Abstract: A modular multilevel converter system. The system includes a plurality of series connected two-terminal M2LC cells arranged into at least two output phase modules. A first one of the output phase modules has an inductance and an effective capacitance associated therewith. The first one of the output phase modules is configured so that a natural resonant frequency of the inductance with the effective capacitance of the first one of the output phase modules is greater than at least one of the following: an operating frequency of the first one of the output phase modules; a switching frequency of the first one of the output phase modules; and a switching frequency of any of the M2LC cells of the first one of the output phase modules.

Abstract: A polyphase AC induction motor is connected to a power supply through a soft starter having three sets of inverse parallel connected silicon controlled rectifiers with each set corresponding to one particular phase. Low speed starting and operation of the motor can be accomplished through triggering circuits controlling the phases of the triggering pulses in relation to the phases of the supply. The low motor speeds are developed by a gating sequence that generates a low frequency waveform that is less than the main supply frequency to the motor. This low frequency waveform is current and voltage controlled by the gating sequence to permit the AC motor to smoothly operate at speeds less than 100% of rated while developing net positive torque at the low controlled operating frequency.

Abstract: A solid state motor starter assembly having controlled semiconductors mounted between heat sink members. Electrical power to the assembly can be connected an disconnected by an electrically operated solenoid that actuates a movable contact into engagement with a stationary contact mounted on the incoming heat sink. To reduce the heat generated in the semiconductor device during steady state full voltage operation, a shunting current path is established between the adjacent heat sinks by an electrically operated solenoid which moves a movable contact bar to engage stationary contact surfaces mounted directly on the heat sinks. Electrically joining the incoming line heat sink to the outgoing heat sink provides a low resistance parallel current path around the semiconductor thereby reducing the heat generated in the assembly during full voltage operation. The above contacts and solenoids can be directly mounted to a heat sink assembly thereby providing the benefits of unitized construction.