Speakers
Description
Interior permanent magnet synchronous motors (IPMSM) are widely applied to various industry applications such as electric vehicle, wind power generator, industrial servo motor, and home appliance due to advantage of wide speed range, high power density, high efficiency and excellent control performance. To realize a high performance and reliable IPMSM drive system, the exact knowledge of the IPMSM parameters is indispensable. Since IPMSM has a cross saturation, motor parameters change nonlinearly with electric current magnitude and phase angle. Inaccurate parameters can cause problems with output degradation, low efficiency operation, and even out-of-synchronization. Especially, as the change of inductances varies irregularly depending on the power, shape, and operating characteristics of motor, the incorrect estimation of inductances reduces motor operation performance. Thus, accurate real-time estimation of inductances is a necessary factor in designing the controller and ensuring excellent control performance.
The advantage of the offline parameter estimation techniques is that it is easy to implement with a simple algorithm. Nevertheless, there is a disadvantage that additional equipment is required and measurement errors are caused by measurements performed at a single point.
The online parameter estimation techniques are introduced as the model reference adaptive control techniques, observer-based techniques, extended kalman filter based Techniques, and neural network techniques. These techniques are suitable for applications that have various operation ranges, because it is estimated during operation.
Previous technologies have the disadvantage that it does not take into account the irregular operating conditions of the motor or requires complex calculations. Additionally, the magnetic flux is required for the conventional parameter estimation techniques, which can vary due to the motor temperature or magnetic saturation. Thus, it is difficult to exactly estimate a parameter.
This Letter proposes a new method with online parameters identification using electric torque estimator without considering the magnetic flux. This estimator is made up of dq axis voltage and current parameter so that the torque of the IPMSM can be calculated without additional equipment.
