A current regulation process and device for a three-phase, static-converter-fed, permanently excited synchronous machine with a trapezoidal magnet wheel voltage. A phase angle sensor is mounted on the motor shaft of the machine and is coupled to an evaluating device providing an actual...http://www.google.ca/patents/US5714857?utm_source=gb-gplus-sharePatent US5714857 - Current regulation process for a three-phase, static-converter-fed, permanently excited synchronous machine 
