US 6,801,009 B2 · Current limitation process of brush and brushless DC motors during severe voltage changes

Abstract

A closed-loop control system for a DC motor includes a DC motor 12, a current sensor 14 for determining a current of the motor, a voltage sensor 32 for measuring a voltage of the motor 12, and a micro-controller 33. The micro-controller is constructed and arranged to (1) compare the determined current with a set point and output a pulse width modulated (PWM) duty cycle to control the motor, and (2) calculate a PWM duty cycle limit based on the measured voltage and compare the outputted PWM duty cycle to the PWM duty cycle limit such that when the outputted PWM duty cycle greater than the PWM duty cycle limit, the outputted PWM duty cycle is set to the PWM duty cycle limit. A method, in a DC motor, of preventing a current surge during severe voltage changes is also disclosed.

Claims16

Dependent claims

A method, in a DC motor, of preventing a current surge during severe voltage changes, the method including:

measuring a voltage of the motor,
comparing the measured voltage to a set under-voltage limit and if the measured voltage is below the under voltage limit, stopping the motor for a certain amount of time and then re-starting the motor,
calculating a pulse width modulated (PWM) duty cycle limit based on the measured voltage, and
comparing an output PWM duty cycle, for controlling the motor, to the PWM duty cycle limit and if the output PWM duty cycle is greater than the PWM duty cycle limit, setting the output PWM duty cycle to be the same as the PWM duty cycle limit.

1 more element

Dependencies are inferred from the claim text.

Current limitation process of brush and brushless DC motors during severe voltage changes

Life of this patent

Current limitation process of brush and brushless DC motors during severe voltage changes

Life of this patent

Abstract

Claims16