阅读说明：本技术 一种表贴式永磁同步电机初始位置检测方法 (Surface-mounted permanent magnet synchronous motor initial position detection method ) 是由 陈峥 崔佳伦 吴一滔 于 2020-08-09 设计创作，主要内容包括：本发明属于电机控制技术领域,提供一种表贴式永磁同步电机初始位置检测方法,该方法包括：在电机直轴上注入一个高频脉振电压,采集电机三相电流I-a,I-b,I-c,经过坐标变换得到I-q；将I-q和高频正弦信号相调制,经过低通滤波器获得含有位置估计误差信息对信号积分后得到转子位置初次估计值采集霍尔位置传感器信号,以当前转子所处扇区作为初始角度的给定约束,判断实际直轴的正方向,若处于当前霍尔扇区,则否则本发明可检测表贴式永磁同步电机的转子初始位置,以当前霍尔扇区作为初始角度的给定约束,从而避免了磁极判断,减少运算量,可以解决电机起动阶段转子位置估算精度不高和运算效率低的问题,保证永磁同步电机的顺利起动。(The invention belongs to the technical field of motor control, and provides a surface-mounted permanent magnet synchronous motor initial position detection method, which comprises the following steps: injecting a high-frequency pulse vibration voltage on a straight shaft of the motor to collect three-phase current I of the motor a ,I b ,I c Is transformed into coordinates to obtain I q (ii) a Will I q Modulating with high-frequency sinusoidal signal, and obtaining information containing position estimation error by low-pass filter To pair Obtaining a primary estimated value of the position of the rotor after signal integration Collecting Hall position sensor signals, taking the sector where the current rotor is positioned as given constraint of an initial angle, judging the positive direction of the actual straight axis, and if the positive direction is not the actual straight axis In the current Hall sector, then Otherwise The invention can detect the initial position of the rotor of the surface-mounted permanent magnet synchronous motor, takes the current Hall sector as the given constraint of the initial angle, thereby avoiding magnetic pole judgment, reducing the calculation amount, solving the problems of low estimation precision and low calculation efficiency of the rotor position in the starting stage of the motor and ensuring the smooth starting of the permanent magnet synchronous motor.)

1. A surface-mounted permanent magnet synchronous motor initial position detection method is characterized by comprising the following steps:

(1) detecting the initial position of the rotor: the voltage U under the d-q axis is set by adopting a current open loop structure_d＝0，U_q0; injecting a high-frequency sinusoidal voltage signal U on a d axis by adopting a pulse vibration high-frequency injection method_incos(ω_ht) collecting the three-phase current I of the motor at the moment_a,I_b,I_cIs transformed into coordinates to obtain I_q(ii) a Will I_qModulating with high-frequency sinusoidal signal, and obtaining information containing position estimation error by low-pass filterTo pairThe signal integration obtains the initial position value of the rotorThe calculation method is that,

wherein k is_iTo integrate the gain, k_i＞0；

(2) Judging the positive direction of the straight axis: reading a signal of a three-phase Hall position sensor to obtain a Hall sector N where a current rotor is located;

(3) actual initial angle calculation: judging the positive direction of the actual direct axis of the motor according to the Hall sector where the current rotor is positioned, and using the Hall sector N where the current rotor is positioned as a constraint condition to carry out initial position value on the rotorJudging whether compensation is needed or not, and finally obtaining the initial position theta of the actual rotor_final。

2. The method as claimed in claim 1, wherein the step (1) includes error information of position estimationThe calculation method is that,

the LPF selects an IIR type low-pass filter with less calculation amount to filter high-frequency harmonic amount until the frequency is 200 Hz.

3. The method as claimed in claim 1, wherein the step (3) of determining whether compensation is required comprises determining an estimated initial position of the rotorWhether it is in the current Hall sector, if it is in the current Hall sector, thenIf not in the current Hall sectorInterior, thenThe formula is as follows,

Technical Field

The invention belongs to the technical field of motor control, and particularly relates to a surface-mounted permanent magnet synchronous motor initial position detection method.

Background

The permanent magnet synchronous motor has the advantages of high efficiency, high torque current ratio, high power density, reliability and the like, and is widely applied to the fields of aerospace, automobiles, industrial manufacturing and the like. High performance PMSM drive systems have widely adopted vector control and direct torque control strategies, both of which require a position sensor to provide speed and rotor position information. In the control of a permanent magnet synchronous motor with a sensor, a rotary transformer or a photoelectric encoder is often used for rotor position estimation, and the sensor can achieve good rotor position estimation accuracy, but is high in cost, large in size and incapable of being applied in some occasions. The Hall sensor has the advantages of low cost, small size and the like, can provide six accurate position information in one electrical cycle, and has been successfully applied to a permanent magnet synchronous motor system. However, the hall position sensor has the problems of inaccurate rotor position estimation and low precision due to the factors of discrete characteristics, electromagnetic interference, installation errors and the like.

At present, the position sensor-free control technology can obtain the position information of the motor rotor through a fundamental wave model or by injecting high-frequency information. The detection of the initial position of the rotor is the primary problem of realizing the operation of the permanent magnet synchronous motor without a position sensor, and is also the key point for realizing the smooth starting of the motor. Aiming at a surface-mounted permanent magnet synchronous motor, the existing detection method is based on the nonlinear saturation characteristic of a stator core of the motor, and the pulse vibration high-frequency injection method is adopted to realize initial position detection, but the method comprises multiple filtering operations, the calculated amount is large, the algorithm structure is complicated, and the method is not easy to realize in engineering application.

The initial position detection method often needs to judge the positive direction of the direct axis of the rotor. The method generally adopted is as follows: and passing the voltage pulses with the same width in the positive and negative directions to the straight shaft under the estimation coordinate system, and judging by using the current response generated by the voltage pulses. The method has higher requirements on the current sampling circuit, has certain difficulty in realization, and the sampling frequency of the system can influence the judgment accuracy of the system.

Disclosure of Invention

In view of this, the embodiment of the present invention provides a surface-mounted permanent magnet synchronous motor initial position detection method based on a combination of a hall position sensor and pulse vibration high-frequency injection, which can detect a rotor initial position of a surface-mounted permanent magnet synchronous motor, solve the problems of low estimation accuracy and low operation efficiency of a rotor position during a motor starting phase, and ensure smooth starting of the permanent magnet synchronous motor.

A surface-mounted permanent magnet synchronous motor initial position detection method based on combination of a Hall position sensor and pulse vibration high-frequency injection comprises the following steps:

(1) detecting the initial position of the rotor: the voltage U under the d-q axis is set by adopting a current open loop structure_d＝0， U_q0; injecting a high-frequency sinusoidal voltage signal U on a d axis by adopting a pulse vibration high-frequency injection method_incos(ω_ht) collecting the three-phase current I of the motor at the moment_a,I_b,I_cIs transformed into coordinates to obtain I_q(ii) a Will I_qModulating with high-frequency sinusoidal signal, and obtaining information containing position estimation error by low-pass filterTo pairThe signal integration obtains the initial position value of the rotorThe calculation method is that,

wherein k is_iTo integrate the gain, k_i＞0。

(2) Judging the positive direction of the straight axis: and reading signals of the three-phase Hall position sensor to obtain a Hall sector N where the current rotor is located.

(3) Actual initial angle calculation: judging the positive direction of the actual direct axis of the motor according to the Hall sector where the current rotor is positioned, and using the Hall sector N where the current rotor is positioned as a constraint condition to carry out initial position value on the rotorJudging whether compensation is needed or not, and finally obtaining the initial position theta of the actual rotor_final。

Further, the step (1) includes position estimation error informationThe calculation method is that,

the LPF selects an IIR type low-pass filter with less calculation amount to filter high-frequency harmonic amount, and the cut-off frequency is 200 Hz.

Further, the method for determining whether compensation is needed in step (3) is to determine the estimated initial position of the rotorWhether it is in the current hall sector, if it is in the current sector, thenIf not in the current sector, thenThe formula is as follows,

compared with the prior art, the method can detect the initial position of the rotor of the surface-mounted permanent magnet synchronous motor, and takes the current Hall sector as the given constraint of the initial angle, thereby avoiding magnetic pole judgment, reducing the calculation amount, solving the problems of low estimation precision and low calculation efficiency of the rotor position in the starting stage of the motor, and ensuring the smooth starting of the permanent magnet synchronous motor.

Drawings

FIG. 1 is a flow chart of a method for detecting an initial position of a surface-mounted permanent magnet synchronous motor according to the present invention;

FIG. 2 is a schematic diagram of the Hall position sensor output waveform of the present invention;

fig. 3 is a graph showing the characteristic of a direct-axis magnetic circuit ψ -i of the surface-mount permanent magnet synchronous motor of the present invention;

FIG. 4 is a diagram of the relationship of the coordinate systems of the motor of the present invention;

FIG. 5 is a dynamic equivalent circuit diagram of the surface-mounted permanent magnet synchronous motor of the present invention under a two-phase rotating coordinate system;

FIG. 6 is a block diagram of an equivalent unit negative feedback system of the present invention;

fig. 7 is a frame diagram of the motor rotor initial position detection operation of the present invention.

Detailed Description

In order to illustrate the technical solution of the present invention, the present invention is further described below with reference to the accompanying drawings and examples.

Example 1

As shown in fig. 1, a method for detecting an initial position of a surface-mounted permanent magnet synchronous motor includes the following steps,

(1) detecting the initial position of the rotor: the voltage U under the d-q axis is set by adopting a current open loop structure_d＝0，U_q0; injecting a high-frequency sinusoidal voltage signal U on a d axis by adopting a pulse vibration high-frequency injection method_incos(ω_ht) collecting the three-phase current I of the motor at the moment_a,I_b,I_cIs transformed into coordinates to obtain I_q(ii) a Will I_qModulating with high-frequency sinusoidal signal, and obtaining information containing position estimation error by low-pass filterTo pairThe signal integration obtains the initial position value of the rotorThe calculation method is that,

wherein k is_iTo integrate the gain, k_i＞0；

(2) Judging the positive direction of the straight axis: reading a signal of a three-phase Hall position sensor to obtain a Hall sector N where a current rotor is located;

(3) actual initial angle calculation: judging the positive direction of the actual direct axis of the motor according to the Hall sector where the current rotor is positioned, and using the Hall sector N where the current rotor is positioned as a constraint condition to carry out initial position value on the rotorJudging whether compensation is needed or not, and finally obtaining the initial position theta of the actual rotor_final。

Further, the step (1) includes position estimation error informationThe calculation method is that,

the LPF selects an IIR type low-pass filter with less calculation amount to filter high-frequency harmonic amount, and the cut-off frequency is 200 Hz.

Further, the method for determining whether compensation is needed in step (3) is that the rotor rotates for a circle and is averagely divided into six hall sectors, three hall signals are obtained, and the hall position sensor sectors are divided as shown in fig. 2; the estimated initial position of the rotor is judged by taking the current Hall sector as the given constraint of the initial angleWhether it is in the current hall sector, if it is in the current sector, thenIf not in the current sector, thenThe formula is as follows,

further, the pulse oscillation high-frequency injection method in the step (1) has the principle that after the pulse oscillation signal is injected, because the permanent magnet synchronous motor has salient pole rate, the current feedback signal contains position information, and the position information is extracted through a signal processing technology; the salient pole rate of the surface-mounted permanent magnet synchronous motor is very small, but a saturated salient pole effect exists under a pulse vibration signal, so that the pulse vibration high-frequency injection method can be applied to the surface-mounted permanent magnet synchronous motor; wherein psi-i characteristic curve of motor straight-axis magnetic circuit is shown in FIG. 3, i_fThe working point of the straight-axis magnetic circuit is i_fIt is determined that the design is usually designed such that the magnetic circuit is close to the saturation point, as indicated by point A, and the corresponding direct-axis inductance value is L_d(ii) a When in straightA certain forward current i is introduced to the shaft_d ⁺At the moment, the direction of the magnetic field generated by the permanent magnet is consistent with that of the magnetic field generated by the direct-axis current, the direct-axis magnetic circuit is saturated, and the corresponding direct-axis inductance value is L_d ⁺(ii) a When a certain negative current i is introduced to the straight shaft_d ^-When the magnetic circuit is in linear section, the corresponding inductance value of the straight axis is L_d ^-(ii) a The following relationship can be derived from the figure:

L_d ⁺＜L_d≈L_d ^-； (1)

the psi-i characteristic curve of the quadrature-axis magnetic circuit is basically the same as that of the direct-axis magnetic circuit, but the working point is at the original point, the magnetic circuit is in a linear section, the saturation phenomenon cannot occur, and the following relational expression can be obtained:

L_q ⁺＝L_q ^-＝L_q； (2)

since the orthogonal and orthogonal axes psi-i characteristic curves are substantially the same, L can be considered as_q≈L_d ^-. Therefore, if proper direct-axis forward current is introduced, the direct-axis inductance of the surface-mounted permanent magnet synchronous motor can be smaller than the quadrature-axis inductance, namely L_d ⁺＜L_q. At the moment, the surface-mounted permanent magnet synchronous motor can generate a salient pole rate, and the position of a motor rotor can be detected by adopting a pulse vibration high-frequency injection method.

The principle for detecting the position of the motor rotor by the pulse vibration high-frequency injection method in the step 1 is that the estimation error of the rotor position is definedIs composed of

Wherein the actual rotor position value theta, the estimated rotor position valueAnd position estimation errorThe relationship between the three is shown in FIG. 4. Where d-q is the actual two-phase rotating coordinate system,is an estimated two-phase rotating coordinate system. There is a relationship that,

whereinAndrespectively representing the direct and alternating axis voltages and currents under the estimated two-phase rotating coordinate system.

The dynamic equivalent circuit of the surface-mounted permanent magnet synchronous motor in a two-phase rotating coordinate system is shown in figure 5, and when the motor is in a static state, the voltage equation can be simplified into

Wherein Z is_d、Z_qImpedance of the direct axis and quadrature axis.

With the combination of equations (4), (5) and (6), the estimated current response in the two-phase rotating coordinate system is obtained as,

order toThen Z_d＝Z+ΔZ、Z_qAs Z- Δ Z, formula (7) is simplified to

To extract the position estimation error Δ θ, a high frequency voltage signal may be applied to the straight axis in the estimated two-phase rotational coordinate systemThe current response is solved by substituting the equation (8),

to the formula (9)Appropriate transformations are performed. Δ Z can be expressed as

Wherein the content of the first and second substances,substituting formula (10) for formula (9) only forMake the following changes

Wherein|Z_d|、|Z_qI andthe high-frequency impedance amplitude and the phase angle of the d axis and the q axis are respectively.

From the formula (11), by detecting the currentAfter passing through multiplier and Low Pass Filter (LPF), obtaining information containing position estimation error

Wherein

When the estimated initial position of the rotor is sufficiently close to the actual initial position, i.e. whenAt this timeTo pairAfter signal integration, an initial estimation value of the rotor position is obtained, and the formula can be obtained as follows,

equation (13) can be equivalent to a unit negative feedback system, and its structure is shown in fig. 6. The system is an I-type system and can realize the non-static tracking of the estimated initial position to the actual position.

The initial position detection and operation framework of the motor rotor in the embodiment of the invention is shown in figure 7, compared with the traditional pulse vibration high-frequency injection method, a band-pass filter and a phase-locked loop structure are omitted, the algorithm is simpler and more convenient, and meanwhile, the current Hall sector is used as given constraint of an initial angle, and the direction of a straight axis of the rotor can be directly determined, so that magnetic pole judgment is avoided, and the operation amount is reduced. The problems of low rotor position estimation precision and low operation efficiency in the starting stage of the motor are solved, and the smooth starting of the permanent magnet synchronous motor is ensured.