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In this paper, a program-controlled current source system which is based on direct digital frequency synthesis technology has been proposed. The system adopts PIC16F877 microcontroller as the control center, chooses the AD9850 chip to achieve the program. Through closed-loop design, software use discrete incremental digital PID algorithm to realize precise control of output current system of small...
To analyze the steady state equivalent circuit model of an induction motor to establish the equation that justify the use of a constant V/f speed control of open loop and closed loop control. The main objective is to maintain the speed at fixed reference. To investigate the control schemes for controlling induction machine, particularly the scalar control and vector control method and to evaluate...
The starting current is big and the torque is small when the motor begins to start with the nominal voltage .The discrete variable frequency method can solve the above two questions, at the same time brings the torque oscillation.The paper analyses the cause in detail, and then presents the solved method: the combination between discrete variable frequency method improvement and power factor closed...
A novel hybrid control based on digital variable-band hysteresis discrete pulse modulation (DPM) control and repetitive control is proposed for a 400 Hz inverter. The good dynamic response of the DPM inverter is obtained by the digital hysteresis control, and the steady state control performance is improved significantly by the repetitive control. By utilizing the variable hysteresis band, the stability...
A search is undertaken to obtain optimal settings for hydraulic turbine governors in isolated operation. The scope of this optimization process is to maximize the stability margins of the closed frequency control loop. The settings obtained are very close to those suggested by the classical Paynter formulas. Then a regulating capacity chart is derived that gives, for different values of the water...
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