Permanent magnet synchronous motor structure suitable for vehicle-driven high-speed operation and control method

Abstract

The invention discloses a permanent magnet synchronous motor structure suitable for vehicle-driven high-speed operation and a control method. The permanent magnet synchronous motor structure comprises a rotor structure capable of counteracting part of direct-axis magnetic flux when a permanent magnet synchronous motor operates at a high speed, and a method for realizing speed self-adaptive operation by controlling the current phase of a motor stator under the condition that the input voltage is not changed. The method has the beneficial effects that the running power of the motor of the new energy automobile in the high-speed stage is reasonably controlled, and the problem that the endurance mileage is greatly shortened when the new energy automobile runs at a high speed is remarkably solved.

Description

Technical Field

[0001] The present invention belongs to the field of permanent magnet synchronous motor structure and control, and in particular relates to a permanent magnet synchronous motor structure and a control method suitable for high-speed vehicle driving. Background Art

[0002] With the increasing attention paid to environmental protection and sustainable development around the world, new energy vehicles, as a green travel mode, are gradually becoming a development trend in the automotive industry. Compared with traditional energy vehicles, new energy vehicles are popular among consumers for their low energy costs and comfortable driving experience. Permanent magnet synchronous motors are widely used in new energy vehicles for their high efficiency, energy saving, high reliability, low noise and light weight. However, in more and more applications, new energy vehicles still have shortcomings in the high-speed operation stage, and there is a general problem that the cruising range will be greatly shortened in the high-speed operation stage. At its root, the main reason is that the power cannot be reasonably controlled in the high-speed operation stage, resulting in a significant increase in energy consumption. Therefore, how to control the power of new energy vehicles in the high-speed operation stage and maintain their cruising range in the high-speed operation stage has become a technical problem that needs to be solved urgently. Summary of the invention

[0003] Technical issues

[0004] The current rated range of new energy vehicles is quite impressive, but there is a common problem that the range will be greatly shortened at high speeds. The reason is that the motor power of new energy vehicles at high speeds cannot be reasonably controlled. Therefore, how to reasonably control the motor power of new energy vehicles at high speeds and maintain their range at high speeds has become an urgent issue.

[0005] Technical Solution

[0006] In order to solve the above problems, the purpose of the present invention is to provide a permanent magnet synchronous motor structure and control method suitable for high-speed operation of a vehicle drive, which improves the problem of a significant reduction in the cruising range of new energy vehicles during the high-speed operation stage, effectively controls the motor power in the high-speed stage, and reduces energy consumption. The permanent magnet synchronous motor structure and control method suitable for high-speed operation of a vehicle drive include: a rotor structure that can offset part of the direct-axis magnetic flux when the permanent magnet synchronous motor is running at high speed, and a method for achieving speed adaptive operation by controlling the motor stator current phase under the condition that the input voltage remains unchanged.

[0007] The rotor structure capable of offsetting part of the direct-axis magnetic flux when the permanent magnet synchronous motor runs at high speed is characterized in that the permanent magnet synchronous motor adopts a tangentially excited rotor, the permanent magnets in the rotor are installed in an embedded manner, the tangential size of the permanent magnets in the rotor is smaller than the radial size, and the direct-axis magnetic resistance of the motor is smaller than the quadrature-axis magnetic resistance.

[0008] Furthermore, a magnetic isolation sleeve is installed between the permanent magnet of the permanent magnet synchronous motor and the inner shaft hole of the rotor, close to the inner shaft hole of the rotor.

[0009] Furthermore, the distance between the permanent magnet and the inner shaft hole of the rotor is the minimum distance that meets the mechanical strength requirement of the rotor.

[0010] Furthermore, the phase of the stator current of the permanent magnet synchronous motor leads the rotor excitation voltage, and the phase of the armature reaction flux leads the stator magnetomotive force.

[0011] The method for realizing speed adaptive operation by controlling the motor stator current phase under the condition of constant input voltage is characterized in that when the actual motor speed reaches the rated speed, the motor stator current phase is controlled to generate a direct axis current component i on the direct axis for offsetting part of the direct axis magnetic flux. d , during the motor control process, the direct axis current i d With the quadrature axis current i q The value satisfies the constraint and Among them I ed is the effective value of the rated phase current of the motor, L q is the quadrature-axis inductance, L d is the direct axis inductance, Ψ0 is the rotor excitation flux, U ed is the effective value of the rated phase voltage of the motor, w r is the angular velocity of the motor rotor.

[0012] Furthermore, under the premise of keeping the input voltage unchanged, when the actual speed of the permanent magnet synchronous motor reaches the rated speed, the motor stator current phase is controlled to generate a direct axis current component i on the direct axis to offset part of the direct axis magnetic flux of the motor. d ,During the motor control process, the speed of the permanent magnet synchronous motor increases, ,the torque decreases, and the motor operating power remains unchanged.

[0013] Beneficial Effects

[0014] The present invention provides a rotor structure capable of offsetting part of the direct-axis magnetic flux when a permanent magnet synchronous motor is running at high speed, and a method for realizing speed adaptive operation by controlling the phase of the motor stator current under the condition of constant input voltage. A permanent magnet synchronous motor with a rotor structure that meets the requirements is selected. By controlling the phase of the motor stator current, the motor can continue to increase the speed and reduce the torque after the actual speed of the motor reaches the rated speed under the condition of constant input voltage, thereby realizing constant power speed regulation and reasonably controlling the operating power of the motor in the high-speed stage.

[0015] The present invention provides a permanent magnet synchronous motor structure and control method suitable for high-speed vehicle driving. The method significantly improves the problem of greatly shortened driving range of new energy vehicles when driving at high speeds, and reasonably controls the operating power of the new energy vehicle motor in the high-speed stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the magnetic circuit diagram of the permanent magnet synchronous motor rotor.

[0017] Figure 2 This is the electrical characteristics diagram of permanent magnet synchronous motor.

[0018] Figure 3 This is the stator current limiting condition diagram of permanent magnet synchronous motor.

[0019] Figure 4 This is the structural diagram of the three-phase permanent magnet synchronous motor AC servo system. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific 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.

[0021] The present invention provides a permanent magnet synchronous motor structure and control method suitable for high-speed vehicle driving, including a rotor structure capable of offsetting part of the direct-axis magnetic flux when the permanent magnet synchronous motor is running at high speed, and a method for achieving speed adaptive operation by controlling the motor stator current phase under the condition of unchanged input voltage, aiming to solve the problem of greatly shortened cruising range of new energy vehicles during high-speed operation.

[0022] Figure 1 It is the magnetic circuit of the rotor of the permanent magnet synchronous motor. The permanent magnet synchronous motor adopts a tangential excitation rotor. The permanent magnet in the rotor adopts an embedded installation method. The tangential dimension of the permanent magnet in the rotor is smaller than the radial dimension. The direct axis magnetic resistance of the motor is smaller than the quadrature axis magnetic resistance. A magnetic isolation sleeve is installed between the permanent magnet of the permanent magnet synchronous motor and the inner shaft hole of the rotor, close to the inner shaft hole of the rotor. The distance between the permanent magnet and the inner shaft hole of the rotor is the minimum distance that meets the mechanical strength requirements of the rotor.

[0023] Figure 2 The electrical characteristic diagram of the permanent magnet synchronous motor is shown in Figure 2. The stator current phase of the permanent magnet synchronous motor leads the rotor excitation voltage, and the armature reaction flux phase leads the stator magnetomotive force. Angle α is the lead angle of the armature reaction flux phase relative to the stator magnetomotive force phase, and angle γ is the lead angle of the stator current phase relative to the excitation voltage phase. The stator current is in phase with the stator magnetomotive force.

[0024] Based on the rotor structure capable of offsetting part of the direct-axis magnetic flux when the permanent magnet synchronous motor is running at high speed, the present invention provides a method for realizing speed adaptive operation by controlling the motor stator current phase under the condition of constant input voltage. When the actual motor speed reaches the rated speed, the motor stator current phase is controlled to generate a direct-axis current component i on the direct axis for offsetting part of the direct-axis magnetic flux. d , during the motor control process, the direct axis current i d With the quadrature axis current i q The value satisfies the constraint and Among them I ed is the effective value of the rated phase current of the motor, L q is the quadrature-axis inductance, L d is the direct axis inductance, Ψ0 is the rotor excitation flux, U ed is the effective value of the rated phase voltage of the motor, w r is the motor rotor angular velocity.

[0025] Figure 3 is the stator current limiting condition diagram. It can be considered that f Approximately the excitation current, according to the limiting condition Available in i d -i q Draw a line on the plane with (-i f , 0) is the center, and the major axis is Located in q Coordinate direction, the minor axis is The ellipse is represented by a dotted line in the figure. Available in i d -i q Draw a circle on the plane with (0,0) as the center. In the motor control process, the stator current vector falls within the overlapped area of ​​the ellipse and the circle.

[0026] Under the premise of keeping the input voltage unchanged, when the actual speed of the permanent magnet synchronous motor reaches the rated speed, the motor stator current phase is controlled to generate a direct axis current component i on the direct axis to offset part of the direct axis magnetic flux of the motor. d ,During the motor control process, the speed of the permanent magnet synchronous motor increases, ,the torque decreases, and the motor operating power remains unchanged.

[0027] The embodiments of the present invention and their implementation process are as follows:

[0028] A three-phase permanent magnet synchronous motor is selected. The permanent magnet synchronous motor adopts a tangential excitation rotor. The permanent magnet in the rotor adopts an embedded installation method. The tangential size of the permanent magnet in the rotor is smaller than the radial size. The direct axis magnetic resistance of the motor is smaller than the quadrature axis magnetic resistance. A magnetic isolation sleeve is installed between the permanent magnet of the permanent magnet synchronous motor and the inner shaft hole of the rotor, close to the inner shaft hole of the rotor. The distance between the permanent magnet and the inner shaft hole of the rotor is the minimum distance that meets the mechanical strength requirements of the rotor. It meets the electrical characteristics that the stator current phase leads the rotor excitation voltage, and the armature reaction flux phase leads the stator magnetomotive force.

[0029] Figure 4 The structure of the three-phase permanent magnet synchronous motor AC servo system is shown in Figure 1. PT represents the encoder, ST represents the speed controller, LQ and LD represent the current controllers for controlling the q-axis component and d-axis component of the stator current respectively. The ST output signal can be used as the q-axis component i of the stator current. q * The encoder measures the motor rotor position signal θ and the motor real-time rotor speed w r . Real-time detection of the motor stator phase current i A and i B , after 3 / 2 transformation, the two-phase current i can be obtained α and i B , and then through the rotation transformation of the rotor position signal θ, the actual feedback value i of the q-axis current can be obtained q and the actual feedback value of the d-axis current i d The current controllers LQ and LD perform proportional-integral operations on the q-axis current error and the d-axis current error respectively. Without considering feedback decoupling, the output signal of LQ can be regarded as the component u of the stator voltage vector on the q-axis. q * The output signal of LD is regarded as the component u of the stator voltage vector on the d axis. d * , and then through the inverse rotation transformation of the rotor position signal θ, the component u of the stator voltage vector in the stationary αβ coordinate system can be obtained α * and u β * . Real-time detection of motor rotor speed w r When the actual speed reaches the rated speed, the direct-axis current adjustment value i is input to LD through the flux cancellation control algorithm. d * The SVPWM module generates a pulse signal to drive the three-phase inverter according to the components uα* and uβ* of the stator voltage vector in the stationary αβ coordinate system.

[0030] Based on this motor and servo system structure, speed adaptive operation is achieved by controlling the stator current phase of the motor under the condition of constant input voltage, including:

[0031] When the actual speed of the motor reaches the rated speed, the stator current phase is controlled to generate a direct-axis current component i on the direct axis to offset part of the direct-axis magnetic flux. d , during the motor control process, the direct axis current i d With the quadrature axis current i q The value satisfies the constraint and Among them I ed is the effective value of the rated phase current of the motor, L q is the quadrature-axis inductance, L d is the direct axis inductance, Ψ0 is the rotor excitation flux, U ed is the effective value of the rated phase voltage of the motor, w r is the angular velocity of the motor rotor.

[0032] Under the premise of keeping the input voltage unchanged, when the actual speed of the permanent magnet synchronous motor reaches the rated speed, the motor stator current phase is controlled to generate a direct axis current component i on the direct axis to offset part of the direct axis magnetic flux of the motor. d ,During the motor control process, the speed of the permanent magnet synchronous motor increases, ,the torque decreases, and the motor operating power remains unchanged.

[0033] In summary, the present invention provides a permanent magnet synchronous motor structure and control method suitable for high-speed vehicle driving, using a permanent magnet synchronous motor with a rotor structure that can offset part of the direct-axis magnetic flux when the motor is running at high speed. By controlling the phase of the motor stator current, under the condition that the input voltage remains unchanged, when the actual speed of the motor reaches the rated speed, the speed continues to increase and the torque is reduced. The motor operating power remains unchanged, thereby realizing constant power speed regulation, significantly reducing the energy consumption of the motor in the high-speed stage, and effectively solving the problems existing in the prior art.

[0034] The present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solution of the present invention. The above specific embodiments are merely illustrative and not restrictive. Without departing from the scope of the present invention and the scope of protection of the claims, a person of ordinary skill in the art can also make many forms of specific changes under the guidance of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A permanent magnet synchronous motor structure and control method suitable for high-speed vehicle driving, characterized in that: A rotor structure capable of offsetting part of the direct-axis magnetic flux when a permanent magnet synchronous motor is running at high speed, and a method for achieving speed adaptive operation by controlling the motor stator current phase under the condition of constant input voltage.

2. The rotor structure capable of offsetting part of the direct-axis magnetic flux when the permanent magnet synchronous motor runs at high speed according to claim 1 is characterized in that: The permanent magnet synchronous motor adopts a tangentially excited rotor. The permanent magnets in the rotor are installed in an embedded manner. The tangential size of the permanent magnets in the rotor is smaller than the radial size, and the direct-axis magnetic resistance of the motor is smaller than the quadrature-axis magnetic resistance.

3. The rotor structure capable of offsetting part of the direct-axis magnetic flux when the permanent magnet synchronous motor runs at high speed according to claim 1 or 2, characterized in that: A magnetic isolation sleeve is installed between the permanent magnet of the permanent magnet synchronous motor and the inner shaft hole of the rotor, close to the inner shaft hole side of the rotor.

4. The rotor structure capable of offsetting part of the direct-axis magnetic flux when the permanent magnet synchronous motor runs at high speed according to claim 1 or 2, characterized in that: The distance between the permanent magnet and the inner shaft hole of the rotor is the minimum distance that meets the mechanical strength requirements of the rotor.

5. The rotor structure capable of offsetting part of the direct-axis magnetic flux when the permanent magnet synchronous motor runs at high speed according to claim 1 or 2, characterized in that: The stator current phase of the permanent magnet synchronous motor leads the rotor excitation voltage, and the armature reaction flux phase leads the stator magnetomotive force.

6. The method of achieving speed adaptive operation by controlling the motor stator current phase under the condition of constant input voltage according to claim 1, characterized in that: When the actual speed of the motor reaches the rated speed, the motor stator current phase is controlled to generate a direct axis current component i on the direct axis to offset part of the direct axis flux. d , during the motor control process, the direct axis current i d With the quadrature axis current i q The value satisfies the constraint Among them I ed is the effective value of the rated phase current of the motor, L q is the quadrature-axis inductance, L d is the direct axis inductance, Ψ0 is the rotor excitation flux, U ed is the effective value of the rated phase voltage of the motor, w r is the angular velocity of the motor rotor.

7. The method for realizing speed adaptive operation by controlling the motor stator current phase under the condition of constant input voltage according to claim 1 or 6, characterized in that: Under the premise of keeping the input voltage unchanged, when the actual speed of the permanent magnet synchronous motor reaches the rated speed, the motor stator current phase is controlled to generate a direct axis current component i on the direct axis to offset part of the direct axis magnetic flux of the motor. d ,During the motor control process, the speed of the permanent magnet synchronous motor increases, ,the torque decreases, and the motor operating power remains unchanged.

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