KR20200055573A - Power transforming apparatus and air conditioner including the same - Google Patents

Abstract

According to an embodiment of the present invention, provided is a power converting device which can estimate the temperature of a diode. The power converting device comprises: a rectification unit rectifying alternating current (AC) power; a converter unit converting the AC power rectified by the rectification unit into direct current (DC) power; an inverter unit converting the DC power converted by the converter unit into the AC power to output the same to a motor; a diode element provided on at least one of the rectification unit, the converter unit, and the inverter unit; a voltage detection unit connected to both ends of the diode element; and a control unit estimating the temperature of the diode based on a voltage value detected by the voltage detection unit when the diode is turned on.

Description

Power conversion device and air conditioner including the same {POWER TRANSFORMING APPARATUS AND AIR CONDITIONER INCLUDING THE SAME}

The present invention relates to a power conversion device, and more particularly, to a method for protecting a power conversion device provided in an air conditioner.

Generally, a compressor of an air conditioner uses a motor as a driving source. AC power is supplied to the motor from the power converter.

It is generally known that such a power conversion device mainly includes a rectifying view, a converter, and an inverter.

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

In some cases, a DC-DC converter may be provided between the rectifier and the inverter to improve power factor.

The above-described converter and inverter typically include a diode, and in the case of such a diode, it is common not to separately include a sensor for sensing the temperature of the diode.

Therefore, in order to prevent the phenomenon that the temperature of the diode rises excessively and causes component burnout, a design margin of the power conversion device is set. That is, in the process of operating the power converter, the design characteristics of the power converter are limited so that the temperature of the diode does not reach the limit temperature.

As described above, the power conversion device designed under limited conditions has a problem in that it is difficult to realize optimal operation efficiency.

On the other hand, adding a separate temperature sensor to sense the temperature of the diode has a problem of increasing the production price.

In this regard, Korean Patent Publication No. 10-2017-0104735 (published date, 2017.09.18.) Discloses a method for estimating the temperature of an insulated gate bipolar transistor (IGBT).

However, in Korean Patent Publication No. 10-2017-0104735, an embodiment for sensing the temperature of a diode is not disclosed, so the above-described problem cannot be solved.

The present invention is to provide a power conversion device capable of estimating the temperature of a diode provided in a converter or inverter and an air conditioner including the same.

In addition, the technical problem of the present invention, without adding a separate temperature sensor, to provide a power conversion device capable of measuring the temperature of the diode provided in the power conversion device and an air conditioner including the same.

In addition, the technical problem of the present invention, by measuring the actual temperature of the diode, to provide a power conversion device that maximizes the operation efficiency and an air conditioner including the same.

In addition, the technical problem of the present invention is to provide a power conversion device and an air conditioner including the same, which can prevent a failure due to overheating of the diode.

In addition, the technical problem of the present invention is to provide a power converter and an air conditioner including the same, which minimizes design margin and realizes optimum performance.

In order to solve the above problems, the power conversion apparatus according to an embodiment of the present invention includes a rectifying unit for rectifying AC power, a converter unit for converting AC power rectified by the rectifying unit into DC power, and the converter unit. A diode element provided in at least one of an inverter part, the rectifying part, a converter part and an inverter part that converts the converted DC power into AC power and outputs it to a motor, a voltage sensing part connected to both ends of the diode device and the diode are turned on. When in the state, it characterized in that it comprises a control unit for estimating the temperature of the diode, based on the voltage value detected by the voltage sensing unit.

In one embodiment, the voltage sensing unit is characterized by consisting of a differential amplifier.

In one embodiment, the voltage sensing unit senses a forward voltage value of the diode when the diode is turned on, and breaks down the voltage of the diode when the diode is turned off. ) It is characterized by sensing the value.

In one embodiment, the control unit is characterized by comparing the voltage value sensed by the voltage detection unit with a preset temperature table, and calculating the temperature of the diode based on the comparison result.

In one embodiment, the temperature table is characterized in that it is variably set according to the characteristics of the diode element to which the voltage sensor is connected.

In one embodiment, the control unit is characterized in that when a plurality of diode elements and the corresponding voltage sensing unit provided in the power conversion device, a plurality of temperature tables corresponding to each voltage sensing unit is set.

In one embodiment, if the control unit receives a voltage value sensed by any one of the plurality of voltage sensing units, the controller selects one of the plurality of temperature tables corresponding to the voltage sensing unit transmitting the voltage values. And comparing the selected temperature table with the received voltage value to calculate the temperature of the diode element corresponding to the voltage sensing unit that has transmitted the voltage value.

In one embodiment, when the calculated temperature exceeds a preset limit temperature, the control unit is characterized in that the operation of the power conversion device is stopped.

In one embodiment, the rectifying unit is composed of a full-bridge (Full-Bridge) circuit, the diode element is characterized in that any one of a plurality of diode elements included in the full-bridge circuit.

In one embodiment, further comprising a DC link (DC Link) capacitor for storing the DC power converted by the converter unit, the diode element is characterized in that disposed between the converter unit and the DC link capacitor .

The effects of the power conversion device and the air conditioner including the same will be described as follows.

According to at least one of the embodiments of the present invention, by sensing the PWM signal applied to the converter driving unit to determine the congestion of the converter control unit and cut off the output of the driving signal of the converter driving unit, the burnout of the switching element of the converter is efficiently performed. Can be prevented.

In addition, according to the present invention, when the determination signal corresponding to the congestion of the converter control unit is high, during the time when the high signal is applied to the converter driving unit, the driving signal output of the converter driving unit is continuously blocked, thereby maximizing the life of the converter switching element. Can be extended.

Further scope of applicability of the present invention will become apparent from the following detailed description. However, various changes and modifications within the spirit and scope of the present invention may be clearly understood by those skilled in the art, and thus, it should be understood that specific embodiments such as detailed description and preferred embodiments of the present invention are given as examples only.

1 is a block diagram for explaining a power conversion apparatus according to the present invention.
2 is a circuit diagram for explaining a power conversion apparatus according to the present invention.
3 is a circuit diagram showing an embodiment of a power conversion apparatus according to the present invention.

Hereinafter, exemplary embodiments disclosed herein will be described in detail with reference to the accompanying drawings, but the same or similar elements are assigned the same reference numbers regardless of the reference numerals, and overlapping descriptions thereof will be omitted. The suffixes "modules" and "parts" for components used in the following description are given or mixed only considering the ease of writing the specification, and do not have meanings or roles distinguished from each other in themselves. In addition, in describing the embodiments disclosed in this specification, detailed descriptions of related well-known technologies are omitted when it is determined that they may obscure the gist of the embodiments disclosed herein. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed in the specification is not limited by the accompanying drawings, and all modifications included in the spirit and technical scope of the present invention , It should be understood to include equivalents or substitutes.

1 is a block diagram showing an example of a power conversion device to which the present invention can be applied, and FIG. 2 is a circuit diagram showing an example of a power conversion device to which the present invention can be applied.

Referring to FIGS. 1 and 2, the power conversion device 100 includes a rectifying unit 110 rectifying the AC power supply 10, a converter unit controlling the power factor of the DC voltage rectified by the rectifying unit 110. 120), a converter control unit 130 for controlling the converter unit 120, an inverter unit 140 for outputting a three-phase alternating current, an inverter control unit 150 for controlling the inverter unit 140, and a converter unit 120 And a DC-link capacitor C between the and the inverter unit 140.

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

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

Meanwhile, the power conversion apparatus 100 may further include a DC terminal voltage detector B, an input voltage detector A, an input current detector D, and an output current detector E.

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

The converter unit 120 converts the input AC power supply 10 to a DC power supply. The converter unit 120 may use a DC-DC converter that operates as a power factor control unit (power factor control (PFC) unit). In addition, the DC-DC converter may use a boost converter. In some cases, the converter unit 120 may be a concept including the rectifying unit 110. Hereinafter, the converter unit 120 will be described as an example using a boost converter.

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

As such, the converter unit 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 rectifier 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 DC-link capacitor C.

The step-up converter 120 is a converter capable of obtaining an output voltage higher than the input voltage. When the switching element Q1 is conducted, the diode D1 is cut off and energy is stored in the inductor L1, and the DC-link capacitor ( As the charge stored in C) discharges, an output voltage is generated at the output terminal.

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

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 a base (or gate) terminal of the switching element Q1, so that the PWM signal can perform a switching operation.

The converter controller 130 may be configured to 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).

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

As such, the converter control unit 130 may control the turn-on timing of the switching element Q1 in the converter unit 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 the input voltage Vs and the input current Is from the input voltage detection unit A and the input current detection unit D, respectively.

In some cases, the converter unit 120 and the converter control unit 130 may be omitted. That is, the output voltage that has passed through the rectifying unit 110 may be charged in the DC-link capacitor C or drive the inverter unit 140 without going through the converter unit 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 at the front end of the rectifier 110.

The input voltage detector A may include a resistance element, an OP AMP, and 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 control unit 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 rectifier 110.

The input current detector D may include a current sensor, a current transformer (CT), and a shunt resistor 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 control unit 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 detecting the power supply, a resistance element, OP AMP, or the like can be used. The detected voltage (Vdc) of the DC-link capacitor (C), as a discrete signal (discrete signal) in the form of a pulse, can be applied to the inverter control unit 150, DC voltage (Vdc) of the DC-link capacitor (C) ) May generate an inverter control signal (Si).

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

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

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

Similar to the converter 120, the switching elements of the inverter (Qa, Qb, Qc, Qa ', Qb', Qc ') can use a power transistor, for example, an insulated gate bipolar transistor (insulated gate bipolar mode) transistor; IGBT).

The inverter controller 150 may output an inverter control signal Si to the inverter unit 140 to control the switching operation of the inverter unit 140. The inverter control signal Si is a pulse width modulation (PWM) switching control signal, based on an output current (io) flowing through the motor 200 and a DC-link voltage (Vdc) that is both ends of the DC-link capacitor (C). Can be generated and output. At this time, the output current io 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 inverter control unit 150 is a gate driver (151; FIG. 151) for transmitting a PWM signal to the gate terminal of the switching elements (Qa, Qb, Qc, Qa ', Qb', Qc ') included in the inverter unit 140. 4) and a control unit 152 (see FIG. 4) for transmitting a driving signal to the gate driving unit 151.

The output current detection unit E can detect the output current io flowing between the inverter unit 140 and the motor 200. That is, the current flowing through the motor 200 is detected. The output current detector E can 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 balance.

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

3 shows an embodiment of a power conversion device according to the present invention.

The power conversion apparatus 100 according to an embodiment of the present invention includes a rectifying unit 110 for rectifying AC power, a converter unit 120 for converting AC power rectified by the rectifying unit into DC power, and the converter unit It may include an inverter unit 140 that converts the converted DC power to AC power and outputs it to the motor.

In particular, the power conversion device 100 shown in FIG. 3 includes a diode element provided in at least one of a rectifying unit, a converter unit and an inverter unit, and voltage sensing units 310 and 320 connected to both ends of the diode element. Can be.

In addition, when the diode is turned on, the controller 130 may estimate the temperature of the diode based on the voltage value sensed by the voltage detectors 310 and 320.

In one embodiment, the voltage sensing units 310 and 320 may be configured as differential amplifiers.

For example, the voltage sensing unit configured as a differential amplifier may sense a forward voltage applied to the diode when the diode is turned on. In addition, the voltage sensing unit configured as a differential amplifier may sense a breakdown voltage applied to the diode when the diode is turned off.

Specifically, the breakdown voltage is 5V, and the forward voltage may be formed smaller than the breakdown voltage.

In one embodiment, the control unit 130 may compare the voltage value sensed by the voltage detection unit with a preset temperature table, and calculate the temperature of the diode based on the comparison result.

In one embodiment, the temperature table may be variably set according to the characteristics of the diode element to which the voltage sensor is connected.

That is, the controller 130 may calculate the temperature of the diode using a temperature table corresponding to the characteristics of the diode, which is the object of temperature sensing.

Information including the temperature table is stored in a memory (not shown) provided in the control unit 130 and may be changed or updated by a user. The memory may store a plurality of temperature tables, and the controller 130 may calculate the temperature of the diode by using any one of the plurality of temperature tables according to the characteristics of the diode to be sensed.

In one embodiment, the control unit 130 may set a plurality of temperature tables corresponding to each voltage sensing unit when a plurality of diode elements and corresponding voltage sensing units are provided in the power conversion device.

In one embodiment, if the control unit 130 receives a voltage value sensed by any one of the plurality of voltage detection units, which of the plurality of temperature tables corresponds to the voltage detection unit that transmits the voltage value By selecting one, and comparing the received voltage value with the selected temperature table, it is possible to calculate the temperature of the diode element corresponding to the voltage sensing unit transmitting the voltage value.

In one embodiment, when the calculated temperature exceeds a preset limit temperature, the control unit 130 may stop the operation of the power conversion device.

In one embodiment, the rectifying unit is composed of a full-bridge (Full-Bridge) circuit, the diode element is characterized in that any one of a plurality of diode elements included in the full-bridge circuit.

In one embodiment, further comprising a DC link (DC Link) capacitor for storing the DC power converted by the converter unit, the diode element is characterized in that disposed between the converter unit and the DC link capacitor .

Features, structures, effects, etc. described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, features, structures, effects, and the like exemplified in each embodiment may be combined or modified for other embodiments by a person having ordinary knowledge in the field to which the embodiments belong. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

Claims (10)

A rectifying unit rectifying AC power;
A converter unit converting AC power rectified by the rectifying unit into DC power;
An inverter unit that converts DC power converted by the converter unit into AC power and outputs it to a motor;
A diode element provided in at least one of the rectifier, converter, and inverter;
A voltage sensing unit connected to both ends of the diode element; And
And a control unit estimating the temperature of the diode based on a voltage value sensed by the voltage sensing unit when the diode is turned on. According to claim 1,
The voltage sensing unit is a power conversion device, characterized in that consisting of a differential amplifier. According to claim 2,
The voltage sensing unit,
When the diode is turned on, detects a forward voltage value of the diode,
When the diode is turned off, the power conversion device, characterized in that for detecting the breakdown voltage (Breakdown Voltage) value of the diode. According to claim 3,
The control unit,
Power conversion device, characterized in that for comparing the voltage value sensed by the voltage detection unit and a preset temperature table, and calculating the temperature of the diode based on the comparison result. The method of claim 4,
The temperature table, the power conversion device characterized in that it is variably set according to the characteristics of the diode element to which the voltage sensor is connected. The method of claim 5,
The control unit,
When a plurality of diode elements and corresponding voltage detection units are provided in the power conversion device, a plurality of temperature tables corresponding to each voltage detection unit is set. The method of claim 6,
The control unit,
When receiving the voltage value sensed by any one of the plurality of voltage sensing units, select one of the plurality of temperature tables corresponding to the voltage sensing unit transmitting the voltage value,
And comparing the selected temperature table and the received voltage value, and calculating the temperature of the diode element corresponding to the voltage sensing unit that transmitted the voltage value. The method of claim 4,
The control unit,
When the calculated temperature exceeds a preset limit temperature, the power conversion device, characterized in that to stop the operation of the power conversion device. According to claim 1,
The rectifying unit is composed of a full-bridge (Full-Bridge) circuit,
The diode element is a power conversion device, characterized in that any one of a plurality of diode elements included in the full bridge circuit. According to claim 1,
Further comprising a DC link (DC Link) capacitor for storing the DC power converted by the converter unit,
The diode element is a power conversion device, characterized in that disposed between the converter and the DC link capacitor.

Images