Excess voltage protection apparatus for an electric vehicle

Claim 1

In an electrical drive means for a vehicle, said drive means comprising an electrically energizable motor, a control transistor with a plurality of terminals, a contactor, and an input connector having two electrodes for connection to an electrical power source, said input connector also accepting either of two separate connecting units, one of said units being connected to a first power source of a first voltage and the other of said units being connected to a second power source of a higher, second voltage, said motor, said control transistor and said contactor being connected in series between one of said electrodes and the other of said electrodes, a protection circuit for detecting a short circuit state of said transistor and a voltage applied to said electrodes in excess of said first voltage, said protection circuit comprising: a first comparator with a first reference voltage source, means coupling said first comparator to said electrodes for enabling said first comparator to provide an output when the voltage between said electrodes exceeds said first voltage; a second comparator with a second reference voltage source, means coupling said second comparator to said transistor for enabling said second comparator to provide an output when said transistor itself is in a short circuit state; and means for interrupting current to said motor connected to said first comparator and said second comparator and operable by said first comparator when the voltage applied to said electrodes exceeds said first voltage and operable by said second compactor when said control transistor is short-circuited.