A Space Voltage Vector Modulation Method for Multiphase Inverters

Abstract

The invention relates to a novel space voltage vector modulation method for a multi-phase inverter. The method is characterized by dividing each sub-plane into S kinds of sectors according to controlrequirements, and determining m linearly independent basic voltage vectors selected under each condition; carrying out calculating to obtain m expected voltages in each digital control period according to n-phase current on an n-phase motor, electric angle velocity, bus voltage and digital control periods, and expressing the m expected voltages in a vector form; calculating the angle of a synthesized expected voltage vector of each sub-plane in a corresponding plane, and judging the sector where the synthesized expected voltage vector is located and met sector division conditions; selecting mlinearly independent basic voltage vectors, calculating the action time in synthesizing the m linearly independent basic voltage vectors into m expected voltage vectors, and replacing the voltage vector whose action time ti is smaller than 0 with the voltage vector in the opposite direction; and converting the finally output m linearly independent basic voltage vectors and the action time thereofinto duty ratio Dx, outputting the duty ratio Dx to each bridge arm of the n-phase voltage source inverter, and driving the multi-phase motor.

Description

technical field [0001] The invention relates to a multiphase inverter space voltage vector modulation method. Background technique [0002] Multiphase motors have the characteristics of small torque ripple, high reliability, good fault tolerance, and large capacity. They are widely used in low-voltage and high-power applications such as electric vehicles, aviation equipment, and rail transit. The research on their control methods has attracted much attention. The control method determines the output of the multi-phase inverter, and then drives the multi-phase motor to run stably. [0003] Different polyphase motors have different constant power transformation matrices. The constant power transformation matrix decouples and transforms the mathematical model in the natural coordinate system of the polyphase motor to the static Cartesian coordinate system, and decouples the fundamental and harmonic decoupling transformation of the polyphase motor into Multiple sub-planes are c...

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Problems solved by technology

[0005] At present, the existing multi-phase inverter space voltage vector modulation methods are basically divided into two categories: the first category is the method of selecting a single basic voltage vector in a control cycle, which has the problem of not being able to accurately synthesize the desired voltage vector, making The control effect of multi-phase motors is poor. The second type is the method of selecting multiple basic voltage vectors in one control cycle to synthesize the desired voltage vector, which is only applicable to the case where the desired voltage of the harmonic plane is 0, and requires the sub-plane The basic voltage vector distribution conforms to the specific case

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