KR20070030073A - Driving device of inverter air-conditioner and its control method - Google Patents

Abstract

A device for driving an inverter air conditioner and a control method thereof are provided to sense an over-current at a line current terminal of a compressor to increase precision in compressor control and to increase a pulse width of an inverter for boosting a voltage applied to a compressor motor, thereby realizing stable operation of a compressor in overload situation. A device for driving an inverter air conditioner includes a switching part(40) for driving one or more switching elements by DC power to generate high output current. A line current sensing part(50) senses line current flowing through a predetermined line current terminal from the switching part to a compressor motor(M). A control part(60) compares the sensed current with a reference one to determined an over-current state, and outputs a control signal for increasing a pulse width in the over-current state. A pulse width varying part(70) varies a width of a driving pulse applied to the compressor motor according to the control signal output from the control part.

Description

Driving device of inverter air conditioner and its control method {Driving device of inverter air-conditioner and its control method}

1 is a block diagram of a driving device of a conventional inverter air conditioner,

2 is a block diagram of an inverter air conditioner driving apparatus of the present invention;

3 is a graph showing the relationship between the line-to-line voltage of the present invention,

4 is a graph showing the width of a normal driving pulse;

5 is a graph showing the width of the driving pulse at the time of overcurrent detection;

6 is a flowchart illustrating a method of driving an inverter air conditioner according to the present invention.

<Explanation of symbols on main parts of the drawings>

10: power stage 20: rectifier

30: filter unit 40: switching unit

50: compressor line current detection unit 60: control unit

70: pulse width variable part

The present invention relates to a drive device for an inverter air conditioner and a control method thereof, and in particular, detects a phase current value flowing through a compressor, and increases the voltage applied to the compressor motor by increasing the pulse width when the reference value is exceeded, thereby stably under overload conditions. A drive device for an inverter air conditioner capable of driving a compressor and a control method thereof.

In general, a device that converts electrical alternating current into direct current or reversely converts direct current into alternating current is called an inverter, and an air conditioner that drives a compressor by applying this is called an inverter air conditioner.

As described above, the inverter air conditioner converts a constant AC voltage through rectification and then converts it into AC again, thereby changing the frequency of refrigerant according to cooling or heating load conditions. As the rotation speed of the motor is changed according to the change, cooling or heating loads can be eliminated, thereby enabling low power consumption and low power operation.

In the inverter air conditioner, when the difference between the indoor temperature and the outdoor temperature changes suddenly, the compressor pressure increases due to overload, and when the current applied to the compressor rapidly rises to reach the peak current value, the compressor operating frequency is decreased or operated by the controller 6. Since the system is protected by the stop, the drive device of the conventional inverter air conditioner is a power supply line current detection unit 5 for detecting the line current flowing through the power supply terminal as shown in Figure 1 and the compressor to change the operating frequency of the compressor The frequency variable part 7 is comprised and comprised.

In addition, when the current sensed by the power supply line current detection unit 5 flows above the reference value, the control unit 6 which applies a control signal to the compressor frequency variable unit 7 so that the operation frequency of the compressor is controlled downward. It is configured to include.

That is, in the drive device of the conventional inverter air conditioner, the line current flowing into the compressor is not sensed, but the total current applied to the drive device as a whole is connected to the power supply line 1. Since the detection, there was a problem that the control of the compressor due to the overcurrent is incorrect.

The present invention has been made to solve the above problems of the prior art, the object of the present invention is to increase the accuracy of the compressor control by detecting overcurrent in the line current stage of the compressor, and if the overcurrent is detected by increasing the pulse width of the inverter motor The present invention provides a drive device and a method of driving the inverter air conditioner to increase the voltage applied to enable a stable operation of the compressor even under overload conditions.

The drive device of the inverter air conditioner according to the present invention for solving the above problems is a switching unit for generating a high output current by driving one or more switching elements using a DC power supply, a predetermined predetermined applied to the compressor motor from the switching unit Compressor line current detection unit for detecting the current flowing in the line current stage and the current detected by the compressor line current detection unit compares the reference value to determine the overcurrent state, and in the case of the overcurrent state control to increase the pulse width And a pulse width variable portion for varying a width of a driving pulse applied to the compressor motor according to the control signal of the controller.

In addition, the driving method of the inverter air conditioner according to the present invention is to determine the overload / normal load state by comparing the first step of detecting the line current applied to the compressor motor and whether the detected current value exceeds the reference value for overload determination A second step, and a third step of generating a driving pulse in which the pulse width, which is a high section, is increased in an overload state, and generating a driving pulse by maintaining a predetermined pulse width in a normal load state, and a pulse width in a third step. And a fourth step in which the compressor motor is driven by the controlled drive pulses.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a configuration diagram of a drive device for an inverter air conditioner of the present invention, and the configuration of the present invention will be described in detail with reference to the drawing.

An inverter circuit is a circuit that converts an alternating current input to the power supply terminal 10 into a direct current, and generates a high frequency high output current by switching control using a direct current. An apparatus for driving a device connected to an output terminal using such a circuit is an inverter. It is called a driving device.

In the air conditioner to which the inverter circuit is applied, the high frequency high output current generated by the inverter circuit is applied to the compressor motor M to control the rotation of the compressor. As a result, the amount of refrigerant circulated to the outdoor unit and the indoor unit is controlled to control the cooling load or the heating. The load is released.

The driving device of the inverter air conditioner basically includes a power stage 10 to which AC power (for example, three-phase power of R / S / T) is supplied, and a rectifier 20 to rectify the AC power through a rectifier diode, And it comprises a filter unit 30 for filtering the noise of the rectified power supply.

In addition, the switching unit 40 is configured to drive one or more switching elements using a rectified and filtered power source to generate a high output current. The output end of the switching unit is connected to the motor (M) of the compressor, a high output current of three phase (U / V / W) is applied to the motor.

At this time, the driving device is connected to any one of the line current of the three-phase current applied to the compressor motor, the compressor line current detection unit 50 for sensing the current directly applied to the compressor motor through the line current stage It is configured to include more.

In the related art, the compressor is connected to the input terminal of the driving device to sense the line current of the power supply terminal to control the compressor. In the present invention, the accuracy of the compressor control can be improved by detecting the current applied directly to the compressor motor (M). have.

The control unit 60 of the present invention is connected to the compressor line current detection unit 50 to determine whether the detected current exceeds the reference value. The reference value is a setting value for determining whether overcurrent is applied to the motor, and is a value changeable by the designer according to the performance of the compressor motor.

Further comprising a pulse width variable portion 70 for varying the width of the driving pulse applied to the compressor motor under the control of the controller 60, the pulse width variable portion is the control of the controller when the normal load 4, the driving pulse having the basic pulse width as shown in FIG. 4 is applied to the compressor motor M. In the case of an overload, the driving pulse width is increased as shown in FIG. 5 and then the driving pulse is applied to the compressor motor.

That is, as the pulse width of the high section is increased, the voltage applied to the compressor motor is increased, so that the motor torque is increased and stable rotation is possible without excessive increase of the compressor current even under an overload condition.

Accordingly, the control unit 60 determines that the pulse width variable unit maintains the driving pulse width as shown in FIG. 4 according to the normal frequency-voltage characteristic as shown in G1 of FIG. 3 as a result of the determination. To control.

4 illustrates a driving pulse for driving the compressor motor when the compressor is driven at a normal level of cooling load or heating load, which is 100V-60Hz.

However, when the current sensed as a result of the determination exceeds the reference value, that is, when an overcurrent is applied to the compressor as the difference between the room temperature and the target temperature changes rapidly, the control unit 60 of FIG. In order to increase the voltage at the same frequency as G2 and G2 ', the pulse width variable part 70 is controlled to increase the driving pulse width as shown in FIG. As shown in FIG. 5, the driving pulse applied to the motor after the pulse width is variable is 160V-60Hz, and it can be seen that a higher voltage (60% increase) is applied to the motor compared to FIG. 4.

3A and 3B illustrate an example in which the line voltage is increased in a specific frequency band by the controller 60. In the first embodiment of FIG. 3A, a higher line voltage is applied to the motor in the low frequency band. The higher the frequency, the lower the rate of increase of the line voltage. To this end, the control unit increases the increase rate of the pulse width in the low frequency band, and decreases the increase rate of the pulse width in the high frequency band.

On the other hand, in the second embodiment of FIG. 3B, the line voltage is increased at the same rate in a predetermined frequency band. For this purpose, the controller increases the pulse width at the same rate in the predetermined frequency band.

Looking at the drive method of the inverter air conditioner of the present invention configured as described above with reference to FIG.

First, the line current applied to the compressor motor is sensed by the compressor line current detecting unit (S1).

The controller compares whether the detected current value exceeds a reference value for overload determination to determine an overload / normal load state. If the reference value is exceeded, an overload condition is reached. If the reference value is lower than the reference value, a normal load condition is obtained.

If the load is normal, the compressor motor is driven by generating a driving pulse while maintaining the predetermined pulse width. If the load is overloaded, the compressor motor is driven by generating a driving pulse having a high pulse width. S5)

The pulse width control (PWM) of the driving pulse is applied to the compressor motor at the time of overload to prevent the motor's line current from being excessively raised, and to prevent the motor coil from being burned out due to the overcurrent.

As described above with reference to the drawings illustrated with respect to the drive device and the control method of the inverter air conditioner according to the present invention, the present invention is not limited by the embodiments and drawings disclosed herein, the field to which the present invention belongs It is possible to apply within the scope of protection of the technical idea of the present invention by those skilled in the art.

The drive device and control method of the inverter air conditioner of the present invention configured as described above has the effect that the accuracy of the compressor control is improved by sensing the overcurrent at the line current stage of the compressor. In addition, when the overcurrent is detected, the drive pulse width of the inverter is increased to increase the voltage applied to the compressor motor, thereby enabling stable operation of the compressor even under overload conditions, and preventing heat loss of the coil in the motor due to overcurrent. have.

Claims (7)

A switching unit for generating a high output current by driving one or more switching elements using a DC power supply; a compressor line current sensing unit for sensing a current flowing through a predetermined line current stage applied from the switching unit to the compressor motor; The controller detects an overcurrent state by comparing whether the current sensed by the compressor line current detection unit exceeds a reference value, and in case of an overcurrent state, a controller for issuing a control signal for increasing a pulse width and applying it to the compressor motor according to the control signal of the controller. The drive device of the inverter air conditioner, characterized in that it comprises a pulse width variable portion for varying the width of the driving pulse. In claim 1, The drive unit of the inverter air conditioner, characterized in that it further comprises a power stage to which the AC power is supplied, a rectifier for rectifying the AC power through the rectifier diode, and a filter unit for filtering the noise of the rectified power to apply to the switching unit . In claim 1, The control unit is a drive device of the inverter air conditioner, if the current sensed by the compressor line current detection unit is less than the reference value, to determine the normal current state to maintain the width of the drive pulse. In claim 3, The controller controls the pulse width to increase in the overcurrent state, so that the voltage applied to the compressor motor is increased by 60% than the voltage of the normal current state.  A first step in which a line current applied to the compressor motor is sensed, a second step in determining an overload / normal load state by comparing whether the detected current value exceeds a reference value for overload determination; The compressor motor is driven by a third step of generating a driving pulse having an increased width, and generating a driving pulse by maintaining a predetermined pulse width in a normal load state, and by a driving pulse whose pulse width is controlled by the third step. A drive method of an inverter air conditioner, characterized in that it comprises a fourth step. In claim 5, And in case of the overload state of the third step, the pulse width is increased at a constant rate in a predetermined low frequency band. In claim 5, And in case of the overload state of the third step, the pulse width is increased at a different rate according to a frequency band.

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