Abstract: An indoor unit included in an air conditioner that includes an outdoor unit includes a power receiving circuit (PR2), a low-frequency transmission and reception circuit as a first reception circuit, a high-frequency transmission and reception circuit as a transmission and reception circuit, and an inner-controller. The low-frequency transmission and reception circuit receives a current signal transmitted from an outdoor unit by using a current loop formed by a power line included in power supply wiring. For a first communication state in which physical connection between with the outdoor unit is recognized and a second communication state in which communication for operation of the air conditioner is performed between with the outdoor unit, the inner-controller selects use of the low-frequency transmission and reception circuit and the high-frequency transmission and reception circuit in the first communication state and the second communication state.

Abstract: Provided is a communication system for an air conditioner including a housing and a control board accommodated in the housing. The communication system includes: a communication conversion unit accommodated in the housing and configured to acquire a required electric signal from the control board and to convert the electric signal into a digital signal for wire transmission; a cable having a first end connected to the communication conversion unit, the cable being drawn out of the housing to outside; and an antenna unit connected to a second end of the cable located outside the housing, the antenna unit being configured to establish wireless communication with a base station.

Abstract: Provided is a communication system for an air conditioner including a housing and a control board accommodated in the housing. The communication system includes: a communication conversion unit accommodated in the housing and configured to acquire a required electric signal from the control board and to convert the electric signal into a digital signal for wire transmission; a cable having a first end connected to the communication conversion unit, the cable being drawn out of the housing to outside; and an antenna unit connected to a second end of the cable located outside the housing, the antenna unit being configured to establish wireless communication with a base station.

Abstract: A power converter includes: a converter circuit converting an alternating current to a direct current; a reactor electrically connected to one of output terminals of the converter circuit; a capacitor electrically connected to the other output terminal of the converter circuit and the reactor; and an inverter circuit electrically connected to the capacitor converting the direct current to an alternating current. The capacitor is a film capacitor. The capacitor and the reactor are mounted on an identical circuit board.

Abstract: A converter, a first switch, a second switch, and an inverter are disposed in that order along a second direction, at a first position in a first direction. A reactor and a capacitor are disposed in that order along the second direction, at a second position in the first direction. Energy is stored in the reactor via the first switch. The capacitor is discharged via the second switch. At least one of a set of the reactor and the converter and a set of the capacitor and the inverter is disposed side by side along the first direction.

Abstract: A converter, a first switch, a second switch, and an inverter are disposed in that order along a second direction, at a first position in a first direction. A reactor and a capacitor are disposed in that order along the second direction, at a second position in the first direction. Energy is stored in the reactor via the first switch. The capacitor is discharged via the second switch. At least one of a set of the reactor and the converter and a set of the capacitor and the inverter is disposed side by side along the first direction.

Abstract: A preheater for a compressor that is capable of heating a lubricant oil efficiently with smaller power is provided. A preheater for a compressor includes: a capacitive oil surface sensor that is provided at a compressor used in a refrigerating cycle, and detects an oil surface of a lubricant oil A in the compressor; and a power supply unit that applies high-frequency voltage to the oil surface sensor.

Abstract: A power converter includes: a converter circuit converting an alternating current to a direct current; a reactor electrically connected to one of output terminals of the converter circuit; a capacitor electrically connected to the other output terminal of the converter circuit and the reactor; and an inverter circuit electrically connected to the capacitor converting the direct current to an alternating current. The capacitor is a film capacitor. The capacitor and the reactor are mounted on an identical circuit board.

Abstract: A discharge switch and a capacitor are connected in series between first and second DC power supply lines. A boost circuit boosts a rectified voltage to charge the capacitor. An inverter receives the rectified voltage as a DC voltage when the discharge switch is not conducting, receives a voltage across the capacitor as the DC voltage when the discharge switch is conducting, converts the DC voltage into an AC voltage, and outputs it to a motor. A switch control unit maintains the discharge switch not conducting over a first time period, and switches the discharge switch between conducting and not conducting in a second time period. A charge and discharge time period setting unit sets the first time period when a rotational speed of the motor is higher than a speed threshold shorter than the first time period when the rotational speed is lower than the speed threshold.

Abstract: Ripple power having a first variation range is input into a DC link (DC power supply lines). Buffer power is provided and received between the DC link and a power buffer circuit, so that the DC link outputs DC power having a second variation range smaller than the first variation range. An inverter receives the DC power as an input, and outputs AC power to a motor. A power control unit controls the power buffer circuit and the inverter on the basis of a compensation rate that sets the second variation range. A compensation rate setting unit performs a setting in which the compensation rate when a rotational speed of the motor belongs to any of a plurality of first predetermined ranges is higher than the compensation rate when the rotational speed belongs to a second predetermined range other than the plurality of first predetermined ranges.

Abstract: Ripple power having a first variation range is input into a DC link (DC power supply lines). Buffer power is provided and received between the DC link and a power buffer circuit, so that the DC link outputs DC power having a second variation range smaller than the first variation range. An inverter receives the DC power as an input, and outputs AC power to a motor. A power control unit controls the power buffer circuit and the inverter on the basis of a compensation rate that sets the second variation range. A compensation rate setting unit performs a setting in which the compensation rate when a rotational speed of the motor belongs to any of a plurality of first predetermined ranges is higher than the compensation rate when the rotational speed belongs to a second predetermined range other than the plurality of first predetermined ranges.

Abstract: A discharge switch and a capacitor are connected in series between first and second DC power supply lines. A boost circuit boosts a rectified voltage to charge the capacitor. An inverter receives the rectified voltage as a DC voltage when the discharge switch is not conducting, receives a voltage across the capacitor as the DC voltage when the discharge switch is conducting, converts the DC voltage into an AC voltage, and outputs it to a motor. A switch control unit maintains the discharge switch not conducting over a first time period, and switches the discharge switch between conducting and not conducting in a second time period. A charge and discharge time period setting unit sets the first time period when a rotational speed of the motor is higher than a speed threshold shorter than the first time period when the rotational speed is lower than the speed threshold.

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: A preheater for a compressor that is capable of heating a lubricant oil efficiently with smaller power is provided. A preheater for a compressor includes: a capacitive oil surface sensor that is provided at a compressor used in a refrigerating cycle, and detects an oil surface of a lubricant oil A in the compressor; and a power supply unit that applies high-frequency voltage to the oil surface sensor.

Abstract: Disclosed herein is a technique for substantially preventing, in a power converter including a boost power factor correction section, the power factor correction section from starting an intermittent operation even if the ripple voltage of its smoothing capacitor has increased. The converter includes: a power factor correction section including a booster circuit boosting an input voltage supplied from a rectifier section and a smoothing capacitor smoothing an output of the booster circuit; and a control section correcting a power factor by controlling the booster circuit. The control section makes correction to the amount of boost of the booster circuit such that an output voltage of the smoothing capacitor does not become lower than the input voltage.

Abstract: A refrigeration device includes a high-voltage electrical parts group having reactors and cooled elements, a low-voltage electrical parts group, a printed wiring board with the electrical parts groups mounted, and a refrigerant jacket that uses refrigerant flowing through the refrigerant circuit to cool the cooled elements. The high-voltage electrical parts group form an interleaved power supply circuit. The cooled elements are placed in an order conforming to a power supply path of the power supply circuit. The power supply circuit has a rectifier circuit, a power factor improvement circuit, smoothing capacitors, and an inverter circuit. The power factor improvement circuit has the reactors connected to each other in parallel and diodes and switching elements serving as the cooled elements connected to each of the reactors. The reactors are placed on an opposite side of the smoothing capacitors, with the diodes and the switching elements sandwiched in between.

Abstract: A failure in the activation, of a motor, caused by external noise superimposed on an induced voltage is reduced. A detection circuit is connected to a connection node provided between an upper-arm switching element and a lower-arm switching element, and detects the induced voltage of a fan motor before activation. The switching controller activates the fan motor in accordance with a result of detection by the detection circuit. While the detection circuit detects the induced voltage, the switching controller performs switching control which involves alternately turning ON and OFF of the lower-arm switching element.

Abstract: Malfunctions of a switching device included in a power factor corrector are reduced when an instantaneous voltage drop or an instantaneous power failure occurs. If the instantaneous voltage drop or the instantaneous power failure occurs in an AC power source while the power factor corrector is performing a power factor correction operation by boosting an input voltage, an instantaneous power failure controller turns off the switching device included in the power factor corrector so that the power factor correction operation stops. When the commercial power source recovers, too, the power factor corrector suspends the power factor correction operation.

Abstract: A converter receives input of an AC voltage, converts the AC voltage into a DC voltage, and applies the DC voltage between a first power line on a positive electrode side and a second power line on a negative electrode side. A snubber circuit has a capacitor provided between the first and the second power lines, and a diode connected in series with the capacitor between the first and the second power lines, and including an anode on a side close to the first power line on the positive electrode side in a series path with the capacitor. An inverter converts the DC voltage into an AC voltage, and applies the AC voltage to an inductive load. An inverter-side current detection unit detects a current that flows through the first power line on the positive electrode side or the second power line on the negative electrode side between the inverter and the snubber circuit.

Abstract: Reduced is occurrence of hunting in which a power factor corrector continuously turns on and off alternately for a short period of time. A power factor correction controller turns on a power factor corrector if a parameter value for an input current into the power factor corrector is greater than or equal to a first threshold, and turns off the power factor corrector if the parameter value is smaller than or equal to a second threshold below the first threshold. Through a predetermined time period from a moment when the power factor corrector is switched either from on to off or from off to on, the power factor correction controller maintains a state of the switched power factor corrector, regardless of the parameter value.