Electric vehicle supply equipment with temperature controlled current
In electric vehicle supply equipment (EVSE), interruption of charging due to overheating is prevented by adjusting the pulse duty cycle on the control pilot conductor communicating the maximum allowed current level to the electric vehicle, the adjustment being performed whenever the EVSE temperature exceeds a predetermined threshold temperature below the maximum operating temperature as a function of the approach of the temperature to the maximum operating temperature.
1. A method for an electric vehicle supply equipment (EVSE) system for charging an electric vehicle, the method comprising:
a) sensing an present temperature; and
b) controlling a pulse generator coupled to a control pilot conductor by reducing a pulse duty cycle of the pulse generator from a nominal pulse duty cycle by a reduction factor that is a function of an increase of the sensed present temperature above a predetermined threshold temperature.
2. The method of claim 1 , wherein the function is a proportional function.
3. The method of claim 1 , wherein the reduction factor is a function of the closeness of the sensed present temperature to a maximum operating temperature.
4. The method of claim 1 , wherein the predetermined threshold temperature is in a range of 10% to 30% of a maximum operating temperature.
5. The method of claim 1 , wherein the electric vehicle responds to a change in pulse duty cycle by changing current draw accordingly.
6. A method for an electric vehicle supply equipment (EVSE) system for charging an electric vehicle, the method comprising:
a) sensing an present temperature; and
b) controlling a pulse generator coupled to a control pilot conductor by reducing a pulse duty cycle of the pulse generator by a reduction factor that is a function of a closeness of the sensed present temperature to a maximum operating temperature, whenever the sensed present temperature exceeds a predetermined threshold temperature.
7. The method of claim 6 , wherein the function is a proportional function.
8. The method of claim 6 , wherein the predetermined threshold temperature is in a range of 10% to 30% of said maximum operating temperature.
9. The method of claim 6 , wherein the electric vehicle responds to a change in pulse duty cycle by changing current draw accordingly.