회전자 위치센서 없는 동기전동기의 고속 운전 성능 개선

Performance Improvement of High Speed Operation for Sensorless based Synchronous Machine

Abstract

The performance improvement in the high speed region for the sensorless based synchronous machine drive is discussed in the paper. Conventional dynamic overmodulation method in the vector controlled AC driver requires some calculation of maximum amplitude of the applying voltage vector to limit its amplitude, which leads to increase the calculation time of microprocessor. For low performance microprocessor, this might be impossible to complete the control loop within limited control time. Thus, to reduce the calculation time, the constantly limited amplitude for applying voltage vector is tried in this paper to drive sensorless based synchronous motor. Certainly, there exists some errors in amplitude and phase angle between inverter voltage and calculating voltage in the sensorless algorithm. But, this errors are too small to prevent the high speed sensorless operation within overmodulation region. The validities of the proposed method is proved by the experimental results.

Fig. 1 Definitions of stationary(a-b) and synchronously rotating(d-q) reference frames

Fig. 3 Modification of voltage vector according to the proposed overmodulation algorithm

Fig. 4 Normalized magnitude and phase angle errors for the proposed overmodulation algorithm

Fig. 5 Control block diagram of sensorless based PMSM driver

Fig. 6 Phase to ground voltage, estimated rotor position and phase current when the voltage vector is limited on circle 1 [2msec/div]

Fig. 7 Phase to ground voltage, estimated rotor position and phase current when the proposed overmodulation is applied [2msec/div]

Fig. 2 Over-modulation regions and voltage synthesis for SVPWM

Table 1. Parameters of permanent magnet synchronous machine