Sensorless magnetic model and pm flux identification of synchronous drives at standstill

Abstract

Abstract-This paper proposes a sensorless self-commissioning technique for PM-assisted synchronous reluctance motors. The identification of the machine's flux maps is performed at standstill without any position transducer and with no need of rotor locking. The machine is first excited with alternated high voltage pulses, injected in the estimated d and q directions of the rotor to determine its saturation curves. Then, direct current values are applied in a fixed stator direction so that the rotor aligns in specific positions giving information on the PM flux linkage. Experimental results are provided on a PM-assisted synchronous reluctance motor prototype, confirming the validity of the proposed method. The key original feature of the proposed work is the estimation of magnet flux linkage at standstill. For the motor under test, the magnet flux linkage was sensorless estimated at standstill with an error lower than 3%.

Optimal Torque Control of Saturated Synchronous Motors: Plug-and-Play Method

“…This identification method needs only the measurements of the phase currents and the DC-bus voltage, while neither motion sensor nor AC-side voltage sensors are needed. If the motor is equipped with PMs, the constant i f can be calculated based on the nameplate data, measured using the no-load test, or identified at standstill [25]. In practice, the constant i f depends on the temperature, but the dependency is omitted here.…”

“…When combined with an identification method for the magnetic model, the proposed method enables the plug-and-play start-up of an unknown motor. Various identification methods for the magnetic model of SyRMs, PM-SyRMs, and interior PM synchronous motors are already available [23]- [25].…”

The Impact of the Control Strategy in Flux Observer Based Sensorless Control of Synchronous Reluctance Motors

“…Model based flux-observers can be combined with signalinjection techniques to benefit from their respective good performance in the high and low speed ranges, [18]- [20]. To improve the accuracy of the estimation, especially at low-speed operation, FE mapped flux model [21], or self-commissioning techniques [22], [23] can be used. Kojima et al in [24] introduce a correction factor that takes into account the machine saturation and a torque-dependent gain to correct the position error.…”