抄録
Almost all methods for sensorless drive of permanent-magnet synchronous motors (PMSMs), which estimate rotor phase using fundamental components of stator voltage and current, cannot operate properly at low speed including standstill. For proper sensorless drive of PMSMs, they must be started and driven up to a certain speed by other methods. This paper proposes a new simple vector control method for a starter, which can start and drive PMSMs from rest up to the 50% rated speed. The proposed vector control method has the following useful features: 1) It is constructed on basis of “MIR strategy" together with feedback current control, and has a new specific stability function preventing rotating oscillation; 2) It can start up PMSMs with less than 50-70% rated load; 3) It can prevent over-current even at very low speed including standstill; 4) It can be applied to both of salient and nonsalient pole PMSMs; 5) It does not require motor parameters of high precision; 6) It is simple and required computational load is very light; 7) It starts up PMSMs with pre-specified maximum current and automatically reduces current amplitude to the necessary minimum; 8) It attains pre-specified ratio of effective/reactive currents at steady state; 9) It can estimate properly rotor phase as well as speed at speed of 10% rating or more. This paper presents the new vector control method in detail from principle and confirms its usefulness by experiments.
