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AssigneeHitachi, Ltd.
InventorsToshiyuki Ajima, Hideki Miyazaki, Yukio Kawabata, Kiyoshi Sakamoto, Takao Yanai, Osamu Koizumi
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A rotary sensor that outputs two analog signals, such as one sine wave and one cosine wave and has multiple periods within one period of the electrical angle of a motor is employed. The motor is energized at each position for a specified length of time upon its startup by using multiple electrical angles corresponding to the multiple candidate absolute angles obtained from the rotary sensor signal as the initial position of the motor, and the electrical angle at which the motor acceleration becomes maximum is determined as the absolute angle. While the motor drive is in operation, on the other hand, the phase difference Δθ between the phase of the motor at the counter electromotive voltage and the control phase is directly computed from the parameters of the motor, sensed current, voltage command and angle speed so as to correct the shifted position. A high-efficiency motor drive unit with improved maintainability of rotary sensor and improved accuracy of sensing the magnet pole position of a permanent magnet synchronous motor that accelerates and decelerates very quickly in a wide range of speed is realized.
A synchronous motor drive unit comprising a synchronous motor, inverter for supplying variable-voltage & variable-frequency DC to the motor, current sensor for sensing the current through the motor, rotary sensor for sensing the rotating angle of the motor rotor, vector computing means for controlling the motor torque based on the current sensed by the current sensor and rotating angle signal sensed by the rotary sensor, and PWM controller for controlling the inverter by PWM according to the computation result;
A synchronous motor drive unit comprising a synchronous motor, inverter for supplying variable-voltage & variable-frequency DC to the motor, current sensor for sensing the current through the motor, rotary sensor for sensing the rotating angle of the motor rotor, vector computing means for controlling the motor torque based on the current sensed by the current sensor and rotating angle signal sensed by the rotary sensor, and PWM controller for controlling the inverter by PWM according to the computation result;
A method of driving synchronous motor, comprising a synchronous motor, inverter for supplying variable-voltage & variable-frequency DC to the motor, current sensor for sensing the current through the motor, rotary sensor for sensing the rotating angle of the motor rotor, vector computing means for controlling the motor torque based on the current sensed by the current sensor and rotating angle signal sensed by the rotary sensor, and PWM controller for controlling the inverter by PWM according to the computation result;
Dependencies are inferred from the claim text.