Matrix conversion moves closer to the market

Practical matrix-converter-based drives have moved a step closer to commercial reality with the launch of pair of purpose-designed bidirectional IGBT modules by Dynex Semiconductor. Matrix converter power stages, which do away with the need for DC link rectifiers and bulky, unreliable decoupling capacitors, are seen by many experts as being the basis for a future generation of compact, reliable drives.

Essentially, a matrix converter is a controllable array of semiconductor switches that converts a fixed frequency multi-phase input into a variable-frequency, multi-phase output. The use of high-frequency PWM (pulse width modulation) allows the converter to produce an accurate sinusoidal output.

The new Dynex modules are designed specifically for use in matrix converter power stages. One (a 200A, 1.2kV device) is intended for use in high-efficiency brushless DC drives; the other (400A, 1.7kV) for use 60-400Hz fixed frequency converters. According to Dynex, the only downside of the devices is that conduction losses are increased slightly because of the series connection of the IGBTs and series diodes in each bidirectional switch.

Dynex is working with researchers from Nottingham University in the UK to develop a PWM strategy and to determine the best size of switching elements to achieve peak performance from matrix converters.