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A soft switching quasi-parallel resonant DC-link (QPRDCL) inverter with improved PWM capability has been recently presented. The circuit has the minimum voltage stress of the devices and provides the flexibility of selecting the on/off instants of the resonant link, resulting in improved PWM capability. In this paper, the operational principles and the detailed analysis of the QPRDCL inverter are presented for the resonant components design and the inverter control. An SVPWM with optimal vector sequence suitable for the QPRDCL inverter is also presented through the comparisons among five different modified space vector PWM (SVPWM) techniques classified by the voltage vector sequences. The performance of the selected optimal SVPWM is verified by the experimental results.

Comparative studies between harmonic elimination and optimal PWM strategies are given for high power three-level inverter feeding an induction motor. An effective PWM map construction method based on the valid region on the frequency modulation index plane is suggested. Thereby, an optimal map including asynchronous space vector PWM, harmonic elimination and optimal PWM method is generated covering all of the low, middle and high modulation index regions. The PWM map was designed for 1 MVA rated general purpose GTO inverter and implemented with a digital signal processor. Experimental results are presented for 10 kVA prototype. >

A recently proposed circuit P-Q transformation is used to analyze a three-phase controlled-current PWM rectifier. The DC operating point and AC transfer functions are completely determined. Most features of the power converter are clearly interpreted. They are: (1) the output voltage can be controlled from zero to maximum; (2) the system is equivalently an ideal current source in the steady state; (3) the system can be described as linear circuits; and (4) the input power factor can be arbitrarily controlled within a certain control range. >

A new control scheme named optimum quantum sequence control (OQSC) which always minimizes the output voltage ripple of the quantum series resonant converter (QSRC) for all possible sequences is proposed. This control scheme is so general that it is irrelevant to all circuit conditions such as magnitudes of circuit elements as well as input/output voltage so far as it is operating in the continuous conduction mode (CCM). Furthermore, the dynamic range of QSRC is much extended by the OQSC. This feature is verified by simulations and experiments with good agreements. >

For the generalization of quantum resonant converters, new quantum resonant modules, which are a quantum series resonant module (QSRM) and a quantum parallel resonant module (QPRM), are proposed. The QSRM and QPRM are modeled as an equivalent inductor and an equivalent capacitor, respectively. The models of the proposed modules are useful in deriving the practical family of quantum resonant converters corresponding to the conventional PWM converters. The AC/AC quantum resonant converters are useful in high-performance applications. The concept of modules and the validity of the modeling are confirmed by the experiment. >