Pulsed power supply

An apparatus for controlling current flow in a load, comprising:

• a power source for supplying unipolar voltage;
• switching means for selectively connecting said power source across said load for applying the voltage with a first polarity during a first time interval and for applying the voltage with a second polarity opposite said first polarity during a second time interval, said switching means including a first pair of normally open switches connected to the opposite ends of said load and responsive to a switch control signal of a first polarity for connecting said power source to said load for applying the voltage with said first polarity during said first time interval and said switching means including means responsive to said switch control signal for generating a first pulse train of alternating polarities during said first time interval and transformer means connected between said means for generating said first pulse train and said first pair of normally open switches;
• and
• control means for generating said switch control signal having a first polarity of a duration defining said first time interval and a second polarity opposite said first polarity of a duration defining said second time interval.

An apparatus for controlling current flow in a load, comprising:

• a power source for supplying unipolar voltage;
• a full-wave rectifying diode bridge connected between said power source and said load for blocking current flow in said load;
• a first pair of transistors each connected in parallel with a diode of said rectifying bridge and connected to opposite ends of said load for selectively connecting said power source across said load for applying the voltage with a first polarity during a first time interval;
• a second pair of transistors each connected in parallel with a diode of said rectifying bridge and connected to opposite ends of said load for selectively connecting said power source across said load for applying the voltage with a second polarity during a second time interval;
• control means for generating a switch control signal having a first polarity of a duration defining said first time interval and a second polarity opposite said first polarity of a duration defining said second time interval;
• means responsive to said switch control signal for generating a first pulse train of alternating polarities during said first time interval and for generating a second pulse train of alternating polarities during said second time interval;
• clock means for defining the period of the pulses of said first and second pulse trains wherein said period is relatively short as compared with the durations of said first and second time intervals;
• transformer means connected between said means for generating said first and second pulse trains and said first and second pairs of transistors;
• and
• time delay means for defining a third time interval during which all of said transistors are turned off during the transition between said first and second time intervals and the transition between said second and first time intervals.

A control for the field winding of a direct current electric motor, comprising:

• a source of a field current command signal;
• means for generating a signal representing the current flowing in said field winding;
• control means responsive to said field current command signal and said field current signal for defining first and secont time intervals wherein said control means includes means responsive to said field current command signal and said signal representing field current for generating a field current error signal, first integrating means responsive to said field current error signal for generating an average field voltage error signal and means for generating a switch control signal having said first and second time intervals for controlling a switching means wherein said switch control signal is generated in response to said average field voltage error signal and said switch control signal;
• a direct current power source;
• and
• switching means responsive to said switch control signal for selectively connecting said power source across said field winding for applying the voltage with a first polarity during said first time interval and for applying the voltage with a second polarity opposite said first polarity during said second time interval.

A control for the armature of a direct current electric motor, comprising:

• a source of a motor voltage command signal including a source of a speed command signal for said electric motor, a source of a signal representing the IR drop in said motor armature, summing means responsive to said speed command signal and said IR drop signal for generating a compensated speed command signal and means responsive to said compensated speed command signal for generating said motor voltage command signal;
• means for generating a signal representing the voltage applied to the motor armature;
• control means responsive to said motor voltage command signal and said applied voltage signal for defining first and second time intervals;
• a power source for supplying unipolar voltage;
• and
• switching means for selectively connecting said power source across said motor armature for applying the voltage with a first polarity during said first time interval and for applying the voltage with a second polarity opposite said first polarity during said second time interval.