Abstract: The invention relates to a method for providing power ramp rate control of a hybrid power plant with a plurality of energy assets including wind turbine generators and possibly solar power units, and an energy storage unit. Each energy asset has a ramp rate capability defined as the highest possible ramp rate at a given time, and the method includes receiving from each energy asset the corresponding ramp rate capability, and taking into account the ramp rate capabilities from the energy assets when calculating the power setpoint to each energy asset, so as to improve the power ramp rate control of the hybrid power plant.

Abstract: A load control device for controlling power delivered from a power source to an electrical load may comprise a control circuit configured to control the load regulation circuit to control the power delivered to the electrical load. The control circuit may be configured to operate in an AC mode when an input voltage is an AC voltage and in a DC mode when the input voltage is a DC voltage. The control circuit may be configured to disable the power converter in the DC mode. The control circuit may be configured to render a controllable switching circuit conductive in the AC mode, and non-conductive in the DC mode. The rectifier circuit may be configured to rectify the input voltage to generate a rectified voltage when the input voltage is an AC voltage, and to pass through the input voltage when the input voltage is a DC voltage.

Abstract: A lighting driver includes a negative third harmonic generator configured to generate a negative third harmonic signal corresponding to a third harmonic of an AC input voltage shifted by 180 degrees. The lighting driver further includes an adder circuit configured to generate an adder output signal by adding the negative third harmonic signal to a voltage divider output signal generated from the AC input voltage. The lighting driver also includes a controller configured to control generation of a DC output voltage provided by the lighting driver based on a control signal generated from the adder output signal.

Abstract: The example embodiments are directed to a system and method for dynamically controlling classes of assets in a hybrid generation power plant. In one example, the system may include a plurality of classes of power assets with at least one class comprising a non-renewable power source and at least one class comprising a renewable power source, and a power controller configured to manage a class of power assets from among the plurality of classes, the power controller including a pre-processing module configured to dynamically shape an error being fed into a respective power source of the class of power assets, and an asset control module configured to dynamically adjust a power setpoint of the respective power source of the class of power assets.

Abstract: Disclosed is a switching circuit including an input terminal, a switching terminal, a grounding terminal, a bootstrap terminal, a high-side transistor connected between the input terminal and the switching terminal, a low-side transistor connected between the switching terminal and the grounding terminal, a bootstrap capacitor connected between the switching terminal and the bootstrap terminal, a bootstrap switch connected between a constant voltage line and the bootstrap terminal, and a driver circuit configured to turn on the bootstrap switch in a period of time in which the low-side transistor is on and to turn off the bootstrap switch in a period of time in which the low-side transistor is off. The bootstrap switch includes two P-channel metal oxide semiconductor transistors connected in anti-series with each other between the constant voltage line and the bootstrap terminal.

Abstract: A power converting apparatus includes a first arm including a switching element and a switching element connected in series, a second arm connected in parallel with the first arm and including a switching element and a switching element connected in series, a reactor having one end connected to the switching element and the switching element and the other end connected to a single-phase alternating-current power supply, and a smoothing capacitor connected in parallel with the first arm and the second arm. The power converting apparatus includes a driving circuit driving the switching element, a bootstrap circuit, and a diode adjusting a power supply voltage, wherein a first voltage at which a forward current starts to flow to the diode is lower than a second voltage at which a forward current starts to flow in a body diode formed in the second switching element.

Abstract: There is disclosed new topology for an Electronic Voltage Regulator (EVR) which can apply additive or subtractive (aka boost or buck) voltages to compensate for an increase or decrease in system voltages. This regulator employs a ladder of power capacitors which are in series and connected across the input voltage to apply different levels of voltages to a controlled or regulated transformer. Considering this, the proposed EVR can be utilized as a replacement for conventional electromechanical type on-load tap changers or (OLTCs) commonly used in power transformers, and meant to compensate voltage changes in a system. Electromechanical tap changers have some significant issues, such as defined time durations when switching to different taps, as determined by the spring-loaded mechanism's operation; a high malfunction rate due to mechanical switching when causing arcing, and thereby decreasing the operating lifetime of transformers.

Abstract: Transformer assembly has an input terminal, principal housing with main chamber for high voltage coil(s) having plurality of taps, low voltage coil(s) and retaining oil. An auxiliary housing extends outwardly from principal housing and is fluidly connected to main chamber so that auxiliary housing contains oil. A potential transformer; load tap changer having a controller, a motor and a plurality of switches; electrical wiring connected to taps, switches within auxiliary housing chamber are submerged by oil within auxiliary chamber; load tap change controller can adjust taps while the switches and electrical connections are submerged in oil of auxiliary housing chamber. The upper level of oil in the main housing chamber is at a level equal to or above the switches of the load tap changer. The auxiliary housing has an access opening and cover. System apparatus with frames, having beams, lattices and cable guides for routing cables for assembly.

Abstract: A method includes comparing a ramp signal with an output signal of an error amplifier to determine an initial turn-on time of a boost converter, generating a turn-on time of the boost converter through multiplying the initial turn-on time by a predetermined constant greater than or equal to 1, and maintaining a switching frequency of the boost converter substantially constant through varying a value of the predetermined constant.

Abstract: A method for controlling a power output of a power generating unit includes receiving at least two measurement data sets from a location of integration of a power generating unit to an electrical grid. Each measurement data set includes a plurality of electrical parameters. The method further includes generating a grid model of the electrical grid based on the at least two measurement data sets. The grid model is characterized by an equivalent grid voltage and an equivalent grid impedance. The method further includes computing a strength value of the electrical grid based on the grid model, using the at least two measurement data sets. The method also includes controlling the power output of a power generating unit based on the strength value of the electrical grid.

Abstract: The present disclosure discloses a composite switching circuit, including a plurality of first semiconductor devices connected in series; and at least one second semiconductor device each connected in parallel to one of the plurality of first semiconductor devices. The composite switching circuit is connected to an input source. The second semiconductor device is turned off during a preset period to transfer a current flowing through the second semiconductor device to the first semiconductor devices connected in parallel to the second semiconductor device.

Abstract: Presented herein are embodiments of a power-over-Ethernet (PoE) breakout system that may be used to breakout a PoE port from a PoE information handling system into a number of breakout ports. In one or more embodiments, a PoE breakout system comprises: a PoE port for connecting to a PoE information handling system, such as a PoE switch; a plurality of breakout ports for connecting to powered devices, wherein each breakout port is configured to supply power to a powered device; and a power management module electrically coupled to the PoE port and configured to supply power to each breakout port according to a configuration that sets a power level for that breakout port. In one or more embodiments. the PoE breakout system comprises a data communications module that switches data traffic to a correct PoE breakout port according to its intended powered device.

Abstract: A pulse width modulator PWM circuit and a corresponding method are presented. The PWM circuit receives a control signal and a clock signal. The PWM circuit generates an output signal based on the control signal and the clock signal. The output signal has a first or second signal value. The PWM circuit has a delay circuit to generate, by delaying the clock signal by a delay period, a first enable signal for setting the output signal to the first signal value. The PWM circuit has a ramp generator to generate a ramp signal based on the clock signal. The PWM circuit has a comparator to generate, by comparing the control signal with the ramp signal, a second enable signal for setting the output signal to the second signal value. By delaying the clock signal by the delay period, a minimum on-time of the output signal may be reduced.

Abstract: Electric power conversion devices carry out feedback control, so that a difference between a duty ratio and a duty ratio target value may approach zero, while a duty ratio, which becomes the origin of a drive signal of a semiconductor switching element, is limited by a prescribed upper limit. The control part issues a first operation result, which is limited by a first upper limit, with respect to an operation value which is on an operation process for controlling an output electric power, and further a second operation result which is limited by a second upper limit, which is set as a value higher than the first upper limit, with respect to an operation value. In addition, the control part is configured to carry out the proportional plus integral control, by a difference between the second operation result and a target value of the second operation result.

Abstract: The mill for spice products, in particular such as cinnamon sticks, houses a reservoir for storing the spice product. The reservoir communicates through a passage, with a grinding mechanism. The reservoir includes a mechanism for fragmenting the spice product. The mechanism for fragmenting are defined by a crusher of the spice product.

Abstract: A method of controlling a hybrid power plant connected to a power network, the hybrid power plant having a first renewable energy generator and a second renewable energy generator, the first renewable energy generator being configured to generate power using a different source of renewable energy to the second renewable energy generator. The method comprises: determining a target plant power output for the hybrid power plant; determining a target generator power output for each of the first and second generators based on the target plant power output; determining a respective ramp rate for each of the first and second renewable energy generators based, at least in part, on an attribute of the respective renewable energy generator; and operating each of the first and second renewable energy generators to change its power output to the power network at the determined ramp rate to achieve the target generator power output.

Abstract: An exponential scale pulse width modulation (PWM) controller comprises a waveform generator circuit configured to generate a logarithmic waveform signal that has the shape of an increasing logarithm function; and a first comparator circuit including a first input to receive the logarithmic waveform signal, a second input to receive an input signal, and an output that provides a PWM control signal that includes signal pulses having a duty cycle that changes exponentially with respect to the input signal.

Abstract: A distribution system may include at least one Power Management System (PMS) that controls electrical power distributed transmitted by the distribution system. The system may include a first power station located at an onshore platform. The first power station may include an onshore terminal that distributes electric power to the first power station and to at least one onshore load. The first power station may include various onshore reactors that monitor inbound reactive power received from the onshore terminal or that monitor outbound reactive power sent to a remote location. The system may include a second power station located at an offshore platform which is located at the remote location. The second power station may include an offshore terminal that receives electric power from the first power station and that delivers electric power to at least one offshore load.

Abstract: A control unit of an electric-power conversion apparatus has an input current amplitude command value creation means that creates an input current amplitude command value, which is an amplitude command value of an input current of a first electric-power conversion circuit, in accordance with an output current command value, which is a command value of an output current of a second electric-power conversion circuit, when the output current command value changes; the control unit controls the first electric-power conversion circuit so that an input current follows an input current command value created based on an input current amplitude command value created by the input current amplitude command value creation means; the control unit controls the second electric-power conversion circuit so that an output current follows an output current command value.

Abstract: A power converter module includes a ground terminal, an input voltage terminal confirmed to receive a raw input voltage, and an interconnection terminal configured to provide a regulated output voltage to a load such as a SOC or SIP system to be powered. A voltage regulator is connected to the ground terminal and the input voltage terminal. An inductor has an inductor output connected to the interconnection terminal.

Abstract: A method for controlling a wind power plant including a plurality of wind turbines that provide output power through a transmission line arrangement, wherein each wind turbine in the wind power plant has a nominal power limit setting. The method comprises determining spare capacity on the transmission line arrangement; and configuring one or more of the wind turbines in dependence on the determined spare capacity, such that said wind turbines are operable to exceed their respective nominal power limit setting in order to exploit the spare capacity on the transmission line arrangement. Aspects of the invention also relate to a power plant controller configured to implement the method.

Abstract: Methods and systems for power management using a power converter in transport are provided. In one embodiment, the method includes monitoring a varying AC input to the power converter. The method also includes calculating a power factor adjustment based on the monitored varying AC input. Also, the method includes a power converter controller adjusting the power converter based on the calculated power factor adjustment to cause the power converter to supply a reactive current to a varying AC load.

Abstract: A microgrid control system includes a power transmission system configured to supply power to a microgrid, the microgrid configured to receive power from the power transmission system and to supply power to at least one or more distributed generators or into at least one or more loads, a DC converter configured to convert power that is supplied to the microgrid, and a converter control unit configured to measure a first power frequency variation of the microgrid and a second power frequency variation of the power transmission system and to control active power that is transmitted to the microgrid by the DC converter.

Abstract: Apparatuses and methods for indirect phase variation detection are disclosed herein. An example apparatus may include a clock generator circuit comprising a delay-locked loop (DLL) circuit configured to adjust a phase of a clock signal based on a phase of a feedback clock signal during an initial phase-lock operation. The DLL circuit includes a phase deviation detection circuit configured to detect a variation in a phase of the clock signal based on variations in gate delays of an oscillation circuit, and to initiate a subsequent phase-lock operation in response to detecting variations in the gate delays of the oscillation circuit.

Abstract: A control apparatus performs peak current mode control in which a drive switch is turned off when output of a comparator is inverted during an on-operation period determined by a basic signal. The comparator inverts the output when a reactor current increases to a command current. The control apparatus determines that a switching frequency of the drive switch is required to be switched when the output of the comparator is detected to have not become inverted during the single switching period while the peak current mode control is being performed. The control apparatus sets the switching frequency to a first frequency when the switching determining unit determines that the switching frequency is not required to be switched, and switches the switching frequency from the first frequency to a second frequency lower than the first frequency when the switching determining unit determines that the switching frequency is required to be switched.

Abstract: A switching converter circuit comprises at least an input terminal (IN1) for connecting to a continuous voltage source (VDCbus), an integrated control circuit (20), a pair of field effect transistors (QH, QL) connected to the integrated control circuit (20), a pair of coupled inductors (10) connected to the pair of field effect transistors (QH, QL), a diode (D) connected to the pair of field effect transistors (QH, QL), a pair of capacitors (Cn, Cled), and a first output terminal (OUT1). The converter circuit (1) further comprises a control loop (100) for controlling a current in output from the circuit via the first output terminal (OUT1).

Abstract: Disclosed herein are systems and techniques for adaptive capacitor charge voltage management, particularly for lithium-ion capacitors and hybrid capacitors. The techniques adapt the capacitor charge voltage and hence the capacitor stored energy based on capacitor operating temperature and one or more of the capacitance and the equivalent series resistance (ESR) of the capacitor.

Abstract: The present disclosure relates to a device of monitoring a reactive power compensation system to compensate reactive power, the device including a measurement unit configured to acquire voltage data, current data, and a phase angle from each constituent device, a power performance index calculation unit configured to calculate power performance index data including at least one of power factor data, flicker data, and harmonics data based on the acquired voltage data, current data, and phase angle, and a controller configured to analyze and evaluate the calculated power performance index data based on a preset situation.

Abstract: Systems and methods for an edge of network voltage control of a power grid are described. A system includes a distribution power network, a plurality of loads (at or near an edge of the distribution power network), and a plurality of shunt-connected, switch-controlled volt ampere reactive (VAR) sources also located at the edge or near the edge of the distribution power network where they may each detect a proximate voltage. The VAR source can determine whether to enable a VAR compensation component therein based on the proximate voltage and adjust network VAR by controlling a switch to enable the VAR compensation component. Further still, each of the VAR sources may be integrated within a customer-located asset, such as a smart meter, and a multitude of such VAR sources can be used to effectuate a distributed controllable VAR source (DCVS) cloud network.

Abstract: Aspects and embodiments described herein are directed toward a power interface device including a first power interface configured to couple to an electric utility and a second power interface configured to couple to a microgrid comprising one or more power sources and one or more loads, the one or more power sources including a generator. The power interface device also includes a power conversion circuit coupled to the first power interface and the second power interface and a controller coupled to the power conversion circuit. The controller is configured to allow interfacing between the electric utility operating at a first frequency and voltage and the microgrid operating at a second frequency and voltage by at least detecting an operating frequency of the generator and controlling a power flow between the electric utility and the microgrid based on the operating frequency of the generator.

Abstract: A control method controls a power converter circuit. The power converter circuit includes at least one inductive element (L) storing an output energy, a charging switch (C) for charging the inductive element (L), a releasing switch (R) for releasing the stored output energy from the inductive element (L) and for charging the inductive element (L) with a compensation energy and an output capacitor (Cout) saving the released output energy. The compensation energy is used to achieve Minimized Voltage Switching (MVS) condition when switching on the charging switch (C). A turn on time (te, tdis) of the releasing switch is adjusted by a closed-loop control of a compensation control variable (Vaux) measured in the power converter circuit or of a characteristic value (Vsample) derived from this compensation control variable (Vaux), and a respective power converter circuit.

Abstract: An adaptive power regulation converter for battery powered emergency lighting LED driver is disclosed. The power feedback and power compensation circuits regulate the output power to LED strings and provides tighten regulated constant power and constant lumens for emergency light during power out time. The adaptive power regulation converter can be used for a great range of LED strings.

Abstract: Methods and apparatus to control a weld current amperage are disclosed. A disclosed example method includes identifying an amperage parameter of a welding device, determining a voltage set point based on the amperage parameter and a voltage correction factor, outputting weld current based on the amperage parameter and the voltage set point, comparing a measured voltage corresponding to the weld current to a threshold, and when the measured voltage satisfies the threshold, and adjusting an amperage of the weld current based on the amperage parameter, the voltage set point, and the measured voltage using a first amperage-voltage relationship.

Abstract: An adaptive power regulation converter for battery powered emergency lighting LED driver is disclosed. The power feedback and power compensation circuits regulate the output power to LED strings and provides tighten regulated constant power and constant lumens for emergency light during power out time. The adaptive power regulation converter can be used for a great range of LED strings.

Abstract: A method for controlling and/or closed-loop controlling an electric energy system. Empirical data are provided in a first data storage device for stabilizing the energy system, and a multi-dimensional decision matrix created with a data processing system in a second data storage device. The decision matrix respectively containing as a first dimension derived from the empirical data, system states of the energy system and in the energy system as a second dimension, possible results. Phasor measurement data for current and voltage with a high temporal resolution and a time stamp are obtained with phasor measuring devices distributed in the energy system and used to control the electric energy system. A system state and a result determined by the data processing system using the phasor measurement data and at least one step is selected and automatically carried out for securing the stability of the energy system.

Abstract: Various embodiments include determining an alternating current (AC) voltage and frequency of a supply voltage coupled to a circuit input. The circuit includes a soft starter circuit that is coupled between the circuit input and a first side of an AC motor. A stator winding configuration of the AC motor is determined. A control transformer is configured in response to the AC voltage and frequency, wherein the control transformer is coupled to the circuit input. A jumper device is configured on a second side of the AC motor in response to the stator winding configuration of the AC motor.

Abstract: Apparatuses and methods for indirect phase variation detection are disclosed herein. An example apparatus may include a clock generator circuit comprising a delay-locked loop (DLL) circuit configured to adjust a phase of a clock signal based on a phase of a feedback clock signal during an initial phase-lock operation. The DLL circuit includes a phase deviation detection circuit configured to detect a variation in a phase of the clock signal based on variations in gate delays of an oscillation circuit, and to initiate a subsequent phase-lock operation in response to detecting variations in the gate delays of the oscillation circuit.

Abstract: An apparatus may include a delta-sigma modulator for quantization noise shaping of a digital signal, a digital-to-analog converter configured to generate an analog signal from the digital signal, and an amplifier configured to amplify the analog signal and powered from a charge pump, wherein the charge pump is configured to operate at a switching frequency approximately equal to a zero of a modulator noise transfer function of the delta-sigma modulator, such that the impact of charge pump noise on a total harmonic distortion noise of the apparatus is minimized.

Abstract: A power conversion device has a main switch connected to a positive electrode side line of a battery, at least one semiconductor power element connected between the main switch and a negative electrode voltage line, and an auxiliary circuit having an auxiliary switch, a resonance reactor and an auxiliary diode connected parallel to the main switch. The device further has a voltage detection part which detects an external side voltage of the main switch and a control circuit part performing a switching control of the main switch and the auxiliary switch based on the detection result of the voltage detection part. During the turned-off state of the main switch, the control circuit part turns off the auxiliary switch before the external side voltage of the main switch reaches an input voltage of the main switch. This external side voltage starts to increase when the auxiliary switch is turned on.

Abstract: A device for calculating an average of nonlinear data includes: an input module for receiving a nonlinear function F and nonlinear data y1and y2; a comparison module for deriving nonlinear data c1 and c2 sorted in a descending order, by comparing the nonlinear data y1 and y2; an index module for deriving an index value d1 according to a preset computation, from the sorted nonlinear data c1 and c2; a lookup table (LUT) memory for pre-storing an LUT of the index value d1 and a variable B by using a preset computation formula, and deriving the variable B corresponding to the index value d1 if the index value d1 is received; and a computation module for receiving c1 of the sorted nonlinear data and the variable B and deriving a final nonlinear output value A through the preset computation.

Abstract: The present application relates to power converters, particularly switch mode power converters sharing a load in which the converters are operated to share stresses between them. The application provides a controller (108) in which a stress share control loop (108a, 108b) is provided to ensure the associated converter is operating at an average stress. The stress share control loop has a proportional and an integral term in its feedback path. The integral term may be enabled or disabled. In use, the integral term is enabled in all but one controller.

Abstract: A power compensation apparatus compensates for power of a power system to be allowed to transmit from at least one or more power sources to a load. The power compensation apparatus includes a first system connected to the power system to compensate for active power and reactive power of the power system, a second system connected to the first system to store power necessary for compensating for active power and reactive power, and a third system connected to the second system to generate the power to be stored in the second system.

Abstract: A method for the operation of a pitch system of a wind turbine with at least one rotor blade, wherein the pitch system has at least one input rectifier and at least one pitch drive, each rotor blade can be rotated around its longitudinal axis by the one pitch drive or by at least one of several pitch drives, each input rectifier is supplied with alternating voltage by a supply network, and each pitch drive is supplied with electric power by the one input rectifier or by at least one of several input rectifiers, each pitch drive is connected to an emergency power storage device, whereby each pitch drive can be supplied with electric power by the emergency power storage device that is connected to it.

Abstract: Disclosed herein is a DC/DC power supply apparatus, which includes a plurality of power boards, a control board and a main board. The plurality of power boards are coupled in parallel with one another, and each power board includes a carrier circuit board and a power device disposed on the carrier circuit board. The control board includes a feedback control circuit and a PWM generator circuit; the feedback control circuit is configured to receive one or more feedback signals from the power boards; the PWM generator circuit outputs a PWM control signal to the power boards based on the feedback signal. The main board is electrically coupled to the power boards and the control board.

Abstract: A solar power conversion system includes a photovoltaic array having photovoltaic modules for generating direct current (DC) power. A power converter is provided in the system for converting the DC power to alternating current (AC) power. A transformer is coupled between the power converter and a power grid for transmitting the AC power to the power grid. The transformer is connected to the power grid at the point of common coupling (PCC) and to the power converter at output terminals. A reactance estimation module is provided in the system for estimating a short circuit reactance at PCC based on a small change in a measured voltage at output terminals with respect to a small change in a measured reactive power at the output terminals. Further, a maximum reactive power estimation module estimates a maximum reactive power based on the estimated reactance, the measured voltage at output terminals, and the measured reactive power at the output terminals.

Abstract: A power supply device according to an embodiment comprises a plurality of power sources 10 each including an antenna and an AC/DC conversion unit, a plurality of consolidating units 13_1 to 13_i, and a power supply unit 15. The consolidating units 13_1 to 13_i respectively include consolidating circuits 14_1 to 14_i that selectively consolidate a plurality of DC signals 21_1 to 21_n supplied by the plurality of power sources 10. The power supply unit 15 includes a consolidating circuit 16 that selectively consolidates the DC signals 21_1 to 21_i output from the plurality of consolidating units 13_1 to 13_i, and a voltage conversion circuit 17 that converts a DC signal 23 resulting from consolidation in the consolidating circuit 16, to a predetermined voltage.

Abstract: Driver circuitry is coupled between a power supply and at least one LED in a solid-state lighting fixture, such that a non-isolated direct current (DC) path exists between the power supply and the at least one LED. The driver circuitry is configured to receive an AC input voltage and generate a driver output current for driving the at least one LED from the AC input voltage. By using driver circuitry that is non-isolated from the at least one LED in the solid-state lighting fixture, the efficiency of the driver circuitry may be increased, while simultaneously reducing the cost and complexity of the driver circuitry compared to conventional driver circuitry.

Abstract: A method is disclosed of controlling the operation of a system for providing electrical power to one or more electrical devices, the system comprising an adjustable power source root node and a plurality of adjustable power source remote nodes located remotely from the root node.

Abstract: A detecting method for detecting an output impedance angle of an inverter includes controlling an inverter to output a second voltage signal and a current signal based on a first voltage signal; calculating an active power and reactive power based on the second voltage signal and the current signal; and calculating an output impedance angle of the inverter based on the product of the active power and a first amplitude parameter, the product of the active power and a second amplitude parameter, the product of the reactive power and the first amplitude parameter, and the product of the reactive power and the second amplitude parameter. The first amplitude parameter corresponds to a first amplitude of the first voltage signal, and the second amplitude parameter corresponds to the first amplitude of the first voltage signal and a second amplitude of an AC voltage.

Abstract: According to an embodiment, a power conversion apparatus for a vehicle is provided with a single-phase two-level converter and a single-phase three-level converter. The single-phase two-level converter is composed of a capacitor, first to fourth controllable switching devices, diodes connected in antiparallel with the controllable switching devices, respectively. The single-phase three-level converter is composed of two series-connected capacitors, fifth to tenth controllable switching devices, diodes connected in antiparallel with the controllable switching devices, respectively. The single-phase two-level converter and the single-phase three-phase converter are connected in series at the AC input/output points. The single-phase two-level converter has smaller switching loss than the single-phase three-level converter, and the single-phase three-level converter has higher withstand voltage property than the single-phase two-level converter.