Abstract: In some embodiments, an inverter control apparatus and a method for controlling the same are provided. The inverter control apparatus may speed up the discharging of the residual energy at an inverter driven with an input power when a safety signal is input to the inverter. The inverter control apparatus may include an input power switchgear supplying an input power to the inverter according to switching operation; an I/O unit inputting a safety signal to the inverter according to a user control input and outputting a failure output relay signal to the input power switchgear when the safety signal is generated; and a controller performing speeding up the discharge of residual energy at the inverter when the input power is interrupted.

Abstract: Provided are a system and a method for controlling a frequency. The system for controlling the frequency includes: at least one power supplying unit generating power; at least one systematic unit consuming the power generated from the power supplying unit; at least one standby power unit storing the power generated from the power supplying unit and including at least one storage device; and at least one grid unit connecting the power supplying unit, the systematic unit, and the standby power unit to one another and controlling a frequency of the systematic unit.

Abstract: A power conversion apparatus 1 according to an embodiment of the present invention includes a high-voltage side input terminal TIH and a low-voltage side input terminal TIL, first and second output terminals TO1 and TO2, a power conversion circuit 10 that converts direct-current power input between the high-voltage side input terminal TIH and the low-voltage side input terminal TIL to generate alternating-current power between the first and second output terminals TO1 and TO2, and an inverted-voltage generation circuit 30 that generates an inverted voltage of a common mode voltage generated between the first and second output terminals TO1 and TO2 and inputs the inverted voltage to the low-voltage side input terminal TIL.

Abstract: A method for reducing the common mode current (i) circulating between the internal ground (13) of an electrical circuit (4) and the earth when electrical energy is exchanged between an electrical energy storage unit of the electrical circuit (4) and an electrical energy source external to said circuit (4), in which method an electronic component (21) is used to apply an electrical quantity (Vs, Is) at a point (26) connected via at least one impedance (28) to an electrical line (5) of said circuit (4) via which electrical energy is exchanged, said electrical quantity (Vs, Is) applied making it possible to reduce the common mode current (i).

Abstract: A power supply includes power modules. Each of the power modules includes an input stage and an output stage. The input stage generates an intermediate voltage, and the output stage outputs a DC supply voltage according to the intermediate voltage. The input stages are controlled with at least one first common control signal having a common duty cycle, and the output stages are controlled with at least one second common control signal having a common duty cycle.

Abstract: A sub-sea power supply includes a plurality of transformers, a wet-mateable connector, and a plurality of passive rectifier circuits. Each transformer includes a primary coil and secondary coil. The primary coils are coupled in parallel. The wet-mateable connector is coupleable to a sub-sea AC power source. The wet-mateable connector is coupled to the primary coils. The plurality of passive rectifier circuits is respectively coupled to the secondary coils. The plurality of passive rectifier circuits is configured to generate substantially uniform polarity voltage outputs coupled in series.

Abstract: This relates to systems and processes for programming parameters of a controller of a power converter. In one example, a predetermined signal may be applied to the input or output terminals of the power converter to unlock the controller and cause the controller to enter a programming mode. While in the programming mode, one or more additional predetermined signals may be applied to the terminals of the power converter to program one or more parameters of the controller. Once the desired parameters have been programmed, another predetermined signal may be applied to the terminals of the power converter to cause the controller to exit the programming mode and enter a locked mode. The predetermined signals applied to the terminals of the power converter can include an ac or dc signal having a predetermined pattern of changes in frequency, amplitude, and/or magnitude that are applied for a fixed or variable duration.

Abstract: In a marine power distribution and propulsion system with a medium voltage distribution busbar (MVAC1) and a low voltage distribution busbar (LVAC1) then a rectifier (SC) is controlled, optionally to provide active filtering and static compensation benefits. A common power supply system incorporating ac generators (G1-G4) supplies power to the medium and low voltage distribution busbars. The rectifier (SC) is connected to the medium voltage distribution busbar (MVAC1). A controller (Co) uses feedback signals indicative of electrical quantities of the distribution voltages carried by both the medium voltage and low voltage distribution busbars (MVAC1, LVAC1) to control the rectifier (SC) to regulate electrical quantities at the ac terminals of the rectifier (SC) in order to achieve desired electrical quantities of the distribution voltage carried by the low voltage distribution busbar (LVAC1).

Abstract: A hybrid power plant is characterized by a substantially constant load on generators regardless of momentary swings in power load. Short changes in power load are accommodated by DC components such as capacitors, batteries, resistors, or a combination thereof. Resistors are used to consume power when loads in the power plant are generating excess power. Capacitors are used to store and deliver power when the loads in the power plant demand additional power. Reducing rapid changes in power load as seen by the generators allows the generators to operate at higher efficiencies and with reduced emissions. Additionally, power plants employing combinations of generators, loads, and energy storage devices have increased dynamic performance.

Abstract: Provided are a power cycle test apparatus and a power cycle test method that can efficiently reproduce nearly a level of stress that may occur in failure mode in actual environments, the apparatus which is a test apparatus for performing a power cycle test for a power semiconductor device to be tested by applying a thermal stress to the power semiconductor device through the application of a stress current thereto in predefined ON/OFF cycles executes a thermal cycle test in temperature rise-fall cycles longer than the ON/OFF cycles by using an apparatus configured to change an external environmental temperature and further executes the power cycle test while executing the thermal cycle test in synchronization with execution phases of the thermal cycle test.

Abstract: A multi-function power regulator for prioritizing functions and allocating resources thereof, the multi-function regulator including a plurality of resources each having a resource capacity limit. The multi-function regulator also includes a shunt converter is configured to perform one or more shunt converter functions while consuming one or more of the resources, a series converter is configured to perform one or more series converter functions while consuming one or more of the resources. A control engine coupled to the shunt converter, the series converter, and a plurality of sensors, the control engine is configured to monitor and control the one or more shunt converter functions and the one or more series converter functions.

Abstract: A PFC converter (100) is disclosed that includes a voltage rectifier circuit (126, 127, 153) and a voltage regulator circuit (81, 90, 33, 54). The PFC converter (100) also includes an inductor (140) having a plurality of auxiliary windings (141, 142) coupled to the voltage rectifier circuit (126, 27, 153) and the voltage regulator circuit (81, 90,33, 54). One of the auxiliary windings (142) is arranged to supply a start up voltage (V1), during a start up stage, using the voltage rectifier circuit (126, 127, 153) to the voltage regulator circuit (81, 90, 33, 54). Another of the auxiliary windings (141) is arranged to supply a voltage (V1), during a steady-state stage, using the voltage rectifier circuit (126, 127, 153) to the voltage regulator circuit (81, 90, 33, 54).

Abstract: When an AC voltage is outputted to an inductive load, pulsation of an effective power caused by an odd number-th order harmonic component of a current flowing in this load is reduced. A modulation factor k of an inverter 4 includes a DC component k0 and an AC component. The AC component includes a frequency which is a 6n multiple of the fundamental frequency of AC voltages outputted from the inverter. Even when there are not only the 5th order harmonic component of load currents but also the 7th order harmonic component, it is possible to adequately set the ratio of the magnitude of the AC component and the ratio of the DC component and reduce pulsation of consumption power caused by these harmonic components. Reducing the pulsation contributes to suppression of power harmonics.

Abstract: According to an exemplary implementation, an electronic ballast includes an input filter coupled to a resonant tank. The resonant tank is configured to generate a resonant current. The input filter is configured to receive an AC input voltage and to generate an AC input current from the resonant current by smoothing the resonant current. The electronic ballast also includes a half-bridge configured to feed the resonant tank so as to generate the resonant current and to receive a supply voltage that is in phase with the AC input voltage. The electronic ballast can also include a controller configured to control a power factor of the electronic ballast by switching the half-bridge. The controller can be configured to adjust a shape of the AC input current by adjusting switching of the half-bridge to thereby adjust a power factor of the electronic ballast.

Abstract: An energy efficient apparatus includes a switching device, a frequency dependent reactive device, and a control element is provided. The switching device is coupled to a source of electrical power and includes a pair of transistors and is adapted to receive a control signal and to produce an alternating current power signal. The frequency of the alternating current power signal is responsive to the control signal. The frequency dependent reactive device is electrically coupled to the pair of transistors for receiving the alternating current power signal and producing an output power signal. The frequency dependent reactive device is chosen to achieve a desired voltage of the output power signal relative to the frequency of the alternating current power signal. The control element senses an actual voltage of the direct current power signal and modifies the control signal delivered to achieve the desired voltage of the direct current power signal.

Abstract: A method of managing recovery from an event in an electrical circuit leading to a loss of control of an inverter in the electrical circuit is disclosed, the method comprising sampling a parameter of operation before the event, monitoring for occurrence of the event, calculating an estimated value of the parameter at a time after the event based on an extrapolation of the monitored parameter and controlling the inverter using the estimated value of the parameter.

Abstract: An AC/DC converter includes a rectifier circuit and an active power factor correction circuit. The rectifier circuit is electrically connected to a power supply, and is used to convert an alternate current into a direct current, wherein the rectifier circuit has a positive output and a negative output for sending out the direct current. The active power factor correction circuit electrically connects the rectifier circuit and a loading, wherein the active power factor correction circuit is used to suppress voltage ripples provided to the loading.

Abstract: An electrical frequency converter for coupling an electrical power supply grid with an electrical drive includes a first power converter connected to the power supply grid. The first power converter includes at least two connections in series. A second power converter is connected to the electrical drive and includes at least two connections in series. Each of the connections in series of the first and second power converters includes at least two modular switches. Each modular switch includes a first connection in series having a first controllable power semiconductor component and a first diode. The modular switch further includes a second connection in series having a second controllable power semiconductor component and a second diode. The modular switch further includes a capacitor. The first connection in series, the second connection in series and the capacitor are connected in parallel.

Abstract: Systems, methods and apparatus are disclosed for broadband AC to DC conversion. In one aspect, a power conversion apparatus for providing direct current (DC) based at least in part on an alternating current is provided. The power conversion apparatus includes a first rectifier circuit configured to rectify the alternating current to a first direct current. The power conversion apparatus further includes an averaging circuit configured to average the first direct current received from the first rectifier circuit and to provide a second direct current. The power conversion apparatus further includes a second rectifier circuit configured to rectify the alternating current to a third direct current. The direct current is derived from the second direct current and the third direct current.

Abstract: Featured are methods for regulating the AC frequency of the electrical power to be supplied on an electrical distribution system or grid. Such a method includes electrically coupling an energy storage sub-system to the electrical distribution network, where the energy storage sub-system includes one or more flywheel energy storage systems. Also featured as devices, systems and apparatuses embodying such methodologies or for use in implementing such methodologies of the present invention.

Abstract: Systems, methods and apparatus are disclosed for broadband AC to DC conversion. In one aspect, a power conversion apparatus for providing direct current (DC) based at least in part on an alternating current is provided. The power conversion apparatus includes a first rectifier circuit configured to rectify the alternating current to a first direct current. The power conversion apparatus further includes an averaging circuit configured to average the first direct current received from the first rectifier circuit and to provide a second direct current. The power conversion apparatus further includes a second rectifier circuit configured to rectify the alternating current to a third direct current. The direct current is derived from the second direct current and the third direct current.

Abstract: The invention discloses a half-bridge inverter which includes first and second inverter input terminals for receiving a direct current (DC) voltage, first and second inverter switches, first and second drive circuits, and an inverter startup circuit. The first and second drive circuits are adapted to alternatively turn on and turn off the first and second inverter switches, which can convert the DC voltage to a high frequency alternating current (AC) voltage. The inverter startup circuit includes a capacitor, diode, and resistor. The capacitor and diode are connected in parallel and further electrically connected in a drive circuit in series. The resistor is electrically coupled to the first inverter input terminal and to the capacitor/diode parallel combination. The inverter startup circuit is used to trigger the first or second inverter switch. An electronic ballast containing the half-bridge inverter and a lighting device containing said electronic ballast are also disclosed.

Abstract: A wind turbine is provided having a first converter connected between an electric generator of the wind turbine and a DC link and a second converter connected between the DC link and an output of the wind turbine connectable to a utility grid. The wind turbine further includes a wind turbine controller adapted to control at least one of an output current of the wind turbine, an output voltage of the wind turbine, a reactive output power of the wind turbine, an output voltage of the DC link and an output current of the DC link. The wind turbine further includes a communication device adapted to receive a control signal and to set a control parameter of the wind turbine controller in accordance with the control signal. A network converter, method of operating a wind turbine, methods of operating a wind park and computer-readable storage medium are also provided.

Abstract: An image forming apparatus includes an image carrier and the following elements. A charging unit charges the image carrier. An exposure unit exposes the charged image carrier to light and forms an electrostatic latent image. A developing unit generates a developing electric field and develops the electrostatic latent image. A transfer unit transfers the developed image. A controller outputs an AC setting signal. The developing unit includes a bias power supply source having the following elements. An output transformer includes a primary winding and a secondary winding. A switching circuit supplies a current to the primary winding. A current control circuit includes first impedance and second impedance. The first impedance is set when the AC voltage has a first frequency and the second impedance is set when the AC voltage has a second frequency, thereby controlling a current flowing between the primary winding and the switching circuit.

Abstract: A power converting apparatus includes a switching element, a filter substrate, a housing, a main body, an air duct, and a filter switch. The switching element is configured to convert and output power. The filter substrate includes a filter circuit configured to reduce transmission of noise generated in the switching element to an input power source. The housing includes a housing base having a first surface and a second surface. The main body is on the first surface of the housing base, and includes the filter substrate and a plurality of electronic components. The air duct is disposed on the second surface of the housing base, and cooling air flows through the air duct. The filter switch is on the first surface of the housing base. The filter switch is configured to switch between making and breaking electrical conduction between the filter circuit and the housing.

Abstract: Three resonance-based universal power converter topologies are disclosed. One includes a partially resonant parallel L-C link and incorporates intermediate cross-over switching circuits between the link stage and each of the input and output stages (which are constructed using unidirectional switches), thereby permitting the partially resonant circuit to be operated bi-directionally. A second includes a partially resonant series LC link in parallel with the input and output networks. A third includes a partially resonant series LC link in series between the input and output networks. The input and output networks can be formed from either bidirectional switches or a combination of unidirectional switches and intermediate cross-over switching circuits, permitting the partially resonant circuit to be operated bi-directionally.

Abstract: An electricity generating installation includes an electricity generation unit of a gas turbine, steam turbine or combined-cycle type, wherein the electricity generation unit is coupled to a generator and is connected to a distribution network, an energy storage unit configured to store kinetic energy and electrical energy, and a standby electricity generation unit. The installation further includes a controller configured to manage the operation of the energy storage unit and configured to manage the connection of the energy storage unit to the electricity generation unit and to the network. The controller receives a series of information originating from the network, the energy storage unit, the electricity generation unit and a network operator in order to control the generation of electricity to be delivered to the network and to auxiliary systems of the installation from the energy storage unit.

Abstract: A power converter including a rectifier stage connected to plural phases of a network delivering an input current at a determined fundamental frequency, a DC power supply bus and a bus capacitor connected to the DC power supply bus. The converter includes a controlled current source situated on the DC power supply bus, the current source making it possible to control a rectifier current, flowing on the DC power supply bus, and a controller for the controlled current source to control a rectifier current, flowing on the DC power supply bus. The controller is configured to implement a regulation loop into which are injected a first harmonic and a second harmonic synchronized respectively at six times and twelve times the fundamental frequency of the input current delivered by the network, the amplitude and phase of these harmonics being determined to limit the THDi and the PWHD.

Abstract: Optimizes the operation and control of electric generators against events produced in the power grid, such as voltage dips or overvoltages, comprising the following steps: detecting that the DC bus voltage level (Vbus) (301) exceeds the maximum operating limit established in normal conditions; enabling activation permission of the chopper (201); activating the different operating states (304) of the chopper (201) according to the DC bus voltage level (Vbus) (301) and to the current entering the DC bus (Iin.bus) from the generator; detecting that the DC bus voltage level (Vbus) (301) is within the normal operating range; enabling deactivation permission of the chopper (201); deactivating the different operating states (304) of the chopper (201) according to the DC bus voltage level (Vbus) (301) and to the current entering the DC bus (Iin.bus) from the generator.

Abstract: Inverter internal communication features are disclosed. A multiple-stage inverter includes DC to DC and DC to AC converter switches in different power domains, which share no common return path connection. Operating parameters for converter switches in both power domains are determined by a single controller, located in one of the power domains. Converter control signals are communicated from the controller across an interface between the power domains. Respective, separate controllers in each power domain are not required. Components on each side of the interface could be integrated into respective integrated circuits. A planar transformer implemented in wiring levels of a Printed Circuit Board (PCB) that carries components of the inverter could be provided to enable communications between the power domains while reducing component count and physical space requirements.

Abstract: A converter control device comprises: a voltage-zero-cross detection unit detecting zero cross of the alternate-current voltage and outputting a voltage zero-cross signal; a power-source-current detection unit detecting a power source current of the alternate-current power source; a bus-line-voltage detection unit detecting a bus-line voltage between terminals of the smoothing capacitor; a PWM-signal generation unit generating a PWM-signal for on/off-controlling the switching unit, based on the power-source current, the bus-line voltage and a bus-line-voltage command value as a target voltage of the bus-line voltage; a power-source voltage-state detection unit detecting a signal state of the alternate-current voltage based on the voltage zero-cross signal; and a fundamental-switching-frequency selection unit selecting a fundamental switching frequency of the PWM-signal based on the signal state of the alternate-current voltage.

Abstract: Variable frequency motor drives and control techniques are presented in which filter capacitor faults are detected by measuring filter neutral node currents and/or voltages and detecting changes in a frequency component of the measured neutral condition and/or based on input current unbalance.

Abstract: A diode bridge has a pair of input ends to which an alternating current is inputted from an AC power supply, and a pair of output ends which output a direct current. A boost chopper circuit is connected to the pair of output ends, and sets up a DC voltage inputted thereto. The boost chopper circuit functions as a power factor correction circuit. A smoothing capacitor is connected to an output side of the boost chopper circuit, and smoothes the voltage across the smoothing capacitor. An inverter receives the voltage across the smoothing capacitor to apply AC power to a load. A leakage current reduction device outputs a compensating current which compensates for a leakage current leaking from the load. The leakage current reduction device outputs the compensating current, except near the zero crossing of an AC voltage inputted from the AC power supply.

Abstract: Apparatus and methods in accordance with this invention provide a multi-cell power supply for receiving power from a source and delivering power at an output terminal to a load. The multi-cell power supply includes a first power cell coupled to the source, and a first current sensor circuit. The first power cell provides a first output current, and includes a first output terminal coupled to a reference node of the multi-cell power supply, and a second output terminal coupled to the output terminal. The first current sensor circuit includes a first current sensor and a power supply. The first current sensor is coupled to the first output terminal of the first power cell, and measures the first output current. The power supply is coupled to either the reference node or a floating ground node of the first power cell, and provides power to the first current sensor.

Abstract: A method for reducing thermal cycling of a semiconductor power switch includes obtaining a value indicative of a junction temperature of the power switch. The method also includes selecting one of several pre-determined gate drive voltages, based on the obtained value, and providing the selected gate drive voltage to a gate of the power switch. This reduces thermal cycling of a power switch relative to the thermal cycling that would be present during operation at a single gate voltage.

Abstract: A method and an apparatus for determining a phase and a frequency of an electric quantity being associated with an operation of an electrical device are described. The method comprises extracting a fundamental component of the electric quantity, calculating a positive sequence component of the electric quantity based on the extracted fundamental component, and determining the phase and the frequency of the electric quantity based on the calculated positive sequence component.

Abstract: A drive system and method for operating a drive system, including an electromotor, inverter, energy store, the electromotor being able to be supplied from the inverter, which is supplyable from the energy store, a current able to be controlled by a switch being supplyable to at least one stator winding of the electromotor, which is supplied from an electrical energy source that differs from the energy store.

Abstract: A power converting apparatus generates a carrier having a waveform in which an absolute value of a slope is constant with respect to time, based on a value for internally dividing amplitude of the waveform into first and second values. Commutation of a converter is performed when the carrier takes a reference. Adoption is allowed of a zero voltage vector as a switching mode of an inverter in a period in which the carrier takes a first command value to a second command value. A value for internally dividing a value from the reference to a maximum value of the carrier at a ratio between a third value and a fourth value is the first command value. A value for internally dividing a value from a minimum value of the carrier to the reference at a ratio between the third value and the fourth value is the second command value.

Abstract: Systems and methods for performing vector control of grid-connected power electronic converters using a neural network are described herein. Optionally, the grid-connected power electronic converters can be used in renewable and electric power system applications. In order to improve performance and stability under disturbance conditions, integrals of error signals can be introduced as inputs to the neural network. Alternatively or additionally, grid disturbance voltage can be introduced to an output of a trained neural network.

Abstract: A dc link module for a power circuit includes a first connector for connecting to a first power conversion circuit, a second connector for connecting to a second power conversion circuit, wherein the second power conversion circuit is connected to a load circuit arranged to at least intermittently operate as a power source to the power circuit, at least one dc link capacitors arranged between said first connector and said second connector for processing a voltage signal received at said first connector or said second connector, and at least one voltage compensation circuits arranged between said first connector and said second connector, said one or more voltage compensation circuits arranged to generate a voltage signal

Abstract: Universal electrical power conversion methods and systems which may provide the combined capabilities of symmetrical and asymmetrical conversion, bidirectionality, and simplicity are provided. In some cases, the converter charges an inductor connected in parallel between a regulated port and an unregulated port using energy stored by a capacitor positioned in parallel between the inductor and one of the ports until the inductor has a level of current stored that corresponds to the change in voltage desired at the regulated port, then discharges stored energy into the other port until a current cutoff threshold level is reached in the inductor. Creating an LC tank circuit during conversion allows conversion processes to traverse sinusoidal discharge patterns. In some embodiments, the inductor is precharged with current to affect the discharge of the inductor. Multiple ports can be connected and disconnected from the same inductor with these methods and systems.

Abstract: A direct current bus management system can include a power management and distribution unit, having a source management section, a bus management section coupled to the source management section, a load management section coupled to the bus management section, a DC bus coupled to the power management and distribution unit, a plurality of DC sources coupled to the source management section and a plurality of loads coupled to the load management section, wherein the bus management section is configured to reconfigure excess DC power on the DC bus from the DC inputs from the plurality of DC sources based on a plurality of priorities, a plurality of feedback signals and a plurality of system parameters.

Abstract: A renewable energy source is converted into a desired DC voltage that is delivered to a DC motor controller of a permanent magnet motor. A micro controller monitors the amount of supplied renewable DC having the desired DC voltage, which is delivered to each phase of the motor by turning on FET switches on demand. If the renewable DC available at a given instant is not adequate to power a particular phase of the motor, then the micro controller turns on backup FET switches that are part of an independent drive circuit that is in parallel with drive circuits of the renewable DC power circuit, to deliver to the motor line DC, which is produced from an AC supply that has gone through an AC to DC converter. Once charged, the renewable DC power will power the next available phase of the motor.

Abstract: Apparatus and methods in accordance with this invention provide a multi-cell power supply for receiving power from a source and delivering power at an output terminal to a load. The multi-cell power supply includes a first power cell coupled to the source, and a first current sensor circuit. The first power cell provides a first output current, and includes a first output terminal coupled to a reference node of the multi-cell power supply, and a second output terminal coupled to the output terminal. The first current sensor circuit includes a first current sensor and a power supply. The first current sensor is coupled to the first output terminal of the first power cell, and measures the first output current. The power supply is coupled to either the reference node or a floating ground node of the first power cell, and provides power to the first current sensor.

Abstract: A full bridge oscillation resonance high power factor invertor being connected between a power source and a Load has a first inductor and a second inductor. The first and second inductors are respectively connected to a full bridge inverting circuit. The full bridge inverting circuit is connected parallelly to an energy storing capacitor. The present invention integrals conventional multiple stages invertor/convertors as a signal stage which is low cost and provides a very high transforming efficiency. The two inductors share current Loaded of the invertor, the invertor is able to provide a high power transforming performance. Switches of the full bridge inverting circuit all switch under zero voltage to reduce switching loss of the full bridge inverting circuit.

Abstract: A control circuit for controlling one or more power switches of a power converter includes a voltage control loop and a current control loop. The control circuit is configured to generate a current reference for the current control loop using the voltage control loop and an AC reference signal. The control circuit is configured to operate in at least a first mode in which a parameter of the voltage control loop is sampled only at every other zero crossing of the AC reference signal and the sampled parameter is used to generate the current reference for the current control loop. The power converter may be an AC-DC converter or a DC-AC converter (i.e., inverter). Alternatively, the voltage control loop may be sampled at every zero crossing of the AC reference signal, and/or more frequently during transient load conditions.

Abstract: A method and a single-phase voltage type AC/DC converting device and a three-phase voltage type AC/DC converting device arranged between a load and a distribution network. The converting devices are capable of contributing to stabilize a system frequency and a system voltage. By applying an autonomous parallel operation control technique of an AC/DC converter to a load, which receives power from a distribution network, drooping characteristics (governor-free characteristics) for a frequency of active power and voltage-maintaining characteristics (V-Q characteristics) may be obtained. The governor-free characteristics automatically decrease and increase received power when the system frequency decreases and increases, so that even the load may contribute to stabilize the system frequency. The V-Q characteristics generates/absorbs reactive power so as to maintain a voltage at a receiving end constant regardless of load power to further stabilize the system voltage.

Abstract: The invention relates to a method for feeding electrical current into an electrical, three-phase power supply system having a first phase, a second phase and a third phase with a first voltage, a second voltage and a third voltage at a power supply system frequency, comprising the steps of: measuring the first, second and third voltages, transforming the first, second and third voltages into a positive phase-sequence voltage system and a negative phase-sequence voltage system according to the method of symmetrical components, calculating a first desired current, a second desired current and a third desired current for feeding into the first, second and third phases of the power supply system, wherein the first, second and third desired currents are calculated on the basis of at least one value of the positive phase-sequence voltage system and/or the negative phase-sequence voltage system.

Abstract: When an AC voltage is outputted to an inductive load, pulsation of an effective power caused by an odd number-th order harmonic component of a current flowing in this load is reduced. A modulation factor k of an inverter 4 includes a DC component k0 and an AC component. The AC component includes a frequency which is a 6n multiple of the fundamental frequency of AC voltages outputted from the inverter. Even when there are not only the 5th order harmonic component of load currents but also the 7th order harmonic component, it is possible to adequately set the ratio of the magnitude of the AC component and the ratio of the DC component and reduce pulsation of consumption power caused by these harmonic components. Reducing the pulsation contributes to suppression of power harmonics.

Abstract: An AC power supply power circuit comprises a power input unit connected to a DC/AC converter. The AC/DC converter is connected to a DC/DC circuit, and the DC/DC circuit is further connected to an adjustable DC voltage regulation circuit. The adjustable DC voltage regulation circuit is connected to an amplifier to amplify and convert the DC voltages into the AC voltages, thereby outputting different AC voltages and electric currents under the condition of not switching off the power supply and attaining not to stop outputting when adjusting the voltage via cross position, so that a power level is switched promptly and a distortion thereof is very low.