Method and system for synchronous modulation of closed-loop base on space vector

Abstract

The invention relates to a method for isochronous modulation of a closed loop based on a space vector. The method comprises the following steps: obtaining reference voltage, voltage Vdc on the direct current side and fundamental wave angular frequency Omegas; calculating a modulation ratio m; calculating an angle Delta Theta passed by the reference voltage and an angle Thetam modulated by the reference voltage; calculating an angle outputted by an impulse sequence through the angle Delta Theta passed by the reference voltage, the angle Thetam and the modulation ratio m modulated by the reference voltage; comparing the variation Delta Thetas of the angle Thetas of the fundamental wave angular frequency Omegas with time integral to the angle outputted by the impulse sequence; and outputting the impulse sequence according to comparative results. The method directly takes the angle as a datum, and replaces an amount containing harmonic wave and noise by using a stable quantity, thereby avoiding the reduction of synchronous modulation performance caused by the harmonic wave and the noise in a closed loop system, and ensuring more accurate isochronous modulation.

Description

technical field [0001] The invention relates to the field of synchronous modulation, in particular to a space vector-based closed-loop synchronous modulation method and system. Background technique [0002] Space Vector Pulse Width Modulation (SVPWM, Space Vector Pulse Width Modulation) is a kind of pulse width modulation (PWM, Pulse Width Modulation) obtained based on the control idea of ​​motor flux trajectory tracking. For AC motors, when the stator resistance is ignored, the integral of the motor stator voltage space vector is the motor stator flux linkage space vector. By controlling the voltage vector acting on the motor and the action time of the voltage vector, the magnetic field trajectory of the motor is controlled. The synchronous modulation based on the SVPWM achieves the purpose of reducing current harmonics and torque ripple by controlling the angle of pulse train output. [0003] When the AC motor is under closed-loop control, since the feedback voltage signa...

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Problems solved by technology

The calculation method of the synchronous modulation system of the prior art closed-loop control is cumbersome. It is necessary to convert the angle that the pulse sequence needs to output into time, and the output time of the pulse sequence is controlled by the timer. Since the time period when the timer outputs the optimal pulse sequence , the fundamental angular frequency is constantly changing, and the time period will not be adjusted due to the changing fundamental angular frequency, resulting in a decrease in the performance of synchronous modulation, or even failing to achieve the purpose of synchronous modulation

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