A High Efficiency Linear Power Supply with Pure Sine Wave for High Voltage Test

Abstract

The input part of the high-voltage test power supply is usually composed of switching devices; however, the pulse-type periodic interference caused by the switching devices makes the monitoring of the test power supply partial discharge more difficult. Therefore, this paper proposes a high-efficiency and distortion-free linear power supply based on piecewise-linearization with all N-type transistor. Under the same DC input, multiple power transistors are connected to different taps of the same transformer. By controlling the period of linear conduction of each power transistor in turn, we ensure that the power transistor works on the linear side (biased towards saturation) to reduce its conduction voltage drop and the output realizes sinusoidal piecewise linearization, so that the converter can greatly improve the system efficiency. After that, from the perspective of the lowest sum of the transistor loss, an optimization method for the design of the multi-winding transformer ratio at each stage is proposed. Finally, a power supply prototype based on four-piece linear converter with an output voltage of 220 V was built. The experimental efficiency reaches 87.03%, and, additionally, if the linear amplification is divided into more sections, the efficiency can be further improved.