder, and a coupling is installed between the encoder and the first servo motor. A torque sensor and a second servo motor are installed at the end of the second permanent magnet synchronous motor to be tested away from the first permanent magnet synchronous motor to be tested. A coupling is installed between the second permanent magnet synchronous motor to be tested and the torque sensor, and a coupling is installed between the torque sensor and the second servo motor.

[0010] One method for testing the torque fluctuation of an EPS permanent magnet synchronous motor is as follows: First, the first servo motor is set to speed closed-loop control mode, and the second servo motor is set to torque closed-loop control mode.

[0011] At the start of the test, the speed of the first servo motor was slowly increased from 0 to 30 rpm, which was required to measure the torque fluctuation, and then remained stable.

[0012] The phase lines of the first permanent magnet synchronous motor under test and the second permanent magnet synchronous motor under test are directly connected. The current generated by the first permanent magnet synchronous motor under test driven by the first servo motor flows into the second permanent magnet synchronous motor under test. The second permanent magnet synchronous motor under test drives the second servo motor to rotate. The torque fluctuation of the first servo motor can be measured by the torque sensor.

[0013] Beneficial effects: Compared with existing technologies, the beneficial effects of this new process are:

[0014] (1) The present invention eliminates the method of measuring by driving the motor with the controller (ECU), which not only reduces the measurement expenses, but also avoids the voltage and current deviation when the controller (ECU) converts DC to three-phase AC, which leads to inaccurate torque fluctuation measurement.

[0015] (2) This invention utilizes the general principle that a motor can operate in both generator and motor modes. By using two sets of permanent magnet synchronous motors under test in coordination, the stability and accuracy of the current output are ensured, providing a reliable guarantee for the measurement of torque fluctuations. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a device for testing torque fluctuations in an EPS permanent magnet synchronous motor according to the present invention. Detailed Implementation

[0017] The following best practice example will be used to illustrate the technical solution in detail, but the scope of protection of the present invention is not limited to the described practice example.

[0018] like Figure 1As shown, an apparatus for testing torque fluctuation of an EPS permanent magnet synchronous motor includes a test bench 1, a permanent magnet synchronous motor under test, a servo motor, a torque sensor, and several couplings 5. A first permanent magnet synchronous motor 2A and a second permanent magnet synchronous motor 2B under test are arranged adjacent to each other on the test bench 1. The three-phase power lines of the first and second permanent magnet synchronous motors 2A and 2B are directly connected by a wire harness. An encoder 3 and a first servo motor 4A are arranged at the end of the first permanent magnet synchronous motor 2A away from the second permanent magnet synchronous motor 2B. A coupling 5 is arranged between the first permanent magnet synchronous motor 2A and the encoder 3, and between the encoder 3 and the first servo motor 4A. A torque sensor 6 and a second servo motor 4B are arranged at the end of the second permanent magnet synchronous motor 2B away from the first permanent magnet synchronous motor 2A. A coupling 5 is arranged between the second permanent magnet synchronous motor 2B and the torque sensor 6, and between the torque sensor 6 and the second servo motor 4B.

[0019] A method for testing torque fluctuation in an EPS permanent magnet synchronous motor, wherein the method is as follows during actual operation:

[0020] A. The first servo motor 4A is set to speed closed-loop control mode, and the second servo motor 4B is set to torque closed-loop control mode.

[0021] B. At the start of the test, the speed of the first servo motor 4A is slowly increased from 0 to the motor speed required to measure the torque fluctuation, which is 30 rpm, and then kept stable.

[0022] C. The phase lines of the first permanent magnet synchronous motor 2A under test and the second permanent magnet synchronous motor 2B under test are directly connected. The current generated by the first permanent magnet synchronous motor 2A under test driven by the first servo motor 4A flows into the second permanent magnet synchronous motor 2B under test. The second permanent magnet synchronous motor 2B under test drives the second servo motor 4B to rotate. The torque fluctuation of the first servo motor 4A can be measured by the torque sensor 6.

[0023] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A device for testing torque fluctuation of an EPS permanent magnet synchronous motor, comprising a test table (1), a permanent magnet synchronous motor to be tested, a servo motor, a torque sensor, and a plurality of shaft couplings (5), characterized in that: The test bench (1) is adjacent to the first to-be-tested permanent magnet synchronous motor (2A) and the second to-be-tested permanent magnet synchronous motor (2B), the three-phase power lines of the first to-be-tested permanent magnet synchronous motor (2A) and the second to-be-tested permanent magnet synchronous motor (2B) are directly connected by a wire harness, the first to-be-tested permanent magnet synchronous motor (2A) is provided with an encoder (3) and a first servo motor (4A) at one end away from the second to-be-tested permanent magnet synchronous motor (2B), a shaft coupling (5) is arranged between the first to-be-tested permanent magnet synchronous motor (2A) and the encoder (3), a shaft coupling (5) is arranged between the encoder (3) and the first servo motor (4A), a torque sensor (6) and a second servo motor (4B) are arranged at one end of the second to-be-tested permanent magnet synchronous motor (2B) away from the first to-be-tested permanent magnet synchronous motor (2A), a shaft coupling (5) is arranged between the second to-be-tested permanent magnet synchronous motor (2B) and the torque sensor (6), and a shaft coupling (5) is arranged between the torque sensor (6) and the second servo motor (4B), the first to-be-tested permanent magnet synchronous motor (2A) operates as a generator under the drive of the first servo motor (4A), and the second to-be-tested permanent magnet synchronous motor (2B) operates as a motor after receiving current.

2. A method of using the test device for torque ripple of the EPS permanent magnet synchronous motor as claimed in claim 1, characterized in that: The method is as follows: A. The first servo motor (4A) is set to a speed closed-loop control mode, and the second servo motor (4B) is set to a torque closed-loop control mode; B. At the beginning of the test, the speed of the first servo motor (4A) starts from 0 and slowly increases to 30 rpm, which is the motor speed required for measuring torque fluctuation, and remains stable; C. The phase lines of the first to-be-tested permanent magnet synchronous motor (2A) and the second to-be-tested permanent magnet synchronous motor (2B) are directly connected, the current generated by the first to-be-tested permanent magnet synchronous motor (2A) driven by the first servo motor (4A) flows into the second to-be-tested permanent magnet synchronous motor (2B), the second to-be-tested permanent magnet synchronous motor (2B) drives the second servo motor (4B) to rotate, the torque fluctuation of the first servo motor (4A) can be measured through the torque sensor (6), the first to-be-tested permanent magnet synchronous motor (2A) supplies power to the second to-be-tested permanent magnet synchronous motor (2B) as a generator, and the second to-be-tested permanent magnet synchronous motor (2B) drives the second servo motor (4B) as a motor.

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