Uniform PWM modulation method and system on the basis of natural commutation

Abstract

The invention is suitable for the technical field of electric power, and provides a uniform PWM modulation method on the basis of natural commutation. The method comprises the following steps: a per-unit value of a three-phase modulated wave is calculated; a real-time maximum value and a real-time minimum value of voltage of the three-phase modulated wave are calculated according to the per-unit value; the phase of the three-phase modulated wave shifts for 30 degrees; the real-time maximum value and the real-time minimum value of the three-phase modulated wave after phase shifting are calculated; zero-sequence components under three modulation modes of SPWM, SVPWM and DPWMx are calculated according to the real-time maximum value and the real-time minimum value of the voltage of the three-phase modulated wave before phase shifting and the maximum value and the minimum value of the voltage of the three-phase modulated wave after phase shifting; the zero-sequence components under the three modulation modes of SPWM, SVPWM and DPWMx are super-positioned in the three-phase modulated wave before phase shifting so that a uniform modulated wave signal is acquired; and the uniform modulated wave signal and a carrier wave signal are compared by a controller so that a driving signal for controlling a switch tube is acquired.

Description

technical field [0001] The invention belongs to the technical field of electric power, and in particular relates to a unified PWM modulation method and system based on natural commutation. Background technique [0002] Because the inverter with bidirectional energy flow can realize bidirectional conversion between DC and AC, it is widely used in AC drive, new energy, UPS and other fields. How to control the modulation algorithm of the switching timing of the inverter is the key technology of this device, among which, the carrier-based sinusoidal pulse width modulation (Sinusoidal Pulse Width Modulation, SPWM) and space vector modulation algorithm (Space Vector Pulse Width Modulation, SVPWM) are The two most commonly used modulation techniques, there is also a discontinuous pulse width modulation algorithm (DPWMx, x=0, 1, 2, 3, MAX, MIN) based on carrier modulation introduced in the academic field. [0003] The above various modulation algorithms have their own advantages an...

AI Technical Summary

Problems solved by technology

However, the DPWMx algorithm lacks a specific and simple engineering implementation method

[0007] From the above analysis, it can be concluded that in different fields and working conditions, various PWM modulation algorithms have different advantages and disadvantages. At the same time, the above-mentioned various modulation methods can be switched online without affecting the working stability of the inverter. In this way, it is possible to unify various modulation algorithms

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