A New Current-Ratio-Oriented Simple Vector Control Method for Starting Up Sensorless Drive of Permanent-Magnet Synchronous Motors - Feedback Control of Effective Reactive Currents Based on "MIR Strategy"

Almost all methods for sensorless drive of permanent-magnet synchronous motors (PMSMs), which estimate the rotor phase using fundamental components of the stator voltage and current, cannot operate properly at low speeds including standstill. For proper sensorless drives 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 starting and driving PMSMs with 50-70% rated load from a rest up to 20% rated speed by the rated current. Usefulness of the proposed method having several attractive features is confirmed by experiments