A high-efficiency control method for multi-phase permanent magnet synchronous motor

Abstract

The present invention discloses a highly efficient control method for a multiphase permanent magnet synchronous motor. Based on the extreme value search principle, a model of the electromagnetic torque and current vector angle of the multiphase permanent magnet synchronous motor is established. A virtual high-frequency signal is superimposed on the current vector angle, and an extreme value search process is designed. By detecting whether the partial differential of the electromagnetic torque term with respect to the current vector angle term is zero, the optimal current vector angle is searched. This method enables the multiphase permanent magnet synchronous motor to generate maximum electromagnetic torque under a certain current amplitude, thereby reducing motor copper loss. The highly efficient control method for a multiphase permanent magnet synchronous motor disclosed by the present invention has the advantages of a simple control structure, easy implementation, and low dependence on motor parameters.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor control, and in particular relates to a high-efficiency control method for a multi-phase permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors have the advantages of high power factor and high torque density. They have been widely used in electric transmission, electric vehicles, ship propulsion and other fields. The use of efficient motor control strategies is of great significance to increasing motor efficiency, reducing energy consumption and extending cruising range.

[0003] To improve motor efficiency, existing research literature uses experimental methods to determine the current vector angle under different motor torque commands. The relationship between the current vector angle and the torque command is then fitted or stored in a data table within the motor controller. During motor operation, the current vector angle stored in the data table is directly retrieved based on the motor torque command to achieve efficient motor control. However, the table lookup method suffers from limited versatility, requiring different data tables for different motors. Summary of the Invention

[0004] In view of the above problems, the object of the present invention is to provide an efficient control method for a multi-phase permanent magnet synchronous motor, which has the advantages of simple control structure, easy implementation, and low dependence on motor parameters.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a high-efficiency control method for a multi-phase permanent magnet synchronous motor, comprising the following steps:

[0006] Step 1: Construct the equivalent electromagnetic torque model of the multi-phase permanent magnet synchronous motor in the dq axis system:

[0007]

[0008] Among them L d is the equivalent d-axis inductance of the motor, L q is the equivalent q-axis inductance of the motor, ψ m is the permanent magnet flux of the motor, i dequ 、i qequ They are the equivalent d-axis current component and equivalent q-axis current component of the motor, P n is the number of motor pole pairs;

[0009] According to the dq axis current of each set of three-phase windings, the equivalent dq axis current components of the multi-phase permanent magnet synchronous motor are obtained:

[0010]

[0011] where i dq1 、i dq2 、…、i dqNare the dq axis current components of the first, second, ..., Nth three-phase windings of the multi-phase permanent magnet synchronous motor respectively;

[0012] Step 2: Superimpose a virtual high-frequency signal on the current vector angle to construct an equivalent electromagnetic torque model of the multi-phase permanent magnet synchronous motor after superimposing the high-frequency disturbance signal:

[0013]

[0014] Where T e h Represents the electromagnetic torque of the multi-phase permanent magnet synchronous motor after superimposing the high-frequency disturbance signal;

[0015] Step 3: Design the extreme value search process:

[0016] Step 3.1: The electromagnetic torque T of the multi-phase permanent magnet synchronous motor after superimposing the high-frequency disturbance signal e h After being processed by bandpass filter, the high-frequency components in the electromagnetic torque are extracted;

[0017] Step 3.2, the high frequency electromagnetic torque component is compared with sin(ω h t) After multiplication, the DC component is obtained by low-pass filter processing;

[0018] Step 3.3, design the integration link, integrate the DC component obtained in step 3.2 to obtain the optimal current vector angle

[0019] Step 4: Search for the optimal current vector angle by detecting whether the partial differential of the electromagnetic torque term with respect to the current vector angle term is zero.

[0020] Furthermore, the high-frequency signal superimposed on the electromagnetic torque of the motor in step 2 is in the form of:

[0021]

[0022]

[0023] in i q h is the equivalent d-axis and q-axis current components after the high-frequency disturbance signal is superimposed on the current vector angle β, I s is the current vector amplitude, A mag is the amplitude of the high-frequency disturbance signal, ω h is the frequency of the high-frequency disturbance signal.

[0024] Furthermore, the transfer function of the bandpass filter in step 3.1 is:

[0025]

[0026] where ω f Represents the resonant frequency of the bandpass filter, take ω f =ω h .

[0027] Furthermore, the cutoff frequency of the low-pass filter included in step 3.2 is (1 / 10)ω h .

[0028] Furthermore, based on the optimal current vector angle, the reference current amplitude calculated by the speed outer loop is decomposed to obtain the reference value of the dq-axis current inner loop, thereby realizing efficient control of the multi-phase permanent magnet synchronous motor.

[0029] The beneficial effects of the present invention are as follows: the present invention generates the optimal current vector angle by designing an extreme value search link instead of the existing table search, and generates the maximum electromagnetic torque under a certain current amplitude, thereby reducing copper loss and improving motor efficiency; the control method of the present invention has the advantages of a simple control structure, simplified control parameter setting, and low dependence on motor parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a control block diagram of a multi-phase permanent magnet synchronous motor according to the present invention;

[0031] Figure 2 Implementation block diagram of the control method of the present invention;

[0032] Figure 3 1 is a structural block diagram of the bandpass filter of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below with reference to the accompanying drawings and examples.

[0034] like Figure 1 As shown, the present invention discloses a highly efficient control method for a multi-phase permanent magnet synchronous motor. This method utilizes the motor's three-phase current and voltage information, and generates an optimal current vector angle after calculation using an efficient control algorithm. The reference current amplitude calculated by the outer speed loop is decomposed to obtain reference values ​​for the dq-axis current inner loop, achieving highly efficient control of the multi-phase permanent magnet synchronous motor. The specific steps are as follows.

[0035] Step 1: Construct the equivalent electromagnetic torque model of the multi-phase permanent magnet synchronous motor in the dq axis system (Formula 1):

[0036]

[0037] Among them L d is the equivalent d-axis inductance of the motor, L q is the equivalent q-axis inductance of the motor, ψ mis the permanent magnet flux of the motor, i dequ 、i qequ They are the equivalent d-axis current component and equivalent q-axis current component of the motor, P n is the number of motor pole pairs.

[0038] Based on the dq-axis current of each three-phase winding, the equivalent dq-axis current components of the multi-phase permanent magnet synchronous motor are obtained (Formula 2):

[0039]

[0040] where i dq1 、i dq2 、…、i dqN They are the dq-axis current components of the first, second, ..., and Nth three-phase windings of the multi-phase permanent magnet synchronous motor respectively.

[0041] Step 2: Superimpose a virtual high-frequency signal on the current vector angle to construct an equivalent electromagnetic torque model of the multi-phase permanent magnet synchronous motor after superimposing the high-frequency disturbance signal (Formula 4):

[0042]

[0043] Where T e h Represents the electromagnetic torque of the multi-phase permanent magnet synchronous motor after the high-frequency disturbance signal is superimposed.

[0044] The high-frequency signal superimposed on the motor electromagnetic torque in this step is in the form of (Formula 3):

[0045]

[0046]

[0047] in i q h is the equivalent d-axis and q-axis current components after the high-frequency disturbance signal is superimposed on the current vector angle β, I s is the current vector amplitude, A mag is the amplitude of the high-frequency disturbance signal, ω h is the frequency of the high-frequency disturbance signal.

[0048] Step 3: Design an extreme value search process to find the optimal current vector angle by detecting whether the partial differential of the electromagnetic torque term with respect to the current vector angle term is zero. The specific steps are as follows.

[0049] Step 3.1: The electromagnetic torque T of the multi-phase permanent magnet synchronous motor after superimposing the high-frequency disturbance signal e h After being processed by a bandpass filter, the high-frequency components of the electromagnetic torque are extracted.

[0050] The transfer function of the bandpass filter in this step is:

[0051]

[0052] where ω f Represents the resonant frequency of the bandpass filter, take ω f =ω h .

[0053] Step 3.2, the high frequency electromagnetic torque component is compared with sin(ω h t) after multiplication and processed by low-pass filter to obtain the DC component. The cutoff frequency of the low-pass filter is (1 / 10)ω h .

[0054] Step 3.3: Design the integration link to integrate the DC component obtained in step 3.2 to obtain the optimal current vector angle.

[0055] Figure 2 This is the implementation block diagram of the efficient control algorithm for multi-phase permanent magnet synchronous motor. dq1 、i dq2 、…、i dqN are the dq axis current components of the first, second, ..., and Nth three-phase windings of the multi-phase permanent magnet synchronous motor, u dq1 、u dq2 、…、u dqN are the dq axis voltage components of the first, second, ..., Nth three-phase windings of the multi-phase permanent magnet synchronous motor respectively. The average value of the dq axis voltage of each set of three-phase windings is taken as the dq axis equivalent voltage udqequ, and the average value of the dq axis current of each set of three-phase windings is taken as the dq axis equivalent current i dqequ After the dq axis equivalent voltage and current are calculated by formula (3) and formula (4), the optimal current vector angle is obtained after the extreme value search link.

[0056] Figure 3 Figure 3 is a block diagram of a SOGI (Single-Oriented Gate Array) filter. SOGI is a resonant controller that resonates at a specified frequency and outputs two orthogonal signals at the resonant frequency. G(s) exhibits bandpass filter characteristics. At the resonant frequency, the output signal has the same amplitude and phase as the input signal. If the SOGI's resonant frequency is set to the frequency of the high-frequency signal, the high-frequency component in the electromagnetic torque equation can be extracted.

[0057] The above embodiments are merely illustrative of the principles and effects of the present invention, as well as some embodiments of its application. A person skilled in the art may make several modifications and improvements without departing from the inventive concept of the present invention, and all of these modifications and improvements fall within the scope of protection of the present invention.

Claims

1. A high-efficiency control method for a multi-phase permanent magnet synchronous motor, characterized by: The following steps are included Step 1: Construct the equivalent electromagnetic torque model of the multi-phase permanent magnet synchronous motor in the dq axis system: ， in L d is the equivalent d-axis inductance of the motor, L q is the equivalent q-axis inductance of the motor, ψ m is the permanent magnet flux of the motor, i dequ 、 i qequ are the equivalent d-axis current component and equivalent q-axis current component of the motor respectively, P n is the number of motor pole pairs; According to the dq axis current of each set of three-phase windings, the equivalent dq axis current components of the multi-phase permanent magnet synchronous motor are obtained: ， in i dq1 、 i dq2 、…、 i dqN are the dq axis current components of the first, second, ..., Nth three-phase windings of the multi-phase permanent magnet synchronous motor respectively; Step 2: Superimpose a virtual high-frequency signal on the current vector angle to construct an equivalent electromagnetic torque model of the multi-phase permanent magnet synchronous motor after superimposing the high-frequency disturbance signal: ， in T e h represents the electromagnetic torque, i d h 、 i q h are the equivalent d-axis and q-axis current components after the high-frequency disturbance signal is superimposed on the current vector angle; Step 3: Design the extreme value search process: Step 3.1, electromagnetic torque T e h After being processed by bandpass filter, the high-frequency components in the electromagnetic torque are extracted; Step 3.2, the high frequency electromagnetic torque component is compared with sin(ω h t) After multiplication, the DC component is obtained by low-pass filter processing; Step 3.3: Design the integration link to integrate the DC component to obtain the current vector angle; Step 4: Search for the optimal current vector angle by detecting whether the partial differential of the electromagnetic torque term with respect to the current vector angle term is zero.

2. The high-efficiency control method for a multi-phase permanent magnet synchronous motor according to claim 1, characterized in that: The high-frequency signal superimposed on the electromagnetic torque of the motor in step 2 is: ， in I s is the current vector magnitude, A mag is the amplitude of the high-frequency disturbance signal, ω h is the frequency of the high-frequency disturbance signal.

3. A high-efficiency control method for a multi-phase permanent magnet synchronous motor according to claim 1 or 2, characterized in that: The transfer function of the bandpass filter in step 3.1 is: ， in ω f Represents the resonant frequency of the bandpass filter, take ω f = ω h .

4. The high-efficiency control method for a multi-phase permanent magnet synchronous motor according to claim 3, characterized in that: The cutoff frequency of the low-pass filter in step 3.2 is (1 / 10) ω h .

5. The high-efficiency control method for a multi-phase permanent magnet synchronous motor according to claim 1, 2, 3 or 4, characterized in that: According to the optimal current vector angle, the reference current amplitude calculated by the speed outer loop is decomposed to obtain the reference value of the dq-axis current inner loop, realizing efficient control of the multi-phase permanent magnet synchronous motor.

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