Sensorless Vector Control of Permanent Magnet Synchronous Machine Using High-Frequency Signal Injection

The vector control theory of alternating current machines could provide high performance control during transient events, since these methods do not depend on the static equations of the selected machine, but on the space vector-based differential system of equations. These control methods have a very important common property; all of them require an angle, with which the system's input can be transformed into the common reference frame in which the space vector notation is construed. The sensorless control methods attempt to estimate the common coordinate system's angle, without using any information from the encoder, one of which is the high-frequency voltage injection method. This paper presents the mathematical model of the high-frequency synchronous voltage injection method on permanent magnet synchronous machines. The common coordinate system is estimated using a Phase-Locked-Loop (PLL). Based on the detailed mathematical model a new equivalent dynamic model for the PLL structure is proposed, with which the PLL's controller could be tuned, with the knowledge of the machine's parameters and injected voltage properties. Simulation results are provided for an off-the-shelf interior magnet synchronous machine.