A drive includes an inverter power circuit that applies power to an electric motor of a compressor from a direct current (DC) voltage bus. A power factor correction (PFC) circuit outputs power to the DC voltage bus based on input alternating current (AC) power. The PFC circuit includes: (i) a switch having a first terminal, a second terminal, and a control terminal; (ii) a driver that switches the switch between open and closed states based on a control signal; (iii) an inductor that charges and discharges based on switching of the switch; and (iv) a circuit that outputs a signal indicating whether the switch is in the open state or the closed state based on a voltage across the first and second terminals of the switch.

Provided is an air conditioning apparatus that is capable of suppressing increases in volume and cost of the apparatus and performing more suitable overheating protection. An electric compressor is an inverter-integrated electric compressor integrally including a compressor, an electric motor that drives the compressor, and an inverter including a temperature sensor that detects the temperature in the vicinity of a semiconductor switching device, wherein a controller estimates a discharge temperature of the compressor on the basis of a correlation of respective pressure loading characteristics for the detected temperature of the inverter, for the rotational speed of the compressor, and for the motive force of the compressor in a refrigerating cycle.

A control device and method for preventing the start and stop of heat source machines from being frequently repeated. The control device determining whether or not basic conditions for decreasing the number of machines are satisfied when the number of currently operating machines is increased by one is determined if a current operational status satisfies basic conditions for increasing the number of machines, and one heat source machine is started if it is determined that the basic conditions for decreasing the number of machines are not satisfied, and determining whether or not the basic conditions for increasing the number of machines are satisfied when the number of currently operating machines is decreased by one are satisfied if a current operational status satisfies the basic conditions for decreasing the number of machines, and one heat source machine is stopped if it is determined that the basic conditions for increasing the number of machines are not satisfied.

Reliability of devices such as lighting fixtures, is improved by replacing an inductor based voltage inverter to power the device with a switching constant current PWM controller. Avoiding use of an inductor and matching capacitor is made possible by a high voltage power input that exceeds the voltage requirements of the device. The power is pulse width modulated with a current feedback to control duty cycle, and thus average device current.

An air conditioner includes an inverter circuit, a control unit that controls the inverter circuit, a compressor having a protection device (a pressure switch), and a phase-voltage detection circuit (a U-phase voltage detection circuit) that detects a voltage at any of three-phase windings (compressor windings) of the compressor. The control unit includes a shutdown-cause specifying unit that determines presence or absence of an operation of the protection device based on a phase voltage value detected by the phase-voltage detection circuit, by turning on any of a plurality of switching elements constituting the inverter circuit, after the compressor has been shut down, and specifies a cause of the shutdown of the compressor.

A motor drive control device includes a three-phase rectifier; a boosting circuit including a reactor, a switching element, and a backflow preventing element and boosts a direct-current bus voltage supplied from the three-phase rectifier; a smoothing capacitor; an inverter circuit; a boosting control unit; an inverter control unit; and a circuit protecting unit suppresses a ripple current flowing through the smoothing capacitor. In the circuit protecting unit, a correlation of an on-duty ratio of the switching element included in the boosting circuit, the output power of the inverter circuit, and an estimated ripple current are set. On the basis of the on-duty ratio of the switching element, output power of the inverter circuit, and the correlation, the circuit protecting unit determines an estimated ripple current flowing through the smoothing capacitor. When the estimated ripple current exceeds a preset threshold, the circuit protecting unit suppresses the ripple current.

A controller of an inverter control apparatus includes an A/D conversion unit that performs digital conversion of an input signal when a signal for either an A/D converter start trigger or an A/D converter start trigger is input thereinto; a first inverter control unit that generates the A/D converter start trigger which starts the A/D conversion unit, based on A/D converter start timing information and a first carrier signal; a second inverter control unit that generates the A/D converter start trigger which starts the A/D conversion unit, based on A/D converter start timing information and a second carrier signal; and an A/D start factor selection unit that receives either the A/D converter start trigger or the A/D converter start trigger and selects an A/D start factor at a predetermined period timing of an operation period of the first carrier signal and the second carrier signal.

Provided is an inverter for reducing electric power consumption and noise. The inverter comprises: a driving unit including three switching elements included in an upper arm and connected in a three-phase bridge configuration and three switching elements included in a lower arm and connected in a three-phase bridge configuration, and converting input direct current power into three-phase alternating current power and then outputting the alternating current power to a three-phase load; and at least one processor for maintaining one of the three switching elements, which are included in the upper arm, in an on-state in a first period, maintaining one of the three switching elements, which are included in the lower arm, in an on-state in a second period, and driving the driving unit in a two-phase modulation method by alternately repeating the first period and the second period, wherein the at least one processor turns on all of the three switching elements at a crest of a carrier wave in the first period, and the at least one processor turns off all of the three switching elements at a crest of a carrier wave in the second period.

An air conditioner and a compressor protection circuit thereof are provided. When overcurrent occurs in a phase current of a compressor, an overcurrent level signal is output by a voltage comparison module, and is latched and output to an intelligent power module by a signal latching module, and the intelligent power module shuts off the output of the phase current according to the overcurrent level signal, so as to achieve the overcurrent protection of the compressor; and subsequently, a conventional level signal is output to the signal latching module by the voltage comparison module, the signal latching module keeps outputting the overcurrent level signal, and outputs the conventional level signal until a latching cancel signal output by a signal processing circuit is received, so that the intelligent power module starts the output of the phase current, thereby enabling the compressor to normally operate.

In one aspect, a refrigeration system is provided. The refrigeration system includes a compressor coupled to a variable frequency drive (VFD), a condenser, an evaporator, an oil separator, and an oil conditioning circuit. The oil conditioning circuit is thermally coupled to the VFD and configured to heat oil from the oil separator with heat produced by the VFD.