Abb Schweiz Ag

Herantis Pharma Plc.

Veli-Matti Leppanen

Mart Saarma

Sjoerd Bosga

Yujing Liu

Mehanathan Pathmanathan

Raimo Tuominen

Päivi Lindholm

Maria Lindahl

Robert Chin

Jaan-Olle Andressoo

Merja Voutilainen

Mikko Airavaara

Johan Peranen

A commutation circuit includes a coil connected to an H bridge, the H bridge including four main switches for reversing polarity and a resulting coil current in the coil. The commutation circuit further includes a voltage source configured to generate a bypass current, and at least one auxiliary switch for controlling the bypass current to thereby decrease a switch current through at least one of the main switches. By generating an appropriate bypass current with help of a voltage source, a switch current through a desired main switch in a leading state can be decreased and eventually brought to zero. Zero current in its turn enables the use of thyristors as main switches as it results in the thyristors to be turned off automatically. Furthermore, decreased switch current at the switching moment reduces switching losses even in different types of switches such as GTOs and IGBTs.

High efficiency commutation circuit

Growing community of inventors

Helsinki, Finland

Veli-Matti Leppanen