On-line switching between two control parameters

A circuit arrangement adapted to provide smooth transition between voltage and speed control of the motor of a motor-generator set, comprising

• a first circuit means for comparing a voltage reference signal and a signal representative of the speed of the motor of the set, and providing an output signal that is indicative of any difference existing between the levels of the voltage reference and speed signals,
• a second circuit means connected to receive the output signal from the first circuit means and a signal representative of the current in the armature of the motor, and for producing a second output signal that is indicative of any difference existing between the first output signal and the current in the motor armature,
• means for directing the output of the second circuit means to a voltage regulator of the generator to maintain excitation of the generator field at a value determined by the voltage and current references,
• means for disconnecting the voltage regulator of the generator from the second circuit means,
• a third circuit means for developing a voltage control signal for the generator field, and means for applying this signal to the generator field when the field is disconnected from the second circuit means, and
• a fourth circuit means for comparing the voltage control signal developed by the third circuit means to the output of the second circuit means, and for causing said output of match that of the voltage signal developed for the voltage regulator.