Soft switching pulse-width modulation (PWM) dc-dc full-bridge converter with controlled rectifier on the secondary side of the high-frequency power transformer is presented in this paper. An active secondary switch, including new nondissipative passive energy recovery turn-off snubber on the secondary side and modified PWM control algorithm, provide conditions for zero-voltage and zero-current turn-on and zero-current turn-off of IGBT transistors on the primary side of the high-frequency dc-dc converter. The simple passive energy recovery snubber ensures also zero-voltage turn-off of the transistor on the secondary side of the power transformer. The principle of operation is explained and analyzed and consequently verified on a 2 kW, 50 kHz laboratory model of the converter.

This paper introduces a high-frequency soft-switching pulse-width modulation DC-DC power converter with secondary active rectifier tested as a DC current source for arc welding applications. The soft-switching DC-DC converter consists of a high-frequency full-bridge inverter, high-frequency power transformer, and a controlled output rectifier with new secondary energy recovery turn-off snubber. Circulating currents in the converter are reduced by using active rectifier, and RMS values of the currents in primary and secondary switches are decreased by utilizing a novel control algorithm. The experimental results of a 4.5 kW DC-DC converter working at switching frequency of 100 kHz are presented.

This paper describes a high-frequency soft-switching dc-dc converter with a simple energy recovery capacitor snubber on the secondary side. The presented dc-dc full-bridge converter with the energy recovery snubber removes the main drawbacks of the classic Phase Shifted PWM (PS-PWM) dc-dc converter, e.g., the circulating current flowing during the free-wheeling interval and dependency of the soft switching on the load current. The converter utilizes a full-bridge topology with pulse-width modulation and a centre-tapped full-wave controlled rectifier with one active switch. The zero-voltage switching on the primary side is ensured by utilising only the magnetizing current of the high-frequency transformer, and thus is load-independent. The proposed energy recovery snubber is described in detailed time waveforms of the converter and verified by simulation. The control algorithm also removes the circulating current, which is typical for PS-PWM converters. The soft-switching of the secondary side transistor is achieved by a simple capacitor snubber with an energy-recovery circuit connected to the output of the dc-dc converter. The principle of operation is verified by measurements on a 2 kW, 50 kHz laboratory model of the proposed dc-dc converter.

This paper presents a grid-tied cascade H-bridge inverter with predictive current control technique. The proposed 15-level cascade inverter consists of three H-bridge inverters with separated DC sources. At the output of the cascade inverter an L filter is used as a grid filter. The cascade inverter is controlled by the mean of RT-Lab. The predictive current regulator and one-phase synchronous reference frame PLL are designed with help of Rapid Control Prototyping. The proposed control method uses a discrete model of the system to predict behavior of the system for each of 15 voltage levels of inverter’s output voltage. Verification by simulation and on a laboratory model is described.

The paper describes and compares the dynamic performance of the PI and the MPC controllers used with the one-phase multilevel cascade inverter connected to the grid through an LCL filter. The cascade inverter uses multilevel sinusoidal PWM modulation technique and is controlled in rotating reference frame. The PI controller uses active damping using virtual resistance to damp oscillations of LCL filter. The MPC controller results present its ability to stabilise unstable plants and no additional active damping technique is necessary to stabilise the LCL filter. Both controllers have the same sampling time. DOI: http://dx.doi.org/10.5755/j01.eee.20.6.7266