Abstract: The present disclosure provides a method for controlling an energy control system. The method includes detecting a power outage at a grid interconnection. The method includes connecting a first set of the plurality of backup loads to a backup load interconnection, in which the backup load interconnection is electrically coupled to a backup power interconnection. The method includes disconnecting a second set of the plurality of backup loads from the backup load connection such that power is interrupted between the backup power source and the second set of backup loads. The method includes receiving a request from a user device to connect at least one load of the second set of the plurality of backup loads to the backup interconnection. The method includes determining whether to connect one load of the second set of the plurality of backup loads to the backup interconnection according to one or more programmed rules.

Abstract: This uninterruptible power supply device includes an input module provided with a plurality of conductor wires having a plate shape including at least a plurality of AC input wires, and an uninterruptible power supply module. In addition, the plurality of AC input wires each extend in an X direction in which the uninterruptible power supply module and the input module are adjacent to each other, and have AC input cable attachment portions in which an AC input cable is attached. The AC input cable attachment portions are disposed so as to be separated from each other in a Y direction, which is a direction in which a front side and a rear side of the input module face each other.

Abstract: A backup power supply system and a control method thereof are provided. The backup power supply system includes a power supply circuit and an uninterruptible power supply. The power supply circuit is configured to receive utility power, and the uninterruptible power supply is connected to the power supply circuit and stores backup power. When the utility power is normal, the power supply circuit supplies power to the uninterruptible power supply, and the uninterruptible power supply outputs a first alternating current voltage that meets a utility power specification to the alternating current load. When the utility power is abnormal, the uninterruptible power supply outputs a second alternating current voltage that meets the utility power specification to the alternating current load.

Abstract: A modular edge power system is provided. The modular edge power system includes a housing and multiple edge modules. Each edge module is adapted to be removably inserted into the housing and provide, through a corresponding bus and with one or more power equipment submodules, power to one or more compute devices in a rack. Each bus is adapted to provide sufficient power to enable operation of every compute device in the rack.

Abstract: The application discloses an automatic transfer switch and a power supply system. The automatic transfer switch includes: a first switch unit having a first end connected to a first device through a converter port, and a second end electrically connected to a power grid through a power grid port; a second switch unit having a first end connected to a second device through an electric vehicle port and a charging/discharging circuit unit, and a second end electrically connected to the second end of the first switch unit; a third switch unit, having a first end electrically connected to the power grid through the power grid port, and a second end electrically connected to a load through a load port; a sampling unit; and a control unit connected to the sampling unit.

Abstract: This application provides a power supply method for a data center. The data center includes a first device and at least one second device, an importance of a first service in the first device is higher than an importance of a second service in the at least one second device, and the second service in the at least one second device is transferable. A power supply apparatus includes a first uninterruptible power supply UPS and a second UPS, the first UPS is configured to control a first power source and a first energy storage apparatus to supply power to the first device, and the second UPS is configured to control the first power source and a second energy storage apparatus to supply power to the at least one second device.

Abstract: An electrical system can include a first bidirectional AC-DC converter having an input couplable to a grid connection and an output couplable to a battery and a second bidirectional AC-DC converter having an input couplable to the grid connection or a convenience outlet and an output couplable to the battery. The electrical system can further include a controller that controls the first and second converters to operate in a plurality of modes including a two-stage charging mode in which the first and second converters operate in a forward direction to charge the battery, a single-stage charging mode in which the first converter operates in a forward direction to charge the battery and the second converter operates in a reverse direction to power the convenience outlet, and a non-charging mode in which the first converter is idle and the second converter operates in a reverse direction to power the convenience outlet.

Abstract: A method for operation of UPS modules connected in parallel is provided. The method includes: in a case that a UPS system is constructed based on multiple UPS modules connected in parallel, sleeping, based on a system load rate, a predetermined number of UPS modules to control the UPS system to operate at a predetermined efficiency level; controlling UPS modules not being slept in the UPS system to enter into a main-inverter power supply mode or a main-bypass common mode to perform reactive power and harmonic compensation; and waking up the slept UPS modules when the system load rate drops by a predetermined value due to a sudden addition of a load. The UPS modules can be slept or waked up intelligently based on the system load rate in the dynamic online mode, ensuring that the UPS system operates around highest efficiency.

Abstract: A three-phase uninterruptible power system and an operation method thereof are provided. The three-phase uninterruptible power system comprises a DC bus, three power conversion circuits and a control circuit. When the three-phase uninterruptible power system enters a line mode from a battery mode, the control circuit performs a huge current suppression for each power conversion circuit according to a predetermined sequence. The huge current suppression performed for any of the power conversion circuits comprises the following steps: disabling the DC-DC conversion of the power conversion circuit, and having the other two power conversion circuits to additionally share the original load of the disabled power conversion circuit; and after the DC-DC conversion of the power conversion circuit is disabled, enabling the AC-DC conversion of the power conversion circuit, and having the power conversion circuits revert to their original load.

Abstract: A semiconductor power module including first and second power transistors situated in parallel between first collector and first emitter strip conductors. A first connection surface of each of the power transistors is electroconductively connected to the first collector strip conductor, and a second connection surface of each of the power transistors is electroconductively connected to the first emitter strip conductor, so that a current flowing between the first collector strip conductor and the first emitter strip conductor is divided between the power transistors when the power transistors are each conductively connected via an applied control voltage. A first external power contact is directly contacted with the first collector strip conductor at a first contact area, a second external power contact is contacted with the first emitter strip conductor at a second contact area via a first connecting element, and the second contact area is positioned asymmetrically between the power transistors.

Abstract: Embodiments of this application provide a power conversion circuit. The power conversion circuit includes at least one first power conversion unit connected in series to a first phase line, at least one second power conversion unit connected in series to a second phase line, at least one third power conversion unit connected in series to a third phase line, a plurality of first start circuits connected in series to the first phase line, and a plurality of second start circuits connected in series to the second phase line. Each first start circuit includes a first relay and a first resistor that are connected in parallel, and first relays in all the first start circuits are sequentially closed after the power conversion circuit is powered on, to start the power conversion circuit. Each second start circuit includes a second relay and a second resistor that are connected in parallel.

Abstract: This DC/DC conversion system is provided between a plurality of DC power supplies and a common DC bus, and includes, for each of the plurality of DC power supplies: a DC/DC converter provided between the DC power supply and the DC bus; and a control unit configured to control the DC/DC converter. The control unit corrects a voltage detection value for the DC bus by taking in an individual voltage detection deviation for the DC bus compared to an entirety of a plurality of the DC/DC converters present in parallel, and controls the corresponding DC/DC converter in accordance with a voltage command value having droop characteristics with respect to output power. The DC/DC conversion system as described above can uniform outputs while operating the plurality of DC/DC converters in parallel without the need of fast communication.

Abstract: An intelligent switch device and a power generation system are provided. The intelligent switch device includes a first power port, a second power port, a switch unit and a control unit. A first end of a switch unit is connected to a first power supply via a first power port, and a second end of the switch unit is connected to a second power supply via a second power port. The control unit is configured to control the switch unit to be turned on for a first time period when the first power supply is in abnormal condition, where the abnormal condition causes the switch unit to be tripped. The first time period is greater than or equal to a time period required for a device to respond to the abnormal condition.

Abstract: A method for controlling an uninterruptable power supply arranged between a grid and a variable load, the uninterruptable power supply includes a DC link interconnecting a rectifier connected to the grid via a grid switch, an energy storage and an inverter connected to the load, and a switchable bypass connected between the grid switch and the load and in parallel with the path formed by the rectifier, the DC link and the inverter, the method includes monitoring a power supply of the grid, comparing the power supply to a load requirement of the load, if the power supply meets the load requirement, closing the grid switch, and switching on the bypass, to supply the load with AC current from the grid.

Abstract: A method performed by a first node includes determining a routing metric for individual nodes in a set of nodes, receiving a network packet from a second node, selecting a third node in the set of nodes based on the routing metrics, and transmitting the network packet to the third node. The routing metric for a respective one of the set of nodes being based on at least one of a power storage status of the respective one of the set of nodes or a solar power generation status of the respective one of the set of nodes.

Abstract: The present specification relates to a power supply system which enables uninterruptible power supply, wherein a circuit breaker is provided to switch on/off each of electric circuits via which a plurality of power supply devices are connected, and thus the UPS function can be performed among the plurality of power supply devices by opening or closing the circuit breaker according to various situations occurring in the system to control power reception and supply.

Abstract: A battery stack includes a plurality of battery management system (BMS) nodes and a controller. Each BMS node includes a battery, an isolation switch configured to selectably isolate the battery of the BMS node from the batteries of the other BMS nodes, and a bypass switch configured to selectably provide a path for electrical current flowing through the battery stack to bypass the battery of the BMS node. The batteries of the BMS nodes are electrically coupled in series. The controller is configured to control the isolation switch and the bypass switch of each BMS node such that the battery of each BMS node can be individually connected to and disconnected from an electrical power source/sink.

Abstract: In switching of a microgrid from an isolated operation to an interconnected operation with a power grid, a CEMS server determines a first master DER and slaves based on a master plan and performs master-slave control. When the first master DER goes down, the CEMS server compares remaining capacities of power-storage-type DERs included in a DER group. The CEMS server then determines a DER with the highest remaining capacity as a second master DER among the power-storage-type DERs included in the DER group and performs master-slave control.

Abstract: A battery module is disclosed having a plurality of battery cells and internal relay controllably coupled to an internal module controller, said controller having a plurality of programmed states. Transitions between programmed states are disclosed responsive to a secure command message, and responsive to a monitored operating condition. Passive and active states are disclosed. A modular battery pack is disclosed consisting of a plurality of modules connected in parallel, which can be individually and independently activated and deactivated responsive to a secure command message. Methods are provided for authentication of command messages and for authentication of the command message source.

Abstract: Energy allocation system comprises a solar panel system and a local energy storage system, each capable of being plugged into a power socket of a home grid and each having a communication unit. The system further comprises a control unit, comprising a third communication unit, configured to receive the information relating to the solar panel system, and the information relating to the energy storage system via said communication units, and a processing unit. The processing unit is configured to determine, based on the received information, an allocation of energy in the home grid to the energy storage system, and to accordingly generate a control signal for the energy storage system. The third communication unit is further configured to transmit the generated control signal to the energy storage system.

Abstract: A DC switch with embedded de-multiplexing function links a plurality of DC switches in a priority chain and enables concurrent power switching between DC switches. The priority chain automatically selects a most cost-effective power for output to optimize energy utilization efficiency and with a just-in-time enable to activate standby-power to minimize energy waste in persistent DC power.

Abstract: Disclosed is an electrical unit with a first port configured to be operatively connected to an AC-grid, a second port configured to be operatively connected to an AC-load, and a third port to be operatively connected to an AC-side of a first inverter. The electrical unit includes a first choke arranged between the third port and the second port. The electrical unit is configured to transfer electrical power provided by the first inverter from the third port via the first choke to the second port. The electrical unit is configured to provide grid-forming electrical power to the second port in case of disconnection from the AC-grid at the first port. Further disclosed is a backup power system and a method for operating a backup power system.

Abstract: This invention is directed to systems and methods that track a specified stored energy level profile for a BESS in a microgrid. The systems and methods including using a control algorithm that tracks the stored energy level profile for the BESS. The controller algorithm includes a Kalman Filter design for a model-based state reconstruction to overcome sensor/communication errors during real-time operation. The latter is important to guarantee the ability of the microgrid to continue its seamless operation during periods of erroneous sensor measurements or flawed communication.

Abstract: Vehicles can employ onboard telematic monitoring devices to collect vehicle and operation data, such as for improved vehicle fleet management. Such telematic monitoring devices are dependent on power from a vehicle, such that data collection and communication can be interrupted if a telematic monitoring device is disconnected or has a poor connection. The present disclosure relates to battery devices, which provide power to telematic devices as needed in order to maintain data collection and communication, or other more limited functionality. The present disclosure also relates to systems including battery devices, and methods for operating battery devices.

Abstract: A power supply for an energy management and monitoring unit includes a line arrangement with multiple lines representing inputs or outputs, each of which has at least one power line for supplying power. A merging unit combines the power lines of the line arrangement to a total voltage, and a splitting unit is configured to split the total voltage into at least two redundant voltages provided for the energy management and monitoring unit.

Abstract: An uninterruptible power supply (UPS) system operable in an energy saver mode includes: a static bypass switch connected between an input connector and an output connector of the UPS system and being activatable to operate the UPS system in the energy saver mode; a plurality power modules, each of the plurality of power modules being connected between the input connector and the output connector of the UPS system and at least some of the plurality of power modules being controllable for a reactive power compensation; and a controller for controlling one or more of the controllable power modules depending on a data input related to a reactive power compensation. The controller controls one or more of the controllable power modules depending on the data input such that a reactive power flow via the UPS system is adjusted.

Abstract: According to certain aspects of the disclosure, an uninterruptible power supply is provided comprising an input, a backup power supply, an output configured to provide output power from the input and/or the backup power supply, a sensor, a relay, and a controller coupled to the sensor and the relay and being configured to determine, based on stored relay specifications, a manufacturer total estimated relay lifetime, receive operational information indicative of operational parameters of operation of the relay from the sensor, the operational information including a current conducted by the relay, determine, based on the operational information, an effective number of relay cycles consumed by the operation of the relay, determine a modified number of remaining relay cycles based on a difference between the manufacturer total estimated lifetime and the effective number of relay cycles consumed, and output remaining relay lifetime information indicative of the modified number of remaining relay cycles.

Abstract: A standalone direct current (DC) power supplying system, which is not connected to commercial power, includes a power conditioner that supplies generated power W2 of a power generator to a DC bus, DC/DC converters that convert a bus voltage Vbs and supply load power (WLa+WLb) to load appliances, bidirectional DC/DC converters that supply a constant DC current from the DC bus to storage batteries or from the storage batteries to the DC bus, and an energy management system. When the generated power W2 exceeds the load power (WLa+WLb), the energy management system causes the converters to supply a constant DC current with a common charging rate to the storage batteries, and when the generated power W2 falls below the load power (WLa+WLb), the energy management system causes the converters to supply a constant DC current with a common discharging rate from the storage batteries to the DC bus.

Abstract: An electric energy transmission system which does not need a reservation has a generator generating a multi-phase electric current, a converter converting it into another electric current, an electric current network connected with the converter and having a first group of electric current lines extending towards electric current users and a second group of electric current ones electrically connecting the electric current lines of the first group with each other, and a plurality of consumer blocks connected with the network and having users which use different electric currents and further converters converting the electric current transmitted by the network into the different electric currents and supplying the different electric currents to the electric current users.

Abstract: A power supply apparatus includes a control circuit, and first and second power storage connected to a DC link circuit between an inverter and a converter. The control circuit, while the AC power supply is in a normal condition, controls the first power storage to discharge when the control circuit detects that electric power consumption exceeds a threshold, and controls at least one of the first and second power storage to charge when the control circuit detects that the electric power consumption does not exceed the threshold, and while the AC power supply is in an abnormal condition, controls the second power storage to discharge, and controls the first power to discharge when it is detected that the electric power consumption exceeds the threshold.

Abstract: Hybrid welding systems and portable hybrid welding modules are disclosed. An example portable welding power supply includes an output converter circuit to convert direct current (DC) power to welding power, the DC power comprising at least one of DC input power or converted battery power. The portable welding power supply also includes a battery and a bidirectional DC-DC converter circuit configured to receive the DC input power and coupled to the battery. The portable welding power supply also includes a control circuit configured to control the output converter to output the welding power, control the bidirectional DC-DC converter circuit to convert the DC input power to charge the battery, and control the bidirectional DC-DC converter circuit to convert power from the battery to provide the battery power to the output converter.

Abstract: In a power conditioner, a DC-DC converter outputs an output of a first power source for which reverse power flow is permitted to a DC supply line, and a bidirectional DC-DC converter discharges an output of a second power source for which reverse power flow is not permitted to the DC supply line and, on the other hand, charges power of the DC supply line to the second power source. A DC-AC inverter converts DC power of the DC supply line to AC power and outputs the converted power to outside. When a power consumption of a load exceeds a rated output of the DC-AC inverter and a power generation amount of the first power source exceeds the rated output of the DC-AC inverter, a portion of surplus power of the first power source is charged to the second power source.

Abstract: A control method for a power supply system includes a driving circuit conducting a switch element of a first backup transforming module of a backup supplying module corresponding to a phase of one of a plurality of power transforming modules in an abnormal operation according to a working signal corresponding to the power transforming module in the abnormal operation, when one of the plurality of power transforming modules corresponding to a three-phase voltage source is in the abnormal operation; and the driving circuit latching unconducted switch elements of at least one of undriven second backup transforming module of the backup supplying module corresponding to the phase, after a logic control circuit detects working signals corresponding to all phases of each backup transforming module, and latching unconducted switch elements corresponding to phases different with the phase of the first backup transforming module.

Abstract: Systems, methods, and apparatuses are provided herein for implementing a PoE system comprising a plurality of power sourcing equipment that power a single powered device. Control circuitry may determine the power necessary to operate a powered device in a first power mode, and may cause the powered device to draw, from a first power sourcing device, to a first port of the powered device, a first wattage. The powered device may draw, from a second power sourcing device, to a second port of a powered device, a second wattage, where a sum of the first and second wattage equals the amount of power necessary to operate in the first power mode, wherein a first isolation boundary isolates the first power sourcing equipment, the first Ethernet link, and the first port, and wherein a second isolation boundary isolates the second power sourcing equipment, the second Ethernet link, and the second port.

Abstract: A method for a network apparatus to control power provision to a powered device is proposed. The network apparatus is configured for connection to the powered device, an electronic device, and a power supply device. The network apparatus permits transmission of electronic power provided by the power supply device to the powered device therethrough when the electronic device is communicatively connected to the network apparatus, and does not permit transmission of electronic power provided by the power supply device to the powered device therethrough when the electronic device is not communicatively connected to the network apparatus.

Abstract: A system is disclosed which eliminates problems caused by surges of electric energy which is generated on a utility customer's property and which is fed back onto a utility-owned service line by maintaining a minimum utility provided percentage (MUPP) of power being provided onto a customer-owned dead-end service line. Where the electric energy generated by a utility customer is incrementally excluded from the customer-owned dead-end service line through a plurality of contactors which are controlled by a 120 volt command line.

Abstract: Power systems include a housing and an automatic transfer switch (ATS switch) held in the housing, a Bypass switch held in the housing and a control circuit in communication with the ATS switch and the Bypass switch to automatically direct the Bypass switch and the ATS switch to carry out the selective connections to thereby allow automated, redundant power transitions to the system load from three different power sources.

Abstract: A device for supplying electrical power including one or more photovoltaic panels. An example device includes a primary battery electrically coupled to the photovoltaic panels. An electric motor is electrically coupled to either or both of the primary battery and the photovoltaic panels. A generator is mechanically coupled to the electric motor. A positive bus bar and negative bus bar are electrically coupled to the generator. At least one secondary battery is electrically coupled to the bus bars. At least one electrical outlet electrically coupled to the positive bus bar and negative bus bar. Electrical energy is stored in the at least one secondary battery when the supply from the generator exceeds the demand on the at least one electrical outlet. Electrical energy is discharged from the at least one secondary battery when the demand from the at least one electrical outlet exceeds the supply from the generator.

Abstract: Systems and methods relating to power inverters for power generation systems. A power inverter suitable for renewable power sources is configured with a data processing module that receives power related data from a power grid and from a battery backup inverter. The data processing module calculates mode of operation data based on the power related data and, if the mode of operation data exceeds a threshold, then the power generation system is operating in an off-grid mode (i.e. the system is decoupled from the power grid). If the mode of operation data is equal or less than the threshold, then the power generation system is operating in an on-grid operating mode. The system is also self-tuning with respect to the threshold value.

Abstract: Systems for providing power are provided including an uninterruptible power supply (UPS) coupled to a first power source, the UPS including at least one battery therein; and at least one external battery module (EBM) coupled to the UPS and a second power source, the second power source being different and separate from the first power source. Each of the at least one EBMs include a communication circuit configured to communicate with the UPS and/or other EBMs; at least one battery string; and a battery charger coupled to the at least one battery string and the at least one battery in the UPS, the battery charger being configured to charge the at least one battery string and the at least one battery in the UPS responsive to a communication from the EBM through the smart card when power from the second power source is removed. Related EBMs and UPSs are also provided.

Abstract: A power control apparatus has a switch configured to interrupt power supply from a system power when the switch has detected a drop of voltage from the system power below a threshold, a first power controller configured to receive a voltage drop signal supplied from the switch unit, a first power storage unit connected to the first power controller, a second power controller configured to receive a discharge start signal supplied from the first power controller, a second power storage unit connected to the second power controller, and a rotary machine generator that receives an operation control signal supplied from the second power controller or the second power storage unit.

Abstract: Systems and methods for measuring and modifying an input voltage provided to a control panel are provided. Some systems can include measuring the input voltage provided by a power supply, determining whether the input voltage is within a range of acceptable input voltages, transmitting, to the power supply, a modulated signal on a direct current line between the power supply and the control panel instructing the power supply to modify the input voltage, and generating a notification when the input voltage is outside of the range of acceptable input voltages.

Abstract: A power generation system includes a plurality of power generation apparatuses. The power generation system is configured to supply electric power to a load by performing interconnecting operation of the plurality of power generation apparatuses sets one of the plurality of apparatuses as a master apparatus and the other power generation apparatus as a slave apparatus. When power consumption by the load is less than electric power, the master apparatus causes the master apparatus and the slave apparatus to generate power in such a manner that the electric power supplied to the load follows the power consumption by the load. The electric power is generated by rated operation of the master apparatus and the slave apparatus.

Abstract: Provided is a plurality of modules containing a computer that has a network interface to which power is supplied with PoE. The plurality of modules is connected to a network. A first module that receives a response indicating that requested power is not able to be supplied from the network performs a process of displaying an abnormality. The first module notifies a second module of the abnormality via the network. The second module controls display of the abnormality when the second module is notified of the abnormality.

Abstract: A power system and a power conversion device are interconnected via an interconnection switch. A user load is provided between the power conversion device and the interconnection switch. In parallel with the interconnection switch, a series circuit composed of a load disconnection switch and a voltage maintenance load for maintaining voltage of the user load at the time of system momentary power interruption is connected. Control is performed such that, when momentary power interruption occurs, the interconnection switch is turned off and the power system and the power conversion device are connected via the voltage maintenance load, and at the time of recovery from the momentary power interruption, the interconnection switch is turned on, further the power system and the power conversion device are connected.

Abstract: A self power-generating device for electric vehicles includes a positive charge generating converter, a negative charge generating converter, a transformer and batteries. One end of the positive charge generating converter is provided with a first electrode, the other end of the positive charge generating converter is provided with a second electrode. One end of the negative charge generating converter is provided with a third electrode, the other end of the negative charge generating converter is provided with a fourth electrode. The positive charge generating converter is serially connected to a first capacitor through wire. The negative charge generating converter is serially connected to the second capacitor through wire. The positive charge generating converter, the negative charge generating converter, the first capacitor and the second capacitor form a closed loop and the closed loop is coupled to the primary coil of the transformer to charge the battery.

Abstract: A vehicle cab body for a vehicle includes a cab body structure including a roof structure, side wall structures, and a rear wall structure, wherein the vehicle cab body further includes a vehicle battery, wherein a portion of at least one of the roof structure, side wall structures, and rear wall structure forms at least a part of a housing for the vehicle battery. A vehicle and a vehicle battery arrangement are also provided.

Abstract: There is described a circuit to supply electric power to N electrical panels. The circuit comprises N+1 blockbars, each one of the blockbars being for connection to an automatic transfer switch (ATS) of a power source, each one of the blockbars being connected to at least two other ones of the N+1 blockbars via a segregating switchgear. The circuit further comprises N+1 UPS units, each one of the UPS units being for connection to a dedicated one of the blockbars via a dedicated switchgear. The circuit further comprises 2N power outputs, each one of the N electrical panels being connected to 2 of the 2N power outputs, each one of the 2N power outputs being connected to 2 of the N+1 UPS units. This configuration allows for N+1 redundancy at the generator and UPS levels to feed the electrical distribution with 2N redundancy.

Abstract: Systems and methods for controlling onboard power and communication systems at an automated locker are provided. An example method can include: autonomously detecting a status of a primary power supply connected to the locker, a communication status between the locker and a central server, an internal server status, and an onboard battery percentage of an onboard power; when the onboard battery percentage is greater than or equal to the predetermined battery percentage, autonomously switching to the onboard power and requesting the internal server to conduct transactions and store transaction data internally; and when the battery percentage of the onboard power is lower than the predetermined battery percentage, shutting down the locker; and when the primary power supply is detected to be reestablished and the locker is in communication with the central server, autonomously requesting the internal server to upload the transaction data to the central server.

Abstract: This uninterruptible power supply executes a counter voltage generation mode between a bypass power supply mode and a lap power supply mode. During the counter voltage generation mode, voltage feedforward control is performed for an inverter (2) in accordance with a detection value of a voltage detector (VD5) to generate a counter voltage at one terminal of a switch (S2), the counter voltage being at a level corresponding to a voltage at an output terminal (T4). Therefore, without providing an extra voltage detector for generation of counter voltage, an inrush current can be prevented from flowing from a bypass AC power source (52) to an AC filter (F2) through the switch (S2) when the switch (S2) is turned on.