KR102069067B1 - Power transforming apparatus including rectifier decreasing ripple current and air conditioner including the same - Google Patents

Abstract

The present invention relates to a power converter, and more particularly, to a power converter including a ripple reduction rectifier and an air conditioner including the same. The present invention includes a rectifying unit for rectifying the AC power source and outputting a rectified current having at least two ripple current components having a phase difference from each other; A capacitor for storing the rectified current output from the rectifier; And a load unit operating by using a DC current output from the capacitor.

Description

Power converting apparatus including an ripple reduction rectifier and an air conditioner including the same {Power transforming apparatus including rectifier decreasing ripple current and air conditioner including the same}

The present invention relates to a power converter, and more particularly, to a power converter including a ripple reduction rectifier and an air conditioner including the same.

Generally, the compressor of an air conditioner uses a motor as a drive source. These motors are supplied with alternating current power from a power converter.

Such a power conversion device is generally known to include a rectifier, a power factor controller and an inverter.

First, the commercial voltage of the AC output from the commercial power supply is rectified by the rectifier. The rectified voltage is supplied to the inverter. In this case, the inverter generates AC power for driving the motor by using the voltage output from the rectifier.

The rectifier can usually use a full-wave rectifier circuit or a half-wave rectifier circuit, and through this full-wave rectifier circuit or half-wave rectifier circuit, a full-wave rectified current or a half-wave rectified current is outputted.

The output current having the ripple component output from this rectifier is usually charged in an electrolytic capacitor and delivered to the load.

However, if a ripple current flows through the electrolytic capacitor, performance may be degraded due to internal loss of the electrolytic capacitor or cause a failure of the electrolytic capacitor.

The lifetime of the electrolytic capacitor may depend on the magnitude of the ripple current, and when the size of the ripple current is increased to satisfy the life (for example, 15 years) of the electronic product equipped with the electrolytic capacitor, the size of the electrolytic capacitor Will increase, which may cause higher costs.

Therefore, there is a need for a method for preventing internal loss or failure of the electrolytic capacitor due to such a ripple current.

It is an object of the present invention to provide a power conversion device including an ripple reduction rectifier for outputting a current having a reduced ripple component and using the same in a load, and an air conditioner including the same.

As a first aspect for achieving the above technical problem, the present invention includes a rectifying unit for rectifying the AC power source and outputting a rectified current having at least two ripple current components having a phase difference from each other; A capacitor for storing the rectified current output from the rectifier; And a load unit operating by using a DC current output from the capacitor.

The rectifier may include: a first rectifier rectifying the AC power and outputting a current having a ripple current component; And a second rectifying unit rectifying the AC power and outputting a current having a ripple current component having a phase difference with an output current of the first rectifying unit.

Here, the rectifier may include a full wave rectifier circuit.

Here, the rectifying unit, the first rectifying unit; A second rectifying unit; And an inductor connected between the second rectifier and the first rectifier.

In this case, the electronic device may further include a load resistor connected to the first rectifier.

Here, the phase difference may be 90 degrees.

Here, the load unit may be an inverter for generating a three-phase alternating current.

As a second aspect for achieving the above technical problem, the present invention, the first rectifier including a full-wave rectifier circuit connected to the AC power source; A second rectifier including a full-wave rectifier circuit connected to the AC power supply in parallel; A load resistor connected to the first rectifier; An inductor connected between the second rectifier and the load resistor; And a capacitor in which currents output from the first and second rectifiers are stored.

Here, the inverter may further include an inverter operating by using a DC current output from the capacitor.

An air conditioner including a power converter having the above characteristics can be provided.

The present invention has the following effects.

First, the ripple component of the current output to the DC-link capacitor can be reduced by using the current phase difference of the resistive load and the inductor load.

In this way, it is possible to improve the reliability of components such as capacitors by reducing the ripple component of the current, thereby reducing the cost of replacement of the components.

At this time, as described above, this effect can be implemented in a relatively simple and low cost by configuring each full-wave rectifier circuit having a resistive load and an inductor load.

1 is a block diagram illustrating a power conversion apparatus according to an embodiment of the present invention.
2 is a circuit diagram illustrating 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.
4 is a waveform diagram illustrating a waveform of an output current of a rectifying unit according to an exemplary 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 invention allows for various modifications and variations, specific embodiments thereof are illustrated by way of example in the drawings and will be described in detail below. However, it is not intended to be exhaustive or to limit the invention to the precise forms disclosed, but rather the invention includes all modifications, equivalents, and alternatives consistent with the spirit of the invention as defined by the claims.

When an element such as a layer, region or substrate is referred to as being on another component "on", it will be understood that it may be directly on another 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 / or regions It will be understood that it should not be limited by these terms.

1 is a block diagram illustrating a power conversion apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the power converter 100 includes a rectifier 110 rectifying the AC power supply 10, a converter 120 for boosting / depressing a DC voltage rectified by the rectifier 110, or controlling a power factor. Converter control unit 130 for controlling 120, inverter 140 for outputting a three-phase alternating current, inverter control unit 150 for controlling inverter 140, and DC between converter 120 and inverter 140 It may include a DC-link capacitor (C).

The 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 for driving an air conditioner, and the power converter 100 will be described as an example of a motor driving device for driving such a compressor motor.

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

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

The motor drive apparatus 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 DC-DC converter operating as a power factor control (PFC) unit. In addition, such a DC-DC converter may use a boost converter.

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

As described above, the converter 120 may perform a power factor improving operation in the process of boosting and smoothing the voltage signal rectified by the rectifier 110.

In some cases, the converter 120 and the converter controller 130 may be omitted. That is, the output voltage passing through the rectifier 110 may be charged in the DC-link capacitor C or drive the inverter 140 without passing through the converter 120.

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

The input voltage detector A may include a resistor, 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 detector D may detect the input current Is from the input AC power supply 10. Specifically, it may be located in front 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. For such power supply detection, a resistive element, OP AMP, or the like can be used. The detected voltage Vdc of the DC-link capacitor C may be applied to the inverter controller 150 as a discrete signal in the form of a pulse, and may be a DC voltage Vdc of the DC-link capacitor C. Inverter control signal Si may be generated based on.

On the other hand, unlike the figure, the detected DC voltage may be applied to the converter controller 130 and used to generate the converter control signal Sc.

Inverter 140 is provided with a plurality of switching elements to convert the DC power (Vdc) transmitted through the rectifier 110 or the converter 120 by the operation of the switching element into a three-phase AC power of a predetermined frequency, three-phase motor It can output to 200.

The inverter controller 150 may output the inverter control signal Si to the inverter 140 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 which is across the DC-link capacitor C. Can be generated and output. The output current io at this time can be detected from the output current detector E, and the DC-link voltage Vdc can be detected from the DC-link voltage detector B.

The output current detector E may detect the 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 two phases by using three-phase equilibrium.

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

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

Referring to FIG. 2, the configuration of the rectifier 110 is illustrated in detail, and the configuration of the inverter and the motor described with reference to FIG. 1 is briefly illustrated as the load 140.

Here, the configuration of the converter described with reference to FIG. 1 may be omitted.

As shown in FIG. 2, the rectifier 110 may rectify the AC power supply 10 to output a rectified current having at least two ripple current components having a phase difference from each other.

The rectifier 110 rectifies the AC power supply 10 and outputs a current having a ripple current component. The rectifier 110 rectifies the AC power supply 10 and outputs a phase difference from the output current of the first rectifier 111. It may include a second rectifier 112 for outputting a current having a ripple current component having a.

In detail, a load resistor R1 is connected to the first rectifier 111, an inductor L1 is connected to the second rectifier 112, and the inductor L1 may be connected to an output side of the first rectifier 111. have. That is, the inductor L1 may be connected to the load resistor R1.

Here, the first rectifying unit 111 and the second rectifying unit 112 may include a full-wave rectifying circuit as described above. That is, the first rectifier 111 and the second rectifier 112 may use a full-wave rectifier circuit using a bridge diode.

Meanwhile, the first rectifier 111 may be regarded as including a load resistor R1, and the second rectifier 112 may be regarded as including an inductor L1. At this time, since the current flowing through the inductor L1 has a component differentiated with respect to time by Equation 1, a phase difference between the current output from the first rectifying unit 111 and the current output from the second rectifying unit 112. May be present.

Specifically, since the output current Ib of the second rectifier 112 passes through the inductor L1, the output current Ib of the second rectifier 112 may have a phase difference of 90 degrees with the output current Ia of the first rectifier 111.

Referring to FIG. 2 together, Ia represents the waveform of the current flowing through the load resistor R1, Ib represents the waveform of the current flowing through the inductor L1, and Ic represents the current Ia flowing through the load resistor R1. And the current Ib flowing through the inductor L1 are the sum of the currents at the F point.

As described above, the current Ic summed at the F point may be a smoothed current due to the large ripple component of the two output currents Ia and Ib being greatly alleviated. This will be described later in detail.

The smoothed current Ic is charged in the DC-link capacitor C, and the load 140 can operate using the power charged in the DC-link capacitor C. FIG.

Here, the load 140 that operates using the DC current output from the capacitor C may be an inverter.

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

As described above, the rectifier 110 may be connected to the converter 120. Here, the converter 120 will be described taking an example of using a boost converter.

The converter 120 is connected between the inductor L2 connected to the rectifier 110, the switching element Q1 connected to the inductor L2, and the switching element Q1 and the DC-link capacitor C. It may include a diode (D1).

The boost converter 120 is a converter capable of obtaining an output voltage higher than an input voltage. When the switching element Q1 is turned on, the diode D1 is blocked and energy is stored in the inductor L2. The DC-link capacitor C The electric charge stored in the capacitor discharges to generate an output voltage at the output terminal.

In addition, when the switching element Q1 is cut off, the energy stored in the inductor L2 is added to the output terminal when the switching element Q1 conducts.

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 controller 130 may be connected to a gate (or base) terminal of the switching element Q1 to perform a switching operation by this PWM signal.

The converter controller 130 may include a gate driver for transmitting a PWM signal to the 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 power MOSFET (metal oxide semi-conductor field effect transistor) and a bipolar transistor, and has a small driving power, and is capable of high speed switching, high breakdown voltage, and high current density.

As such, 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 turning on the switching element Q1 may be output.

To this end, 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.

The converter 120 may perform a power factor control action, and as mentioned above, the converter 120 may be omitted.

Meanwhile, the load 140 described with reference to FIG. 2 may be the inverter 140 of FIG. 3.

The inverter 140 includes a plurality of inverter switching elements Qa, Qb, Qc, Qa ', Qb', and Qc '. The inverter 140 smoothes the DC power supply Vdc smoothed by the action of the rectifier 110 at a predetermined frequency. It can be converted into a three-phase AC power source and output to the three-phase motor 200.

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

Like the converter 120, the switching elements Qa, Qb, Qc, Q'a, Q'b, and Q'c of the inverter 140 may use a power transistor, for example, an insulated gate bipolar transistor. (insulated gate bipolar mode transistor; IGBT) can be used.

4 is a waveform diagram illustrating waveforms of output currents of a rectifying unit according to an exemplary embodiment of the present invention.

In this case, Ia of FIG. 4 represents an output current through the first rectifying unit 111, Ib of FIG. 4 represents an output current through the second rectifying unit 112, and Ic of FIG. 4 represents a current waveform in which two output currents are combined. Indicates.

Hereinafter, the operation of an embodiment of the present invention will be described in detail with reference to FIGS. 2 to 4.

First, when an AC power source 10 is input, full-wave rectification is performed through the first rectifying unit 111 and the second rectifying unit 112.

The full-wave rectified voltage charges the electrolytic capacitor C (DC-link capacitor) through the load resistor R1 and the inductor L1 load, respectively.

At this time, the current Ia flowing through the load resistor R1 is expressed by Equation 1 below.

In addition, the current Ib flowing through the inductor L1 is represented by Equation 2 below.

The current Ia and the current Ib are combined into Ic at the F point, and the current Ib flowing through the inductor L1 load flows with a phase difference of 90 degrees with the voltage v (t) as shown in Equation 2.

At this time, the current Ic in which the current Ia flowing through the load resistor R1 and the current Ib flowing through the inductor L1 are combined is expressed by Equation 3 below.

That is, if the voltage v (t) has a sin waveform, the current Ic has a waveform in which a sine waveform and a cosine waveform are combined with each other, and thus, a ripple-reduced waveform may be obtained as shown in FIG. 3.

In the above process, the ripple component of the current output to the capacitor C can be reduced by using the current phase difference between the resistive load R1 and the inductor load L1.

In this way, by reducing the ripple component of the current can improve the reliability of the component such as the capacitor (C), thereby reducing the cost required for the replacement of the component.

At this time, as described above, such an effect constitutes a full-wave rectification circuit having a resistive load (R1) and an inductor load (L1), the circuit can be implemented relatively simple and at a low cost.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are merely presented specific examples to aid understanding, and are not intended to limit the scope of the present invention. It is apparent to those skilled in the art that other modifications based on the technical spirit of the present invention can be carried out in addition to the embodiments disclosed herein.

100: power converter 110: rectifier
111: first rectifier 112: second rectifier
120: converter 130: converter control unit
140: inverter, load 150: inverter control unit
200: motor

Claims (10)

A first rectifying unit rectifying the AC power and outputting a current having a ripple current component, and a second rectifying unit rectifying the AC power and outputting a current having a ripple current component having a phase difference with an output current of the first rectifying unit; And a rectifier for rectifying the AC power and outputting a rectified current having at least two ripple current components having a phase difference from each other.
A load resistor having one end connected to the first rectifier;
A first inductor connected between one end of the second rectifier and the other end of the load resistor;
A second inductor connected to a first point at which the load resistor and the inductor are joined, a second inductor connected in series to the first point, a diode connected to the second inductor, and between the second inductor and the diode and the second rectifier A converter including a switching element connected between the other ends of the converter;
A converter controller to control turn-on timing of the switching element;
A capacitor outputted from the rectifier and configured to store a current passing through the converter; And
It is configured to include a load unit that operates using a direct current output from the capacitor,
The first inductor and the switching element are connected in parallel with each other with the second inductor therebetween,
The current having a different phase while passing through the load resistor and the first inductor is combined with each other through the first point with a phase difference of 90 degrees, and stored as energy in the second inductor while reducing the ripple component of the current. Power conversion device characterized in that the. delete The power converter according to claim 1, wherein the rectifier includes a full wave rectifier circuit. delete The power converter of claim 1, further comprising a DC stage voltage detector, an input voltage detector, an input current detector, and an output current detector. delete The power converter according to claim 1, wherein the load unit is an inverter that generates a three-phase alternating current. delete delete An air conditioner comprising the power converter of any one of claims 1, 3, 5 and 7.

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