Control device for electric car

Claim 1

A control device for an electric car driving shunt motor having an armature (A 1 ) and a field coil (SF 1 ) driven by a power source (L), comprising: a first chopper device (CH 1 ) for passing current flow from said power source to said armature; a second chopper device (FCH 1 ) for passing current flow in a forward direction from said power source to said field coil; a third chopper device (FCH 2 ) for passing current flow in a reverse direction from said power source to said field coil; a diode (DF 1 ) connected between said power source and a point between said armature and said first chopper device; means for comparing the voltage across said armature to the voltage of said power source; and means for controlling said first, second and third chopper devices, wherein during a deceleration operation: when said armature voltage is higher than said power source voltage, said controlling means causes said second chopper device to pass increased current, whereby electric power is fed back to said power source from said armature; and when said armature voltage is less than said power source voltage, said controlling means causes said second chopper device to pass substantially zero current, causes said third chopper device to pass current, whereby the voltage produced by said armature is reversed, and caused said first chopper device to pass a controlled amount of current whereby electric power is passed from said armature through said diode to said power source.