A hybrid magnetic circuit permanent magnet synchronous motor for electric vehicles and its driving method

Abstract

The disclosure provides a hybrid magnetic circuit permanent magnet synchronous motor for an electric vehicle and a driving method thereof, including a radial stator, an axial winding, a radial winding and a solid rotor, and the coaxially connected two-stage rotor is built in two The radial stator is placed coaxially with the radial stator, the axial winding is placed concentrically in the middle of the two-section rotor and divides the rotor into two in the axial direction, and the permanent magnet is placed in the rotor to generate radial magnetic poles and axial magnetic poles. Part of the magnetic flux generated by the permanent magnets enters the radial stator through the radial poles and interlinks with the radial armature windings to form the radial main flux; the other part interlinks with the axial armature windings through the axial poles to form the axial main flux. The magnetic flux finally returns to the permanent magnet of the rotor on the other side, and the radial main magnetic flux is connected in parallel with the axial main magnetic flux; this disclosure weakens the magnetic flux leakage effect at the end of the motor, improves the material utilization rate, and increases the power Density, and can flexibly realize the field-increasing operation and the field-weakening speed-expanding operation, which broadens the economical operation range of the motor.

Description

technical field [0001] The disclosure belongs to the technical field of permanent magnet synchronous motors, in particular to a hybrid magnetic circuit permanent magnet synchronous motor for electric vehicles and a driving method thereof. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. [0003] Permanent magnet motors are usually divided into four categories: permanent magnet DC motors, asynchronous start permanent magnet synchronous motors, permanent magnet brushless DC motors and speed-adjustable permanent magnet synchronous motors. The structural difference between the permanent magnet DC motor and the ordinary DC motor is that the former cancels the excitation winding and the pole core, and replaces it with a permanent magnet pole. It has the characteristics of simple structure, high reliability, high efficiency, small size and light weight. ...

AI Technical Summary

Problems solved by technology

[0007] 3. In the rotor structure of the existing built-in permanent magnet synchronous motor, the permanent magnets of the rotor are arranged and combined to realize the "magnetism gathering effect", so the magnetic poles of the rotor core have a high magnetic density and a large leakage flux

The rotor leakage flux passes through the end of the motor rotor or the end cover is closed, and because the total magnetic flux generated by the permanent magnet is constant, the existence of the end leakage flux not only makes the magnetic field distribution at the two ends of the motor uneven, but also reduces the Effective flux utilization, which reduces the power density and torque density of the motor

In order to overcome the influence of the leakage flux at the end, in the actual design, the motor rotor often adopts an overhang structure. This structure makes the axial length of the rotor core larger than the axial length of the motor stator core, but this structure significantly increases the axial length of the motor. This further increases the amount of iron core material and manufacturing cost of the motor, and the structure essentially does not play a role in suppressing the leakage flux at the end

[0008] 4. According to the different paths of the d-axis flux during the field-weakening operation of the motor, the rotor structure of the existing built-in permanent magnet motor can be divided into two types: the first type, when the field-weakening control is performed, the d-axis generated by the armature winding The magnetic flux will directly pass through the permanent magnet of the motor, so this structure often causes irreversible demagnetization of the permanent magnet; the second type, when performing field weakening control, the d-axis magnetic flux generated by the armature winding does not directly pass through the permanent magnet, but The excitation magnetic field generated by the d-axis current forces more rotor flux to pass through the end of the motor and the end cover to close. This structure significantly increases the leakage flux of the motor, and the reluctance at the end of the motor is usually larger than that of the air gap. Much more, so the d-axis current required for field weakening is larger, significantly increasing the cost of the motor power inverter and the copper loss of the winding

[0009] 5. The armature back electromotive force harmonic of the existing permanent magnet synchronous motor is relatively large, and the cogging torque problem is prominent, so it often brings serious vibration and noise problems

At present, the method of stator inclined slot or rotor inclined pole is usually used to improve the counter electromotive force harmonic and weaken the cogging torque, but the processing technology of stator inclined slot and rotor inclined pole is more complicated, which greatly increases the manufacturing cost, and will be reduced to a certain extent The average electromagnetic torque of the motor, reducing the torque density and power density of the motor

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