A high-efficiency control method for a multi-operation-mode permanent magnet motor with a wide speed range

Abstract

The present invention discloses a wide speed range and high efficiency control method for a multi-operation mode permanent magnet motor. The method constructs a mathematical model in a dq coordinate system, takes the torque equation as the constraint condition of the Lagrange multiplier method, takes the minimum copper loss during motor operation as the objective function to establish the Lagrange equation, solves the relationship between the dq currents of the main drive and the auxiliary drive, and converts the speed loop error e into a fixed value. n The total current after PI output I total The solution obtained by combining the d-axis current relationship between the main drive and the auxiliary drive is used as the current distribution criterion in the motor's high torque mode. The d-axis weak magnetic current is solved using the multi-operation mode permanent magnet motor limit circle. The weak magnetic operation judgment condition is added and the solved d-axis weak magnetic current is given as the d-axis current in the motor's wide speed range mode. At this time, the q-axis current is given by the total current I total Given the given current distribution in the wide speed range mode, this allows for efficient wide speed range control of a multi-mode permanent magnet motor. This control algorithm is not only simple to control but also universally applicable in industrial product applications.

Description

Technical Field

[0001] The present invention relates to the field of permanent magnet motor control, and in particular to a wide speed range and high-efficiency control method for a multi-operating mode permanent magnet motor, which is applicable to the requirements of aerospace, electric vehicles, ships, etc. for high efficiency and wide speed range. Background Art

[0002] Permanent magnet motors (PMMs) are widely used in industry due to their simple structure, compact size, light weight, and high efficiency. However, they are difficult to adjust the air gap magnetic field and face the risk of permanent magnet demagnetization, limiting their speed regulation range. While electrically excited motors (EMMs) can adjust the air gap magnetic field strength, enabling wide speed regulation, they suffer from lower power density than PMMs. At the end of the last century, hybrid excitation motors, combining the advantages of both PM and EM motors, were proposed and have experienced rapid development in recent years, particularly in multi-mode PMMs with their specialized structures. Compared to traditional single-stator PMMs, multi-mode PMMs offer easier air gap flux adjustment and a wider speed regulation range.

[0003] In order to achieve a wide speed regulation range of a permanent magnet motor with multiple operating modes, weak magnetic control must be used. Early weak magnetic control used the weak magnetic base speed as the judgment standard. If the motor speed is greater than the weak magnetic base speed, the motor enters weak magnetic control. Although this method is simple, it ignores the torque output part of the motor. Using only the weak magnetic base speed as the judgment condition limits the application of this method. Currently, the more common method is the voltage feedback method. The principle is to use the difference between the terminal voltage of the motor and the limiting voltage as the weak magnetic judgment condition. This method takes into account the speed and torque of the motor at the same time, which is reflected in the terminal voltage. However, a feedback is introduced into the system, and the reaction cycle of the system becomes longer in actual applications. In order to retain the advantages of this method, the idea of ​​using the limiting voltage as a comparison is borrowed to convert the judgment condition into the load and critical torque T at the current speed. eA The comparison results form a feedforward control, which is used as the flux weakening control of the present invention. Combined with the principle of minimum copper loss, the current is optimized to achieve high-efficiency control of the permanent magnet motor with multiple operating modes over a wide speed range. Summary of the Invention

[0004] The addition of excitation stator windings to multi-mode permanent magnet motors facilitates air gap magnetic field adjustment, but also increases the motor's control dimensionality. Therefore, current cooperative control is required to achieve current distribution in both the low-speed, high-torque region and the high-speed, field-weakening region. To reduce losses in multi-mode permanent magnet motors, this paper proposes a high-efficiency control method for multi-mode permanent magnet motors over a wide speed range.

[0005] A method for efficiently controlling a permanent magnet motor with multiple operating modes over a wide speed range comprises the following steps:

[0006] Step 1: Based on the multi-mode permanent magnet motor's topology, the motor is divided into two operating modes. In the high-torque mode, the motor has two drives: a main drive consisting of the outer stator and rotor, and an auxiliary drive consisting of the rotor and inner stator. In the wide-speed range mode, the motor retains its main drive, but the inner stator winding serves as the excitation winding to regulate the air gap flux of the main drive. A mathematical model for the multi-mode permanent magnet motor in the dq system is established.

[0007] Step 2: Using the torque equation of the motor in the dq coordinate system as a constraint and minimizing the copper loss of the motor during operation as the goal, establish the Lagrangian function and solve the relationship between the dq currents of the main drive and the auxiliary drive.

[0008] Step 3: Detect the speed of the permanent magnet motor in multiple operating modes as the speed feedback n of the motor back , the given speed n ref With feedback speed n back Compare the motor speed error e n , using PI controller according to the speed error e n The total current Itotal of the permanent magnet motor with multiple operating modes is calculated.

[0009] Step 4: Combine the obtained total current Itotal with the result in step 2 to obtain the relationship between the main drive and auxiliary drive dq currents and the total current Itotal, which is used as the current distribution criterion for the multi-operating mode permanent magnet motor operating in the high torque mode.

[0010] Step 5: When the motor terminal voltage reaches the bus voltage limit, the current of the motor during field weakening operation is analyzed in combination with the voltage limit circle and current limit circle of the multi-operation mode permanent magnet motor, and the d-axis field weakening current is calculated.

[0011] In step 6, based on the results of the motor's field-weakening operating conditions, the appropriate motor operating mode is automatically selected. When the wide speed range mode is selected, the current calculated in step 5 is added to the d-axis current setting, while the q-axis current setting is directly determined by the total current Itotal. This completes the current setting for the multi-mode permanent magnet motor operating in the wide speed range mode. Combined with the current distribution in the high torque mode in step 4, the d- and q-axis current settings are finally completed in the full speed range.

[0012] Furthermore, the mathematical model of the multi-operation mode permanent magnet motor in the dq coordinate system described in step 1 is:

[0013] Voltage equation:

[0014]

[0015] Where: u d0,u q0 ,i d0 ,i q0 ,L d0 ,L q0 ,R s0 They are the dq axis voltage, dq axis current, dq axis inductance of the main drive air gap, and the resistance of the main drive armature winding; u d1 ,u q1 ,i d1 ,i q1 ,L d1 ,L q1 ,R s1 are the dq axis voltage, dq axis current, dq axis inductance of the auxiliary drive air gap, and the resistance of the auxiliary drive armature / excitation winding; ω e is the motor electrical angular velocity.

[0016] Magnetic flux equation:

[0017]

[0018] Among them: d0 ,Ψ q0 ,Ψ d1 ,Ψ q1 They represent the winding flux linkage under the dq axis of the main drive air gap and the auxiliary drive air gap respectively; Ψ pm0 ,Ψ pm1 Represents the permanent magnetic flux linkage of the main drive air gap and the auxiliary drive air gap; Ψ f0 represents the permanent magnet flux equivalent to the main drive air gap when the auxiliary drive current is excited; f(i d1 )=m*i d1 , m is the excitation coefficient of the auxiliary drive to the main drive air gap flux.

[0019] Torque equation:

[0020]

[0021] Where p is the number of pole pairs of the motor.

[0022] Furthermore, in the torque equation, the auxiliary drive excitation current i d1 The effect of reducing the motor terminal voltage is obvious, but the torque provided is very small. In order to simplify the calculation and make the motor control more stable, i d1 =0 control, and since the dq axis inductance of the main drive and auxiliary drive of the multi-mode permanent magnet motor is equal, i d = 0 control can better reduce the loss of the motor and increase the utilization rate of the motor current. In step 2, the Lagrange multiplier method is used to obtain the dq axis current relationship between the main drive and the auxiliary drive, and the solution is as follows:

[0023] Taking the torque equation as its constraint condition and the minimum copper loss of the multi-operation mode permanent magnet motor as the constraint condition, the Lagrange equation L1 is established:

[0024]

[0025] Where λ is the Langrange multiplier, T e is the electromagnetic torque of the motor.

[0026] The solution is:

[0027]

[0028] Furthermore, the total current Itotal in step 4 is solved together with the relationship between the main drive and auxiliary drive q-axis currents to obtain:

[0029]

[0030] Furthermore, in order to maximize the use of auxiliary drive excitation performance, all current is used on the d axis. At this time, i q1 =0, so the auxiliary drive no longer provides torque output. According to the given voltage limit circle and current limit circle equations, solve the weak magnetic current i in step 5. d0 , the solution is as follows:

[0031]

[0032] Among them, U samx0 is the maximum voltage that the inverter can output, I smax0 The maximum current that the inverter or motor main drive can withstand, I smax1 It is the maximum current that the inverter or motor auxiliary drive can withstand.

[0033] The weak magnetic current of the motor main drive is solved as follows:

[0034]

[0035] Furthermore, the weak magnetic field judgment expression in step 6 is as follows:

[0036]

[0037] Among them, T L The load applied to the motor.

[0038] When the load of the motor satisfies the equation in the first line of the logic judgment expression, the multi-operation mode permanent magnet motor selects the high torque mode to operate, otherwise the multi-operation mode permanent magnet motor operates in the wide speed range mode.

[0039] The present invention has the following beneficial effects:

[0040] 1. The present invention draws on the idea of ​​MTPA and applies the Lagrange multiplier method to achieve motor operation based on the principle of minimum copper loss. Compared with the MTPA method for traditional motors, the method for minimizing copper loss in multi-operation mode permanent magnet motors requires twice as many variables to be solved, greatly increasing the difficulty of calculation. The present invention reduces unnecessary variables to be solved through motor characteristic analysis, replaces the common solution using fitting methods, eliminates the inconvenience caused by fitting, reduces the difficulty of solving the results, achieves optimal current distribution under equal torque, and improves the operating efficiency of multi-operation mode permanent magnet motors.

[0041] 2. Compared with the traditional d-axis current weakening method, the weakening magnetic control adopted by the present invention has a larger speed regulation range by combining the excitation current of the multi-operating mode permanent magnet motor and the main drive d-axis current weakening magnetic field. The traditional method ignores the output torque of the motor and only uses the weakening magnetic base speed as the judgment condition for entering the weakening magnetic field. It is only applicable to high-speed and low-torque working conditions. The wide speed range control of the present invention provides a logical expression for entering the weakening magnetic field. In essence, it takes into account the current speed and torque of the multi-operating mode permanent magnet motor. As long as the current working condition meets the weakening magnetic field judgment condition, it will automatically enter the wide speed range mode. Compared with the traditional weakening magnetic field method, the weakening magnetic control adopted by the present invention has a wider range of practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 :Block diagram of high-efficiency control of permanent magnet motor with multiple operating modes over a wide speed range;

[0043] Figure 2 : Schematic diagram of the structure of a multi-operating mode permanent magnet motor;

[0044] Figure 3 : Full speed domain current distribution diagram;

[0045] Figure 4 : Limit circle and weak magnetic field judgment diagram;

[0046] Figure 5 : Current experimental graph under high torque mode;

[0047] Figure 6 : Simulation graph under wide speed range mode; 6(a) is the speed simulation diagram of the multi-operating mode motor; 6(b) is the back EMF simulation diagram of the multi-operating mode permanent magnet motor; 6(c) is the dq current simulation diagram of the multi-operating mode permanent magnet motor. DETAILED DESCRIPTION

[0048] The specific embodiment mainly introduces the full-speed domain control of the permanent magnet motor with multiple operating modes based on the minimum copper loss control. The control block diagram is as follows: Figure 1 The specific implementation and implementation effects of this embodiment will be described in detail below with reference to the accompanying drawings.

[0049] Step 1, divide the multi-operating mode permanent magnet motor into two operating modes according to the topological structure of the multi-operating mode permanent magnet motor. High torque mode: The multi-operating mode permanent magnet motor has two drives, one is the main drive of the multi-operating mode permanent magnet motor composed of the outer stator and the rotor, and the other is the auxiliary drive of the multi-operating mode permanent magnet motor composed of the rotor and the inner stator; Wide speed range mode: The main drive of the multi-operating mode permanent magnet motor is retained, and the inner stator winding is used as the excitation winding at this time to adjust the air gap flux of the main drive. Establish a mathematical model of the multi-operating mode permanent magnet motor under the dq system. The mathematical model of the multi-operating mode permanent magnet motor under the dq system is established as follows:

[0050] Voltage equation:

[0051]

[0052] Where: u d0 ,u q0 ,i d0 ,i q0 ,L d0 ,L q0 ,R s0 They are the dq axis voltage, dq axis current, dq axis inductance of the main drive air gap, and the resistance of the main drive armature winding; u d1 ,u q1 ,i d1 ,i q1 ,L d1 ,L q1 ,R s1 are the dq axis voltage, dq axis current, dq axis inductance of the auxiliary drive air gap, and the resistance of the auxiliary drive armature / excitation winding; ω e is the motor electrical angular velocity.

[0053] Magnetic flux equation:

[0054]

[0055] Among them: d0 ,Ψ q0 ,Ψ d1 ,Ψ q1 They represent the winding flux linkage under the dq axis of the main drive air gap and the auxiliary drive air gap respectively; Ψ pm0 ,Ψ pm1 Represents the permanent magnetic flux linkage of the main drive air gap and the auxiliary drive air gap; Ψ f0 represents the permanent magnet flux equivalent to the main drive air gap when the auxiliary drive current is excited; f(i d1 )=m*i d1 , m is the excitation coefficient of the auxiliary drive to the main drive air gap flux.

[0056] Torque equation:

[0057]

[0058] Where p is the number of pole pairs of the motor.

[0059] Step 2: Taking the torque equation of the motor in the dq coordinate system as the constraint condition and the minimum copper loss of the motor during operation as the goal, establish the Lagrangian function and solve the relationship between the dq current of the main drive and the auxiliary drive. In the torque equation, the auxiliary drive excitation current i d1 The effect of reducing the motor terminal voltage is obvious, but the torque provided is very small. In order to simplify the calculation and make the motor control more stable, i d1 =0 control, and since the dq axis inductance of the main drive and auxiliary drive of the multi-mode permanent magnet motor is equal, i d = 0 control can better reduce the loss of the motor and increase the utilization rate of the motor current. Taking the torque equation as its constraint condition and the minimum copper loss of the multi-operation mode permanent magnet motor as the constraint condition, the Lagrange equation L1 is established:

[0060]

[0061] Where λ is the Langrange multiplier, T e is the electromagnetic torque of the motor.

[0062] The solution is:

[0063]

[0064] Step 3: Detect the speed of the permanent magnet motor in multiple operating modes as the speed feedback n of the motor back , the given speed n ref With feedback speed n back Compare the motor speed error e n , using PI controller according to the speed error e n The total current Itotal of the permanent magnet motor with multiple operating modes is calculated.

[0065] Step 4: Combine the total current Itotal obtained with the result in step 2 to obtain the relationship between the main drive and auxiliary drive dq currents and the total current Itotal, which is used as the current distribution criterion for the multi-operation mode permanent magnet motor operating in the high torque mode. Figure 3 The medium-weak magnetic field judgment operating conditions are shown in the high torque mode.

[0066]

[0067] Step 5: When the motor terminal voltage reaches the bus voltage limit, the voltage limit circle and current limit circle of the multi-operation mode permanent magnet motor are combined, as shown in FIG. Figure 4 As shown. The current of the motor during weak magnetic operation is analyzed. In order to maximize the use of auxiliary drive excitation performance, all the current is used on the d axis. At this time, i q1=0, so the auxiliary drive no longer provides torque output. Use the model formula to calculate the d-axis weak magnetic current, and the solution is as follows:

[0068]

[0069] Among them, U samx0 is the maximum voltage that the inverter can output, I smax0 The maximum current that the inverter or motor main drive can withstand, I smax1 It is the maximum current that the inverter or motor auxiliary drive can withstand.

[0070] The weak magnetic current of the motor main drive is solved as follows:

[0071]

[0072] Step 6: Taking the speed ω1 of the permanent magnet motor in multiple operating modes as an example, according to the load of the motor under the current working condition, combined with the i in the limit circle d0 =0 corresponding torque T ea As a critical condition, Figure 4 When the load at this speed is less than T ea , indicating that the motor terminal voltage has not yet reached the limit voltage, and the high torque mode is adopted; on the contrary, when the load at this speed is greater than T ea , indicating that the motor terminal voltage has reached the limit voltage and the wide speed range mode is adopted. At this time, the main drive D axis current should be given the corresponding weak magnetic current. The logical relationship is as follows:

[0073]

[0074] Among them, T L The load applied to the motor.

[0075] The calculated current in step 5 is added to the d-axis current reference, while the q-axis current reference is directly determined by the total current, Itotal. This completes the current reference for the multi-mode permanent magnet motor operating in wide speed range mode. Combined with the current distribution in high torque mode in step 4, this ultimately completes the d- and q-axis current references in the full speed range, enabling efficient control of the multi-mode permanent magnet motor over a wide speed range.

[0076] Figure 5 The experimental graph of the multi-operation mode permanent magnet motor in high torque mode is given. Figure 5 It can be seen that the main drive q axis current i q0 and auxiliary drive q-axis current i q1 There are numerical values, indicating that the main drive and auxiliary drive of the permanent magnet motor in multiple operating modes output power at the same time, and the current is also distributed according to the principle of minimum copper loss, thereby verifying the correctness of the current distribution algorithm in the high torque mode of the present invention.

[0077] Figure 6 The simulation graph of the permanent magnet motor with multiple operating modes in wide speed range mode is given. In order to better reflect the role of the excitation winding when the motor is running at high speed, the field weakening function of the excitation winding is selected after the main drive field weakening, which can have a better comparison effect. When the motor is running at 100rpm, the i d =0 control, when the motor speed increases to 270rpm, the terminal voltage reaches the limit value of 30V, and the motor enters the weak magnetic state. Since the auxiliary drive d-axis current has not been given at this time, the main drive current is calculated according to the corresponding weak magnetic current calculation formula to obtain the weak magnetic current i d0 =-0.438A, and finally stabilized at 330rpm; then, the auxiliary drive d-axis current of 10A was added. When the speed remained unchanged, the terminal voltage amplitude of the motor dropped to about 23.7V, which was a significant decrease. The terminal voltage of about 6V was reduced. Combined with the wide-speed range mode weak magnetic calculation current method, the motor speed was finally increased to 500rpm. Compared with only the main drive weak magnetic effect, the addition of auxiliary drive weak magnetic effect increased the maximum speed by about 52%. The wide-speed range control method greatly improved the speed operating range of the multi-operating mode permanent magnet motor, which is consistent with the theory. It can be seen from this that the wide-speed range efficient control method for the multi-operating mode permanent magnet motor proposed by the present invention is correct and feasible.

[0078] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0079] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A high-efficiency control method for a permanent magnet motor with multiple operating modes over a wide speed range, characterized in that: The steps include: Step 1: Divide the multi-mode permanent magnet motor into two operating modes according to its topological structure: High torque mode: The multi-mode permanent magnet motor has two drives, one is the main drive of the multi-mode permanent magnet motor composed of the outer stator and rotor, and the other is the auxiliary drive of the multi-mode permanent magnet motor composed of the rotor and inner stator; Wide speed range mode: The main drive of the multi-mode permanent magnet motor is retained, and the inner stator winding is used as the excitation winding to adjust the air gap flux of the main drive, and a mathematical model of the multi-mode permanent magnet motor in the dq system is established; Step 2: Using the motor's torque equation in the dq coordinate system as a constraint and minimizing the motor's copper loss during operation as the goal, establish a Lagrangian function and solve the relationship between the dq currents of the main drive and the auxiliary drive. Step 3: Detect the speed of the permanent magnet motor in multiple operating modes as the speed feedback n of the motor back , the given speed n ref With feedback speed n back Compare the motor speed error e n , using PI controller according to the speed error e n Calculate the total current Itotal of the permanent magnet motor with multiple operating modes; Step 4: Combine the obtained total current Itotal with the result in step 2 to obtain the relationship between the main drive and auxiliary drive dq currents and the total current Itotal, which is used as the current distribution criterion for the multi-operation mode permanent magnet motor operating in the high torque mode; Step 5: When the motor terminal voltage reaches the bus voltage limit, the current of the motor during field weakening operation is analyzed in combination with the voltage limit circle and current limit circle of the multi-operation mode permanent magnet motor, and the d-axis field weakening current is calculated; In step 6, based on the results of the motor's weak magnetic operation condition judgment, the mode suitable for the motor operation is automatically selected. When the wide speed range mode is selected, the calculated current in step 5 is added to the d-axis current setting, and the q-axis current setting is directly given by the total current Itotal. This completes the current setting of the multi-operating mode permanent magnet motor operating in the wide speed range mode. Combined with the current distribution in the high torque mode in step 4, the dq-axis current setting in the full speed range is finally completed.

2. The method for high-efficiency control of a multi-operating-mode permanent magnet motor over a wide speed range according to claim 1, characterized in that: In step 1, the mathematical model of the multi-operating mode permanent magnet motor in the dq coordinate system is: Voltage equation: Where: u d0 ,u q0 ,i d0 ,i q0 ,L d0 ,L q0 ,R s0 They are the d-axis voltage, q-axis voltage, d-axis current, q-axis current, d-axis inductance, q-axis inductance of the main drive air gap, and the resistance of the main drive armature winding; u d1 ,u q1 ,i d1 ,i q1 ,L d1 ,L q1 ,R s1 are the d-axis and q-axis voltages, d-axis and q-axis currents, d-axis and q-axis inductances of the auxiliary drive air gap, and the resistance of the auxiliary drive armature / excitation winding; ω e is the motor electrical angular velocity; Magnetic flux equation: Among them: d0 ,Ψ q0 ,Ψ d1 ,Ψ q1 They represent the winding flux linkage under the dq axis of the main drive air gap and the auxiliary drive air gap respectively; Ψ pm0 ,Ψ pm1 Represents the permanent magnetic flux linkage of the main drive air gap and the auxiliary drive air gap; Ψ f0 represents the permanent magnet flux equivalent to the main drive air gap when the auxiliary drive current is excited; f(i d1 )=m*i d1 , m is the excitation coefficient of the auxiliary drive to the main drive air gap flux; Torque equation: Where p is the number of pole pairs of the motor.

3. The method for high-efficiency control of a multi-operating-mode permanent magnet motor over a wide speed range according to claim 2, characterized in that: In the torque equation, the auxiliary drive excitation current i d1 The effect of reducing the motor terminal voltage is obvious, but the torque provided is very small. In order to simplify the calculation and make the motor control more stable, i d1 =0 control, and since the dq axis inductance of the main drive and auxiliary drive of the multi-mode permanent magnet motor is equal, i d = 0 control can better reduce the loss of the motor and increase the utilization rate of the motor current. In step 2, the Lagrangian function is used to obtain the dq axis current relationship between the main drive and the auxiliary drive as follows: Taking the torque equation as its constraint condition and the minimum copper loss of the multi-operation mode permanent magnet motor as the constraint condition, the Lagrangian function L1 is established: Where λ is the Lagrange multiplier, T e is the electromagnetic torque of the motor, The solution is:

4. The method for high-efficiency control of a multi-operation-mode permanent magnet motor over a wide speed range according to claim 3, characterized in that: Solve the relationship between the total current Itotal in step 4 and the main drive and auxiliary drive q-axis current to obtain:

5. The method for high-efficiency control of a multi-operation-mode permanent magnet motor over a wide speed range according to claim 4, characterized in that: In order to maximize the use of auxiliary drive excitation performance, all the auxiliary drive current is used on the d axis. At this time, i q1 =0, so the auxiliary drive no longer provides torque output. According to the given voltage limit circle and current limit circle equations, solve the weak magnetic current i in step 5. d0 , the solution is as follows: Among them, U samx0 is the maximum voltage that the inverter can output, I smax0 The maximum current that the inverter or motor main drive can withstand, I smax1 The maximum current that the inverter or motor auxiliary drive can withstand; The weak magnetic current of the motor main drive is solved as follows:

6. The method for high-efficiency control of a multi-operation-mode permanent magnet motor over a wide speed range according to claim 5, characterized in that: The motor weak magnetic operation condition judgment expression in step 6 is as follows: Among them, T L The load applied to the motor; When the load of the motor satisfies the equation in the first line of the logic judgment expression, the multi-operation mode permanent magnet motor selects the high torque mode to operate, otherwise the multi-operation mode permanent magnet motor operates in the wide speed range mode.

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