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A shifted space vector pulsewidth modulation (PWM) (SVPWM) method to control dc-link resonant inverters is presented in this paper. The shifted SVPWM has the same effective vectors and operation time as the traditional SVPWM in all six space sectors, while the sequences of vectors changed according to the load current flow direction. All the switches of a three-phase inverter can be turned on under the zero-voltage switching condition, and only one auxiliary resonance during one PWM switch period of the inverter is required. The aims of the method are to increase the switching frequency of the inverter, reduce the switching frequency of the dc-link resonant circuit, and improve the utility of the dc-link voltage. A set of design rules to generate the shifted SVPWM, as well as its hardware implementation, is described in detail. The synchronization circuit is also discussed. To decrease the time burden of the digital signal processor, a field-programmable gate array is employed to receive the effective vectors and the corresponding time and generates the shifted SVPWM drive signals. The simulation and experimental results have verified the feasibility of the shifted SVPWM approach.
Date of Publication: Sept. 2012