Abstract: A parallel running control apparatus for two PWM inverters includes a first and a second electric current detector for detecting AC output electric current of the PWM inverters; a first and a second electric current control circuit for outputting, on the basis of the output electric current, three-phase voltage command values of the corresponding inverters; and a first and a second pulse generating circuit for outputting, on the basis of the three-phase voltage command values, command pulses which controllably turn on and off the corresponding inverters.

Abstract: An active damper for an L-C filter suppresses transients that appear on the DC link from a power supply. The damper suppresses the transients by filtering the line voltage to obtain its steady-state component and comparing the steady-state voltage to the instantaneous voltage on the DC link. When the two voltages differ, the active damper cancels the transient by dissipating the energy on the DC link and the energy stored in the filter's inductor.

Abstract: A digital voltage protection circuit (138) and a phase monitor circuit (154, 160, 162, 168) disconnect AC-powered user equipment (22,182) from the AC power supply (141) whenever the AC power line voltage is outside a predetermined operating voltage window and when any two phases of the power supply (141) are separated by more than a predetermined phase angle. The user equipment (182) is automatically reconnected to the power supply (141) only after the power line voltage and phase remain continuously within operating range for a predetermined delay period. The voltage monitor (138) contains a digital comparator (18) that uses integrated circuit digital logic thresholds as reference voltages for setting upper and lower voltage window limits. The controller protects the user equipment from both over-voltage and under-voltage (brownout) conditions and from phase errors.

Abstract: A bipolar power supply capable of selectably supplying either a positive or a negative voltage at an output terminal. The power supply comprises a first operational amplifier, a second operational amplifier, a first transistor electrically connected to a positive voltage source and a second transistor electrically connected to a negative voltage source. The first transistor is electrically connected to the first operational amplifier and the second transistor is electrically connected to the second operational amplifier so that the first and second amplifiers control the operation of the first and second transistors respectively. The inputs of the first and second operational amplifiers are electrically connected in a manner that prevents them from simultaneously providing large positive voltages at their outputs.

Abstract: A synchronizing current regulator whose clock frequency is able to be readjusted is provided in the case of a circuit configuration for the synchronized supply of an electromagnetic user with regulation which is acted upon by a control signal representing the difference between the instantaneous signal at the user and a predeterminable reference signal.

Abstract: A current detection method for a direct-current (DC) to three-phase alternating-current (AC) converter can utilize only a single DC sensor to detect and calculate the three-phase alternating currents. The method can detect a direct current value of one phase at each of six different gate states of three pairs of transistors in the DC to three-phase AC converter by means of the DC sensor. In the two-level pulsewidth modulation control, the control signal includes a plurality of carrier periods each being subdivided into three intervals. The three pairs of transistors are switched to the zero state in one interval of each carrier period, and to two different gate states respectively in the two other intervals. The method can detect two current values of different phases respectively in the two other intervals of each carrier period, and then calculate the current value of the other phase in accordance with the principle that the sum of the three-phase currents is always equal to zero.

Abstract: A power system control apparatus has a power system impedance estimating circuit for estimating a power system impedance from an internal power of a generator, determined by an internal current thereof, and from a terminal voltage of the generator, and having a power system impedance estimating table, a power system stabilizer for suppressing a power fluctuation in power system in accordance with the estimated power system impedance, and an auto voltage regulator for keeping an output voltage of the generator at a constant value during a normal operation.

Abstract: The invention relates to a regulated DC power supply circuit comprising a full wave rectification stage for rectifying an AC input and a regulating stage for regulating an output voltage from the rectification stage. The regulating stage has a primary voltage regulating circuit and a secondary voltage regulating circuit. The primary voltage regulating circuit includes a series pass element, such as a MOSFET device, connected to operate continuously in source-follower mode. A primary voltage reference element, such as a zener diode, provides a gate reference for the series pass element. The secondary voltage regulating circuit is cascaded to the primary voltage regulating circuit in a voltage sharing configuration. The power supply circuit is therefore capable of handling input voltages over 1 kV, which exceed the maximum voltage rating of the MOSFET device. The invention extends to a DC voltage regulator, which includes the regulating stage without the rectification stage.

Abstract: A method and a switching arrangement are provided for regulating a two-dimensional vector of a controlled system with a discrete value final controlling element having a limited switching frequency. The discrete value final controlling element also has limited number of actual-value vectors. A switching arrangement, such as a microprocessor, receives actual values for the two-dimensional vector as well as a reference vector and selects three actual-value vectors that are adjacent to the reference vector. The switching arrangement generates a reference trajectory which represents a sequence of vector settings for the discrete value final controlling element. A switch from one actual-value vector to another takes place when the distance between the two-dimensional vector and a next corner point of the reference trajectory is at a minimum. The resulting mean value of the generated two-dimensional vector is equal to the reference vector.

Abstract: A resonant type switching power source implementing zero voltage switching on the basis of the resonance between an inductor and a capacitor. A main switch is connected to the primary side of a main transformer. A pulse width control circuit generates a control signal for varying the turn-on time of the main switch until the output voltage of the secondary side of the tranformer being fed back reaches a predetermined value. A resonance capacitor is connected in parallel with the main switch. When the terminal voltage of the capacitor crosses zero potential toward the negative side, the pulse width control circuit delivers an ON command to the main switch. Alternatively, the ON control over the main switch may begin at a time a predetermined period of time later than the time for turning on the resonant circuit.

Abstract: The generator of reference voltage comprises a first current generator suitable for generating a current that varies linearly with the supply voltage, a first voltage generator suitable for generating a constant voltage with zero thermal drift, a second current generator suitable for generating a current dependent on the voltage with zero thermal drift, a second voltage generator suitable for generating a voltage with given thermal drift, a third current generator suitable for generating a current dependent on the voltage with given thermal drift and means for combining the three currents together so as to produce across an output resistance an output voltage having a value equal to the product of the output resistance by the first and third current, divided by the second current.

Abstract: An MOS voltage-controlled resistor is disclosed. The voltage-controlled resistor comprises a first triode MOSFET, a second triode MOSFET, and a single diode connected MOSFET. The single diode connected MOSFET is coupled in series with the first triode MOSFET. These two MOSFETs in series, are in turn, coupled in parallel with the second triode MOSFET. A control voltage, V.sub.CONTROL, is applied from the gates to the sources of the first and second triode MOSFETs. A voltage-controlled resistance can then be measured between the two nodes defining the parallel coupling of, the single diode connected MOSFET in series with the first triode MOSFET, with the second triode MOSFET.

Abstract: In one embodiment, a solid state DC power supply includes an inverter (30) having two half-bridges (32, 34) in which are provided pairs of MOSFETS (Q5-Q12) used as switching elements. An output transformer (60) and a rectifier (85) are connected to output terminals (T60). A feedback path includes switching control means (40) separate primary and secondary drive means (10, 20) supplying drive pulses to the switching means (Q5-Q12) in the inverter (30). The secondary drive means (12, 13) amplifies the pulse output of the primary drive means (11) in order to improve the switching speed of the inverter (30). Current detection is provided by a transformer (70) connected to switching (40). The primary and secondary drive means receive pulses from a pulse width modulator (IC5) the output of which is isolated by transformers (TX1, TX2). In a modification, a power converter in the form of a DC power supply includes parallel MOSFET (M) and IGBT (I) switch pairs in each arm of a full wave bridge configuration.

Abstract: A scheme for counteracting subsynchronous resonance in an AC power system that comprises a passive device in combination with a line inductive shunt reactor (L10). The device is connected from the neutral end (N) of the reactor (L10) to ground and comprises a plurality of circuit branches: one of those branches comprises a condenser (C10), another one includes an inductor (L12) in series with at least one tank circuit (C14, L14). The combination of these elements results in circuit paths from the AC line to ground of selected admittance values for at least one selected frequency as well as in a solid grounding of the shunt reactor neutral at synchronous frequency.

Abstract: An auto-TC voltage reference wherein an operational amplifier receives at one input the voltage of a Zener diode and at its other input receives a compensation signal from a feedback circuit comprising a transistor and resistor network. When one of the resistors of the network is trimmed to give a nominal output voltage for the reference, the TC of the reference voltage will have been reduced to zero, or nearly so. The circuitry is capable of compensating Zener diodes of either positive or negative TC.

Abstract: Disclosed is a current mirror which maintains good performance when the current to be tracked corresponds to a voltage close to the low supply voltage. This current mirror includes a feedback circuit which causes the first transistor of the reference branch of the mirror to track the voltage of the second transistor of the output branch of the mirror.

Abstract: A semiconductor integrated circuit unit, suitable for the control of a motor, has an integrated structure within the same semiconductor substrate, comprising an inverter circuit, drive circuits for driving the switching elements of the inverter circuit, an internal power source circuit for supplying power to the drive circuits which drive the upper arm side of the inverter circuit, and a logical circuit for transmitting a signal to the drive circuits which drive the upper arm side of the inverter circuit.

Abstract: A battery charger for charging a battery from a DC source includes a step-down convertor coupled to the battery and to a voltage source. When the voltage required to charge the battery is less than that of the DC source, the step-down convertor is connected directly to the source and if the source voltage is less than that required to charge the battery, a step-up convertor is connected between the source and the step-down convertor. Control circuits are provided for sensing the presence of a battery pack, for initiating the flow of charging current, for pulse-width modulating the flow of charging current to the battery and for terminating the flow of charging current when the battery is fully charged as sensed by a predetermined battery temperature or a predetermined drop in battery charging voltage from a peak value. A timer or a latching circuit prevents the resumption of charging current flow until the battery being charged has been removed or replaced.

Abstract: Dead time circuitry for ensuring that no two switching devices in a half-bridge, or in the same leg of a full-bridge, are conductive simultaneously employs a symmetrical delay circuit which independently delays the rising and falling edges of each signal pulse.

Abstract: A switching power supply having an overcurrent protective circuit which includes a detection resistor for detecting the primary current of a transformer to produce a detected voltage, a reference voltage circuit for producing a reference voltage, and an amplifier. The amplifier produces an overcurrent protective signal when the detected voltage exceeds the reference voltage, and supplies the overcurrent protective signal to the control terminal of a switching device which switches the primary current so that a drive signal for the switching device is decreased when an overcurrent of the secondary current occurs. The overcurrent is limited to a value equal to or less than the rated current of the switching power supply without an instantaneous interruption of the power.