Hybrid electronic control system and method for cold weather garment

Abstract

A hybrid, open-loop electronic temperature control system and method of heating for an electrically heated cold weather garment having a plurality of independent heating zones. In one embodiment the system includes: a plurality of conductive heating wires, with at least one such heating wire being disposed in each zone of the garment and operable to heat each zone of the garment independently; a plurality of solid-state semiconductor power switching devices for controllably allowing current flow through each heating wire; and plurality of power selection circuits, with each having a potentiometer and being associated with each solid-state power switching device, for providing individual power level selection for each heating wire of the garment. This gives the wearer individual control over the temperature level of each zone of the garment. Further power control is provided by a master power level selection circuit and potentiometer which operates to simultaneously and uniformly increase or decrease the overall power level applied to the switching devices, which increases or decreases uniformly and simultaneously the temperature of each of the zones of the garment. A triangular waveform generator is included for providing pulse width modulated control over the heating elements to help conserve electrical power. Overcurrent protection circuitry is also included which monitors the total current drawn by the heating elements.