Design and analysis of high-frequency matrix converters for induction heating

Radio frequency (R.F.) induction heating requires a high frequency AC power supply, typically 100-200 kHz. However, the conventional AC-DC-AC converter topology makes use of large energy storage components, and requires complicated control algorithms to provide a unity power factor sinusoidal input current. A DC power supply is usually assumed to be available in other cases, requiring power quality improvements for interfacing to the utility supply. Recently, matrix converters offering direct AC-AC conversion whilst requiring near-zero energy storage components, have attracted a great deal of attention. Although matrix converters are well-known for synthesising relatively low frequency outputs from the utility supply, there remains limited material concerning the use of matrix converters for high frequency applications, viz. induction heating. Generally, as fast switching devices are utilised in matrix converters, it is possible to make a high-frequency matrix converter.

The primary goal of this project has been to explore the possibility of making high-frequency, high performance matrix converters for induction heating, allowing more compact and reliable power converters to be realised, by removing bulky energy storage components of the DC-link found in traditional approaches.

Novel high-frequency single-phase and 3×2 matrix converters, featuring unity input power factor, very low input total harmonic distortion, soft-switching over the full power range, and high efficiency, have been developed, implemented and experimentally verified, requiring very low computational power in control systems. Further investigation in efficiency improvement, utilising synchronous rectification algorithms, has also been carried out, with experimental verification.

High-frequency 3×2 matrix converter for induction heating