Abstract: An electrically powered vehicle includes an inverter mounted in the vehicle, the inverter having a plurality of high power IGBT modules for converting DC power to AC power for application to a plurality of AC electric motors connected in driving relationship to wheels on the vehicle. Each of the IGBT modules is mounted in thermal transfer relationship to an electrically isolated base plate and each base plate has a plurality of closely spaced, parallel slots formed across one surface with a plurality of fins fitted into the slots and extending from the base plate. The system includes apparatus for mounting the IGBT modules to a wall separating an electronics compartment from an air supply and air exhaust compartment. Air from an air supply plenum in the air supply compartment is directed into the fins extending from the IGBT base plate and exhaust through an exhaust conduit. The vehicle includes a blower to force air to flow through the fins extending from the base plate.

Abstract: An electrical power system includes an inverter having a plurality of insulated gate bipolar transistors (IGBTs) and capacitors for converting DC power to AC power and at least one power bus bar including an interconnecting bus bar and a plurality of extension bus bars. The area between the conductors of the interconnecting bus bar and the extension bus bars is minimized to reduce the inductance between the IGBTs and the capacitors. The extension bus bars are each coupled to the interconnecting bus bar and a respective one of the IGBTs and capacitors. An IGBT can be removed from the inverter without removing the interconnecting bus bar or any other IGBT. The capacitors can be positioned at ninety degree angles with respect to the interconnecting bus bar. In one embodiment, the IGBTs are additionally positioned at ninety degree angles with respect to the interconnecting bus bar. In an alternate embodiment, the IGBTs are positioned parallel with respect to the interconnecting bus bar.

Abstract: Apparatus for increasing the available regenerative braking energy and for enabling low current control without frequency variation in a time-ratio controlled main thyristor power circuit for a direct current traction motor. A variable impedance element is serially inserted in a motor armature free-wheeling current path between a free-wheeling diode and the motor armature, the variable impedance element preferably comprising a power resistor and parallel connected thyristor. During electrical regenerative braking the thyristor is used to modulate the power resistor to thereby present a continuously variable impedance in the armature current path. During motoring at very low speeds the thyristor can be operated to modulate the power resistor and thus reduce the minimum controllable level of motor current normally limited to commutation current level without the necessity of reducing the main thyristor operating frequency.

Abstract: A method and control system for minimizing peak current levels in a direct current traction motor drive system in which the traction motor is powered by periodic current pulses metered from a direct current source by a controllable switch. The control system includes apparatus for comparing actual motor current to commanded motor current and for controlling the duty factor of the controllable switch in a manner tending to minimize any difference between actual and commanded currents. The control system further includes apparatus for changing the repetition rate of the current pulses in response to the magnitude of current in the motor, without effecting the commanded duty factor of the controllable switch, so that the ripple currents which are inversely related to repetition rate are reduced as average motor current is increased to thereby maintain total peak current levels within predetermined limits.

Abstract: Method and apparatus for effecting control of a complementary impulse commutated inverter to enable start-stop operation without power removal and to avoid start-up failures caused by inductive load flux saturation. The invention utilizes a gating logic circuit to always start inverter operation by gating a first predetermined switching element. The gating logic circuit responds to a stop command by terminating operation in a half-cycle in which the first predetermined switching element is not carrying load circuit. In one embodiment upon receipt of a stop command the gating logic circuit terminates inverter operation by applying a last gating signal to the first predetermined switching element, the last gating signal having a time duration less than that required after receipt of a gating signal for current reversal in the inductive load.

Abstract: Apparatus for limiting the peak magnitude of voltage applied to a chopper excited load to the magnitude of the source voltage. In a system including a chopper, a smoothing reactor and a load serially connected to a direct current power source, a clamping circuit is connected in parallel with the chopper and smoothing reactor and provides a current path between the load and the direct current source when load voltage attempts to exceed source voltage as a result of commutation transients in the voltage-turn-off chopper. Where the load is a direct current motor, the clamping circuit in combination with a freewheeling diode provides a suppression circuit for power source transients.