Showing papers by "Huai Wang published in 2010"

Predictive control of buck converter using nonlinear output capacitor current programming

Abstract: A predictive control of buck converter to achieve fast transient response is presented. The methodology is based on using the output capacitor current and instantaneous output voltage to predict the output voltage at the end and mid of a switching cycle to determine the state of the main switch. Two switching criteria, one for switching on and one for switching off the main switch, will be formulated. The operating principles of the control method and all possible cases in the operation will be discussed. The proposed control method has been verified with experimental results of a 50W, 12V/5V buck converter prototype. The controller is realized by analogue devices. The steady-state and transient response to large-signal disturbances will be discussed.

A new concept of high input voltage to low load voltage (1500 V – 48V) DC-DC conversion with hybrid ZVS-ZCS and asymmetrical voltage distribution

Abstract: A new dc-dc converter with asymmetrical voltage distribution between two primary switch pairs is proposed. It allows an implementation with popularly used MOSFETs for the low-voltage switch pair and IGBTs for the high-voltage switch pair, giving the optimal option for a particular class of high-voltage applications. A new hybrid zero-voltage-switching (ZVS)-zero-current-switching (ZCS) technique, which is different from the ZVZCS solution, is proposed. A secondary-side snubber is used to achieve ZCS of all IGBTs in the IGBT pair; its resonant energy is fully released to the load. The energy used for achieving ZVS for the upper MOSFET in the low-voltage switch pair at the transition from the freewheeling to energy transfer stage is provided by the primary-side input capacitor and dc-blocking capacitor. All IGBTs and MOSFETs in the proposed structure are soft-switched from very light load to full load. The duty cycle of the upper switch in each pair determines the voltage distribution between the switch pairs. It is controlled by a simple PWM. A 2kW, 1500/48V experimental prototype has been built and evaluated. The experimental results confirmed the theoretical predictions.

Analysis and optimized design of an efficient high-voltage converter with high output capacity

Abstract: This paper presents the analysis and design of a new class of multiphase converter for high-to-low voltage applications. The converter features a V i /n voltage stress on the primary-side switches, which are commutated under zero voltage switching (ZVS), and I o /n current stress on the output inductors and rectifier diodes. A DC analysis allows for deriving the duty-cycle loss and the ZVS load range. A tradeoff design is performed for optimizing these two conditions. The proposed converter is favorably compared with available solutions from the point of view of number of switches and the voltage stress to which they are submitted. Experimental results based on a 1500V/48V, 2 kW prototype verify the theoretical predictions.