JP4164554B2 - Refrigeration apparatus and inverter apparatus used therefor - Google Patents

Description

  The present invention relates to a refrigerating apparatus such as an air conditioner or a refrigerator equipped with a compressor having a built-in electric motor capable of changing the number of revolutions, and an inverter apparatus used therefor.

  Conventionally, in a refrigeration system and an inverter device used therefor, in order to reduce the size and improve the reliability, an active converter that converts an AC voltage from an AC power source into a DC using an active element, and converts the generated DC into an AC A first board on which an inverter for driving an electric motor built in the compressor is mounted, a microcomputer for controlling the active converter and the inverter, a second board on which a current detection mechanism is mounted, and various temperatures of the refrigeration cycle Or it is known to arrange | position to the 3rd board | substrate which mounts the interface circuit to which the detection signal of a pressure is input, and is described in patent document 1, for example.

JP 2004-53050 A

  In the above prior art, the case where an overcurrent flows to the active converter is not taken into account, and an instantaneous power failure of the power source occurs and the DC voltage decreases while the motor is operating by driving the active converter and the inverter. In such a case, there is a risk that the power supply current will rise and become overcurrent in order to secure the power supplied to the motor.

  Also, when the DC voltage drops, the microcomputer works to return to the control target value, so the power supply current tends to increase, and the power supply current exceeds the overcurrent set value provided for protection of the active converter. In the case of failure, the drive of the inverter is stopped and the operation of the motor is stopped. Therefore, the comfort as a refrigeration apparatus may be impaired.

  In addition, when the motor is operated under low power supply voltage and overload conditions, excessive power supply current continues to flow through the active converter, causing excessive stress on the power semiconductor of the active converter and damaging the power semiconductor. , Reliability may be impaired.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and in an active converter mounted on a refrigeration apparatus such as an air conditioner or a refrigerator and an inverter device used therefor, when an excessive power supply current flows due to an instantaneous power failure Or, even when an excessive power supply current flows in an overload state, the comfort of the refrigeration apparatus is ensured and the reliability is improved.

In order to achieve the above object, the present invention has a refrigeration cycle provided with a compressor, the compressor is driven by an electric motor whose operating frequency is variably controlled, and an active element is used to generate direct current from an alternating voltage. In a refrigeration apparatus comprising: an active converter to be generated; a smoothing capacitor connected to an output of the active converter; and an inverter that converts the generated direct current into alternating current to drive the electric motor with a variable operating frequency. A power supply current detection circuit for detecting a power supply current flowing in the active converter, a DC current detection circuit for detecting a DC current flowing in the inverter, a DC voltage detection circuit for detecting a DC voltage generated by the active converter, A microcomputer that outputs and controls a switching command to the active converter and the inverter When the upper control board for controlling the freezing cycle, the interface for communicating microcomputer and said upper control board - a for face connector, the microcomputer, detected by the power supply current detection circuit When the generated power supply current becomes the overcurrent set value 1, the switching command output to the inverter is continued, the switching command output to the active converter is stopped , and the switching command output to the active converter is stopped. During this time, an active converter stop signal is transmitted to the host control board via the interface connector .

The present invention also provides an active converter that variably controls the operating frequency of an electric motor that drives a compressor of a refrigeration cycle and generates direct current from an alternating voltage using an active element, and a smoothing capacitor connected to the output of the active converter And an inverter that converts the generated direct current into alternating current to drive the motor by changing an operating frequency thereof, and an inverter device comprising: a power supply current detection circuit that detects a power supply current flowing through the active converter; A direct current detection circuit for detecting a direct current flowing through the inverter, a direct current voltage detection circuit for detecting a direct current voltage generated by the active converter, and a microcomputer for outputting and controlling a switching command to the active converter and the inverter When the upper control board for controlling the freezing cycle The microcomputer and the upper control board and interface for communication - a connector face, the microcomputer, if the detected power supply current by the power supply current detection circuit becomes an overcurrent set value 1 The switching command output to the inverter is continued, the switching command output to the active converter is stopped , and the switching command output to the active converter is stopped, while the active converter stop signal is sent to the host control board The data is transmitted via the interface connector .

  According to the present invention, when an electric motor is operated by an active converter and an inverter, even if an excessive power supply current flows due to an instantaneous power failure or an excessive power supply current flows in an overload state, Since the active converter is temporarily stopped without stopping the operation, the comfort as the refrigeration apparatus can be maintained and the reliability can be improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a refrigeration cycle system diagram of a refrigeration apparatus according to an embodiment, in which a compressor 101, an indoor heat exchanger 102, an indoor expansion valve 104, an outdoor heat exchanger 105, and an accumulator 107 are sequentially connected. The refrigerant is circulated to form a refrigeration cycle. When the room is cooled, the refrigerant compressed by the compressor 101 is condensed and liquefied by the outdoor heat exchanger 105, then decompressed by the indoor expansion valve 104, evaporated by the indoor heat exchanger 102, and compressed by the compressor 101. Return to. The indoor fan motor 103 promotes heat exchange of the indoor unit 109, and the outdoor fan motor 106 promotes heat exchange of the outdoor unit 108.

The compressor 101 is driven by an electric motor 111 whose operation frequency is variably controlled in relation to the capacity required for the refrigeration cycle, and the operation frequency is controlled by an inverter device 210.
The refrigeration cycle includes the opening of an indoor expansion valve 104 or an outdoor expansion valve (not shown) for adjusting the refrigerant flow rate in addition to the rotation speed of the compressor 101, the rotation speed of the indoor fan motor 103 and the outdoor fan motor 106, A four-way valve (not shown) that switches between the cooling / heating operation modes is controlled. As information for this, the operation command signal from the remote control for setting the operation mode, temperature, etc., the temperature of each part (the discharge gas temperature of the compressor, the outside air) Temperature, heat exchanger temperature, evaporation temperature, suction temperature, blow-out temperature, freezing temperature, gas pipe temperature, etc.) and signals (pressure detected by the compressor, discharge pressure), etc. are input to the cycle control board 250. .
Further, the inverter required frequency output from the cycle control board 250 is input via the interface connector 240, and the operating frequency and the motor operating current are output from the inverter device 210 to the cycle control board 250. .

  The detection signal and the command signal input to the cycle control board 250 are input to the microcomputer 231 via the interface connector 240, whereby the refrigeration cycle control is performed by the inverter device 210. Various control mechanisms (outdoor expansion valve, outdoor fan motor 106, four-way valve for switching between cooling / heating operation modes) are controlled.

  FIG. 2 is a block diagram of an inverter device, and an active converter 225 that converts an AC voltage from a single-phase AC power source 251 into DC using an active element, and a motor 111 that converts the generated DC into AC. An inverter 221 to be driven, a power supply current detection circuit 236 having a shunt resistor 225 for detecting a power supply current flowing through the active converter 225, a DC current detection circuit 233 having a shunt resistor 224 for detecting a DC current flowing through the inverter 221; DC voltage detection circuit 238 for detecting the DC voltage generated by converter 225, microcomputer 231 for controlling active converter 225 and inverter 221, inverter driver circuit 232 for switching the inverter power semiconductor, and active converter Half power Active converter driver circuit 235 for switching the body, overcurrent detection circuit 237 for detecting an excessive power supply current flowing through active converter 225, communication circuit 239 for communicating with cycle control board 250, microcomputer 231 and inverter Current detection circuit 233, active converter current detection circuit 236, inverter driver circuit 232, active converter driver circuit 235, active converter overcurrent detection circuit 236, and power supply circuit 234 for supplying control power to communication circuit 239; And an inverter control board 230 on which is mounted.

  The AC voltage from the single-phase AC power source 251 is composed of an active converter 225 (a circuit in which a plurality of rectifier elements 229 are bridge-connected, and a step-up chopper circuit provided with a switching element 226 and a fast recovery diode 227 to improve the power source power factor. The inverter 221 (power conversion means in which the switching element 222 is connected in a three-phase bridge) that is a DC / AC converter is controlled as an AC frequency by the microcomputer 231. The electric motor 111 is driven.

  In the active converter 225, the AC voltage is rectified by a plurality of rectifier elements 229, an electromagnetic contactor 253 that operates or stops the electric motor 111 built in the compressor 101, a power factor improving reactor 252, a switching element 226, -Streakage-reaches the smoothing capacitor 270 via the element 227.

  Further, an inrush current limiting resistor 254 is provided in parallel with the electromagnetic contactor 253 so that the electromagnetic contactor 253 that is closed when the power is turned on does not weld due to an excessive inrush current flowing through the smoothing capacitor 270.

In inverter 221, flywheel element 223 is provided alongside switching element 222 in order to regenerate back electromotive force generated by switching element 222 during switching.
The current supplied to the electric motor 111 is detected by the inverter shunt resistor 224 as a direct current flowing through the inverter power semiconductor, amplified by the current detection circuit 233 and taken into the microcomputer 231. The sine wave alternating current output to the motor is reproduced and monitored at.
The current input from the single-phase AC power supply 251 is detected by the active converter shunt resistor 228, amplified by the active converter current detection circuit 236, and taken into the microcomputer 231. Monitored by the microcomputer 231.
Further, the current input from the single-phase AC power source 251 is detected as a DC current by the active converter shunt resistor 228, the overcurrent is determined by the active converter overcurrent detection circuit 237, and the microcomputer 231 Be monitored.

  Between the microcomputer 231 and the switching element 222, an inverter driver circuit 232 is provided that amplifies the switching element 221 to a level at which the switching element 221 can be driven by a weak signal from the microcomputer 231. Further, an active converter driver circuit 235 is provided between the microcomputer 231 and the active switching element 226 to amplify the switching element 226 to a level at which the switching element 226 can be driven by a weak signal from the microcomputer 231.

The communication circuit 239 includes an interface connector 240 to which a signal from the cycle control board 250 is input, and a photocoupler 241 that transmits the input signal to the microcomputer 231 by an optical signal, and electrical isolation is obtained. Send and receive in state.
A part of the direct current generated by the active converter 225 is adjusted from a high voltage to a control power source such as 5V or 15V by the power supply circuit 234, and the microcomputer 231 and the inverter current detection circuit 233, the active converter current detection circuit 236, The inverter driver circuit 232, the active converter driver circuit 235, the active converter overcurrent detection circuit 237, the voltage detection circuit 238, and the communication circuit 241 are supplied.

FIG. 3 is a time chart (1) relating to control, and shows the flow of control and phenomenon when an instantaneous power failure occurs when the electric motor 111 is operating by driving the active converter 225 and the inverter 221. .
When an instantaneous power failure occurs (from point A to point D in the figure), the DC voltage drops, but the power supply current tends to rise to ensure the power supplied to the motor. However, since the motor current is controlled by the inverter 221, the current does not change without depending on the decrease in the DC voltage.
Then, as the DC voltage decreases, the output to the active converter 225 is varied to increase the voltage from the time (B point) when the microcomputer 231 determines to increase the voltage to the control target voltage. On the other hand, the power supply current rises to raise the DC voltage.
When the instantaneous power source current recognized by the microcomputer 231 reaches or exceeds the overcurrent set value 1 provided in the microcomputer 231 (C point), the drive output of the active converter 225 is stopped. The electric motor continuously outputs the drive signal of the inverter 221 in order to continue the operation. When the active converter 225 is stopped, the DC voltage decreases and the power supply current also decreases.

From the point D where the instantaneous power failure is restored, the inverter is operated in the same manner as an inverter device not equipped with the active converter 225.
When the microcomputer 231 determines that the active converter 225 is driven (when the average power supply current recognized by the microcomputer 231 exceeds the set current), the drive output of the active converter 225 is performed. By re-driving, the DC voltage (control target voltage) before the instantaneous power failure is restored at point F.

By performing the above control, the operation of the electric motor 111 is continued without stopping the inverter 221 even if an instantaneous power failure occurs, thereby ensuring the comfort of the refrigeration apparatus such as an air conditioner or a refrigerator. Can do. And the power supply current which flows into the active converter 225 is detected, and when the overcurrent set value 1 provided in the microcomputer 231 is exceeded, the active converter 225 is stopped, thereby ensuring the reliability of the active converter. .
Note that while the active converter 225 is stopped, the power supply current rises as compared to when it is originally driven, so there is a concern about the reliability of the fast recovery diode 227. It is sufficient that the driving condition of 225 is always satisfied,
Even when the active converter 225 is stopped, the time is short (the time according to the processing timing of the microcomputer 231 and the soft drive of the active converter 225 (the drive system in which the DC voltage is gradually increased so that the power supply current does not jump up when the active converter is driven)). It is possible to maintain the reliability without causing any trouble in actual use than re-driving in the accompanying time).

Further, the active converter 225 is driven by using the overcurrent signal output from the overcurrent detection circuit 237 for the active converter instead of the overcurrent set value 1 provided in the microcomputer 231 for the overcurrent determination of the power supply current. It is also good to stop.
Furthermore, when restarting the drive of the active converter 225, the control can be simplified by restarting the drive after a predetermined time instead of determining that the drive condition is satisfied.

  Furthermore, while the active converter 225 is stopped, the inverter operating frequency is lowered to a predetermined frequency, so that the power source current can be reduced, and the burden on the fast recovery diode 227 is reduced, so that the reliability is further improved. Can be improved.

  Further, by transmitting an active converter stop signal to the cycle control board 250 while the active converter 225 is stopped, the control state in the inverter device 210 can be grasped by the cycle control board, and control by the refrigeration cycle components It is preferable to reduce the power supply current by (variable blower rotation speed, variable expansion valve opening, etc.).

FIG. 4 is a time chart (2) showing the flow of control and phenomenon when the overload state continues for a predetermined time in the case where the motor 111 is operated by driving the active converter 225 and the inverter 221.
When an overload condition occurs (point a), the current of the motor 111 increases, and the power supply current increases accordingly.
From the time point (b point) when the average power supply current recognized by the microcomputer 231 exceeds the overcurrent set value 2 (smaller than the overcurrent set value 1) provided in the microcomputer 231 until a predetermined time has passed (c point) When an excessive power supply current continues to flow, the microcomputer 231 lowers the inverter operating frequency to a predetermined frequency (point d), thereby reducing the power supply current. Then, the operation of the electric motor 111 is continued. Therefore, the comfort of refrigeration apparatuses such as air conditioners and refrigerators can be maintained.

FIG. 5 shows a module configuration of the inverter device, which includes a case 262 that covers the side surface of the power element mounting substrate 220 and is provided with a power input terminal block 260 and a motor output terminal block 261, from the bottom surface of the case 262. The power element mounting board 220 and the inverter control board 230 are arranged in a hierarchy in order.
The power element mounting board 220 includes a switching element 226 and a fast recovery diode 227, a rectifier element 229, a shunt resistor, an inverter functional part, a switching element 222, a flywheel element 223, and a shunt resistor.
The inverter control board 230 includes a microcomputer 231, an inverter driver circuit 232, an inverter current detection circuit 233, a voltage detection circuit 234, an active converter driver circuit 235, an active converter current detection circuit 236, and an active overcurrent detection circuit. 237, a power supply circuit 238, an interface connector 240, and a photocoupler 241.

In addition, heat dissipating fins 265 that dissipate heat from both the active converter 225 and the inverter 221 are in close contact with the non-mounting surface of the power element mounting substrate 220.
The power element mounting board 220 and the inverter control board 230 are connected by lead pins 264, and a case cover 263 is attached to the upper surface of the case 262. That is, the inverter control board 230 is configured on the case cover 263, and the outer shape of the inverter control board 230 is made smaller than the case 262 outer shape. Therefore, useless space can be eliminated even when the inverter device is mounted on, for example, an outdoor unit of an air conditioner.

In addition, since the power element mounting substrate 220 and the inverter control substrate 230 are compactly arranged close to each other in a hierarchical manner, the wiring length in a portion where noise is likely to be generated can be shortened, so that the cause of noise generation can be reduced.
Further, a relatively weak communication signal having a large influence of electromagnetic noise, for example, a large influence from the compressor 101 that requires a large current, is transmitted to the microcomputer 231 by an optical signal via the photocoupler 243. Therefore, it is possible to improve the reliability of the refrigeration cycle by eliminating malfunction due to noise.

The refrigeration cycle figure of the air conditioner by one embodiment of this invention. The block diagram of the inverter apparatus by one embodiment of this invention. The time chart (1) which concerns on control by one embodiment of this invention. The time chart (2) which concerns on control by one embodiment of this invention. The perspective view which shows the module structure of the inverter apparatus by one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Compressor, 102 ... Indoor heat exchanger, 103 ... Indoor fan motor, 104 ... Indoor expansion valve, 105 ... Outdoor heat exchanger, 106 ... Outdoor fan motor, 107 ... Accumulator, 108 ... Outdoor unit, 109 ... Indoor unit, 110 ... Air conditioner, 111 ... Compressor motor, 210 ... Inverter device, 220 ... Power element mounting board, 221 ... Inverter, 222 ... Switching element for inverter, 223 ... Fly wheel element, 224 ... For inverter Shunt resistor, 225 ... Active converter, 226 ... Switching element for active converter, 227 ... Fast recovery diode, 228 ... Shunt resistor for active converter, 229 ... Rectifier, 230 ... Inverter control board, 231 ... Microcomputer (microcomputer) ), 232 ... Inverter driver circuit, 233 ... Inverter current detection circuit, 234 ... Voltage detection circuit, 235 ... Active converter Driver circuit, 236 ... Active converter current detection circuit, 237 ... Active overcurrent detection circuit, 238 ... Power supply circuit, 239 ... Communication circuit, 240 ... Interface connector, 241 ... Photocoupler, 250 ... Cycle control board, 251 ... Single-phase AC power supply, 252 ... Reactor, 253 ... Electromagnetic contactor, 254 ... Current limiting resistor, 255 ... Cycle control board, 260 ... Power input terminal block, 261 ... Motor output terminal block, 262 ... Case, 263 ... case cover, 264 ... lead pin, 265 ... radiation fin.

Claims (2)

An refrigeration cycle having a compressor, wherein the compressor is driven by an electric motor whose operating frequency is variably controlled, and an active converter that generates direct current from an alternating voltage using an active element, and is connected to an output of the active converter In a refrigeration apparatus comprising: a smoothing capacitor that is generated; and an inverter that converts the generated direct current into alternating current to drive the electric motor with a variable operating frequency.
A power supply current detection circuit for detecting a power supply current flowing through the active converter;
A direct current detection circuit for detecting a direct current flowing in the inverter;
A DC voltage detection circuit for detecting a DC voltage generated by the active converter;
A microcomputer that outputs and controls a switching command to the active converter and the inverter;
A host control board for controlling the refrigeration cycle;
An interface connector for performing communication between the microcomputer and the host control board;
When the power supply current detected by the power supply current detection circuit becomes an overcurrent set value 1 , the microcomputer continues the switching command output to the inverter, stops the switching command output to the active converter , While the switching command output to the active converter is stopped, an active converter stop signal is transmitted to the host control board via the interface connector . An active converter that variably controls the operating frequency of an electric motor that drives a compressor of a refrigeration cycle, generates direct current from an alternating voltage using an active element, a smoothing capacitor connected to the output of the active converter, and the generated direct current Inverter device comprising: an inverter that converts AC to AC and varies the driving frequency of the electric motor to drive.
A power supply current detection circuit for detecting a power supply current flowing through the active converter;
A direct current detection circuit for detecting a direct current flowing in the inverter;
A DC voltage detection circuit for detecting a DC voltage generated by the active converter;
A microcomputer that outputs and controls a switching command to the active converter and the inverter;
A host control board for controlling the refrigeration cycle;
An interface connector for performing communication between the microcomputer and the host control board;
When the power supply current detected by the power supply current detection circuit becomes an overcurrent set value 1 , the microcomputer continues the switching command output to the inverter, stops the switching command output to the active converter , An inverter device characterized by transmitting an active converter stop signal to the host control board via the interface connector while the switching command output to the active converter is stopped .

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