KR101946373B1 - Power transforming apparatus and air conditioner including the same - Google Patents

Abstract

The present invention relates to a power transforming apparatus, and specifically, to a power transforming apparatus equipped with an input voltage detecting unit and to an air conditioner including the same. The power transforming apparatus of the present invention comprises: a rectifying unit rectifying an AC voltage inputted from an AC power source; a power factor control unit including a switching element and performing a power factor improvement operation with respect to the voltage rectified in the rectifying unit; and an input voltage sensing circuit detecting the input voltage of the AC power source by using a voltage distribution circuit which includes at least two resistors, wherein the input voltage sensing circuit is located between the AC power source and the rectifying unit.

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,

The present invention relates to a power conversion apparatus, and more particularly, to a power conversion apparatus having an input voltage detection unit 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.

Such a power conversion apparatus is generally known to include a rectifying section, a power factor control section, and an inverter.

First, the commercial voltage of the AC output from the commercial power source is rectified by the rectifying part. The rectified voltage at this rectifying part is supplied to the inverter. At this time, the inverter generates AC power for driving the motor by using the voltage outputted from the rectifying section.

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

In such a power conversion apparatus, a circuit for sensing the input AC voltage may be provided at the upstream of the rectification section. Such an input voltage detecting unit may be constituted by a differential amplifier circuit using an OP-amplifier (OP AMP).

However, the input voltage detecting unit using the OP-amplifier has an internal delay time of the OP-amplifier, and efficiency in manufacturing cost and utilization of the internal space due to the use of the OP-amplifier may decrease.

In particular, variations in the input voltage can have a significant impact on the power return device, and therefore, a method is needed to detect the input voltage without delay time and with high resolution.

SUMMARY OF THE INVENTION The present invention provides a power conversion apparatus having an input voltage sensing unit capable of sensing an input voltage without delay and at high resolution, and an air conditioner including the power conversion apparatus.

According to a first aspect of the present invention, there is provided a rectifying device comprising: a rectifying part for rectifying an AC voltage input from an AC power source; A power factor control unit that performs a power factor correcting operation on a voltage rectified by the rectifying unit and includes a switching device; And an input voltage sensing circuit disposed between the AC power source and the rectifying unit and sensing an input voltage of the AC power source using a voltage distribution circuit including at least two resistors.

Here, the voltage distribution circuit may include: a first resistor connected to the first end and the second end of the AC power source, respectively; And a second resistor coupled between each of the first resistors.

Here, the input voltage sensing circuit may further include a controller receiving an output voltage of the voltage distributing circuit and sensing an input voltage.

The control unit may be a converter control unit that controls the power factor control unit.

Further, a noise filter may be further included between the voltage distribution circuit and the control section.

In this case, the noise filter may further include a diode for preventing overvoltage.

In addition, the diode may be connected such that when a voltage exceeding the allowable input voltage of the control unit is applied to the control unit from the voltage distribution circuit, a current flows toward the bias power supply.

Here, the voltage divider circuit may output a voltage signal in the form of a full-wave rectified signal.

The total amplitude of the voltage signal in the form of the full wave rectified signal may correspond to the allowable input voltage of the control unit.

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

The present invention has the following effects.

First, a voltage decomposition circuit including a resistor for voltage distribution can be constructed, and a circuit can be constructed at a low cost.

In addition, since the OP-amplifier is not used, the internal delay time can be eliminated.

Furthermore, the offset of 2.5 V, which was present when using the OP-amplifier, can be eliminated, so that the resolution for voltage sensing can be doubled compared to using an OP-amplifier.

1 is a block diagram showing a power conversion apparatus according to an embodiment of the present invention.
2 is a circuit diagram showing a power conversion apparatus according to an embodiment of the present invention.
3 is a circuit diagram showing details of a power conversion apparatus according to an embodiment of the present invention.
FIG. 4 is a signal diagram showing a sense voltage and an input voltage of the voltage divider circuit according to an embodiment of the present invention, and FIG. 5 is a signal diagram illustrating an input voltage.
6 is a signal diagram showing a sensing voltage of a voltage distribution circuit according to an embodiment of the present invention.
7 is a circuit diagram showing the flow of current when the voltage at the first stage of the AC power source is higher than the voltage at the second stage in the power conversion apparatus according to the embodiment of the present invention.
Fig. 8 is a circuit diagram showing an equivalent circuit and a current flow of the voltage divider circuit in the case of Fig. 7;
9 is a circuit diagram showing the flow of current when the voltage of the first stage of the AC power source is lower than the voltage of the second stage in the power conversion apparatus according to the embodiment of the present invention.
10 is a circuit diagram showing an equivalent circuit and a current flow of the voltage divider circuit in the case of Fig.

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 a power conversion apparatus according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a power conversion apparatus according to an embodiment of the present invention.

1 and 2, the power conversion apparatus 100 includes a rectifier 110 for rectifying an AC power source 10, a converter 110 for controlling a power factor in a process of boosting / reducing a 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-link capacitor C between the DC-link 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 converter 120 is described as the same component as the power factor control unit.

The rectifying unit 110 receives and rectifies the AC power source 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 signal rectified by the rectifier 110.

The converter 120 includes an inductor L1 connected to the rectifying section 110, a switching element Q1 connected to the inductor L1, and a switching element Q1 connected between the switching element Q1 and the DC- And a diode D1.

The boost converter 120 can obtain an output voltage higher than the input voltage. When the switching device Q1 is turned on, the diode D1 is cut off and energy is stored in the inductor L1, and the DC-link capacitor C ) Discharges and generates an output voltage at the output terminal.

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 gate (or base) terminal of the switching element Q1, and the switching operation can be performed by the PWM signal.

The converter control unit 130 may include a gate driver for transmitting a PWM signal to a gate terminal of the switching element Q1 and a controller for transmitting a driving signal to the gate driver.

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 metal oxide semi-conductor field effect transistor (MOSFET) and a bipolar transistor. The IGBT has a small driving power and is capable of 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 controller 130 may receive the input voltage Vs and the input current Is from the input voltage detector A and the input current detector D, respectively.

Optionally, such converter 120 and converter control 130 may be omitted. That is, the output voltage through the rectifying unit 110 can be charged to the DC-link capacitor C without passing through the converter 120, or the inverter 140 can be driven.

Referring to FIG. 1, the input voltage detecting unit 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 for voltage detection. The input voltage Vs detected by the input voltage detector A may be applied to the converter controller 130 to generate the converter control signal Sc.

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 pulsating voltage Vdc of the DC-link capacitor C. For such power detection, a resistance element, OP AMP, or the like can be used. The voltage Vdc of the detected DC-link capacitor C may be applied to the inverter control unit 150 as a discrete signal in the form of a pulse, and the DC voltage Vdc of the DC-link capacitor C The inverter control signal Si can be generated.

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 is provided with a plurality of inverter switching elements Qa, Qb, Qc, Q'a, Q'b and Q'c and is connected to the on / off operation of the switching element Q1 of the converter 120 Phase AC power source with a predetermined frequency, and output the converted three-phase AC power to the three-phase motor 200.

Specifically, the inverter 140 is a pair of the upper switching elements Qa, Qb, and Qc and the lower switching elements Q'a, Q'b, and Q'c that are serially connected to each other, , And the lower switching elements may be connected in parallel with each other.

The switching elements Qa, Qb, Qc, Q'a, Q'b, and Q'c of the inverter 140 may use power transistors as in the converter 120. 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 a switching control signal of the pulse width modulation method PWM and is based on the output current io flowing through the motor 200 and the DC- link voltage Vdc across the DC- Can be generated and output. The output current io at this time can be detected from the output current detecting portion E and the DC-link voltage Vdc can be detected from the DC-link voltage detecting portion B.

The inverter control unit 150 includes a gate driver for transmitting a PWM signal to the gate of the switching elements Qa, Qb, Qc, Q'a, Q'b and Q'c included in the inverter 140 And a control unit for transmitting a driving signal to the gate driving unit.

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.

In FIG. 2, the input voltage sensing unit A is implemented as the input voltage sensing circuit 160.

The conventional input voltage sensing circuit may be constituted by a differential amplifier circuit using an OP-amplifier (OP-AMP). However, such a conventional input voltage sensing circuit has an internal delay time of the OP-amplifier, and may be inefficient in production cost and internal space utilization due to the use of the OP-amplifier.

In particular, it can be important to detect the input voltage with high resolution without delay, since the variation of the input voltage can have a significant impact on the power return device.

The input voltage sensing circuit 160 according to an embodiment of the present invention can sense the input voltage Vs of the ac power using a voltage divider circuit 161 (see Fig. 3) including at least two resistors .

In this manner, the circuit can be constituted by the voltage decomposition circuit 161 including the resistor for voltage distribution, and the internal delay time can be eliminated since the OP-amplifier is not used. It can be seen that the specification of a commonly used OP-amplifier has a delay time of about 5 μs.

In addition, since the offset of 2.5 V, which is present when using the OP-amplifier, can be eliminated, the resolution for voltage sensing can be doubled as compared with the case using the OP-amplifier. The input voltage sensing circuit 160 according to one embodiment of the present invention will be described later in detail.

3 is a circuit diagram showing details of a power conversion apparatus according to an embodiment of the present invention.

Referring to FIG. 3, the details of the above-described input voltage sensing circuit 160 and the converter 120 of the power conversion device are mainly shown.

As described above, the input voltage sensing circuit 160 is provided between the AC power source 10 and the rectifying part 110, and uses the voltage distribution circuit 161, which includes at least two resistors R1 and R2, The input voltage Vs of the power source 10 can be sensed.

The voltage divider circuit 161 includes a first resistor R1 connected to the first end a and a second end b of the ac power supply 10, And a second resistor R2 connected between the first resistor R2 and the second resistor R2.

At this time, the first end (a) of the AC power source 10 may be connected to the active line (L) and the second end (b) may be connected to the neutral line (N). This connection will be described in detail with reference to Figs. 7 and 9 below.

Here, the input voltage sensing circuit 160 may further include a controller 163 that receives the output voltage of the voltage distributing circuit 161 and senses the input voltage Vs.

2, the control unit 163 may be the same as the converter control unit 130 that controls the power factor control unit (converter) 120. For example, as shown in FIG. That is, as described above, the input voltage Vs detected by the input voltage sensing circuit 160 may be applied to the converter control unit 130 to generate the converter control signal Sc.

Hereinafter, the control unit 163 of the input voltage sensing circuit 160 will be described as an example of the same components as the converter control unit 130 that controls the power factor control unit (converter) 120. [ However, the control unit 163 of the input voltage sensing circuit 160 may be a separate component from the converter control unit 130 that controls the power factor control unit (converter) 120.

As described above, the input voltage sensing circuit 160 includes a voltage divider circuit 161 for reducing the magnitude of the input voltage Vs.

The voltage divider circuit 161 outputs the first resistor R1 and the second resistor R2 so that the magnitude of the input voltage Vs is within the allowable voltage (for example, 5V) ) Is selected.

The sensing voltage V1 of the voltage divider circuit 161 is sensed by the controller 163. At this time, the sensing voltage V1 sensed by the controller 163 is calculated by the following equation (1).

On the other hand, a noise filter 162 may further be provided between the voltage divider circuit 161 and the control unit 163. [ The noise filter 162 may be an RC filter composed of a resistor R5 and a capacitor C2.

At this time, the resistor R5 may be connected to the output side (sense voltage V1) of the voltage divider circuit 161, and the capacitor C2 may be connected in parallel with the resistor R5.

The output V1 of the voltage divider circuit 161 that has passed through the noise filter 162 can be input to the AD terminal of the controller 163. [

At this time, the noise filter 162 may further include a diode D2 for preventing overvoltage. That is, when a voltage exceeding the allowable input voltage of the control unit 163 is applied from the voltage distribution circuit 161 to the control unit 163, current can flow through the diode D2.

More specifically, the diode D2 is connected between the RC filter and the bias power source 5V. When a power source of 5V or more is applied from the voltage distribution circuit 161 to the control unit 163, a forward current is formed through the diode D2 .

As such, the diode D2 can be connected such that a current flows to the bias power supply 5V when a voltage exceeding the allowable input voltage of the control section 163 is applied from the voltage distribution circuit 161 to the control section 163.

FIG. 4 is a signal diagram showing a sensing voltage and an input voltage of a voltage divider circuit according to an embodiment of the present invention, FIG. 5 is a signal diagram showing an input voltage, and FIG. Fig. 7 is a signal diagram showing the detection voltage of the voltage divider circuit.

4, when the sensing voltage V1 is compared with the input voltage Vs, the input voltage Vs of the sinusoidal-shaped AC power supply passes through the voltage distribution circuit 161, (Sense voltage) V1 in the form of a signal.

5, the input voltage Vs is a signal in the form of an AC sine wave of 500 V, for example, and has a positive component u and a negative component d with respect to the time axis t. At this time, each positive component (u) and negative component (d) has an amplitude corresponding to 500V.

6A shows the sensing voltage when the input voltage Vs is sensed through the OP-amplifier in the conventional case, and FIG. 6B shows the sensing voltage when the voltage distribution according to the embodiment of the present invention And the sensing voltage V1 of the circuit.

In the conventional case shown in FIG. 6 (a), the sensing voltage is shifted to the positive voltage signal by the shape of the sinusoidal AC voltage. Thus, the sense voltage has an offset voltage component of 2.5V. At this time, the portion that can be used for substantially sensing the input voltage is a voltage signal of 2.5V.

6 (b), the first resistor R1 is connected to the first end (a) and the second end (b), so that the voltage division together with the second resistor R2 A voltage signal of the same type as that of full-wave rectification can be input to the control unit 163 as the sensing voltage V1.

At this time, the sensing voltage V1 according to an embodiment of the present invention has a magnitude of 5V. This voltage magnitude may be the magnitude of the voltage that can be sensed by the controller 163.

That is, the total amplitude of the voltage signal (sensing voltage V1) in the form of a full wave rectified signal may correspond to the allowable input voltage (allowable voltage) of the control unit 163.

Therefore, according to the present invention, the input voltage Vs can be detected twice in detail compared with the conventional case. This is because the larger the reduction ratio from the input voltage Vs to the sensing voltage V1, the larger the sensing error becomes.

7 is a circuit diagram showing the flow of current when the voltage at the first stage of the AC power source is higher than the voltage at the second stage in the power conversion apparatus according to the embodiment of the present invention, And a circuit diagram showing the flow of current.

9 is a circuit diagram showing the flow of current when the voltage of the first stage of the AC power source is lower than the voltage of the second stage in the power conversion apparatus according to the embodiment of the present invention, A circuit diagram showing an equivalent circuit of the distribution circuit and a flow of the current.

Referring to FIG. 7, the current flows when the voltage Va at the first end (a) of the AC power source 10 is greater than the voltage (Vb) at the second end (b). That is, a case where a current flows into the power conversion device through the active line L is shown.

At this time, the current flows to the first resistor R1 through the first stage (a), and then the first resistor (R1) and the second resistor (R2) connected to the second stage (b) And then transmitted to the control unit 163 side.

8, the current flowing through the first resistor R1 through the first stage (a) is then inversely proportional to the resistance ratio of the first resistor R1 and the second resistor R2 After the current flows, they are recombined and transmitted to the control unit 163 side.

At this time, the sensing voltage V1 can be calculated from the input voltage Vs in accordance with Equation (1) described above. This sensing voltage V1 may correspond to the odd-numbered signal of the voltage signal shown in Fig. 6 (b).

9, the current flows when the voltage Va at the first end a of the AC power source 10 is lower than the voltage Vb at the second end b. That is, a case where a current flows into the power converter through the neutral line N is shown.

At this time, the current first flows to the first resistor R1 through the second stage (b), and then the first resistor R1 and the second resistor R2 connected to the first stage (a) are connected in parallel And then transmitted to the control unit 163 side.

10, the current flowing through the first resistor R1 through the second terminal (b) is then inversely proportional to the resistance ratio of the first resistor R1 and the second resistor R2 After the current flows, they are recombined and transmitted to the control unit 163 side.

At this time, the sensing voltage V1 can be calculated from the input voltage Vs in accordance with Equation (1) described above. This sensing voltage V1 may correspond to an even-numbered signal of the voltage signal shown in Fig. 6 (b).

When the voltage Va of the first stage a is greater than the voltage Vb of the second stage b and the voltage Va of the first stage a of the ac power source 10 is higher than the voltage Vb of the second stage b, The positive sensing voltage V1 is output when the voltage Vb is lower than the voltage Vb of the step (b). Thus, as described above, the resolution at the time of sensing the input voltage can be doubled as compared with the conventional case.

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 160: input voltage sensing circuit
161: Voltage distribution circuit 162: Noise filter
163:

Claims (10)

A rectifying unit for rectifying an AC voltage input from an AC power source;
A power factor control unit that performs a power factor correcting operation on a voltage rectified by the rectifying unit and includes a switching device; And
And an input voltage sensing circuit which is disposed between the AC power supply and the rectifying unit and senses an input voltage of the AC power supply using a voltage distribution circuit including at least two resistors,
Wherein the input voltage sensing circuit comprises: a controller receiving an output voltage of the voltage divider circuit and sensing an input voltage; And
And a noise filter provided between the voltage distribution circuit and the control unit and including a RC filter and a diode for preventing overvoltage. The voltage dividing circuit according to claim 1,
A first resistor connected to the first end and the second end of the AC power source, respectively; And
And a second resistor coupled between each of the first resistors. The power conversion apparatus according to claim 1, wherein an output of the voltage distribution circuit that has passed through the noise filter is input to an AD terminal of the control section. The power conversion apparatus according to claim 1, wherein the control unit is a converter control unit that controls the power factor control unit. The apparatus as claimed in claim 1,
A resistor connected to the output side of the voltage divider circuit; And
And a capacitor connected in parallel with the resistor. The power conversion apparatus according to claim 1, wherein the diode is connected between the RC filter and a bias power supply. The power conversion apparatus according to claim 1, wherein the diode is connected such that when a voltage exceeding a permissible input voltage of the control section is applied to the control section from the voltage distribution circuit, a current flows toward the bias power supply. The power conversion apparatus according to claim 1, wherein the voltage distribution circuit outputs a voltage signal in the form of a full-wave rectification signal. The power conversion apparatus according to claim 8, wherein the total amplitude of the voltage signal in the form of the full wave rectification signal corresponds to an allowable input voltage of the control section. An air conditioner comprising the power conversion device according to any one of claims 1 to 9.

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