Phase-Shift Modulated Full-Bridge Power Inverters

Opportunity

Power electronic devices, such as power MOSFETs and insulated gate bipolar transistors (IGBT), have significantly advanced electrical energy conversion, driven by improvements in switching speeds and power capabilities. Recent progress in wide‐bandgap (WBG) semiconductor technology further expands the switching frequency range and power ratings of these devices. Power converters utilising this technology can operate at hundreds of kilo‐Hertz in commercial switched mode power supplies (SMPS) and are being considered for applications with switching frequencies up to tens of Mega‐Hertz, such as wireless power transfer (WPT). 

Power inverters are essential for numerous modern applications, including switched mode power supplies, battery chargers and wireless charging systems, with markets worth tens of billions of US dollars. This invention is applicable to a wide variety of uses, including wireless charging for mobile phones and mobile robotics, such as robotic lawn mowers and vacuum cleaners.

Technology

This invention involves a new and low‐cost augmented circuit that can be added to a phase‐shift modulated power inverter, enabling all power switches to be soft‐switched across all operating regions. This innovation reduces switching power loss and allows for higher operating frequencies. A major limitation on switching frequency is the switching power loss in power converter switches. This invention addresses this by incorporating a passive circuit that facilitates soft‐switching, reducing switching power losses and electromagnetic interference (EMI) radiation. The passive circuit comprises two diodes, two capacitors and one inductor, without any fully controlled power electronic switches. This configuration creates near‐zero voltage conditions for the switching processes of power switches in phase‐shift controlled power inverters. 

Applications & Advantages  

Main application areas include switched mode power supplies, battery chargers and wireless charging systems. 

Advantages: 

• The circuit has fewer components than existing methods, making it cost-effective.
• Eliminates the need for an extra gate drive circuit for power switches.
• Can be added to existing phase‐shift modulated power inverters.
• Enables soft switching (through zero‐voltage switching) across the entire operating range, improving efficiency and performance.