Abstract: A solar power generation management apparatus which manages a solar power generation system includes: an output sensor that senses respective output current values or output voltage values of a plurality of unit power generation modules; and a calculator that receives sensing information from the output sensor and displays it on a display (50). The calculator acquires the sensing information of the output sensor and simultaneously displays a plurality of display frames (212) corresponding to the plurality of unit power generation modules on the display. Furthermore, it sets a color level of information displayed in the display frame (212) correspondingly to a level of the sensing information. As a result, operating situations of the plurality of unit power generation modules can be visually monitored based on the color levels in the display frames on the display, which enables maintenance timing of solar panels to be visually recognized.

Abstract: A power management method utilizes the steps of reading the driving current; determining if a driving current of an electronic device is less than or equal to a first steady current value for a first period of time; turning off a first electronic module to decrease the driving current when the driving current is less than or equal to the first steady current value for the first period of time; determining if the driving current is within a first judging range for a second period of time; updating the first steady current value with a second steady current value when the driving current is within the first judging range for the second period of time; and determining if the second steady current value is less than or equal to an energy saving set value.

Abstract: A maximum power point tracking (MPPT) device is provided that includes a converter, having a switched mode topology, where the switched mode topology includes a boost topology that establishes a variable transfer ratio between a variable input voltage and a variable output voltage of the converter, where the switched mode topology changes according to a power load on a power generator. The MPPT device further includes a control section, where the control section maximizes an output power of the power generator by controlling the variable transfer ratio, where the MPPT device optimizes an electrical operating point, of the power generator.

Abstract: To enhance the security of a semiconductor device, the semiconductor device has a regulator unit for generating an internal power supply voltage based on a power supply voltage supplied from outside, an internal circuit which operates on the internal power supply voltage, a current detection unit for monitoring a power supply current supplied to the internal circuit, and a control unit for controlling operation of the internal circuit. In the semiconductor device, when the current detection unit detects that the power supply current exceeds a predetermined threshold value, the control unit restricts the operation of the internal circuit.

Abstract: The present invention relates to nonlinear and time-variant signal processing, and, in particular, to methods, systems, and apparatus for adaptive filtering and control applicable to switching power supplies.

Abstract: Disclosed is an LED lighting device using a ballast for a fluorescent lamp, the LED lighting device including: an LED part which includes at least one LED device; a rectifier which rectifies a power signal outputted from the ballast for a fluorescent lamp; and a controller which receives an output signal of the rectifier and controls power transmitted from the ballast to the LED part.

Abstract: The disclosure relates to a tracking method for a voltage transformer, in particular an inverter, of a photovoltaic system. In the method, an intermediate circuit voltage is repeatedly decreased or increased in one direction to a lower or higher voltage by voltage steps of a specified magnitude. The method is characterized in that an average rate of change of the intermediate circuit voltage in a partial time period between two voltage steps is limited by a maximum average rate of change, the maximum average rate of change being defined according to the magnitude of the intermediate circuit voltage. The disclosure further relates to a tracking device designed to perform the tracking method and to an inverter equipped with the tracking device.

Abstract: A system for isolating a first power domain from a second power domain in an integrated circuit includes receiving an input signal from the first power domain and receiving a set of bits from a programmable register. An isolation enable signal indicative of isolating the first power domain from the second power domain is generated, and an intermediate signal based on the isolation enable signal and the input signal is generated. At least one of the input signal, a logic low signal, a logic high signal, and the intermediate signal is output based on the isolation enable signal and the set of bits.

Abstract: An apparatus and a method for power supply are provided. In the invention, the residual standby power can be quickly discharged by an additional fast discharging unit within a predetermined time when an external AC power (for example, city power) received by the power supply apparatus capable of supporting ATX (Advanced Technology eXtended) specification is unavailable (for example, power trip). Accordingly, any host system applied with the inventive power supply apparatus and method would not be inoperable when the received external AC power (city power) is recovered, and thus effectively promoting the stability of the applied host system.

Abstract: A switching regulator that includes a high-side MOSFET, a low-side MOSFET, a high-side driver circuit, a low-side driver circuit, and a capacitive coupling circuit. An output of the high-side driver circuit is coupled to a gate of the high-side MOSFET to control the high-side MOSFET to be substantially depleted during a first operational phase and to be substantially enhanced during a second operational phase. An output of the low-side driver circuit is coupled to a gate of the low-side MOSFET to control the low-side MOSFET to be substantially enhanced during the first operational phase and to provide a regulated drain-to-source current during the second operational phase. The capacitive coupling circuit is coupled to an input of the high-side driver circuit and the gate of the low-side MOSFET and decreases the regulated drain-to-source current during a transition from the first operational phase to the second operational phase.

Abstract: An integrated circuit device, for a power supply that is connected to an AC power source via an input circuit having a capacitor, is able to reliably discharge the capacitor when the AC power source is interrupted. The integrated circuit device includes a first discharge circuit that operates in response to an internal supply voltage and discharges the capacitor via a first switch element that is turned on when the input voltage provided via the input circuit falls below a set voltage, and a second discharge circuit having a second switch element that is turned off when receiving the internal supply voltage but is turned on in response to the input voltage when the supply of internal supply voltage is interrupted.

Abstract: A high voltage sensing unit includes a housing having an internal bore. A resistive voltage divider, including a primary resistor and a secondary resistor configured in series, is included within the housing. A connecting assembly is configured to attach the high voltage sensing unit to a terminal of a high voltage switching device. The connecting assembly provides an electrical connection from the high voltage switching device to the primary resistor and physically supports the high voltage sensing unit. An interface cable provides an electrical connection from the secondary resistor to a receptacle on the high voltage switching device, which can receive a voltage signal and pass the voltage signal to a controller using existing control wiring.

Abstract: A power control device can generate control signals to control operation of power sources. Additional control signals control operation of load switches that can be connected to the power sources to provide secondary sources of power. The load switches can be turned in a gradual manner at rates that depend on the power sources to which they are connected. The outputs of the load switches can be monitored for overvoltage and undervoltage conditions relative to the power sources to which they are connected.

Abstract: In one or more embodiments, an apparatus includes a first power-line communication circuit to communicate data with a second power-line communication circuit over power lines and using a communication protocol requiring that one of the first power-line communication circuit or the second power-line communication circuit join into regular communications in response to an initiation message received over the power lines. The first power-line communication circuit communicates data regularly with the second power-line communication circuit over the power lines after being joined into regular communications by an initiation message received over the power lines, the initiation message being communicated over the power lines at an initiation time interval, the initiation time interval being based on a random interval that is within an interval range and that is based on a relative time at which at least two of the plurality of endpoint devices are designated to join within an interval range.

Abstract: A power supply for a radio frequency (RF) power amplifier that amplifies an RF input signal into an RF output signal and a method of operation in the power supply. The power supply comprises a first power converter to convert an input voltage to the power supply into a first supply voltage of the RF power amplifier. The power supply comprises a second power converter to receive the input voltage and the first supply voltage and to selectively convert either the input voltage or the first supply voltage into at least a portion of a second supply voltage of the RF power amplifier.

Abstract: An electronic device includes a rechargeable battery, an electrical circuit, a battery safety circuit, and a power down mode circuit. The electrical circuit is configured to generate a power mode control signal. The power down mode circuit receives the power mode control signal. If the power mode control signal has a first value, the power down mode circuit is configured to force a voltage at a first port of the battery safety circuit to a voltage value that is less than an under voltage lock out (UVLO) threshold value of the battery safety circuit to transition the electronic device from a normal operating mode to a low current power down mode. The electronic device may further include a wake up mode circuit.

Abstract: In one embodiment, an AC-DC power converter can include: (i) a rectifier bridge and filter to convert an external AC voltage to a DC input voltage; (ii) a first energy storage element to store energy from the DC input voltage via a first current through a first conductive path when in a first operation mode; (iii) a second energy storage element configured to store energy from a second DC voltage via a second current through a second conductive path when in the first operation mode; (iv) a transistor configured to share the first and second conductive paths; (v) the first energy storage element releasing energy to a third energy storage element and a load through a third conductive path when in a second operation mode; and (vi) the second energy storage element releasing energy to the load through a fourth conductive path during the second operation mode.

Abstract: A converter unit to improve overall recovered power in a photovoltaic array configuration. Each photovoltaic panel in the photovoltaic array may be coupled to a respective converter unit, which may include a controller to sense an output voltage and output current produced by the solar panel, and manage the output voltage of a corresponding power converter to optimize and regulate the resultant bus voltage to a point which reduces overall system losses, maintains a low loss condition, and removes series-string non-idealities when the panels are series connected. The controller may also adapt to output condition constraints. Instead of single-port regulation, a combination of input voltage and output voltage management and regulation may be performed within the converter. The source voltage and current characteristic may be shaped to correspond to an optimized power curve at the desired bus voltage to allow MPPT tracking according to the DC voltage bus.

Abstract: A solar electric system comprises photovoltaic elements having integrated energy storage and control, ideally on each PV-panel. The energy storage media may be primary or secondary cylindrical cells interconnected into a battery and/or an array of capacitors (or super-capacitors) and are accompanied by an electronic control circuit which may perform a variety of functions, including but not limited to: power quality control, load following, pulse powering, active line transient suppression, local sensing, remote reporting, wireless or wired communications allowing two way programmable control through local or remote operation. The operation of the system may yield direct current or with the integration of bidirectional micro-inverters create distributed alternating current generation enhanced with energy storage and control two way energy flows between the solar system and the grid.

Abstract: A photovoltaic panel with multiple photovoltaic sub-strings including serially-connected photovoltaic cells and having direct current (DC) outputs adapted for interconnection in parallel into a parallel-connected DC power source. A direct current (DC) power converter including input terminals and output terminals is adapted for coupling to the parallel-connected DC power source and for converting an input power received at the input terminals to an output power at the output terminals. The direct current (DC) power converter optionally has a control loop configured to set the input power received at the input terminals according to a previously determined criterion. The control loop may be adapted to receive a feedback signal from the input terminals for maximizing the input power. A bypass diode is typically connected in shunt across the input terminals of the converter. The bypass diode functions by passing current during a failure of any of the sub-strings and/or a partial shading of the sub-strings.

Abstract: A power tracking device and a power tracking method is disclosed herein. The power tracking device includes a power voltage setting circuit, a switch, a switching signal circuit, and a voltage memory circuit. The switching signal circuit is configured for sending a first control signal to the switch. When the switch receives the first control signal and electrically isolates the power source and the power voltage setting circuit, the voltage memory circuit stores an open circuit voltage of the power source and sends a setting voltage relative to the open circuit voltage, and when the switch receives the first control signal and electrically connects the power source and the power voltage setting circuit, the power voltage setting circuit sets an output voltage of the power source to correspond with the setting voltage.

Abstract: A generated power output measuring apparatus includes a load unit connected to a connecting wire between a power generator using natural energy and a power conditioner configured to supply electric power of the power generator to an external load, the load unit being configured to draw a current from the power generator, a measuring unit configured to measure a voltage and current of the power generator via the load unit, and a control unit configured to increase the current flowing through the load unit and cause the measuring unit to make a measurement when the voltage measured by the measuring unit is in a range of operating voltage of the power conditioner.

Abstract: A power transfer device includes an input terminal, an output terminal, a control unit, and a drive unit. The input terminal can receive an input voltage. The output terminal can provide an output voltage. The control unit can control a switch between the input and output terminals to adjust the output voltage according to the input voltage and a reference voltage, wherein said control unit is deactivated if the reference voltage reaches the input voltage. The drive unit can connect the control unit and the switch if the control unit is activated, and can maintain the output voltage at or near the input voltage if the control unit is deactivated.

Abstract: The present invention relates to an LED lamp (1) adapted for operation with an alternating current. The LED retrofit lamp (1) comprises a LED unit (7, 7?, 7?, 7??) and a compensation circuit with a controllable switching device (9, 9?), connected parallel to said LED unit (7, 7?, 7?, 7??) to provide an alternate current path. A control unit (10, 10?, 10?) is adapted to control said switching device (9, 9?) in a compensation mode in which said switching device (9, 9?) is set to the conducting state for the duration of a shunt period in each half cycle of the alternating current to allow adapting the power/current of the inventive LED lamp (1), so that a versatile and optimized operation of the lamp (1) is possible.

Abstract: A bleeder circuit emulator for use in a power converter to compensate and increase the current demand from the Triac dimmer above its holding current. The circuit includes an input voltage modifier and a leading edge dimming detection circuit. The input voltage modifier receives an input voltage signal that is representative of a magnitude of an input voltage of the power converter and selectively provides a modified input voltage signal to an input of a controller in response to receiving a control signal. The modified input voltage signal is representative of a value that is less than the magnitude of the input voltage. The leading edge dimming detection circuit generates the control signal to engage the input voltage modifier to generate the modified input voltage signal in response to detecting leading edge dimming at an input of the power converter.

Abstract: Disclosed herein is a capacitive discharge welder that comprises a series of super capacitors (or ultra-capacitors) used as a power source. The capacitive discharge welder disclosed herein also comprises a dual function circuit that serves as an emergency stop circuit that is capable of redirecting or disconnecting the weld path in certain applications and situations and a drain circuit to drain a filter capacitor. The capacitive discharge welder disclosed herein is configured to use the super capacitor power supply in a direct discharge configuration as a CD welder. Additionally, the super capacitors are switched at frequency through a filter capacitor to produce a shaped DC welding waveform suitable for a wide variety of welding applications.

Abstract: The present invention discloses a current balancing device and method capable of balancing an output current and an input current of a current loop. Said device comprises: a transmission circuit for outputting an output current and receiving an input current; at least one adjustable resistor set in the current loop for providing resistance according to at least one adjustment signal; and a current balancing circuit, coupled to the transmission circuit and the adjustable resistor, for determining whether the difference between the output and input currents satisfies a predetermined requirement in light of a predetermined duration and thereby generating the adjustment signal, wherein if the difference between the output and input currents fails to satisfy the predetermined requirement, the current balancing circuit will adjust the resistance of the adjustable resistor through the adjustment signal, so as to reduce the difference between the output and input currents.

Abstract: Disclosed is a system for controlling a power-up sequence applicable to a power controller of a lane departure warning system, including: one DC/DC converter unit configured to convert a first input voltage of input power and output the converted first input voltage as a first output voltage, and including four output terminals; and a comparator block unit including two comparators configured to monitor a state of the input power, and one or more comparators configured to generate a control signal for enabling a power output of a next sequence from the first output voltage.

Abstract: A power supply control circuit for a portable electronic device is capable of connecting and disconnecting a power supply with respect to an electrical load of the device. The power supply control circuit offers a relatively quick transition time and low leakage current, making the control circuit particularly suitable for applications that require the power supply to remain connected to the electrical load at all times.

Abstract: A charge and discharge signal circuit includes: high side transistors connected in series; low side transistors connected in series; high side drive circuits; low side drive circuits; and a drive signal generation circuit, wherein each drive circuit includes: a level shifter; a capacitor switch string connected in series, being connected in parallel with the transistor; and a drive part, to which an output of the level shifter is supplied, at least one pair of neighboring ones of the level shifters are commonly formed, and two neighboring ones of the drive parts receive a same output from the common shifters.

Abstract: A power converter is configured to transfer energy from a photovoltaic (PV) array to a DC bus internal to the power converter. The power converter executes a modulation module to selectively connect one or more switching devices between the output of the PV array and the DC bus. The power converter is configured to operate in multiple operating modes. In one operating mode, the converter operates with a fixed modulation period and a variable on time, and in another operating mode, the converter operates with a variable modulation period and a fixed on time. The improved power converter provides highly efficient low power energy capture, improving power efficiency and enabling energy capture in low light conditions with reduced converter losses.

Abstract: A voltage detector operates to detect a system power supply voltage and generate a trigger signal. A control signal generator responds to the trigger signal and generates a control signal. A DC bias generator responds to the control signal by generating a DC bias. The control signal controls the DC bias to have a first value when the power supply voltage is a first voltage and have a second value when the power supply voltage is a second voltage different from the first voltage, wherein the first value is different from the second value. A dynamic DC bias is generated which can not only support a larger voltage scope, but also significantly improves signal to noise ratio. The system power supply detection may concern stop/start operation of an automobile engine.

Abstract: A method and device for setting a processor performance profile for a processor that is unable to directly measure voltage supplied by a voltage regulator includes determining a voltage requested of the voltage regulator and determining a first characteristic of a first portion of the electrical component. The first characteristic is one of power consumed by the first portion of the electrical component and load presented by the first portion of the electrical component. A first current is then determined by using the first voltage, the first characteristic, and a known relationship therebetween. A third voltage that is an estimate of the voltage supplied by the voltage regulator is then determined by comparing the first current to load line characteristics of the electrical component. The third voltage is then used to manage performance of the processor.

Abstract: A powered device is electronically connected to power sourcing equipment (PSE), to receive voltage signals from the PSE. The powered device comprises a rectifier unit, a recognition unit, a control unit, a converter and a powered circuit. The recognition unit identifies that the PSE is an Ethernet PSE or a DC PSE. The control unit controls whether the control unit output a negative voltage signal output by the rectifier unit, according to a positive voltage signal output by the rectifier unit and a identified result output by the recognition unit. The converter converts the negative voltage signal and the positive voltage signal to a working voltage of the powered circuit, to drive the powered circuit. To feed power by a single interface and identify that the PSE is the Ethernet PSE or the DC PSE, according to a simple circuit architecture.

Abstract: A control circuit for controlling a soft-start time of a DC power supply includes a digital potentiometer, a first drive circuit, and a controller. The digital potentiometer includes a first potentiometer. The first drive circuit includes a first driver, a first MOSFET, and a first charge capacitor. The first driver charges the first charge capacitor via the first potentiometer when the DC power supply is first switched on, and the first MOSFET is switched on to connect the DC power supply to the load when the first charge capacitor is fully charged. The controller regulates resistance of the first potentiometer to regulate a charge time constant of the first charge capacitor, enabling a gradual rise in voltage supplied, from approximately zero to full power, within a desired period of time.

Abstract: A system for transferring energy from an energy source includes a first energy source, a DC link coupled to a DC load, a first DC-to-DC voltage converter coupled to the DC link, and a second DC-to-DC voltage converter coupled to the first energy source. A controller is coupled to the first and second DC-to-DC voltage converters and configured to determine a voltage level of the first energy source and of the DC link. If the voltage level of the DC link is less than the voltage level of the first energy source, the controller controls the second DC-to-DC voltage converter to draw energy from the first energy source to cause the DC voltage output from the first energy source and supplied to the first DC-to-DC voltage converter to be below the DC load voltage supplied to the DC link via the first DC-to-DC voltage converter.

Abstract: A level shifter includes: a first cascode portion, including a first transistor of a first conductivity type and a second transistor of a second conductivity type which are cascode-coupled to each other, configured to transmit a first input signal; a second cascode portion, including a third transistor of the first conductivity type and a fourth transistor of the second conductivity type which are cascode-coupled to each other, configured to transmit a second input signal; a latch portion configured to retain a first output signal and a second output signal obtained by changing, based on a first voltage obtained by boosting a power supply voltage, potential levels of the first input signal and the second input signal; and a potential-difference suppression circuit, coupled in parallel to the first cascode portion, configured to control a potential difference between source and drain of each of the first transistor and the second transistor.

Abstract: A battery discharge circuit has a switching circuit and a controller. The switching circuit is coupled between a battery and a load. The controller is configured to generate a control signal to control the switching circuit. When the battery voltage drops below a first reference voltage, the controller adjusts the control signal to regulate the battery voltage to be equal to the first reference voltage.

Abstract: Various embodiments relate to a load driver and a luminaire including the load driver. The load driver may include a voltage limiting circuit including a first polar capacitor and a second polar capacitor connected in inverse series, which are connected in parallel respectively with first and second current limiting elements, where the first and second current limiting elements limit the direction in which current flows so that current flows through different polar capacitors in positive and negative halves of a cycle of an alternating-current power supply.

Abstract: Provided is a maximum power extraction devices including: a battery; a voltage control unit adjusting a size of a first power outputted from the battery according to a resistor selected from a plurality of resistors, and generating a compare signal according to a size difference between an operating voltage adjusting the size of the first power depending on the selected resistor and a reference voltage; a switching unit connected between the battery and a load and adjusting a size of the operating voltage according to a size difference of the compare signal in response to first and second switching control signals; a switching control unit generating the first and second switching control signals to allow a size between the operating voltage according to the compare signal and the reference voltage to be within an error range; and a maximum power control unit measuring the number of first operations obtained by counting the occurrence number of the first or second switching control signals for a predetermined

Abstract: The present invention employs system and method in for distinguishing between power capabilities of various external power sources and a system that can communicate the identified power capabilities to the secondary side of the wireless power transfer system. Once the secondary side of the wireless power transfer system receives the power capability information, it adjusts the current available for a payload in accordance with the information received on power source capabilities.

Abstract: A DC-DC converter includes a zero current detector. The DC-DC converter includes a high-side switch and a low-side switch. When the DC-DC converter works in a discontinuous conduction mode (DCM). The zero current detector detects a zero current a detection node which is arranged between the high-side switch and the low-side switch generates the zero current, the zero current detector outputs the control signal to a driver. The driver switches the high-side switch and the low-side switch off simultaneously according to the control signal. The zero current detector includes a temperature compensation unit to control a responsivity of the zero current detector which not influenced by temperature change.

Abstract: A high power density switched-capacitor DC-DC converter is disclosed. According to one aspect, the subject matter described herein includes a high power-density switched-capacitor DC-DC converter that includes: first and second voltage summing circuits, each voltage summing circuit producing an output voltage that is substantially equal to an input voltage; and a switching circuit connected between the first and second voltage summing circuits and configured to provide a DC voltage source as an input to the first and second voltage summing circuits, wherein the converter produces an output voltage that is the sum of the voltage produced by the first voltage summing circuit, the voltage provided by the DC voltage source, and the voltage produced by the second voltage summing circuit.

Abstract: A circuit includes a reference circuit configured to receive a reference input voltage and provides a first output signal that is a function of the reference input voltage. The circuit includes a reference adjuster configured to receive an external input signal and generates a second output signal that is a function of the external input signal to control an offset voltage to adjust the first output signal. The first output signal and the second output signal are combined to provide a dynamic reference output signal. If the external input signal has crossed a predetermined threshold, the dynamic reference output signal tracks the external input signal while maintaining a substantially constant voltage difference relative to the external input signal.

Abstract: A protective circuit for a process control device such as a valve actuator, for example, prevents damage to device components. In particular, a protective circuit allows an analog current loop (e.g., 4-20 mA) to provide to a device component a secondary operating voltage, derived from the analog current loop, in the absence of a primary operating voltage source (e.g., during a power failure), such that the device component is not damaged when a signal from the analog current loop is applied to the process control device in the absence of the primary operating voltage source.

Abstract: A regulator draws power from a battery or power delivery system and supplies regulated power to a load according to alternating modes of operation. In a voltage control mode, the regulator supplies power with a nominal voltage level and a fluctuating current level that is allowed to float according to the current demands of the load. When the load demands an amount of current that could potentially cause damage, the regulator transitions to a current control mode. In the current control mode, the regulator supplies power with a fluctuating voltage level and a maximum current level. The regulator transitions between voltage control mode and current control mode in order to supply a maximum power level to the load without exceeding the maximum current level. The regulator is also configured to limit the power drawn from the battery by decreasing the maximum output current, potentially avoiding voltage droop.

Abstract: An output control apparatus of a solar cell is provided with: a first controlling device for sequentially increasing a load for extracting the output from a load in an increase area in which the output increases with respect to an increase in the load; a detecting device for detecting a decrease in the output with respect to the increase in the load in a process of sequentially increasing the load; and a second controlling device for rapidly reducing the load to an initial load which belongs to the increase area in comparison with the process of sequentially increasing the load in cases where a change in the output is detected, the first controlling device sequentially increasing the load again after the load is reduced to the initial load.

Abstract: Representative implementations of devices and techniques provide a dimming arrangement for a variable load, such as a lamp. The dimming arrangement is coupled to a drive circuit for the load and arranged to reduce a drive current associated with the drive circuit, based on a control voltage.

Abstract: A current sensing circuit may include a shunt resistance through which current to be sensed travels. A first and a second differential amplifier may each provide an amplified output of the voltage across the shunt resistance. A switching system may deliver a current sensing signal output based on the amplified output of the first differential amplifier when the common mode voltage across the shunt resistance is low and based on the amplified output of the second differential amplifier when the common mode voltage across the shunt resistance is high. The first differential amplifier may provide its lowest output DC offset voltage when the common mode voltage is low, while the second differential amplifier may provide its lowest output DC offset voltage when the common mode voltage is high. The first and second differential amplifiers may both have a low common mode voltage rejection ratio, such as a ratio of less than 40 db at the switching frequency of switches that control the current that is sensed.

Abstract: According to one embodiment, a control device communicates with a power measurement device. The control device includes a communication unit, a threshold storage, a calculation unit, and a control unit. The communication unit is configured to receive a usable electric power from the power measurement device. The threshold storage stores a first threshold. The calculation unit is configured to calculate a usable electric energy by integrating the usable electric power. The control unit is configured to change an operation status of the control device based on a comparison result between the usable electric energy and the first threshold.