APPARATUS AND METHOD FOR ADDITIONAL ELECTRICAL HEATING DEVICE OF VEHICLES

摘要

A secondary electric heating device of vehicle and a method thereof are provided to protect a battery and decrease the load of the battery by controlling a duty ratio of a PWM signal. A secondary electric heating device of vehicle comprises: a switching unit(206) switching the battery voltage according to a PWM signal; and a heater unit(214) including a heating member connected to the switching unit. The current sensor(222) detects a current flowing through the heater unit. A controller(224) increases and decreases a PWM duty of the PWM signal. The controller sets up a target power comparing the battery voltage with the reference voltage. The PWM duty of the PWM signal increases and decreases according to a comparison result of the target power and power consumption.