A position sensorless control method for low torque pulsation dual three-phase permanent magnet motor

Abstract

The present invention discloses a low torque pulsation dual three-phase permanent magnet motor position sensorless control method. Under the dual dq control structure, the method establishes a virtual rotating coordinate system in two sets of three-phase windings respectively, and injects a pulse voltage signal into the virtual rotating coordinate system. By adjusting the phase difference of the injected signal in the two sets of windings, the synthetic torque pulsation caused by the injected signal is made zero, thereby reducing the torque pulsation caused by the injected voltage signal. The method retains the advantages of the virtual pulse injection method such as fast position estimation convergence speed and no need for bandpass filter participation. While ensuring good position identification accuracy, it solves the torque pulsation problem caused by the injection of virtual pulse voltage signals, and further improves the application prospects of the dual three-phase permanent magnet motor high-frequency signal injection method position sensorless control.

Description

Technical Field

[0001] The present invention belongs to the field of permanent magnet synchronous motor drive control application, and in particular relates to a position sensorless control method for a low torque pulsation dual three-phase permanent magnet motor. Background Art

[0002] Multiphase permanent magnet motors have the advantages of high torque density, high efficiency, and high reliability. They have broad application prospects in new energy vehicles, aerospace, ship propulsion and other fields. Dual three-phase permanent magnet motors have the advantages of multiphase permanent magnet motors and are more advantageous in torque performance. Dual three-phase permanent magnet synchronous motors have two sets of three-phase windings that are 30° apart in space, making them more flexible in control methods. In order to achieve high-performance control of permanent magnet synchronous motors, motor rotor position information is indispensable. However, mechanical position sensors increase system weight and cost, and in some extreme applications, they also face reliability issues. High-frequency signal injection method is an effective low-speed position sensorless control scheme. However, the demodulation of the position signal in the high-frequency signal injection method usually requires the participation of a bandpass filter, and the high-frequency torque pulsation problem caused by the injection signal deserves special attention. Therefore, it is of great practical significance to study the high-frequency signal injection method with simple structure and low torque pulsation to improve the low-speed position sensorless control performance.

[0003] In order to achieve position sensorless control at low speed, domestic and foreign scholars have conducted relevant research on the high-frequency signal method. The Chinese invention patent "A sensorless initial position detection method for a permanent magnet synchronous motor" (patent number: CN107171608B) discloses a sensorless initial position detection method for a permanent magnet synchronous motor, which uses a virtual pulse high-frequency injection method to solve the rotor position, injects a high-frequency voltage into the virtual direct axis, and establishes a virtual rotating coordinate system. Using the mathematical model of this coordinate system and the permanent magnet synchronous motor coordinate system, the direct axis and quadrature axis currents are solved, and finally the rotor position is obtained by taking the inverse tangent of the two currents. Although the structure of this method is relatively simple, the injected signal will form high-frequency torque pulsation on the q-axis, which will directly affect the position sensorless control performance. The Chinese invention patent "A method for controlling a six-phase permanent magnet motor without a position sensor by high-frequency injection of inverse double frequency synchronous coordinate pulses to suppress torque pulsation" (patent number: CN114123901A) discloses a method for controlling a six-phase permanent magnet motor without a position sensor by high-frequency injection of inverse double frequency synchronous coordinate pulses to suppress torque pulsation. The method injects two sets of high-frequency signals with a difference of 180° into two sets of three-phase windings, eliminates the torque pulsation of the inverse double frequency synchronous coordinate algorithm, and finally obtains the estimated position of the motor rotor by demodulating the zero-sequence voltage. However, this method ignores the component of the injected voltage signal mapped to the d-axis, which makes d-axis current tracking more difficult. Therefore, how to take into account the complexity of signal demodulation on the basis of the high-frequency signal injection method, while not bringing in additional high-frequency torque pulsation, and achieve low torque pulsation position sensorless control is the main factor considered by the present invention. Summary of the invention

[0004] In order to solve the torque pulsation problem caused by virtual pulsation injection position sensorless control, the present invention proposes a low torque pulsation dual three-phase permanent magnet motor position sensorless control method, which adjusts the phase of the high-frequency signal injected into the two sets of windings so that the synthesized high-frequency torque pulsation is zero. Under the premise of ensuring the motor position sensorless control performance, the torque pulsation caused by the injection of high-frequency voltage signals is weakened.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a position sensorless control method for a low torque pulsation dual three-phase permanent magnet motor, the implementation steps of which include:

[0007] Step 1: establish a virtual rotating coordinate system in the two sets of three-phase windings of the dual three-phase permanent magnet motor, and inject a pulse voltage signal into the virtual coordinate system. Analyze the torque pulsation caused by the injected signal, and adjust the injected signals in the two sets of windings so that the synthesized torque pulsation cancels each other out.

[0008] Step 2: Analyze the current response generated after injecting the high-frequency voltage signal, process the high-frequency current response, use a low-pass filter to filter out other high-frequency signals, extract the part containing the rotor position information, and obtain the motor rotor position angle and speed after orthogonal phase-locked loop processing.

[0009] Step 3, using a dual dq control structure, the estimated position angle and speed information are fed back to the dual three-phase permanent magnet motor control system to complete position sensorless control.

[0010] Further, the specific process of step 1 is:

[0011] Assume that the motor rotor is moving at a very high speed ω v t rotation, constructing a virtual two-phase rotating coordinate system dq r * Injecting a pulse voltage signal into this virtual coordinate system does not require the participation of a bandpass filter, which is conducive to the separation of high-frequency current response signals. The rotation angular frequency of the virtual coordinate system is set to be much larger than the maximum frequency of the motor operation, and the virtual rotating coordinate system established in the two sets of three-phase windings maintains the same frequency.

[0012] When the fundamental wave and other high-order harmonics are ignored and only the pulse high-frequency voltage signal is injected, the pulse voltage signal injected in the virtual rotating coordinate system is

[0013]

[0014] In the formula, u dinj and u qinj are the injected voltage in the virtual dq coordinate system, U h is the amplitude of the injected voltage, ω h is the angular frequency of the injected voltage.

[0015] Inject the pulse signal into the virtual rotating coordinate system, and the voltage of the virtual αβ axis is

[0016]

[0017] In the formula, u vα ,u vβ is the voltage of the virtual αβ axis, ω v is the angular velocity of rotation of the virtual coordinate system.

[0018] When dual dq control is adopted, taking ABC winding as an example, the voltage equation of the dual three-phase permanent magnet motor in the rotating coordinate system can be expressed as

[0019]

[0020] In the formula, u d ,u q is the voltage of dq axis, id ,i q is the current in the dq axis, L d , L q is the dq axis inductance, ω e is the electrical angular velocity, ψ f is the permanent magnet flux, R s is the stator resistance.

[0021] Taking winding ABC as an example, when the motor is running at low speed and a high-frequency signal is injected, the effects of resistance, back electromotive force and cross-coupling terms in the motor can be ignored. At this time, the voltage equation is equivalent to a pure inductance equation, which is expressed as

[0022]

[0023] At this time, the real high-frequency current response of the dq axis is obtained as follows:

[0024]

[0025] In the formula, i dh and i qh is the dq axis high frequency response current, θ r is the motor rotor position angle. It can be seen that even in steady state, the q-axis high-frequency current is still not zero. For the surface-mounted permanent magnet synchronous motor, the torque caused by the difference in dq-axis inductance is ignored. The high-frequency torque pulsation generated by further calculation is

[0026]

[0027] In the formula, P is the number of motor pole pairs. It can be seen from the above formula that the high-frequency pulse voltage injection based on the virtual coordinate system will bring about a certain torque pulsation, and the magnitude of the torque pulsation is positively correlated with the amplitude of the injected voltage signal.

[0028] When the surface-mounted dual three-phase permanent magnet motor adopts dual dq control, a virtual coordinate system is established in the two sets of three-phase windings, and a pulse voltage signal is injected as

[0029]

[0030]

[0031] In the formula, u dinj1 and u qinj1 、u dinj1 and u qinj1 are the injected voltages of windings ABC and DEF respectively. At this time, considering that the two sets of windings are 30 degrees apart in space, ignoring the influence of the orthogonal axis inductance difference and mutual inductance, the high-frequency torque pulsation can be expressed as

[0032]

[0033] When the amplitude and phase of the injected voltage in the two windings are adjusted to

[0034]

[0035] At this time, the synthesized high-frequency torque pulsation is 0, thus greatly reducing the high-frequency torque pulsation caused by the injected signal.

[0036] Further, the specific process described in step 2 is:

[0037] After coordinate transformation, the injected voltage can be converted into the actual synchronous rotating coordinate system, that is,

[0038]

[0039] When the motor runs at low speed, the effect of back EMF is ignored. According to the voltage equation, the current in the rotating coordinate system can be obtained as

[0040]

[0041] In the formula, i dh and i qh are the high-frequency current responses of the dq axis respectively, so further, the current response of the virtual coordinate system is obtained as follows:

[0042]

[0043] The current response of the virtual coordinate system is written in vector form as

[0044]

[0045] In the formula,

[0046]

[0047]

[0048]

[0049] The composite signal cos(ω h t)·cos(2ω v t) is multiplied by the above formula to obtain the component related to the rotor position:

[0050]

[0051]

[0052] In the formula, i * dqH is the high frequency component contained in the current.

[0053] After filtering out the high-frequency signal with a low-pass filter, the low-frequency component containing the rotor position information is obtained:

[0054]

[0055] Further rewrite the above formula into

[0056]

[0057] In the formula,

[0058]

[0059]

[0060] Among them, the position estimation error It can be calculated in advance based on the motor parameters. For surface-mounted permanent magnet motors, since the motor dq axis inductance is equal (i.e. L d =L q ), so the position error is zero. Therefore, the above formula is further simplified to

[0061]

[0062] In the formula, and is a pair of orthogonal current components. From the above formula, it can be seen that the rotor position angle θ r It can be obtained through a phase-locked loop position observer. After the current with high-frequency signals filtered out is normalized, the position error can be obtained through an orthogonal phase-locked loop observer, which is expressed as

[0063]

[0064]

[0065] The calculated position estimation error After subtraction, the position error is tracked by the proportional integral controller (PI). When the position error is zero, it means that the estimated position angle is equal to the true position angle. At this time, the estimated position angle and speed of the motor are obtained.

[0066] Further, the specific process of step 3 is:

[0067] The estimated speed is subtracted from the given speed to form a speed closed loop. The speed difference is passed through a PI controller to obtain the iq given values ​​of the two sets of windings. The estimated position angle is then fed back to the Parker transformation matrix to obtain the dq axis currents of the two sets of windings, forming a current closed loop.

[0068] Beneficial effects of the present invention:

[0069] 1) The signal injection method proposed in the present invention makes the high-frequency torques in the two sets of windings cancel each other out, thereby suppressing the torque pulsation caused by the injected signal;

[0070] 2) The present invention can obtain better position identification accuracy and realize position sensorless control of dual three-phase permanent magnet motors at low speed;

[0071] 3) The present invention adopts a virtual pulse injection method and is not affected by the cross saturation effect of the motor;

[0072] 4) The position demodulation in the present invention does not require a bandpass filter, so the structure is simpler;

[0073] 5) The present invention is applicable to both surface mounted and embedded dual three-phase permanent magnet synchronous motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 A block diagram of a low torque pulsation dual three-phase permanent magnet motor without position sensor control according to an embodiment of the present invention;

[0075] Figure 2 A distribution diagram of each coordinate system of an embodiment of the present invention;

[0076] Figure 3 A block diagram of a virtual pulse signal injection according to an embodiment of the present invention;

[0077] Figure 4 A structural block diagram of high frequency signal processing according to an embodiment of the present invention;

[0078] Figure 5 This is the torque waveform diagram of the traditional virtual pulse injection method;

[0079] Figure 6 A torque waveform diagram of the proposed method according to an embodiment of the present invention;

[0080] Figure 7 A position angle comparison diagram of an embodiment of the present invention;

[0081] Figure 8 This is a rotation speed comparison diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0082] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0083] like Figure 1 As shown, the present invention proposes a position sensorless control method for a low torque pulsation dual three-phase permanent magnet motor.

[0084] The specific implementation steps of the proposed low torque pulsation dual three-phase permanent magnet motor position sensorless control method include:

[0085] Step 1: Inject virtual pulse voltage signals into two sets of three-phase windings:

[0086] Assume that the motor rotor is moving at a very high speed ω v t rotation, constructing a virtual two-phase rotating coordinate system dq r * . Figure 2 The distribution diagram of each coordinate system. Injecting the pulse voltage signal into the virtual coordinate system does not require the participation of the bandpass filter, which is conducive to the separation of the high-frequency current response signal. The rotation angular frequency of the virtual coordinate system is set to be much larger than the maximum frequency of the motor operation, and the virtual rotating coordinate system established in the two sets of three-phase windings maintains the same frequency.

[0087] When the fundamental wave and other high-order harmonics are ignored and only the pulse high-frequency voltage signal is injected, the pulse voltage signal injected in the virtual rotating coordinate system is:

[0088]

[0089] In the formula, u dinj and u qinj are the injected voltage in the virtual dq coordinate system, U h is the amplitude of the injected voltage, ω h is the angular frequency of the injected voltage.

[0090] like Figure 3 As shown, the pulse signal is injected into the virtual rotating coordinate system, and the voltage of the virtual αβ axis is obtained as

[0091]

[0092] In the formula, u vα ,u vβ is the voltage of the virtual αβ axis, ω v is the angular velocity of rotation of the virtual coordinate system.

[0093] When dual dq control is adopted, taking ABC winding as an example, the voltage equation of the dual three-phase permanent magnet motor in the rotating coordinate system can be expressed as:

[0094]

[0095] In the formula, u d ,u q is the voltage of dq axis, i d ,i q is the current in the dq axis, L d , L q is the dq axis inductance, ω eis the electrical angular velocity, ψ f is the permanent magnet flux, R s is the stator resistance.

[0096] Taking winding ABC as an example, when the motor is running at low speed and a high-frequency signal is injected, the effects of resistance, back electromotive force and cross-coupling terms in the motor can be ignored. At this time, the voltage equation is equivalent to a pure inductance equation, which is expressed as

[0097]

[0098] At this time, the real high-frequency current response of the dq axis is obtained as follows:

[0099]

[0100] In the formula, i dh and i qh is the dq axis high frequency response current, θ r is the motor rotor position angle. It can be seen that even in steady state, the q-axis high-frequency current is still not zero. For surface-mounted permanent magnet synchronous motors, the torque caused by the difference in dq-axis inductance is ignored. The high-frequency torque pulsation generated by further calculation is:

[0101]

[0102] In the formula, P is the number of motor pole pairs. It can be seen from the above formula that the high-frequency pulse voltage injection based on the virtual coordinate system will bring about a certain torque pulsation, and the magnitude of the torque pulsation is positively correlated with the amplitude of the injected voltage signal.

[0103] When the surface-mounted dual three-phase permanent magnet motor adopts dual dq control, a virtual coordinate system is established in the two sets of three-phase windings, and a pulse voltage signal is injected as

[0104]

[0105]

[0106] In the formula, u dinj1 and u qinj1 、u dinj1 and u qinj1 are the injected voltages of windings ABC and DEF respectively. At this time, considering that the two sets of windings are 30 degrees apart in space, ignoring the influence of the orthogonal axis inductance difference and mutual inductance, the high-frequency torque pulsation can be expressed as

[0107]

[0108] When the amplitude and phase of the injected voltage in the two windings are adjusted to

[0109]

[0110] At this time, the synthesized high-frequency torque pulsation is 0, thus greatly reducing the high-frequency torque pulsation caused by the injected signal.

[0111] Step 2: Extract the high frequency current response to demodulate the position information:

[0112] After coordinate transformation, the injected voltage can be converted into the actual synchronous rotating coordinate system, that is,

[0113]

[0114] When the motor runs at low speed, the effect of back EMF is ignored. According to the voltage equation, the current in the rotating coordinate system can be obtained as

[0115]

[0116] In the formula, i dh and i qh are the high-frequency current responses of the dq axis respectively, so further, the current response of the virtual coordinate system is obtained as follows:

[0117]

[0118] The current response of the virtual coordinate system is written in vector form as

[0119]

[0120] In the formula,

[0121]

[0122]

[0123]

[0124] The composite signal cos(ω h t)·cos(2ω v t) is multiplied by the above formula to obtain the component related to the rotor position:

[0125]

[0126]

[0127] In the formula, i * dqH is the high frequency component contained in the current.

[0128] After filtering out the high-frequency signal with a low-pass filter, the low-frequency component containing the rotor position information is obtained:

[0129]

[0130] Further rewrite the above formula into

[0131]

[0132] In the formula,

[0133]

[0134]

[0135] Among them, the position estimation error It can be calculated in advance based on the motor parameters. For surface-mounted permanent magnet motors, since the motor dq axis inductance is equal (i.e. L d =L q ), so the position error is zero. Therefore, the above formula is further simplified to

[0136]

[0137] In the formula, and is a pair of orthogonal current components. From the above formula, it can be seen that the rotor position angle θ r It can be obtained through a phase-locked loop position observer.

[0138] After filtering out the high-frequency signal, the current is normalized and the position error is obtained through an orthogonal phase-locked loop observer, which is expressed as

[0139]

[0140]

[0141] The calculated position estimation error After subtraction, the position error is tracked by the proportional integral controller (PI). When the position error is zero, it means that the estimated position angle is equal to the true position angle. At this time, the estimated position angle and speed of the motor are obtained. Figure 4 This is a structural block diagram of high-frequency signal processing.

[0142] Step 3: Feedback the estimated position angle and speed to the closed-loop control system:

[0143] The estimated speed is subtracted from the given speed to form a speed closed loop. The speed difference is passed through a PI controller to obtain the iq given values ​​of the two sets of windings. The estimated position angle is then fed back to the Parker transformation matrix to obtain the dq axis currents of the two sets of windings, forming a current closed loop.

[0144] Figure 5 and Figure 6The torque waveforms of the traditional virtual pulsation injection method and the proposed method are shown respectively. It can be seen that the proposed method can eliminate high-frequency torque pulsation and the torque waveform is smoother; Figure 7 and Figure 8 They are the comparison diagrams of motor position angle and speed respectively. It can be seen from the figure that the estimated value in the proposed method can track the actual value well and has a good position estimation effect.

[0145] The above embodiments are only used to illustrate the design ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. Therefore, any equivalent changes or modifications made based on the principles and design ideas disclosed by the present invention are within the protection scope of the present invention.

Claims

1. A low torque pulsation dual three-phase permanent magnet motor position sensorless control method, It is characterized in that Includes the following step: Step 1, respectively establish a virtual rotating coordinate system in the two sets of three-phase windings of the dual three-phase permanent magnet motor, inject a pulse high-frequency voltage signal into the virtual coordinate system, set the rotation angular frequency of the virtual coordinate system to be much larger than the maximum frequency of the motor operation, and at the same time, maintain the same frequency for the virtual rotating coordinate system established in the two sets of three-phase windings; analyze the torque pulsation caused by the injected signal, adjust the injected signal in the two sets of windings so that the synthesized torque pulsation cancels each other out. Specifically, when the surface-mounted dual three-phase permanent magnet motor adopts dual dq control, a virtual coordinate system is established in the two sets of three-phase windings, and the pulse voltage signal is injected as follows: In the formula, u dinj and u qinj are the injected voltage in the virtual dq coordinate system, U h is the amplitude of the injected voltage, ω h is the angular frequency of the injected voltage; High-frequency torque ripple is expressed as: Where p is the number of motor pole pairs, ω v is the angular velocity of the virtual rotating coordinate system, i qh is the high frequency response current, subscripts 1 and 2 represent winding ABC and winding DEF respectively, θ r is the motor rotor position angle, ψ f is the permanent magnet flux of the motor, L q is the q-axis inductance of the motor; according to the trigonometric function and differential product formula, the amplitude and phase of the injected voltage in the two sets of windings are adjusted as follows: At this time, according to the sum-difference-product formula, the expression of high-frequency torque is rewritten as When v1 t-ω h1 t=θ r When , the synthesized high-frequency torque pulsation is 0; Step 2, analyzing the current response generated after the high-frequency voltage signal is injected, processing the high-frequency current response, filtering out other high-frequency signals using a low-pass filter, extracting the part containing the rotor position information, and obtaining the motor rotor position angle and speed after processing by an orthogonal phase-locked loop; Step 3, using a dual dq control structure, feeding back the position angle and speed information obtained in step 2 to the dual three-phase permanent magnet motor control system to complete position sensorless control.

2. The low torque pulsation dual three-phase permanent magnet motor position sensorless control method according to claim 1, It is characterized in that The specific steps of establishing a virtual rotating coordinate system in step 1 include: The motor rotor has a speed of ω v t rotation, constructing a virtual two-phase rotating coordinate system dq r * , a pulse voltage signal is injected into this virtual coordinate system; the rotation angular frequency of the virtual coordinate system is set to be much larger than the maximum frequency of the motor operation, and the virtual rotating coordinate systems established in the two sets of three-phase windings maintain the same frequency.

3. The low torque pulsation dual three-phase permanent magnet motor position sensorless control method according to claim 2, It is characterized in that The specific steps of injecting the pulse voltage signal into the virtual coordinate system in step 1 include: Ignore the fundamental wave and other high-order harmonics, and only consider the injected pulse high-frequency voltage signal. The injected pulse voltage signal in the virtual rotating coordinate system is: In the formula, u dinj and u qinj are the injected voltage in the virtual dq coordinate system, U h is the amplitude of the injected voltage, ω h is the angular frequency of the injected voltage; Inject the pulse signal into the virtual rotating coordinate system, and the voltage of the virtual αβ axis is: In the formula, u vα ,u vβ is the voltage of the virtual αβ axis, ω v is the angular velocity of rotation of the virtual coordinate system.

4. The low torque pulsation dual three-phase permanent magnet motor position sensorless control method according to claim 3, It is characterized in that The torque ripple caused by the injected signal in step 1 is analyzed as follows: Analyze the high-frequency torque pulsation generated by the surface-mounted permanent magnet synchronous motor, ignore the torque caused by the difference in dq axis inductance, and further calculate the high-frequency torque pulsation generated: In the formula, i qh is the high frequency response current, ψ f is the permanent magnet flux, L q is the q-axis inductance of the motor; from the above analysis, it can be seen that the high-frequency pulse voltage injection based on the virtual coordinate system will bring about a certain torque pulsation, and the magnitude of the torque pulsation is positively correlated with the amplitude of the injected voltage signal.

5. The low torque pulsation dual three-phase permanent magnet motor position sensorless control method according to claim 1, It is characterized in that The specific steps of analyzing the current response generated after injecting the high-frequency voltage signal in step 2 include: The injected voltage is transformed into the actual synchronous rotating coordinate system through coordinate transformation. When the motor runs at low speed, the influence of back electromotive force is ignored. According to the voltage equation, the current in the rotating coordinate system is obtained, and the current response of the virtual coordinate system is further obtained, which is expressed as: In the formula, i dh and i qh They are the high-frequency current responses of the dq axes respectively.

6. The low torque pulsation dual three-phase permanent magnet motor position sensorless control method according to claim 5, It is characterized in that In step 2, the high-frequency current response is processed as follows: the current response of the virtual coordinate system is written in vector form to obtain the component related to the rotor position. Specifically, The vector form of the current response in the virtual coordinate system is: In the formula, is the high-frequency current response of the virtual dq axis, I represents the current component, represents the offset angle, subscripts p and q represent the positive and negative sequence components respectively, subscripts 1 and 2 represent the first and second components in the positive and negative sequence current responses respectively. For the negative sequence current component, its current expression is further written as: In the formula, R s is the stator resistance, L d and L q are the motor dq axis inductance respectively; The composite signal cos(ω h t)·cos(2ω v t) is multiplied by the above formula to obtain the component related to the rotor position: In the formula, i * dqH is the high frequency component contained in the current.

7. The low torque pulsation dual three-phase permanent magnet motor position sensorless control method according to claim 6, It is characterized in that In step 2, a low-pass filter is used to obtain the low-frequency component containing the rotor position information, which is expressed as: The above formula is further simplified to the square root form of the intermediate vector, expressed as: In the formula, is the low frequency current component, and is a pair of orthogonal current components, I 1nx and I 2nx is a pair of intermediate variables; it can be seen from the above formula that the rotor position angle θ r It can be obtained through a phase-locked loop position observer.

8. The low torque pulsation dual three-phase permanent magnet motor position sensorless control method according to claim 7, It is characterized in that The specific steps of obtaining the motor rotor position angle and speed after orthogonal phase-locked loop processing in step 2 include: After filtering out the high-frequency signal, the current is normalized and the position error is obtained through an orthogonal phase-locked loop observer, which is expressed as: In the formula, To estimate the position angle, Δθ r is the position error, The calculated position estimation error After subtraction, the position error is tracked by the proportional integral controller PI. When the position error is zero, it means that the estimated position angle is equal to the true position angle. At this time, the estimated position angle and speed of the motor are obtained.

9. The low torque pulsation dual three-phase permanent magnet motor position sensorless control method according to claim 1, It is characterized in that The specific steps in step 3 include: subtracting the estimated speed from the given speed to form a speed closed loop, and the speed difference is passed through a PI controller to obtain the iq given value of the two sets of windings; then the estimated position angle is fed back to the Park transformation matrix to obtain the dq axis current of the two sets of windings to form a current closed loop.

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