KR20100036780A - Motor controller - Google Patents

Abstract

PURPOSE: A motor controller is provided to efficiency protect a protection device by stopping an inverter when at least detected offsets are out of a preset range. CONSTITUTION: An inverter(220) changes inputted DC power to AC power by a switching operation and includes a plurality of switching elements and shunt resistors. The shunt resistor is connected to each switching element. A current detector(240) detects the three phase current which flows in the inverter and detects the offset based on the detected current. If at least two detected offsets are out of a preset range, a controller(230) stops the operation of the inverter.

Description

Motor controller

The present invention relates to an electric motor control device, and more particularly, to an electric motor control device capable of efficiently protecting circuit elements.

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.

Air conditioners are generally divided into one-piece and separate types. The integrated type and the separate type are functionally the same, but the integrated type integrates the functions of cooling and heat dissipation to install a hole in the wall of the house or hang the device on the window, and the separate type installs an indoor unit that performs cooling / heating on the indoor side and outdoor. On the side, an outdoor unit that performs heat dissipation and compression functions was installed, and two separate devices were connected by refrigerant pipes.

In the air conditioner, an electric motor is used for a compressor, a fan, and the like, and an electric motor control device for driving the air conditioner is used. The motor control apparatus receives a commercial AC power and converts it into a DC voltage, converts the DC voltage into a commercial AC power having a predetermined frequency, and supplies the same to the motor, thereby controlling the motor to drive a motor such as a compressor or a fan.

On the other hand, the motor controller uses a high voltage and a high current to drive the motor, thereby increasing the possibility of damage to most circuit elements in the motor controller, various measures have been proposed to protect this.

It is an object of the present invention to provide an electric motor control device capable of efficiently securing the safety of circuit elements in the control device.

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 plurality of switching elements, and converts the input DC power to AC power by switching operation to drive a three-phase motor The inverter detects the three-phase current flowing through the inverter, respectively, and detects an offset based on the detected current, and if at least two of the detected offsets are out of a predetermined range, it is determined that the inverter is abnormal. And a control unit for controlling to stop the operation.

As described above, the motor control apparatus according to the embodiment of the present invention controls to stop the operation of the inverter by determining that it is abnormal operation when at least two of the detected offsets out of the detected offsets are out of a predetermined range. It is possible to ensure the stability of the elements in the arc in the device. Furthermore, when any one of the detected offsets is out of a predetermined range, it is determined that the operation is normal, thereby preventing the occurrence of an error due to a current detection error or an offset detection error, thereby improving the safety of the entire circuit elements in the control device. It can be secured efficiently.

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

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

Referring to the drawings, the air conditioner 40 is largely divided into an indoor unit (I) and an outdoor unit (O).

The outdoor unit O includes a compressor 2 serving to compress the refrigerant, a compressor electric motor 2b for driving the compressor, an outdoor side heat exchanger 4 serving to radiate the compressed refrigerant, and an outdoor unit. An outdoor blower 4 disposed on one side of the heat exchanger 4 and including an outdoor fan 4a for promoting heat dissipation of the refrigerant and an electric motor 4b for rotating the outdoor fan 4a, and an expansion for expanding the condensed refrigerant; A mechanism (4), a cooling / heating switching valve (10) for changing the flow path of the compressed refrigerant, and an accumulator (4) for temporarily storing gasified refrigerant to remove moisture and foreign matter and then supplying a refrigerant of a constant pressure to the compressor. And the like.

The indoor unit (I) is disposed in the room to perform the cooling / heating function of the indoor side heat exchanger (5), and the indoor fan (9a) and the room arranged on one side of the indoor side heat exchanger (5) to promote heat dissipation of the refrigerant. And an indoor blower 9 made of an electric motor 9b for rotating the fan 9a.

At least one indoor side heat exchanger (5) may be installed. The compressor 2 may be at least one of an inverter compressor and a constant speed compressor.

In addition, the air conditioner 40 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 electric motor in the motor control apparatus according to an embodiment of the present invention may be each electric motor (2b, 5b, 9b) for operating the outdoor fan, compressor or indoor fan of the air conditioner, shown in the figure.

Figure 2 is a circuit diagram showing a motor control apparatus according to an embodiment of the present invention,

3 is a block diagram schematically illustrating a current detector, and FIG. 4 is a diagram referred to describe offset detection in the current detector of FIG. 3.

2 to 4, the motor control apparatus 200 of FIG. 2 according to an exemplary embodiment of the present invention may include a converter 210, an inverter 220, a controller 230, and a current detector 240. Include. In addition, the motor control apparatus 200 of FIG. 2 may further include a reactor L, a smoothing capacitor C, and the like.

The reactor L is disposed between the commercial AC power supply 205 and the converter 210 to perform power factor correction or step-up operation. In addition, the reactor L may perform a function of limiting harmonic currents due to the fast switching of the converter 210.

The converter 210 converts the commercial AC power source 205 passed through the reactor L into a DC power source and outputs the DC power source. Although the commercial AC power supply 205 is shown as a single phase AC power supply in the figure, it may be a three phase AC power supply. The internal structure of the converter 210 also varies according to the type of the commercial AC power source 205. For example, in the case of a single phase AC power supply, a half bridge type converter in which two switching elements and four diodes are connected may be used, and in the case of a three phase AC power supply, six switching elements and six diodes may be used.

The converter 210 includes a plurality of switching elements and performs a boosting operation, power factor improvement, and DC power conversion by a switching operation. On the other hand, the converter 210 may be made of a diode or the like to perform rectification without a separate switching operation.

The smoothing capacitor C is connected to the output terminal of the converter 210. The converted DC power output from the converter 210 is smoothed. Hereinafter, the output terminal of the converter 210 is referred to as a dc terminal or a dc link terminal. The DC voltage smoothed at the dc stage is applied to the inverter 220.

The inverter 220 includes a plurality of inverter switching elements, converts a smoothed DC power source into a three-phase AC power source having a predetermined frequency by on / off operation of the switching element, and outputs the same to the three-phase electric motor 250.

Inverter 220 is a pair of upper arm switching elements (Sa, Sb, Sc) and lower arm switching elements (S'a, S'b, S'c) connected in series with each other, a total of three pairs of upper and lower arms The switching elements are connected in parallel with each other (Sa & S'a, Sb & S'b, Sc & S'c). Diodes are connected in anti-parallel to each of the switching elements Sa, S'a, Sb, S'b, Sc, and S'c.

The switching elements in the inverter 220 perform on / off operations of the respective switching elements based on the inverter switching control signal Sic from the controller 230. As a result, the three-phase AC power supply having the predetermined frequency is output to the three-phase electric motor 250.

In addition, the inverter 220 further includes shunt resistors Ra, Rb, and Rc connected to the respective lower arm switching elements S'a, S'b, and S'c. The shunt resistors Ra, Rb, and Rc are used to detect three-phase currents ia, ib and ic flowing in the inverter 220.

The current detector 240 detects a current value of the three-phase currents (ia, ib, ic) flowing through the inverter 220, and detects an offset based on the detected current value. To this end, the current detector 240 includes an A / D converter 310 and an offset detector 320.

The A / D converter 310 converts the three-phase current value (ia, ib, ic) in the analog form shown in FIG. 4 into discrete digital values A / D converted. The value of the A / D converted detection current may be smaller than the value of the detection current before A / D conversion. Meanwhile, the A / D converter 310 may convert the input three-phase current values ia, ib and ic into a predetermined digital voltage value A / D converted.

The offset detector 320 detects an offset based on the value of the A / D converted detection current output from the A / D converter 310. This offset may be an average value (oa, ob, oc) of the three-phase current value (ia, ib, ic) in the analog form, as shown in FIG. The offset value detected here may be a current value, but is not limited thereto and may be detected in the form of a voltage value. Meanwhile, the offset detector 320 may be implemented in the form of an op amp to detect the offset of the three-phase current through comparison with a predetermined value.

The offset value detected by the offset detector 320 is input to the controller 230.

The controller 230 determines that the operation is abnormal when at least two offsets of the detected offsets are out of a predetermined range. For example, when two offsets (oa, ob) of the three offset values (oa, ob, oc) are in an abnormal range, the operation of the inverter 220 is stopped by determining that the motor control apparatus 200 is abnormal. Let's do it. That is, all the switching elements in the inverter 220 are turned off. As a result, it is possible to prevent the burnout of the circuit elements in the motor control device due to the abnormal operation.

On the other hand, the controller 230 determines that the operation is normal when at least two of the detected offsets are within a predetermined range. For example, when it is determined that two offsets (oa, ob) of the three offset values (oa, ob, oc) are within a normal range and one offset (oc) is an abnormal range, this is determined as normal operation. do. The wiring structure of the motor 250 is a Y connection. Since the sum of the values of the three-phase currents (ia, ib, ic) in the analog form is 0, two offsets (oa, ob, oc) of the three offset values (oa, ob, oc) are obtained. As long as ob) is within the normal range, it is determined that one offset oc is in the abnormal range due to a detection error or the like. Accordingly, due to the detection error, it is possible to prevent the operation of the inverter is stopped in a consumable manner, and it is possible to efficiently protect the circuit elements in the motor control apparatus 200.

On the other hand, the controller 230 compares the detected three offset values (oa, ob, oc) with a predetermined offset reference value, and determines whether the detected offset is within a predetermined range. The offset reference value may be the same value for all three offset values (oa, ob, oc).

In addition, the controller 230 controls the switching operation of the inverter 220. To this end, the controller 230 may further receive a detection current value in addition to the offset values (oa, ob, oc) from the current detector 240.

The controller 230 outputs an inverter switching control signal Sic to the inverter 220 in order to control the switching operation of the inverter 220. The inverter switching control signal Sic is a PWM switching control signal, which is generated and output based on the detected current values ia, ib and ic from the current detector 240. Detailed operation of the output of the inverter switching control signal (Sic) in the control unit 230 will be described later with reference to FIG.

Three-phase electric motor 250 is provided with a stator and a rotor, each phase AC power of a predetermined frequency is applied to the coil of each stator, the rotor is rotated. The type of the motor 250 may be various forms such as a BLDC motor, synRM motor.

The three-phase electric motor 250 may be used as a fan motor or a compressor motor in an outdoor unit of an air conditioner, and may also be used as a fan motor in an indoor unit of an air conditioner.

Meanwhile, when the converter 210 includes a switching element to perform a switching operation, the controller 230 may control the converter. For this purpose, the control unit 230 may further include an input current detecting unit and a dc terminal voltage detecting unit. .

5 is an internal block diagram of the controller of FIG. 2.

Referring to the drawings, the controller 230 may include an estimator 305, a current command generator 310, a voltage command generator 320, and a switching control to output an inverter switching control signal Sic. It may include a signal output unit 330.

The estimator 305 estimates the position and speed v of the rotor of the electric motor based on the output current i _o detected by the current detector 240. Meanwhile, the detected output current i _o may be the three-phase current values ia, ib, and ic described above.

The current command generator 310 generates a d, q-axis current command value i ^* _d , i ^* _q through a PI controller or the like based on the estimated speed v and the speed command value v ^* .

The voltage command generation unit 320 generates a d, q-axis voltage command value (v ^* _d) through a PI controller or the like based on the d, q-axis current command value (i ^* _d , i ^* _q ) and the detected output current (i _o ). , v ^* _q )

The switching control signal output unit 330 transmits the inverter switching control signal Sic to the controller 230 to drive the switching element in the inverter 220 based on the d, q-axis voltage command values v ^* _d and v ^* _q . Output

6 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 600 of FIG. 6 includes a converter 610, an inverter 620, a controller 630, and a current detector 640. In addition, the motor control apparatus 600 of FIG. 6 may further include a reactor 605, a smoothing capacitor C, an input current detecting means (not shown), and a dc terminal voltage detecting means (not shown).

The motor controller 600 of FIG. 6 is almost similar to the motor controller 200 of FIG. That is, the operations of the converter 610, the inverter 620, and the current detector 640 are the same as the operations of the converter 210, the inverter 220, and the current detector 240 of FIG. 2. However, there is a difference in that the controller 600 of FIG. 6 controls the converter 610 and the inverter 620 together. Hereinafter, only the difference will be described.

If at least two of the detected offsets are out of a predetermined range, the controller 630 determines that the operation is abnormal and stops the operations of the converter 610 and the inverter 620 together. For example, when two offsets (oa, ob) of the three offset values (oa, ob, oc) are in an abnormal range, the converter 610 and the inverter 620 are determined to be abnormal operation of the motor controller 600. ) Is stopped. That is, all the switching elements in the converter 610 and the inverter 620 are turned off. Accordingly, it is possible to prevent the burnout of the circuit elements in the motor control apparatus 600 due to the abnormal operation.

On the other hand, the controller 630 determines that the operation is normal when at least two offsets of the detected offsets are within a predetermined range. Accordingly, the controller 630 controls the converter 610 and the inverter 620 to operate normally.

On the other hand, the controller 630, in order to control the switching operation of the converter 610 and the inverter 620, the converter switching control signal (Scc) and the inverter switching control signal (Sic), respectively, the converter 610 and the inverter (620) ) A detailed operation of the output of the inverter switching control signal Sic is omitted with reference to FIG. 5, and a detailed operation of the output of the converter switching control signal Scc will be described later with reference to FIG. 7.

On the other hand, the input current detecting means (not shown) detects the input current i _i input from the commercial AC power supply 205. To this end, a current sensor, a CT (current trnasformer), a shunt resistor, or the like may be used as the input current detecting means (not shown). The detected input current i _i is input to the controller 630 to generate the converter switching control signal Scc.

On the other hand, the dc terminal voltage detection means (not shown) detects the dc terminal voltage (Vdc) that is both ends of the smoothing capacitor (C). To this end, the dc end voltage detection means (not shown) includes a resistor or the like. The detected dc terminal voltage Vdc is input to the controller 630 to generate the converter switching control signal Scc.

FIG. 7 is an internal block diagram of the controller of FIG. 6.

Referring to the drawings, the controller 630 includes a current command generator 710, a voltage command generator 720, and a switching control signal output unit 730.

The current command generation unit 710 generates a d, q-axis current command value (i ^* _d , i ^* _q ) through a PI controller or the like based on the detected dc end voltage (Vdc) and the dc end voltage command value (V ^* dc). Create

The voltage command generation unit 720 performs a d, q-axis voltage command value (v ^* _d) through a PI controller or the like based on the d, q-axis current command value (i ^* _d , i ^* _q ) and the detected input current (i _i ). , v ^* _q )

The switching control signal output unit 730 transmits the converter switching control signal Scc to the controller 630 to drive the switching element in the converter 610 based on the d, q-axis voltage command value v ^* _d , v ^* _q . Output

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention 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 shown by the claims below, rather than the above 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 schematic diagram of an air conditioner according to the present invention.

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

3 is a block diagram schematically illustrating a current detector.

4 is a diagram referred to describe offset detection in the current detector of FIG. 3.

5 is an internal block diagram of the controller of FIG. 2.

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

FIG. 7 is an internal block diagram of the controller of FIG. 6.

<Explanation of symbols on main parts of the drawings>

210,610: Converter 220,620: Inverter

230,630: controller 240,640: current detector

Claims (9)

An inverter having a plurality of switching elements and converting an input DC power source into an AC power source by a switching operation to drive a three-phase electric motor; A current detector which detects three-phase currents flowing through the inverter, and respectively detects offsets based on the detected currents; And And a controller configured to control to stop the operation of the inverter when it is determined that the at least two offsets of the detected offset are out of a predetermined range. The method of claim 1, The control unit, And at least two of the detected offsets are within the predetermined range, determining that the operation is normal, and controlling the operation of the inverter. The method of claim 1, The control unit, And comparing the detected offset with a predetermined offset reference value to determine whether it is within the predetermined range of the detected offset. The method of claim 1, The inverter, Three pairs of upper and lower arm switching elements connected in parallel with each other by using a pair of upper arm switching elements and a lower phase switching element connected in series with each other; And And a shunt resistor connected to each of the lower arm switching elements. The method of claim 4, wherein The current detector, An A / D converter configured to A / D convert current flowing through each of the shunt resistors; And And an offset detector for detecting an offset from the A / D converted detection current. The method of claim 1, And a converter for converting commercial AC power into the DC power. The method of claim 6, The control unit, And at least two offsets of the detected offsets are out of a predetermined range, determining that the operation is abnormal and stopping the operation of the inverter and the converter. The method of claim 1, The control unit, An estimator for estimating a speed based on the detected current value; A current command generation unit that generates a current command value based on the estimated speed and the speed command value; A voltage command generator for generating a voltage command value based on the current command value and the output current; And And a switching control signal output unit configured to generate and output an inverter switching control signal based on the voltage command value. The method of claim 6, The control unit, A current command generator for generating a current command value based on the detected dc terminal voltage which is an output terminal voltage of the converter; A voltage command generation unit 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 generate and output a converter switching control signal based on the voltage command value.

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