Abstract: A power tool includes a tool housing, an electric motor inside the housing, and a power interface facilitating a connection to a power source. At least four actively-controlled power components are configured as an H-bridge to modulate a supply of power from the power interface to the electric motor. A user-actuated input unit outputs a first signal indicative of a desired power output level to the electric motor and a second signal indicative of a desired direction of current flow to the electric motor. A control unit controls the supply of power to the electric motor using two of said power components with synchronous rectification for pulse-width modulation (PWM) of the supply of power based on the first signal, and to control the direction of current flow to the electric motor using the other two of said power components based on the second signal.

Abstract: A method is disclosed for operating a two-phase rotary current controller. In order to optimize the operation of a two-phase rotary current controller, magnitudes of a parameter that can be varied in both controllable phases of a two-phase rotary current controller is matched in these phases. In particular, the existing principle of phase-symmetric control with a uniform ignition delay in both controlled outer conductors is abandoned, and a separate ignition delay is stipulated for each of the two controlled outer conductors.

Abstract: A fault detection and inhibit circuit for a power control unit in an electric traction motor propelled vehicle of the type wherein the power control unit includes a chopper circuit and a bypass contactor for shunting the chopper circuit when its percent conduction exceeds a relatively high value and a main contactor for connecting the chopper circuit and motor to a power source. The circuit assures that neither the main contactor, the bypass contactor nor the chopper circuit are in a shorted condition before permitting the application of power to the system. In the event of a running failure, the circuit prevents restarting until the failed condition has recovered.

Abstract: An elevator system of the traction type having a direct current drive motor and a solid-state, dual-bridge converter power supply. Protective and monitoring apparatus reduce the probability of fuse blowing due to improper gating of a controlled rectifier device, and/or a power supply interruption, while enabling the system to override longer power supply interruptions without initiating shutdown in certain instances. The deceleration range of the elevator car is narrowed, when an orderly shutdown is required, by sensing predetermined parameters of the elevator system and logically selecting the value of a dynamic braking resistance in response thereto.

Abstract: A system, for supplying electrical power from a source to a load, of the type employing phase controlled rectifiers for controlling the power from a polyphase source to the load includes circuitry to detect the existence of a rectifier which is conducting at an improper time and to provide appropriate corrective action to terminate such improper conduction.

Abstract: A power converter system for converting an AC voltage into a DC voltage, comprising a transformer means provided with a primary winding connected to an AC power source and a secondary winding divided into a plurality of sets of coils; and rectifier means including a plurality of rectifier circuits, each of said rectifier circuits including controlled rectifier elements and having AC and DC terminals, said AC terminals of each rectifier circuit being connected to the corresponding one of the sets of secondary coils, said DC terminals of said respective rectifier circuits being connected in series to produce a DC output voltage from said rectifier means, a predetermined one of said rectifier circuits being adapted to control its DC output voltage sequentially and cyclically in a plurality of steps of generating the DC output voltage from said rectifier means, the remaining rectifier circuits being adapted to control their DC output voltages in an on-off fashion in said steps, said steps being switched over by o

Abstract: A motor control system of the type employing phase controlled rectifiers for controlling the power supplied from a polyphase alternating current source to a direct current motor includes circuitry to detect the existence of a rectifier which is conducting at an improper time and to provide appropriate corrective action to terminate such improper conduction.

Abstract: A power converter which can operate with both a D.C. power source and an A.C. power source for supplying electric power to a D.C. load such as a D.C. motor. The power converter comprises thyristors, a diode, a reactor and a capacitor. A plurality of series circuits each including two series-connected thyristors are connected in parallel to provide A.C. terminals at the series connection points of the thyristors and to provide D.C. terminals at the parallel connection points of the series circuits. The diode is interposed between the parallel-connected series circuits of the thyristors, and the reactor and the capacitor are connected in series to form a series circuit which is connected in parallel with the series circuits of the thyristors. The power converter is connected at the D.C. terminals between the power source and the load to function as a chopper when the power source supplies D.C. power to the load. On the other hand, when the power source supplies A.C.