A method for estimating position of permanent magnet synchronous motor based on Hall sensor

Abstract

The present invention discloses a method for estimating the position of a permanent magnet synchronous motor based on a Hall sensor. The method comprises: obtaining a back electromotive force term according to the three-phase current value of the permanent magnet synchronous motor; obtaining a rotor speed function value by using an inner product operation method according to the feedback estimation angle and the back electromotive force term, and obtaining the rotor speed by a table lookup method; inputting the rotor speed and the feedback speed into a PI controller, using the Hall average speed as a feedforward input, outputting the electrical angular velocity of the permanent magnet synchronous motor rotor, converting it into a mechanical angular velocity, and obtaining the position of the permanent magnet synchronous motor rotor by discrete integration, and finally realizing the position estimation of the permanent magnet synchronous motor. The present invention uses a Hall sensor to obtain the rotor speed and position information of the permanent magnet synchronous motor with high resolution and accuracy, and at the same time makes up for the angle estimation error caused by the update lag of the Hall sensor. Using the Hall signal of the Hall sensor as the feedforward input of the PI controller can eliminate noise interference and improve the steady-state and dynamic performance of the motor operation.

Description

Technical Field

[0001] The invention relates to a method for estimating the position of a permanent magnet synchronous motor, and in particular to a method for estimating the position of a permanent magnet synchronous motor based on a Hall sensor. Background Art

[0002] Permanent magnet synchronous motors have the advantages of high efficiency and high power density, and are widely used in the industrial field. Permanent magnet synchronous motors using high-precision position sensors can achieve good control effects, but the reliability and stability of high-precision sensors in harsh environments will be affected; sensorless control technology using motors is limited in applications such as heavy-load starting. The motor control system using Hall sensors has good stability and long service life, but the low accuracy causes the traditional method to perform poorly in dynamic performance, and the control effect is poor in situations such as starting and load fluctuations, and there may even be risks such as loss of control. Summary of the invention

[0003] In order to solve the problems existing in the background technology, the present invention provides a permanent magnet synchronous motor position estimation method based on a Hall sensor, which can obtain the rotor position information of the permanent magnet synchronous motor with high resolution accuracy.

[0004] The technical solution adopted by the present invention is:

[0005] The method for estimating the position of a permanent magnet synchronous motor of the present invention comprises the following steps:

[0006] Step 1: Collect the three-phase current values ​​of the permanent magnet synchronous motor installed with the Hall sensor at the current moment and the previous moment, and obtain the back electromotive force term of the permanent magnet synchronous motor at the previous moment according to the three-phase current values ​​of the permanent magnet synchronous motor at the current moment and the previous moment; the back electromotive force term contains the rotor speed position information; the Hall sensor is installed at the non-driving end of the permanent magnet synchronous motor, and the motor rotor position is detected by the small magnet corresponding to the permanent magnet installed on the detection shaft of the permanent magnet synchronous motor.

[0007] The permanent magnet synchronous motor specifically adopts a surface-mounted permanent magnet synchronous motor. The Hall sensor is a three-phase Hall sensor based on the Hall effect, which can output a three-phase Hall signal according to the corresponding magnetic pole position.

[0008] Step 2: Obtain the feedback estimated angle of the permanent magnet synchronous motor rotor at the current moment, and use the inner product operation method to obtain the rotor speed function value of the permanent magnet synchronous motor according to the feedback estimated angle of the permanent magnet synchronous motor rotor at the current moment and the back electromotive force term of the permanent magnet synchronous motor at the previous moment, and obtain the rotor speed function value of the permanent magnet synchronous motor at the previous moment by using the table lookup method.

[0009] Step 3: When the permanent magnet synchronous motor is running, the Hall sensor outputs a Hall signal, and the Hall average speed is obtained according to the Hall signal; the feedback speed of the permanent magnet synchronous motor rotor at the previous moment is obtained, and the speed and feedback speed of the permanent magnet synchronous motor rotor at the previous moment are input into the PI controller, and the Hall average speed is used as the feedforward input of the PI controller. The PI controller outputs the electrical angular velocity of the permanent magnet synchronous motor rotor, and the electrical angular velocity of the permanent magnet synchronous motor rotor is discretely integrated to obtain the position of the permanent magnet synchronous motor rotor, and finally the position estimation of the permanent magnet synchronous motor is realized. When the control error of the PI controller converges to zero, the high-precision electrical angular velocity of the permanent magnet synchronous motor rotor can be obtained; the PI controller also outputs the feedback speed of the permanent magnet synchronous motor rotor at the current moment to continue the position estimation of the permanent magnet synchronous motor at the next moment.

[0010] The Hall signal can be used to correct the position of the permanent magnet synchronous motor rotor every 60° electrical angle, and the rotor position is updated when the Hall sector is switched to eliminate the accumulated error.

[0011] In the step 1, the back electromotive force term of the permanent magnet synchronous motor is obtained according to the three-phase current values ​​of the permanent magnet synchronous motor at the current moment and the previous moment. Specifically, the three-phase current of the permanent magnet synchronous motor at the current moment and the previous moment is first subjected to coordinate transformation to obtain the α-phase static current and the β-phase static current in the αβ coordinate system, that is, the α-phase static current value and the β-phase static current value are obtained according to the three-phase current values ​​of the permanent magnet synchronous motor at the current moment and the previous moment, and then the back electromotive force term of the permanent magnet synchronous motor is obtained according to the α-phase static current value and the β-phase static current value of the permanent magnet synchronous motor at the current moment and the previous moment, as follows:

[0012]

[0013] Where D[k-1] represents the back electromotive force term of the permanent magnet synchronous motor at the previous k-1 time; i α (k) and i α (k-1) represents the α-phase static current value of the permanent magnet synchronous motor at the current k moment and the previous k-1 moment, i β (k) and i β (k-1) represents the β-phase static current value of the permanent magnet synchronous motor at the current k moment and the previous k-1 moment respectively; u a (k-1) and u β (k-1) respectively represent the α-phase voltage value and β-phase voltage value of the permanent magnet synchronous motor at the k-1 moment before; the voltage value of the permanent magnet synchronous motor at the k-1 moment before is directly given by the vector control target voltage value, that is, the preset value, without sampling, and the voltage value of the permanent magnet synchronous motor at the k-1 moment before is obtained by coordinate transformation of the α-phase voltage value and the β-phase voltage value in the αβ coordinate system. A and B are the first constant term and the second constant term of the back electromotive force term of the permanent magnet synchronous motor, respectively.

[0014] The first constant term and the second constant term of the back electromotive force term of the permanent magnet synchronous motor are specifically as follows:

[0015]

[0016] Among them, T s Represents the current loop control period of the permanent magnet synchronous motor; R s Indicates the stator resistance of the permanent magnet synchronous motor; L s Represents the motor AC-axis and DC-axis inductance of the permanent magnet synchronous motor.

[0017] In the step 2, according to the feedback estimated angle of the permanent magnet synchronous motor rotor at the current moment and the back electromotive force term of the permanent magnet synchronous motor at the previous moment, the inner product calculation method is used to obtain the rotor speed function value f(ω e ), and obtain the speed of the permanent magnet synchronous motor rotor at the previous moment by table lookup method, as follows:

[0018]

[0019]

[0020] Among them, ψ f represents the permanent magnet flux of the permanent magnet synchronous motor; ω e [k-1] represents the speed of the permanent magnet synchronous motor rotor at the previous k-1 moments; θ e [k] and θ e [k-1] represents the estimated angles of the permanent magnet synchronous motor rotor at the current k moment and the previous k-1 moment, that is, it represents the feedback estimated angles of the permanent magnet synchronous motor rotor at the next moment and the current k moment, respectively.

[0021] In step 3, the average Hall speed is obtained according to the Hall signal, as follows:

[0022]

[0023] Among them, ω ehall It represents the average speed of the Hall sensor, and Δt represents the duration of a Hall sector on the Hall sensor.

[0024] The beneficial effects of the present invention are:

[0025] The present invention uses a Hall sensor to obtain high-resolution precision information about the rotor speed and rotor position of a permanent magnet synchronous motor, and can achieve corrected estimation of the position of the permanent magnet synchronous motor. The method of the present invention can make up for the angle estimation error caused by the Hall sensor update lag at a low speed stage, and the Hall signal is accurately estimated at a medium and high speed stage. Using it as a feedforward input of a PI controller can eliminate noise interference and achieve good steady-state and dynamic performance of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a control block diagram of a permanent magnet synchronous motor system according to an embodiment of the present invention.

[0027] Figure 2 This is a block diagram of the permanent magnet synchronous motor position estimation method of the present invention.

[0028] Figure 3 The figure is a waveform diagram of the rotation speed, rotor position and position error of the permanent magnet synchronous motor during the simulation startup process of the present invention.

[0029] Figure 4 The figure is a waveform diagram of the rotation speed, rotor position, position error and dq axis current of the permanent magnet synchronous motor during load fluctuation of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 2 As shown, the permanent magnet synchronous motor position estimation method of the present invention comprises the following steps:

[0032] Step 1: Collect the three-phase current values ​​of the permanent magnet synchronous motor installed with the Hall sensor at the current moment and the previous moment, and obtain the back electromotive force term of the permanent magnet synchronous motor at the previous moment according to the three-phase current values ​​of the permanent magnet synchronous motor at the current moment and the previous moment; the back electromotive force term contains the rotor speed position information; the Hall sensor is installed at the non-driving end of the permanent magnet synchronous motor, and the motor rotor position is detected by the small magnet corresponding to the permanent magnet installed on the detection shaft of the permanent magnet synchronous motor.

[0033] The permanent magnet synchronous motor specifically adopts a surface-mounted permanent magnet synchronous motor. The Hall sensor is a three-phase Hall sensor based on the Hall effect, which can output a three-phase Hall signal according to the corresponding magnetic pole position.

[0034] In step 1, the back electromotive force term of the permanent magnet synchronous motor is obtained according to the three-phase current values ​​of the permanent magnet synchronous motor at the current moment and the previous moment. Specifically, the three-phase current of the permanent magnet synchronous motor at the current moment and the previous moment is firstly transformed by coordinate transformation to obtain the α-phase static current and the β-phase static current in the αβ coordinate system, that is, the α-phase static current value and the β-phase static current value are obtained according to the three-phase current values ​​of the permanent magnet synchronous motor at the current moment and the previous moment, and then the back electromotive force term of the permanent magnet synchronous motor is obtained according to the α-phase static current value and the β-phase static current value of the permanent magnet synchronous motor at the current moment and the previous moment, as follows:

[0035]

[0036] Where D[k-1] represents the back electromotive force term of the permanent magnet synchronous motor at the previous k-1 time; i α (k) and i α (k-1) represents the α-phase static current value of the permanent magnet synchronous motor at the current k moment and the previous k-1 moment, i β (k) and i β (k-1) represents the β-phase static current value of the permanent magnet synchronous motor at the current k moment and the previous k-1 moment respectively; u α (k-1) and u β (k-1) respectively represent the α-phase voltage value and β-phase voltage value of the permanent magnet synchronous motor at the k-1 moment before; the voltage value of the permanent magnet synchronous motor at the k-1 moment before is directly given by the vector control target voltage value, that is, the preset value, without sampling, and the voltage value of the permanent magnet synchronous motor at the k-1 moment before is obtained by coordinate transformation of the α-phase voltage value and the β-phase voltage value in the αβ coordinate system. A and B are the first constant term and the second constant term of the back electromotive force term of the permanent magnet synchronous motor, respectively.

[0037] The first constant term and the second constant term of the back electromotive force term of the permanent magnet synchronous motor are as follows:

[0038]

[0039] Among them, T s Represents the current loop control period of the permanent magnet synchronous motor; R s Indicates the stator resistance of the permanent magnet synchronous motor; L s Represents the motor DC-axis inductance of the permanent magnet synchronous motor.

[0040] Step 2: Obtain the feedback estimated angle of the permanent magnet synchronous motor rotor at the current moment, and use the inner product operation method to obtain the rotor speed function value of the permanent magnet synchronous motor according to the feedback estimated angle of the permanent magnet synchronous motor rotor at the current moment and the back electromotive force term of the permanent magnet synchronous motor at the previous moment, and obtain the rotor speed function value of the permanent magnet synchronous motor at the previous moment by using the table lookup method.

[0041] In step 2, according to the feedback estimated angle of the permanent magnet synchronous motor rotor at the current moment and the back electromotive force term of the permanent magnet synchronous motor at the previous moment, the inner product calculation method is used to obtain the rotor speed function value f(ω e ), and obtain the speed of the permanent magnet synchronous motor rotor at the previous moment by table lookup method, as follows:

[0042]

[0043]

[0044] Among them, ψ f represents the permanent magnet flux of the permanent magnet synchronous motor; ω e [k-1] represents the speed of the permanent magnet synchronous motor rotor at the previous k-1 moments; θ e [k] and θ e [k-1] represents the estimated angles of the permanent magnet synchronous motor rotor at the current k moment and the previous k-1 moment, that is, it represents the feedback estimated angles of the permanent magnet synchronous motor rotor at the next moment and the current k moment, respectively.

[0045] Step 3: When the permanent magnet synchronous motor is running, the Hall sensor outputs a Hall signal, and the Hall average speed is obtained according to the Hall signal; the feedback speed ω of the permanent magnet synchronous motor rotor at the previous moment is obtained e '[k-1], the speed and feedback speed of the permanent magnet synchronous motor rotor at the previous moment are input into the PI controller, and the average Hall speed is used as the feedforward input of the PI controller. The PI controller outputs the electrical angular velocity of the permanent magnet synchronous motor rotor, and the electrical angular velocity of the permanent magnet synchronous motor rotor is discretely integrated to obtain the position of the permanent magnet synchronous motor rotor, and finally the position estimation of the permanent magnet synchronous motor is realized. When the control error of the PI controller converges to zero, the high-precision electrical angular velocity of the permanent magnet synchronous motor rotor can be obtained; the PI controller also outputs the feedback speed of the permanent magnet synchronous motor rotor at the current moment to continue the position estimation of the permanent magnet synchronous motor at the next moment.

[0046] In step 3, the average Hall speed is obtained according to the Hall signal, as follows:

[0047]

[0048] Among them, ω ehall It represents the average speed of the Hall sensor, and Δt represents the duration of a Hall sector on the Hall sensor.

[0049] Hall signal can be used every 60° electrical angle abc Perform position correction on the permanent magnet synchronous motor rotor, update the rotor position when the Hall sectors switch, and eliminate the accumulated error.

[0050] like Figure 1 As shown, the present invention simulates a surface-mounted permanent magnet synchronous motor based on a Hall position sensor powered by a voltage source inverter after the motor position is estimated. The motor and inverter parameters are shown in Table 1 below:

[0051] Table 1 Permanent magnet synchronous motor and inverter parameters

[0052]

[0053]

[0054] The motor position estimation method of the present invention obtains the electrical angular velocity of the permanent magnet synchronous motor rotor and converts the electrical angular velocity of the permanent magnet synchronous motor rotor into a mechanical angular velocity, as follows:

[0055]

[0056] Among them, ω r represents the mechanical angular velocity of the permanent magnet synchronous motor rotor; p n Represents the number of motor pole pairs of the permanent magnet synchronous motor, which is 4 in the specific implementation; ω e It represents the electrical angular velocity of the permanent magnet synchronous motor rotor.

[0057] like Figure 1 In the motor system control process shown in the figure, i a and i b is the phase current sampled by the motor, ω r is the mechanical angular velocity, ω r * is the target control speed, and ω r After PI operation, the q-axis current given i is obtained q * , then the target current i of the stationary shaft system d * and i q * After PI calculation, the stationary shaft target voltage u is obtained. d * and u q * , among which the surface mounted permanent magnet synchronous motor i d * Usually 0 is given. Then the rotating shaft voltage u is obtained through coordinate transformation α * and u β * , input SVPWM to get the control pulse signal of the inverter to realize the operation of the permanent magnet synchronous motor, such as Figure 3 As shown in the figure, the speed, rotor position and position error waveform of the permanent magnet synchronous motor during the simulation startup process are shown in the figure. Figure 4As shown, the speed, rotor position, position error and dq-axis current waveform of the permanent magnet synchronous motor during load fluctuation. It can be seen that the permanent magnet synchronous motor has good steady-state and dynamic performance.

Claims

1. A method for estimating the position of a permanent magnet synchronous motor based on a Hall sensor, characterized in that: The steps include: Step 1: Collect the three-phase current values ​​of the permanent magnet synchronous motor equipped with the Hall sensor at the current moment and the previous moment, and obtain the back electromotive force term of the permanent magnet synchronous motor at the previous moment according to the three-phase current values ​​of the permanent magnet synchronous motor at the current moment and the previous moment; Step 2: Obtain the feedback estimated angle of the permanent magnet synchronous motor rotor at the current moment, and use the inner product calculation method to obtain the rotor speed function value of the permanent magnet synchronous motor according to the feedback estimated angle of the permanent magnet synchronous motor rotor at the current moment and the back electromotive force term of the permanent magnet synchronous motor at the previous moment, and obtain the rotor speed of the permanent magnet synchronous motor at the previous moment by using the table lookup method; Step 3: When the permanent magnet synchronous motor is running, the Hall sensor outputs a Hall signal, and the Hall average speed is obtained according to the Hall signal; the feedback speed of the permanent magnet synchronous motor rotor at the previous moment is obtained, the speed and feedback speed of the permanent magnet synchronous motor rotor at the previous moment are input into the PI controller, and the Hall average speed is used as the feedforward input of the PI controller, the PI controller outputs the electrical angular velocity of the permanent magnet synchronous motor rotor, and the electrical angular velocity of the permanent magnet synchronous motor rotor is discretely integrated to obtain the position of the permanent magnet synchronous motor rotor, and finally the position estimation of the permanent magnet synchronous motor is realized.

2. The method for estimating the position of a permanent magnet synchronous motor based on a Hall sensor according to claim 1, characterized in that: In the step 1, the back electromotive force term of the permanent magnet synchronous motor is obtained according to the three-phase current values ​​of the permanent magnet synchronous motor at the current moment and the previous moment. Specifically, the three-phase current of the permanent magnet synchronous motor at the current moment and the previous moment is first subjected to coordinate transformation to obtain the α-phase static current and the β-phase static current in the αβ coordinate system, that is, the α-phase static current value and the β-phase static current value are obtained according to the three-phase current values ​​of the permanent magnet synchronous motor at the current moment and the previous moment, and then the back electromotive force term of the permanent magnet synchronous motor is obtained according to the α-phase static current value and the β-phase static current value of the permanent magnet synchronous motor at the current moment and the previous moment, as follows: Where D[k-1] represents the back electromotive force term of the permanent magnet synchronous motor at the previous k-1 time; i α (k) and i α (k-1) represents the α-phase static current value of the permanent magnet synchronous motor at the current k moment and the previous k-1 moment, i β (k) and i β (k-1) represents the β-phase static current value of the permanent magnet synchronous motor at the current k moment and the previous k-1 moment respectively; u α (k-1) and u β (k-1) respectively represent the α-phase voltage value and the β-phase voltage value of the permanent magnet synchronous motor at the previous k-1 moments; A and B respectively represent the first constant term and the second constant term of the back electromotive force term of the permanent magnet synchronous motor.

3. The method for estimating the position of a permanent magnet synchronous motor based on a Hall sensor according to claim 2, characterized in that: The first constant term and the second constant term of the back electromotive force term of the permanent magnet synchronous motor are specifically as follows: Among them, T s Represents the current loop control period of the permanent magnet synchronous motor; R s Indicates the stator resistance of the permanent magnet synchronous motor; L s Represents the motor DC-axis inductance of the permanent magnet synchronous motor.

4. The method for estimating the position of a permanent magnet synchronous motor based on a Hall sensor according to claim 3, characterized in that: In the step 2, according to the feedback estimated angle of the permanent magnet synchronous motor rotor at the current moment and the back electromotive force term of the permanent magnet synchronous motor at the previous moment, the inner product calculation method is used to obtain the rotor speed function value f(ω e ), and obtain the speed of the permanent magnet synchronous motor rotor at the previous moment by table lookup method, as follows: Among them, ψ f represents the permanent magnet flux of the permanent magnet synchronous motor; ω e [k-1] represents the speed of the permanent magnet synchronous motor rotor at the previous k-1 moments; θ e [k] and θ e [k-1] represents the estimated angles of the permanent magnet synchronous motor rotor at the current k moment and the previous k-1 moment, that is, it represents the feedback estimated angles of the permanent magnet synchronous motor rotor at the next moment and the current k moment, respectively.

5. The method for estimating the position of a permanent magnet synchronous motor based on a Hall sensor according to claim 1, characterized in that: In step 3, the average Hall speed is obtained according to the Hall signal, as follows: Among them, ω ehall It represents the average speed of the Hall sensor, and Δt represents the duration of a Hall sector on the Hall sensor.

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