초록 ▼

A variable duty cycle power converter operable in a current controlled loop and having means for delivering increased load current at low duty cycles for efficient use of the switching elements in the converter. A current limit is established for maximum duty cycle which allows current flow through

A variable duty cycle power converter operable in a current controlled loop and having means for delivering increased load current at low duty cycles for efficient use of the switching elements in the converter. A current limit is established for maximum duty cycle which allows current flow through the power switching elements near but within the ratings of the devices. The maximum limit is programmed as a function of duty cycle to allow increased load current flow while maintaining the current through the power switching devices within ratings. As a result substantially increased current can be provided at low duty cycles without the need for using power switching devices of increased rating.

대표청구항 ▼

In combination with a battery power source, a propulsion motor, a power converter having controlled switches for controlling power delivered from the battery to the motor and alternate conducting means for maintaining current flow in the motor, the improvement comprising, control means for producing

In combination with a battery power source, a propulsion motor, a power converter having controlled switches for controlling power delivered from the battery to the motor and alternate conducting means for maintaining current flow in the motor, the improvement comprising, control means for producing a demand signal relating to demanded motor current, sensing means for producing a signal relating to actual motor current, duty cycle control means for controlling the duty cycle of the converter to cause the actual current to match the demanded current, means for producing a duty cycle signal having a value dependent on the operating duty cycle of the converter, and means responsive to said last mentioned means for increasing the demand signal at minimum duty cycle and progressively decreasing said demand signal with increasing duty cycle so as to increase torque at low speed while maintaining the current through the controlled switches within ratings.