Patent ID: 7436142

Claim:
Method for maintaining a direct voltage at the input of a DC/AC voltage converter in order to maintain an asynchronous motor in a magnetised state, the input of the DC/AC converter being electrically connected to a DC supply bus of an electric vehicle, this supply bus being able to be connected to and disconnected from a catenary in order to supply the motor, this method comprising, in a free wheel mode during which the vehicle coasts and the bus is disconnected from the catenary: a) a step for magnetising the motor from the direct voltage present on the bus, then b) a step for operating the motor as a generator of alternating voltage and operating the converter as a rectifier for the alternating voltage in order to recharge the bus with direct voltage, wherein, in free wheel mode, the method also comprises: c) a step for stopping the converter when the direct voltage of the bus reaches an upper threshold, then d) a step for maintaining the converter in the idle state as long as the direct voltage of the bus remains higher than a minimum direct magnetisation voltage of the asynchronous motor before returning to step a).