초록 ▼

Stabilized operation of a damperless synchronous motor, which is driven by a voltage source inverter energized by a d-c bus voltage, is obtained under transient conditions, such as during sudden variations of load torque, in order to maintain the torque angle in the motor relatively stable at all ti

Stabilized operation of a damperless synchronous motor, which is driven by a voltage source inverter energized by a d-c bus voltage, is obtained under transient conditions, such as during sudden variations of load torque, in order to maintain the torque angle in the motor relatively stable at all times and within the stability limit. This is achieved by employing transient changes in either the d-c bus voltage, the d-c bus current or the motor voltage, which changes reflect transient variations of the torque angle, to rapidly adjust the inverter frequency as necessary to hold the torque angle reasonably constant. For example, if there is an abrupt load increase on the motor, the bus voltage tends to drop and the motor tends to slow down, the torque angle thereby tending to increase. The extent to which the angle tends to increase will, however, be rapidly reduced by dynamically decreasing the inverter frequency so that the rotating magnetic flux or mmf, produced by the stator windings of the motor, slows down to preserve the desired torque angle. When there is a normal variation in load demand, necessitating a different steady state motor speed, a set point voltage may be varied to change the amplitude and frequency of the inverter output voltage to the steady state levels needed to drive the motor at the new required speed.

대표청구항 ▼

A control system for controlling and stabilizing the operation of a damperless synchronous motor driven by the output a-c voltage developed by a voltage source inverter from an adjustable d-c bus voltage received over a d-c bus from a controlled d-c power supply having a low internal impedance, both

A control system for controlling and stabilizing the operation of a damperless synchronous motor driven by the output a-c voltage developed by a voltage source inverter from an adjustable d-c bus voltage received over a d-c bus from a controlled d-c power supply having a low internal impedance, both the d-c bus voltage and the torque angle in the motor being subject to transient variations under transient conditions, said control system comprising: means for establishing the amplitude and frequency of the inverter output voltage at desired steady state levels; means for developing a control voltage which is a function of the d-c bus voltage or motor voltage and includes information indicating any sudden torque angle change; and stabilizing means, controlled by said control voltage, for rapidly adjusting the inverter frequency anytime the torque angle tends to suddenly vary in order to reduce the extent to which the angle tends to change, thereby maintaining the torque angle relatively stable under transient conditions and within the stability limit of the motor.