KR20090113625A - Motor controller - Google Patents

Abstract

PURPOSE: A control device of a motor is provided to protect capacitors and other circuit elements by blocking the power supply when the voltage applied to the capacitors is abnormal. CONSTITUTION: A control device of a motor includes a converter(310), an inverter(320), capacitors(C1,C2), a voltage sensor(315), and a controller(330). The converter converts the commercial AC power to the DC power. The inverter has a plurality of switching elements and converts the DC power to the AC power with a preset frequency through the switching operation. The capacitors are arranged between the converter and the inverter to smooth the DC power. The voltage sensor senses the voltage applied to the capacitors. The controller blocks the power of the inverter when the sensed voltage by the voltage sensor is blocked.

Description

Motor controller

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control apparatus, and relates to a motor control apparatus capable of preventing burnout due to voltage imbalance of a plurality of capacitors disposed between a converter and an inverter.

The motor controller is a device for converting an AC power source into a DC power source and converting the DC power source into an AC power source to drive a three-phase motor, and is used in various fields throughout the industry. For example, it is used in an air conditioner including a washing machine, a refrigerator and an air conditioner, an elevator, a car, and the like.

1 is a circuit diagram showing a conventional motor controller.

Referring to the drawings, the conventional motor control apparatus 100 converts commercial AC power into DC power using the converter 110, and smoothes and stores the voltage rectified by the plurality of capacitors Ca and Cb. do. The rectified voltage is converted into a predetermined AC power through the inverter 120 and used to drive the electric motor 150.

The use of a plurality of capacitors Ca and Cb between the converter 110 and the inverter 120 is used to store a high voltage rectified voltage. As shown in the drawing, two capacitors Ca and Cb may be connected in series. In this case, when the electrical characteristics of the two capacitors are not the same, different rectified voltages are distributed to the capacitors Ca and Cb according to the voltage distribution principle. Due to the high voltage rectified voltage, a motor controller including a capacitor element There was a problem that the circuit elements in the circuit do not withstand the breakdown voltage is burned out.

It is an object of the present invention to provide an electric motor control device capable of preventing burnout due to voltage imbalance of a plurality of capacitors disposed between a converter and an inverter.

The motor control apparatus according to the embodiment of the present invention for solving the above-mentioned problems and other problems is provided with a converter for converting a commercial AC power source to a direct current power source, a plurality of switching elements, the switching operation by receiving a direct current power source An inverter for converting into an AC power having a predetermined frequency and supplying it to a three-phase electric motor, a plurality of capacitors disposed between the converter and the inverter and smoothing the DC power, a voltage sensing unit for sensing a voltage applied to the capacitor, It includes a control unit for determining whether or not the voltage abnormality, and cut off the power when determining the abnormality.

As described above, the motor control apparatus according to the embodiment of the present invention detects a voltage applied to a plurality of capacitors disposed between the converter and the inverter to determine whether there is an abnormality, and cuts off the power supply when the abnormality is determined, thereby preventing the It is possible to prevent the capacitor from being burned out due to voltage imbalance, and also to protect other circuit elements in the motor controller. As a result, the stability of the motor controller is improved.

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

2 is a schematic diagram of an air conditioner according to the present invention.

An air conditioner is a device that is disposed in a room, a living room, an office, or a business store to adjust a temperature, humidity, cleanliness, and airflow of an air to maintain a comfortable indoor environment.

Referring to the drawings, the air conditioner 200 is largely divided into an indoor unit (I) and an outdoor unit (O).

The outdoor unit O includes a compressor 202 that serves to compress the refrigerant, a compressor electric motor 202b that drives the compressor, an outdoor heat exchanger 204 that serves to radiate the compressed refrigerant, and an outdoor heat exchanger. An outdoor blower 205, which is disposed on one side of the machine 204 and includes an outdoor fan 205a for promoting heat dissipation of the refrigerant and an electric motor 205b for rotating the outdoor fan 205a, and an expansion mechanism for expanding the condensed refrigerant. 206, the cooling / heating switching valve 210 for changing the flow path of the compressed refrigerant, the accumulator 203 for temporarily storing the gasified refrigerant to remove moisture and foreign matter, and then supplying a refrigerant having a constant pressure to the compressor. It includes.

The indoor unit I is an indoor heat exchanger 208 disposed indoors to perform a cooling / heating function, and an indoor fan 209a and an indoor fan disposed on one side of the indoor heat exchanger 208 to promote heat dissipation of the refrigerant. And an indoor blower 209 made of an electric motor 209b for rotating the 209a.

At least one indoor side heat exchanger 208 may be installed. The compressor 202 may be at least one of an inverter compressor and a constant speed compressor.

In addition, the air conditioner 200 may be configured as a cooler for cooling the room, or may be configured as a heat pump for cooling or heating the room.

On the other hand, the motor in the motor control apparatus according to an embodiment of the present invention may be each of the electric motors (202b, 205b, 209b) to operate the outdoor fan, compressor or indoor fan, shown in the figure.

3 is a circuit diagram illustrating a motor control apparatus according to an embodiment of the present invention.

Referring to the drawings, the motor control apparatus 300 according to an embodiment of the present invention, the converter 310, the inverter 320, a plurality of capacitors (C1, C2), the voltage sensing unit 315, And a controller 330. In addition, the motor control apparatus 300 according to an embodiment of the present invention, the electromagnetic contactor 305, the reactor (La), the input current detector (A), the dc terminal voltage detector (D), the output current detector (E) Or the like.

The converter 310 receives commercial AC power and converts it into DC power. To this end, the converter 310 may include a plurality of diode elements as shown in the figure. In the drawing, a plurality of diode elements are included to output a full-wave rectified DC power supply.

Meanwhile, although the three-phase AC power is illustrated as a commercial AC power in the drawing, it is possible to use a single-phase AC power without being limited thereto, and the configuration of the converter 310 is also changed.

A plurality of capacitors are disposed at both ends (between a-b) of the dc terminal, which is the output terminal of the converter 310. Some or all of the plurality of capacitors may be disposed at both ends of the dc terminal (between a-b terminals) in series with each other.

In the drawing, the first capacitor C1 and the second capacitor C2 are connected in series with each other across the dc terminal. The plurality of capacitors C1 and C2 distribute and store the DC power rectified by the converter 310.

The voltage detector 315 detects voltages applied to the plurality of capacitors C1 and C2. For example, the voltage detector 315 may include a resistor. In the drawing, the first resistor R1 and the second resistor R2 are connected in parallel to each of the capacitor C1 and the second capacitor C2 connected in series with each other. Accordingly, the voltage detector 315 may detect voltages Vde1 and Vde2 distributed at both ends of the plurality of capacitors C1 and C2 connected in series with each other. The sensed voltages Vde1 and Vde2 are input to the controller 330.

The controller 330 determines whether there is an abnormality of the sensed voltages Vde1 and Vde2, and cuts off the power when the abnormality is determined. In particular, the supply of commercial AC power can be cut off. The abnormality determination may be performed by comparing the voltage imbalance between the detected voltages Vde1 and Vde2 or by comparing the detected voltages Vde1 and Vde2 with reference values. That is, when the difference between the sensed voltages Vde1 and Vde2 is greater than or equal to the first predetermined value, or when the sensed voltages Vde1 and Vde2 are greater than or equal to the second predetermined value and greater than or equal to the third predetermined value, respectively, the controller 330 may be abnormal. You can judge.

The controller 330 may output a control signal Sa for turning off the magnetic contactor 305 when the abnormality is determined. As described above, in the case where the capacitors are distributed at both ends of the capacitors C1 and C2 of several hundred volts (V), the presence or absence of an abnormality can be easily determined, and various other circuits including the capacitors C1 and C2 are provided. The device can be protected.

The controller 330 may control the operation of the inverter 320. This will be described later with reference to FIG. 5.

Reactor La is disposed in connection with converter 310 to remove harmonic currents. In the drawings, the converter 310 is disposed between the capacitors C1 and C2, but the present invention is not limited thereto, and may be disposed between the electromagnetic contactor 305 and the converter 310.

The reactor La may correct the power factor of the AC power supply, limit the harmonic current by the commercial AC power supply, and limit the noise component of the input current i _i .

The magnetic contactor 305 is connected between the commercial AC power supply and the converter 310, and transmits the commercial AC power supply to the converter 310. When the commercial AC power source is three-phase as shown in the figure, it is possible to connect the magnetic contactor 305 to at least one of three-phase (R phase, S phase, T phase). As described above, the magnetic contactor 305 is turned off when the abnormality of the controller 330 is determined.

On the other hand, although not shown in the drawings, the motor control device 300 of FIG. 3 may further include a relay element (not shown).

The relay device (not shown) may be connected between any one of three phases (R phase, S phase, T phase) and the plurality of capacitors C1 and C2 when the commercial AC power source is three phase as shown in the figure.

This relay element (not shown) is turned on during the initial operation of the motor control device 300, and serves to store the initial voltage at either end of the plurality of capacitors, for example, the second capacitor (C2). do.

After the turn-on of the relay element (not shown), when the electromagnetic contactor 305 is turned on, commercial AC power is transferred to the converter 310, whereby a plurality of capacitors, i.e., both ends of the dc terminal (ab stage) are provided. In rectified DC power is stored.

Thereafter, the relay element (not shown) is turned off.

During the operation, when the magnetic contactor 203 is turned on while the relay element 202 is turned on, the commercial AC power is divided into two paths and stored in the plurality of capacitors C1 and C2, respectively. As a result, the inrush current is prevented.

As described above, the DC power stored in the plurality of capacitors C1 and C2 is applied to the inverter 320.

The inverter 320 includes a plurality of switching elements and a plurality of diode elements, and converts the DC power smoothed by the on / off operation of the switching element into three-phase AC power of a predetermined frequency and outputs the same.

Specifically, the upper arm switching element and the lower arm switching element connected in series to each other is a pair, a total of three pairs of upper and lower arm switching elements are connected in parallel to each other. Each switching element is connected in anti-parallel diode elements.

When the inverter switching control signal Sic is input to the gate terminal of each switching element in the inverter 320, each switching element performs a switching operation. As a result, a three-phase AC power supply having a predetermined frequency is output.

Three-phase AC power output from the inverter 320 is applied to each phase of the three-phase electric motor 350. Here, the three-phase electric motor 350 is provided with a stator and a rotor. Each phase AC power of a predetermined frequency is applied to a coil of each stator so that the rotor rotates. The three-phase motor 350 may be of various forms, such as a BLDC motor, a synRM motor.

Meanwhile, referring to FIG. 2, the three-phase electric motor 350 may be classified according to the functions of the three-phase electric motor 350, and may be a compressor electric motor 202b used in a compressor of an air conditioner, or a fan electric motor 205b and 209b for driving a fan. have.

On the other hand, the input current detector A detects an input current i _i from a commercial AC power supply. The input current detector A may be located anywhere between the commercial AC power supply and the converter 310, but the input current detector A is located between the commercial AC power supply and the magnetic contactor 305. For input current detection, a current sensor, current transformer (CT), shunt resistor, or the like can be used. The detected input current i _i may be input to the controller 330 for a circuit protection operation.

The dc terminal voltage detector D detects a dc terminal voltage Vdc, which is an output terminal of the converter 310. As the dc stage voltage detector D, a resistor or the like may be used between both ends of the dc stage. The detected dc terminal voltage Vdc may be input to the controller 330 for a circuit protection operation.

The output current detector E detects the output current i _o of the inverter output stage, that is, the current applied to the motor 350. The output current detector E may be located between the inverter 320 and the motor 350, and a current sensor, a current transformer (CT), a shunt resistor, or the like may be used for current detection. In addition, the output current detector E may be a current sensor located inside the motor 350. In addition, the output current detector E may be a shunt resistor having one end connected to three lower arm switching elements of the inverter. The detected output current i _o may be input to the controller 330 for generating and protecting the inverter switching control signal Sic.

4 is a circuit diagram illustrating a motor control apparatus according to an embodiment of the present invention.

Referring to the drawings, the motor control apparatus 400 of FIG. 4 is almost similar to the motor control apparatus 300 of FIG. The converter 410 is different in that it includes a plurality of switching elements and diode elements, and other magnetic contactors 405, converter 410, and inverter 420, a plurality of capacitors (C1, C2), voltage sensing The operations of the unit 415, the controller 430, the reactor La, the input current detector A, the dc terminal voltage detector D, and the output current detector E are the same as or similar to those of FIG. 3. Hereinafter, a description will be given of the difference from FIG. 3.

The converter 410 includes a plurality of switching elements and a plurality of diode elements, and converts a commercial AC power source into a DC power source by an on / off operation of the switching element.

When the commercial AC power source is a three-phase AC power source as shown in the drawing, similar to the inverter 420, the upper arm switching element and the lower arm switching element are paired, and a total of three pairs of the upper and lower arm switching elements are connected in parallel with each other. Diode elements may be connected in anti-parallel to each switching element.

When the magnetic contactor 305 in the drawing is in the on state, commercial AC power is transmitted to the converter 210, and when the converter switching control signal Scc is input to the gate terminal of each switching element in the converter 410, The switching element performs a switching operation. As a result, commercial AC power is converted into DC power and output.

The DC power output from the converter 410 is smoothed and stored in the plurality of capacitors C1 and C2 between the dc terminals a and b, respectively.

Meanwhile, as the converter 410 includes a plurality of switch elements, the reactor La of FIG. 4 may further perform the step-up operation as well as the operation described with reference to FIG. 3. In detail, the AC power is stored in the reactor La and supplied to the converter 410 by the on / off operation of the plurality of switches provided in the converter 410, thereby performing a boosting operation.

On the other hand, the input current i _i detected by the input current detection unit A and the dc end voltage Vdc detected by the dc end voltage detection unit D are connected to the converter switching control signal Scc in addition to the above-described protection operation. It may be input to the controller 430 to generate.

The controller 430 may control at least one operation of the converter 410 and the inverter 420. This will be described later with reference to FIGS. 5 and 6.

5 is a simplified block diagram of the inside of the controller of FIG. 3.

The controller 330 of FIG. 3 includes an estimator 405, a current command generator 410, a voltage command generator 420, and a switching control signal output unit 430.

The estimator 405 estimates the rotor speed v of the motor based on the detected output current i _o . The estimator 405 may estimate the position of the rotor in addition to the speed of the rotor.

The current command generator 410 generates a current command value (i ^* _d , i ^* _q ) based on the estimated speed v and the speed command value v ^* . That is, the current command generator 410 estimates the current command value. velocity (v) and the speed command value (v ^*) the current command value _{^{((i * d, i *}} q ) PI controller (not shown) and a current command value _{^{((i * d, i *}} q to generate) on the basis of the respective A current command limiter (not shown) may be included to limit the level so as not to exceed a predetermined value.

The voltage command generation unit 420 generates a voltage command value v ^* _d , v ^* _q based on the current command value (i ^* _d , i ^* _q ) and the detected current i _o . 420 current command value _{^{(i * d, i * q}} ) and the detected current (i _o) and the voltage command value based on a _{^{(v * d, v * q}} ) ( not shown) PI controller to generate and voltage command value ( v ^* _d , v ^* _q ) may each include a voltage command limiting unit (not shown) for limiting the level so as not to exceed a predetermined value.

The switching control signal output unit 430 generates an inverter switching control signal Sic, which is a PWM signal, based on the voltage command values v ^* _d and v ^* _q and outputs the same to the inverter.

6 is a simplified block diagram of the inside of the controller of FIG. 4.

The control unit 430 includes a current command generation unit 610, a voltage command generation unit 620, and a switching control signal output unit 630.

The current command generator 610 generates a current command value I ^* based on the detected dc terminal voltage Vdc and the dc voltage command value V ^* dc. That is, the current command generation unit 610 generates a current command value I ^* based on the detected dc terminal voltage Vdc and the dc voltage command value V ^* dc and the PI controller (not shown) and the current command value I ^* ) May include a current command limiter (not shown) to limit the level so as not to exceed a predetermined value. Meanwhile, the current command value I ^* may be the magnitude of the current command.

The voltage command generation unit 620 generates the voltage command value V ^* based on the current command value I ^* and the detected input current i _i . That is, the voltage command generation unit 620 generates a PI command value V ^* based on the current command value I ^* and the detected input current i _i and the voltage command value V ^* . May include a voltage command limiter (not shown) for limiting the level so as not to exceed a predetermined value.

The switching control signal output unit 630 generates a switching control signal Scc, which is a PWM signal, based on the voltage command value V ^* , and outputs the converted control signal Scc.

Meanwhile, the controller 330 of FIG. 3 may include all of the components 505, 510, 520, 530 of the controller 330 of FIG. 5, and the components 610, 620, 630 of the controller 430 of FIG. 6.

7 is a circuit diagram illustrating a motor control apparatus according to an embodiment of the present invention.

Referring to the drawings, the motor control apparatus 700 of FIG. 7 is almost similar to the motor control apparatus 300 of FIG. 3. Although the electromagnetic contactor 305 of FIG. 3 is not provided, other converters 710 and an inverter 720, a plurality of capacitors C1 and C2, a voltage detector 715, a controller 730, and a reactor La ), The operations of the input current detector A, the dc terminal voltage detector D, and the output current detector E are the same as or similar to those of FIG. 3. Hereinafter, a description will be given of the difference from FIG. 3.

The controller 730 determines whether there is an abnormality of the voltages Vde1 and Vde2 detected by the voltage detector 715, and cuts off the power when the abnormality is determined. In particular, the power of the inverter 720 may be cut off. The power supply of the inverter 720 may mean to cut off power applied to the gate terminal of the inverter switching element.

The abnormality determination may be performed by comparing the voltage imbalance between the detected voltages Vde1 and Vde2 or by comparing the detected voltages Vde1 and Vde2 with reference values. That is, when the difference between the sensed voltages Vde1 and Vde2 is greater than or equal to the first predetermined value, or when the sensed voltages Vde1 and Vde2 are greater than or equal to the second predetermined value and greater than or equal to the third predetermined value, respectively, the controller 730 may be abnormal. You can judge.

The controller 730 may output a control signal Sa for turning off the operation of the inverter 710 when the abnormality is determined. As described above, in the case where the capacitors are distributed at both ends of the capacitors C1 and C2 of several hundred volts (V), the presence or absence of abnormality can be easily determined, and various other circuit elements including the capacitors C1 and C2 may be used. You can protect it.

The controller 730 may further control the operation of the inverter 720. This is the same as the description of FIG. 5.

8 is a circuit diagram illustrating a motor control apparatus according to an embodiment of the present invention.

Referring to the drawings, the motor controller 800 of FIG. 8 is almost similar to the motor controller 400 of FIG. Although not provided with the magnetic contactor 405 of FIG. 4, other converters 810, an inverter 820, a plurality of capacitors C1 and C2, a voltage detector 815, a controller 830, and a reactor La ), The operations of the input current detector A, the dc terminal voltage detector D, and the output current detector E are the same as or similar to those of FIG. 4. The following description will focus on the differences from FIG. 4.

The controller 830 determines whether there is an abnormality of the voltages Vde1 and Vde2 detected by the voltage detector 815, and cuts off the power when the abnormality is determined. In particular, the power of the converter 810 may be cut off. The power supply of the converter 810 may mean to cut off power applied to the gate terminal of the converter switching element.

The abnormality determination may be performed by comparing the voltage imbalance between the detected voltages Vde1 and Vde2 or by comparing the detected voltages Vde1 and Vde2 with reference values. That is, when the difference between the sensed voltages Vde1 and Vde2 is greater than or equal to the first predetermined value, or when the sensed voltages Vde1 and Vde2 are greater than or equal to the second predetermined value and greater than or equal to the third predetermined value, respectively, the controller 830 may be abnormal. You can judge.

The controller 830 may output a control signal Sa to turn off the operation of the converter 810 when the abnormality is determined. Although not shown in the drawing, the controller 830 may further output a control signal for turning off the operation of the inverter 820 when the abnormality is determined. As described above, in the case where the capacitors are distributed at both ends of the capacitors C1 and C2 of several hundred volts (V), the presence or absence of abnormality can be easily determined, and various other circuit elements including the capacitors C1 and C2 may be used. You can protect it.

The controller 830 may further control the operation of the converter 810. This is the same as the description of FIG. 6.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical configuration of the present invention described above may be modified in other specific forms by those skilled in the art to which the present invention pertains without changing its technical spirit or essential features. It will be appreciated that it may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is represented by the claims to be described later rather than the detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

1 is a circuit diagram showing a conventional motor controller.

2 is a schematic diagram of an air conditioner according to the present invention.

3 is a circuit diagram illustrating a motor control apparatus according to an embodiment of the present invention.

4 is a circuit diagram illustrating a motor control apparatus according to an embodiment of the present invention.

5 is a simplified block diagram of the inside of the controller of FIG. 3.

6 is a simplified block diagram of the inside of the controller of FIG. 4.

7 is a circuit diagram illustrating a motor control apparatus according to an embodiment of the present invention.

8 is a circuit diagram illustrating a motor control apparatus according to an embodiment of the present invention.

<Explanation of symbols on main parts of the drawings>

305,405: Magnetic contactor 310,410,710,810: Converter

315,415,715,815: Voltage detector 320,420,720,820: Inverter

330,430,730,830: control unit 350,450,750,850: motor

A: input current detector C1, C2: capacitor

D: DC stage voltage detector E: Output current detector

La: reactor

Claims (16)

A converter for converting commercial AC power into DC power; An inverter having a plurality of switching elements, which receives the DC power and converts it into AC power having a predetermined frequency by a switching operation and supplies the same to a three-phase electric motor; A plurality of capacitors disposed between the converter and the inverter to smooth the DC power; A voltage sensing unit sensing a voltage applied to the capacitor; And And a controller which determines whether there is an abnormality of the sensed voltage and cuts off power when the abnormality is determined. The method of claim 1, The control unit, characterized in that for turning off the power of the inverter when the abnormality is determined. The method of claim 1, The control unit, characterized in that for cutting off the commercial AC power, characterized in that the electric motor control device. The method of claim 3, And a magnetic contactor connected between the commercial AC power source and the converter to transfer the commercial AC power source. And the control unit controls to turn off the magnetic contactor when the abnormality is determined. The method of claim 1, The control unit, And cut off the power when the sensed voltage is greater than or equal to a predetermined value. The method of claim 1, Some or all of the plurality of capacitors are connected in series with each other, And the sensing unit senses a voltage distributed between both ends of the capacitors connected in series with each other. The method of claim 1, The voltage detector, And a resistance element connected in parallel to the capacitor. The method of claim 1, The commercial AC power supply is a three-phase AC power supply. The method of claim 1, And a reactor arranged to be connected to the converter to remove harmonic currents. The method of claim 1, The control unit, An estimator for estimating a speed of the motor based on an output current detected from an output of the inverter; A current command generation unit that generates a d, q-axis current command value based on the estimated speed and speed command value; A voltage command generator for generating a d, q-axis voltage command value based on the current command value and the detected output current; And And a switching control signal output unit for outputting a switching control signal for driving the switching elements of the inverter. The method of claim 1, And an output current detector for detecting an output current which is the inverter output stage current. The method of claim 1, The converter includes a plurality of diode elements. The method of claim 1, And said converter comprises a plurality of switching elements and a plurality of diode elements. The method of claim 13, The control unit, characterized in that for turning off the power supply of the converter when the abnormality is determined. The method of claim 13, The control unit, A current command generation unit for generating a current command value based on a command value of a dc link stage voltage and a dc link stage voltage which are output terminals of the converter; A voltage command generator that generates a voltage command value based on the current command value and an input current from the commercial AC power supply; And And a switching control signal output unit configured to output a switching control signal for driving the switching elements of the converter. The method of claim 1, An input current detector for detecting an input current input from the commercial AC power supply; And And a dc stage voltage detector for detecting a dc stage current which is the converter output stage.

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