Time-Frequency Analysis of the Delta Modulation and PWM Control for the Asynchronous Motors

Abstract

This work presents some considerations on a control method for a three-phase asynchronous motor and a time-frequency analysis of the proposed system. The control method uses the delta modulation principle to generate the command signals for a full bridge power inverter that drives three phase asynchronous motor. The time-frequency analysis can bring more new information that could be used to develop new control strategies. The operation principle and the analysis and simulation results are also presented to compare the performances of this control method versus a direct feed from mains.

Brush-DC equivalent control based delta modulation for a PWM inverter-fed nine phase induction machine drive

“…In most delta modulation applications, the input reference signal to the delta modulator is a sinusoidal waveform [49]- [51], [56], [57]. The use of sinusoidal modulating signals causes limited input voltage transfer and the voltage transfer of a sinusoidal modulating signal is at most 87% [47], [58].…”

“…The other benefits of using delta modulation in PWM inverters are that it allows smooth transition from the PWM mode to the constant pulse mode and has inherent lower order harmonic attenuation because of the filter in the feedback loop. The delta modulator was first proposed in [47], presented in [50] for software implementation and analysed in [56]- [57] forming the basis for its use in variable speed drives. The other alternative current controllers popularly used in PWM inverters are the PI controller and the hysteresis controller presented in detail in Appendix B.…”