KR20130053248A - Apparatus and method for controlling inverter-motor - Google Patents

Abstract

PURPOSE: An inverter-motor control device and a method thereof are provided to improve reliability by preventing system instability. CONSTITUTION: An inverter part receives a DC(Direct Current) voltage and converts into an AC(Alternating Current) voltage. A sensor part detects a current flowing in a motor. A first comparator(140) outputs a first cut-off signal if an amplified voltage has a value bigger than a first voltage. A second comparator(150) outputs a second cut-off signal if the amplified voltage has a value smaller than a second voltage. A control part(160) receives the cut-off signals and interrupts the operation of the inverter part. [Reference numerals] (10) Indoor heat exchanger; (100) Inverter part; (110) Motor; (120) Sensor part; (130) Voltage amplifier part; (140) First comparator; (150) Second comparator; (160) Control part; (30) Compressor; (40) Expansion valve; (AA) Commercial power; (BB) Converter part; (CC,50) Blocking unit; (DD) Outdoor heat exchanger

Description

Inverter-motor control device and inverter-motor control method {APPARATUS AND METHOD FOR CONTROLLING INVERTER-MOTOR}

The present invention relates to an inverter-motor control device and an inverter-motor control method, and more particularly, to an inverter-motor control device and a control method for controlling an operation of an inverter by sensing a current flowing in a motor.

In general, the air conditioner exchanges heat in the required space to cool or heat the required space (ie, indoor). Heat exchange is performed by the refrigerant circulated along the refrigerant circulation loop. The refrigerant circulation loop causes the refrigerant to circulate in an evaporative compression manner. The amount of circulation of the refrigerant is regulated by an electric compressor installed on the refrigerant circulation loop.

A three-phase AC motor is mainly used as a motor for an electric compressor to adjust the amount of refrigerant to be circulated in the refrigerant circulation loop. In order to apply a voltage to a three-phase AC motor, a converter section for rectifying commercial AC power and an inverter section for generating a three-phase AC power by applying the rectified DC power to the motor are used.

If the AC power applied to the motor is lower than the negative voltage at which the motor can be normally driven, the motor may fail to start due to a pressure (load) inside the motor, or a fallout phenomenon may occur due to a low voltage. In addition, there is a problem that the system is in an unstable state because the desired rotation speed (RPM) is not obtained when a low voltage occurs during the operation of the motor. On the contrary, if the input power is higher than the positive voltage at which the motor can operate normally, the output current flowing into the motor increases, which may cause damage due to temperature rise or overcurrent of the component.

The present invention has been made to solve the above-described conventional problems, the inverter-motor control device to prevent the parts from being damaged or the system unstable when the input voltage is higher or lower than the reference voltage of the motor And an inverter motor control method.

Inverter-motor control apparatus according to an embodiment of the present invention receives a DC voltage, converts the inverter into an AC voltage, the motor is driven by applying an AC voltage, the current flowing through the motor by the AC voltage, the current A sensor unit for converting the voltage into a voltage, a first comparator for detecting the voltage converted by the sensor unit, and outputting a first cutoff signal when the voltage has a value equal to or greater than a preset first voltage, and And a second comparator for outputting a second cutoff signal and a controller for receiving the first cutoff signal or the second cutoff signal to stop the operation of the inverter unit when the voltage has a value of 2 voltage or less.

The inverter-motor control apparatus may further include a voltage amplifier configured to amplify the voltage converted by the sensor unit, and the first comparator and the second comparator may sense the voltage amplified by the voltage amplifier.

The first comparator may detect a duration of a voltage having a value greater than or equal to a predetermined first voltage and output a first blocking signal for the duration.

The second comparator may detect a duration of a voltage having a value less than or equal to a predetermined second voltage and output a second blocking signal for the duration.

In the inverter-motor control method according to an embodiment of the present invention, the AC voltage is applied from the inverter unit to drive the motor, by detecting the current flowing in the motor by the AC voltage applied to the motor, and converts the current to a voltage Performing a first voltage determination step of determining whether the converted voltage value has a value greater than or equal to a first predetermined voltage; and stopping the operation of the inverter unit when the converted voltage value has a value greater than or equal to the first voltage. A second voltage determination step of determining whether the converted voltage value has a value less than or equal to a preset second voltage and a second inverter stopping step of stopping operation of the inverter unit when the converted voltage value has a value less than or equal to the second voltage; It includes.

Inverter-motor control device according to the present invention, even when a power supply higher or lower than the reference voltage of the motor is applied to the motor, it is possible to secure the reliability of the control device by preventing the burnout of component elements of the motor or system instability There is.

1 is an exemplary view of an air conditioner in which an inverter-motor control apparatus according to an embodiment of the present invention may be mounted.
2 is a block diagram of an air conditioner in which an inverter-motor control apparatus according to an embodiment of the present invention may be mounted.
3 is an exemplary view illustrating a first blocking signal and a second blocking signal of an inverter-motor control apparatus according to an exemplary embodiment of the present invention.
4 is a flowchart illustrating an inverter-motor control method according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. In the following description, the same constituent elements are given the same names and the same symbols for convenience of explanation.

The terminology used in the present invention was selected as a general term that is widely used at present, but in some cases, the term is arbitrarily selected by the applicant, and in this case, the meaning of the term is described in detail in the description of the present invention. The present invention should be understood as meanings other than terms.

1 is an exemplary view of an air conditioner in which an inverter-motor control apparatus according to an embodiment of the present invention may be mounted. As shown, the air conditioner includes an indoor heat exchanger 10 for air conditioning the room, and an outdoor heat exchanger 20 connected to the indoor heat exchanger 10 by a refrigerant pipe. An air conditioner is to be understood as a device that air conditioners indoors in a broad sense, and includes a concept that includes all processes of cooling or heating the room, humidifying or dehumidifying the room air, or purifying the room air. do.

2 is a block diagram of an air conditioner in which an inverter-motor control device 60 according to an embodiment of the present invention may be mounted. As shown, the air conditioner includes a compressor 30 and an expansion valve 40 (electric expansion valve), together with an outdoor heat exchanger 20 and an indoor heat exchanger 10, for circulation of the refrigerant, A converter unit 20 and an inverter-motor control device 60 for powering the compressor 30 are included.

When the air conditioner performs a cooling operation, the discharge refrigerant from the compressor 30 is expanded under reduced pressure in the expansion valve 40 through the outdoor heat exchanger 20, and passes through the indoor heat exchanger 10 to the electric compressor ( Return to 30). In this case, the outdoor heat exchanger 20 functions as a condenser and the indoor heat exchanger 10 functions as an evaporator. As a result, the refrigerant circulation loop causes the air in the required space in which the indoor heat exchanger 10 is installed to cool.

On the other hand, when the air conditioner performs the heating operation, the discharged refrigerant from the compressor 30 passes through the indoor heat exchanger 10, and then expands under reduced pressure in the expansion valve 40, and the outdoor heat exchanger 20. Return to the compressor (30). In this case, the indoor heat exchanger 10 functions as a condenser and the outdoor heat exchanger 20 functions as an evaporator. The refrigerant circulating in the refrigerant circulation loop thus heats the air in the required space (ie, indoor) where the indoor heat exchanger 10 is located.

In addition, the indoor heat exchanger 10 and the outdoor heat exchanger 20 are provided with a blowing fan so that the indoor air and the outdoor air is blown during the process of heat exchange with each heat exchanger. Therefore, the air blown to the indoor heat exchanger 10 during the process of evaporating or condensing the refrigerant in the indoor heat exchanger 10 is heat exchanged with the indoor heat exchanger 10 to cool or heat the air. To cool or heat the room.

The compressor 30 sucks low-temperature, low-pressure gas refrigerant evaporated from the indoor heat exchanger 10 and increases the pressure and temperature to a saturation pressure corresponding to the condensation temperature so as to easily condensate the liquid in the outdoor heat exchanger 20. The compressor 30 may include the motor 110 or may be configured separately.

In order to drive the motor 110, the converter unit 20 may include a diode element, and receives a single-phase AC voltage from the commercial power supply 70 to rectify the DC voltage. In addition, the converter unit 20 may further include a DC link capacitor that generates a DC link voltage by smoothing the rectified DC voltage of the converter unit 20. Thereafter, the converter unit 20 outputs a DC voltage to the inverter unit 100.

The inverter-motor controller 60 includes an inverter unit 100, a motor 110, a sensor unit 120, a voltage amplifier 130, a first comparator 140, a second comparator 150, and a controller 160. ) May be included.

First, the inverter unit 100 converts the smoothed DC voltage into a three-phase AC voltage of a predetermined frequency and supplies the three-phase AC voltage to the motor 110.

The motor 110 includes a stator and a rotor, and an alternating current power of a predetermined frequency is applied to a coil of each stator so that the rotor rotates. The type of the motor 110 may be various forms such as a BLDC motor, a synRM motor, an induction motor.

Therefore, the motor 110 is driven by receiving a three-phase AC voltage from the inverter, thereby generating an alternating current.

The sensor unit 120 detects an output current flowing in the motor 110. The sensor unit 120 may detect the output current of each phase, or may detect the output current of one or two phases using three-phase balance.

The sensor unit 120 converts the sensed output current into a voltage. The sensed output current is a pulsed signal, and the converted voltage may also be a pulsed signal. The waveform of the voltage converted from the sensor unit 120 will be described later with reference to FIG. 3.

The voltage amplification unit 130 includes an operational amplifier (op-amp) and amplifies the voltage output from the sensor unit 120 to facilitate the voltage sensing and blocking signal output in the comparator which will be described later. When the voltage value output from the sensor unit 120 is small, the voltage amplifying unit 130 amplifies it to make a voltage having a large amplitude, and the comparator makes it easy to compare the amplified voltage with a preset cutoff voltage value. Can be.

The first comparator 140 receives the amplified voltage and outputs a first fault out signal when the voltage has a value greater than or equal to a preset first voltage. The reason for setting the first voltage value and comparing it with the voltage converted from the detected current is to protect the inverter, the motor 110 and the circuit including the same. That is, since the circuit is damaged when the voltage exceeds the first voltage value, the first comparator 140 outputs the first blocking signal to the controller 160.

The second comparator 150 receives the amplified voltage and outputs a second fault out signal when the voltage has a value less than or equal to the preset second voltage. If the voltage is lower than the second voltage value, the circuit is damaged, so that the second comparator 150 outputs the second blocking signal to the controller 160.

The controller 160 may output a pulse amplitude modulation (PAM) control signal or a pulse width modulation (PWM) control signal to the inverter in order to control the inverter unit 100. In addition, when the first blocking signal or the second blocking signal is input from the first comparator 140 or the second comparator 150, the controller 160 immediately stops driving the motor 110. That is, when receiving the blocking signal, the controller 160 may output a signal for controlling the inverter unit 100 to stop driving of the motor 110.

In addition, the controller 160 may control the blocking unit 50 to stop supply of the commercial AC power or to block the DC voltage rectified by the converter 20. Therefore, when the first comparator 140 or the second comparator 150 outputs the cutoff signal, the controller 160 may control the inverter or the cutoff unit 50, so that the inverter-motor control device 60 is a circuit component. It has the effect of preventing breakage and stabilizing the system.

3 is an exemplary view illustrating a first blocking signal and a second blocking signal of the inverter-motor control apparatus 60 according to an exemplary embodiment of the present invention. As shown, the voltage amplified by the voltage amplifier 130 by converting the current sensed by the sensor unit 120 into a voltage appears in the form of a pulse. In this case, the first comparator 140 outputs a cutoff signal when the amplified voltage has a value greater than or equal to the first cutoff voltage value, and the second comparator 150 has a value less than or equal to the second cutoff voltage value. In case of outputting cutoff signal.

When the voltage is greater than or equal to the first blocking voltage, the first comparator 140 continuously outputs the blocking signal, and stops outputting the blocking signal as soon as the voltage is lowered below the first blocking voltage. In addition, the second comparator may continuously output the blocking signal when the voltage is less than or equal to the second blocking voltage, and stop the output of the blocking signal as soon as the voltage becomes higher than the second blocking voltage. That is, while the voltage exceeds or falls below the first blocking voltage and the second blocking voltage, the comparator may continuously output the blocking signal.

The various embodiments described herein may be embodied in a recording medium readable by a computer or similar device using, for example, software, hardware, or a combination thereof.

According to a hardware implementation, the embodiments described herein include application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), and the like. It may be implemented using at least one of processors, controllers, micro-controllers, microprocessors, and electrical units for performing other functions. These may be implemented by the controller 160.

According to a software implementation, embodiments such as procedures or functions may be implemented with separate software modules that perform at least one function or operation. The software code may be implemented by a software application written in a suitable programming language. Hereinafter, an inverter-motor control method according to an exemplary embodiment of the present invention will be described with reference to FIG. 4.

4 is a flowchart illustrating an inverter-motor control method according to an exemplary embodiment of the present invention. As shown, the sensor unit 120 detects the motor current (S10). The motor 110 is driven by an alternating voltage, and at this time, the sensor unit 120 senses a current flowing in the motor 110 and converts it into a voltage (S20).

Next, the voltage amplifier 130 amplifies the converted voltage (S30). This is to amplify the voltage converted by the sensor unit 120 to perform a precise comparison using the voltage amplified by the first comparator 140 and the second comparator 150. For example, when comparing voltages without amplification, since the amplitude of the voltages is not large, the comparator has difficulty in comparing the converted voltage and the cutoff voltage value. However, since the amplified voltage is large in amplitude, the comparator can easily compare the amplified voltage with the blocking voltage.

Thereafter, the first comparator 140 and the second comparator 150 sense the amplified voltage (S40), and the first comparator 140 compares the voltage with the first blocking voltage to determine whether the voltage is higher than the first blocking voltage. The determination is made (S50). When the voltage is higher than the first blocking voltage, the first blocking signal is output. If the voltage is lower than the first blocking voltage, the second comparator 150 determines whether the voltage is lower than the second blocking voltage in step S60. The second comparator 150 outputs the second blocking signal when the voltage is lower than the second blocking voltage, and measures the voltage again when the voltage is higher than the second blocking voltage.

The controller 160 controls the inverter unit 100 when receiving the first blocking signal and the second blocking signal from the first comparator 140 and the second comparator 150, respectively (S70). That is, the controller 160 outputs a signal to stop the operation of the inverter unit 100 to the inverter unit 100, or operates the cut-off unit 50 so that no current flows through the inverter unit 100 to damage the circuit. It can prevent.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

Claims (8)

An inverter unit for receiving a DC voltage and converting the same into an AC voltage;
A motor driven by being applied with the AC voltage;
A sensor unit which senses a current flowing in the motor by the AC voltage and converts the current into a voltage;
A first comparator that senses the voltage converted by the sensor unit and outputs a first cutoff signal when the voltage has a value equal to or greater than a predetermined first voltage;
A second comparator that senses the voltage and outputs a second blocking signal when the voltage has a value less than or equal to a preset second voltage; And
A control unit configured to stop the operation of the inverter unit by receiving the first blocking signal or the second blocking signal;
Inverter-motor control device comprising a. The method according to claim 1,
Further comprising a voltage amplifier for amplifying the voltage converted by the sensor unit,
And the first comparator and the second comparator sense a voltage amplified by the voltage amplifier. The method according to claim 1,
Wherein the first comparator comprises:
Inverter-motor control device for detecting the duration of the voltage having a value of more than the first predetermined voltage, and outputs the first cut-off signal during the duration. The method according to claim 1,
Wherein the second comparator comprises:
Inverter-motor control device for detecting the duration of the voltage having a value less than the second predetermined voltage, and outputs the second blocking signal during the duration. Applying an AC voltage from the inverter unit to drive the motor;
Detecting a current flowing in the motor by the AC voltage applied to the motor and converting the current;
A first voltage determination step of determining whether the converted voltage value has a value equal to or greater than a first predetermined voltage;
A first inverter stopping step of stopping the operation of the inverter unit when the converted voltage value has a value equal to or greater than the first voltage;
A second voltage determination step of determining whether the converted voltage value has a value less than or equal to a preset second voltage; and
A second inverter stopping step of stopping the operation of the inverter unit when the converted voltage value has a value less than or equal to the second voltage;
Inverter-motor control method comprising a. 6. The method of claim 5,
Amplifying the converted voltage;
Further comprising:
The first voltage determination step,
Sensing the amplified voltage and determining whether the amplified voltage has a value equal to or greater than the first voltage,
The second voltage determination step,
Sensing the amplified voltage and determining whether the amplified voltage has a value less than or equal to the second voltage. 6. The method of claim 5,
The first inverter stop step,
Detecting a duration of the voltage having a value equal to or greater than a first predetermined voltage, and stopping the operation of the inverter unit during the duration. 6. The method of claim 5,
The second inverter stop step,
Detecting a duration of the voltage having a value less than or equal to a second predetermined voltage, and stopping the operation of the inverter unit for the duration.

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