Variable weight superposition type overmodulation method for electric vehicle motor controller

Abstract

The invention discloses a variable weight superposition type overmodulation method for an electric vehicle motor controller and belongs to the technical field of modulation. The method comprises the following steps of: calculating to obtain a modulation coefficient by adopting a magnetic field orientation method; obtaining an initial value of a superposition weight factor; according to a target voltage vector, calculating to obtain a phase angle of the target voltage vector in a static coordinate system; carrying out optimization calculation to obtain a superposition weight factor optimization value; according to the phase angle of the target voltage vector under the static coordinate system, calculating to obtain a weighted component used for superposition, and obtain a reference voltage vector; and according to the reference voltage vector and a space vector pulse width modulation method, calculating to obtain a switching control signal of an inverter. According to the method, the superposition weight factor is optimized and calculated according to the phase angle of the target voltage vector, so that the phase current harmonic distortion rate of a motor and the torque ripple of a driving system are effectively reduced, and the power output performance of an electric vehicle and the comfort of a driver and passengers are improved.

Description

technical field [0001] The invention relates to the technical field of modulation, in particular to a variable weight superposition overmodulation method used for a motor controller of an electric vehicle. Background technique [0002] The new energy vehicle motor controller usually uses the space vector pulse width modulation method (SVPWM) to calculate the control signal of the inverter IGBT switch to realize the torque control of the drive system. The theoretical operating region of the motor controller includes the linear modulation region as well as the non-linear overmodulation region. The working area of ​​the traditional motor drive system is limited to the linear modulation area and the shallow non-linear over-modulation area, which does not make full use of the voltage output capability of the controller, resulting in low voltage utilization. When the controller works in the deep nonlinear overmodulation region, there will be a sudden change in the phase angle of ...

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Problems solved by technology

The working area of ​​the traditional motor drive system is limited to the linear modulation area and the shallow non-linear over-modulation area, which does not make full use of the voltage output capability of the controller, resulting in low voltage utilization

When the controller works in the deep nonlinear overmodulation region, there will be a sudden change in the phase angle of the voltage vector, which will cause a sharp increase in the harmonic distortion rate of the phase current, resulting in torque ripple in the motor drive system, affecting the power output performance of new energy vehicles and The comfort of the driver and passengers, the traditional overmodulation algorithm has not made targeted optimization for this

The existing electric drive systems of new energy vehicles mainly have the following disadvantages: most of them cannot operate in the deep over-modulation region, and the voltage utilization rate is low; some electric drive systems with over-modulation algorithms use theoretical calculation methods, which have a large amount of calculation and are not applicable For engineering applications; some overmodulation algorithms use the weight superposition calculation method to reduce the calculation amount of the algorithm, but when the voltage vector crosses the center line of the modulation sector, there will be a sudden change in the phase angle of the voltage vector, which will cause a sharp increase in the harmonic distortion rate of the phase current, resulting in a The problem of torque ripple in the drive system affects the power output performance of new energy vehicles and the comfort of drivers and passengers

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