Current-fed Three-phase Research Articles

Partial Series Resonance Pulse Commutated Current-Fed Three-Phase Current Sharing DC–DC Converter: ZCS Analysis, Design, and Experimental Results

A three-inductor current-fed converter leveraging short pulse series resonance to facilitate zero-current switching (ZCS) and voltage clamping of the semiconductor devices is proposed and investigated in detail. The circuit exploits series resonance characteristics during conduction overlap of any two switching signals that naturally reduce the current in outgoing switch to zero accomplishing zero-current turn- off . It succeeds in natural switch voltage clamping eliminating the traditional snubber requirement. Owing to the short resonance period, circulating current through the converter limits the conduction losses particularly at light load, thus improving the light-load efficiency. In addition, current-sharing topology offers reduced current stresses through the primary side devices and simpler gate driving requirements because of common source grounded with power supply. Detailed analysis and design are reported. Experimental results from 1-kW proof-of-concept hardware prototype are established to validate the projected claims and confirm the performance and the efficacy of proposed converter. This concept has been verified in single-phase topologies and first time studied for three-phase current-fed circuit.

Naturally Commutated Current-fed Three-Phase Bidirectional Soft-switching DC–DC Converter With 120° Modulation Technique

A three-phase current-fed full-bridge dual-active bridge bidirectional dc–dc converter is proposed to integrate 48 and 380 V dc buses or energy storage to dc microgrid. 120° plus secondary-side modulation technique is implemented to achieve natural commutation of low-voltage-side current-fed devices and zero voltage switching turn-on of high-voltage-side devices. This eliminates the use of passive/active clamp circuits as used in conventional current-fed topologies to mitigate the voltage-spike across the switches. Soft-switching is attained over entire operating range (200 W to 1 kW). Detailed analysis of proposed modulation scheme is reported and soft-switching conditions are derived. Proposed modulation is compared with the 180° modulation scheme to demonstrate converter performance and efficiency. Experimental results have been illustrated for proof-of-concept to validate the claims. Peak efficiencies of 95.8% and 93.8% are obtained at around half load for 59 and 48 V inputs, respectively.

Impulse Commutated Zero Current Switching Current-fed Three-phase DC/DC Converter

An impulse-commutated current-fed three-phase dc/dc converter is proposed. It is a three-inductor current divider topology that reduces the current stress of the components. The proposed converter attains zero current switching (ZCS) of the semiconductor devices via impulse commutation utilizing the circuit paracitics. The devices' voltage is clamped at Vo/n. Voltage clamping and zero-current commutation of devices are load independent. Load voltage is regulated by employing variablefrequency modulation. The current-fed topology with inherent boost ability simplifies the transformer design by reducing the required turns ratio. Rectifier diodes also commutate with ZCS without ringing and eliminate the need for a secondary snubber. A comprehensive study of the proposed converter together with the experimental results obtained from a laboratory prototype of 1 kW have been presented to validate the claims and to evaluate the converter's performance. The proposed converter is suitable for low-voltage high-current applications requiring high voltage gain. It inherently offers short-circuit protection.

Current-fed three-phase and voltage-fed three-phase active converters with optimum PWM pattern scheme and their performance evaluations

This paper describes a new approach to select the optimum sinewave pulsewidth modulation (PWM) patterns suitable for a large-capacity current-fed active PWM power converter and a practical design procedure to determine circuit constants of a low-pass filter connected to suppress higher line current harmonics flowing into the utility-grid AC power source. A feasible test is implemented by building a prototype 500 kW three-phase current-fed PWM power converter which is designed and controlled on the basis of the proposed considerations. It is verified from a practical point of view that these new conceptual considerations are more effective and acceptable to minimize higher harmonic current components flowing into the utility-grid AC power source. This experimental setup provides highly efficient steady-state characteristics of the current-fed three-phase PWM power converter under the operating condition of a unity power factor correction and sinewave line current shaping schemes. Furthermore, this unique optimum PWM pattern derived from the theoretical method proposed here is conveniently applicable to a voltage-fed three-phase PWM converter. It is verified that this optimum PWM pattern provides excellent switching performance with a lower switching frequency mode than the conventional carrier-based PWM scheme.