Patent ID: 7659492
Filing Date: 2010-02-09
Classification: B60L,H02H,H05B,Y10S

Abstract:
1. A heating device for heating air in a road, rail, air or water vehicle, the heating device comprising: a plurality of electric heating elements; and a circuit for controlling an initial heating phase of the plurality of electric heating elements by a pulse width modulated (PWM) actuation of each of the plurality of heating elements, wherein the circuit is adapted to generate a successively increasing PWM control voltage for increasing a clock ratio of the pulse width modulated actuation, wherein the circuit is adapted to increase the PWM control voltage in a course comprising a first stage followed by a second stage, wherein the increase of the PWM control voltage in the first stage is more rapid than the increase of the PWM control voltage in the second stage, and wherein the circuit is adapted to phase-shift the pulse width modulated actuations of the plurality of electric heating elements.