Feldorientierte Regelung der permanenterregten Synchronmaschine ohne Lagegeber für den gesamten Drehzahlbereich bis zum Stillstand

The present work deals with the sensorless field oriented control of surface-mounted permanent magnet synchronous motors. After a short review of the fundamentals of the sensorless control, an overview of the different published methods for the detection of the rotor position is given. Two methods are selected taking into account the requirements for the application in low-cost industrial drives, so that the full speed range can be achieved. The first method is based on the integration of the back EMF induced in the stator coils and is used for position estimation at high speed. At standstill, up to a certain low speed range, a high-frequency test signal method is employed. The combination of the methods into an only structure provides an extra filtering for the injection estimated rotor angle at low speeds without detrimental effects on the dynamic of the estimation. Additionally a smooth transition between both methods is also achieved. The main focus of this work is the practical implementation of the estimation methods by using a commercial inverter, which is commanded within a low-cost 16-bit fixed-point DSP. The problems that arise by the estimation with test signals, such as the need of digital bandpass-filters, dead-time compensation and decoupling of this signal from the current control, are specially discussed in this work. The solutions to these problems for suitable practical implementation are theoretically explained. The experimental results show, that the proposed concept for the sensorless speed control of this type of motors enables the realisation of less expensive and more compact drive solutions for low-end industrial applications.