High-precision steering system testing device

Abstract

The invention discloses a high-precision steering system test device, and relates to the field of automobile part tests, and the test device comprises an electric power steering system performance test bench, a drive motor and a load motor. When the electric power steering system performance test bench is used, the upper computer of the electric power steering system performance test bench simulates various input signals in a vehicle operation environment through a preset program, such as a variable vehicle speed and a variable vehicle load, and the load of a high-precision load motor is changed in real time in a test; through a vector control method, three-phase current is solved, the three-phase current is converted into a two-axis system, then an angle is converted, a voltage vector is determined, and an orthogonal voltage vector and an expected voltage vector are obtained, so that a motor is driven to provide real-time variable steering wheel torque and rotation angle signals, and the steering angle, the steering torque, the consumption current and other parameters of a steering system are fed back. Performance and functionality of the steering system are evaluated.

Description

Technical Field

[0001] The invention relates to the field of automobile parts testing, in particular to a high-precision steering system testing device. Background Art

[0002] Traditional steering system test equipment uses mechanical loading or hydraulic loading to apply a certain force or torque to the steering system to test the performance indicators of the steering system, focusing on steering force, steering response speed, etc. During the test, conditional parameters such as load, steering speed, and vehicle speed are fixed values, and dynamic changes of conditional parameters cannot be achieved. Depending on the product type of the steering gear and steering column, traditional steering system test equipment focuses on the performance of a single component and is mostly a special test device, which only uses different fixtures and connectors to achieve conversion testing.

[0003] However, traditional steering system test equipment cannot cope with complex working conditions. For example, as the vehicle speed changes, the load changes accordingly. It is impossible to test the steering system performance under different steering speeds. It is impossible to perform functional tests on the steering system, such as speed-dependent power assistance and active return. Mechanical or hydraulic loading has limited accuracy and response speed, which has a certain impact on the accuracy of input and output data. Special test equipment is limited in the types of products that can be used. It is impossible to achieve system-level tests such as steering gear and steering column linkage tests and rear-wheel steering system tests. Therefore, a high-precision steering system test device is urgently needed. Summary of the invention

[0004] The purpose of the present invention is to solve the problems that the existing traditional steering system test device cannot cope with complex working conditions, such as the load changes accordingly with the change of vehicle speed, and cannot test the steering system performance under different steering speeds, and cannot perform functional tests of the steering system, such as speed-dependent power assistance, active return, etc. Mechanical or hydraulic loading, limited accuracy and response speed have a certain impact on the accuracy of input and output data, and special test devices have limited corresponding product types, and cannot realize system-level tests such as steering gear and steering column linkage, rear-wheel steering system tests, etc., and provide a high-precision steering system test device.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a high-precision steering system test device, the test device comprising: an electric power steering system performance test bench, a drive motor and a load motor.

[0006] Preferably, the electric power steering system performance test bench comprises a device base plate, a steering gear fixing fixture, a steering column fixing fixture, a steering gear and a steering column.

[0007] Preferably, the steering gear fixing clamp is connected to the device bottom plate, and the steering gear fixing clamp is used to fix the steering gear; the steering column fixing clamp is connected to the device bottom plate by bolts, and the steering column fixing clamp is located at the rear side of the steering gear fixing clamp, and the steering column fixing clamp is used to fix the steering column, and the steering gear and steering column are connected by an intermediate shaft.

[0008] Preferably, the drive motor is located at the rear side of the steering column fixing fixture, and the drive motor is connected to the steering column input shaft.

[0009] Preferably, the driving motor vector control method comprises the following steps: Step 1: Calculate the third phase current: Measure the three-phase stator current i a， i b， i c ; Step 2: Convert the 2-axis system: convert the three-phase current to the 2-axis system; Step 3: Transformation Angle: Rotate the 2-axis system to align with the rotor flux according to the electrical angle (transformation angle) calculated by the previous iteration of the control loop; Step 4: Voltage vector: The error signal is generated by i α and i β The actual value is compared with the respective reference value; Step 5. Use the new transformation angle to obtain the orthogonal voltage: Estimate the new transformation angle, where v α 、v β 、i α 、i β is the input parameter; Step 6. Expected voltage vector: v α and v β After inverse transformation, the three-phase value v a 、v b 、v c .

[0010] Preferably, the three-phase stator current relationship is as follows: a +i b +i c =0, and the third-phase stator current can be obtained by measuring the two currents according to the formula. The two-axis current and i α and i β , which are measured by i a ,i b ,i c The value is obtained through coordinate transformation. From the perspective of the stator, i α and i β are time-varying current values ​​that are orthogonal to each other.

[0011] Preferably, in step three, iα and i β The variables can be transformed to obtain i d and i q ,i d and i q is the orthogonal current in the rotating coordinate system.

[0012] Preferably, in the step 4, i d The reference value controls the rotor flux, i q The reference value controls the torque of the motor. The error signal is the input of the PI (D) controller. The output of the controller is v d and v q , which is the voltage vector to be applied to the motor.

[0013] Preferably, in step 5, the new transformation angle obtained can be used to know the position of the next voltage vector of the vector control algorithm. In step 6, the three-phase voltage value v a 、v b 、v c It can be used to calculate a new PWM duty cycle to generate the desired voltage vector.

[0014] Compared with the prior art, the present invention has the following beneficial effects: When the present invention is used, the host computer of the electric power steering system performance test bench implements various input signals in the simulated vehicle operating environment through a preset program, such as a variable vehicle speed and a variable vehicle load, to a high-precision load motor, and changes the load in real time during the test; and through a vector control method, the three-phase current is obtained, the three-phase current is converted to a 2-axis system, and then the angle is changed, the voltage vector is determined, and the orthogonal voltage and the expected voltage vector are obtained, so as to drive the motor to provide a real-time variable steering wheel torque and rotation angle signal, and the performance and function of the steering system are evaluated by feeding back parameters such as the steering angle, steering torque, and current consumption of the steering system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic structural diagram of the electric power steering system of the present invention; Figure 2 It is a schematic diagram of the calculation steps of the micro control unit of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] See also Figure 1-Figure 2 , a high-precision steering system test device, the test device includes: an electric power steering system performance test bench, a drive motor and a load motor.

[0018] The electric power steering system performance test bench comprises a device bottom plate, a steering gear fixing fixture, a steering column fixing fixture, a steering gear and a steering column.

[0019] The steering gear fixing fixture is connected to the device bottom plate, and the steering gear fixing fixture is used to fix the steering gear; the steering column fixing fixture is connected to the device bottom plate by bolts, and the steering column fixing fixture is located at the rear side of the steering gear fixing fixture, and the steering column fixing fixture is used to fix the steering column. The steering gear and the steering column are connected by an intermediate shaft, and the steering gear outer tie rod is coaxially connected to the high-precision load motors on both sides of the device bottom plate through a connector to ensure a 100% load rate.

[0020] The driving motor is located at the rear side of the steering column fixing fixture, and the driving motor is connected to the steering column input shaft.

[0021] The driving motor vector control method comprises the following steps: Step 1: Calculate the third phase current: Measure the three-phase stator current i a， i b， i c ; Step 2: Convert the 2-axis system: convert the three-phase current to the 2-axis system; Step 3: Transformation Angle: Rotate the 2-axis system to align with the rotor flux according to the electrical angle (transformation angle) calculated by the previous iteration of the control loop; Step 4: Voltage vector: The error signal is generated by i α and i β The actual value is compared with the respective reference value; Step 5. Use the new transformation angle to obtain the orthogonal voltage: Estimate the new transformation angle, where v α 、v β 、i α 、i β is the input parameter; Step 6. Expected voltage vector: v α and v β After inverse transformation, the three-phase value v a 、v b 、v c .

[0022] The three-phase stator current relationship is as follows: a +i b +i c=0, and the third-phase stator current can be obtained by measuring the two currents according to the formula. The two-axis current and i α and i β , which are measured by i a ,i b ,i c The value is obtained through coordinate transformation. From the perspective of the stator, i α and i β are time-varying current values ​​that are orthogonal to each other.

[0023] In the step 3, i α and i β The variables can be transformed to obtain i d and i q ,i d and i q is the orthogonal current in the rotating coordinate system.

[0024] In the step 4, i d The reference value controls the rotor flux, i q The reference value controls the torque of the motor. The error signal is the input of the PI (D) controller. The output of the controller is v d and v q , which is the voltage vector to be applied to the motor.

[0025] In step 5, the new transformation angle obtained can be used to know the position of the next voltage vector of the vector control algorithm. In step 6, the three-phase voltage value v a 、v b 、v c It can be used to calculate a new PWM duty cycle to generate the desired voltage vector.

[0026] The upper computer of the electric power steering system performance test bench implements various input signals (such as variable vehicle speed and variable vehicle load) in the simulated vehicle operating environment to the high-precision load motor through a preset program, and changes the load in real time during the test; and provides real-time variable steering wheel torque and rotation angle signals to the drive motor, and evaluates the performance and function of the steering system by feeding back the steering angle, steering torque, current consumption and other parameters of the steering system.

[0027] The drive motor provides the steering torque and steering speed that simulate the steering wheel of a real car. First, calculate the third-phase current: measure the three-phase stator current i a， i b， i c , transform the three-phase current to the 2-axis system, and this conversion yields i d and i q ,i d and i qis the orthogonal current in the rotating coordinate system, and then the two-axis system is rotated to align with the rotor flux according to the electrical angle (transformation angle) calculated in the previous iteration of the control loop, i α and i β The variables can be transformed to obtain i d and i q ,i d and i q is the orthogonal current in the rotating coordinate system. Under steady-state conditions, i d and i q is a constant, then the error signal is given by α and i β The actual value is compared with the respective reference value to obtain, i d The reference value controls the rotor flux, i q The reference value controls the motor torque, and finally, estimates the new transformation angle, where v α 、v β 、i α 、i β is the input parameter. The new transformation angle obtained can know the position of the next voltage vector of the vector control algorithm. By using the new angle, the output value of the PI(D) controller can be inverted to the stationary reference coordinate system. The calculated value will produce the next orthogonal voltage value v α 、v β , v α and v β After inverse transformation, the three-phase value v a 、v b 、v c , which can be used to calculate the new PWM duty cycle to generate the desired voltage vector.

[0028] Working principle: When the present invention is used, the host computer of the electric power steering system performance test bench implements various input signals in the simulated vehicle operating environment through a preset program, such as variable vehicle speed and variable vehicle load, to the high-precision load motor, and changes the load in real time during the test; and through the vector control method, provides real-time variable steering wheel torque and rotation angle signals to the drive motor, and evaluates the performance and function of the steering system by feeding back the steering angle, steering torque, current consumption and other parameters of the steering system. The drive motor provides steering torque and steering speed that simulate the steering wheel of a real vehicle. First, calculate the third-phase current: measure the three-phase stator current i a， i b， i c , transform the three-phase current to the 2-axis system, and this conversion yields i d and i q ,i d and i qis the orthogonal current in the rotating coordinate system, and then the two-axis system is rotated to align with the rotor flux according to the electrical angle (transformation angle) calculated in the previous iteration of the control loop, i α and i β The variables can be transformed to obtain i d and i q ,i d and i q is the orthogonal current in the rotating coordinate system. Under steady-state conditions, i d and i q is a constant, then the error signal is given by α and i β The actual value is compared with the respective reference value to obtain, i d The reference value controls the rotor flux, i q The reference value controls the motor torque, and finally, estimates the new transformation angle, where v α 、v β 、i α 、i β is the input parameter. The new transformation angle obtained can know the position of the next voltage vector of the vector control algorithm. By using the new angle, the output value of the PI(D) controller can be inverted to the stationary reference coordinate system. The calculated value will produce the next orthogonal voltage value v α 、v β , v α and v β After inverse transformation, the three-phase value v a 、v b 、v c , which can be used to calculate the new PWM duty cycle to generate the desired voltage vector, and can realize the steering system performance and function test in the simulated real vehicle environment. The high-precision load motor can ensure the load accuracy and response speed, and is as close to the real vehicle test state as possible, thereby improving the accuracy of the test results, shortening the product development cycle, improving the test efficiency, and reducing the R&D cost.

[0029] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A high-precision steering system test device, characterized in that: The test device comprises: an electric power steering system performance test bench, a drive motor and a load motor.

2. A high-precision steering system test device according to claim 1, characterized in that: The electric power steering system performance test bench comprises a device bottom plate, a steering gear fixing fixture, a steering column fixing fixture, a steering gear and a steering column.

3. A high-precision steering system test device according to claim 2, characterized in that: The steering gear fixing fixture is connected to the device bottom plate, and the steering gear fixing fixture is used to fix the steering gear; the steering column fixing fixture is connected to the device bottom plate by bolts, and the steering column fixing fixture is located at the rear side of the steering gear fixing fixture, and the steering column fixing fixture is used to fix the steering column. The steering gear and the steering column are connected by an intermediate shaft.

4. A high-precision steering system test device according to claim 1, characterized in that: The driving motor is located at the rear side of the steering column fixing fixture, and the driving motor is connected to the steering column input shaft.

5. A high-precision steering system test device according to claim 4, characterized in that: The driving motor vector control method comprises the following steps: Step 1: Calculate the third phase current: Measure the three-phase stator current i a， i b， i c ; Step 2: Convert the 2-axis system: convert the three-phase current to the 2-axis system; Step 3: Transformation Angle: Rotate the 2-axis system to align with the rotor flux according to the electrical angle (transformation angle) calculated by the previous iteration of the control loop; Step 4: Voltage vector: The error signal is generated by i α and i β The actual value is compared with the respective reference value; Step 5. Use the new transformation angle to obtain the orthogonal voltage: Estimate the new transformation angle, where v α 、v β 、i α 、i β is the input parameter; Step 6. Expected voltage vector: v α and v β After inverse transformation, the three-phase value v a 、v b 、v c .

6. A high-precision steering system test device according to claim 5, characterized in that: The three-phase stator current relationship is as follows: a +i b +i c =0, and the third-phase stator current can be obtained by measuring the two currents according to the formula. The two-axis current and i α and i β , which are measured by i a ,i b ,i c The value is obtained through coordinate transformation. From the perspective of the stator, i α and i β are time-varying current values ​​that are orthogonal to each other.

7. A high-precision steering system test device according to claim 5, characterized in that: In the step 3, i α and i β The variables can be transformed to obtain i d and i q ,i d and i q is the orthogonal current in the rotating coordinate system.

8. A high-precision steering system test device according to claim 5, characterized in that: In the step 4, i d The reference value controls the rotor flux, i q The reference value controls the torque of the motor. The error signal is the input of the PI (D) controller. The output of the controller is v d and v q , which is the voltage vector to be applied to the motor.

9. A high-precision steering system test device according to claim 5, characterized in that: In step 5, the new transformation angle obtained can be used to know the position of the next voltage vector of the vector control algorithm. In step 6, the three-phase voltage value v a 、v b 、v c It can be used to calculate a new PWM duty cycle to generate the desired voltage vector.

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