Overmodulation control method and device for motor

Abstract

The invention discloses an overmodulation control method for a motor, and relates to a motor modulation technology. The overmodulation control method comprises the following steps of: collecting errorsignals and current feedback signals of a motor feedback rotation speed and a given rotation speed, performing conversion from coordinates of a two-phase rotating coordinate system to coordinates ofa two-phase static coordinate system to obtain command voltage signals U[alpha]* and U[beta]* of the motor, performing SVPWM (Space Vector Pulse Width Modulation) to obtain a binary function F([theta]h, [theta]r) of an angle pair ([theta]h, [theta]r) to obtain a modulation ratio MI and calculate the modulation ratio MI, wherein the modulation ratio MI is in one-to-one correspondence with the anglepair ([theta]h, [theta]r); according to the value of the modulation ratio MI, obtaining a value of the angle pair ([theta]h, [theta]r); and according to the value of the angle pair ([theta]h, [theta]r), calculating a voltage vector required by the motor and a corresponding duty cycle to obtain six-path drive signals of an inverter. The overmodulation control method for a motor only needs to obtain value information of the angle pair ([theta]h, [theta]r) to determine the size of a fundamental wave to be output so as to achieve overmodulation, and therefore, the principle is simple, and the operation is convenient.

Description

technical field [0001] The invention relates to motor modulation technology, in particular to a motor over-modulation control method and device thereof. Background technique [0002] Generally, the output voltage of the inverter is limited by the DC bus voltage. Under the condition of constant bus voltage, its utilization rate will affect the torque and power output of the motor in the field weakening area. For example, in the drive system of electric vehicles, usually DC The bus voltage is not high, and because of the internal resistance of the power supply, the DC bus voltage will decrease with the increase of the output power. This situation is very unfavorable for the high power output of the motor under high-speed magnetic field weakening. The reasonable use of the overmodulation algorithm can improve the utilization rate of the DC voltage and expand the stable operating range of the motor. [0003] In the two-level three-phase inverter system, the regular hexagonal ar...

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Problems solved by technology

But it will also bring some problems, the current harmonic content becomes larger, the torque ripple and noise are large, etc.

At the same time, the traditional Holtz dual-mode overmodulation has defects such as not being able to make the output fundamental wave voltage exactly equal to the required fundamental wave value, and lacking strict theoretical proofs.

However, when the traditional Bolognani single-mode overmodulation is at the same modulation depth, the output harmonics are larger

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