A Modified Algorithm based on the Equal-Areas PWM for the Extend of Linear Operation of a Microprocessor-Controlled PWM-VSI

Fotis Konstantinos Paterakis, D. Nafpaktitis, M. Darwish, Koulouras E. Grigorios


A modified algorithm based on the Equal-Areas PWM (EAPWM) is being presented in order to extend the linear operation of the inverter in the overmodulation region, while improving the voltage output in terms of fundamental harmonic component amplitude and Total Harmonic Distortion (THD). EAPWM provides an alternative to Regular Sampling (RS) PWM and Space Vector PWM (SVPWM) strategies. EAPWM is a direct digital PWM method that uses the equal areas theorem to determine the pulse widths. This method maintains the commutations through a complete fundamental cycle, in contrast to naturally and regular sampling PWM techniques, where switched pulses progressively disappear for values of modulation index M greater than unity. In addition, this algorithm reveals several linear operating regions of controlling the output fundamental. Simulation and experimental work carried out using a single-phase voltage source inverter (VSI), showing less harmonic content is present for the first harmonic cluster at the switching frequency, compared to (RS) PWM and Space Vector PWM (SVPWM) strategies. This method is suitable for robotic applications where online control through a microcontroller is needed to drive rotating type loads such us ac motor drives and stepper motors.


Equal Areas PWM; Modulation Index; Overmodulation; THD; Direct PWM; Motor Drive;

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DOI: http://dx.doi.org/10.21535%2Fijrm.v5i1.983


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