A New High-Frequency Voltage Injection Method for Sensorless Drive of Permanent-Magnet Synchronous Motors with Pole Saliency

Abstract

This paper proposes a new sensorless vector control method for salient-pole permanent-magnet synchronous motors. In regard to rotor phase estimation, the sensorless vector control method is featured by a new high-frequency voltage injection method distinguished from the conventional ones by a unique ellipse shape of the spatially rotating, and by a new PLL method whose input is a high frequency current auto-correlated signal. The new vector control method established by two innovative technologies can have the high-performance and attractive features as follows.1) It can allow 250% rated torque at standstill.2) It can operate from zero to the rated speed under the rated motoring or regenerating load.3) It accepts instant injection of the rated load even for zero-speed control. 4) It accommodates a load with huge moment of inertia. 5) Phase estimation is very robust against inverter dead time. 6) Computational load for estimating rotor phase is very small, would be the smallest among the methods with comparable performance. This paper presents the new vector control method by focusing on two innovative technologies from its principles to design rules. Usefulness of the new vector control method is verified through extensive experiments. Fig. 1 shows a structure of the proposed new sensorless vector control system. Phase and speed of the rotor are estimated in the "phase estimator," whose structure can be illustrated as in Fig. 2. As shown, it simply consists of two single-input/output band-pass filters, a single-input/output low-pass filter, a phase synchronizer, and a speed-variable-ellipse high-frequency voltage commander (SVE-HFVC). The phase synchronizer is a kind of so-called PLL, but whose input is a high-frequency current correlated signal. SVE-HFVC generates high-frequency voltage command of unique ellipse shape. The phase estimator is very simple, but its performance is excellent as demonstrated in the following. Fig. 3 shows a example of torque responses at standstill to the 250% rating torque command, where wavelike data imply, from the top, q-current, u-phase current, actual rotor phase and its estimate. It is clearly observed that the phase is well estimated and 250% rated q-current (torque-producing current) is well controlled although the rotor starts to rotate at instant of torque command injection due to narrow speed bandwidth of the load machine controlled to be zerospeed. -20 -

A new generalized high‐frequency voltage injection method and mirror‐phase estimation method for sensorless drive of salient‐pole PMSMSs

“…The following theorem asserting the speed independence of the high-frequency current is true for the high-frequency voltage (34) [1,2].…”

“…This approach is rather new. One of the few existing field studies was conducted recently by Shinnaka; in particular, the speed-varying elliptic high-frequency voltage injection method was proposed in combination with a high-frequency current correlated-signal algorithm for phase estimation [1,2].…”

“…This method does not require data on the driving voltage and current, and hence stable phase estimation can be accomplished even at zero speed when the driving voltage S/N decreases considerably [1][2][3][4][5][6][7][8][9][10][11][12][13][14][20][21][22].…”

“…In straight-line high-frequency voltage injection, the rotor phase can be estimated by the FFT algorithm proposed by Aihara and colleagues [7], the 45° impedance method proposed by Ha, Ide and colleagues [8], the scalar heterodyne method proposed by Jang and colleagues [9,14], or the high-frequency current correlated-signal method proposed by Shinnaka and Holtz [1,2,10], etc.…”

Audible Noise Reduction Method in IPMSM Position Sensorless Control Based on High-Frequency Current Injection

“…These methods present good performance at standstill and low-speed range drive of the IPMSM. The saliency based sensorless methods have to inject high-frequency current (3) , high-frequency voltage (4)- (6) , or pulse voltage (7) . But, audible noise is a concern when a highfrequency signal is injected.…”