Abstract: An electrical system for operating an AC electric motor in conjunction with a DC electrical energy storage and a DC electrical energy source is presented. It includes a multi-phase inverter or set of inverters, wherein multiple AC phases of the inverter or inverters are coupled to the motor, and separate DC connections of the inverter or inverters are coupled to the DC electrical energy source and the DC electrical energy storage.

Abstract: A technique for powering gate drivers in a half-bridge configuration uses a single external power supply to power each gate driver. A single on-chip regulator regulates the positive turn-on voltage for each switch. The regulator overhead, is also used as the negative voltage for turn-off, thus transferring the low-frequency variation of the external power supply to the negative turn-off voltage. Accordingly, a single on-chip regulator generates both the positive turn-on voltage and the negative turn-off voltage. In at least one embodiment, reuse of the switch turn-off current further reduces on-chip power dissipation. The on-chip regulator's output filter capacitor discharges during turn-on of the external power switching device. During turn-off, the current that discharges the switch gate capacitance recharges the regulator filter capacitor.

Abstract: The application provides a dispersed carrier phase-shifting method and system. The method includes connecting at least two power modules to form a modular system; each power module including a control module for sampling at least twice a common state variate, signs of slopes of the common state variate at a first and second sampling time are opposite, and a reference time of the first sampling time for each control module is the same; and regulating a carrier frequency of the power module according to a relative size between a sampled values at the first and second sampling time. According to embodiments herein, carrier phase-shifting of modular system may be implemented without communication between respective modules. Under closed-loop control, optimal carrier phase-shifting can be automatically achieved under various duty ratios, thereby having good stability.

Abstract: A testing process for an electrical system is described. The electrical system includes a power converter and a direct current (DC) bus with two or more DC bus terminals and at least one DC bus capacitor. The testing process is a fully automated testing process where a sequence of different diagnostic tests are carried out on the electrical system, each diagnostic test testing one of the power converter and the DC bus to determine if it is responding as expected or operating within normal parameters.

Abstract: A method of operating a multi-phase electric machine includes operating a six-phase machine with six phases that are configured into a first group having a first neutral connection and a second group having a second neutral connection. The method also includes determining whether at least one of the six phases is experiencing a fault. In response to the determining, the method includes combining the first and second neutral connections to form a common neutral connection to continue operating the six-phase machine by using the remaining phase not experiencing the fault.

Abstract: Systems, apparatuses, and methods are described for a power device in a power system. The power device may include a plurality of power stages, which may reduce the number of connectors needed for the power system. The plurality of power stages in the same power device may allow the power device to be configured with additional functionalities.

Abstract: Systems and methods of generating, storing and/or distributing electric power are disclosed. The system may include two or more direct current supercapacitor subsystems, a direct current motor/alternating current generator combination, an electric power distribution network, and supercapacitor recharging elements. One supercapacitor subsystem may power an alternating current generator while the other supercapacitor subsystem charges using a portion of the generated power. Excess power may service other electric loads. The roles of the supercapacitor subsystems may be switched periodically between charging and powering, repeatedly.

Abstract: A device for discharging a DC link capacitor includes a discharge device which is connected in parallel with the DC link capacitor and by which, on receipt of a discharge signal requesting discharge, a current flow can be generated which, in the presence of a first signal state of a control signal, has a lower current intensity than in the presence of a second signal state of the control signal; a voltage detection device by which a voltage signal describing a capacitor voltage dropping across the intermediate circuit capacitor can be generated; and a control device with a signal generating unit which is arranged to generate a reference signal whose value at the time of receipt of the discharge signal is dependent on the voltage signal and is reduced relative to the voltage signal, and a comparison unit which is arranged to compare the voltage signal with the reference signal.

Abstract: In a power conversion device in which cell converters are connected in series, each cell converter includes: main circuit conductors connecting switching elements and a capacitor to each other; a bypass portion disposed between two external terminals connected to other cell converters; external output conductors connecting the external terminals and the main circuit conductors to each other; and bypass connection conductors connecting the external output conductors and the bypass portion to each other. The bypass connection conductors or the external output conductors are disposed so as to oppose each other at a high-potential side and a low-potential side thereof. The conductors are bent so as to have portions at which currents in parts of the conductors have the same direction. Thus, mutual inductances and self-inductances are increased, whereby short-circuit current flowing to the bypass portion at the time of double failures is suppressed.

Abstract: Some embodiments include a high voltage, high frequency switching circuit.

Abstract: A method and apparatus for autonomous rapid shut-down of a power conditioner. In one embodiment, the method comprises determining an amount of active and reactive current generated by a power conditioner; determining whether the amount of active and reactive current satisfies an open circuit threshold; and initiating, when the amount of active and reactive current satisfies the open circuit threshold, deactivation of the power conditioner.

Abstract: A rectifying circuit includes: a voltage-current converting circuit that converts an input voltage into a current; a first transistor and a second transistor that are connected in series and that are connected to a first node into which the current converted by the voltage-current converting circuit flows; a third transistor and a fourth transistor that are connected in series, and that respectively mirror a current flowing through the first transistor and a current flowing through the second transistor; and a first diode that is connected between a second node connected to the third transistor and the fourth transistor, and an output terminal.

Abstract: A power converter according to an embodiment is provided with first to fourth modules, first and second clamp diodes, and first and second buses. The first bus has a first main portion and a first standing portion provided in the first main portion. The first main portion electrically connects the first switching module and the second switching module, and is electrically connected to the first clamp diode. The second bus has a second main portion and a second standing portion provided in the second main portion. The second main portion electrically connects the third switching module and the fourth switching module, and is electrically connected to the second clamp diode. The second standing portion faces the first standing portion.

Abstract: A power conversion device includes: a power conversion circuit for converting DC power into AC power; and a controller to generate a control signal for the power conversion circuit based on a control command value and an output voltage of the power conversion circuit. The controller is configured to generate the control signal based on a corrected voltage command value calculated by subtraction correction to decrease a voltage command value when the output voltage of the power conversion circuit is equal to or higher than a predetermined threshold value, and to generate the control signal based on a voltage command value not subjected to the subtraction correction when the output voltage of the power conversion circuit is lower than the threshold value.

Abstract: Discussed are a power converting apparatus, a photovoltaic module, and a photovoltaic system including the photovoltaic module and the power converting apparatus. The power converting apparatus is capable of converting direct current (DC) power from the solar cell module into alternating current (AC) power, outputting the AC power to a grid, and detecting a signal indicative of abnormality in grid power caused by power cut or the like, thereby preventing an islanding operation.

Abstract: A power conversion apparatus PWCS includes a smoothing capacitance element Cxp connected between a positive terminal and a negative terminal of a power source and configured to smooth a voltage change superimposed on a DC voltage, a switching circuit SWC converting the DC voltage into an AC voltage, a first bus bar BSB1 configured to electrically connect between the positive terminal of the power source and a terminal TCx1 of the smoothing capacitance element Cxp, a second bus bar BSB2 configured to electrically connect between the negative terminal of the power source and a terminal TCx2 of the smoothing capacitance element Cxp, and a filtering capacitance elements C1 and C2 electrically connected between the first bus bar BSB1 and the second bus bar BSB2. The first bus bar BSB1 and the second bus bar BSB2 include opposing portions and are disposed to allow the current to flow through the opposing portions in the same direction.

Abstract: A DC-DC converter including a first power supply including a first converter outputting a first power voltage, a first sensor detecting a panel current from an output of the first converter; and a first output group including a plurality of inverting converters outputting a second power voltage based on the panel current; a second power supply including a second converter outputting the first power voltage, and a second output group including a plurality of inverting converters outputting the second power voltage based on the panel current; and a first phase controller controlling operations of the inverting converters included in each of the first and second output groups based on the detected panel current. The second power supply operates when the panel current exceeds a predetermined enable value.

Abstract: A power management integrated circuit including a reference signal generator, a start-up unit and a supervisory circuit. The supervisory circuit includes an electrical resistance circuit connected between a first end node and a second end node; a power supply input for receiving a supply voltage, this power supply input being connected to the first end node; a low reference potential node; a comparator for comparing a reference voltage value at a first input and a divided voltage value at a second input connected to an internal electrical node of the electrical resistance circuit, the comparator can output a monitoring signal. The supervisory circuit includes a switch controlled by the start-up unit so that the switch is selectively closed and opened based on a detected operational state of the reference signal generator indicating a normal functioning phase of the power management circuit.

Abstract: A large-scale photovoltaic direct current (DC) series boost grid-connected system with a power balancer, including N photovoltaic DC converters and N?1 power balancers, wherein N?2. The output ends of the photovoltaic DC converters are connected successively in series and then connected to the DC grid, and the input ends of the photovoltaic DC converters are respectively connected to the output ends of the photovoltaic power generation unit. Among the photovoltaic DC converters, which are arranged successively in series, a power balancer is disposed between the input ends of two photovoltaic DC converters adjacent to each other. The N?1 power balancers are arranged corresponding to the set N?1 photovoltaic DC converters respectively to balance the input power of the corresponding photovoltaic DC converter, thereby eliminating a difference between the output voltages of the photovoltaic DC converters.

Abstract: A power conversion device, that includes a drive circuit 11a that drives a switching element 4 included in an upper-arm for one of three phases, a drive circuit 11b that drives a switching element 5 included in a lower-arm for the one phase, and a control circuit 9 that transmits a control signal to the drive circuits 11a, 11b, is provided. The power conversion device includes power supply circuits 12a, 12b that provide power to the drive circuits 11a, 11b, respectively, a low-voltage power supply 6 that supplies power to one of the power supply circuits, 12a, and a high-voltage power supply 1 that supplies power to the other of the power supply circuits, 12b. Accordingly, it is possible to reliably protect a system: by realizing minimal redundancy of the power supply, the power supply generation circuit, etc.; and by realizing the short-circuit mode at the time of error occurrence.

Abstract: A diagnosis method for the switching elements in a bidirectional DC-to-DC voltage converter comprising: charging a capacitor in the bidirectional DC-to-DC voltage converter to a predetermined first test voltage, then specifically actuating the switching elements in the bidirectional DC-to-DC voltage converter, and evaluating the voltage in the charged capacitor of the bidirectional DC-to-DC converter to identify a faulty switching element within the switching elements in the bidirectional DC-to-DC voltage converter.

Abstract: A method for arc detection in a system including a photovoltaic panel and a load connectible to the photovoltaic panel with a DC power line. The method measures power delivered to the load thereby producing a first measurement result of the power delivered to the load. Power produced by the photovoltaic panel is also measured, thereby producing a second measurement result of power produced by the photovoltaic panel. The first measurement result is compared with the second measurement result thereby producing a differential power measurement result. Upon the differential power measurement result being more than a threshold value, an alarm condition may also be set. The second measurement result may be modulated and transmitted over the DC power line.

Abstract: A charging/discharging control apparatus includes a motor, an electric drive circuit, a source voltage sampling circuit, a charging/discharging current sampling circuit, and a control chip, where the control chip is configured to send a first pulse width modulation (PWM) drive signal to the electric drive circuit, and the first PWM drive signal instructing the electric drive circuit to store electric energy of an external power supply in an inductor of the motor and charge a battery using the electric energy stored in the inductor of the motor.

Abstract: Methods and systems for connecting a photovoltaic module and an inverter having an input capacitor are presented. The photovoltaic system includes a maximum power point tracking (MPPT) controller coupled between the inverter and the photovoltaic module. The MPPT controller includes a direct current (DC) converter configured to reduce, in a forward buck mode, a voltage of the photovoltaic module, to supply power from the photovoltaic module to the input capacitor of the inverter. The photovoltaic system also includes a microcontroller unit (MCU) configured to control the DC converter to allow the photovoltaic module to operate at a maximum power point, and to increase, in a reverse boost mode, a voltage of the input capacitor of the inverter, to dissipate power from the input capacitor in the photovoltaic module, and the MPPT controller is configured to, based upon one or more triggers.

Abstract: A current limiting control method for a three-level inverter, comprising the following steps: S1. when a current output from a bridge arm is greater than or equal to a current limiting threshold and a received overcurrent signal is enabled, first turning off the main switch transistors and then turning off the auxiliary switch transistors; S2. when the current output from the bridge arm drops to lower than the current limiting threshold and the received overcurrent signal is disabled, turning on the auxiliary switch transistors; S3. when the received overcurrent signal is disabled and a next PWM effective edge of the main switch transistors arrives, turning on the main switch transistors. The present invention relates also to a current limiting control device for a three-level inverter. By implementing the present invention, it is possible to ensure voltage waveform quality and reduce switching loss.

Abstract: The present disclosure relates to a commutation cell and to a compensation circuit for limiting overvoltage across the power electronic switch of the commutation cell and for limiting a recovery current in a freewheel diode of the commutation cell. The power electronic switch has a parasitic emitter inductance. A variable gain compensation circuit generates a feedback from a voltage generated across the parasitic inductance of the emitter of the power switch at turn-on or turn-off of the power electronic switch. The compensation circuit provides the feedback to a control of the power electronic switch to reduce the voltage generated on the parasitic emitter inductance. A power converter including the commutation cell with the compensation circuit is also disclosed.

Abstract: A short-circuit fault detection device detects a short-circuit fault in a step-up and step-down DC-DC converter that takes generated power of a solar cell as an input and outputs a predetermined voltage to a power storage. The DC-DC converter includes a step-up upper arm, a step-up lower arm, a step-down upper arm, and a step-down lower arm. The short-circuit fault detection device includes a voltage detection unit detecting a voltage output to the DC-DC converter from the solar cell, a current detection unit detecting a current output to the power storage from the DC-DC converter, and a controller controlling switching elements constituting the DC-DC converter to determine whether each arm of the DC-DC converter has a short-circuit fault based on a detected voltage value that is a detected value of the voltage detection unit, and a detected current value that is a detected value of the current detection unit.

Abstract: Photovoltaic systems and related techniques are provided. A method for commissioning a photovoltaic (PV) system may include obtaining data describing an arrangement of two or more components of the PV system; performing a test of the PV system, wherein performing the test includes determining whether the PV system complies with at least one PV system criterion based, at least in part, on at least a portion of the data describing the arrangement of the two or more components of the PV system; and in response to determining that the PV system complies with the at least one PV system criterion, activating the PV system and/or notifying a user of the PV system that the PV system complies with the at least one PV system criterion. The method may further include sending information associated with the PV system to a regulatory entity and/or an operator of an electrical grid.

Abstract: The present disclosure relates to a photovoltaic system comprising at least one string of series-connected solar modules and an inverter, a test circuit which can be connected between the string and the inverter in at least one string line, and a testing method in particular for checking whether the inverter-side section of the string lines is closed and whether the inverter is connected.

Abstract: A power supply system is disclosed. The power supply module comprises a three-phase voltage source, for generating a power source with three phases; a plurality of power supply modules, coupled to the three-phase voltage source, each comprising a plurality of major transforming modules corresponding to the three-phase voltage source for generating a plurality of direct-current voltages according to the three-phase voltage source; and at least a backup supply module, coupled to the plurality of power supply modules, each comprising a plurality of backup transforming modules corresponding to the three-phase voltage source, for generating the plurality of direct-current voltages corresponding to the three-phase voltage source by a backup transforming module corresponding to at least one of the plurality of major transforming modules of the plurality of power supply modules when the at least one of the plurality of major transforming modules is in an abnormal operation.

Abstract: The invention relates to a device and method for discharging an energy accumulator (C), in particular an intermediate circuit capacitor, in a high-voltage grid (3), in particular in a direct current intermediate circuit in a motor vehicle, having a direct current converter (5) connected downstream of the high-voltage grid (3), a low-voltage grid (4) connected downstream of the direct current converter (5), an power grid (7) connected downstream of the direct current converter (5) and parallel to the low-voltage grid (4) for supplying energy to a control circuit (9) of the direct current converter (5), and a first controllable switching element (S) which is connected to the connecting line between the direct current converter (5) and the low-voltage grid (4) and by means of which, in the event of a disturbance of the low-voltage grid (4), the direct current converter (5) and the power grid (7) can be disconnected from the low-voltage grid (4).

Abstract: According to an embodiment, a method of controlling an inverter including a rectification unit rectifying inputted AC power to DC power, a smoothing unit smoothing the DC power, and a power conversion unit received the DC power from the smoothing unit to convert the received DC power into AC power having a predetermined size and frequency, the method includes receiving an abnormal signal of the inverter or an electric motor for driving the inverter, determining whether a DC terminal voltage of the smoothing unit is equal to or greater than a low voltage failure level when the abnormal signal is received, determining whether the power conversion unit is operating, and blocking current output of the power conversion unit when the DC terminal voltage is equal to or greater than the low voltage failure level and the power conversion unit is operating.

Abstract: An outlet control system includes a transmitter-detector module having a plug and at least one outlet electrically connected to the plug, wherein the transmitter-detector module is configured to transmit a control signal in response to power being applied to the transmitter plug; and a receiver-switch module comprising a receiver plug and a receiver outlet electrically connected to the plug through a power switch, wherein the receiver-switch module is configured to receive the control signal from the transmitter-detector module and provide a signal to the power switch, such that said power switch is turned on to cause the receiver plug to be connected to the receiver outlet when power is being applied to the transmitter plug and is not turned on when the power is not being supplied to the transmitter plug.

Abstract: In various embodiments, a single-pole switching unit for limiting the energy flow in a series circuit having photovoltaic modules by a pulsating control signal present on at least one DC line is provided. The switching unit may include: a switching element, which is designed to reduce the current flow in the at least one DC line of the photovoltaic modules; a transmission element, which is designed to couple out an electrical control signal present on the DC line and to control the switching element merely with the energy of the coupled-out control signal; and a coupling element, which is arranged in parallel with the switching element and which conducts the control signal through the switching unit when the switching element is nonconducting.

Abstract: A wide dynamic range charger module is configured to couple a variable power source such as a photovoltaic cell to a load. The module determines a maximum power point (MPPT) of the power source and based at least in part upon that MPPT selects one of a plurality of power converters to provide power to the load. The selection is such that the selected power converter is operating within its operating regime. The selected power converter may further be configured to a pre-determined input admittance which corresponds to the power source.

Abstract: An islanding detection apparatus minimizes a reduction in power quality and detects islanding when distributed generations are operated in parallel. Also, another islanding detection apparatus for parallel distributed generations synchronizes parallel distributed generations by periodically applying a reactive current at a half cycle. Further, another islanding detection apparatus for parallel distributed generations easily synchronizes parallel distributed generations even when inverters installed in the respective distributed generations are fabricated through different makers.

Abstract: A redundant path power subsystem comprises a plurality of phase regulators in a multi-phase power converter. The plurality of phase regulators comprises at least N+2 phase regulators. N phases are sufficient to serve an electrical load coupled with the redundant path power subsystem. The redundant path power subsystem also comprises a plurality of power supplies, and a plurality of input and control paths between the plurality of power supplies and the plurality of phase regulators. The plurality of input and control paths comprises a plurality of multiplexing logic devices and a plurality of phase controllers. The plurality of phase controllers is operable to control the plurality of phase regulators. The plurality of multiplexing logic devices is operable to multiplex control signals from the plurality of power supplies and a microprocessor for the plurality of phase controllers.

Abstract: A partition in lattice form forms a plurality of housing sections. A plurality of circuit blocks including a semiconductor block and a terminal base block are electrically connected one to another in a state of being housed in the housing sections to form a power semiconductor circuit. The semiconductor block is formed by covering an IGBT with an insulating material. A collector of the IGBT is connected to an electrode through a metal plate. The electrode is led out from an inner portion of the insulating material to a side surface of the insulating material. A terminal base block includes a power terminal to which an external power wiring for supplying electric power to the IGBT is electrically connected, and a screw hole into which a screw for fixing the power wiring is inserted.

Abstract: In some aspects of the invention, overcurrent protection is carried out by suppressing fluctuations in current flowing through a switching element after overcurrent detection. A peak current reaching time detection circuit detects a peak current reaching time needed until current flowing through a switching element reaches a peak value. A difference voltage detection circuit, including a ½ time detection circuit which detects a time of ½ an ON time of the preceding cycle of the switching element, detects difference voltage between reference voltage used when detecting overcurrent flowing to a load and a signal which has detected current flowing through the switching element for the ½ time. A delay time adjustment circuit, based on at least one of the peak current reaching time and difference voltage, carries out adjustment and control of a delay time occurring until the time when the switching element is turned off after detecting the overcurrent.

Abstract: The present application relates to a cascaded H-Bridge medium voltage drive, a power cell, and a bypass module thereof, wherein the bypass module is configured for bypassing a major circuit module of the power cell, while the major circuit module comprises a fuse, a rectifier, a bus capacitor and an H-Bridge inverter, two points led from the H-Bridge inverter being configured as a first output end and a second output end; a bypass circuit comprises a first bridge arm and a second bridge arm; a point led from the first bridge arm is configured as a first input end of the bypass circuit, a point led from the second bridge arm is configured as a second input end of the bypass circuit, and the first input end is electrically connected with the first output end, the second input end is electrically connected with the second output end.

Abstract: An inverting apparatus and a control method thereof are disclosed herein. The inverting apparatus includes an inverter. The inverter is configured to convert electrical energy to an output current so as to generate an output terminal voltage. When the output current increases, the output terminal voltage increases correspondingly. The inverter includes a control unit. When the output terminal voltage increases and falls within an alert range, the control unit is configured to control the inverter to decrease the output current or maintain the current output current so as to prevent the output terminal voltage from increasing and exceeding a voltage threshold value that causes the inverter to fall into a trip protection mechanism.

Abstract: A drive system for an electric motor includes a connection for a battery, and an inverter having an input side connected to an intermediate circuit and an output side having a connection for an electric motor. The intermediate circuit includes a first thyristor connected in parallel with an intermediate circuit capacitance. The drive system may also include a rectifier having an input side connected at the output side of the inverter in parallel with the electric motor, and a second thyristor connected an output side of the rectifier. The first/second thyristor are configured to be activated by a monitor incorporated in or assigned to the drive system. In the event of a malfunction, the input and/or output side of the inverter can be electrically isolated to allow a multiply redundant armature short circuit.

Abstract: An inverter device includes: an inverter circuit configured to perform ON/OFF operations with a preset duty cycle to convert a DC power into an AC power and output the AC power to an AC motor; and a controller configured to change a duty cycle of the ON/OFF operations.

Abstract: An assembly includes a converter and a controller. The converter has a winding around a transformer core, first and second switches configured to alternately connect respective winding segments to an input power, and first and second resistors respectively connected in series with the switches. The controller is configured to compare voltages corresponding to currents through the resistors and terminate operation of the converter when a difference between the voltages exceeds a threshold indicative of transformer core flux walking.

Abstract: An inverter and an over current protection method thereof are provided. The inverter includes an inverting circuit, a filtering capacitor and an over current protection circuit. The inverting circuit is configured to convert a DC input voltage into an AC output voltage and provide the AC output voltage to a load. The filtering capacitor is coupled to the inverting circuit and the load in parallel. The over current protection circuit is coupled to the inverting circuit and the filtering capacitor and configured to provide an over current protection mechanism. The over current protection circuit detects an AC current on the filtering capacitor and determines whether to enable the over current protection mechanism according to the AC current in order to restrain the power conversion operation of the inverting circuit.

Abstract: A converter device (for power conversion in e.g. a power plant such as a wind turbine is disclosed. An individual controller is provided for each phase of an electrical output power of the converter. If a voltage of one phase is indicated as being out of a predetermined voltage band, an active current of this phase is set to zero and optionally a reactive component of this phase is set to a value that depends on the indicated voltage.

Abstract: A 1, 2 or 3-phase DC to AC converter system for reducing the cost of solar energy installations achieves cost reduction by eliminating low-frequency power transformers. One DC input polarity is selectively switched to an output terminal when the instantaneous AC output from a second output terminal is desired to be of the opposite polarity, while the other DC input polarity is used to form an approximation to a segment of a sine wave of the desired polarity at the second output terminal. A common-mode AC signal is thereby created on the balanced DC input lines at a frequency which is a multiple of 1, 2 or 3 times the AC output frequency and which is useful for detecting ground faults in the DC circuit.

Abstract: The dead time is secured stably in a semiconductor drive circuit for switching devices using a wide band gap semiconductor. The drain terminal of the switching device of an upper arm is connected to the positive terminal of a first power supply, the source terminal of the switching device of a lower arm is connected to the negative terminal of the first power supply, and the source terminal of the switching device of the upper arm is connected with the drain terminal of the switching device of the lower arm. A gate drive circuit provided for each switching device includes an FET circuit and a parallel circuit made of a parallel connection of a first resistor and a first capacitor and having a first terminal connected to the gate terminal of the switching device.

Abstract: A method for operating a converter circuit is provided. The converter circuit includes a converter unit and a transformer. The transformer includes at least one winding set with a primary winding and a secondary winding. The converter unit is connected, on the AC voltage side, to the primary winding of the respective winding set. In order to compensate for undesirable saturation of the transformer, the converter unit is used to deliberately apply a DC voltage to the primary winding of the respective winding set of the transformer.

Abstract: A power supply unit for a press machine having a converter (converter circuit) connected to a commercial AC power supply, and an inverter (inverter circuit) connected to a press motor, includes an electrical energy bank, an inrush prevention circuit, an inrush prevention instruction signal generation section, and a contactor switch section, wherein contactors of the inrush prevention circuit are switched from on ON state to an OFF state and inrush prevention resistors of the inrush prevention circuit are connected to AC phase current paths on condition that the inrush prevention instruction signal generation section has generated and output an inrush prevention instruction signal (Sres) during press operation.