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AssigneeHitachi, Ltd.
InventorsToshiyuki Ajima, Hideki Miyazaki, Yukio Kawabata, Kiyoshi Sakamoto, Takao Yanai, Osamu Koizumi
Estimating the term…
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 synchronous motor drive unit comprising a synchronous motor, an inverter for supplying variable-voltage and variable-frequency DC to the motor, a current sensor for sensing the current through the motor, a 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 a PWM controller for controlling the inverter by PWM according to the computation result, a rotary sensor that generates a rotary output analog signal with multiple periods within one period of the electrical angle or absolute angle of the motor, means that energizes the motor at each position for a specified length of time upon its startup, by using multiple electrical angles of the motor corresponding to the multiple angles, including an absolute angle of magnetic pole position of the motor, sensed by the rotary sensor as the initial position of the motor, and an initial position determining means that determines the electrical angle at which the motor acceleration becomes maximum among the respective angles of energization as the absolute angle of the motor.
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 a synchronous motor having an inverter for supplying variable-voltage and variable-frequency DC to the motor, a current sensor for sensing the current through the motor, a 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 a PWM controller for controlling the inverter by PWM according to a computation result;
Dependencies are inferred from the claim text.