Sensorless Control of Interior Permanent Magnet Machine at Standstill and Low Speed

The model of the interior permanent magnet synchronous machine (IPMSM) is transformed to a novel format, which can be treated as a surface permanent magnet synchronous machine (SPMSM). Based on the new form, novel methods for position estimation during standstill and low speed are presented for IPMSM drives. Carrier-signal-injection is used; persistent, rotating current vector is injected into the plant. Novel carrier frequency image tracking techniques base on the model reference adaptive method are used, taking over filter method, to demodulate the position signal from high frequent current signals. This scheme can identify and track the orientation of the north pole of d or q axes quickly and accurately even when the rotor is at low speed and standstill, in spite of the speed is known and unknown. Simulation results show that the proposed algorithms are capable of reliable and fast initial position estimation at standstill and low speed