KR102174638B1 - Power transforming apparatus having noise reduction function, compressor including the same and the method for the same - Google Patents

Abstract

The present invention relates to a power conversion device, and more particularly, to a power conversion device capable of reducing electromagnetic interference (EMI) noise, a compressor including the same, and a control method thereof. The present invention includes an inverter for generating an AC signal for driving a motor including a plurality of switching elements; A gate driver driving the plurality of switching elements; A variable resistance part connected between the gate driver and the switching element; An output current detection unit detecting an output current of the inverter; And a control unit transmitting a control signal to the gate driver and transmitting a signal for varying a resistance value to the variable resistance unit to have a different modulation resistance value according to the output current sensed by the output current detection unit. have.

Description

Power transforming apparatus, a compressor including the same, and a control method thereof, including the same and the method for the same.

The present invention relates to a power conversion device, and more particularly, to a power conversion device capable of reducing electromagnetic interference (EMI) noise, a compressor including the same, and a control method thereof.

In general, compressors use a motor as a driving source. AC power is supplied to such a motor from a power conversion device.

It is generally known that such a power conversion device mainly comprises a rectifying unit, a power factor control unit, and an inverter type power conversion unit.

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

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

Such an inverter converts power using switching elements that switch at high speed, and electromagnetic interference (EMI) noise may occur during this process.

In addition, as electric devices are increasingly evolving to include smart functions, EMI noise due to high-speed switching is getting worse and standby power is also getting worse.

In order to reduce such EMI noise, a noise filter core may be used or a circuit for frequency modulation phase delay may be used.

However, when only the noise filter core is used, such noise reduction performance is deteriorated, and a circuit for frequency modulation phase delay requires a complex circuit configuration.

In order to reduce this noise, a filter of an inductor and a capacitor is additionally installed to limit it, and an EMC film is used, and a ground path is also manufactured. In addition to these means, an inductor may be mounted on the winding.

If such a method is applied, the noise reduction effect is improved, but the overall circuit driving efficiency decreases, occupies a large volume, and may cause an increase in manufacturing cost.

Accordingly, there is a need for a method capable of improving the performance of reducing EMI noise without a complicated circuit configuration.

The technical problem to be achieved by the present invention is a power conversion device capable of efficiently improving EMC and EMI characteristics while minimizing at least one of additional cost/circuit change/additional area for circuit configuration, a compressor including the same, and a control thereof I want to provide a way.

As a first aspect for achieving the above technical problem, the present invention includes an inverter for generating an AC signal for driving a motor including a plurality of switching elements; A gate driver driving the plurality of switching elements; A variable resistance part connected between the gate driver and the switching element; An output current detection unit detecting an output current of the inverter; And a control unit transmitting a control signal to the gate driver and transmitting a signal for varying a resistance value to the variable resistance unit to have a different modulation resistance value according to the output current sensed by the output current detection unit. have.

In addition, the variable resistance unit may be a digital variable resistance whose resistance value is adjusted according to a voltage value transmitted from the control unit.

In addition, the modulation resistance value may increase according to the output current sensed by the output current detector.

In addition, the modulation resistance value may increase in proportion to the output current sensed by the output current detection unit.

In addition, the control unit may control the variable resistance unit such that the modulation resistance value determined according to the output current sensed by the output current detection unit varies.

In addition, the controller may control the variable resistance unit so that the modulation resistance value varies within a predetermined range around the determined modulation resistance value.

As a second point of view for achieving the above technical problem, the present invention can provide a compressor including the power conversion device described above.

As a third aspect for achieving the above technical problem, the present invention provides an inverter including a plurality of switching elements to generate an AC signal for driving a motor, a gate driver for driving the plurality of switching elements, and the gate driver and the A method of controlling a power conversion device including a variable resistor connected between switching elements, the method comprising: sensing an input voltage and an output current of the inverter; Controlling the switching element by transmitting a control signal to the gate driver; And outputting a control voltage to the variable resistance unit so as to have different modulation resistance values according to a change in the output current.

In addition, in the step of outputting the control voltage to the variable resistance unit, the modulation resistance value may be controlled to increase in proportion to the output current.

In addition, the outputting of the control voltage to the variable resistor may include determining a control voltage of the variable resistor according to a change in the output current; Varying the determined control voltage within a predetermined range; And outputting the variable control voltage.

According to the present invention, noise can be dispersed by having a substantially aperiodic PWM driving voltage by resistance value modulation, and thus EMC and EMI can be improved.

As described above, according to an embodiment of the present invention, it is possible to improve EMC and EMI by stabilizing the driving signal.

In addition, while improving EMC and EMI, the overall circuit driving efficiency does not decrease, the volume of the circuit does not increase, and the manufacturing cost does not increase.

1 is a block diagram showing a power conversion device according to an embodiment of the present invention.
2 is a circuit diagram showing a power conversion device according to an embodiment of the present invention.
3 is a block diagram showing a part of a power conversion device according to an embodiment of the present invention.
4 is a graph showing a previous term according to an input voltage of a variable resistor of a power conversion device according to an embodiment of the present invention.
5 is a flowchart illustrating a method of controlling a power conversion device according to an embodiment of the present invention.
6 is a flow chart showing a specific process of controlling a variable resistor of the power conversion device according to an embodiment of the present invention.
7 is a signal diagram showing a driving signal of a power conversion device according to an embodiment of the present invention.

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

While the present invention allows various modifications and variations, specific embodiments thereof are illustrated and shown in the drawings, and will be described in detail below. However, it is not intended to limit the present invention to the particular form disclosed, but rather the present invention encompasses all modifications, equivalents and substitutions consistent with the spirit of the present invention as defined by the claims.

When an element such as a layer, region or substrate is referred to as being “on” another component, it will be understood that it may exist directly on another element or there may be intermediate elements between them. .

Although terms such as first, second, etc. may be used to describe various elements, components, regions, layers and/or regions, these elements, components, regions, layers and/or regions It will be understood that it should not be limited by these terms.

1 is a block diagram showing a power conversion device according to an embodiment of the present invention, Figure 2 is a circuit diagram showing a power conversion device according to an embodiment of the present invention.

1 and 2, the power conversion device 100 includes a rectifier 110 that rectifies the AC power supply 10, a converter 120 that boosts/depresses the DC voltage rectified by the rectifier 110 or controls the power factor. ), the converter control unit 130 for controlling the converter 120, the inverter 140 for outputting three-phase AC current, the inverter control unit 150 for controlling the inverter 140, and the converter 120 and the inverter 140 It may include a DC-link capacitor (C) between.

The inverter 140 outputs a three-phase alternating current, and this output current may be supplied to the motor 200. Here, the motor 200 may be a compressor motor driving the air conditioner. Hereinafter, it will be described as an example that the motor 200 is a compressor motor that drives an air conditioner, and the power conversion device 100 is a motor driving device that drives such a compressor motor.

However, the motor 200 is not limited to a compressor motor, and may be used in various application products using an AC voltage having a variable frequency, for example, an AC motor such as a refrigerator, a washing machine, an electric vehicle, a car, and a vacuum cleaner.

Meanwhile, the motor driving apparatus 100 may further include a DC-link voltage detector (B), an input voltage detector (A), an input current detector (D), and an output current detector (E).

The motor driving device 100 receives AC power from a system, converts 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 direct current-to-direct current (DC-DC) converter that operates as a power factor control (PFC) unit. In addition, such a direct current-to-direct current (DC-DC) converter may use a boost converter. In some cases, the converter 120 may be a concept including the rectifier 110. Hereinafter, the converter 120 will be described as an example using a step-up converter.

The rectifier 110 receives the single-phase AC power supply 10 and rectifies it, and outputs the rectified power to the converter 120. To this end, the rectifying unit 110 may use a full-wave rectifying circuit using a bridge diode.

In this way, the converter 120 may perform a power factor improvement operation in the process of boosting and smoothing the voltage rectified by the rectifier 110.

The converter 120 includes an inductor L1 connected to the rectifying unit 110, a switching element Q1 connected to the inductor L1, a capacitor C connected in parallel with the switching element Q1, and A diode D1 connected between the switching element Q1 and the capacitor C may be included.

The boost converter 120 is a converter capable of obtaining an output voltage higher than the input voltage, and when the switching element Q1 conducts, the diode D1 is cut off and energy is stored in the inductor L1 and stored in the capacitor C. The existing charge is discharged and an output voltage is generated at the output terminal.

In addition, when the switching element Q1 is blocked, energy stored in the inductor L1 is added and transferred to the output terminal when the switching element Q1 is turned on.

Here, the switching element 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 a 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).

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

In this way, the converter controller 130 may control the turn-on timing of the switching element Q1 in the converter 120. Accordingly, the converter control signal Sc for the turn-on timing of the switching element Q1 may be output.

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

In some cases, the converter 120 and the converter control unit 130 may be omitted. That is, the output voltage passing through the rectifier 110 may be charged in the DC-link capacitor C or the inverter 140 may be driven.

In addition, when DC power is used, such as a power conversion device used in a vehicle, the rectifier 110, the converter 120, the DC-link capacitor C, and the converter control unit 130 may be omitted. Alternatively, the DC-link capacitor C in FIGS. 1 and 2 may correspond to a battery of a vehicle.

That is, AC power for driving the compressor motor 200 may be generated by the inverter 140 using DC power supplied from the battery of the vehicle. In this case, the power conversion device 100 may be mainly an inverter 140.

The input voltage detector A may detect the input voltage Vs from the input AC power supply 10. For example, it may be located at the front end of the rectifying unit 110.

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

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

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

The DC voltage detector B detects the pulsating voltage Vdc of the DC-link capacitor C. To detect such power, a resistance element, an OP AMP, or the like may be used. The detected voltage Vdc of the DC-link capacitor C may be applied to the inverter controller 150 as a pulsed discrete signal, and the DC voltage Vdc of the DC-link capacitor C ), the inverter control signal Si may be generated.

Meanwhile, unlike the drawings, the detected DC voltage may be applied to the converter controller 130 and used to generate the converter control signal Sc.

Inverter 140 includes a plurality of inverter switching elements (Qa, Qb, Qc, Qa', Qb', Qc'), and a DC power supply (Vdc) smoothed by the on/off operation of the switching element is supplied to a predetermined frequency. It can be converted into a three-phase AC power source of, and output to the three-phase motor 200.

Specifically, the inverter 140 is a pair of upper-arm switching elements (Qa, Qb, Qc) and lower-arm switching elements (Qa', Qb', Qc') connected in series with each other, and a total of three pairs of upper and lower arm switching The elements can be connected in parallel with each other.

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

The inverter controller 150 may output an 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 a pulse width modulation (PWM) switching control signal, based on the output current (io) flowing through the motor 200 and the DC-link voltage (Vdc) at both ends of the DC-link capacitor (C). Can be generated and output. The output current io at this time may be detected from the output current detector E, and the DC-link voltage Vdc may be detected from the DC-link voltage detector B.

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

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

Specifically, the inverter control unit 150 includes a driving unit 151 that drives a plurality of inverter switching elements Qa, Qb, Qc, Qa', Qb', Qc', and a control unit that transmits a driving signal to the driving unit 151. (152) may be included.

In this case, a variable resistor unit 160 (refer to FIG. 3) may be provided between the driving unit 151 and at least one of the inverter switching elements Qa, Qb, Qc, Qa', Qb', and Qc'. In this case, a gate resistor (not shown) may be positioned between the driver 151 and other inverter switching elements Qa, Qb, Qc, Qa', Qb', and Qc'.

Alternatively, a variable resistor unit 160 may be provided between the driving unit 151 and each of the inverter switching elements Qa, Qb, Qc, Qa', Qb', and Qc'.

At this time, the control unit 152 transmits the driving signal (switching control signal) to the gate driver and at the same time, to the variable resistance unit 160 to have a different modulation resistance value according to the output current detected by the output current detection unit E A signal that changes the resistance value can be transmitted.

By modulating the driving signal applied to the gate terminals of the switching elements Qa, Qb, Qc, Qa', Qb', Qc' by the variable resistance unit 160 and its control process, energy for the frequency of the corresponding driving signal is modulated. Is dispersed so that noise can be reduced. That is, electromagnetic interference (EMI) characteristics may be improved.

This configuration and operation will be described in detail below.

3 is a block diagram showing a part of a power conversion device according to an embodiment of the present invention.

Referring to FIG. 3, a variable resistance unit 160 may be provided between a gate end of the switching element Qa and a driving unit 151 for driving the switching element Qa.

At this time, as described above, the control unit 152 may transmit a PWM control signal to the driving unit 151, and the driving unit 151 transmits a driving signal for driving the switching element Qa of each phase in response to the control signal. I can.

3 shows a state in which the variable resistance unit 160 is connected to one switching element Qa, but other switching elements, for example, other switching elements Qb, Qc, Qa', shown in FIG. The variable resistor unit 160 may also be connected to Qb' and Qc'.

In addition, as mentioned above, the variable resistor unit 160 may be connected to at least one of the other switching elements Qa, Qb, Qc, Qa', Qb', and Qc' shown in FIG. 2.

The control unit 152 transmits a signal for varying the resistance value to the variable resistance unit 160 to have a different modulation resistance value according to the output current sensed by the output current detection unit (E; see FIG. 1) independently of the control signal. I can.

In this case, the variable resistance unit 160 may be a digital variable resistance whose resistance value is adjusted according to a voltage value transmitted from the control unit 152. Accordingly, the variable resistance unit 160 may have a modulation resistance value that varies according to a voltage value received from the control unit 152.

4 is a graph showing a previous term according to an input voltage of a variable resistor of a power conversion device according to an embodiment of the present invention.

As described above, the variable resistance unit 160 may change a resistance value according to a voltage value transmitted from the control unit 152. In this case, the input voltage may have a value between 0V and 5V, for example, when the control unit 152 is implemented as a microcomputer driven with a 5V voltage, and accordingly, the resistance value has a value between 0Ω and 100Ω. I can.

In this case, a voltage value of substantially 0V to 2.5V may be used, and the resistance value of the variable resistor unit 160 used at this time may be 5Ω to 50Ω.

In addition, the modulation resistance value may increase according to the output current sensed by the output current detection unit E. That is, as the output current sensed by the output current detector E increases, the modulation resistance value may have a larger value.

In this case, the modulation resistance value may increase in proportion to the output current sensed by the output current detection unit E. For example, the control unit 152 may output a voltage value for controlling the variable resistance unit 160 in proportion to the output current sensed by the output current detection unit E. That is, the control unit 152 may increase a voltage value output to the variable resistance unit 160 in proportion to the output current sensed by the output current detection unit E.

In this way, a control voltage value output from the control unit 152 to the variable resistance unit 160 may be modulated according to the output current sensed by the output current detection unit E. In this case, the control voltage value may additionally vary from a value determined according to the output current sensed by the output current detection unit E.

That is, the control unit 152 may control the variable resistance unit 160 so that the modulation resistance value determined according to the output current sensed by the output current detection unit E varies within a predetermined range.

Specifically, the control unit 152 controls the variable resistance unit 160 so that the modulation resistance value determined according to the output current sensed by the output current detection unit E varies within a predetermined range around the thus determined modulation resistance value. I can.

This certain range may be, for example, 10% above and below the determined modulation resistance value. For example, when the modulation resistance value is determined to be 10 Ω, the control unit 152 may control the variable resistance unit 160 to vary between 9 Ω and 11 Ω, which is a value that varies by 10% from the 10 Ω. This variable period may be arbitrary.

The change in the resistance value of the variable resistance unit 160 by the control of the control unit 152 is summarized in Table 1 below.

Here, Iout denotes the output current sensed by the output current detection unit E, and Vout denotes an output voltage for controlling the variable resistance unit 160 by the controller 152. In addition, the gate on resister represents a gate resistance connected to the switching element, that is, an actual resistance value of the variable resistance unit 160.

As shown, the output voltage for controlling the variable resistance unit 160 by the control unit 152 increases in proportion to the output current sensed by the output current detection unit E, and accordingly, the gate resistance value connected to the switching element is increased. It can grow.

In addition, the variable resistance unit 160 may be controlled by the controller 152 so that the gate resistance value varies within a certain range (eg, 10% above and below). For example, when the output current sensed by the output current detection unit E is 10A, the control unit 152 may output a voltage value that varies within 10% from 0.5V to the variable resistance unit 160.

5 is a flowchart illustrating a method of controlling a power conversion device according to an embodiment of the present invention.

Hereinafter, a process of controlling the power conversion device described above will be described in detail with reference to FIGS. 1 to 5. This control process may be performed by the controller 152.

First, after the motor 200 is initially driven, an operation S100 of sensing the input voltage Vdc and the output current io of the inverter 140 may be performed. That is, the input voltage Vdc and the output current io input to the inverter 140 through the rectifier 110 and/or the converter 130 may be sensed.

Thereafter, according to an embodiment of the present invention, a PWM control signal may be output from the control unit 152 to the driving unit 151 according to the target driving speed of the corresponding motor 200 (S200).

Then, the driving unit 151 may output a driving signal for driving the switching element of the inverter 140 to the switching element.

In this way, the driving unit 151 outputs the PWM driving signal by the PWM control signal, so that the motor 200 can be driven at the target speed.

In this case, a resistance value between the switching element and the driver 151 may change according to a change in the output current io.

That is, the control unit 152 may control the variable resistance unit 160 so that the resistance value between the switching element and the driving unit 151 is modulated (S300).

The process of controlling the variable resistance unit 160 may include the following process.

That is, the control voltage of the variable resistance unit 160 may be output so that the resistance value between the switching element and the driving unit 151 is modulated according to a change in the output current io (S310).

The resistance value of the variable resistance unit 160 may be updated at any time or at a predetermined period according to the control voltage (S320).

In this case, as described above, a control voltage value for controlling the variable resistance unit 160 may be modulated according to the output current sensed by the output current detection unit E. In this case, the control voltage value may additionally vary from a value determined according to the output current sensed by the output current detection unit E.

That is, according to an embodiment of the present invention, the control unit 152 can control the variable resistance unit 160 so that the modulation resistance value determined according to the output current sensed by the output current detection unit E varies within a certain range. have.

Specifically, according to an embodiment of the present invention, in the control unit 152, the modulation resistance value determined according to the output current sensed by the output current detection unit E is variable within a certain range around the determined modulation resistance value. The resistance unit 160 can be controlled.

6 is a flow chart showing a specific process of controlling a variable resistor of the power conversion device according to an embodiment of the present invention.

Referring to FIG. 6, a process of controlling the variable resistor unit 160 of the power conversion device 100 by outputting a control voltage to the variable resistor unit 160 may include the following processes in detail.

First, a control voltage of the variable resistor unit 160 may be determined according to a change in the output current (S311).

Thereafter, the determined control voltage may be varied within a predetermined range (S312).

Then, the variable control voltage may be output to the variable resistor unit 160 (S313).

By controlling the variable resistance unit 160 through such a process, electromagnetic interference (EMI) characteristics may be improved when the switching element is driven.

7 is a signal diagram showing a driving signal of a power conversion device according to an embodiment of the present invention.

Hereinafter, an effect according to an embodiment of the present invention will be described with reference to FIG. 7.

The inverter 140 or the converter 120 as described above uses a switching element to change power.

Such an on/off operation of the switching element causes noise to be generated, which in turn adversely affects electromagnetic compatibility (EMC).

In order to reduce this noise, a filter of an inductor and a capacitor is additionally installed to limit it, and an EMC film is used, and a ground path is also manufactured. In addition to these means, an inductor may be mounted on the winding.

If such a method is applied, the noise reduction effect is improved, but the overall circuit driving efficiency decreases, occupies a large volume, and may cause an increase in manufacturing cost.

Accordingly, as in the present invention, the driving signal can be stabilized by controlling the gate resistance by controlling the slope of the rise time at which the amplitude of the signal increases during operation of the switching element by controlling the variable resistance unit 160 described above.

In FIG. 7, a dotted line represents a driving signal when the magnitude of the driving signal has a fixed resistance value (No modulation), that is, a periodic PWM driving voltage. In this case, it can be seen that noise is concentrated as shown, which may adversely affect EMC and EMI.

In FIG. 7, a dashed line represents a driving signal when the magnitude of the driving signal has a modulated resistance value, that is, when a substantially aperiodic PWM driving voltage is obtained by modulation of the resistance value.

In this case, as shown, it can be seen that noise is dispersed, and accordingly, EMC and EMI can be improved.

As described above, according to an embodiment of the present invention, it is possible to improve EMC and EMI by stabilizing the driving signal.

In addition, while improving EMC and EMI, the overall circuit driving efficiency does not decrease, the volume of the circuit does not increase, and the manufacturing cost does not increase.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are only presented specific examples to aid understanding, and are not intended to limit the scope of the present invention. In addition to the embodiments disclosed herein, it is apparent to those of ordinary skill in the art that other modified examples based on the technical idea of the present invention may be implemented.

100: power conversion device 110: rectifier
120: converter 130: converter control unit
131: converter driving unit 150: inverter control unit
151: drive unit 152: control unit
160: variable resistance unit

Claims (10)

An inverter including a plurality of switching elements to generate an AC signal for driving the motor;
A gate driver driving the plurality of switching elements;
A variable resistance part connected between the gate driver and the switching element;
An output current detection unit detecting an output current of the inverter; And
A control voltage value for varying a resistance value to the variable resistance unit so that a control signal is transmitted to the gate driver and a modulation resistance value determined to be continuously changed in proportion to the magnitude of the output current sensed by the output current detection unit It is configured to include a control unit to transmit,
The variable resistance unit is a digital variable resistance whose resistance value is adjusted according to a voltage value transmitted from the control unit,
The variable resistance part is connected to the gate terminal of each of the switch elements,
The control unit controls the variable resistance unit so that the modulation resistance value varies within a predetermined range based on the determined modulation resistance value,
The predetermined range is determined by a predetermined ratio above and below the determined modulation resistance value. delete delete delete delete The power conversion device of claim 1, wherein the control unit controls the variable resistance unit so that the modulation resistance value varies within 10% above and below the determined modulation resistance value. A compressor comprising the power conversion device of any one of claims 1 and 6.
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