Abstract: A method for controlling a wind turbine which is connected to an electrical grid, detects a grid frequency present in the grid and in the case of which the power output is regulated on the basis of the grid frequency by a controller and, in particular, switches off the power feed into the electrical grid if a limit value of a grid frequency is exceeded, wherein a change in the grid frequency over time is detected, a rate of change is determined and the rate of change is compared with a rate of change limit value and a modified frequency value is used to regulate the power output in the event of the rate of change limit value being exceeded.

Abstract: A power source device has: a storage unit configured to receive a generated power and store as a storage power; a boost unit configured to generate, from a storage power supplied from the storage unit, a boosted power having a higher voltage than a voltage of the storage power, and supply the boosted power to a load; and a voltage detection unit configured to output a boost operation permission signal permitting a boost operation of the boost unit to the boost unit when the storage voltage of the boost unit increases to become a voltage equal to or higher than a minimum operation voltage of the boost unit. The boost unit is configured to start the boost operation by the storage power supplied from the storage unit and operates on the boosted power generated by the boost operation as an operation power source when the boost operation permission signal is output from the voltage detection unit.

Abstract: A method of self-healing power grids after power outages includes providing an Adaptive Restoration Decision Support System (ARDSS) for generating a restoration solution using static and dynamic input data from power generator(s) powering transmission lines, from the transmission lines and loads. At a beginning of a restoration period a two-stage problem is solved including a first and second-stage problem with an optimal planning (OP) function as a mixed-integer linear programming (MILP) problem using initial static and dynamic data to determine start-up times for the power generator and energization sequences for transmission lines involved in the power outage. Only the second-stage problem is again solved with an optimal real-time (OR) function using the start-up times and energization sequences along with updated static and dynamic data to determine operating parameters for the grid.

Abstract: A processor includes a plurality of cores, at least two of which may execute redundantly, a configuration register to store a first synchronization domain indicator to indicate that a first core and a second core are associated with a first synchronization domain, and a power controller having a synchronization circuit to cause a dynamic adjustment to a frequency of at least one of the first and second cores to cause these cores to operate at a common frequency, based at least in part on the first synchronization domain indicator.

Abstract: A memory system includes: a buffer memory device including a reference voltage pad; a memory controller including a controller ZQ pad; and a controller calibration resistor, wherein the reference voltage pad, the controller ZQ pad, and the controller calibration resistor are coupled to each other.

Abstract: Radio-frequency amplification systems, devices and methods. In some embodiments, an amplification system can include a supply circuit configured to provide a high supply voltage in an average power tracking mode. The amplification system can further include an amplifier configured to operate with the high supply voltage and provide an impedance that substantially matches an impedance of a component coupled to an output of the amplifier. The amplification system can further include a signal path configured to route an amplified signal from the output of the amplifier to the component, with the output path being substantially free of an output matching network.

Abstract: An overvoltage protection apparatus and method. The overvoltage protection apparatus includes: a determining unit, having an input end connected to an input end of the apparatus and an output end connected to an input end of a soft-start unit, and configured to determine whether an input voltage at the input end of the apparatus exceeds a preset protection voltage; and the soft-start unit, having an input end connected to the input end of the apparatus and an output end connected to an output end of the apparatus, where if the determining unit determines that the input voltage does not exceed the preset protection voltage and remains stable in a preset delay time, the soft-start unit delivers the input voltage to the output end of the apparatus; and otherwise, the soft-start unit does not deliver a voltage signal to the output end of the apparatus.

Abstract: A method for regulating an electrical power source, comprising the steps of detecting for one or more predetermined conditions associated with a load power of the electrical power source, whereupon the one or more predetermined conditions is detected, acquiring electrical characteristics of the electrical power source to determine a global maximum load power value arranged to approximate a true maximum load power of the electrical power source, and processing the global maximum load power value to determine a local maximum load power value of the electrical power source, wherein the local maximum load power value is arranged to be more accurate in approximating the true maximum load power of the electrical power source when compared with the global maximum load power value.

Abstract: An energy harvesting interface receives an electrical signal from an inductive transducer and outputs a supply signal. An input branch includes a first switch and a second switch connected in series between a first input terminal and an output terminal, and further a third switch and a fourth switch connected in series between a second input terminal and the output terminal. A first electrical-signal-detecting device coupled across the second switch detects a first threshold value of an electric storage current in the inductor of the transducer. A second electrical-signal-detecting device coupled across the fourth switch detects whether the electric supply current that flows through the fourth switch reaches a second threshold value lower than the first threshold value.

Abstract: In a semiconductor device of related art, the degree of freedom when using one pad with plural functions has been disadvantageously low. A semiconductor device has an internal logic circuit, a regulator circuit, and an interface circuit, and the regulator circuit and the interface circuit are coupled to one shared pad. In the case where a driving transistor of the regulator circuit is controlled to be in a conductive state, the shared pad is used as a terminal to which an input voltage of the regulator circuit is input. In the case where the driving transistor of the regulator circuit is controlled to be in a disconnected state, the shared pad is used as an input/output terminal of the interface circuit.

Abstract: A power conversion system includes an input capacitor group, a first-converting circuit, a second-converting circuit, a first filter circuit, a second filter circuit, a third filter circuit and a control circuit. The input capacitor group receives a direct-current-input voltage. The first-converting circuit and the second-converting circuit are connected to the input capacitor group in parallel. The first filter circuit includes a first output inductor and a second output inductor. The second filter circuit includes a third output inductor and a fourth output inductor. The third filter circuit is connected between the first filter circuit and the second filter circuit. The control circuit separately controls the first-converting circuit and the second-converting circuit. The first output inductor is connected to the first-converting circuit, the second-converting circuit and the second output inductor.

Abstract: Advances in the arts are disclosed with novel methods and circuit systems for controlling power in an energy harvesting system. Techniques and related systems for controlling power output of an energy harvesting device provide for monitoring at least one power parameter at a power source and monitoring at least one power parameter at a load such as a storage medium. The power source output is adjusted in order to optimize energy harvesting and/or storage based on real-time performance parameters.

Abstract: A device, system, and method for global maximum power point tracking comprises monitoring an output power of a DC power source while executing a maximum power point tracking algorithm and adjusting a maximum power point tracking command signal in response to the output power being less than a reference output power. The command signal is adjusted until the output power exceeds a previous output power by a reference amount. The command signal may be a voltage command signal, a current command signal, an impedance command signal, a duty ratio command signal, or the like.

Abstract: A power supply system includes: a first battery; a second battery; a voltage converter including a plurality of switching elements; and a controller configured to turn on or off the plurality of switching elements in accordance with pulse width modulation control. The controller is configured to control phases of the pulse width modulation control signals such that the first high-level period of the first pulse width modulation control signal and the second high-level period of the second pulse width modulation control signal do not overlap with each other at a predetermined condition.

Abstract: To minimize excessively high output or increases in magnetic-flux leakage by controlling power feeding on the power-feeding side if an unforeseen situation occurs. This power-feeding device (100) feeds power to an external power-receiving device (150) in a contactless manner. A power-feeding coil (103) uses electromagnetic power to feed electrical power to a power-receiving coil (154) in the power-receiving device (150). While power is being fed from said power-feeding coil (103), a power-feeding-side control unit (107) determines the amount of displacement of the power-feeding coil (103) and, on the basis of the determined displacement amount, controls the amount of electrical power being fed.

Abstract: An output current calculating circuit for a flyback converter operating under CCM and DCM is disclosed. The off current value IOFF and the blanking current value ILEB flowing through a sensing resistor are calculated using a detection module and are summed together using a current summing unit. A voltage converted from the sum value of the off current value IOFF and the blanking current value ILEB is transmitted through an output stage in a predetermined time ratio of a cycle with the duty cycle determined by a logic control unit, in which the logic control unit controls the output stage to receive the voltage converted from sum current in a predetermined time period of each cycle, and prevents the output stage to receive the voltage converted from sum current in the remaining time other than such predetermined time period of each cycle.

Abstract: There is provided an inverter control apparatus, a capacitor being provided on an AC side of the inverter. The apparatus includes a system voltage detector detects a system voltage, a differentiation unit calculates a differential value of the system voltage, a correction current instruction value calculator calculates a correction current instruction value for correcting a current instruction value set for an output current of the inverter, based on the differential value of the system voltage, a current instruction value correction unit corrects the current instruction value, based on the correction current instruction value, and a controller controls the inverter based on the current instruction value.

Abstract: The disclosed embodiments provide a power management system that supplies power to components in an electronic device. The power management system includes a system microcontroller (SMC) and a charger. During operation, the power management system accepts power from at least one of a power adapter and a solar panel. Next, the power management system supplies the power to components in the electronic device without using a converter circuit between the solar panel and the power management system.

Abstract: A control circuit 6 determines whether a difference between an input/output potential difference V11 and an input/output potential difference V13 when bypass switches SW1 and SW2 are again turned on is equal to or smaller than a threshold value Vth2 in a case where the control circuit 6 determines, at normal times other than an engine restart after being idle-stopped, that a difference between the input/output potential difference V11 of a bypass circuit when the bypass switches SW1 and SW2 are turned on and an input/output potential difference V12 when the bypass switch SW1 is turned on and the bypass switch SW2 is turned off is equal to or larger than a threshold value Vth1 and that the bypass switch SW1 has an open fault, and validates the determination of the open fault of the bypass switch SW1 in a case where the control circuit 6 determines that the difference between the input/output potential differences V11 and V13 is equal to or smaller than a the threshold value Vth2.

Abstract: An availability prediction apparatus includes an access section that accesses a storage section and a prediction section. The storage section stores availability specified periods occurred before a present time associated with respective frequencies of the availability specified periods, and the access section acquires the availability specified periods from the storage section. The prediction section predicts at least one target availability specified period within a prediction term, which begins at the present time and ends at a time later than the present time by a predetermined term. The prediction section includes a correlating section that correlates the availability specified periods with candidate periods included in the prediction term, and a selection section that specifies and selects one of the candidate periods having a highest occurrence probability as the target availability specified period.

Abstract: To provide a DC/DC converter which does not need to switch a change direction of a control value depending on a power transmission direction between low voltage side and high voltage side, and can control a voltage of a charge and discharge capacitor. A DC/DC converter which controls voltage of a charge and discharge capacitor by a controller that performs a ?duty control which changes an ON duty ratio difference of semiconductor circuits, and a phase shift control which changes a phase difference of an ON period of semiconductor circuits.

Abstract: Radio-frequency (RF) power amplifiers driven by boost converter. In some embodiments, a power amplification system can include a supply system configured to provide a high-voltage (HV) supply signal based on a battery voltage, and a power amplifier (PA) configured to receive the HV supply signal and amplify an RF signal. The power amplification system can further include an output path configured to route the amplified RF signal to a filter. Such an output path can be substantially free of either or both of an impedance transformation circuit and a band selection switch.

Abstract: A device and a method for controlling a high side DC/DC converter (HDC) of a hybrid vehicle are provided. The switching frequency of the HDC is variably adjusted based on situations of temperatures of an inductor and an IGBT switching element, which constitute the HDC, to maintain a balance between the temperatures of the inductor and the IGBT switching element. Accordingly, temperatures of the inductor and the IGBT switching element are detected, and the switching frequency of the HDC is variably adjusted based on a situation for each temperature of each element to maintain a balance between the temperatures of the inductor and the IGBT switching element, thereby improving the utilization rate of the IGBT switching element.

Abstract: A power converting apparatus includes a rectifier that converts alternating-current power from an alternating-current power supply into direct-current power, a short-circuit unit that short-circuits the alternating-current power supply via a reactor, and a control unit that controls a short-circuit operation of the short-circuit unit. The control unit changes the number of times of the short-circuit operation during a half cycle of the alternating-current power supply on the basis of a load condition and sets a period from a start to an end of the short-circuit operation during the half cycle of the alternating-current power supply after the change of the number of times of the short-circuit operation to be different from a period from a start to an end of the short-circuit operation during the half cycle of the alternating-current power supply before the change of the number of times of the short-circuit operation.

Abstract: Embodiments of the present invention provide a power supply module and a soft start method. The power supply module includes an input detection circuit configured to output a first notification signal to a trigger drive circuit when it is determined that the power supply module receives a power supply signal; the trigger drive circuit configured to, upon receipt of the first notification signal sent from the input detection circuit, wait for a predetermined duration without sending a drive signal to a current limiting circuit, and to send the driver signal to the current limiting circuit when the predetermined duration elapses; and the current limiting circuit configured to limit a current on a Direct Current (DC) bus of the power supply module when the drive signal is not received by the current limiting circuit, and not to limit the current on the DC bus upon receipt of the drive signal.

Abstract: A semiconductor device with a high radiation tolerance is provided. A semiconductor device comprising a semiconductor substrate, a first body region and a second body region provided on a front surface side of the semiconductor substrate, a neck portion provided between the first body region and the second body region, a first source region formed within the first body region and a second source region formed within the second body region, a first gate electrode provided to face the first body region between the first source region and the neck portion, a second gate electrode provided to face the second body region between the second source region and the neck portion, and an insulating film continuously provided between the first gate electrode and the semiconductor substrate, between the second gate electrode and the semiconductor substrate, and on the front surface side of the neck portion, is provided.

Abstract: An electronic system denoising device, includes: a power source, a first signal processing unit, a second signal processing unit and an isolating transformer. The power source is coupled to the first signal processing unit, and to the second signal processing unit via the isolating transformer, and supplies power to the first signal processing unit and the second signal processing unit. The first signal processing unit includes a first signal output end and a first grounded end, and the first signal output end outputs data signals to the second signal processing unit. The first grounded end is coupled to a first ground wire; the second signal processing unit includes a second grounded end coupled to a second ground wire. The electronic system denoising device, via the isolating transformer, avoids impact to the second signal processing unit from ground noise caused by the return current of the first signal processing unit.

Abstract: A motor driving apparatus includes a boosting section, a drive voltage output section, a detecting section, a storage section and a determining section. The boosting section generates a post-boosting voltage by boosting an input voltage. The drive voltage output section generates a drive voltage to drive a motor using the post-boosting voltage. The detecting section detects a value of the input voltage or a variation width relative to a reference value of the input voltage as variation power source variation information when there is power source variation. The storage section stores target value association information associating the power source variation information and a boosting target value of the post-boosting voltage. The determining section determines the boosting target value based on the power source variation information and target value association information. The target value association information is determined based on a range of operations of the drive voltage output section.

Abstract: Provided is a buck converter. The converter includes a power switch configured to receive and switch an input voltage and convert the input voltage into an output voltage, and a switch control circuit configured to generate a signal having a frequency synchronized with the input voltage, compensate for the signal by using an edge threshold voltage in an edge area of the signal according to at least one of a load state and the input voltage, and control switching of the power switch by using a result of comparing the signal with a band voltage corresponding to the output.

Abstract: A current command value in a period from a time when a relay switch is turned on until charging of an inverter capacitor is completed is set to a value smaller than a value corresponding to the smallest one of rated currents of components included in a circuit, and is set to a value smaller than a maximum current value in a safe operating area of a switching element.

Abstract: A power converter (14) can include a switching system (18) to convert a direct current (DC) input voltage to an output voltage based on a switching signal having a duty-cycle. A controller (16) can set the duty-cycle of the switching signal, depending on the DC input voltage, to one of a substantially constant value, such that the output voltage follows the DC input voltage in a normal mode, and a value that varies inversely with respect to the DC input voltage, such that the output voltage is substantially constant in another mode.

Abstract: A sensor fault detection circuit includes: a first amplifier circuit that includes a first pair of elements operating reversely to each other, and amplifies a first sensor signal input from a first voltage amplifier; a second amplifier circuit that includes a second pair of elements operating reversely to each other, and amplifies a second sensor signal input from the second voltage amplifier; and a fault diagnosis unit that detects abnormality of a first voltage signal or a second voltage signal based on the first voltage signal output from the first amplifier circuit and the second voltage signal output from the second amplifier circuit. Characteristics of the first pair of elements are asymmetrical to each other, and characteristics of the second pair of elements are asymmetrical to each other in a same relationship with a relationship of the asymmetry between the characteristics of the first pair of elements.

Abstract: A method of initiating a grid-tied inverter is described, in which in-rush currents and DC overvoltage conditions are reduced or avoided. The method uses a pulse width modulator to drive the inverter under the control of a voltage feedforward signal such that the inverter output is dependent on the measured grid voltage. Then, an AC current feedback controller is enabled and the pulse width modulator is used to drive the inverter under the control of both the voltage feedforward control signal and the feedback control signal.

Abstract: Advances in the arts are disclosed with novel methods and circuit systems for controlling power in an energy harvesting system. Techniques and related systems for controlling power output of an energy harvesting device provide for monitoring at least one power parameter at a power source and monitoring at least one power parameter at a load such as a storage medium. The power source output is adjusted in order to optimize energy harvesting and/or storage based on real-time performance parameters.

Abstract: A power conversion device includes a smoothing capacitor, an input voltage detection unit, a power conversion unit, and a controller. The input voltage detection unit detects a voltage value of the input voltage. The power conversion unit converts a direct-current voltage smoothed by the smoothing capacitor into an alternating-current voltage to output the alternating-current voltage to a power system. The controller has a first operation mode of outputting active power to the power system, has a second operation mode of outputting reactive power to the power system, determines whether or not the voltage value is one of equal to and higher than a determination value, and makes a transition from the first operation mode to the second operation mode within a predetermined time from a time point when it is determined that the voltage value is lower than the determination value.

Abstract: A method for feeding electrical power into an electrical power supply network is described. A configuration for supplying electrical power in the form of DC voltage has been provided and it is connected to the power supply network through an inverter. An MPP tracker (31) has been provided for influencing the inverter, from which an intermediate circuit desired voltage (udc, ref) is determined. A modulation regulator (33) has been provided, from which a given reactive power desired value (Qref) is changed to a reactive power value (Q*). The inverter (17) is influenced by the intermediate circuit desired value (udc, ref) and the reactive power value (Q*).

Abstract: A demand response apparatus receives from a supply resource utilizing apparatus a signal indicating whether power supply from the demand response apparatus to the supply resource utilizing apparatus is possible, estimates a first power usage of the demand response apparatus for a first time interval, changes an operation of the demand response apparatus, estimates a second power usage for a second time interval after the changing of the operation of the demand response apparatus, calculates supply power available to the supply resource utilizing apparatus based on the estimated first power usage and the estimated second power usage, and transmits information about the available supply power to the supply resource utilizing apparatus.

Abstract: A controller (11a) of a DC/DC converter (10a) responsive to power output of a fuel cell power plant (13) operates under a control strategy which determines if fuel cell voltage exceeds a limit, and if so, provided neither fuel cell output current nor DC/DC converter output current is excessive, causes an increase in DC/DC converter duty cycle to thereby increase power demanded from the fuel cell stack. This eliminates the need for conventional voltage limiting to protect fuel cells from corrosion. Digital control loops and state machines are illustrated.

Abstract: Provided are an apparatus and method for minimizing a distribution loss which reconstructs the system construction of a distribution system in consideration of section load characteristics of mutually different distribution system. The apparatus for minimizing a distribution loss which determines a loss calculation period for detecting a loss minimization time point using mutually different distribution systems, calculates loss values of mutually different distribution systems set according to each time point of the loss calculation period, and calculates a total loss value, and selects the mutually different distribution systems one by one during the loss calculation period, and calculates a loss value for specific systems of each distribution system in consideration of a change of a section load in each selected distribution system, determines a loss minimization time point using the specific system loss value of each distribution system and the total loss value.

Abstract: A control unit controls the amplitude of at least either an output voltage or an output current by shifting at least either a first on time or a second on time.

Abstract: A power supply device is responsive to load changes. The power supply device includes a switch control circuit, a charge control circuit, and a discharge control circuit. The switch control circuit controls switches so that electrical power is charged into an inductor, discharged from the inductor, and distributed to first and second capacitors in a time-division manner based on a switching cycle. The charge control circuit controls the amount of electrical power to be charged into the inductor based on a first amount of error between a first output power supply voltage and its target value and a second amount of error between a second output power supply voltage and its target value. The discharge control circuit controls a distribution ratio at which the electrical power discharged from the inductor is distributed to the first and second capacitors based on the ratio between the first and second amounts of error.

Abstract: A signal inverting device generates an inverted signal of an input signal. The device includes a normally-on transistor, a negative-voltage generating unit that generates a negative voltage, and an output terminal. A first terminal of the normally-on transistor is connected to a current source. The output terminal is connected between the first terminal of the normally-on transistor and the current source. The normally-on transistor is turned on/off, by an input of a drive signal to a conduction control terminal of the normally-on transistor. The drive signal is a signal obtained by a synthesis of the input signal and the negative voltage. The inverted signal is output from the output terminal in accordance with the on/off operation of the normally-on transistor. The negative-voltage generating unit generates the negative voltage by rectifying a high-frequency power.

Abstract: A monitoring system and method for monitoring performance of individual powers sources in a distributed power source system. A monitoring module is coupled to each of the power sources, or to each string of serially connected power sources, to monitor and collect data regarding current, voltage, temperature and other environmental factors at the power source. The collected data is transmitted over a power line to a central analysis station for analysis. Data collected from each source indicates malfunction or degradation at the source. Comparison of data collected from adjacent sources filters for environmental factors impacting neighboring sources such as cloudy days for a solar panel. Comparison of data collected from the same source at different times indicates soiling or degradation of the source with time or periodic events such as a moving shade from an adjacent building.

Abstract: A method for optimizing the yield of a photovoltaic array with an inverter is provided. The method includes: a) cyclically measuring a current (Igiv) and a DC link voltage (U) when controlling the inverter by a MPP method (Maximum Power Point) and storing a measured current value, b) lowering the DC link voltage (U) to a value that exceeds by no more than 100% a minimum DC link voltage (Umin) admissible for operation of the inverter, c) measuring a current (Ired) with a reduced DC link voltage and comparing it with a previously stored value at a given time for the current (Igiv), d) if a prescribed threshold for a difference between the two currents (Ired, Igiv) is exceeded, a searching process for a global MPP (Maximum Power Point) is initiated, e) otherwise, operation is continued at a power maximum (MPP) with a last-stored current value for the current (Igiv).

Abstract: A ramp generator for use in readout circuitry includes an integrator coupled to receive a ramp generator input reference signal to generate a reference ramp signal coupled to be received by an analog to digital converter. A power supply compensation circuit that is coupled to generate the ramp generator input reference signal includes a delay circuit including a variable resistor and a filter capacitor coupled to receive a power supply signal. The variable resistor is tuned to match a delay ripple from the power supply to a bitline output. A capacitive voltage divider is coupled to the delay circuit to generate the ramp generator input reference signal. The capacitive voltage divider includes a first variable capacitor coupled to a second variable capacitor that are tuned to provide a capacitance ratio that matches a coupling ratio from the power supply to the bitline output.

Abstract: Controlling a photovoltaic system includes providing a photovoltaic device having a variable DC voltage output and a variable DC current output. The photovoltaic device has a combination of a voltage output level and a current output level corresponding to a predetermined, desired power point. A DC power supply is connected in a parallel and/or series combination with the photovoltaic device. A DC load is connected in series to the combination of the DC power supply and the photovoltaic device such that the load is powered by the combination. A characteristic of the DC power supply is adjusted such that the voltage output and the current output of the photovoltaic device substantially match the voltage output level and the current output level corresponding to the desired power point.

Abstract: A system and method thereof to regulate a current to a capacitive load from a power supply connected to the capacitive load. The system includes a first switch between the power supply and the capacitive load, a super-capacitor configured for charging by the power supply and powering the capacitive load, a current limiting circuit between the super-capacitor and the power supply, a second switch between the super-capacitor and the capacitive load, and a power control circuit configured to control opening and closing of the first switch and the second switch independently, sense a voltage of the power supply, and sense a voltage of the super-capacitor.

Abstract: A method for start control of photovoltaic inverter, a system thereof, and a photovoltaic power generation system are provided. A fan of the photovoltaic inverter is controlled to operate in a case that input voltage of the photovoltaic inverter is greater than a start threshold, and the fan operation is used as a load. Input voltage drop before and after the fan operates is obtained, and in a case that the input voltage drop is less than or equal to a voltage determination threshold, the photovoltaic inverter is controlled to start a grid connection. The voltage determination threshold is changed based on a power determination threshold of the photovoltaic inverter.

Abstract: A fast transient switching voltage regulator includes a reference signal generator to provide a reference in a feedback path to control switching. The reference signal generator is operative to incorporate a voltage offset into the reference signal timed with the control pulses used to control the switching. The voltage offset moves the reference signal out of the way of pulses introduced in the feedback path due to capacitance ESL in the output capacitor of the switching voltage regulator.

Abstract: A method for calculating a solar radiation amount is provided, which enables the prediction of a solar radiation amount with consideration also given to the small movement of a cloud that affects a power generation amount generated by a PV array and thereby improves the accuracy of prediction of the power generation amount generated by the PV array. From a measured output value of a solar panel, solar radiation and a temperature parameter are extracted. An output of a PV is calculated from the extracted solar radiation and temperature parameter. The calculated value is correlated with the measured value. A temperature correction coefficient is obtained so that a correlation coefficient is highest, and a solar radiation amount is calculated using the obtained correlation coefficient.