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Investigation_of_Effectiveness_of_Sensorless_Operation_in_CarrierSignal-Injection-Based_Sensorless-Control_Methods 南台科技大學電機工程系 來源: Zhu, Z. Q. Gong, L. M., “Investigation of Effectiveness of Sensorless Operation in Carrier-Signal-Injection-Based Sensorless-Control Methods,” IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 58, NO. 8, pp. 3431 – 3439, AUGUST 2011. 學生:林柏辰 指導老師:王明賢 Abstract—This paper investigates the effectiveness of sensorless operation in carrier-signal-injection-based sensorless-control methods for permanent-magnet brushless ac motors. The sensorless safety operation area (SSOA) is introduced with due account for the quantization error in the analog to digital conversion. The SSOA defines a working area in the d–q plane in which the motor can operate in sensorless mode with a guaranteed performance in steady state. With the aid of SSOA, a proper injected carrier signal can be selected for the specific prototype machine and current-measurement resolution. Experimental results confirm that the performance of sensorless operation can be guaranteed when the machine operates inside the SSOA with cross-saturation compensation. INTRODUCTION SENSORLESS control of permanent-magnet (PM) brushless ac (BLAC) motors is attractive for its inherent advantages, such as increased reliability, reduced cost and size, etc. Its techniques can be categorized into two major types: fundamental-model-based and saliency-tracking-based methods. The algorithms relying on the fundamental model consist of the back-electromotive-force-based [1]–[9] and fluxlinkagebased methods [10]–[13]. They have the advantages of straightforwardness and simplicity, and a good performance can be achieved in the middle and high-speed regions. However, under the conditions of low speed and standstill, the fundamental model of a machine usually results in the failure of sensorless control. To solve this problem, saliency-tracking-based methods are developed [14]–[26]. Due to the inherent saliency of PM BLAC motors resulting from either geometrical rotor saliency or saturation-induced saliency, the position information can be tracked via position-dependent current response by injecting discrete voltage pulses [14], modified pulsewidth-modulation pulses [15] or continuous high-frequency carrier-voltage signal [16]–[26] into the motors. EXPERIMENTAL RESULTS The hardware platform to evaluate the effectiveness of sensorless operation is constructed based on a TMS320C31 floating-point DSP. Three dedicated 12-b AD converters are used to measure the phase current with the aid of current transducers. To verify the accuracy of the estimated rotor position, the real rotor position from an encoder with a resolution of 1024PPR is provided to the DSP. The calculation rate of the current loop is configured to be 5 kHz, which is the same as the current-sampling frequency. End