KR20230069650A - Power converting apparatus and home appliance including the same - Google Patents

Abstract

According to an embodiment of the present invention, a power conversion device and a home appliance comprise: an inverter having a switching element and converting direct current power to alternating current power to drive a motor; a gate driver that drives the switching element; a current detection unit that detects a current flowing in the switching element; and a comparator to which a voltage and a reference voltage based on data detected by the current detection unit are inputted, wherein an output terminal is connected to the gate driver in the comparator.

Description

Power converting apparatus and home appliance having the same {Power converting apparatus and home appliance including the same}

The present invention relates to a power conversion device and a home appliance including the same, and more particularly, to a power conversion device capable of protecting an inverter switching element and a home appliance including the same.

The power converter is a device that converts input power and supplies the converted power. Such a power conversion device may be disposed in a home appliance to convert input power into power for driving the home appliance.

Meanwhile, the power conversion device may include a switching element. For example, an inverter included in the power conversion device may include various semiconductor devices. For example, insulated gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and the like are widely used as switching elements.

Korean Patent Publication No. 10-2000-0006447 discloses a power conversion device using an insulated gate bipolar transistor (IGBT) device. According to an input control signal (eg, a PWM signal), a gate driver IC may supply a predetermined voltage to the IGBT switch to turn on the IGBT switch. When the gate voltage of the IGBT switch exceeds the threshold voltage, the IGBT switch may be turned on.

Meanwhile, the power conversion device may include a protection circuit that protects the switching element. In general, the protection circuit detects the current flowing through the switching element and blocks driving of the switching element when it is sensed that a certain amount of current or more flows through the switching element.

An object of the present invention is to provide a power conversion device capable of effectively protecting a switching element and a home appliance including the same.

An object of the present invention is to provide a power conversion device capable of protecting a switching element while minimizing the influence of a temperature change of the switching element and a home appliance including the same.

A power conversion device and home appliance according to an embodiment of the present invention for achieving the above object include a switching element, an inverter converting DC power into AC power to drive a motor, a gate driver driving the switching element, A current detector detecting a current flowing through the switching element, and a comparator inputting a voltage based on data detected by the current detector and a reference voltage and having an output terminal connected to the gate driver.

Power converters and home appliances according to embodiments of the present invention may further include a pull-up resistor having one end connected to an output terminal of the comparator and the other end connected to a constant voltage.

The power conversion device and home appliance according to an embodiment of the present invention may further include a capacitor connected to an output terminal of the comparator and the pull-up resistor.

An output terminal of the comparator is connected to the DESAT pin of the gate driver, and a switching operation of the switching element may be stopped when a predetermined voltage or more is applied to the DESAT pin.

The power converter and home appliance according to an embodiment of the present invention may further include a DESAT resistor disposed between an output terminal of the comparator and a DESAT pin of the gate driver.

The power conversion device and home appliance according to an embodiment of the present invention may further include a reverse flow prevention diode disposed between an output terminal of the comparator and a DESAT pin of the gate driver.

The switching element may be an insulated gate bipolar transistor.

The current detector may include a shunt resistor connected to the switching element.

The current detector and the comparator may be connected to a lower arm switching element of the inverter.

According to at least one of the embodiments of the present invention, the switching element can be effectively protected.

In addition, according to at least one of the embodiments of the present invention, the influence of the temperature change of the switching element can be minimized.

Meanwhile, other various effects will be disclosed directly or implicitly in detailed descriptions according to embodiments of the present invention to be described later.

1 is an example of a circuit diagram of a power conversion device according to an embodiment of the present invention.
2 is an example of a circuit diagram of a power conversion device according to an embodiment of the present invention.
3 is a diagram showing the relationship between voltage and current according to the temperature of a switching element.
4 to 7 are diagrams referenced for description of a switching element protection circuit according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to these embodiments and can be modified in various forms.

In the drawings, in order to clearly and concisely describe the present invention, parts not related to the description are omitted, and the same reference numerals are used for the same or extremely similar parts throughout the specification.

On the other hand, the suffixes "module" and "unit" for components used in the following description are simply given in consideration of the ease of preparation of this specification, and do not themselves give a particularly important meaning or role. Accordingly, the “module” and “unit” may be used interchangeably.

Also, in this specification, terms such as first and second may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

Meanwhile, the power conversion device described in this specification may be a power conversion device included in a home appliance. Home appliances may include refrigerators, washing machines, dryers, air conditioners, dehumidifiers, cooking appliances, vacuum cleaners, and the like.

1 is an example of a circuit diagram of a power conversion device according to an embodiment of the present invention.

Referring to FIG. 1, a power conversion device 400 according to an embodiment of the present invention includes a converter 410 that converts input power into DC power and outputs it to a DC terminal, a converter control unit 415, and a DC terminal. An inverter 420 having a connected capacitor C, a plurality of switching elements, and converting DC power from the capacitor C to AC, and an inverter controller 430 controlling the inverter 420. can The power converter 400 may further include an input voltage detector (A), a dc voltage detector (B), an input current detector (D), and an output current detector (E).

Meanwhile, in FIG. 1 and below, a case in which the power conversion device 400 is used as a motor driving device that converts power input from the commercial AC power source 201 and supplies it to the motor 250 is exemplified. In this case, the power conversion device 400 may be referred to as a motor driving device or a motor driving unit. Alternatively, the power conversion device 400 may convert input power and supply it to a load. In FIG. 4 , an example in which the power conversion device 400 is implemented as a motor driving device is mainly described, but the present invention is not limited thereto.

The converter 410 may convert commercial AC power 201 into DC power and output the converted power. To this end, the converter 410 may include a rectifier (510 in FIG. 2 ). In addition, it is also possible to further include a reactor (not shown).

A smoothing capacitor C is connected to the output terminal of the converter 410 . The capacitor C may store power output from the converter 410 . Since the power output from the converter 410 is dc power, it may be referred to as a dc stage capacitor.

The inverter 420 may output the converted AC power to the motor 250 .

Referring to FIG. 1 , the input voltage detector A may detect an input voltage Vs from an input AC power supply 201 .

The input voltage detector A may include a resistance element, an OP AMP, or the like for voltage detection. The detected input voltage Vs may be applied to the inverter controller 230 as a discrete signal in a pulse form.

Meanwhile, the zero crossing point of the input voltage can also be detected by the input voltage detector A.

The input current detector D may detect the input current is input from the commercial AC power supply 201 . To this end, as the input current detector D, a current transformer (CT), a shunt resistor, or the like may be used. The detected input current (is) is a pulse-shaped discrete signal and may be input to the inverter control unit 430 to calculate power consumption.

Next, a capacitor C may be provided at an output terminal of the converter 410 to store or smooth the power converted by the converter 410 . Both ends of the capacitor C at this time may be referred to as a dc stage. Therefore, the capacitor C may also be referred to as a dc capacitor.

Meanwhile, the converter control unit 415 generates a converter switching control signal Scc based on the input voltage Vs, the input current Is, and the dc link voltage Vdc, and outputs the converter switching control signal Scc to the converter 410. can

The dc terminal voltage detector (B) may detect the dc terminal voltage (Vdc) of both ends of the smoothing capacitor (C). To this end, the dc link voltage detection unit (B) may include a resistance element, an amplifier, and the like. The detected dc link voltage (Vdc) may be input to the inverter control unit 430 as a discrete signal in the form of a pulse.

The inverter 420 may drive the motor 250 . To this end, the inverter 420 is provided with a plurality of inverter switching elements, and converts DC power (Vdc) smoothed by the on/off operation of the switching elements into three-phase AC power of a predetermined frequency, and the three-phase synchronous motor 250 ) can be output.

In the inverter 420, an upper arm switching element and a lower arm switching element connected in series to each other form a pair, and a total of three pairs of upper and lower arm switching elements are connected in parallel to each other. A diode is connected in anti-parallel to each switching element.

The switching elements in the inverter 420 perform an on/off operation of each switching element based on the inverter switching control signal Sic from the inverter control unit 430 . As a result, three-phase AC power having a predetermined frequency is output to the three-phase synchronous motor 250 .

The inverter controller 430 may control a switching operation of the inverter 420 . To this end, the inverter controller 430 may receive the output current i _o detected by the output current detector E.

The inverter controller 430 outputs the inverter switching control signal Sic to the inverter 420 to control the switching operation of the inverter 420 . The inverter switching control signal Sic is a pulse width modulation (PWM) switching control signal, which is generated and output based on the output current value _io detected by the output current detector E.

The output current detector E detects the output current _io flowing between the inverter 420 and the three-phase motor 250 . That is, the current flowing through the motor 250 is detected. The output current detection unit E may detect all of the output currents ia, ib, and ic of each phase, or may detect the output currents of two phases using three-phase balance.

The output current detector E may be positioned between the inverter 420 and the motor 250, and a current transformer (CT), a shunt resistor, or the like may be used to detect the current.

When shunt resistors are used, it is possible that three shunt resistors are located between the inverter 420 and the synchronous motor 250 or have one end connected to the three lower arm switching elements of the inverter 420, respectively. On the other hand, using three-phase equilibrium, it is also possible that two shunt resistors are used. Meanwhile, when one shunt resistor is used, the corresponding shunt resistor may be disposed between the aforementioned capacitor C and the inverter 420 .

The detected output current (i _o ) may be applied to the inverter controller 430 as a discrete signal in a pulse form, and the inverter switching control signal (Sic) is generated based on the detected output current ( _io ). is created

Meanwhile, the motor 250 may be a three-phase motor. The motor 250 has a stator and a rotor, and each phase AC power of a predetermined frequency is applied to the coils of the stator of each phase (phases a, b, and c) to rotate the rotor. .

Such a motor 250 includes, for example, a surface-mounted permanent-magnet synchronous motor (SMPMSM), an interior permanent magnet synchronous motor (IPMSM), and a synchronous relay. A Synchronous Reluctance Motor (Synrm) and the like may be included. Among them, SMPMSM and IPMSM are Permanent Magnet Synchronous Motor (PMSM) applied with permanent magnet, and Synrm is characterized by no permanent magnet.

Meanwhile, the converter 410 and the inverter 420 include switching elements. For example, the converter 410 and the inverter 420 may include IGBT switching elements.

2 is an example of a circuit diagram of a power conversion device according to an embodiment of the present invention.

Referring to FIGS. 1 and 2 , the power conversion device according to an embodiment of the present invention includes a converter 410 that converts input AC power into DC power and outputs it, and smooths and stores the output power of the converter 410. and an inverter 420 having a plurality of switching elements and converting DC power from the smoothing capacitor C into AC power to drive a motor.

According to an embodiment, the converter 410 further includes an inductor (L) and a diode (D) connected in series with each other, and the switching element (S) is connected between the inductor (L) and the diode (D). can

Meanwhile, the converter 410 includes a rectifier 510 that rectifies input AC power and outputs the rectified power to the converter, and between the rectifier 510 and the smoothing capacitor C, the rectified power from the rectifier 510 It may include a boost converter 520 that boosts and outputs.

The boost converter 520 is between the rectifier 510 and the inverter 420, an inductor L and a diode D connected in series with each other, and a switching element S connected between the inductor L and the diode D. ) is provided. When the switching element S is turned on, energy is stored in the inductor L, and when the switching element S is turned off, the energy stored in the inductor L is output through the diode D. .

In particular, in the power conversion device using the low-capacity dc capacitor (C), a boosted voltage, that is, an offset voltage, may be output from the boost converter 520 .

The converter controller 415 may control turn-on timing of the switching element S in the boost converter 520 . Accordingly, the converter switching control signal Scc for turn-on timing of the switching element S may be output.

In the inverter 420, a pair of upper and lower arm switching elements Sa, Sb, and Sc and lower arm switching elements S'a, S'b, and S'c connected in series with each other are formed, and a total of three pairs of upper and lower arms The switching elements Sa, Sb, and Sc (S'a, S'b, and S'c) are connected in parallel with each other. A diode may be connected in anti-parallel to each switching element.

The output current detector E may be positioned between the inverter 420 and the motor 250, and a current transformer (CT), a shunt resistor, or the like may be used to detect the current.

When a shunt resistor is used, three shunt resistors are located between the inverter 420 and the synchronous motor 250, or three lower arm switching elements (S'a, S'b, S'c) of the inverter 420 ), it is possible that one end is connected to each.

The switching elements Sa, Sb, and Sc (S'a, S'b, and S'c) may be insulated gate bipolar transistors (IGBTs), and a gate driver is an IGBT switch. can drive

On the other hand, it is necessary to cut off the IGBT overcurrent to protect the compressor, motor, and IC. The gate driver may include a protection circuit function to protect the switching elements Sa, Sb, and Sc (S'a, S'b, and S'c). Specifically, this protection circuit function is a desaturation function that stops the switching operation of the switching element when a voltage higher than a certain level is applied to the gate driver's input pin (called Desat stage, Desat pin, etc., hereinafter referred to as Desat pin). can For this protection circuit function, the saturation voltage (Vce) between the collector terminal (C) and the emitter terminal (E) of the switching element was used.

3 is a diagram showing the relationship between voltage and current according to the temperature of a switching element.

Referring to FIG. 3 , the saturation voltage (Vce) between the collector terminal (C) and the emitter terminal (E) of the switching element changes according to the internal temperature (Tvj). Accordingly, saturation between the collector terminal (C) and the emitter terminal (E) of the switching element may be determined differently according to the internal temperature (Tvj).

For example, when the internal temperature (Tvj) is 25°C, the saturation voltage (Vce) for a 90A collector current (IC) to flow is 2.0V, but when the internal temperature (Tvj) is 150°C, the saturation voltage (Vce) is 2.5V. do. In addition, at the same Vce voltage, the Desat sensing current is 53A when the internal temperature (Tvj) is 25°C, and 40A when the internal temperature (Tvj) is 150°C. Therefore, the current changes with temperature. In order to prevent malfunction/false detection, overcurrent must be blocked at a certain level. The IGBT current and Vce voltage of the Desat sensing circuit have proportional characteristics, but the characteristics of the Ic-Vce voltage change according to the Tj temperature of the IGBT, so a design reflecting this is necessary.

4 to 7 are diagrams referenced for description of a switching element protection circuit according to an embodiment of the present invention.

Referring to FIGS. 4 and 5 , the power conversion device according to an embodiment of the present invention includes a predetermined switching element (SW), a gate driver 110 driving the switching element (SW), and the gate driver 110 ) and a comparator 120 connected to

The switching element (SW) is a switching element (Sa, Sb, Sc) (S'a, S'b, S' provided in the inverter 420 that converts DC power into AC power to drive the motor 250) c) may be at least one of That is, the switching element SW may be at least one of upper arm switching elements Sa, Sb, and Sc and lower arm switching elements S'a, S'b, and S'c. The switching element SW may be an insulated gate bipolar transistor.

Meanwhile, the current detector E may sense the current flowing through the switching element SW. A voltage based on data sensed by the current detector E and a reference voltage may be input to the comparator 120 . An output terminal of the comparator 120 may be connected to the gate driver 110 to output a comparison result between a voltage based on data sensed by the current detector E and a reference voltage.

According to an embodiment of the present disclosure, the current detector E may include a shunt resistor Rs connected to the switching element SW. In this case, the switching element SW may be at least one of the lower arm switching elements S'a, S'b, and S'c to which the shunt resistor Rs is connected. The current detector E and the comparator 120 may be connected to the lower arm switching element of the inverter 420 .

One shunt resistor Rs may be connected to the lower arm switching elements S'a, S'b, and S'c. In this case, one input terminal of the comparator 120 is connected to a node between the lower arm switching elements S'a, S'b, and S'c and the shunt resistor Rs to generate a phase current sensing voltage VOC_CURRENT This may be input to the comparator 120.

A shunt resistor Rs may be connected to each of the lower arm switching elements S'a, S'b, and S'c. In this case, one input terminal of the comparator 120 is connected to each of the nodes between the lower arm switching elements S'a, S'b, and S'c and the shunt resistors Rs, so that the phase current sensing voltage VOC_CURRENT ) may be input to the comparator 120. Depending on the embodiment, a plurality of comparators 120 may be provided and connected to each shunt resistor Rs.

Meanwhile, an output terminal of the comparator 120 may be connected to a Desat pin (V _DESAT ) of the gate driver 110 . A phase current sensing voltage (VOC_CURRENT) and a reference voltage (VOC_REF) are input to two input terminals of the comparator 120, and the comparator 120 may output a comparison result through a Desat pin (V _DESAT ). The reference voltage VOC_REF may be generated by the reference voltage generator 160 . For example, the reference voltage generator 160 may simply generate a reference voltage by being composed of a constant voltage and a distribution resistor.

Meanwhile, the output terminal of the comparator 120 is connected to the DESAT pin of the gate driver 110, and performs a Desat operation to stop the switching operation of the switching element SW when a predetermined voltage or more is applied to the DESAT pin. can do.

Meanwhile, a pull-up resistor 140 may be connected to an output terminal of the comparator 120 . One end of the pull-up resistor 140 may be connected to the output terminal of the comparator 120 and the other end may be connected to a constant voltage. Accordingly, the output of the comparator 120 may be maintained. For example, when the pull-up resistor 140 is connected to a 5V constant voltage and high is output from the comparator 120, the output terminal of the comparator 120 can maintain the 5V voltage.

Accordingly, a constant 5V voltage may be applied to the Desat pin (V _DESAT ) of the gate driver 110, and the Desat operation may be performed without malfunction/false detection.

Meanwhile, a DESAT resistor 130 disposed between an output terminal of the comparator 120 and a DESAT pin of the gate driver 110 may be further included.

A voltage corresponding to the sum of the 5V voltage formed at the output terminal of the comparator 120 and the voltage across the DESAT resistor 130 may be input to the DESAT pin of the gate driver 110 in case of overcurrent/overvoltage. Accordingly, the Desat operation can be performed without malfunction/false detection.

Meanwhile, a backflow prevention diode 190 may be further disposed between the output terminal of the comparator 120 and the DESAT pin of the gate driver 110 .

The gate driver 110 detects overcurrent when 9V or more enters the DESAT pin and performs a protective operation. For example, the voltage Vf across the reverse current prevention diode 190 and the When the sum of the voltage and the 5V voltage formed at the output terminal of the comparator 120 exceeds 9V, a Desat operation of stopping the switching operation of the switching element SW may be performed.

According to an embodiment of the present invention, the criterion for performing the protection operation does not include e, which is affected by temperature. According to the embodiment of the present invention, after sensing the current using the shunt resistor (Rs) without using Vce, when the current is above a certain level, the output is configured to be High (5V) through the comparator 120, so that the temperature Stable control is possible without being affected.

If the IGBT overcurrent occurs, the voltage across the shunt resistor Rs is greater than the reference voltage, and the comparator 120 may output a high signal after level comparison. Since a voltage higher than the reference value (for example, 9V) is input to the Desat terminal, it is determined to be an error, and the PWM signal supply to the IGBT is cut off and a fault can be generated. Accordingly, erroneous detection and erroneous operation due to temperature effects can be prevented, and product quality can be improved.

Meanwhile, a capacitor 150 is connected to the output terminal of the comparator 120 and the pull-up resistor 140 to reduce noise and maintain output.

The Desat detection circuit of the gate drive IC is a protection circuit that cuts off the PWM signal when the voltage monitored through the Desat pin of the gate drive IC reaches a preset threshold voltage value.

The Desat detection circuit of the gate drive IC according to the embodiment of the present invention senses an overcurrent through a shunt resistor (Rs) without using the Vce voltage of the IGBT.

Meanwhile, the DESAT pin of the gate driver 110 includes a comparator 111, a current source (Isource), an input resistor 112, a diode 113, and a switch element 114 for switching the current flow direction of the current source (Isource). can be connected.

A capacitor 170 and a diode 180 connected in parallel may be disposed between the DESAT pin and the backflow prevention diode 190 . The voltage applied to the DESAT pin is applied to the DESAT pin after the capacitor 170 is charged, thereby preventing malfunction.

The comparator 111 of the gate driver 110 determines whether a predetermined level or higher (eg, 9V) is applied, and when a predetermined level or higher voltage is applied to the DESAT pin, the protection function operates.

Referring to FIG. 6 , according to the operation of the switch element 114 , when the switching element SW is in an off state, the current of the current source flows in a direction 610 toward the switch element 114 .

Referring to FIG. 7 , according to the operation of the switch element 114, the current of the current source flows in a direction 620 toward the comparator 120 when the switching element SW is on.

However, in the present invention, only the DESAT function can be used without using the Vce voltage as a criterion for protection operation.

Specifically, by setting the detector output voltage (VOC_CURRENT) as the comparator input voltage and the overcurrent fault level (Fault Level) as the comparator reference voltage reference voltage (VOC_REF), the comparator output is high when an overcurrent above the fault level occurs. ) is configured to be

For example, when the phase current sensing voltage VOC_CURRENT is greater than the reference voltage VOC_REF, the output voltage of the comparator 120 rises by 5V.

If the backflow prevention diode 190 is 0.65V at 500uA, the Desat terminal voltage during normal operation is as follows.

- VDESAT (during normal operation) = 10[kohm] X 500[uA] + 0.65V = 5.65V

When an overcurrent/overvoltage occurs and the output of the comparator 120 becomes high, 5V is added to the output voltage of the comparator 120, and the Desat terminal voltage is as follows.

- VDESAT (when the comparator operates due to overvoltage/overcurrent) = 5.65V + 5V = 10.65V

Therefore, VDESAT becomes larger than 9V, and a protection operation can be performed in response to overcurrent/overvoltage. According to an embodiment of the present invention, it is possible to detect an overcurrent of a certain level without being affected by the IGBT temperature and to protect the product.

The power conversion device according to the present invention and a home appliance having the same are not limited to the configuration and method of the embodiments described above, but the above embodiments are all of the embodiments so that various modifications can be made. Alternatively, some of them may be selectively combined.

In addition, although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present invention claimed in the claims. Of course, various modifications are possible by those skilled in the art, and these modifications should not be individually understood from the technical spirit or perspective of the present invention.

Converter: 410
Converter control: 415
Inverter: 420
Inverter Control: 430

Claims (10)

an inverter having a switching element and converting DC power into AC power to drive a motor;
a gate driver driving the switching element;
a current detector detecting a current flowing through the switching element; and,
and a comparator inputting a voltage based on the data sensed by the current detector and a reference voltage and having an output terminal connected to the gate driver. According to claim 1,
The power converter further comprising a pull-up resistor having one end connected to the output terminal of the comparator and the other terminal connected to a constant voltage. According to claim 1,
The power conversion device further comprising a; capacitor connected to the output terminal of the comparator and the pull-up resistor. According to claim 1,
The output terminal of the comparator is connected to the DESAT pin of the gate driver,
A power conversion device that stops the switching operation of the switching element when a predetermined voltage or more is applied to the DESAT pin. According to claim 4,
A DESAT resistor disposed between the output terminal of the comparator and the DESAT pin of the gate driver; According to claim 4,
The power converter further comprising a reverse flow prevention diode disposed between the output terminal of the comparator and the DESAT pin of the gate driver. According to claim 1,
The power conversion device of claim 1 , wherein the switching element is an insulated gate bipolar transistor. According to claim 1,
The power conversion device of claim 1, wherein the current detector includes a shunt resistor connected to the switching element. According to claim 1,
The current detector and the comparator are connected to the lower arm switching element of the inverter. A home appliance comprising a; power conversion device according to any one of claims 1 to 9.

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