A Hall position sensor calibration method based on a sensorless motor control algorithm

Abstract

The present invention provides a calibration method for a Hall position sensor based on a sensorless motor control algorithm, belonging to the field of motor control. It solves the problem of accurately positioning the Hall sensor. The calibration method for the Hall position sensor based on the sensorless motor control algorithm includes a motor and a motor controller for detecting the phase current. A Hall position sensor is installed on the motor. The power line and communication line of the motor controller and the motor are connected to form a motor system. This method enables the motor to run to a stable set speed through an open-loop control algorithm and a closed-loop control algorithm, then records the estimated position of the Hall position signal switching point, continuously records the position data multiple times, and finally obtains the average position value of the switching point, which is the absolute position of the calibrated Hall switching point. The present invention has the advantages of not relying on complex test conditions and test environments and being able to calibrate the Hall position sensor portably, quickly, and accurately.

Description

Technical Field

[0001] The present invention belongs to the field of motor control and relates to a calibration method for Hall position sensors based on sensorless motor control algorithms. Background Art

[0002] In recent years, with the popularization and application of power electronics technology, computer technology, new motor control theory, and frequency conversion technology, and the rapid development of power electronic power devices, microprocessor chips, and rare earth permanent magnet materials, AC permanent magnet motors have entered a new stage of rapid development. Due to a series of advantages such as small volume, light weight, high efficiency, and energy saving, AC permanent magnet motors have attracted more and more attention, been widely promoted and applied, and the variable frequency speed regulation of small and medium power asynchronous motors is gradually being replaced by AC permanent magnet motor speed regulation systems. Currently, the AC permanent magnet motors commonly used in industry are divided into permanent magnet synchronous motors and brushless DC motors (BLDC). The mainstream control methods for these two types of motors are vector control (FOC sine wave control) and six-step commutation control (trapezoidal wave control), respectively. Matched with the control methods, the sensors installed on permanent magnet synchronous motors are mainly resolvers and encoders, and Hall sensors are installed on BLDC motors. Resolvers and encoders have high position acquisition accuracy and are suitable for precise control, but the control methods are complex and the cost is high; Hall sensors are inexpensive and the control is simple, but the position acquisition accuracy is very poor and they cannot be used for precise control. In engineering applications, for resolver or encoder sensors, they can be used as long as their zero positions are calibrated. However, for Hall sensors, in order to obtain better control effects, each Hall position needs to be calibrated. Especially in some cross-boundary control engineering applications, under the condition of using inexpensive Hall sensors, in order to achieve the control objectives of stable operation, low noise, and high efficiency, FOC vector control needs to be adopted, which requires more precise calibration of the Hall sensor position. Summary of the Invention

[0003] The object of the present invention is to provide a calibration method for Hall position sensors based on sensorless motor control algorithms in view of the above problems existing in the prior art. The absolute position of the rotor is estimated by using a sensorless sliding mode control algorithm, and this absolute position is borrowed to calibrate the Hall position sensor, so as to associate the Hall sensor signal with the absolute position and improve the accuracy of the angle of the automatic calibration method.

[0004] The purpose of the present invention can be achieved through the following technical solutions: a Hall position sensor calibration method based on a sensorless motor control algorithm, comprising a motor and a motor controller with a phase current detection function, a Hall position sensor is installed on the motor, and the motor controller and the power line and communication line of the motor are connected to form a motor system, characterized in that the method uses an open-loop control algorithm and a closed-loop control algorithm to make the motor run to a stable set speed, and then records the estimated position of the Hall position signal switching point, continuously records multiple position data, and finally obtains the average position value of the switching point, which is the absolute position of the Hall switching point we have calibrated. The entire calibration process can be represented by a flowchart. Around the entire process, from the start of the motor to the motor coming to a standstill, we subdivide it into the following steps:

[0005] S1: Connect the motor controller and the motor, connect the high and low voltage power supply to the motor controller, prepare the host computer or touch screen for control, and connect the communication line;

[0006] S2: Control the motor system through the host computer or touch screen. At first, the electronic rotor is locked and maintained, and then the motor system starts to run in open loop at low speed, and the speed gradually increases. The control angle at this stage is the open loop angle;

[0007] S3: The motor speed increases to a certain switching speed, and the open-loop control algorithm switches to the closed-loop control algorithm. The control angle at this stage is the angle estimated by the sensorless algorithm.

[0008] S4: Continue to increase the speed to a certain speed, run stably, and then start the Hall sensor calibration. Before starting the calibration, the motor controller will verify the correctness of the motor's Hall signal. If the Hall signal is missing or wrong, the motor controller will detect it and report it to the host computer or touch screen to warn or stop the calibration process. If the Hall signal is correct, the calibration work officially begins, and the angle used for calibration is the sliding mode estimation angle;

[0009] S5: After the calibration starts, the absolute angle value of each Hall signal switching point is collected and recorded, and dozens of sets of data are recorded continuously;

[0010] S6: After the data collection and recording is completed, the recorded data is divided by the number of records to obtain the average absolute position of each switching point;

[0011] S7: The angle of each sector can be calculated by averaging the switching positions. So far, the calibration of the Hall sensor is completed.

[0012] S8: After the entire calibration work is completed, the motor speed is gradually reduced to zero.

[0013] Compared with the prior art, the Hall position sensor calibration method based on the sensorless motor control algorithm only requires a motor and a motor controller, does not rely on complex test conditions and test environments, can calibrate the Hall position sensor portably, quickly and accurately, and can also judge the quality of the Hall sensor. It has the following advantages:

[0014] 1. Improve production efficiency and speed up the test speed. This calibration method is simple and fast, the test conditions are simple and easy to implement, there are no high requirements for the test environment, no additional test benches and test instruments are needed, and only a motor, a controller and a power supply are required to complete the entire calibration process. Therefore, during the production of motors, the test calibration time is reduced, and the labor productivity is greatly improved;

[0015] 2. This method has a certain load compatibility ability, does not require the motor system to be disassembled from the equipment, and supports calibration with load. During calibration, there is no need to change the hardware connection state, and only by sending a calibration command to the motor system, the motor controller can drive the motor to execute the calibration process. The entire process does not require manual intervention, and the calibrated results will be automatically stored in the memory. Therefore, this calibration method brings convenience to manufacturers or customers;

[0016] 3. The rotor angle adopted by this method is not the open-loop given angle, but the angle estimated by the positionless control algorithm when the speed is stable. Because there are inherent deviations between the open-loop angle and the actual rotor angle under some test conditions and they cannot be eliminated, using the open-loop angle to calibrate the Hall position angle will also have this angle deviation. If the estimated absolute position angle is used to calibrate the Hall sensor, a high accuracy can be achieved. This accuracy is related to the accuracy of the positionless control, and we can improve this accuracy by optimizing the algorithm parameters;

[0017] 4. This method can intelligently identify the correctness of the Hall signal. If there is a Hall signal phase loss or error, this method can immediately identify it and give an alarm or stop the calibration process;

[0018] 5. The angle calibrated by this automatic calibration method can be retrieved or modified by command, which brings convenience to large-scale motor production and testing work as well as after-sales service. Brief Description of the Drawings

[0019] Figure 1 It is the structural block diagram of the motor system.

[0020] Figure 2 It is the flow chart of the calibration process of the motor Hall position sensor.

[0021] Figure 3 It is the coordinate diagram of the corresponding relationship between the calibration process of the motor Hall position sensor and the motor speed.

[0022] Figure 4 It is a block diagram of a sensorless control algorithm for an AC permanent magnet motor with a Hall position sensor calibration function.

[0023] Figure 5 It is a comparison chart of the sensorless control estimated angle and the output signal of the Hall position sensor.

[0024] Figure 6 It is a flowchart of the Hall signal switching angle recording and calculation in the calibration process. Specific implementation manner

[0025] The following are specific embodiments of the present invention and, in combination with the accompanying drawings, the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

[0026] As Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, the Hall position sensor calibration method based on the sensorless motor control algorithm includes a motor and a motor controller with phase current detection to implement the sensorless control algorithm. A Hall position sensor is installed on the motor, and the installation method is 120° installation method or 60° installation method. The power line and communication line of the motor controller and the motor are connected to form a motor system. This method makes the motor run to a stable set speed through an open-loop control algorithm and a closed-loop control algorithm, and then records the estimated position of the Hall position signal switching point. See Appendix Figure 5 , continuously record the position data multiple times, and finally obtain the average position value of the switching point, which is the absolute position of the calibrated Hall switching point. The entire calibration process can be represented by the flowchart in Appendix Figure 2 . Around the entire process, from the motor starting to the motor stopping, we divide it into the following steps. The key time points involved in each step can be referred to Appendix Figure 3 for understanding:

[0027] S1: Connect the motor controller and the motor, turn on the high and low voltage power supplies for the motor controller, and at the same time prepare the control upper computer or touch screen, and connect the communication line;

[0028] S2: Control the operation of the motor system through the upper computer or touch screen. At first, the electronic rotor is locked and held. See Appendix Figure 3 , and then the motor system starts to run in open loop at a low speed range. See Appendix Figure 3 , and the speed gradually increases. The control angle in this stage is the open-loop angle;

[0029] S3: The motor running speed increases to a certain switching speed. See AppendixFigure 3 , the open-loop control algorithm switches to the closed-loop control algorithm. The control angle in this stage is the angle estimated by the sensorless algorithm;

[0030] S4: Continue to increase the speed to a certain speed, stable operation see attached Figure 3 , and then start the Hall sensor calibration. Before starting the calibration, the motor controller will verify the correctness of the motor's Hall signal. If the Hall signal is missing or wrong, the motor controller will detect it and report it to the host computer or touch screen to warn or stop the calibration process. If the Hall signal is correct, the calibration work officially begins. See attached Figure 3 , the calibration angle is the sliding mode estimation angle;

[0031] S5: After the calibration starts, the absolute angle value of each Hall signal switching point is collected and recorded, and dozens of sets of data are recorded continuously;

[0032] S6: After the data collection and recording is completed, the recorded data is divided by the number of records to obtain the average absolute position of each switching point;

[0033] S7: The angle of each sector can be calculated by averaging the switching position. So far, the Hall sensor calibration is completed. See attached Figure 3 ;

[0034] S8: After the entire calibration work is completed, gradually reduce the motor speed to zero (see attached) Figure 3 .

[0035] Technical improvements

[0036] The present invention provides a Hall position sensor calibration method based on a sensorless motor control algorithm. This method can calibrate the Hall absolute position conveniently, quickly and accurately without the need for a test bench or test instrument, only requiring a motor and a controller, and even when a certain load is connected. Compared with the above method, the following improvements and optimizations are made:

[0037] First, in view of the deficiency of bench calibration method that is heavily dependent on test environment and test equipment, the method adopted by this patent is that the motor system automatically runs and executes the calibration process, and no additional dragging equipment is required. All measurement quantities and calculation data are completed inside the motor system, and there is no need to obtain measurement data from the outside world.

[0038] Second, for the existing automatic calibration method that uses the open-loop angle to calibrate the Hall position angle, there is a certain angle deviation, and there is a problem that the accurate absolute position cannot be obtained. The calibration angle adopted in this patent is the closed-loop angle estimated by the sensorless control algorithm. This method has several characteristics: 1. The accuracy of the angle calibrated according to this method is related to the sensorless control algorithm. The more accurate the angle estimated by the sensorless control, the more accurate the Hall angle calibrated by this angle. 2. The sensorless control algorithm angle involved in this patent is calculated based on the back electromotive force of the motor. Therefore, in order to obtain a reliable and stable estimated angle, the motor needs to run at a suitable speed point in the speed closed-loop mode, and the sensorless control algorithm needs to adopt suitable motor parameters. 3. The open-loop operation mode and the open-loop angle used in this patent are only used to run the motor to the open-closed loop switching speed and do not participate in the Hall sensor angle calibration;

[0039] Third, the signals of some Hall sensors do not conform to common sense and cannot be calibrated. This patent proposes to diagnose such problems early and report them to the upper computer or the touch screen. In case of serious situations, the calibration process should be stopped.

[0040] Working principle

[0041] Description of the whole process of the solution: After the Hall position sensor of the motor is connected to the motor controller, as the motor rotor rotates, the Hall position signal will change accordingly. If the angle values corresponding to the Hall signal change moment can be measured or estimated and these angle values are associated with the Hall change signal, then the motor rotor position can be directly calculated based on the Hall signal, and then the motor operation can be controlled. The whole technical solution can be divided into the following stages when detailed:

[0042] 1. Calibration preparation stage

[0043] In the calibration preparation stage, the hardware preparation work and the software preparation work need to be completed. The hardware preparation work includes the construction of the motor system, the connection of the power line and communication line between the motor controller and the motor, the fixation of the motor system, the connection of the power supply, the arrangement of the upper computer, the connection of the communication line, etc. The software preparation work includes the writing and debugging of the calibration function software, the debugging of the upper computer control software, the measurement and tuning of the sensorless algorithm parameters;

[0044] 2. Obtaining a stable calibration speed stage

[0045] To reach a stable calibration speed, it is necessary to control the motor under test to rotate. Here, the angle open-loop control method is adopted to start the motor. At this time, both the motor angle and speed values are calculated and given by software. After the speed rises, it is switched to the speed closed-loop control method. At this time, both the motor angle and speed values are estimated by the sensorless control algorithm. Before the motor starts with open-loop control, the motor rotor needs to be locked at a fixed angle using the stator magnetic field. After open-loop operation, the open-loop angle value in the software increases with a stable acceleration in each switching period. The motor rotor follows the stator magnetic flux of the motor to make a rotational motion, and the rotational speed becomes faster and faster. During the open-loop operation process, the angle estimated by the sensorless control algorithm becomes more and more accurate as the speed increases. When the speed reaches the switching speed, the open-loop control algorithm switches to the closed-loop control algorithm. At this time, the motor angle and speed values in the control algorithm start to use the angle and speed estimated by the sensorless algorithm. The speed sent by the host computer or the preset calibration speed inside the software becomes the control target. The motor accelerates towards the target speed, and the speed becomes faster and faster until it reaches the set speed and no longer rises, and runs stably. At this time, the stable speed is prepared for the calibration of the next Hall sensor. The more stable the speed, the more equal the sectors passed in each switching period, and the more stable the estimated angle corresponding to each switching point;

[0046] 3. Angle calibration stage

[0047] This stage can refer to the appendix Figure 6 . After the motor speed stabilizes at the calibration speed, the program starts to execute the Hall sensor signal diagnosis, which is a necessary condition for entering the angle calibration stage. When the Hall sensor is diagnosed as normal, the Hall angle calibration starts next. If a sensor fault is diagnosed, the Hall sensor calibration is stopped, and the diagnosed fault is reported to the host computer or the touch screen. The Hall sensor calibration uses the angle value calculated by the sensorless control algorithm. Here, in order to obtain a more accurate result, the method of accumulating the sampled angles multiple times and taking the average is adopted. After obtaining the angle values of the Hall signal switching points, the angle values of the six sectors can be obtained based on these values. Here, attention needs to be paid to the calculation of the sectors spanning two electrical angle periods.

[0048] The specific embodiments described in this article are only examples to illustrate the spirit of the present invention. Those skilled in the art of the present invention can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A calibration method for Hall position sensors based on sensorless motor control algorithms, including a motor and a motor controller for detecting phase current. A Hall position sensor is installed on the motor. The power line and communication line of the motor controller and the motor are connected to form a motor system, characterized in that, This method uses open-loop control algorithms and closed-loop control algorithms to make the motor run to a stable set speed, then records the estimated position of the Hall position signal switching point, continuously records multiple position data, and finally obtains the average position value of the switching point. This value is the absolute position of the Hall switching point that we have calibrated. Around the entire process, from the motor starting to the motor stopping, we will subdivide it into the following steps: S1: Connect the motor controller and the motor, connect the high and low voltage power supply to the motor controller, prepare the host computer or touch screen for control, and connect the communication line; S2: The motor system is controlled by the host computer or touch screen. At first, the electronic rotor is locked and maintained, and then the motor system starts to run in an open loop at a low speed. The speed gradually increases. The control angle at this stage is the open loop angle. S3: The motor speed increases to a certain switching speed, and the open-loop control algorithm switches to the closed-loop control algorithm. The control angle at this stage is the angle estimated by the sensorless algorithm. S4: Continue to increase the speed to a certain speed, run stably, and then start the Hall sensor calibration. Before starting the calibration, the motor controller will identify the correctness of the Hall signal of the motor. If the Hall signal is missing or wrong, the motor controller will detect it and report it to the host computer or touch screen to warn or stop the calibration process. If the Hall signal is correct, the calibration work officially starts, and the angle used for calibration is the sliding mode estimation angle; S5: After the calibration starts, the absolute angle value of each Hall signal switching point is collected and recorded, and dozens of sets of data are recorded continuously; S6: After the data collection and recording is completed, the recorded data is divided by the number of records to obtain the average absolute position of each switching point; S7: The angle of each sector can be calculated by averaging the switching positions. So far, the calibration of the Hall sensor is completed. S8: After the entire calibration work is completed, the motor speed is gradually reduced to zero.

Images