Motor control method for reducing start-stop impact
By using active short circuit control during the motor shutdown stage to generate maximum negative torque acceleration stop, and using the angle position information of the last shutdown during startup for open-loop start, the motor start-stop impact problem is solved, vibration and noise are reduced, and control accuracy is improved.
Patent Information
- Application Number
- CN202411587022.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-02-25
AI Technical Summary
When the motor starts and stops, the start and stop impact caused by the mechanical gap causes vibration and noise, and the speed calculation accuracy is poor at low speed under the control of the position sensor, which worsens the mechanical impact problem.
Active short circuit control is used to control the motor to complete shutdown, and the maximum negative torque is generated during the shutdown phase to accelerate the shutdown, and open-loop start using the angle position information of the last shutdown during startup to reduce start-stop impact.
It effectively avoids mechanical impacts caused by poor speed calculation accuracy at low speeds, reduces vibration and noise caused by mechanical gaps, and improves the open-loop speed control accuracy during startup.
Smart Images
Figure CN119519518A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a motor control method for reducing start-stop impact, and belongs to the technical field of motor control. Background Art
[0002] When the motor output shaft is connected to a load with mechanical clearance such as a transmission mechanism or a pump body, there will often be mechanical impact when the motor starts and stops, causing large vibration and noise, and even reducing the life of the load mechanism. When the motor is controlled without a position sensor, the speed control accuracy is poor due to inaccurate calculation of the position recognition algorithm at low speeds, which further worsens the mechanical impact during the start-stop stage.
[0003] Common motor start-stop control methods to reduce start-stop impacts are mainly to try to apply a small starting current at startup to slowly eliminate the mechanical gap, and then increase the starting current to enter the normal starting process. When shutting down, the speed is always controlled to 0 speed in a closed loop to try to reduce the start-stop impact.
[0004] The existing starting control method attempts to apply a very small starting current for a period of time, which will cause the starting time to be longer. In addition, this open-loop control method cannot guarantee that the starting impact under all working conditions can be solved, and the effect is random.
[0005] The existing shutdown control method relies on accurate speed feedback at low speed, has poor adaptability in the situation of position sensorless control, and cannot completely avoid shutdown impact. Summary of the invention
[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a motor control method that reduces start-stop impact. Using active short-circuit control to completely stop the motor can avoid the problem of poor speed calculation accuracy at low speeds leading to unstable speed control and mechanical impact.
[0007] To achieve the above object, the present invention is implemented by adopting the following technical solutions: The present invention provides a motor control method for reducing start-stop impact, comprising: When the motor is in working state, obtaining the angular position information and the rotation speed information of the motor in real time; When the motor receives a stop command, if the stop command is a non-fault emergency stop command, the motor speed is reduced to a calibrated speed value according to the calibrated deceleration; Actively short-circuit the lower three bridges of the motor to generate maximum negative torque and accelerate shutdown; When the pre-calibrated duration is reached or the motor has completely stopped rotating, the active short-circuit control of the lower three bridges is terminated, and the angular position information of the motor at the last moment of the stop period is stored; When the motor is in a stopped state and receives a start command, the stored angle position information is sent to the motor open-loop start program, and the motor is started according to the sent angle position information.
[0008] Furthermore, if the stop instruction is a fault emergency stop instruction, a rapid shutdown procedure is executed.
[0009] Further, when the motor is in a stopped state and receives a start command, it is first determined whether the motor has an unresolved fault; If there are unresolved faults, the start command is blocked.
[0010] Furthermore, the motor starts open-loop control until the closed-loop sensorless control speed switching point is met, and then switches into sensorless control, detecting and updating the motor's angular position information and speed information based on the positionless sensor.
[0011] Furthermore, the calibrable speed value , the calculation formula is as follows: (10); Where R is the resistance of the stator in the motor; is the number of motor pole pairs, is the inductance component of the Q axis in the DQ coordinate system, is the inductance component of the D-axis in the DQ coordinate system.
[0012] Furthermore, the maximum negative torque , the calculation formula is as follows: (11); in, Represents the permanent magnet flux.
[0013] Furthermore, the angular position information detected by the position sensor is preprocessed, including filtering and denoising.
[0014] Furthermore, the storage uses a non-volatile memory, including an EEPROM and a Flash memory, for storing the position estimation value of the motor through data transmission.
[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a motor control method for reducing start-stop impact. Active short circuit control is used in the final stage of shutdown to completely stop the motor, which can avoid the problem of mechanical impact caused by unstable speed control due to poor speed calculation accuracy at low speed. In addition, active short circuit can generate relatively stable negative torque, which is beneficial to reduce mechanical impact.
[0016] 2. The present invention provides a motor control method for reducing start-stop impact. By using the position at the last shutdown during startup, the position error during startup is reduced, which is beneficial to improving the open-loop speed control accuracy during startup. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 is a flowchart of a shutdown process provided by an embodiment of the present invention; Figure 2 is a flowchart of the startup process provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of the shutdown principle provided by an embodiment of the present invention; Figure 4 is a schematic diagram of a shutdown result provided by an embodiment of the present invention; Figure 5 It is a schematic diagram of the startup principle provided by an embodiment of the present invention; Figure 6 is a schematic diagram of startup results provided by an embodiment of the present invention; Figure 7 is a schematic diagram of a shutdown process provided by an embodiment of the present invention; Figure 8 It is a schematic diagram of the startup process provided by an embodiment of the present invention. DETAILED DESCRIPTION
[0018] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention. Example
[0019] This embodiment introduces a motor control method for reducing start-stop impact, including: When the motor is in working state, obtaining the angular position information and the rotation speed information of the motor in real time; When the motor receives a stop command, if the stop command is a non-fault emergency stop command, the motor speed is reduced to a calibrated speed value according to the calibrated deceleration; Actively short-circuit the lower three bridges of the motor to generate maximum negative torque and accelerate shutdown; When the pre-calibrated duration is reached or the motor has completely stopped rotating, the active short-circuit control of the lower three bridges is terminated, and the angular position information of the motor at the last moment of the stop period is stored; When the motor is in a stopped state and receives a start command, the stored angle position information is sent to the motor open-loop start program, and the motor is started according to the sent angle position information.
[0020] like Figure 1-Figure 8 As shown, the motor control method for reducing start-stop impact provided in this embodiment specifically involves the following steps: Step 1: Assuming that the motor is in a high-speed working state, the position sensorless motor continuously updates the output angle position and the current motor speed according to the current motor operation information; when the motor receives a stop command, it first determines whether the stop command received by the motor is caused by a fault; if it is an emergency stop due to a fault, it will be quickly stopped through other procedures such as shutting down the pipe to avoid causing greater danger; if it is a normal command stop, the speed will decrease at a calibrated rate, so that the controlled motor speed will gradually decrease until it reaches the set calibrable speed value; when the motor speed reaches the calibrable speed value, the lower three bridge active short-circuit control is started, so that the three lower bridge arms of the motor are actively short-circuited to generate the maximum negative torque to accelerate the shutdown; when the pre-calibrated duration is reached or the motor has completely stopped rotating, the active short-circuit control is terminated, the motor is completely stopped, and the angle position information of the last stop period of the position sensorless motor is recorded, and the last updated high-precision position estimate is stored in the non-volatile memory. When the motor is started again, the position information is read from the memory and used as the initial position reference at startup, and the shutdown procedure is terminated. The present invention uses active short circuit control to completely stop the motor, which can avoid the problem of unstable speed control and mechanical impact caused by poor speed calculation accuracy at low speed.
[0021] Step 2: Assuming that the motor is in a stopped state, the motor receives a start command. First, determine whether the motor has an unresolved fault; if there is a fault, block the start command until the fault is resolved; if there is no fault, pre-process the last recorded angle position information, such as filtering and denoising, to exclude abnormal point data to improve data quality. The processed data is sent to the motor open-loop start program, and the motor is started according to the angle position and other information sent in, rather than starting the motor at zero position, to reduce the probability of mechanical collision and protect the safety of the equipment. The motor starts open-loop control until the closed-loop sensorless control speed switching point is met, and then the sensorless control is switched on. The output angle position and speed data are calculated according to the position sensorless control algorithm, and the motor operation information is updated in real time. This speed and position estimate will serve as an important basis for the control system to adjust the motor's operating state and achieve precise control to meet the realization of various working conditions.
[0022] Among them, the three-phase active short-circuit principle is as follows: In the mathematical model under the synchronous rotating coordinate system DQ, the stator voltage equation can be expressed as: (1); The stator flux equation is: (2); Combining equations (1) and (2) we can get the stator voltage equation: (3); in: , They are the DQ axis components of the stator voltage respectively; , are the DQ axis components of the stator current respectively; R is the stator resistance; is the DQ axis component of the stator flux; is the electrical angular velocity; , They are the DQ axis inductance components respectively; Represents the permanent magnet flux.
[0023] At this time, the electromagnetic torque equation can be written as: (4); When the three-phase short circuit is in steady state, , substituting into (3), we have: (5); Can be reversed and : (6); Substituting equation (6) into equation (4) yields the steady-state electromagnetic torque equation for three-phase short circuit: (7); again , is the motor electrical angular velocity, is the number of motor pole pairs, is the motor mechanical angular velocity; but: (8); In order to provide braking force with maximum torque in the case of three-phase short circuit and help the motor stop faster, the derivative of equation (8) is obtained at the speed point where the maximum torque output occurs: (9); have to: (10); Substituting (10) into (8), we can find Maximum torque braking force at , (11); From formula (11), we can see that The maximum braking output torque can be obtained by actively short-circuiting the three phases. In practical applications, the speed tangent point of the three active short circuits can be calculated according to the actual parameters of the motor, and the algorithm can be designed based on this.
[0024] The motor control method for reducing start-stop impact provided in this embodiment uses active short circuit control to completely stop the motor in the final stage of shutdown to avoid the problem of mechanical impact caused by unstable speed control due to poor speed calculation accuracy at low speed, and active short circuit can generate relatively stable negative torque, which is conducive to reducing mechanical impact. When starting, by using the position at the last shutdown, the position error at startup is reduced, which is conducive to improving the open-loop speed control accuracy at startup.
[0025] This embodiment aims to solve the problem that there is still a certain probability of abnormal noise when starting with a small current. For the control occasion without position sensor, the technical solution of the present invention sets the motor position at startup to the estimated position at the last shutdown, instead of resetting the initial position to 0 every time it starts, which can further reduce the probability of mechanical impact abnormal noise at startup. When the controller is powered off, the position after shutdown is stored in the non-volatile memory for use at the first startup after the next power-on.
[0026] Embodiment 2: This embodiment provides a motor control method for reducing start-stop impact according to Embodiment 1, wherein non-volatile memory, including EEPROM and Flash memory, is used for storage to store the motor position estimation value through data transmission.
[0027] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A motor control method for reducing start-stop impact, characterized in that: include: When the motor is in working state, obtaining the angular position information and the rotation speed information of the motor in real time; When the motor receives a stop command, if the stop command is a non-fault emergency stop command, the motor speed is reduced to a calibrated speed value according to the calibrated deceleration; Actively short-circuit the lower three bridges of the motor to generate maximum negative torque and accelerate shutdown; When the pre-calibrated duration is reached or the motor has completely stopped rotating, the active short-circuit control of the lower three bridges is terminated, and the angular position information of the motor at the last moment of the stop period is stored; When the motor is in a stopped state and receives a start command, the stored angle position information is sent to the motor open-loop start program, and the motor is started according to the sent angle position information.
2. The motor control method for reducing start-stop impact according to claim 1, characterized in that: If the stop command is a fault emergency stop command, the rapid stop procedure is executed.
3. The motor control method for reducing start-stop impact according to claim 1, characterized in that: When the motor is in a stopped state and receives a start command, it is first determined whether the motor has an unresolved fault; If there are unresolved faults, the start command is blocked.
4. The motor control method for reducing start-stop impact according to claim 1, characterized in that: The motor starts open-loop control until the closed-loop sensorless control speed switching point is met, and then switches into sensorless control. The motor's angular position information and speed information are detected and updated based on the position sensor.
5. The motor control method for reducing start-stop impact according to claim 1, characterized in that: The calibratable speed value , the calculation formula is as follows: （10）； Where R is the resistance of the stator in the motor; is the number of motor pole pairs, is the inductance component of the Q axis in the DQ coordinate system, is the inductance component of the D-axis in the DQ coordinate system.
6. The motor control method for reducing start-stop impact according to claim 5, characterized in that: The maximum negative torque , the calculation formula is as follows: （11）； in, Represents the permanent magnet flux.
7. The motor control method for reducing start-stop impact according to claim 4, characterized in that: The angle position information detected by the position sensor is preprocessed, including filtering and denoising.
8. The motor control method for reducing start-stop impact according to claim 1, characterized in that: The storage adopts non-volatile memory, including EEPROM and Flash memory, which is used to store the position estimation value of the motor through data transmission.