Abstract: To maintain a defined three-phase voltage system at the output terminals of a transformer device TE, for example, a transformer in a delta/wye connection where the primary-side neutral point is unconnected, even when an asymmetrical load is connected to it and to the secondary-side neutral point, single-phase transformers are used, whose primary windings are supplied with voltage by a pulse-width modulated, three-phase invertor in a bridge connection. Through the use of voltage regulators, the actual values of the secondary-side line voltages form the control voltages for each bridge-arm pair. The closed-loop control circuits of the three phase voltages are broken down in accordance with the structure of the transformer device by means of a break-down element. The setpoint values can be calibrated to a synchronizing voltage, and/or a current control for the conductor currents is superposed on the voltage regulators.

Abstract: This invention relates to a bus configuration for a dual channel variable speed constant frequency motor/generator aircraft power system providing for both power generation and engine starting. The subject invention provides for isolation of faults which can occur in long power feeders. Further, the subject invention provides for a novel start mode of operation which allows one channel to provide power to the other channel, thereby avoiding inefficient multiple converter operation and potentially faulty power buses. The bus configuration provides for coupling a first motor/generator to a second motor/generator via a first converter to thereby allow th first motor/generator, operating as a generator, to supply variable frequency power to the first converter, the first converter supplying variable frequency power to the second motor/generator to operate the second motor/generator as a motor.

Abstract: In a system interconnecting inverter apparatus, an inverter for controlling power of an AC power system is coupled, via a coupling reactor, to the AC power system having a system voltage. A system phase signal indicating the phase of the system voltage is detected by a system phase detection circuit in real time. Another phase signal indicating the phase of the system voltage is detected by a comparison phase detection circuit with a predetermined delay time, and the detection result is temporarily stored in the circuit as a comparison phase signal. The system phase signal and the comparison phase signal are phase-compared by a stop circuit. When a phase difference between the system phase signal and the comparison phase signal exceeds a predetermined value, the stop circuit stops the operation of the inverter.

Abstract: A transmission line between terminals of a three-terminal station is branched by a branching unit and power is transmitted between the terminals of the three-terminal station and a power feed system in the transmission line including: a switch for switching a power feed line feeding power to a repeater between a both-end power feed mode and a single-end power feed mode; and connection holding means for holding a power feed connection state without change upon an occurrence of a failure.

Abstract: An improved DC-AC converting arrangement for a photovoltaic system, which makes it possible to supply power at high efficiency by providing a driving control system arranged to stop operation of a DC-AC converter when a load power of the DC-AC converter falls below a predetermined reference value, and to restart the operation of the DC-AC converter when the load power exceeds the predetermined reference value.

Abstract: A transistor is operated in the PWM mode such that a hlaf sine wave of current is delivered first to one-half of a distribution transformer and then the other as determined by steering thyristors operated at the fundamental sinusoidal frequency. Power to the transistor is supplied by a dc source such as a solar array and the power is converted such that a sinusoidal current is injected into a utility at near unity power factor.

Abstract: Control units are provided associative with forward and inverse converters in a multiterminal DC power transmission system, respectively. The control units set different constant voltages in the converters. Further, the minimum value of the constant voltage set values in the forward converters is set at a value larger than the maximum value of the constant voltage set values in the inverse converters.

Abstract: A synchronous inverter combines direct current energy from a minor source, such as a wind driven generator, with alterneting current energy from a commercial power source, in a home electrical distribution system. This inverter uses a linear audio amplifier to produce an alternating current voltage that is continuously essentially the same as the commerical power voltage in voltage wave shape, amplitude, phase and frequency. The amplifier energy level output is controlled by the voltage level from the minor energy source. The compatibility of the inverter with commercial power permits connection of the inverter by merely plugging its power cord male plug into a selected home electrical distribution system female receptacle.

Abstract: An uninterruptible power supply includes a digital control circuit to control the transfer of power from a primary and a secondary power source to a load circuit to be energized. The digital control circuit controls through digital techniques the relative phase angles of a primary power signal, a secondary power signal, and a load signal to advantageously minimize the power drain on an idling secondary power source when the primary power source is active and to minimize transients in the load signal when converting from one power source to another.

Abstract: Electrical line voltage energy from an AC power network is combined with the energy derived from an auxiliary DC voltage source through the primary winding of a transformer to operate an AC load under rated conditions normally associated with its operation by the AC power network alone. The DC voltage is converted to a form compatible with said rated operation of the load under control of AC signals sampled from the AC power network. Line voltage from the AC power network to the transformer primary is blocked when sufficient energy is available from the DC voltage source alone to operate the load.

Abstract: A conversion means converts the energy available from a source, such as the wind or sun, into a corresponding amount of d.c. electrical power. A switching circuit, typically a thyristor bridge, is connected between the conversion means and an a.c. load and across a.c. power mains energizing the load. The switching circuit is operable to periodically connect the conversion means to the a.c. load in a power supplying manner. The a.c. mains impart suitable voltage and frequency characteristics to the electrical power so supplied. In the event the supplied power exceeds the power required by the a.c. load, the difference is taken by the a.c. power mains.

Abstract: A DC to DC converter which gives two individually controlled and stabilized DC voltages includes an oscillator of the push-pull type and two rectifiers which are connected to the output of the oscillator. The transformer of the oscillator has a primary winding which has been split up in two halves, the end of each half being connected to a controlling DC voltage. The secondary winding of the oscillator transformer has its one end connected to the two rectifiers. The output of each of the rectifiers is connected to one input of a regulating circuit, the output of which is connected to each of the primary winding halves for delivering the controlling DC voltage.