Electric vehicle drive train with contactor protection

A drive train for an electric vehicle, said drive train comprising:

• a traction battery;
• power drive means connected to said traction battery for driving one or more wheels of the vehicle, said power drive means comprising an electric motor, gating means for permitting control of power delivered to said electric motor, said gating means comprising a substantially capacitive input filter;
• a main contactor having a pair of contacts electrically connected between said traction battery and said capacitive input filter, said contacts being movable between a closed position and an open position for respectively connecting and disconnecting said traction battery and said power drive means;
• and
• control means connected to said main contactor for operating said main contactor to move said contacts to one of the open position and the closed position, said control means comprising voltage detecting means for detecting a voltage across said contacts, and power drive inhibit control means connected to said gating means and responsive to said voltage detecting means for inhibiting said power drive means from delivering power to said electric motor responsive to a voltage across said contacts exceeding a predetermined value to prevent discharge of said capacitive input filter and to thereby reduce a voltage impressed across said contacts when said contacts move from the closed position to the open position.

An electric vehicle comprising:

• a frame;
• one or more wheels rotatably mounted on said frame;
• a traction battery carried by said frame;
• power drive means connected to said traction battery for driving one or more wheels of the vehicle, said power drive means comprising an electric motor, gating means for permitting control of power delivered to said electric motor from said traction battery, said gating means comprising a substantially capacitive input filter;
• a main contactor having a pair of contacts electrically connected between said traction battery and said capacitive input filter of said power drive means, said contacts being movable between a closed position and an open position for respectively connecting and disconnecting said traction battery and said power drive means;
• precharging means connected to said traction battery and said capacitive input filter for charging said capacitive input filter when said contacts are in the open position;
• and
• control means connected to said main contactor for operating said main contactor to move said contacts to one of the open position and the closed position, said control means comprising precharging control means cooperating with said precharging means for charging said capacitive input filter prior to moving said contacts to the closed position from the open position, voltage detecting means for detecting a voltage across said contacts, and means responsive to said voltage detecting means for operating said contactor to prevent said contacts from being moved to the closed position from the open position responsive to a voltage across said contacts exceeding a predetermined value.

A method for operating an electric vehicle drive train including a traction battery;

• power drive means connected to the traction battery for driving one or more wheels of the vehicle, the power drive means including a substantially capacitive input filter;
• and a main contactor having a pair of contacts electrically connected between the traction battery and the capacitive input filter of the power drive means, the contacts being movable between a closed position and an open position for respectively connecting and disconnecting the traction battery and the power drive means;
• said method comprising the steps of:
• detecting a voltage across the contacts of the main contactor;
• precharging the capacitive input filter to a predetermined value prior to controlling the main contactor to move the contacts from the open position to the closed position;
• and
• controlling the main contactor to prevent the contacts from being moved to the closed position from the open position responsive to a voltage across the contacts being above a predetermined value.