A Novel Position Observer for Interior Permanent Magnet Synchronous Machine

The model of the interior permanent magnet synchronous machine (IPMSM) is transformed to a new form, which can be treat as a surface permanent magnet synchronous machine (SPMSM). Based on the new model, novel methods for position estimation during standstill and low speed are presented. Carrier-signal-injection is used; high frequency, persistent, rotating current vector is injected into the plant. The model reference adaptive method is used to demodulate the position signal from high frequent current signals, taking over filter method. The new algorithms can identify and track the north pole of the d or q axes directly and accurately even when the rotor is at standstill and low speed. The influences of the selection of carrier signal, the current regulation and the conditions on the performance are studied. Simulation results show that the proposed algorithms are capable of reliable and fast initial position estimation at standstill and low speed