KR20180036096A - Power transforming apparatus and air conditioner including the same - Google Patents

Abstract

The present invention relates to a power converter. Especially, the present invention relates to a power converter which can protect a switching element from overcurrent, and an air conditioner having the same. The power converter having a switching element comprises: a driver IC driving the switching element, and including a protection circuit function for protecting the switching element; and an element protection unit including a current sensing unit for sensing a current flowing the switching element and a comparator connected to an input pin of the protection circuit function by comparing a voltage value sensed by the current sensing unit with a reference voltage value, and operating the protection circuit function by applying a signal to the protection circuit function when the overcurrent flows in the switching element.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power conversion apparatus and an air conditioner including the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power conversion apparatus, and more particularly, to a power conversion apparatus capable of protecting a switching element from an overcurrent and an air conditioner including the same.

Generally, a compressor of an air conditioner uses a motor as a driving source. These motors are supplied with AC power from a power conversion device.

It is generally known that such a power conversion apparatus mainly constitutes a rectification section, a power factor control section, and an inverter type power conversion section.

First, the commercial voltage of the AC output from the commercial power source is rectified by the rectifying part. The voltage rectified in this rectifying part is supplied to a power converting part such as an inverter. At this time, the power converting unit generates AC power for driving the motor by using the voltage output from the rectifying unit.

In some cases, a DC-DC converter for improving the power factor may be provided between the rectification part and the inverter.

The driver (for example, a driver IC) for driving the switching element used in the DC-DC converter may include an overcurrent protection circuit to prevent burn-out of the switching element.

The overcurrent protection circuit detects the current flowing in the switching element and uses a method of shutting off the switching element when the switching element is detected to flow over a predetermined amount of current.

However, in monitoring the current applied to the switching device, the error range of monitoring may be increased depending on the temperature of the switching device and the peripheral circuit devices.

Therefore, there is a need for a method for effectively protecting the switching element by reducing the error range.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a power conversion apparatus and an air conditioner including the same that can effectively protect a switching device by reducing an error range when monitoring a current flowing through the switching device.

Also, it is an object of the present invention to provide a power conversion apparatus and an air conditioner including the power conversion apparatus that can effectively protect individual switching elements from the same elements as the inverter apparatus having a plurality of switching elements.

According to a first aspect of the present invention, there is provided a power conversion device including a switching device, the device comprising: a driver IC including a protective circuit function for driving the switching device and protecting the switching device; And a comparator that compares a voltage value sensed by the current sensing unit with a reference voltage value and is connected to an input pin of the protection circuit function, wherein the overcurrent And a device protection unit for applying a signal to the input pin of the protection circuit function to operate the protection circuit function when the protection circuit function is activated.

Here, the current sensing unit may include a shunt resistor connected to the emitter terminal or the source terminal of the switching element.

The device protection unit may further include a level adjuster between the comparator and an input pin of the protection circuit function for adjusting a level of a signal applied to the input pin of the protection circuit function.

At this time, the level controller may include: a resistor for lowering the voltage; A zener diode for determining the level of the signal; And a reverse current blocking diode positioned between the resistor and the zener diode.

Here, the switching device may be an insulated gate bipolar transistor included in an inverter device for driving a motor.

At this time, the inverter device includes a plurality of switching devices; And a plurality of driver ICs for driving the plurality of switching elements.

At this time, the device protection unit may be commonly connected to input pins of the protective circuit function of the plurality of driver ICs.

Here, the switching device may be an insulated gate bipolar transistor connected to an AC power source and provided in a DC-DC converter for controlling a power factor.

Here, the protection circuit function may be a function of stopping the switching operation of the switching element when a voltage exceeding a predetermined voltage is applied to the input pin of the protection circuit function.

According to a second aspect of the present invention, there is provided an air conditioner including the above power conversion device.

The present invention has the following effects.

First, the switching element protection performance can be improved by sensing the actual current flowing through the switching element Q1 regardless of the deviation of the Vce voltage of the switching element caused by the junction temperature, the gate (base) voltage,

Further, it is possible to effectively protect the individual switching elements in the case of an inverter device having a plurality of switching elements, for example, six switching elements.

As described above, according to the present invention, it is possible to sufficiently protect the switching element Q1 from an overcurrent and to prevent burnout (potato, deterioration, etc.) of the motor.

1 is a block diagram showing an example of a power conversion apparatus to which the present invention can be applied.
2 is a circuit diagram showing an example of a power conversion apparatus to which the present invention can be applied.
3 is a circuit diagram showing a power conversion apparatus including a switching device according to the first embodiment of the present invention.
4 is a graph showing the relationship between voltage and current according to the temperature of the switching element.
5 is a circuit diagram showing a power conversion device including a switching device according to a second embodiment of the present invention.
6 is a circuit diagram showing a power conversion device including a switching device according to the third embodiment of the present invention.

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

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and / or regions, such elements, components, regions, layers and / And should not be limited by these terms.

Fig. 1 is a block diagram showing an example of a power conversion apparatus, and Fig. 2 is a circuit diagram showing an example of a power conversion apparatus.

1 and 2, the power inverter 100 includes a rectifier 110 for rectifying an AC power source 10, a converter 120 for controlling the power factor of the DC voltage rectified by the rectifier 110, A converter control unit 130 for controlling the converter 120, an inverter 140 for outputting a three-phase AC current, an inverter control unit 150 for controlling the inverter 140 and a converter 120 and an inverter 140, And a DC short capacitor C between the first and second capacitors.

This inverter 140 outputs a three-phase alternating current, and this output current is supplied to the motor 200. Here, the motor 200 may be a compressor motor for driving the air conditioner. Hereinafter, the motor 200 is a compressor motor that drives the air conditioner, and the power inverter 100 is a motor driving device that drives such a compressor motor.

However, the motor 200 is not limited to a compressor motor and can be used in various applications using frequency-varying alternating voltages, for example, AC motors such as refrigerators, washing machines, electric trains, automobiles, and vacuum cleaners.

The motor driving apparatus 100 may further include a DC voltage detection unit B, an input voltage detection unit A, an input current detection unit D, and an output current detection unit E.

The motor drive apparatus 100 receives the AC power from the system, converts the power, and supplies the converted power to the motor 200.

The converter 120 converts the input AC power supply 10 into a DC power supply. The converter 120 may use a DC-DC converter operating as a power factor control (PFC) unit. In addition, such a DC-DC converter can use a boost converter. Optionally, the converter 120 may be a concept that includes the rectifier 110. Hereinafter, the converter 120 will be described by way of example using a step-up converter.

The rectifying unit 110 receives and rectifies the single-phase AC power supply 10 and outputs the rectified power to the converter 120 side. For this purpose, the rectifying part 110 can use a full-wave rectifying circuit using a bridge diode.

In this way, the converter 120 can perform the power factor improving operation in the process of stepping up and smoothing the voltage rectified by the rectifier 110.

The converter 120 includes an inductor L1 connected to the rectifying section 110, a switching device Q1 connected to the inductor L1, a capacitor C connected in parallel with the switching device Q1, And a diode D1 connected between the switching element Q1 and the capacitor C. [

The boost converter 120 is a converter that can obtain an output voltage higher than the input voltage. When the switching device Q1 is turned on, energy is stored in the inductor L1 while the diode D1 is shut off, And the output voltage is generated at the output terminal while the charge is discharged.

Further, when the switching element Q1 is interrupted, the energy stored in the inductor L1 at the time of the switching element Q1 is added and is transferred to the output terminal.

Here, the switching device Q1 may perform a switching operation by a separate pulse width modulation (PWM) signal. That is, the PWM signal transmitted from the converter control unit 130 is connected to the base (or gate) terminal of the switching element Q1, and the switching operation can be performed by the PWM signal.

The switching element Q1 may use a power transistor, for example, an insulated gate bipolar mode transistor (IGBT).

The IGBT is a switching device having a structure of a power MOSFET (metal oxide semi-conductor field effect transistor) and a bipolar transistor. The IGBT is a device capable of small driving power, high speed switching, high voltage conversion and high current density.

In this manner, the converter control unit 130 can control the turn-on timing of the switching element Q1 in the converter 120. [ Thus, the converter control signal Sc for the turn-on timing of the switching element Q1 can be output.

The converter control unit 130 may receive the input voltage Vs and the input current Is from the input voltage detection unit A and the input current detection unit B, respectively.

Optionally, such converter 120 and converter control 130 may be omitted. That is, the output voltage passing through the rectifying unit 110 can be charged to the DC short-circuit capacitor C or the inverter 140 can be driven.

The input voltage detecting section A can detect the input voltage Vs from the input AC power supply 10. [ For example, at the front end of the rectifying part 110. [

The input voltage detecting section A may include a resistance element, an OP AMP, or the like for voltage detection. The detected input voltage Vs can be applied to the converter control unit 130 to generate a converter control signal Sc as a discrete signal in the form of a pulse.

Next, the input current detection unit D can detect the input current Is from the input AC power supply 10. [ Specifically, it may be located at the front end of the rectifying section 110. [

The input current detection unit D may include a current sensor, a current transformer (CT), a shunt resistor, or the like, for current detection. The detected input voltage Is may be applied to the converter control unit 130 to generate the converter control signal Sc as a discrete signal in the form of a pulse.

The DC voltage detecting section B detects the voltage Vdc that pulsates the DC short-circuited capacitor C. For such power detection, a resistance element, OP AMP, or the like can be used. The voltage Vdc of the detected DC short capacitor C can be applied to the inverter control unit 150 as a discrete signal in the form of a pulse and is supplied to the DC voltage Vdc of the DC short capacitor C The inverter control signal Si can be generated based on the inverter control signal Si.

On the other hand, unlike the drawing, the detected DC voltage is applied to the converter control unit 130 and may be used for generating the converter control signal Sc.

The inverter 140 includes a plurality of inverter switching elements Qa, Qb, Qc, Qa ', Qb' and Qc ', and supplies the smoothed DC power source Vdc to a predetermined frequency Phase AC power supply of the three-phase motor 200, and outputs the three-phase AC power to the three-phase motor 200.

Specifically, the inverter 140 is a pair of the upper arm switching elements Qa, Qb, and Qc and the lower arm switching elements Qa ', Qb', and Qc 'connected in series to each other, The devices can be connected in parallel with each other.

As with the converter 120, the switching elements Qa, Qb, Qc, Qa ', Qb', Qc 'of the inverter can use power transistors, for example, an insulated gate bipolar mode transistor ; IGBT) can be used.

The inverter control unit 150 can output the inverter control signal Si to the inverter 140 in order to control the switching operation of the inverter 140. [ The inverter control signal Si is generated based on the output current io flowing to the motor 200 and the DC short voltage Vdc across the DC short capacitor C as a switching control signal of the pulse width modulation method And output. The output current io at this time can be detected from the output current detection unit E and the DC short voltage Vdc can be detected from the DC voltage detection unit B. [

The output current detection section E can detect the output current io flowing between the inverter 140 and the motor 200. [ That is, the current flowing in the motor 200 is detected. The output current detection unit E can detect all of the output currents ia, ib, ic of each phase or can detect the output currents of two phases using the three-phase balance.

The output current detection unit E may be located between the inverter 140 and the motor 200. For current detection, a current transformer (CT), a shunt resistor, or the like may be used.

3 is a circuit diagram showing a power conversion apparatus including a switching device according to the first embodiment of the present invention.

The switching element Q1 as shown in Fig. 3 includes a DC-DC converter 120 (see Figs. 1 and 2) and an inverter 140 (see Figs. 1 and 2) Lt; / RTI >

The switching element Q1 may be connected to the converter controller 130 or the driver IC implementing the inverter controller 150 through a level controller 134 for adjusting the voltage level (offset voltage). Hereinafter, an example in which the driver IC constitutes the converter controller 130 will be described.

The driver IC 130 may include a protective circuit function for protecting the switching element Q1. Specifically, such a protection circuit function is controlled by a desaturation stopping the switching operation of the switching element Q1 when a voltage equal to or greater than a certain magnitude is applied to an input pin (a desat terminal or a desat pin) Function.

In this Desat stage, a protection circuit 131 including a current source Isource, a comparator 132 and a protection circuit logic 133 are connected.

The protection circuit 131 may include a current source Isource, an input resistance Rin, and a switch element (MosFET) for switching the current flow direction of the current source.

The comparator 132 is set at a constant voltage level, for example, 9 V, and the protection function operates when a voltage of 9 V or more is applied to the desat stage.

The Desat circuit as the overcurrent protection circuit 131 operates the switch element MosFET so that the current of the current source flows in the same direction as "a" when the switching element Q1 is off and the switching element Q1 is turned on (On), it flows in the same direction as 'b'.

The current flowing in the direction of 'b' is applied to the switching element Q1 so as to detect the voltage Vce (referred to as saturation voltage) at the collector-emitter end of the switching element Q1 .

Accordingly, when it is detected that the overvoltage is applied to the switching element Q1 in the voltage detecting process, a voltage higher than a predetermined voltage (9 V) is applied to the desat stage of the driver IC 130 through the level controller 134 . As a result, the switching of the switching element Q1 is stopped and the switching element Q1 can be protected from the overcurrent.

The voltage applied to the desat stage is first charged to the capacitor C _blank connected between the driver IC 130 and the level adjuster 134 and then applied to the driver IC 130 through the level adjuster 134 do. As a result, malfunction of the protection circuit can be prevented.

The level regulator 134 includes a resistor R _DESAT for lowering the voltage, a zener diode Z _DESAT for determining the level of the signal, and a reverse current prevention diode D _DESAT located between the resistor and the zener diode. can do.

The Zener diode Dz connected between the driver IC 130 and the level controller 134 may prevent the driver IC 130 from applying excessive voltage.

When the function of the protection circuit 131 is sensed by sensing the Vce saturation voltage of the switching element Q1, the switching element Q1 can be sufficiently protected for a situation such as a short circuit.

However, as shown in Fig. 4, the Vce saturation voltage exhibits a large variation with temperature in relation to the current. That is, the Vce saturation voltage is affected by the junction temperature of the switching element Q1, the base (gate) voltage, and the like.

Referring to FIG. 4, when the temperature is 25 ° C., when the voltage Vce is 2.5 V, the current is about 40 A, but when the temperature is 150 ° C., the current increases to 60 A or more when the voltage Vce is 2.5 V .

Therefore, when the function of the protection circuit 131 is operated by the deviation of the Vce saturation voltage, the error range may be large.

5 is a circuit diagram showing a power conversion device including a switching device according to a second embodiment of the present invention.

The switching element Q1 as shown in FIG. 5 can be used in the DC-DC converter 120 and the inverter 140 used in the power conversion apparatus.

The switching element Q1 may be connected to a driver IC that implements the converter controller 130 or the inverter controller 150 through a level controller 330 that adjusts a voltage level (offset voltage). Hereinafter, an example in which the driver IC constitutes the converter controller 130 will be described.

In addition, the same description can be applied to the parts common to FIG. 3, and a detailed description will be omitted.

Referring to FIG. 5, a device protection unit 300 is connected to the switching device Q1 so that a protection circuit function is activated when an overcurrent flows in the switching device Q1.

As described above, this protection circuit function is a function of desaturation that stops the switching operation of the switching element Q1 when a voltage equal to or greater than a certain magnitude is applied to the input pin (Desat terminal) of the corresponding protection circuit function have.

The device protection unit 300 includes a current sensing unit 310 for sensing a current flowing through the switching device Q1 and a voltage detection unit 310 for comparing the voltage sensed by the current sensing unit 310 with a reference voltage, And a comparator 320 connected to an input pin (Desat stage).

When the overcurrent flows to the switching element Q1, the signal is applied to the input pin (Desat terminal) of the protection circuit function by the device protection unit 300 so that the protection circuit function can operate.

At this time, the current sensing unit 310 may include a shunt resistor Rs connected to the emitter terminal or the source terminal of the switching element Q.

The voltage sensed by the current sensing unit 310 is input to a comparator 320. The comparator 320 includes an operational amplifier 321, a first resistor R1 for setting a voltage for determining an overcurrent, 2 < / RTI > resistor R2.

As described above, the output voltage of the comparator 320 can be applied to the Desat stage of the driver IC 130 through the level adjuster 330 that adjusts the voltage level (offset voltage).

In Fig. 5, as an example, the shunt resistor Rs has a resistance value of 10 m [Omega], for example, if a current of 30 A is sensed, a voltage of 0.3 V can be sensed by Ohm's law.

Here, the comparator 320 normally used may have an output value of 5 V when it is a high signal, that is, when an overcurrent is detected, and when a voltage of 9 V or more is input to the Desat stage, A level controller 330 may be connected to compensate for the offset voltage. This offset voltage may be set, for example, to 5.5 V. [

As described above, the level adjuster 330 includes a resistor R _DESAT for lowering the voltage, a zener diode Z _DESAT for determining the level of the signal, and a reverse current prevention diode D _DESAT ).

The Zener diode Dz connected between the driver IC 130 and the level controller 330 may prevent the driver IC 130 from applying excessive voltage. The capacitor (C _Blank ) prevents the protection circuit from operating due to instantaneous noise or the like, thereby preventing malfunction of the protection circuit.

On the other hand, when the comparator 320 outputs a voltage of 9 V or more when the signal is a high signal, the level controller 330 may be omitted.

6 is a circuit diagram showing a power conversion device including a switching device according to the third embodiment of the present invention.

6, the device protection unit 300 is provided in the inverter device 150 for driving the motor 200 using six IGBTs Qa, Qb, Qc, Qa ', Qb', and Qc ' Respectively.

As described above, the plurality of switching elements Qa, Qb, Qc, Qa ', Qb' and Qc 'and the plurality of driver ICs 151, 152, 153, 154, 155 and 156 for driving the plurality of switching elements A single device protection unit 300 can be provided.

That is, the device protection unit 300 may be commonly connected to the desat pins of the protective circuit functions of the plurality of driver ICs 151, 152, 153, 154, 155, 156.

As described above, a level control unit 330 is provided between the device pin 300 and the input pin of the protective circuit function of each driver IC 151, 152, 153, 154, 155, And the level adjuster 330 may be omitted according to the output voltage of the comparator 320. [

Hereinafter, the operation of the protection function operating in the circuit shown in Figs. 5 and 6 will be described by way of example.

For example, it is assumed that a current of 30 A or more flows and an overcurrent is determined.

When 30 A corresponding to this overcurrent flows through the shunt resistor (Rs), the voltage across the shunt resistor (Rs) becomes 0.3 V by Ohm's law.

The voltage for determining the overcurrent of the comparator 320 is set to 3.6 V by voltage division by R1 (2.4K?) And R2 (6.2K?).

At this time, 0.3 V input to the comparator 320 is amplified to 3.6 V from the OP Amp 321, and is compared with a determination voltage for determining an overcurrent, and a voltage of 5 V is output from the comparator 320.

The output voltage (5 V) of the comparator 320 is summed with the offset voltage (5.5 V) of the level regulator 330 and applied to the desat pin to operate the protection circuit.

In the case of FIG. 6, the protection operation can be performed only in the corresponding driver IC in which an overcurrent flows when an overcurrent flows in any one of the switching elements.

If the device protection unit 300 is not configured as shown in FIG. 6, it is not possible to protect all the switching devices when a plurality of switching devices are used. In the case where the remaining switching devices are protected by configuring a switch or an additional circuit, There is a risk of burnout of the switching element due to the time difference of the operation.

However, according to the present invention, it is possible to improve the performance of the switching element protection by sensing the actual current flowing through the switching element Q1 regardless of the deviation of the Vce voltage generated by the junction temperature, the gate (base) voltage,

In addition, as described above, it is possible to effectively protect the individual switching elements in the case of an inverter device having a plurality of switching elements, for example, six switching elements.

As described above, according to the present invention, it is possible to sufficiently protect the switching element Q1 from an overcurrent and to prevent burnout (potato, deterioration, etc.) of the motor.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

100: power converter 110: rectifying part
120: converter 130: converter control unit
140: inverter 150: inverter controller
200: motor 300:
310: current sensing unit 320: comparator
330:

Claims (10)

A power conversion device comprising a switching device,
A driver IC including a protective circuit function for driving the switching element and protecting the switching element; And
And a comparator that compares a voltage value sensed by the current sensing unit with a reference voltage value and is connected to an input pin of the protection circuit function, And a device protection unit for applying a signal to an input pin of the protection circuit function to cause the protection circuit function to operate. The power conversion apparatus of claim 1, wherein the current sensing unit includes a shunt resistor connected to an emitter terminal or a source terminal of the switching element. The device according to claim 1,
Further comprising a level adjuster between the comparator and an input pin of the protective circuit function for adjusting a level of a signal applied to an input pin of the protective circuit function. The apparatus of claim 3,
A resistor for lowering the voltage;
A zener diode for determining the level of the signal; And
And a reverse current prevention diode disposed between the resistor and the Zener diode. 2. The switching device according to claim 1,
Wherein the insulated gate bipolar transistor is an insulated gate bipolar transistor included in an inverter device for driving a motor. 6. The inverter device according to claim 5,
A plurality of switching elements; And
And a plurality of driver ICs for driving the plurality of switching elements. The power conversion apparatus according to claim 6, wherein the device protection unit is commonly connected to input pins of the protection circuit function of the plurality of driver ICs. The power converter according to claim 1, wherein the switching device is an insulated gate bipolar transistor connected to an AC power source and provided in a DC-DC converter for controlling a power factor. The power conversion apparatus according to claim 1, wherein the protection circuit function is a function of desaturation for stopping the switching operation of the switching element when a voltage exceeding a predetermined voltage is applied to the input pin of the protection circuit function. An air conditioner comprising the power conversion device according to any one of claims 1 to 9.

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