Yousheng Wang

Novel sampling algorithm for DSP controlled 2 kW PFC converter

This paper proposes a novel sampling algorithm for digital signal processing (DSP) controlled 2 kW power factor correction (PFCs) converters, which can improve switching noise immunity greatly in average-current-control power supplies. Based on the newly developed DSP chip TMS320F240. a 2 kW PFC stage is implemented. The novel sampling algorithm shows great advantages when the converter operates at a frequency above 30 kHz.

A Bidirectional LLC Resonant Converter With Automatic Forward and Backward Mode Transition

This paper proposes an improved bidirectional LLC resonant topology with a new control scheme. All the switches in the proposed topology can achieve soft switching. Compared with traditional isolated bidirectional dc-dc converters such as dual active bridge converter, the reverse energy and turn-off loss are reduced dramatically, and the conversion efficiency can be much improved. With the proposed new control scheme, the power flow direction and output power of the proposed converter can be changed automatically and continuously, which is attractive for energy storage systems to balance the energy and to keep the dc-bus voltage constant. Performance of the proposed circuit is validated by the experimental results from a 1-kW prototype. Over 97% efficiency is achieved at full load condition based on the prototype.

A new family of soft-switching phase-shift bidirectional DC-DC converters

A new family of soft-switching phase-shift bidirectional DC-DC power converters is proposed. The converters are composed of fundamental switch cells with phase-shift control. They can achieve zero-voltage-switching (ZVS) in both forward and backward modes without increasing voltage or current stresses. The operation principle and analysis of one particular converter, taken as an example of the converter family, are explained. Experimental results are presented.

Minimum-voltage active-clamping DC-DC converters

A family of minimum-voltage active-clamping (MVAC) DC-DC converters is proposed. Differing from the conventional active-clamping converters, MVAC DC-DC converters possess minimum voltage stresses. There is no parasitic voltage ringing across the diode of the converters. Both main switch and auxiliary switch in the MVAC converters can achieve zero-voltage-switching (ZVS) under wide operation range. Operation principle and analysis of a MVAC boost converter are explained as an example of the MVAC DC-DC converters. A MVAC boost converter rated at 1 kW is built to verify the operation and the analysis.

A Bidirectional Three-Level LLC Resonant Converter With PWAM Control

This paper proposes a bidirectional three-level LLC resonant converter with a new pulse width and amplitude modulation control method. With different control signals, it has three different operation modes with different voltage gains. Therefore, it can achieve wide voltage gain range by switching among these three modes, which is attractive for energy storage system applications needing wide voltage variation. The proposed topology operates with constant switching frequency, which is easy to implement with digital control, and it can achieve soft switching for all the switches and diodes in the circuit as a conventional LLC resonant converter. The performance of the proposed converter is validated by the experimental results from a 1-kW prototype with 20 A maximum output current.

A novel DSP controlled 2 kW PFC converter with a simple sampling algorithm

This paper proposed a DSP controlled 2 kW PFC converter with a novel sampling algorithm which can greatly improve switching noise immunity in almost all average current control power supplies. Based on the newly developed DSP chip TMS320F240, a 2 kW PFC stage designed as the front-end of a frequency-variable air-conditioner is implemented. The novel sampling algorithm shows great advantages when the switch operates in the range above 30 kHz.

The voltage sharing of commercial IGBTS in series with passive components

In order to handle high voltage with limited voltage rating self turn-off devices, it is necessary to give a simple and reliable series connection technique of these devices, especially IGBTs for high voltage applications. This paper proposes a snubber circuit to guarantee the voltage balance for IGBTs in series connection both at static and dynamic transients. The proposed circuit features with simple control at the gate side, unlimited number of devices in series, high reliability and low loss. The simulation and experimental results verify these advantages. A 10A/3000V prototype with three series-connected IGBTs have been designed and implemented. It has exhibited excellent dynamic voltage balance and an accepted overshoot level with LC snubber circuits and auxiliary clamp circuits.

A family of compound active-clamping DC-DC converters

A family of compound active-clamping (CAC) DC-DC power converters is proposed. Both main switches and auxiliary switches in the converters can achieve zero-voltage-switching (ZVS), and their voltage stresses are low. There is no parasitic voltage ringing across the diodes of the converters. Operation principle and analysis of the CAC boost converter are explained. A CAC boost converter rated at 1 kW is built to verify the operation and the analysis.

Bidirectional LLC resonant converter for energy storage applications

This paper proposes a new LLC resonant DC-DC topology with bidirectional power flow capability. All the switches in the proposed topology can achieve zero voltage switching (ZVS) at turn on, and zero current switching (ZCS) is achieved for the output side switches at turn off. Compared with the traditional bidirectional dual active bridge (DAB) converter, the turn off current is greatly reduced, and the frequency modulation control scheme can almost eliminate the large circulating energy. Therefore, the conversion efficiency can be much improved, which makes it quite attractive in energy storage applications. The output characteristic of the proposed LLC converter is different from the conventional unidirectional LLC resonant converter. A new analytical model is also proposed in this paper. The detailed operating principle and performance of the proposed topology are analyzed. And a 1 kW prototype is built to verify the theoretical analysis. Over 98% efficiency is achieved base on the prototype.

Dead-time Compensation Based on the Improved Space Vector Modulation Strategy for Matrix Converter

In the control of matrix converter, multi-step current commutation from one input phase to another needs dead-time for safe commutation, so like the dead-time effect in VSI, there is unwanted output voltage error occurred. In this paper, first, the widely used multi-step current commutations procedure and the corresponding output voltage error under the space vector modulation (SVM) is analyzed, then, the scheme of dead-time compensation based on the improved SVM is proposed, the scheme compensates the output voltage error by correcting the space vectors duty time. The experimental results show that the scheme is not only available but also it add no hardware to the system, and it is easy to be fulfilled by the control system