PWM (Pulse Width Modulation) pulse width dynamic adjustment and neutral-point balance method based on current observer

Abstract

The invention relates to a PWM pulse width dynamic adjustment and neutral point balance method based on a current observer, and the method is technically characterized in that a current fundamental component is extracted through current observation, the dynamic adjustment time and the steady-state adjustment voltage are calculated, the adjustment output level time is calculated through neutral point balance, and the adjustment output level time and the dynamic adjustment time are input to the pulse width adjustment to complete the adjustment of the PWM pulse width. The problems that PWM response lags behind in existing conventional table look-up control, current coupling and disorder exist in the adjusting process, harmonic waves are increased and the like are solved, the advantage that the current harmonic waves of an optimized PWM table look-up method are low is reserved, meanwhile, the defect of an existing neutral-point balance technology is overcome, the limitation that common-mode component adjustment must be used is broken through, and the problems of insufficient adjustment capability and poor real-time performance caused by limitation of zero-sequence voltage adjustment in an existing method are solved.

Description

technical field [0001] The invention belongs to the field of PWM pulse width modulation, in particular to the dynamic adjustment of PWM pulse width based on a current observer and its midpoint balance method. Background technique [0002] At present, the domestically developed three-level inverters have begun to be put into industrial applications, but compared with similar foreign inverters, there is a problem that the maximum output power is low. Reducing the PWM switching frequency is one of the effective ways to increase the output power of the inverter, but when the ratio of the switching frequency to the output fundamental frequency is low, the output current waveform pulsation and harmonics are large under asynchronous PWM, and the corresponding torque pulsation is large, while optimizing the PWM When the look-up table method is used in vector control with low switching frequency, there are problems such as response lag, current disorder, and the system is difficult t...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art, propose the PWM pulse width dynamic adjustment and midpoint balance method based on the current observer, solve the PWM response hysteresis in the existing conventional look-up table control, current coupling, disorder and harmonic in the adjustment process At the same time, it overcomes the defects of the existing midpoint balance technology, breaks through the limitation that the common mode component must be used for adjustment, and solves the problems of insufficient adjustment ability and poor real-time performance due to the limited zero-sequence voltage adjustment.

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