Fast three-phase space vector modulation method based on three-dimensional coordinate system

Abstract

A fast three-phase space vector modulation method based on a three-dimensional coordinate system belongs to the technical field of power electronics. The present invention first utilizes the simple coordinate change to map the vector from the two-dimensional coordinate system to the three-dimensional coordinate system, and then uses three modulation vectors to synthesize the reference voltage vector, and the three modulation vectors form a modulation triangle in the three-dimensional coordinate system, and detect the modulation triangle Detect the modulation vector closest to the origin, calculate the three-phase switch state corresponding to the vector and map it to the three-dimensional coordinate system, scale the reference voltage vector to simplify the multi-level vector space into a two-level vector space; finally calculate the three-phase The duty cycle of the switch state is compared with the triangular carrier wave of the converter to generate the switch drive signal. The invention can realize arbitrary level output only through simple addition and subtraction operations, and has strong expansibility; in addition, the invention provides several controllable factors to improve the performance of various aspects of the multi-level converter.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and relates to a modulation algorithm of a three-phase multilevel converter, especially in the application of modulation algorithms using digital chips such as FPGA and DSP as control chips. Background technique [0002] Space Vector Modulation (SVPWM) is a pulse width modulation method based on the concept of space voltage vector synthesis, which has been widely used in power electronic modulation. Its core idea is to use the different switching states of the converter as the basic action vectors, and synthesize the reference vectors according to the selected basic vectors and their specific action time. Compared with the ordinary PWM modulation algorithm, it has many outstanding advantages: high utilization rate of voltage, easy digital realization, good output waveform quality, close to sinusoidal, reasonable arrangement of space vector, can reduce switching frequency, reduce switchi...

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Problems solved by technology

[0004] Aiming at the inadequacies of the above-mentioned existing SVPWM algorithm that is not easy to expand and cannot completely cancel the multiplication and division and trigonometric function operations, the present invention provides a fast three-phase space vector modulation method based on a three-dimensional coordinate system, which is suitable for three-phase multiple The level converter, the present invention has both the advantages of all the traditional fast SVPWM algorithms and realizes that there is no multiplication, division and trigonometric function operation in the whole modulation process under the three-dimensional coordinate system, and the arbitrary level of the converter is realized by simple addition and subtraction. In addition, the method of the present invention also provides some controllable factors, which can realize the optimization of switching action sequence of various three-phase multilevel converters, reduce switching loss and harmonic output; can eliminate common mode voltage, Output smoother flux linkage and ensure voltage balance within phase and voltage balance between phases

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