Power converters, and microgrids driven by such a power converter, in which the converter is controlled by a proportional controller which operates directly on AC waveforms, preferably without conversion to a DC type signal; preferably with use of voltage compensation to remove inherent error of proportional controller; and preferably with use of individual phase RMS voltages in the voltage compensation, to allow for normal operation under any load condition. Undervoltage of one or two phases is automatically compensated by adjusting the voltage of all phases, to retain balance. Line-starting of a motor load is automatically detected, and frequency droop is driven, apart from the other control relations in the system, to complete the line-starting operation as quickly as possible.

A converter includes one chip constituted a switching device and a diode. An electronic control unit is configured to calculate a temperature estimated value of the switching device from control conditions of the converter, restrict a control upper-limit value of charge power or discharge power of a battery, when a detection value of a temperature sensor is higher than the temperature estimated value of the switching device, and the detection value of the temperature sensor exceeds a protection temperature of the diode, and restrict a control upper-limit value of charge power or discharge power of the battery, when the detection value of the temperature sensor is lower than the temperature estimated value of the switching device, and the detection value of the temperature sensor exceeds a protection temperature of the switching device.

A converter includes one chip constituted a switching device and a diode. An electronic control unit is configured to calculate a temperature estimated value of the switching device from control conditions of the converter, restrict a control upper-limit value of charge power or discharge power of a battery, when a detection value of a temperature sensor is higher than the temperature estimated value of the switching device, and the detection value of the temperature sensor exceeds a protection temperature of the diode, and restrict a control upper-limit value of charge power or discharge power of the battery, when the detection value of the temperature sensor is lower than the temperature estimated value of the switching device, and the detection value of the temperature sensor exceeds a protection temperature of the switching device.

A VAR dispatch system. A central control system connected to a network is configured to receive data reflecting local variations in conditions on a power grid and to transmit system control commands over the network. A plurality of VAR dispatch devices are connected to the network and to the power grid. Each VAR dispatch device is configured to detect local variations in conditions on the power grid and to transmit the data reflecting such local variations to the central control system and to receive control commands from the central control system. Each VAR dispatch device is configured to store power and to output stored power to the power grid based on local variations in conditions on the power grid. Each VAR dispatch device is further configured to output stored power to the power grid when the VAR dispatch device receives system control commands from the central control system.

A VAR dispatch system. A central control system connected to a network is configured to receive data reflecting local variations in conditions on a power grid and to transmit system control commands over the network. A plurality of VAR dispatch devices are connected to the network and to the power grid. Each VAR dispatch device is configured to detect local variations in conditions on the power grid and to transmit the data reflecting such local variations to the central control system and to receive control commands from the central control system. Each VAR dispatch device is configured to store power and to output stored power to the power grid based on local variations in conditions on the power grid. Each VAR dispatch device is further configured to output stored power to the power grid when the VAR dispatch device receives system control commands from the central control system.

A power supply device includes a power supply, a conversion module, and an electric current sensor, and circuitry. The power supply is to output a voltage that varies in accordance with an amount of electric power output from the power supply. The conversion module includes voltage converters electrically connected in parallel to convert the voltage to a target voltage. The electric current sensor is to detect current supplied from the power supply to the conversion module. The circuitry is configured to determine a number of operating voltage converters among the voltage converters, which are to actually convert the voltage, based on the current detected by the electric current sensor, the voltage, and a representative voltage representing a target range within which the target voltage is included.

A power supply device includes a power supply, a conversion module, and an electric current sensor, and circuitry. The power supply is to output a voltage that varies in accordance with an amount of electric power output from the power supply. The conversion module includes voltage converters electrically connected in parallel to convert the voltage to a target voltage. The electric current sensor is to detect current supplied from the power supply to the conversion module. The circuitry is configured to determine a number of operating voltage converters among the voltage converters, which are to actually convert the voltage, based on the current detected by the electric current sensor, the voltage, and a representative voltage representing a target range within which the target voltage is included.

A power supply system includes a power supply, a conversion module, and a processor. The conversion module includes conversion units to convert, based on a first control signal, voltage of electric power supplied from the power supply. The conversion units are electrically connected in parallel. The processor is configured to change a number of operating conversion unit among the conversion units. The processor is configured to generate the first control signal to generate a DC component in the electric power output from the power supply. The processor is configured to generate a second control signal to detect a state of the power supply. An AC component is generated according to the second control signal in the electric power output from the power supply such that the AC component has an amplitude based on the number of operating conversion unit.

A power supply system includes a power supply, a conversion module, and a processor. The conversion module includes conversion units to convert, based on a first control signal, voltage of electric power supplied from the power supply. The conversion units are electrically connected in parallel. The processor is configured to change a number of operating conversion unit among the conversion units. The processor is configured to generate the first control signal to generate a DC component in the electric power output from the power supply. The processor is configured to generate a second control signal to detect a state of the power supply. An AC component is generated according to the second control signal in the electric power output from the power supply such that the AC component has an amplitude based on the number of operating conversion unit.

A power supply system includes a power supply, a converter, and a processor. The converter converts voltage of the electric power supplied from the power supply. The processor is configured to generate a first control signal to control the converter to output a target voltage or a target current via a feedback control based on the first control signal. The processor is configured to generate a second control signal to detect a state of the power supply. The processor is configured to combine the first control signal and the second control signal to control the converter.