Abstract: An AC/DC converter system comprises an input circuit for connection to a three-phase AC source. An isolation transformer comprises a symmetrical core with a set of primary windings and first and second sets of secondary windings wound on the symmetrical core providing balanced flux in all three phases and magnetically coupling to the set of primary windings. The first and second sets of secondary windings are phase shifted by select amounts from the set of primary windings. The set of primary windings is connected to the input circuit. An AC/DC converter comprises first, second and third three-phase rectifiers, the first three-phase rectifier is powered by the first set of secondary windings, the second three-phase rectifier is powered by the second set of secondary windings, and the third three-phase rectifier is powered by the input circuit. An output circuit is connected between the AC/DC converter and a DC load.

Abstract: A system and process includes continuously determining an applied armature voltage supplied to a polyphase synchronous machine for which a maximum mechanical load is characterized by a pull-out torque. The armature voltage is supplied from a power source via one of many taps of a regulating transformer. The armature voltage being supplied from the power source to the machine is changed by selecting one of the voltage levels from the taps of the regulating transformer. The tap voltage levels are selected based on the determined applied armature voltage to minimize power consumption of the machine while ensuring based on a predetermined confidence level that the pull-out torque of the machine will not be exceeded.

Abstract: An adjustable frequency drive includes a base having a first portion and a second portion, and an active front end converter disposed on the base. The converter includes an input, an output, and a plurality of first electronic switches electrically connected between the input and the output. An inverter is disposed on the base and includes an input electrically connected to the output of the active front end converter, an output, a plurality of capacitors disposed on the first portion of the base and electrically connected to the input of the inverter, a plurality of second electronic switches disposed on the second portion of the base and electrically connected between the input and the output of the inverter, and a heat pipe assembly. The inverter is structured to provide a single, three-phase output structure.

Abstract: An electric compressor control device includes: an inverter for electric compressor motor; a communication microcontroller arranged in a low-voltage region for transmission of an instruction signal via a high-speed communication bus; and a control microcontroller arranged in a high-voltage region and connected to the communication microcontroller via an insulation element for transmitting the instruction signal from the communication microcomputer as an inverter control signal to the inverter. The power voltage of the communication microcomputer is supplied from a low-voltage power source. The voltage from the low-voltage power source is transformed via a transformer and supplied as a power voltage of the control microcontroller.

Abstract: A sensorless induction motor control device with a function of correcting a slip frequency wherein a slip frequency estimation unit estimates the slip frequency from at least one kind of current flowing through the motor. A voltage command value calculation unit calculates a D-phase voltage command value and a Q-phase voltage command value which are used for controlling a voltage applied to the motor using a Q-phase current command value calculated based on a difference between a speed estimation value, which is calculated using an estimation value of the slip frequency, and an externally supplied speed command value. An ideal voltage command value determination unit determines an ideal voltage command value using the speed command value and the Q-phase current command value. An actual voltage command value calculation unit calculates an actual voltage command value using the D-phase voltage command value and the Q-phase voltage command value.

Abstract: A method and apparatus comprises a filter receiving an input voltage signal from a drive circuit, and a filter producing an output voltage signal with reduced resonance and transients. The amplitude of the output voltage signal is boosted using the filter.

Abstract: An apparatus (10) for controlling the starting and stopping of an AC induction motor, the apparatus (10) comprising: a first magnetic permeable portion (20) having first (21), second (22) and third legs (23); a second magnetic permeable portion (40) arranged relative to the first magnetic permeable portion (20) such that a magnetic control flux of the second magnetic permeable portion (40) has an opposite magnetic polarity to a magnetic control flux of the first magnetic permeable portion (20), the second magnetic permeable portion (40) having fourth (41), fifth (42) and sixth legs (43); a non-magnetic spacer (3) separating the first and second magnetic permeable portions (20, 40) to prevent magnetic control flux cancellation between the first and second magnetic permeable portions (20, 40); a first AC power phase winding (90) wound around the first and fourth legs (21, 41); a second AC power phase winding (100) wound around the third and sixth legs (23, 43); a first pair of DC excitation control windings (70

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may include receiving shunt current in one or more conductors according to a sensed component of power distributed by the conductors through one or more transformers coupled to the conductors and determined by an inductance associated with the transformers and a capacitance associated with the conductors.

Abstract: A method of starting and apparatus for starting a multiphase electrical machine is disclosed. The aim is to reduce oscillatory pulsation in torque generated by the motor and inrush current that occurs shortly after start-up. The starting method comprises the steps of first connecting at least one, but less than all, of a plurality of windings to a respective phase-shifted supply voltage at a controlled point in the supply phase. Then, after a controlled delay following the connection made in step i., connecting the or each remaining winding of the machine a respective phase-shifted supply voltage. The invention has particular application to multiphase (most usually, 3-phase) motors. However, it can also be applied to other electrical machines, such as generators and transformers. The method can be performed at initial start-up or, in the case of application to a motor, at Y-delta switchover. On reconnection of a load generating a significant back-e.m.f., the 2-step process is initiated when the back-e.m.f.

Abstract: An inverter device capable of smoothly driving an alternating current synchronous motor of large capacity and high-speed rotation is provided. The inverter device includes a power rectification main circuit for converting alternating current power into direct current power and a PWM control inverse transformation main circuit. A transformer raises output terminal of the alternating current power of the inverse transformation main circuit to drive an alternating current synchronous motor. The alternating current motor is started bypassing the transformer and limiting output voltage of the inverse transformation main circuit to a low value through PWM control of the inverse transformation main circuit.

Abstract: A coil winding number variable type motor for varying a cooling and heating capacity of a reciprocating motor includes: a plurality of coils separately wound and connected in series to each other so as to vary turn ratio among motor coils; a plurality of relays respectively connected between adjacent coils among the plurality of coils; and a relay controller for outputting and ON/OFF control signal for varying the winding number of the motor coil and controlling the relays according to a change in a load and a power supply voltage. The coil wound in the motor of the reciprocating compressor is divided into the main coil and the plurality of sub-coils and the winding number of the motor coil is varied by itself to control the stroke of the reciprocating compressor, thereby effectively coping with the change in the voltage or the load.

Abstract: A method and apparatus for monitoring a three-phase electric motor which has been disconnected from the electrical mains and is running down, one phase of the voltage generated by the motor being checked respectively in each of two channels for zero crossings and, if a zero crossing occurs, a signal being produced which, after DC-decoupling, is used to control the operation of a safety device. The safety devices are mutually interlocked and control signals therefor are produced only when the period between zero-crossings detected in both channels indicates that the motor output shaft has ceased rotation.

Abstract: A motor is supplied with electricity across a transformer (T) which outputs on a busbar (J) which is connected to the motor (M) and to other electrical energy consuming devices, the motor by itself consuming an active power greater than or equal to 20% of the available electric power. During at least a part of the starting period of the motor, the motor is supplied with reduced voltages taken on intermediate taps (P.sub.1, P.sub.2, P.sub.3) in the secondary windings of the transformer (T).

Abstract: The present invention is applicable to any a.c. electromagnetic reduction device which is used to change voltage or current levels or to transfer energy between mechanical and electrical systems and includes, for each phase, a combined pair of windings which are conductively and inductively dependent. The dominant winding of each combined pair is electrically connected to an input/output phase, while the reflux winding of each pair is electrically connected in additive or subtractive series with the dominant winding by means of a variable capacitive reactance. The capacitive reactance is then adjusted to minimize the net reactive factor of the coupled windings and the net reflected impedance of the input/output circuitry.

Abstract: A multiphase load control system has switches in electrical series within each of several split sources of phase voltage. In each phase of one implementation, two contactor poles are in series between split sections of a secondary winding of a transformer. The contactor poles are part of one or more contactor units, each of which can have a voltage rating significantly less than the phase voltage provided by the system.

Abstract: An ac drive in which the three phase ac current produced by a current controlled inverter is applied to the stator winding of a synchronous or induction motor through an autotransformer equipped with a neutral shorting switch. For starting from zero speed and operation at very low speeds below the speed at which the autotransformer could provide adequate volt-seconds for operation of the motor, the neutral shorting switch is opened so that the current is applied essentially directly to the stator. At normal and high speeds, the neutral shorting switch is closed so that the voltage to the motor stator is increased by the turns ratio of the autotransformer thereby increasing the speed range of the motor. By providing a number of sets of taps on the autotransformer each with a neutral shorting switch, the ac drive mimics the characteristics of a drive with a multi-ratio gear box.

Abstract: An apparatus and method for accelerating textile winder synchronous motor drives from standstill to rated running speed wherein a synchronous motor is first accelerated asynchronously to a first intermediate speed, then decelerated to and synchronized at a second intermediate speed, then accelerated synchronously to rated speed, while thereby limiting current drawn by the motor to levels not exceeding rated current. The method is automatically followed using apparatus which varies motor input frequency responsive to a predetermined sequence of control signals supplied from a signal source via a transient response profiler which converts sudden changes in signal strength to smooth, gradual changes. As more specifically described herein, only two controllers are needed, and a switching network including time-delay devices selectively supplies one signal or the other via an integrator to a variable frequency converter.

Abstract: Low voltage starting of a three-phase submersible pump motor in a shallow well is achieved by employing a high-impedance transformer for supplying the three-phase power to the motor. Upon starting, the normally heavy current drawn by the motor results in a voltage drop through the high-impedance transformer sufficient to substantially lower the voltage across the motor and hence the starting current. In the absence of limiting the starting current, abnormally high starting torques will be produced on the motor shaft resulting in mechanical fatigue and eventually shaft breakage.

Abstract: An improved apparatus for an automatic full voltage start of a polyphase synchronous or induction motor. A full line voltage is employed to start the motor by energizing two tap relays to shunt the tap connections of the coils of an autotransformer and to thereby apply a line voltage to the primary windings of the motor. A strap relay is de-energized to disconnect the coils of the autotransformer when the motor is at rest and when the motor is being started. After the motor is started, the tap relays are de-energized to break the shunt connections and the strap relay is energized to connect the coils of the autotransformer. The taps of the autotransformer apply a preset reduced voltage to operate the motor.