Observer based sensorless predictive hysteresis control of a transverse flux machine

The transversal flux machine DYNAX attracts with a high torque and high power density design while maintaining a favorable production process. The machine´s rotor angle is estimated without sensor in order to address cost sensitive higher volume applications. The sensorless control algorithm evaluates measured and observed phase currents. This observed currents and other machine parameters enable simplicity and performance of the predictive hysteresis control, which would be unstable by exclusive use of measured currents because of the sensor´s dead time and limited bandwidth. This work summarizes basic principles of predictive hysteresis control and discusses it´s embedding into the observer structure designed for sensorless angle estimation. In addition to that, a solution for a nearly constant average switching frequency is addressed and a field weakening algorithm for hysteresis control including overmodulation in motoring operation is presented. Closing with convincing results, the benefits of the combination of sensorless angle control and hysteresis current control are presented.