A 5kV/15W Dual-Transformer Hybrid Converter with Extreme 2000X Conversion Ratios for Soft Mobile Robots

Abstract

This paper describes the topology, fundamental operations, and key characteristics of a Dual-Transformer Hybrid converter that is capable of supporting extremely large conversion ratios for future soft mobile robots from an input voltage range of a 1-cell battery pack. The circuit topology employs a unique configuration of a fly-back transformer pair combined with a switched-capacitor network to support ~2000X conversion ratios as well as output voltage regulation with a simple duty-cycle control. The hybrid combination also enables the two compact transformers to complete charge and discharge all flying capacitors for high overall efficiency. The Dual-Transformer Hybrid converter and its operation are verified in a prototype measured up to 5kV output, capable of delivering maximum loads up to 15W from a 1V-3V input, achieving peak efficiency of 75.1% at 1kV/1W and 74.6% at 3.3kV/9W output.