Discrete modeling and control method of dual three-phase induction motors under low switching frequency

Abstract

The invention discloses a discrete modeling and control method for double three-phase induction motors under low switching frequency, and belongs to the field of electricians, motors and power electronics. Aiming at a low switching frequency working condition, the discrete modeling method provided by the invention obtains a motor discrete mathematical model which is more accurate than traditionalEuler discrete modeling by means of Laplace transformation and the like. Meanwhile, the double-winding staggered model predictive control method provided by the invention makes full use of the characteristic of high control freedom degree of the double three-phase induction motors, halves the control delay caused by low switching frequency through the staggered control of the two sets of three-phase windings, reduces the time span of predictive control, effectively improves the control effect, and reduces the switching frequency. According to the positive and negative small vector interleavingcontrol, two inverters are set to preferentially output opposite redundant small vectors, so that the change rate of the midpoint voltage of the bus is reduced, and the switching frequency is furtherreduced.

Description

technical field [0001] The invention relates to the fields of electric engineering, motors and power electronics, in particular to a discrete modeling and control method for a double-three-phase induction motor at a low switching frequency. Background technique [0002] In recent years, in the field of medium-voltage and high-power applications, multi-phase motor multi-level drive systems have attracted more and more attention due to their advantages such as low stress on power devices, high reliability, high power quality, and easy operation at low switching frequencies. . Among them, the dual three-phase induction motor can be obtained by rewinding the stator windings of the three-phase squirrel-cage induction motor, which is a good entry point in the field of multi-phase motor drive system research. In a drive system with high power, the switching frequency of the driver is often lower than 1kHz based on the consideration of reducing switching loss and improving heat dis...

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Problems solved by technology

In a drive system with high power, the switching frequency of the driver is often lower than 1kHz based on the consideration of reducing switching loss and improving heat dissipation conditions. However, the existing low switching frequency motor control methods often have the following three problems: First, The low switching frequency enhances the influence of coupling factors in the motor drive system, so that there is a large deviation between the motor discrete model obtained by using Euler discrete in the traditional control method and the real system, which seriously affects the control effect; second, the low switching frequency The frequency will cause a higher control signal delay, and the traditional control method often uses a PI regulator to control the motor, the bandwidth of the system will be reduced, which seriously affects the stability of the control; third, in order to solve the bandwidth problem caused by the PI regulator, The model predictive control method has attracted widespread attention, but in order to obtain a good control effect, the traditional model predictive control method often requires a large amount of calculation, which puts forward high requirements on the performance of the controller, which is not conducive to practical application

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