MSU Technologies

Bidirectional Indirect Matrix Converter Circuit for DC Fast Charging

Executive Summary

Indirect matrix converters (IMCs) are commonly used in AC/AC converters, which comprise a major power electronics component of DC fast chargers, motor drives, and other electrical power converters. A common use is to convert between 120V, 60Hz, 3-phase grid power to 50kHz+ PWM waveforms for use by systems further ‘downstream’. To avoid damage from high frequency harmonics, bulky DC-link capacitors are often used. MSU researchers have developed a bidirectional power electronics circuit with overvoltage protection system for IMC’s used in high powered DC fast charging applications, that eliminates the need for a DC-link capacitor. The innovation is particularly useful for supporting the transition to electric vehicles.

Description of Technology

The technology involves a unique power electronics circuit with bidirectional operation and overvoltage protection. The circuit has been tested extensively in SPICE (simulation software) for 120 VAC systems under a variety of scenarios including both positive and negative current spikes. The circuit is entirely self-triggered by the line voltage rather than controlled and thus requires no costly sensors. A prototype has been built and tested in the lab at 20V operation voltage.

Benefits