Abstract: A system and method for controlling power flow between power sources and a load in a power system are disclosed. Briefly described, one embodiment is a method for transferring power from a plurality of power sources to an AC system through an IPC module. The IPC module receives a first amount of power from a first power source that is external to the IPC module, receives a second amount of power from a second power source that is external to the IPC module, controls at least a first amount of direct current (DC) power through a first primary converter module coupled to a DC bus, receives a second amount of DC power from a second primary converter module coupled to the DC bus, converts the first and the second amounts of DC power into AC power, and transfers the AC power to the AC power system.

Abstract: A system and method for transferring power from power sources to an AC power system are disclosed. Briefly described, one embodiment electrically couples an external AC power source to a first input power control (IPC) module that is rated at a first AC input power capacity and that is rated at a first direct current (DC ) input power capacity, operates the first IPC module up to the first AC input power capacity in response to receiving AC power from an external AC power source, electrically couples an external DC power source to a second IPC module that is rated at a second AC input power capacity and that is rated at a second DC input power capacity, and operates the second IPC module up to the second DC input power capacity in response to receiving DC power from an external DC power source.

Abstract: A power supply circuit is constructed by a step-up circuit for receiving an input DC voltage to generate a plurality of output DC voltages, and a plurality of voltage regulators, each powered by two voltages selected from a combination of the output DC voltages and the ground voltage. The difference between the two voltages of each of the voltage regulators are substantially the same, to stably operate the voltage regulators.

Abstract: A method and apparatus for aggregating power from multiple sources generates a single direct current regulated voltage. The apparatus comprises a plurality of slave voltage converters and a master pulse width modulator circuit. Providing a plurality of direct current power sources, current is drawn through a plurality of lines connected to the plurality of direct current power sources. An open circuit voltage for each direct current power source is unknown. Each line of the plurality of lines has a line resistance. The line resistance of at least some of the plurality of lines may be unknown. The line resistance of at least some of the plurality of lines is large. The single direct current regulated voltage is generated from the drawn current.

Abstract: A multiple bi-directional input/output power control system includes a network of functional blocks housed in a single enclosure, providing DC power to one or more DC loads, and providing control and internal pathways, sharing one or more AC and/or DC power inputs. The system feeds back AC power from the DC power source into an AC input connection, and the fed-back AC power is shared by other AC loads. The system operates at least one alternative source of DC in a dynamic manner, allowing maximization of power generating capability at respective specific operating conditions of the moment.

Abstract: A combination controller incorporates features of a classic controller and a state space controller to function as a hybrid controller unit. The PID portion of the classic controller regulates the steady state error and is separated from the pulse width modulated constant frequency signal generator that also comprises part of the classic controller. The PID portion is coupled with a state space controller such that the output of the PID controller, i.e., the steady state error correction, is input to the state space controller. The state space controller further receives as input variables a reference sinusoidal signal, the load current, the current across a pre-load filter capacitor, and the output voltage. From these inputs, the state space controller employs principles of differential calculus to generate a transient error correction that is fed to a PWM signal generator for generating a sinusoidal output voltage signal with both steady state and transient error correction.

Abstract: A system for supplying additional power to a module having an internal power supply, the system comprising: a module having an associated power supply, the power supply not being designed to accommodate power sharing; at least one load associated with the module, the load receiving power from the power supply; a variable current limited power source connected to the module supplying additional power to the at least one load; and a controller; whereby the variable current limited power supply is responsive to an output of the controller to vary the current limit of the variable current limited power supply.

Abstract: A power supply method and apparatus of a line interactive UPS utilizes a bi-directional AC/AC power converter in association with the AC delta control concept. When the line voltage coupled to the AC/AC power convert exceeds high/low statuses, the UPS is operated in a line voltage conversion mode, wherein the AC/AC power converter supplies a voltage to compensated the line voltage based on the stability of the line voltage, and then the compensated stable voltage is further provided to the load so as to perform the voltage boost (step-up) and/or voltage buck (step-down).

Abstract: An electrical power control system for use with a recreational vehicle or similar load to selectively control power thereto from either a utility power source or a generator power source comprising a power control stage coupled to the utility power source and the generator power source by a power supply stage to operate the electrical power control system and a utility/generator switch arrangement to selectively direct the power from either the utility power source or the generator power source to the recreational vehicle wherein the power control stage monitors polarity, phase and voltage levels, and controls the utility/generator switch arrangement to selectively feed power from either the utility power source or the generator power source to the recreational vehicle under a predetermined plurality of operating parameters or conditions and fault conditions.

Abstract: A power electronics interface in a microsource controller allows efficient connection in a power system of small, low cost and reliable distributed generators such as microturbines, fuel cells and photovoltaic. Power electronics provide the control and flexibility to insure stable operation for large numbers of distributed generators. The power electronics controls are designed to insure that new generators can be added to the system without modification of existing equipment. A collection of sources and loads can connect to or isolate from the utility grid in a rapid and seamless fashion, each inverter can respond effectively to load changes without requiring data from other sources, and voltage sag and system imbalances can be corrected.

Abstract: A first AC power source comprising a power plant (18), and a second power source, typically grid (10), are normally connected via a high speed isolation switching means (19) to provide sufficient AC power to a critical load (14). The power plant (18) comprises a power generating means, e.g. a fuel cell, (60) and a power conditioning system (PCS) (62) having an inverter (64). Power assurance means (65; 10?, 66, 64, 70; 74, 75) is/are operatively connected to at least one of the first and second power sources to enhance an even and continuous supply of power to the critical load (14). The power assurance means (65; 10?, 66, 64, 70; 74, 75) is/are operatively connected to the PCS inverter (64), and may be one, or a combination of, a surge suppression means (65), a double-conversion power connection means (10?, 66, 64, 70) having a rectifier (66); and/or stored energy means (74), such as a capacitor (75).

Abstract: A switching system, preferably for use in the power supply of motor vehicles, and having one chargeable energy memory of a specific voltage level and consumers situated in the circuit of the energy memory is further developed so that a significant power load is thoroughly prevented even in the case of a high momentary power requirement of the electric consumers. The energy memory is designed for this purpose as power-limiting primary memory (1) to ensure the operation of a first group of consumers (2). The switching system further has a secondary energy memory (4) chargeable proceeding from the primary energy memory (1) which makes energy available to a second group of consumers (5) so that during energy delivery from the secondary energy memory (4) to the consumers (5) of the second group a feedback to the primary energy memory (1) is thoroughly prevented even during loading of the same by consumers (2) of the first group.

Abstract: A hybrid power supply includes a switching type DC/DC boost type converter that receives energy from a primary battery cell and is arranged to deliver the energy to a rechargeable cell, set to provide a fixed output voltage that is less than the full charge voltage of the rechargeable cell. The hybrid power supply includes a circuit including a primary battery current control that senses primary battery current, and controls in part operation of the converter to provide constant current discharge on the primary battery side of the hybrid power supply.

Abstract: An apparatus for anti-islanding protection of a distributed generation with respect to a feeder connected to an electrical grid is disclosed. The apparatus includes a sensor adapted to generate a voltage signal representative of an output voltage and/or a current signal representative of an output current at the distributed generation, and a controller responsive to the signals from the sensor. The controller is productive of a control signal directed to the distributed generation to drive an operating characteristic of the distributed generation out of a nominal range in response to the electrical grid being disconnected from the feeder.

Abstract: A distributed power system, wherein a backup boost transformer is connected between a PFC transformer and a FE DC transformer. The backup boost transformer is also parallel connected with a diode. The backup boost transformer only operates in the sustaining time, if the first DC voltage drops gradually, the backup boost transformer will increase this first DC voltage and stabilize it at a preset voltage of the FE DC transformer. Therefore, the capacity of the storage capacitor of the PFC transformer can be fully utilized to have a longer sustaining time and decrease the variation range of the second DC voltage so as to enhance the efficiency and power density thereof.

Abstract: An electrical system (12) is provided for an automotive vehicle (10) having a first power source (14) with a first positive terminal (16) and first negative terminal (18). A second power source (20) having a second positive terminal (22) and a second negative terminal (24) is also provided. A common electrical node N2 is coupled to the first negative terminal and the second positive terminal. A first load (26) is coupled between the first positive terminal and the second node N2. A second load (30) is coupled to the positive terminal. A switch (SW3) is coupled to the second positive terminal (22), the second negative terminal (24) and the second load (30). The switch (SW3) has a first position electrically coupling the second load to the second positive terminal and a second position electrically coupling the second negative terminal to the second load (30).

Abstract: A hybrid use of a phase-locked-loop controller and a microprocessor-based controller to synchronize the phase angles of a three-phase AC power source, such as a static power converter, with those of a three-phase power grid. The phase-angle synchronization may enable the AC power source to be safely connected to the power grid to provide additional power capacity.

Abstract: A power supply facility includes a primary power circuit coupled to energize a CPU, a control circuit coupled to the CPU, and an auxiliary power circuit coupled to the control circuit for supplying electric power to the CPU via the control circuit. A detecting device nay detect the power supply to the CPU, and may actuate the control circuit to couple the auxiliary power circuit to energize the CPU when the primary power circuit is unable to energize the CPU, or when the electric power supplied to the CPU is cut off, or when the power supply is less then the required value.

Abstract: An electrical system (12) is provided for an automotive vehicle (10) having a first power source (14) with a first positive terminal (16) and first negative terminal (18). A second power source (20) having a second positive terminal (22) and a second negative terminal (24) is also provided. A common electrical node N2 is coupled to the first negative terminal and the second positive terminal. A first load (26) is coupled between the first positive terminal and the second node N2. A second load (28) is coupled between the common node N2 and the second negative terminal (24). A DC-to-DC converter (80) is coupled to the first power source, the second power source and the common node.

Abstract: In an electric power system interconnection device, a primary power supply is connected to a load via a switch and a secondary power supply is connected to a load side of the load via a power converter to establish coordinated interconnection of the primary power supply and the secondary power supply. When the switch is opened in the event of a failure of the primary power supply, the electric power system interconnection device extinguishes an arc current flowing through the switch, at a high speed, by controlling an output current of the power converter using the load current flowing into the load as an output current command for the power converter so that uninterrupted electric power is supplied to the load.

Abstract: The present invention is a battery transfer circuit connected to a load, a power supply for powering the load with at least a minimum supply voltage during normal operating conditions, and a source of battery voltage for powering the load during a power fail condition when the power supply is unable to power said load at the minimum supply voltage. The battery transfer circuit comprises a first circuit for applying at least the minimum supply voltage to the load during normal operating conditions and a second circuit for charging the battery to an optimal voltage greater than the minimum supply voltage and for down-regulating the optimal charge voltage to a predetermined voltage and for applying the predetermined voltage to the load during the power fail condition, wherein the predetermined voltage is less than the minimum supply voltage.

Abstract: A short circuit within the dynamic voltage restorer (1) is immediately detected by a short circuit detection units (9) which permanently monitors currents and voltages in the voltage source converter (3) and energy storage capacitor bank (2). Upon detection a fast discharge of the capacitor bank (2) including firing of all available semiconductors of the voltage source converter (3) and distributing the resulting current stress as evenly as possible within the voltage source converter (3) is initiated. Instead of letting costly fuses interrupt the high short circuit currents, these currents are detected and evenly distributed within the converter.

Abstract: A DC to DC Converter includes an electrical circuit that allows batteries and other electrical energy storage devices to be charged from or to discharge to a variable voltage DC bus. This electrical circuit also enables seamless integration with other energy storage devices and/or DC power sources, such as fuel cells, to provide DC power for a Power Management System. A Power Management System preferably provides both full power source management and power conditioning. The Power Management System is able to manage power flow to and from multiple, isolated power sources and energy storage devices to deliver high quality alternating current (“AC”) power to a load.

Abstract: A power control system for an electric traction motor in a vehicle comprising at least one inverter for providing conditioned electrical power to the electric traction motor, a plurality of power stages for providing DC power to the at least one inverter, each stage including a battery and boost/buck DC—DC converter, the power stages wired in parallel, and where the power stages are controlled to maintain an output voltage to the at least one inverter.

Abstract: A circuit arrangement for supplying electrical energy to a power supply has a fuel cell and an accumulator arrangement. Electrical energy is delivered by the accumulator arrangement during the starting procedure, and is fed into the power supply by the accumulator arrangement via at least one DC/DC converter during starting of the circuit arrangement.

Abstract: In an electric power system interconnection device, a primary power supply is connected to a load via a switch and a secondary power supply is connected to a load side of the load via a power converter to establish coordinated interconnection of the primary power supply and the secondary power supply. When the switch is opened in the event of a failure of the primary power supply, the electric power system interconnection device extinguishes an arc current flowing through the switch at a high speed by controlling an output current of the power converter using the value of a load current flowing into the load as an output current command for the power converter so that uninterrupted electric power is supplied to the load.

Abstract: To solve a problem due to a transient regulation phenomenon (6) at the time of an increase in power demand (1) in a mobile telephone, the regulator is pre-compensated (7) at a time (T′) in advance of a predicted time (T) of the increase in electrical power demand in the mobile telephone. As a result, a power supply voltage (Vr) crossing an operating threshold (3) outside a period of use has no harmful effect on the operation of the mobile appliance.

Abstract: A power system (8) is provided for economically supplying uninterrupted electrical power to one or more critical loads (14). One or more fuel cell power plants (18) provide one substantially continuous source of power, and a utility grid (10) provides another source of power. The fuel cell power plants (18) are adapted to be, and are, normally substantially continuously connected and providing power to, the critical load(s) (14). A rapidly-acting static switch (19) selectively connects and disconnects the grid power supply (10) to the critical load(s) (14) and with the fuel cell power plant(s) (18). A switch controller (49, 45) controls the state of the static switch (19) to connect the grid power source (10) with the critical load(s) (14) and the fuel cell power plant(s) (18) during normal operation of the grid (10), and to rapidly (less than 4 ms) disconnect the grid power source (10) from the load(s) (14) and fuel cell power plant(s) (18) when operation of the grid (10) deviates from normal beyond a limit.

Abstract: The invention in the simplest form is a method and apparatus for reliably protecting against island situations with one or multiple power sources connected to an electric distribution grid. The method and apparatus detects variations in the voltage and frequency of the grid. An observed change in grid voltage causes a change in output power that is sufficient to cause an even larger change in grid voltage when the utility AC power source is disconnected. An observed change in grid frequency causes a change in phase or reactive output power that is sufficient to cause an even larger change in grid frequency. If several shifts in voltage or frequency happen in the same direction, the response to the change is increased in an accelerating manner.

Abstract: Process and circuit layout for using an independent capacitor for the momentary retention of an output voltage when an input voltage is lost. To facilitate a reduction in capacitance in independent circuits of this type at a constant amount of charge, the input voltage is transformed by a DC/DC up converter to a higher capacitor voltage, which is stored in the independent capacitor and the capacitor voltage is transformed by a DC/DC down converter to the output voltage for the load element, which is less than the capacitor voltage. As the DC/DC down converter can utilize capacitor voltages until the output voltage is reached, the residual voltage remaining in the independent capacitor (C) is no longer used. The independent time interval is correspondingly short. According to the invention, the capacitor is disconnected from the output of the DC/DC up-converter and connected to its input when the input voltage is less than a reference voltage.

Abstract: A disk drive is connectable to a power supply having a fixed DC voltage. The disk drive includes a voice coil motor (VCM) and a spindle motor having a plurality of windings and a rotor rotatable at a variable spin-rate. A spindle motor driver is coupled to the fixed DC voltage and at least one of the windings for controlling the spin-rate of the rotor. The rotor has permanent magnets that induce an AC voltage across the windings while the rotor is rotating. A rectifier circuit rectifies the AC voltage across at least one of the windings to produce a rectified DC voltage. A first switch provides the rectified DC voltage to a first node. A second switch provides the fixed DC voltage to the first node. The first node has a first node DC voltage that is determined by the rectified DC voltage provided by the first switch and the fixed DC voltage provided by the second switch. The first node DC voltage is greater than the fixed DC voltage during a track seeking operation in the disk drive.

Abstract: A 2N redundant power system and method is disclosed that uses cross-coupled AC power transfer. Two cross-coupled AC Transfer switches always connect power converting hardware to an active AC source so that the 2N redundant power system prevents changes in the operating conditions when the loss of one AC source occurs. The system includes a first power source for providing power to a load through a first branch, a second power source for providing power to the load through a second branch and a pair of AC transfer switches cross-coupling the first power source to the second branch when a failure to the second power source is detected, and vice versa. A first and second contactor arrangement each include a first contactor and a second contactor connected in series. A control circuit includes a first coil system for controlling the first contactor arrangement, a second coil system for controlling the second contactor arrangement, and a coil system selection circuit.

Abstract: An energy storage and distribution system provides energy from a first energy related infrastructure characterized by a first energy grid to a second energy related infrastructure characterized by a second energy grid that is substantially independent of the first energy grid. The system includes an energy storage facility that is located in substantial proximity to a common boundary of the first and second energy related infrastructures, and a first energy transport mechanism that is coupled to the first energy related infrastructure and is capable of providing energy for storage in the energy storage facility. The system also includes a second energy transport mechanism that is coupled to the energy storage facility and is capable of providing energy from the energy storage facility to the second energy related infrastructure. Each of the first and second energy grids has an electrical power generation unit and high voltage A/C transmission lines.

Abstract: In order to provide an inverter apparatus and a solar power generation apparatus in which when a main AC power system (5) has suffered, e.g., a power failure, the operation mode of an inverter (2) in the tie operation with the main AC power system (5) can be easily and safely switched from the tie operation mode to the self-support operation mode, and electric power can be supplied to a load (4) directly using normal indoor wiring, the open/closed state of a switch (3) for opening/closing a connection between the output terminal of the inverter (2) and the main AC power system (5) is detected, and the self-support operation of the inverter (2) is started when the open state of the switch (3) is detected.

Abstract: Power is supplied to a load from either a first power source or a second power source. A transfer switch determines which of the power sources provides the power to the load. A switch control detects a loss in the power provided by a first power source and signals the transfer switch to switch to a second power source. A small energy storage device provides power to the load, during the switch from the first power source to the second power source.

Abstract: A method and circuit arrangement for covering peak energy demand in an electrical AC or three-phase current network having a plurality of consumers of which at least some of the consumers are equipped with a stand-by power supply network having accumulators and at least one rectifier fed from the electrical network. The method includes feeding a fraction of energy from the accumulators of each individual stand-by power supply network into the electrical network via inverters for a short term peak demand of the electrical network. The fraction of energy is fed from the accumulators as long as peak demand is present and sufficient energy for the stand-by power supply is still available in the accumulators.

Abstract: An uninterruptible power supply which is advantageous for use with a computer receives power alternatively from a utility main power source or a rechargeable battery. The uninterruptible power supply includes an input for receiving AC utility power, an AC to DC converter coupled to the input, receiving AC power from the input, having at least one regulated D.C. output, and generating DC power at an output of the converter, a transformer having a primary winding and a secondary winding, an inverter coupled between the AC to DC converter and the primary winding of the transformer and arranged to supply a chopped DC voltage to the primary winding to cause a corresponding chopped DC voltage having an amplitude V.sub.s to be generated across a secondary winding of the transformer coupled to the output, an auxiliary power supply having an energy store having a supply terminal that is operable at a voltage V.sub.

Abstract: A polarity reversing circuit having energy compensation may comprise a first inductor connected between the first electrode and a negative terminal of a power supply. The positive terminal of the power supply is connected to the second electrode. A diode and a first capacitor are connected in series across the first inductor so that the cathode of the diode is connected to the first electrode. A second capacitor and a switching device are also connected in series across the first and second electrodes. A second inductor is connected between the switching device and the anode of the diode. A bi-directional converter is connected between the power supply and the second capacitor. The voltage polarity between the first and second electrodes may be reversed by actuating the switching device to switch between a non-conducting state and a conducting state.

Abstract: In a computer apparatus including an enclosure and a direct access storage device mounted within the enclosure, a mounting apparatus for the direct access storage device including: a plurality of a relatively rigid shock isolators and at least one stress sensor mounted in series with are of said shock isolators and disposed between the enclosure and the direct access storage device. The enclosure may include a user frame and the mounting apparatus may be disposed between the direct access storage device and the frame. There may be one stress sensor for each of the shock isolators. The shock isolators may be coupled to the direct access storage device. Each stress sensor may include a piezoelectric element. Preferably the shock isolators are rigid enough so that the resonant frequency of said mounting apparatus is at least 800 Hz, but can be 800 Hz or higher.

Abstract: A superconducting magnetic energy storage system for applying power to a load includes a superconducting magnet, the inductor of which is supplied with current via a source which may be preset to a desired value of current, and wherein a feedback loop responsive to a sensed current adjusts the source to provide the desired current. Energy from the superconducting magnet is transferred via a series of pulses of current from the magnet to a first capacitor for charging the capacitor to a desired voltage greater than the voltage at the superconducting magnet. A further transfer of energy, via a series of pulses of current, results in a charging of a second capacitor to a voltage lower than the voltage of the first capacitor. The second capacitor feeds the load.

Abstract: In a backup power system capable of deriving power from alternate AC primary and DC backup power sources to provide continuous AC power to an AC load and including an inverter/switch module having DC and AC inputs and an AC output, a maintenance bypass switch for, and method of decoupling the AC primary and DC backup power sources from the backup power module to allow maintenance to be performed thereon.

Abstract: A power generation technique to generate power for use in, for instance, a communication device having a transmitter and a receiver, where communication occurs over atmosphere, or airways (e.g., wireless). The present invention provides a battery-based system that generates power at a high current and high voltage while accommodating the required duty cycles using batteries with sizes that are not prohibitive given the size constraints associated with portable devices in general.

Abstract: A booster type DC-DC conversion circuit and a voltage reduction type DC-DC conversion circuit are connected in series with a battery. When battery voltage is high, the booster type DC-DC conversion circuit does not operate, and the voltage reduction type DC-DC conversion circuit outputs a constant voltage lower than the battery voltage. When the battery voltage drops, the booster type DC-DC conversion circuit operates, and converts the battery voltage to a constant voltage higher than the operation voltage of the voltage reduction type DC-DC conversion circuit. The voltage reduction type DC-DC conversion circuit outputs a constant voltage. The power supply apparatus can continuously output a constant voltage from when the battery voltage is high until it becomes low, and can efficiently utilize the battery capacity.

Abstract: This electric power supply system includes an air conditioner serving as load, a solar photovoltaic cell for supplying power to the air conditioner, and a system power control circuit and further including a commercial power source for use in combination with the solar photovoltaic cell for supplying additional power when insufficient, power is supplied from the solar photovoltaic cell to the air conditioner. In an operation state of the air conditioner, the system power control circuit operates to regulate an operating point of the solar photovoltaic cell and variably regulate the supplied power from the solar photovoltaic cell while comparing required power of the air conditioner with the supplied power from the solar photovoltaic cell.

Abstract: The power supply system for a DC powered electrical transit system is adapted to accommodate normal, surge and continuous peak demands by locating battery equipped secondary power supplies at locations which create excess power demands such as at passenger stations, at the beginning of an uphill grade and at midpoints between the primary power supplies. During normal operation, the batteries are charged and during surge or peak demand periods, are discharged to provide additional power to the system.

Abstract: An ac electric drive system includes a bidirectional power semiconductor interface between a battery, or an auxiliary energy storage device, and a power inverter for boosting an input dc voltage and for decoupling the dc link voltage from the input dc voltage such that the dc link voltage is substantially independent of the input dc voltage and the parameters of the battery or energy storage device. The input dc voltage is controlled to maximize efficiency along predetermined torque envelopes.

Abstract: An inverter control device that controls a self-commulated inverter connected to an AC power system via a three phase transformer and in so doing suppresses DC magnetization in the three-phase transformer. The device includes a current DC component detecting circuit for detecting the current DC components contained in at least two of the three phase output AC currents of the inverter and a DC magnetization suppressor signal generating circuit for producing two correcting signals from the current DC components. The two correcting signals are used to balance in amount the three voltage DC components contained in the three phase output AC voltage of the inverter, respectively. An output reference correcting circuit is provided to correct two of first output references in accordance with the two correcting signals and output three second references including the two corrected values and one of the first output reference.

Abstract: Power supply apparatus is disclosed which can be configured as a power line filter or an uninterruptible power supply having a battery test on load capability. It comprises an input reversible rectifier connectable between an AC supply and a high voltage internal DC bus, a second reversible rectifier interconnecting storage batteries to the high voltage DC bus, and an output module supplying a desired DC output or an AC output. In use the voltage on the internal DC bus is maintained at a greater level than that of (a) the instantaneous repetitive peak of the incoming voltage, and (b) the peak battery storage voltage. Battery test means is provided by allowing the dumping of the charge stored within the storage batteries for a certain period at the maximum available rate into the internal bus and back into the AC supply through the said reversible rectifiers; meanwhile observing the extent of the battery voatage drop so caused.

Abstract: A universal phase-controlled reversible power converter having one transformer with multiple windings (i) couples a fixed d.c. voltage to an associated transformer winding through a fixed port having switches controlled for switching by fixed-phase signals, and (ii) couples any number of voltages having any waveform(s) whatsoever each to an associated transformer winding each through an associated variable port that has a filter with an inductor and controllable switches. Variable-phase switching control signals control the variable ports to produce any desired three-state demodulated waveform. A three-state demodulated waveform is filtered to present (i) a corresponding counter emf of any desired waveform to an input source or power, or (ii) any desired output waveform to a sink of power. Controllably producing the counter emf as a picture-of-the-line-input-voltage makes the load factor of the power converter, and all its loads, unity.

Abstract: A power system (8) is provided for economically supplying uninterrupted electrical power to one or more critical loads (14). One or more fuel cell power plants (18) provide one substantially continuous source of power, and a utility grid (10) provides another source of power. The fuel cell power plants (18) are adapted to be, and are, normally substantially continuously connected and providing power to, the critical load(s) (14). A rapidly-acting static switch (19) selectively connects and disconnects and reconnects the grid power supply (10) to the critical load(s) (14) and with the fuel cell power plant(s) (18) for abnormal and normal grid operation, respectively. A switch controller (49, 45) controls the state of the static switch (19) to connect the grid power source (10) with the critical load(s) (14) and the rapidly (less than 4 ms) make the disconnections and the reconnections.