Sensorless observer based hysteresis control of a transverse flux machine at full speed range

The power and torque density of transverse flux machines could be advantageous in many applications. However, until now a widespread use of TFMs is restricted by concernings with manufacturing as well as control and sensorics hardware. The first point is resolved by the construction of the TFM DYNAX, which is suitable for series production. Thus the next step is to simplify control hardware. This is achieved by replacement of the machine's exacting angle measurement system by a sensorless control scheme. However, the magnetic circuit with uneven string inductance and operating points without saliency challenges sensorless control at standstill. This work completes previous observer based approaches with a focus on signal injection by a hysteresis controller for operation at standstill and emf tracking at higher speeds. The calibration efford is minimized by adaptive estimation of chosen parameters. The proposed emf tracking algorithm enables advanced features like temperature compensation for constant torque generation and is also valid for PMSM-variants. Measurement results show an excellent sensorless performance in all operating points. The conclusion from this work is that sensorless control of the TFM DYNAX is possible and the system cost can be reduced for many applications without penalty.