초록 ▼

A field weakening circuit for an electric motor comprises a switching circuit the impedance of which is variable connected in parallel with a field winding of the motor. The switching circuit impedance is variable in dependence upon motor speed and current, either continuously or in a plurality of d

A field weakening circuit for an electric motor comprises a switching circuit the impedance of which is variable connected in parallel with a field winding of the motor. The switching circuit impedance is variable in dependence upon motor speed and current, either continuously or in a plurality of discrete steps, to control the current through the field winding.

대표청구항 ▼

A power supply circuit for an electric motor including an armature in series with a field winding, comprising: a chopper circuit connected in series between the field winding and a power supply for supplying pulses of current from the power supply to said motor, and a field weakening circuit connect

A power supply circuit for an electric motor including an armature in series with a field winding, comprising: a chopper circuit connected in series between the field winding and a power supply for supplying pulses of current from the power supply to said motor, and a field weakening circuit connected in parallel with the series connected field winding and chopper circuit, said field weakening circuit comprising at least one solid state switch in series with a resistor, wherein the impedance of said field weakening circuit may be controlled by varying the conductivity of said at least one solid state switch.