Abstract: The present invention relates to a system and a method for controlling a relay using a flip-flop, in which a flip-flop controlling a relay by receiving a signal of a control unit in a battery management system of a vehicle and supply flip-flop operation power to the flip-flop through a monitoring circuit connected to a battery of the vehicle when operation power of the battery management system of the vehicle is interrupted to maintain a closing state of a relay controlling driving power of the vehicle and to conserve power of the vehicle for a predetermined time.

Abstract: Systems and methods for supplying power at a medium voltage from an uninterruptible power supply (UPS) to a load without using a transformer are disclosed. The UPS includes an energy storage device, a single stage DC-DC converter or a two-stage DC-DC converter, and a multi-level inverter, each of which are electrically coupled to a common negative bus. The DC-DC converter may include two stages in a unidirectional or bidirectional configuration. One stage of the DC-DC converter uses a flying capacitor topology. The voltages across the capacitors of the flying capacitor topology are balanced and switching losses are minimized by fixed duty cycle operation. The DC-DC converter generates a high DC voltage from a low or high voltage energy storage device such as batteries and/or ultra-capacitors. The multi-level, neutral point, diode-clamped inverter converts the high DC voltage into a medium AC voltage using a space vector pulse width modulation (SVPWM) technique.

Abstract: Provided in the present invention are a microgrid control system and a microgrid, the microgrid control system comprising: a grid-connected switch, an energy router, a first controller and a second controller; the first controller controls the grid-connected switch and sends a first control instruction; the second controller receives the first control instruction and responds to the first control instruction for controlling the energy router.

Abstract: A motor drive comprises a rectifier circuit portion arranged to receive an externally supplied AC voltage and to generate a DC bus voltage. An inverter circuit portion is arranged to receive the DC bus voltage (VDC_Bus) and to generate an AC output voltage (Vout) for supply to an external load. A DC bus portion is connected between the rectifier and the inverter. An inductor (L1) is connected in series along a bus conductor between the rectifier and inverter, and a DC link capacitor (C1) is connected in parallel between the bus conductors. A voltage across the DC link capacitor (C1) is input to a tuneable notch filter arranged to supply a filtered signal. A controller varies the resonant frequency of the notch filter to a plurality of values across an operational range and modulates a supply current provided by the inverter with a probe current signal at the resonant frequency.

Abstract: Distributed grid network intelligence enables intelligent local energy storage backup control. A consumer node includes a local energy storage system. A distributed control node for the consumer node monitors local power demand and local energy generation. The control node calculates an interface operation for accessing energy from the local energy storage or charging the local energy storage, based on the local power demand and the local energy generation. The control node triggers a local power converter to execute the interface operation with the local energy storage.

Abstract: A method for controlling a fault of a three phase four wire interlinking converter system according to one embodiment of the present disclosure comprises obtaining a first d-q-o coordinate plane based on an internal phase angle of output voltage produced from each phase of an inverter; converting the first d-q-o coordinate plane to a second d-q-o coordinate plane based on the o-axis configured differently from the first d-q-o coordinate plane; obtaining an output voltage vector for determining a fault location by performing d-q transform on the second d-q-o coordinate plane; determining occurrence of a fault and an area related to the fault based on the output voltage vector; and in the occurrence of the fault, allocating a zero voltage vector to the area related to the fault.

Abstract: A method for optimizing the energy supply from a variable electrical energy source in an electrical facility, operating in a self-consumption mode, connected to an electrical energy distribution network. A control device is configured to control an electrical energy inverter in an electrical facility and to an electrical facility including a control device for controlling an electrical energy inverter.

Abstract: A multi-path converter and a control method thereof are disclosed. The multi-path converter includes a current transfer path using a capacitor and a current transfer path using an inductor such that a current is output to an output end (load) through a plurality of parallel paths, thereby reducing a total RMS current flowing through the inductor, and a control method therefor.

Abstract: An online monitoring system for measuring the on-state voltage drop of power semiconductor devices comprises a voltage withstanding circuit and a voltage clamping circuit, one terminal of the voltage withstanding circuit is connected to one terminal of the voltage clamping circuit, and the other terminals of the voltage withstanding circuit and the voltage clamping circuit are randomly connected to two terminals of the power semiconductor device under test (DUT) respectively. The two terminals of the voltage clamping circuit are output terminals of the online monitoring system. A clamping voltage of the voltage clamping circuit is higher than the on-state voltage drop of the DUT. When the DUT is off, the output voltage of the system is fixed to the clamping voltage, and when it is on, the output voltage is not clamped. The system has simplified structure and enables convenient, accurate and low-cost measurement of on-state voltage drop.

Abstract: A monitoring device for monitoring leakage currents at active conductors has a differential current measurement device, a signal generation device and a control device, which differential current measurement device is designed to record a first signal (I_DIFF) characterizing the differential current of the active conductors and to feed the first signal to the control device. The signal generation device is designed to generate at least one second signal (V_GRID) and to feed the second signal to the control device, which at least one second signal (V_GRID) includes information about the phase angle of a signal occurring at one of the active conductors. The control device is designed to generate a third signal (I_LC_RES) on the basis of the first signal (I_DIFF) and of the at least one second signal (V_GRID), which third signal characterizes the resistive leakage current.

Abstract: A power conversion device of an embodiment includes a power conversion unit, a first capacitor, a gate circuit, a bypass circuit, and a discharging circuit. The power conversion unit includes a plurality of switching elements each having a gate and generates alternating current (AC) power from direct current (DC) power supplied to a provided DC input terminal. The first capacitor is provided on a DC input side of the power conversion unit. The gate circuit includes a drive circuit configured to output a gate drive signal to be supplied to gates of one or more switching elements among the plurality of switching elements and a second capacitor configured to smooth a power supply voltage of power to be supplied to the drive circuit. The bypass circuit causes the second capacitor to be charged with a part of power stored in the first capacitor at the time of power supply loss of a control system circuit and enables the gate drive signal to be maintained in a negative bias by power stored in the second capacitor.

Abstract: A method for controlling a variable speed drive comprising Ni low-voltage power cells connected in series for each phase among multiple phases, i being a phase index. The method comprises repeating P iterations comprising: activating at least one cell of one or more phases and deactivating the other power cells of the variable speed drive, wherein the at least one activated cell is selected on the basis of predefined activation controls depending on an iteration index; and receiving at least one output voltage of the variable speed drive across the terminals of the electrical device for at least one phase. The method further comprises, at the end of the P iterations, determining, from the measured output voltages, values of rectified voltage at the output of respective rectification stages of the power cells, and storing the rectified voltages obtained, which are respectively associated with the power cells.

Abstract: A multiphase interleaved forward power converter includes an inductor and first and second subconverter comprising respective transformers. The converter also includes first and second drives configured to respectively operate the first and second subconverters with cycling periods comprising a conduction period, a reset period, and an idle period. The first and second drives are also configured to phase shift the cycling periods in each subconverter such that the conduction period of the subconverter is at least partially complementary to the idle period of the other subconverter. The second drive also clamps a voltage across a winding of the transformer of the first subconverter to substantially prevent a first resonance voltage from propagating in the first subconverter during the idle period of the first subconverter.

Abstract: A converter assembly including a source connection system comprising a primary source connection, and at least one secondary source connection; a load connection system; a primary source converter including a primary rectifier connected electrically to the primary source connection, and having a boost topology, and a DC link connected electrically between the primary rectifier and the load connection system, the DC link including DC link capacitance; a secondary source converter, which is a direct-current converter having a boost topology, connected electrically between the at least one secondary source connection and the DC link; and a pre-charge converter adapted for pre-charging the DC link capacitance. The pre-charge converter includes a pre-charge direct-current converter having a step down topology.

Abstract: A method of operating a power generator having a first electrical output electrically connected to a utility grid and a second electrical output electrically connected to a load includes detecting if the first electrical output of the power generator is electrically disconnected from the utility grid, and electrically connecting at least a neutral line of the first electrical output to ground in response to detecting that the first output is electrically disconnected from the utility grid.

Abstract: Disclosed herewith is a voltage coordinated control method for an AC/DC distribution system, including steps of: acquiring an actual voltage and an actual current at a DC-side of a converter of the system to obtain a first DC voltage and a first DC current; generating a present reference current signal for the converter according to a voltage-current droop control model, and generating a first control signal to control an output state of the converter; and acquiring an actual voltage at a DC-side of an energy storage adapter in the system to obtain a second DC voltage, generating a present reference power signal for the adapter according to a voltage-power droop control model, and generating a second control signal to control an output state of the adapter.

Abstract: The present invention relates to a functional device (10) powered by a constant current driver (12). The device (10) comprises constant current driver (12), electrical energy storage unit (14), functional unit (16), and control unit (18). The device (10) is controlled by the control unit (18) such that the constant current driver (12) provides a constant current to the functional unit (16) and the storage unit (14) in dependence of a pulse width modulated voltage signal. Current is provided to the storage unit (14) for charging the storage unit (14) during at least part of off periods of the pulse width modulated voltage signal. During on periods of the pulse width modulated voltage signal, current is provided to the functional unit (16) and no current is provided to the storage unit (14). This allows providing the device with a constant current driver with less idle periods and lower current supply.

Abstract: The invention relates to a power system with an electric circuit connected between a power grid and a power source. The electric circuit includes a main power converter having main input terminals connected to the power source 16 by a DC link and output terminals. The main power converter is controlled by a controller. The electric circuit includes a main transformer having a primary winding 8a and a secondary winding, the primary winding being connected to the output terminals of the main power converter. Main switchgear is connected between the secondary winding of the main transformer and the power grid. An auxiliary transformer has a primary winding connected to the power grid in parallel with the main switchgear and a secondary winding connected to the controller. A pre-charge circuit is connected between the auxiliary transformer and the DC link.

Abstract: A power supply current control device including: a current limit value calculation unit configured to calculate a current limit value on a basis of a difference between a power supply voltage and a predetermined set voltage, a power supply current, and a resistance model representing a resistance component of the power supply circuit; a power supply current limit unit configured to limit a magnitude of the power supply current on a basis of the current limit value; a change rate limit value calculation unit configured to calculate a change rate limit value on a basis of the difference and a change speed of the power supply voltage; and a power supply current change rate limit unit configured to limit a change rate of the power supply current on a basis of the change rate limit value.

Abstract: A phase-shifted full bridge (PSFB) switching converter includes a transistor full-bridge having first and second half-bridges. Each half-bridge includes a high-side transistor and a low-side transistor. A controller circuit is configured to generate a drive signal for each transistor. The (first/third and second/fourth) drive signals for the transistors of each half-bridge are periodic with a cycle period, pulse-width modulated and have a temporal offset to each other that equals half of the cycle period. The drive signals for the half-bridges are phase shifted-with respect to one another. The controller circuit also is configured to generate the first drive signal so that the first high-side transistor is switched off when the third drive signal indicates to switch on the second high-side transistor, and to generate the second drive signal so that the first low-side transistor is switched off when the fourth drive signal indicates to switch on the second low-side transistor.

Abstract: A power converter circuit includes a monitoring module that monitors a DC power source, the monitoring module comprising a microcontroller. The power converter circuit also includes a temperature sensor providing temperature data to the microcontroller. In response to an indication from the temperature data of a failure or a problem, the microcontroller changes a parameter of the power converter circuit.

Abstract: An electrical power generating system for providing auxiliary or backup power to a load bus. The system may be used indoors, and generally includes a fuel cell unit comprising a first DC output, an electrical storage unit comprising a DC input coupled to the first DC output of the fuel cell, the electrical storage unit further comprising a second DC output. An inverter coupled to the second DC output receives power, the inverter comprising a first AC output. The system includes a contactor connected between the first AC output and an AC load bus. The AC load bus comprises an AC voltage, and a controller comprising inputs is adapted to sense a phase, a frequency, and a magnitude of the first AC output and the AC voltage and close the contactor when they substantially match.

Abstract: The application discloses an arrangement of switches for a voltage source converter cell, the voltage source converter cell having two AC terminals, wherein the arrangement of switches forms a number of parallel series circuits (branches, current paths), wherein the switches in each of the series circuits paths are being controlled by external signals to alter a conductivity status of the switches between an “ON”-state and an “OFF”-state. The external signals are generated by one or more control units, and the two AC terminals are each connected to subsets of the series circuits of the switches. The control units comprises failure detection means, the failure detection means being adapted to determine a defective switch in the series circuits by predetermined conditions.

Abstract: A power conversion device includes a power converter connected to an electrical storage device that stores DC power, and having a function to convert the DC power stored in the electrical storage device into AC power, and also having a function to output the AC power to one or both of a customer load and a power system; a detection unit that detects voltage and current at a first point on a power line that connects the power converter with the power system; and a control unit that generates a drive command for controlling the power converter based on the voltage and the current detected by the detection unit. The customer load is connected to a second point, on the power line, between the power converter and the first point. The power converter operates on the basis of the drive command generated by the control unit.

Abstract: An information handling system includes active and standby power supplies and a power assist unit. The power supplies provide power to a power rail. The standby power supply supplies current to the power rail when a current demanded by a load is greater than a proportion of a maximum current demand, and is off when the current demand is less than the proportion. The power assist unit is coupled to the power rail and includes a power storage element, a converter coupled to the power storage element and to the power rail, and a controller. The controller receives a current level indication that indicates the current demanded by the load, and in response to the current level indication indicating that the current demand peaks to greater than the proportion of the maximum current demand, directs the converter to provide power from the power storage element to the power rail to prevent the second power supply unit from turning on.

Abstract: In a power conversion device, an inverter (10) of each of three arms (A1 to A3) is controlled such that circulating current (Iz) of three arms (A1 to A3) follows a reference (Izrt) in a test period (times t3 to t4) in which a power system (1) is cut off from the three arms (A1 to A3), and whether the power conversion device is normal is determined based on circulating current (Iz) in the test period. Whether the power conversion device is normal therefore can be determined without affecting the power system (1).

Abstract: A motor drive apparatus includes a converter configured to convert AC power from an AC power supply into DC power and then output the DC power to a DC link, a capacitor provided in the DC link, an inverter configured to convert DC power in the DC link into AC power for motor drive, a discharge circuit which is provided in parallel with the capacitor in the DC link, and is selectively switched between a discharge operation of discharging DC power in the DC link by electrically connecting the discharge circuit and the capacitor to each other, and a non-discharge operation of cutting electric connection between the discharge circuit and the capacitor, and a discharge circuit drive unit configured to perform switch drive of the discharge operation and the non-discharge operation of the discharge circuit by using DC power of the DC link as drive power for the switch drive.

Abstract: A power conversion device includes: power conversion circuitry including a plurality of submodules connected in series to each other; a protection device generating a protection command for protecting each submodule; and one or more relay devices outputting the protection command to each submodule. The relay device includes: a first communication circuit for communicating with the protection device; and a second communication circuit for communicating with the power conversion circuitry. The first communication circuit transmits the stop command to the second communication circuit through a first communication channel, and transmits different information different from the stop command to the second communication circuit through a second communication channel. The communication speed of communication through the first communication channel is higher than that of communication through the second communication channel.

Abstract: A method for operating an inverter and an inverter arrangement including an inverter, and a controller configured to control the inverter to convert DC power into AC power with a DC input voltage control by applying a maximum power point tracking, MPPT, during the converting, in response to the DC power supplied to the inverter exceeding a predetermined power threshold value, control a DC input voltage of the inverter to a lowered value lower than a voltage value corresponding to the maximum power point, and after controlling the DC input voltage of the inverter to the lowered value, control the inverter to convert DC power into AC power with the DC input voltage control by applying the lowered DC input voltage value.

Abstract: A primary side wireless power transmitter inductively couplable to a secondary side wireless power receiver for supplying power to the wireless power receiver for receiving communications from the secondary side wireless power receiver through the inductive coupling comprises a primary side tank circuit receiving a signal on from the secondary side wireless power receiver. A phase delay or time delay circuit generates a fixed delay clock signal. A sample and hold circuit samples a tank circuit voltage utilizing the fixed phase or time delayed clock signal. A comparator is coupled to an output of the sample and hold circuit for extracting data or commands from the signal stream. A method of operating a primary side wireless transmitter inductively coupled to a secondary side wireless power receiver for supplying power to the wireless power receiver to power a load coupled to the receiver is also disclosed.

Abstract: A DC power supply system that limits the number of times of charging/discharging of the storage battery when a DC load is connected to a DC bus line. The system includes a DC bus line connectable to a DC load; a power generation device for supplying electric power to the DC bus line; a secondary battery for supplying electric power to the DC bus line; a DC-AC converter connected between the DC bus line and an AC power system; and a controller that controls power supply from the power generation device, the secondary battery, and the DC-AC converter to the DC bus line, and when the power supply of the power generation device cannot satisfy a power supply request of the DC load, the controller controls the DC-AC converter to supply electric power in preference to the secondary battery from the power system.

Abstract: A power conversion apparatus includes: a plurality of cell blocks connected in cascade; and a plurality of bypass circuits each electrically connected in parallel with a corresponding one of the plurality of cell blocks. Each cell block includes: a first connection node on a high-potential side and a second connection node on a low-potential side for connection to another cell block; and a plurality of cell converters connected in cascade between the first connection node and the second connection node, each of the cell converters including an energy storage device. When a DC fault current flows in the direction from the low-potential side to the high-potential side, the current path via the plurality of cell blocks is larger in impedance than the current path via the plurality of bypass circuits.

Abstract: There is provided a system that includes a processor. The system also includes a memory that stores instructions; when executed by the processor, the instructions configure the processor to perform certain operations. The operations include receiving sensor measurements from an electric power source or device and generating, based on the sensor measurements, a droop control procedure that includes a droop control curve having a non-constant slope. The operations further include regulating a power delivery from the electric power source or device to a bus according to the droop control procedure.

Abstract: A power conversion device includes a plurality of leg circuits and a control device. The plurality of leg circuits correspond to respective phases of an AC circuit and connected in parallel between common first and second DC terminals. Each leg circuit includes a plurality of chopper cells each including an energy storage and cascaded to one another and at least one inductance connected in series to the plurality of chopper cells. The control device controls an operation of only at least one chopper cell included in each leg circuit based on a circulating current which circulates through the leg circuits.

Abstract: A switching power converter is configured to control switching noise by implementing a plurality of pulse width modulation modes of operation. The peak current in each pulse width modulation mode of operation is controlled so that an output power for the switching power converter is continuous with regard to transitions between the pulse width modulation modes.

Abstract: Each of a plurality of specified chopper cells which are some of a plurality of chopper cells included in each leg circuit in a power conversion device is configured as a full bridge. A control device controls operations of first and second switching elements of each specified chopper cell based on a circulating current which circulates through each leg circuit. The control device controls operations of third and fourth switching elements of each specified chopper cell based on a voltage of a capacitor of the specified chopper cell.

Abstract: This motor control device has an inexpensive configuration and enhances motor current target value tracking. This motor control device has an H bridge circuit that has a switching element and is connected to a motor coil provided in a motor, and a control means that drives the switching element at each prescribed PWM period and specifies an operation mode for the H bridge circuit from among a charge mode for increasing the motor current (Icoil) flowing through the motor coil, a fast decay mode for decreasing the motor current, and a slow decay mode.

Abstract: Disclosed embodiments relate to a power monitoring system that may include an external power supply source, an energy storage system, a renewable energy source and a distribution board. In some embodiments, the power monitoring system includes the renewable energy source, the energy storage system, the distribution board, a first power metering device, a second power metering device, a third power metering device, a fourth power metering device and a server.

Abstract: The present application relates to a controller arrangement for controlling an inverter for converting an input power from a power source to a multiphase AC output power provided at a power output of the inverter. The power output is connected to a load and additionally to a power grid. The controller arrangement includes a signal input for receiving a power signal per phase representative of at least one of the power per phase provided to the load or the power per phase provided to the power grid. The controller arrangement is further adapted to control each phase of the multiphase AC output power individually according to the corresponding power signal. The invention further relates to an inverter comprising such a controller arrangement, a power distribution arrangement comprising such an inverter and a controller arrangement to control the inverter and the invention further relates to a method for controlling such an inverter.

Abstract: A power converting device includes a DC-DC converting circuit, a DC-AC converting circuit, and an insulation detecting circuit. The DC-DC converting circuit is configured to convert a DC input voltage to a DC bus voltage. The DC-AC converting circuit is electrically coupled to the DC-DC converting circuit and configured to convert the DC bus voltage to an AC voltage. The insulation detecting circuit is electrically coupled between the DC-DC converting circuit and the DC-AC converting circuit. The insulation detecting circuit is configured to detect a ground impedance value of the power converting device according to the DC bus voltage.

Abstract: A power supply device includes a power switch that is switched according to a gate voltage. A sense resistor receives a switch current that flows through the power switch to develop a sense voltage. A peak of a primary-side current is detected from the sense voltage. The gate driver has a pair of switches for generating the gate voltage in accordance with a control signal. When a low-side switch of the gate driver is turned on according to the control signal, the gate voltage of the power switch decreases as a sink current flows from the gate of the power switch via the transistor.

Abstract: Arrangement for controlling a voltage signal between gate and emitter terminals (G-E) of a switch type power semiconductor component, such as an IGBT transistor, such that the voltage signal is formed at least partly by means of a resistance and a switch (RGON1-SGON1, RGOFF1-SGOFF1) connected in series between an auxiliary voltage (+UG4, ?UG4) of a gate controller and the gate terminal (G) of the IGBT. The arrangement is adapted to control the switch (SGON1, SGOFF1) with a high frequency of at least 1 MHz and with a duty cycle adjusted such that the measured rate of change of a collector voltage of the IGBT being controlled is set in accordance with a reference value received from a control unit of the device.

Abstract: A controller for use in a switched mode power converter includes a comparator coupled to compare an output sense signal representative of an output of the switched mode power converter to a target value. An update clock generator is coupled to generate a clock signal having a clock frequency in response to the output sense signal. A request control is coupled to generate a request signal having a request frequency in response to an output of the comparator and the clock signal to control an operational state of a power switch of the switched mode power converter. A speed at which the request control updates the request frequency of the request signal is responsive to the clock frequency of the clock signal.

Abstract: An adaptive control method for zero voltage switching belongs to the field of integrated circuit. In the present invention, the difference between the turn-on time of the power tube and the time of the lowest drain voltage of the power tube in the switching cycle is quantified by the reversible counter, and the quantized result is transmitted to the next switching cycle to adjust the turn-on time of the power tube through the final count result of the reversible counter, so that the power tube after being adjusted can be turned on when the drain voltage of the power tube is the lowest, thus reducing the switching loss. The present invention can adaptively turn on the power tube when the drain voltage of the power tube reaches minimum, thus, realizing the zero-voltage switching, reducing the switching loss of the switching power supply, widening the application range.

Abstract: Techniques are described to adjust the time when a switch is turned on from the time of one voltage valley to the time of another voltage valley for controlling an average load current or average load voltage. In some examples, the adjustment is instantaneous, and in some examples, the adjustment is gradual. Both of these example techniques provide for high switching efficiency of the switch.

Abstract: In a control device of a power conversion device, an AC control portion generates a first voltage command value representing an AC voltage component to be output from a plurality of chopper cells of each leg circuit. A DC control portion generates a second voltage command value representing a DC voltage component to be output from the plurality of chopper cells of each leg circuit. A circulating current control portion generates a third voltage command value to be output from the plurality of chopper cells of each leg circuit in order to suppress a circulating current. The circulating current control portion performs a non-linear operation with the first, second, and third voltage command values. The plurality of chopper cells of each leg circuit operate in accordance with a result of the non-linear operation.

Abstract: An operation control apparatus includes a criterion calculator that obtains an operation criterion for the power converter, based on the voltage detected by the above voltage detector on the side of the alternating-current power system, a direct-current voltage detector that detects a direct-current output voltage of the solar battery, and an operation determination device that compares the direct-current output voltage detected by the direct-current voltage detector with the operation criterion obtained by the criterion calculator, and supplies the power converter with an operation command if the direct-current output voltage is greater than the operation criterion.

Abstract: Provided are a commutation control method and a commutation control apparatus. The method includes: detecting whether transient disturbance in a DC transmission system satisfies a disturbance criterion condition; when the transient disturbance satisfies the disturbance criterion condition, determining a maximum trigger delay angle used in a commutation operation performed by a current converter on an inverter side of the DC transmission system, the determined maximum trigger delay angle being smaller than a maximum trigger delay angle used before the transient disturbance; and controlling the current converter on the inverter side of the DC transmission system to perform the commutation operation based on the determined maximum trigger delay angle.

Abstract: According to one embodiment, an inverter including a detector which detects a value of an output voltage and a value of an output current; a command value input unit which is capable of receiving a current command value; a current command value compensating unit which, when the value of the output voltage detected by the detector is equal to or lower than a predetermined value, computes a compensation current value for compensating the current command value; an adder which adds the compensation current value to the current command value and outputs the compensated current command value; and a current controller which computes a voltage command value so that a difference between the compensated current command value and the output current detected by the detector becomes zero.

Abstract: A control device (2) of an inverter converts electrical power generated by a solar cell (3) into alternating current power connecting to an electric power system (7). The control device includes: an alternating current voltage sensor (14) sensing a system voltage (Vr) of the electric power system; an MPPT executer (23) controlling a direct current voltage (Vdc) applied to the inverter (1) to cause the electrical power output from the solar cell (3) to be a maximum when the direct current voltage (Vdc) is higher than a lower limit (VL); a direct current voltage lower limit calculator 22 reducing the lower limit (VL) when the system voltage (Vr) is lower than a predetermined voltage; and an electrical power controller (25) controlling reactive power based on the system voltage (Vr), the reactive power being output from the inverter (1).