KR100358764B1 - inverter air conditioner control Method and apparatus - Google Patents

Abstract

The present invention relates to a control method and apparatus for an inverter air conditioner, and more particularly, to a control method and apparatus for an inverter air conditioner that can prevent damage to a circuit element due to a high DC voltage and bring about stable driving. will be. Therefore, the present invention detects the DC link voltage supplied to the power module of the compressor, and turns off the operation of the three-phase power switching module and the PFC control circuit operated for driving the compressor when the DC link voltage is low or high voltage.

Description

Inverter air conditioner control method and apparatus

The present invention relates to a control method and apparatus for an inverter air conditioner, and more particularly, to a control method and apparatus for an inverter air conditioner that can prevent damage to a circuit element due to a high DC voltage and bring about stable driving. will be.

An air conditioner is a device for maintaining indoor air in a state most suitable for use and purpose. For example, in summer, the room is cooled to a cool state, in winter, the room is heated to a warm state, and also the humidity of the room, and the air in the room to a comfortable clean state. As life convenience products such as air conditioners are gradually expanded and used, consumers are demanding high energy use efficiency, performance improvement and convenience products.

In addition, the increasing use of home appliances and electronic devices in homes, businesses, and factories has led many countries and organizations to regulate the use of their products in various ways. One example is international harmonic regulation, which limits the impact of harmonics on peripherals when a product is used.

However, the conventional inverter air conditioner has a problem that does not satisfy the international harmonic regulation.

Next, the problems of the conventional inverter air conditioner will be described in more detail with reference to FIG. 1.

The control circuit of the conventional inverter air conditioner, as shown in Figure 1, is provided with a communication control circuit unit 101 for performing communication with the indoor unit (not shown). The communication control circuit unit 101 receives a signal from a microcomputer (not shown) which controls each component of the outdoor unit as a whole and transmits the signal to the indoor unit. In addition, the communication control circuit unit 101 is responsible for inputting a signal transmitted from the indoor unit to the microcomputer in the outdoor unit.

The control circuit of the inverter air conditioner includes an EMI (spill noise) filter 103, an EMS (noise strength) filter 105 for removing noise of an AC voltage input, and a surge voltage included in the AC voltage input. It includes a surge up server 104 for removing. And a power relay 107 for forming a current path of the outdoor unit during normal operation of the air conditioner, and a PTC for preventing inrush current. In addition, a current transformer 109 for detecting the total current flowing to the outdoor unit, a four-way valve 111 for switching between cooling and heating, and a four-way relay 115 for controlling the operation of the four-way valve 111. ), And an outdoor fan 113 and a relay 117 for varying the speed of the outdoor fan.

In addition, the control circuit of the inverter air conditioner includes a rectifier circuit 119 for converting an input AC voltage into a DC voltage by a rectifier circuit composed of a bridge diode, and improving the power factor from the output voltage of the rectifier circuit 119. Reactive filter 121 and the capacitor 123 is configured for.

The passive filter stores energy in the reactor 121 and continues charging and discharging with the capacitor 123, and when there is a sudden change in the input current, the reactor 121 serves to compensate for the current, thereby harmonic distortion. Minimize the impact.

The voltage whose power factor is improved in the passive filter is applied to a DC voltage generator comprising capacitors C5 and C6. The DC voltage generator generates a DC voltage required for driving the outdoor unit. The DC voltage generated from the DC voltage generator is input to the IPM 129 which is a power module, and the IPM 129 generates a three-phase AC power for driving the compressor 125 from the input DC voltage.

Next, the outdoor unit control operation of the conventional inverter air conditioner having the above configuration will be described.

First, although not shown, the microcomputer receives an operation instruction from the microcomputer on the indoor unit side through the communication control circuit unit 101. That is, according to the cooling operation or the heating operation selected by the user, the microcomputer on the indoor unit gives an instruction for the operation of the cooling cycle or the heating cycle, and the instruction is sent to the microcomputer on the outdoor unit through the communication control circuit unit 101 of the outdoor unit. It becomes aware. Thereafter, the microcomputer controls the operation of the four-way valve 111 through the relay 115 according to the operation mode. The operation cycle of the air conditioner is controlled by the control operation of the four-way valve 111. In addition, the microcomputer controls the fan motor 113 through the relay 117 to rotate the fan.

Next, the AC power input to the outdoor unit through the external input terminal passes through the EMI filter 103 and the EMS filter 105, and a predetermined amount of noise component is removed from the filter.

The AC power supply via the filter is initially applied to the current transformer 109 after the inrush current is removed through the PTC resistor. After the compressor 125 of the outdoor unit is normally driven, the power relay 107 is turned on under the control of the microcomputer, and power is supplied to the current transformer 109 through the relay.

The current transformer 109 detects the input current and transmits the detected current value to the microcomputer to sense the total current value flowing to the outdoor unit.

AC power is supplied to the rectifier circuit 119 through one side of the current transformer 109, and the rectifier circuit 119 rectifies the input AC power into a DC voltage.

The DC voltage rectified by the rectifier circuit 119 is applied to a passive filter including a reactor 121 and a capacitor 123. The passive filter repeatedly performs an operation of charging and discharging the input current at predetermined time intervals, that is, the energy is stored in the reactor 121 and the charging and discharging operation is repeatedly performed by the capacitor 123. Therefore, when there is a sudden change in the input current, the reactor 121 serves to supplement the current to obtain a current waveform with a minimum of harmonic distortion. In addition, the phase of the input current and the voltage is adjusted by the accumulation time of energy accumulated by the reactor 121 and the discharge time of energy stored in the capacitor 123, and the charge / discharge time coincides with the harmonic components. When you get the maximum power factor improvement.

In this way, the harmonic distortion is reduced, and the voltage with improved power factor is applied to the DC voltage generation section composed of the capacitors C5 and C6. The capacitors C5 and C6 continue to charge the input voltage, and then discharge at a certain point to generate a DC voltage required for the outdoor unit.

The DC voltage generated in this way is applied to the IPM 129, and the IPM 129 generates a three-phase AC voltage which is the driving force of the compressor 125. That is, the conventional inverter air conditioner is the IPM ( A passive filter consisting of the reactor 121 and the capacitor 123 is used to improve the power factor according to the phase difference between the voltage and the current supplied to the power supply 129. However, the passive filter including the reactor 121 and the capacitor 123 is used. As described above, when the accumulation time of energy accumulated by the reactor 121 and the discharge time of energy accumulated in the capacitor 123 coincide with the harmonic components, a maximum power factor improvement effect can be obtained. . Therefore, when the charge and discharge time is inconsistent with the harmonic component, the power factor improvement effect is inevitably deteriorated. However, the charge / discharge time determined by the reactor 121 and the capacitor 123 may not be actively adjusted according to the harmonic components, but exists in a set state according to a preset value. The control circuit of the harmonic cannot actively cope with harmonic components, and the power factor is limited to about 85%. Therefore, the control circuit of the conventional inverter air conditioner includes a plurality of harmonics in the current waveform passing through the passive filter, which adversely affects external equipment. In view of this, the control circuit of the conventional inverter air conditioner has not satisfied the harmonic regulation standard due to the low power factor improvement. On the other hand, in order to solve the above-mentioned problem, in recent years, the manufacturing cost is satisfied while satisfying the international harmonic regulation standard. Inverter air conditioners employing a step-up PFC technology that can reduce and improve performance have been proposed. Inverter air conditioners employing the step-up PFC technology can actively cope with applied harmonic components. Therefore, the power factor improvement rate is very high. In addition, a high DC voltage is generated by a switching control method using an IGBT. However, an inverter air conditioner using a step-up PFC technology boosts a DC link voltage, thereby increasing the power supply of the IGBT switching element and power module of the PFC control circuit. IPM's IGBT switching device has a case where the withstand voltage is exceeded.

Accordingly, an object of the present invention is to provide a control method of an inverter air conditioner capable of preventing damage to an IGBT switching element due to a high DC voltage.

It is also an object of the present invention to provide a control method of an inverter air conditioner capable of suppressing an overcurrent flowing to an IGBT switching element due to an error of a PFC control circuit when a fluctuation range of an input voltage is large.

1 is a control block diagram of an inverter air conditioner according to the prior art,

2 is a control block diagram of an inverter air conditioner according to the present invention;

Figure 3 is a circuit diagram for the DC voltage detection of the present invention,

4 is a virtual diagram of the DC voltage change of the inverter air conditioner according to the present invention,

5 is a control flowchart of an inverter air conditioner according to the present invention;

6 is a control flow diagram connected to NEXT of FIG.

Explanation of symbols on the main parts of the drawings

11, 21: communication control unit 65: microcomputer

13 sensor detection unit 23 EMI filter

25: EMS filter 27, 35, 37: relay

29: current transformer 30: surge up west

31: 4-way valve 33: fan motor

41: rectifier circuit 43: choke coil

45: PFC control unit 47: IGBT switching device

49: diode 51: IPM

53: compressor

A control method of an inverter air conditioner according to the present invention for achieving the above object comprises: a first step of dividing an inputable DC link voltage into several voltage ranges and setting an operating state according thereto; Sensing a DC link voltage; A third operation of the compressor when the sensed DC link voltage is included in a range enabling normal operation of the compressor, and a third operation of stopping the operation of the compressor when the sensed DC link voltage is included in a low voltage or high voltage range in which normal operation is impossible. Steps; A fourth step of detecting whether the detected DC link voltage reaches a rated power supply of the compressor after a predetermined time from the start of the operation of the compressor; A fifth step of detecting whether the detected DC link voltage has fallen below the rated power of the compressor after a predetermined time from the end of the operation of the compressor; And a sixth step of determining as an error state when the condition of the fourth or fifth step is not satisfied.

A control device for an inverter air conditioner according to the present invention for achieving the above object comprises: a power factor improvement circuit switched to output an input current in accordance with an input voltage; Power factor improvement circuit control means for sensing an input voltage and an input current to adjust a switching time of the PFC control circuit; A three-phase power switching module for inputting a boosted DC link voltage based on the output voltage of the reverse current improving circuit and generating a three-phase AC power source; A compressor driven by the output of the three-phase power switching module; DC link voltage sensing means for sensing a DC link voltage input to the three-phase power switching module; A control means for dividing the input DC link voltage into several voltage ranges to set an operating state according thereto, and for controlling the operation of the power factor improving circuit and the three-phase power switching module based on the sensed DC link voltage. It is configured by.

Since the DC voltage of the inverter air conditioner can be boosted up to about 400 volts, the operation of the power switching device is turned off when the IGBT switching element of the PFC control circuit and the IGBT switching element of the IPM may be exceeded. It is characterized by preventing damage.

In addition, the present invention is characterized in that, when the input voltage is changed, overcurrent flows to the IGBT switching element from erroneous operation of the PFC control circuit, thereby protecting the power element.

Hereinafter, a method and apparatus for controlling an inverter air conditioner according to the present invention will be described in detail with reference to the accompanying drawings.

The control circuit of the air conditioner described later relates to an outdoor unit in an inverter air conditioner separated from an indoor unit composed of a heat exchanger and an outdoor unit composed of a compressor, a heat exchanger and the like.

2 is a control block diagram of an outdoor unit of the inverter air conditioner according to the present invention.

As shown in FIG. 2, the control circuit of the inverter air conditioner of the present invention is provided with a communication control circuit section 21 for performing communication with an indoor unit (not shown). The communication control circuit unit 21 receives a signal from the microcomputer 65 (shown in FIG. 3) which controls each component of the outdoor unit as a whole and transmits the signal to the indoor unit. The communication control circuit unit 21 plays a role of applying a signal transmitted from the indoor unit to the microcomputer in the outdoor unit.

In addition, the control circuit of the inverter air conditioner of the present invention is included in the EMI (spill noise) filter 23, the EMS (noise strength) filter 25, and the input AC voltage. And a surge up server 39 for removing the surge voltage. And a power relay 27 for turning on / off the power supply of the outdoor unit and a PTC for preventing inrush current. In addition, a current transformer 29 for detecting a current flowing in the outdoor unit, a four-way valve 31 for switching between cooling and heating, and a four-way relay 35 for controlling the operation of the four-way valve 31. And an outdoor fan 33 and a relay 37 for varying the speed of the outdoor fan.

In addition, the control circuit of the inverter air conditioner of the present invention is provided with an active filter which improves the power factor of 98%. The configuration is as follows.

An active filter for improving the power factor is connected to the rear end of the rectifier circuit 41 for converting an AC voltage input from the outside into a DC voltage, and the configuration thereof is the choke coil 43, the IGBT switching element 47, and the diode 49. And a sensing resistor Rs for current detection and a PFC controller 45 for controlling an on / off operation of the IGBT switching element 47.

In more detail, the choke coil 43 is connected to the first output terminal of the rectifier circuit 41, the sensing resistor Rs is connected to the second output terminal, and the current waveform detected by the sensing resistor Rs is PFC. It is input to the control part 45.

The capacitor C1 is connected between the first and second output terminals of the rectifier circuit 41, and to detect the voltage waveform output from the rectifier circuit 41, the first output terminal and the PFC of the rectifier circuit 41. Two resistors R1 and R2 are connected in series between the input terminals of the controller 45.

The other terminal of the choke coil 43 is connected to the anode terminal of the diode 49 and to the collector terminal of the IGBT switch 47. The gate terminal of the IGBT switch 47 is connected to the PFC controller 45 through a resistor R3, and the emitter terminal is connected to the ground potential. Another resistor R4 is connected between the resistor R3 and the gate terminal of the IGBT switch 47, and the resistor R4 is connected to the sensing resistor Rs. The PFC controller is connected to the cathode of the diode 49 to sense the DC link voltage.

That is, in the active filter of the present invention, energy is accumulated in the choke coil 43, and the accumulated energy is output while conducting the diode 49 as the IGBT switch element 47 is turned on and off. On / off control of the IGBT switch 47 is performed by the PFC controller 45, and the PFC controller 45 detects a voltage waveform from the output of the rectifier circuit 41, and controls the diode 49. Sensing the DC voltage at the output stage. The current waveform is sensed from the sensing resistor Rs to control the on / off time of the IGBT switch 47.

In this way, the voltage whose power factor is improved in the active filter is applied to the DC voltage generating unit composed of the capacitors C5 and C6. The DC voltage generator generates a DC voltage required for driving the outdoor unit. The DC voltage generated from the DC voltage generator is input to the IPM 51 which is a power module, and the IPM 51 generates a three-phase AC power for driving the compressor 53 from the input DC voltage. The resistor R5 connected to the IPM 51 is a resistor for sensing the total current flowing to the IPM.

The following briefly looks at the control operation of the inverter air conditioner according to the present invention having the above configuration.

The microcomputer 65 (shown in FIG. 3) receives an operation instruction from the microcomputer on the indoor unit side through the communication control circuit section 21. FIG. That is, according to the cooling operation or the heating operation selected by the user, the microcomputer on the indoor unit gives an instruction for the operation of the cooling cycle or the heating cycle, and the instruction is sent to the microcomputer on the outdoor unit through the communication control circuit unit 21 of the outdoor unit. 65).

Thereafter, the microcomputer 65 controls the operation of the four-way valve 31 through the relay 35 or the fan motor 33 through the relay 37 according to the operation mode. In addition, according to the operation command from the indoor unit, the PFC control unit 45 transmits a signal according to whether or not the PFC control circuit operates, and controls the output pulse width of the power module IPM.

After such a control operation, the AC power input to the outdoor unit through the external input terminal passes through the EMI filter 23 and the EMS filter 25, and a predetermined amount of noise components are removed from the filter.

The AC power supply via the filter is initially applied to the current transformer 29 after the inrush current is removed through the PTC resistor. After the compressor 53 of the outdoor unit is normally driven, the power relay 27 is turned on under the control of the microcomputer 65, and power is supplied to the current transformer 29 through the relay.

The current transformer 129 detects an input current and transmits the detected current value to the microcomputer 65 so as to sense the total current value flowing to the outdoor unit.

AC power is supplied to the rectifier circuit 41 through one side of the current transformer 29, and the rectifier circuit 41 rectifies the input AC power to a DC voltage. The full-wave rectified voltage in the rectifier circuit 41 is applied to the choke coil 43, and the choke coil 43 charges a current of several A until the IGBT switch 47 is turned on.

As mentioned above, after the operation signal is applied from the microcomputer 65, the PFC controller 45 detects the waveform of the full-wave rectified voltage in the rectifier circuit 41 through the resistors R1 and R2. . The current waveform is detected through the sensing resistor Rs. Recognizing the phase of the detected voltage waveform and the current waveform, the PFC controller 45 controls the on / off operation of the IGBT switch 47 so that the current can flow while following the sine wave of the input voltage.

That is, when a pulse width of several tens of KHz frequency is applied to the gate terminal of the IGBT switch 47 from the PFC control circuit 45 through the resistors R3 and R4, the IGBT switch 47 is turned off while the choke coil ( Current charged in 43 is charged to the DC voltage boosting capacitors C5 and C6 through the diode 49. When the IGBT switch 47 is turned on under the control of the PFC control circuit 45, the choke coil 43 again charges the current.

Accordingly, while the current charged in the choke coil 43 is repeatedly discharged in accordance with the off operation of the IGBT switch 47, power with an improved power factor of 98% or more is supplied to the boosting capacitor, The high DC voltage is output from the capacitors C5 and C6 and applied to the IPM 51. The IPM 51 converts the input DC voltage into a three-phase AC voltage again to control the drive voltage and frequency of the compressor 53.

At this time, the diode 49 in the active filter is for preventing reverse voltage to prevent the DC link voltage from flowing to the IGBT switching element.

In addition, when it is determined that the current sensed by the sensing resistor Rs is an overcurrent, a signal is applied from the microcomputer 65 to the IPM 51 on the basis of the signal output from the PFC controller 45, and thus the IGBT inside the IPM. The gate voltage of the switching element is controlled to be off. Therefore, the damage of the IGBT switching element due to overcurrent is prevented. In addition, the PFC controller 45 controls the gate voltage of the switching element inside the IPM 51 to be turned off even when the detected DC link voltage is excessively increased or has a low low voltage. This control operation is performed under the control of the microcomputer 65 on the basis of the signal transmitted from the PFC controller 45.

That is, the control circuit of the inverter air conditioner of the present invention improves the power factor by 98% or more by satisfying the charge / discharge operation of the PFC control circuit composed of the choke coil 43 and the IGBT switch 47 to satisfy the international harmonic regulation. The DC voltage is supplied to the IPM 51.

In addition, the control circuit of the inverter air conditioner of the present invention is stable DC regardless of the change in the input voltage by adjusting the on / off time of the IGBT switch 47 operated on / off under the control of the PFC controller 45. The voltage can be supplied to the DC boosting capacitors C5 and C6.

That is, the PFC controller 45 senses the DC link voltage applied to the output terminal of the diode 49 and adjusts the on time of the IGBT switching element 47 so that a constant DC link voltage can be supplied to the IPM module at all times. .

In addition, although the conventional inverter air conditioner is limited to a DC link voltage of up to 310 volts by the on / off control of the PFC controller 45 as described above, in the present invention according to the use of the PFC control circuit, the voltage boosted to 400 volts. This can be done.

Next, a description will be given of a portion in which the DC voltage is detected in the control circuit of the inverter air conditioner according to the present invention.

3 is a configuration diagram for detecting a boosted DC voltage in the control circuit of the inverter air conditioner of the present invention.

First, the DC link voltage input to FIG. 3 is applied from the output terminals of the DC voltage boosting capacitors C5 and C6 of FIG.

The DC link voltage input from the output terminal (shown in FIG. 2) of the DC voltage boost capacitors C5 and C6 is connected to the resistors R10 and R20 connected in series, and a diode and a capacitor connected between the voltage of DC 5 volts and the ground potential. C10), and is input to the input terminal AD1 of the microcomputer 65 through the resistor R30.

The microcomputer 65 inputs a DC link voltage of an analog component through the resistor and the capacitor, and converts the input analog signal into a digital signal using an internal analog / digital converter (not shown) to convert the DC link voltage. Is detected.

According to the detected DC link voltage, the microcomputer 65 outputs the on / off control signal of the PFC controller 45 through the output terminal OUT1, and simultaneously U, V, W, and the like to the IPM control circuit which is a power module. Control pulse widths of X, Y, and Z respectively.

That is, as shown in Fig. 4, the DC link voltage flowing in the control circuit of the inverter air conditioner can be changed in various situations according to the input voltage.

When the input voltage suddenly drops as shown in part a of FIG. 4, the PFC controller 45 takes the on time of the IGBT switching device above a threshold value to compensate for the low voltage. This will cause damage to the device. In addition, when the load of the compressor is changed to a light load, a high DC voltage as shown in part e of FIG. 4 stays in the IGBT switching element in the IPM, and in this case also causes breakage of the IGBT switching element in the IPM.

In addition, when a malfunction of the PFC control circuit occurs in the operating state of the compressor, a case in which the voltage drops rapidly as shown in part f of FIG. 4.

Therefore, when the DC voltage is unstable, it is necessary to control the operation of the IPM and PFC control circuits to prevent breakage of the power switching element.

5 is an operation flowchart for controlling the inverter air conditioner according to the present invention. 6 is a control flowchart connected to the NEXT of FIG. 5.

The microcomputer 65 (shown in FIG. 3) receives an operation instruction from the microcomputer on the indoor unit side through the communication control circuit section 21. FIG. That is, according to the cooling operation or the heating operation selected by the user, the microcomputer on the indoor unit gives an instruction for the operation of the cooling cycle or the heating cycle, and the instruction is sent to the microcomputer on the outdoor unit through the communication control circuit unit 21 of the outdoor unit. 65).

Therefore, the microcomputer 65 controls the operation of the four-way valve 31 through the relay 35 or the fan motor 33 through the relay 37 according to the operation command received from the indoor unit.

Further, the microcomputer 65 sets a control flag for driving the compressor in accordance with the operation command received from the indoor unit. If the indoor unit is instructed to drive the compressor, the control flag of the compressor is set. If the compressor is not instructed, the control flag of the compressor is not set. For example, when the user inputs a key according to the operation of the air conditioner, the microcomputer on the indoor unit side which inputs the key instructs the microcomputer of the outdoor unit to drive the compressor, and thus the microcomputer of the outdoor unit The operation is started by setting the control flag of.

Therefore, in step 200, when the control flag state of the compressor is determined, and when the control flag of the compressor is not set, the microcomputer 65 determines that it is not necessary to perform a control operation for generating driving power of the compressor, The control unit 45 is controlled to be in an off state to stop the operation, and at the same time, the U, V, W, X, Y and Z signals applied to the IPM control circuit are turned off. Then, the value of the PFC operation timer for checking the time for the operation of the PFC control circuit is cleared (step 203).

However, if the control flag of the compressor is set in step 200, the microcomputer 65 recognizes that the driving of the compressor should be performed, and performs the control operation for generating the driving power accordingly.

First, when the drive frequency of the compressor is 15 Hz or less (step 206), the microcomputer 65 determines that the operation state of the compressor is almost stopped. Therefore, the microcomputer 65 controls the off state for stopping the operation of the PFC control section 45 and turns off the U, V, W, X, Y, and Z signals applied to the IPM control circuit. Then, the value of the PFC operation timer for checking the time for the operation of the PFC control circuit is cleared (step 203).

When the driving frequency of the compressor is greater than or equal to 15 Hz in step 206, the DC link voltage flowing to the output terminal of the DC voltage boosting capacitors C5 and C6 of the outdoor unit is detected through the DC link voltage sensing circuit shown in FIG. .

At this time, if the detected DC link voltage is detected to be 160 volts or less (step 209), it is determined as a momentary power failure or the like, and controlled to the off state to stop the operation of the PFC controller 45, and applied to the IPM control circuit. Turns off the U, V, W, X, Y, and Z signals. Then, the PFC on flag indicating the operation state of the PFC control circuit is cleared (step 221).

Next, the DC voltage flowing to the output terminal of the DC voltage boosting capacitors C5 and C6 of the outdoor unit through the DC link voltage sensing circuit shown in FIG. 3 is 350 volts or less (step 212), and the DC voltage is 450 volts or less. Is included (step 215), the microcomputer 65 outputs the PFC ON signal to the output terminal OUT1 for starting the operation of the PFC control circuit. At this time, the PFC ON flag is set (step 218).

Subsequently, the microcomputer 65 continuously detects the DC link voltage through the DC link voltage sensing circuit, unless the control command according to the driving stop of the compressor is applied from the indoor unit, and the detected voltage is determined in steps 212 and 212. When the condition of step 215 is satisfied, the driving voltage of the compressor is generated by controlling the PFC control circuit and the IPM so that the normal driving of the compressor can be performed.

That is, the process of c, d part in FIG. 4 is a section in which the normal driving of the compressor is driven by the PFC control circuit and the IPM.

However, when the DC link voltage detected through the DC link voltage sensing circuit falls below 160 volts (step 209), or when the drive frequency of the compressor is controlled to 15 Hz or less, the microcomputer 65 of the PFC controller 45 While controlling the operation to the OFF state, the U, V, W, X, Y, and Z signals applied to the IPM control circuit are turned off (steps 203 and 221).

That is, when the DC voltage to be detected, such as low voltage or momentary power failure, is irregular even when the compressor is continuously driven, step 203 is performed to suppress damage of the IGBT switching elements of the PFC control circuit and the IPM control circuit due to excessive driving. And step 221.

In addition, in step 215, as shown in part e of FIG. 4, even when the DC link voltage is rapidly increased, step 221 may be performed to prevent damage to the power device due to the high DC link voltage occurring in the IGBT switching device. prevent.

Next, when the driving of the compressor is performed while the control command according to the driving stop of the compressor is not applied from the indoor unit, when the DC link voltage detected through the DC link voltage sensing circuit is included within 350 volts (step 224). The microcomputer 65 first checks the PFC operation flag state to determine whether the PFC control circuit is in the operating state (step 300).

If the PFC operation flag is in the set state in step 300, the operation time of the PFC operation timer is checked to determine whether the DC link voltage is included in 350 volts or less after a predetermined time (about 2 seconds) has elapsed. Step 309), the control of the PFC control unit 45 to the off state to stop, and at the same time, the U, V, W, X, Y, Z signal applied to the IPM control circuit is turned off. Then, the value of the PFC operation timer for checking the operation time of the PFC control circuit is cleared (step 306).

When the PFC operation flag is not in the set state in step 300, when the time of the PFC operation timer is checked and the DC link voltage continues to be included at 350 volts or less even after a predetermined time (about 2 seconds) has elapsed ( Step 303), while controlling to the off state to stop the operation of the PFC control unit 45, the U, V, W, X, Y, Z signal applied to the IPM control circuit is turned off. Then, the value of the PFC operation timer for checking the operation time of the PFC control circuit is cleared (step 306).

That is, in step 309, after the PFC control circuit is turned on, it is determined whether the DC link voltage rises 350 volts after a predetermined time. In step 303, after the PFC control circuit performs normal operation and turned off, To determine if the DC link voltage drops below 350 volts after time. Therefore, when the steps 303 and 309 are not satisfied, it is determined that an error occurs in the PFC control circuit and the operation of the IPM and PFC control circuits is turned off immediately.

That is, the control method of the inverter air conditioner according to the present invention monitors the DC link voltage input to the IPM module, and when the monitored voltage is too low or high voltage, turns off the operation of the IPM module so that the three-phase in the IPM module is turned off. The breakage of the power switching element is suppressed.

As described above, the present invention further expands the operation range of the compressor by boosting the DC voltage in the air conditioner using the PFC circuit. When the voltage resistance of the power switching device may be exceeded due to the boosted voltage, the operation of the power switching device may be turned off to induce driving of a stable air conditioner while protecting the circuit device.

Claims (2)

A power factor improvement circuit that is switched to follow the input voltage and output an input current; Power factor improvement circuit control means for sensing an input voltage and an input current to adjust a switching time of the power factor improvement circuit; A three-phase power switching module for inputting a boosted DC link voltage based on the output voltage of the reverse current improving circuit and generating a three-phase AC power source; A compressor driven by the output of the three-phase power switching module; DC link voltage sensing means for sensing a DC link voltage input to the three-phase power switching module; A control means for dividing the input DC link voltage into several voltage ranges to set an operating state according thereto, and for controlling the operation of the power factor improving circuit and the three-phase power switching module based on the sensed DC link voltage. Control circuit of the inverter air conditioner configured by. Dividing the input DC link voltage into several voltage ranges and setting an operating state according thereto; Sensing a DC link voltage; A third operation of the compressor when the sensed DC link voltage is included in a range enabling normal operation of the compressor, and a third operation of stopping the operation of the compressor when the sensed DC link voltage is included in a low voltage or high voltage range in which normal operation is impossible. Steps; A fourth step of detecting whether the detected DC link voltage reaches a rated power supply of the compressor after a predetermined time from the start of the operation of the compressor; A fifth step of detecting whether the detected DC link voltage has fallen below the rated power of the compressor after a predetermined time from the end of the operation of the compressor; And a sixth step of determining as an error state when the condition of the fourth or fifth step is not satisfied.