Quasi Fixed-frequency Control Scheme For Actively Clamp Resonant DC-link Inverter Based On Two Amplitude Technology

In this paper,A novel quasi Fixed-frequency Control scheme for the actively clamped dc-link inverter (ACRDCLI) based on two amplitude control technology is presented. The bus voltage of ACRDCLI resonates down to zero periodically, so that the inverter switches can commutate at the point of zero bus voltage. Since all switches have to switch on and off at a discrete time, DPM control mode is the only feasible use option. However,the ACRDCLI has a continuous output spectrum with a rich low frequency portion in this control scheme, it is impossible to realize the fixed-frequency control.Luckily,ACRDCLI can realize quasi Fixed-frequency Control based on Two amplitude technology, which is adopted the PWM control techonlogy. The proposed scheme has the advantage of a high system efficiency, dynamic performance and output waveform precision.This paper first analysis the frequency conversion characteristics of DPM,and it makes a contrast of the output-wave spectrum which used PWM and DPM control scheme.Then it introduces the main fixed-frequency characteristics of PWM control techonlogy and the applicability to ACRDCLI.The proposed control scheme for the ACRDCLI which is compared to the conventional DPM control scheme exhibits the following advantages: (a) It keeps soft-switching conditions for all switches and has simple topology; (b) The import of the two-amplitude dc-link control make it possible that the dc link oscillation frequency increases up to 500 kHz, which greatly improves the control precision; (c) The switching frequency is constant, so that an optimized output spectrum is obtained, which reduces the volume of output filter, improves both dynamic and static output performance; (d) The decoupled design of dc-link and inverter control has the flexibility of using various PWM control scheme to the inverter; (e) It could potentially be applied to UPS, aerospace power, Motor Drivers, Active Power Filter, and many other applications.In this paper a 3KW PWM full-bridge ACRDCLI is designed with the proposed control scheme. EPM7032SLC44 is used to achieve high speed logic design for the dc-link and TMS320F2812 is used to achieve dual-loop inverter control. System operation principle is given in detail. To verify the results, a comparison of the output spectrum between PWM and DPM control scheme is given. Simulative and Experimental results confirm the analysis.The research of the paper is supported by National Science Foundation of Zhejiang Province(No.Y105344).