Inverter 12-sector virtual vector overmodulation strategy

Abstract

The invention relates to the field of inverter modulation, in particular to an inverter 12-sector virtual vector overmodulation strategy. This strategy selects the corresponding virtual voltage vector to synthesize the reference voltage vector through 12-sector judgment. The modulation range of the algorithm is improved through the over-modulation technology, the over-modulation process is smooth, and the amplitude of the fundamental wave of the output voltage is not lost, which effectively enhances the applicability of the algorithm.

Description

technical field [0001] The invention relates to the field of inverter modulation, in particular to an inverter 12-sector virtual vector overmodulation strategy. Background technique [0002] The three-phase voltage source inverter using pulse width modulation technology (PWM) is widely used in motor drive systems due to its simple control algorithm, high output quality, and good stability. While improving the output waveform performance, the PWM inverter also brings problems such as shaft voltage, bearing current and electromagnetic interference, shortening the service life of the motor and affecting the normal operation of other electronic equipment. Existing studies have proved that the zero-sequence component (ie, common-mode voltage) in the output voltage of the PWM inverter is the main cause of these negative effects. With the development of inverters towards high power and high frequency, the problem of common mode voltage is also aggravated with the increase of switc...

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Problems solved by technology

[0006] 1. Although the adjacent state synthesis method reported in Reference 1 avoids the use of zero vectors to participate in the synthesis and effectively reduces the common-mode voltage amplitude of the inverter output, the modulation range has relatively large limitations and cannot control the common-mode voltage. The third harmonic component in the middle brings difficulties to the design of common mode filters

[0007] 2. The virtual voltage vector method reported in reference 2 can suppress both the common-mode voltage amplitude and the third harmonic component, but it needs to rotate the coordinate axis by 30 degrees. The traditional 6-sector discrimination method is used, and the sector judgment is complicated without highlighting the virtual The innovation of the voltage vector, and at the same time, the modulation degree is reduced to 0-0.7854 in order to suppress the third harmonic component, and the practical application is limited

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