KR20190089659A - Apparatus and method for driving inverter - Google Patents

Abstract

The present invention relates to a device for driving an inverter and a method thereof and, more specifically, to a device for driving an inverter capable of continuous driving of an inverter by limiting driving of the inverter in accordance with a junction temperature, and a method thereof. According to an embodiment of the present invention, the device for driving an inverter comprises: an information collection unit collecting operation information of an inverter driving a motor; a loss calculation unit calculating a power loss of a power module forming the inverter based on the collected operation information; a junction temperature calculation unit calculating a junction temperature of the power module based on the calculated power loss and a thermal coefficient of resistivity of the power module; and an inverter control unit limiting driving of the inverter when the calculated junction temperature is equal to or greater than a protection temperature, and less than a limitation temperature.

Description

[0001] APPARATUS AND METHOD FOR DRIVING INVERTER [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter driving apparatus and method, and more particularly, to an inverter driving apparatus and method that enable continuous driving of an inverter by restricting drive of the inverter according to a junction temperature.

The air conditioner is a device for adjusting indoor temperature or purifying indoor air by discharging cold air to create a pleasant indoor environment. Generally, the air conditioner is composed of an indoor unit installed in a room and an outdoor unit supplying refrigerant to the indoor unit.

The outdoor unit is provided with a motor for driving the compressor and an inverter for driving the motor by outputting three-phase alternating current to the motor.

The inverter includes a plurality of power switching elements. The plurality of power switching elements performs a turn-on and a turn-off operation (switching operation) to convert the DC voltage into a three-phase alternating current, Output.

As the power switching device repeats the switching operation, a power loss due to the power conversion occurs in the power switching device, and such power loss is released as heat, and the junction temperature of the power switching device increases.

Since the power switching device operates normally within a certain temperature range, if the junction temperature exceeds the driving limit temperature, malfunction of the power switching device may occur.

Accordingly, prediction of the junction temperature is an important issue in driving the inverter, and various methods for predicting the junction temperature have been proposed. For example, Korean Patent No. 10-1567256 discloses a method of predicting the junction temperature of an inverter.

When the junction temperature continuously rises due to continuous driving of the air conditioner, the conventional inverter driving method according to the junction temperature only determines whether or not the junction temperature exceeds the drive limit temperature, and determines whether to drive or stop the drive.

Accordingly, according to the conventional inverter driving method, since the junction temperature can not be lowered unless the user restricts the driving of the air conditioner, there is a problem that the inverter can not be continuously driven.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inverter driving apparatus and method for limiting the drive of an inverter according to a junction temperature.

It is another object of the present invention to provide an inverter driving apparatus and method for restricting drive of an inverter in other ways according to the speed of a motor.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description and more clearly understood by the embodiments of the present invention. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

The present invention can determine the operation mode of the inverter by calculating the junction temperature, comparing the calculated junction temperature with the protection temperature and the limit temperature, and driving the inverter according to the operation mode to limit the drive of the inverter according to the junction temperature have.

In addition, the present invention uses a discontinuous pulse width modulation (DPWM) method when the speed of the motor is higher than the reference speed in limiting the drive of the inverter, and when the speed of the motor is lower than the reference speed, The drive of the inverter can be limited in other ways depending on the speed of the motor.

According to the present invention, by limiting the drive of the inverter according to the junction temperature, the junction temperature can be lowered and the inverter can be continuously driven.

Further, the present invention has an effect of efficiently driving the inverter while lowering the junction temperature by restricting the drive of the inverter in other ways according to the speed of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a state in which an inverter driving apparatus of the present invention drives an inverter; Fig.
Fig. 2 is a diagram showing a detailed configuration and a control flow of the inverter driving apparatus shown in Fig. 1; Fig.
3 shows a detailed configuration of the power module shown in Fig. 1; Fig.
4 is a view showing a state in which a junction temperature of an IGBT is actually measured using a thermocouple.
5 is a graph showing an operation mode of the inverter determined according to the calculated junction temperature.
6 is a flowchart showing an inverter driving method according to an embodiment of the present invention;
7 is a flowchart showing a method of determining an operation mode according to a junction temperature and driving an inverter according to an operation mode;

The above and other objects, features, and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, which are not intended to limit the scope of the present invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to denote the same or similar elements.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter driving apparatus and method, and more particularly, to an inverter driving apparatus and method that enable continuous driving of an inverter by limiting drive of the inverter according to junction temperature.

Hereinafter, an inverter driving apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5. FIG.

FIG. 1 is a view showing a driving apparatus of an inverter according to the present invention driving an inverter, and FIG. 2 is a diagram showing a detailed configuration and a control flow of the inverter driving apparatus shown in FIG.

FIG. 3 is a view showing a detailed configuration of the power module shown in FIG. 1, and FIG. 4 is a view showing a measurement of the junction temperature of the IGBT using a thermocouple.

5 is a graph showing an operation mode of the inverter determined according to the calculated junction temperature.

1, the inverter 10 includes a DC link capacitor that stores the direct-current voltage of a predetermined size (C _DC) driven by the inverter driving unit 100 and, the DC link voltage stored in the DC link capacitor (C _DC) (V _DC ) to a three-phase alternating current.

The DC link capacitor C _DC may receive power from an arbitrary voltage source (Source) 20 and store the DC link voltage V _DC . Here, the voltage source 20 may be a three-phase grid for supplying three-phase AC power, or may be a DC voltage source for supplying a constant DC voltage.

When the voltage source 20 is a three-phase AC power source, an AC-DC converter (not shown) may be further provided between the DC link capacitor C _DC and the voltage source 20 to convert the AC power to DC power. Meanwhile, a DC-DC converter (not shown) may be further provided between the DC link capacitor C _DC and the voltage source 20 to increase or decrease the DC voltage when the voltage source 20 is a DC voltage.

The power module 11 may include a plurality of power switching elements, and the plurality of power switching elements perform turn-on and turn-off operations (switching operations) by the inverter driving apparatus 100 to generate DC link capacitors C _DC Phase AC current stored in the DC link voltage (V _DC ).

The power switching device may be a bipolar junction transistor (BJT), a metal oxide semiconductor field effect transistor (MOSFET), or an insulated gate bipolar mode transistor (IGBT). However, in the present invention, it is assumed that the switching device included in the inverter 10 is an IGBT, and the specific configuration of the power module 11 will be described later.

The three-phase alternating current converted by the power module 11 is outputted to the motor 30, and the motor 30 can be driven by using the three-phase alternating current as a power source. Here, the motor 30 may be a motor for driving a compressor in an air conditioner.

In other words, the inverter 10 can output the three-phase alternating current to drive the motor 30, and the motor 30 can drive the compressor in the air conditioner through the rotary motion.

The compressor in the air conditioner receives and compresses the refrigerant, and the heat exchanger in the air conditioner can heat-exchange the compressed refrigerant and the outdoor air, and the general operation of such an air conditioner is well known in the art Because it is widely known, a detailed explanation is omitted here.

2, an inverter driving apparatus 100 according to an embodiment of the present invention includes an information collecting unit 110, a loss calculating unit 120, a junction temperature calculating unit 130, an inverter controlling unit 140, (150). The inverter driving apparatus 100 shown in Fig. 2 is according to one embodiment, and the constituent elements thereof are not limited to the embodiment shown in Fig. 2, and some elements may be added, changed or deleted have.

The information collecting unit 110, the loss calculating unit 120, the junction temperature calculating unit 130, and the inverter controlling unit 140 may each include a processor for performing each of the functions described below. Alternatively, each function of the information collecting unit 110, the loss calculating unit 120, the junction temperature calculating unit 130, and the inverter controlling unit 140 may be performed by a single processor.

Such a processor can perform each function with reference to the memory 150. To this end, the memory 150 stores device information of each element constituting the inverter 10, for example, the turn-on loss (E etc. emitter saturation resistance (R _CE) - _ON) and turn-off loss (E _oFF), the gate resistance (R _G), a collector-emitter saturation (collector-emitter saturation) voltage (V _CE (sat)), the collector A look-up table (LUT), or the like.

The information collecting unit 110 may collect operation information of the inverter 10 that drives the motor 30. [ Here, the operation information may include any information relating to the operation of the inverter 10, and may include, for example, a DC link voltage V _DC stored in the DC link capacitor C _DC constituting the inverter 10, The switching frequency f _SW of the motor 30, the speed f _{M of the} motor 30 and the output current I _M output to the motor 30, the power factor, the modulation index of the PWM signal, .

More specifically, the information collecting unit 110 can collect the DC link voltage (V _DC ) from the voltage sensor S1 that detects the voltage across the DC link capacitor C _DC and controls the inverter control unit 140 The switching frequency f _SW can be collected. The information collecting unit 110 may collect the speed f _M of the motor 30 from a hall sensor (not shown) provided in the motor 30 and may collect the speed f _M of the current sensor S2). ≪ / RTI >

The loss calculating section 120 can calculate the power loss of the power module 11 constituting the inverter 10 based on the collected operation information.

Power loss may occur in the power module 11 as the IGBT included in the power module 11 performs the turn-on and turn-off operations. More specifically, since the IGBT is turned on or off only for a predetermined period of time, power loss (switching loss) due to switching may occur, and the power loss due to the resistance component existing in the device as the current flows (Conduction loss) may occur.

Such a power loss as it affects the temperature of the IGBT, prior to calculating a junction temperature of the later IGBT (T _j), section 120, first loss calculation can calculate the power dissipation of the IGBT and the diode, respectively.

Power loss of the IGBT (P _IGBT) is a switching loss in the _IGBT (P _{SW, IGBT),} may include a conduction loss (P _{COND, IGBT)} of the IGBT, the power loss of the diode (P _DIODE) is a switching of the diode losses ( P _{SW, DIODE} ) and a diode conduction loss (P _{COND, DIODE} ).

In other words, the power loss of the power modules _{(11) (P IGBT, MODULE} ) the switching losses of the IGBT (P _{SW, IGBT),} the conduction loss of the IGBT (P _{COND, IGBT),} the switching loss of the diode (P _{SW, DIODE)} And the conduction loss (P _{COND, DIODE} ) of the _diode .

The loss calculation section 120 calculates the loss current I _IGBT flowing through the _IGBT , the output current I _M output to the motor 30, the turn-on loss (E _ON ) and the turn-off loss (E _OFF ) The switching loss (P _{SW, IGBT} ) of the _IGBT can be calculated by using at least one of R _G , DC link voltage V _DC , and switching frequency f _SW .

The loss calculator 120 calculates the loss I _IGBT , the collector-emitter saturation voltage V _CE (sat), the collector-emitter saturation resistance R _CE , (P _{COND, IGBT} ) of the _IGBT can be calculated using at least one of the output current (I _M ) output to the inverter (30), the modulation index of the PWM signal, and the power factor.

Meanwhile, the loss calculation unit 120 calculates the loss current I _M , the switching frequency f _SW , the diode turn-off loss E _rec , the DC link voltage V _DC , the rating of the diode The switching loss (P _{SW, DIODE} ) of the _diode can be calculated using at least one of the voltage (V _nom ) and the rated current (I _nom ).

The loss calculation section 120 calculates the loss V _DIODE across the diode, the current I _DIODE flowing through the diode, the conduction resistance R _DIODE generated when the diode conducts, The conduction loss (P _{COND, DIODE} ) of the _diode can be calculated by using at least one of the current I _M , the modulation index of the PWM signal, and the power factor.

Loss calculator 120, the power module 11 of the power loss current flowing through the IGBT of the parameters for calculating the (P _{IGBT, MODULE)} (I _IGBT), voltage (V _DIODE) applied to the diodes at both ends, passing through the diode The current I _DIODE , the DC link voltage V _DC , the output current I _M output to the motor 30, the switching frequency f _SW , the power factor, and the modulation index of the PWM signal, And may be provided from the collecting unit 110.

On the other hand, the loss calculation unit 120 calculates the loss (E _ON ) and turn-off loss (E _OFF ) of the IGBT among the parameters for calculating the power loss (P _{IGBT , MODULE} ) (R _G), a collector-emitter saturation (collector-emitter saturation) voltage (V _CE (sat)), the collector-emitter saturation resistance (R _CE), diode turn-off losses (E _rec), the rated voltage of the diode ( V _nom ), the rated current I _nom , and the conduction resistance R _DIODE that occurs during diode conduction from the above-described memory 150.

Power loss of the IGBT (P _IGBT) and the power loss calculation method of (P _DIODE) of the diode may further use other parameters outside the above-mentioned parameters, the power loss of the power loss (P _IGBT) and diode in the IGBT (P _DIODE) Can be calculated by various formulas commonly used in the art.

The junction temperature calculating unit 130 calculates the junction temperature T _j of the power module 11 based on the power loss calculated by the loss calculating unit 120 and the thermal coefficient of resistivity of the power module 11 ) Can be calculated.

More specifically, the junction temperature calculating unit 130 can calculate the junction temperature T _j using the following equation (1).

(T _j is the junction temperature of the power module 11, T _s is the temperature measured at the temperature sensor 210, P _{IGBT, MODULE} is the power loss of the power module 11, R _th is the thermal resistance coefficient)

Here, the thermal resistance coefficient R _th is expressed in [ ^o C / W] and can represent a temperature ( ^o C) required for the unit heat quantity W to be conducted between the IGBT and the temperature sensor 210.

The detailed construction of the power module 11 will be described below with reference to FIG. 3 in order to more specifically describe the process of calculating the thermal resistance coefficient R _th and the junction temperature T _j using the same.

3, the power module 11 includes a substrate 311, a switching module 310 including a plurality of IGBTs formed on the substrate 311, and a switching module 310 coupled to the switching module 310, And a heat sink 320 that absorbs heat.

The substrate 311 can provide a switching signal output from the inverter control unit 140 to be described later to the IGBT. To this end, the substrate 311 may include a circuit board for providing an electrical signal to the IGBT.

More specifically, the substrate 311 may include a base plate 311a and a printed circuit board (PBC) 311b formed on the base plate. A circuit for electrically connecting the IGBT and the inverter control unit 140 may be formed on the printed circuit board 311b.

The printed circuit board 311b may be a ceramic substrate deposited on the base plate 311a. The printed circuit board 311b may be directly deposited on the base plate 311a by a direct bonding copper (DBC) method.

The heat sink 320 may be coupled to the substrate 311 of the switching module 310 to absorb heat.

As described above, when the IGBT included in the power module 11 repeats turn-on and turn-off operations, a power loss occurs in the corresponding IGBT, and such power loss can be released as heat.

As the heat sink 320 is fastened to the substrate 311 of the switching module 310, heat emitted from the IGBT can be transferred to the heat sink 320 through the substrate 311 described above.

A coolant passage 320a may be provided in the heat sink 320 and a coolant flowing in the coolant passage 320a may absorb heat transmitted to the heat sink 320. [

In order to increase the heat conduction between the IGBT and the heat sink 320, a material having a high thermal conductivity may be applied to a portion where the switching module 310 and the heat sink 320 are coupled. For example, a thermal grease 311c may be applied between the switching module 310 and the heat sink 320.

The temperature sensor 210 is installed at an arbitrary position (measurement point) of the power module 11 shown in FIG. 3, and can measure the temperature of the measurement point.

In one example, the temperature sensor 210 may be a thermistor formed on the substrate 311 and connected to the substrate 311. The thermistor is a resistor including a semiconductor whose resistance varies with temperature, and may be connected to the substrate 311 to have resistance according to the temperature of the substrate 311. [

More specifically, the thermistor may be a negative temperature coefficient (NTC) thermistor having a resistance inversely proportional to the temperature of the substrate 311, and may be a positive temperature coefficient (PTC) thermistor having a resistance proportional to the temperature of the substrate 311 have.

The junction temperature calculating unit 130 can calculate the temperature according to the resistance of the thermistor. More specifically, the junction temperature calculating unit 130 can refer to a data sheet of a thermistor stored in advance in the memory 150 to check the temperature corresponding to the measured resistance.

The temperature information corresponding to the resistance included in the data sheet can be determined by the device characteristics of the thermistor, and the data sheet can be provided from the manufacturer of the thermistor.

On the other hand, since the temperature measured by the thermistor is the temperature of the heat emitted from the IGBT and transmitted through the medium such as the substrate 311, the temperature measured by the thermistor may differ from the junction temperature T _j .

The junction temperature calculating unit 130 calculates the junction temperature of the power module 11 based on the resistance of the thermistor, the power loss (P _{IGBT, MODULE} ) of the power module 11 and the thermal resistance coefficient R _th between the IGBT and the thermistor The junction temperature T _j can be calculated.

More specifically, the temperature T _s measured by the temperature sensor 210 in the above-described equation (1) may be a temperature calculated based on the resistance of the thermistor.

In addition, pre-by Equation 1] IGBT and the thermal resistance coefficient between the thermistor (R _th) is to first design the power module 11, the medium between the IGBT and the thermistor (for example, substrate 311) in the And stored in the memory 150 in advance.

The junction temperature calculation unit 130 calculates the junction temperature _Tx of the IGBTs stored in the memory 150 and the temperature T _s calculated based on the resistance of the thermistor and the power loss P _{IGBT and MODULE} calculated by the loss calculation unit 120 The junction temperature T _j of the power module 11 can be calculated by applying the thermal resistance coefficient R _th between the thermistors to Equation (1).

In another example, the temperature sensor 210 may measure the temperature of the heat sink 320 at any measurement point formed in the heat sink 320. At this time, the temperature sensor may be a thermistor, but a detailed description of the thermistor has been described above, so that further explanation will be omitted here.

The temperature measured by the heat sink 320 may be different from the junction temperature T _{j since the} temperature measured by the heat sink 320 is the temperature of the heat emitted from the IGBT and transmitted through the substrate 311.

Accordingly, the junction temperature calculation unit 130 calculates the junction temperature of the heat sink 320, the power loss (P _{IGBT , MODULE} ) of the power module 11, and the thermal resistance coefficient R _th between the IGBT and the heat sink 320 The junction temperature T _j of the power module 11 can be calculated on the basis of the calculated junction temperature T _j .

More specifically, the temperature T _s measured by the temperature sensor 210 in the above-described formula (1) may be the temperature of the heat sink 320.

On the other hand, the thermal resistance coefficient _Rth between the IGBT and the heat sink 320 can be calculated using the following equation (2).

(R _th is the thermal resistance coefficient between the IGBT and the heat sink 320, the heat resistance coefficient, R _js is the thermal resistance coefficient between the IGBT and the substrate 311, R _sh is the substrate 311 and the heat sink 320 between)

The thermal resistance coefficient R _js between the IGBT and the substrate 311 in Equation 2 and the thermal resistance coefficient R _sh between the substrate 311 and the heat sink 320 are used to design the power module 11 for the first time And may be stored in memory 150 in advance.

The junction temperature calculation unit 130 calculates the junction temperature Tx of the IGBT and the heat sink Tx calculated based on the power loss (P _{IGBT, MODULE} ), the temperature of the heat sink (T _S ) and the memory 150 calculated by the loss calculation unit 120, The junction temperature T _j of the power module 11 can be calculated by applying the thermal resistance coefficient R _th between the power module 320 and the power module 320 to Equation (1).

On the other hand, when the above-described thermal resistance coefficient R _th is not stored in the memory 150 in advance, the junction temperature calculation unit 130 calculates the junction temperature T _{j , m} based on the actual junction temperature T _{j , m} of the IGBT _, ( _Rth ) of the heat resistance coefficient ( _Rth ) can be calculated.

More specifically, the junction temperature calculating unit 130 can calculate the thermal resistance coefficient R _th using the following equation (3).

(R _th is the thermal resistance coefficient of the power module 11, T _{j, m} is the measured junction temperature, T _S is the temperature, P _{IGBT, MODULE} is the power loss of the power module 11 measured by the temperature sensor 210)

The actual junction temperature ( _{Tj , m} ) can be measured by at least one of a thermocouple and an infrared camera.

A thermocouple is a temperature sensor that measures the temperature of an object to be measured by measuring an electromotive force generated by a temperature difference between a junction of one end of a metal wire and a junction of the other end.

4 showing a top view of the power module 11 shown in FIG. 3, a plurality of IGBTs and a temperature sensor 210 (for example, a thermistor) are formed on a substrate 311 .

The TC module 410 is a module including a thermocouple temperature sensor. A metal wire connected to the TC module 410 can be connected to an object having a reference temperature in the TC module 410 at one end 412, 411) may be bonded to the IGBT. The TC module 410 can measure the electromotive force generated by the temperature difference between the reference temperature and the IGBT, and can measure the temperature of the IGBT based on the measured electromotive force.

An infrared camera is a temperature sensor that measures the temperature of an object to be measured by receiving infrared light emitted at a different wavelength depending on the temperature of the object to be measured.

The infrared camera can photograph the top surface of the power module 11 shown in FIG. 4, and each object in the photographed image can be represented by a different color according to the wavelength of infrared rays radiated by the infrared camera.

The junction temperature of the IGBT may be measured by at least one of the color expressed in the image photographed by the infrared camera and the wavelength of the emitted infrared light.

When the junction temperature of the IGBT is actually measured, the junction temperature calculation unit 130 applies the actual junction temperature T _{j , m} to the above-described expression (3) to calculate the thermal resistance coefficient R _th ) Can be calculated.

On the other hand, the thermal resistance coefficient R _th may vary depending on the temperature of the refrigerant and the flow rate of the refrigerant. The flow rate of the refrigerant can be controlled by a separate refrigerant amount controller (not shown). In general, the temperature of the refrigerant and the flow rate of the refrigerant can be proportional. In other words, as the temperature of the refrigerant decreases, the flow rate of the refrigerant decreases, and as the temperature of the refrigerant increases, the flow rate of the refrigerant may increase.

As the flow rate of the refrigerant increases, the rate of absorption of heat generated by the IGBT increases. As the flow rate of the refrigerant increases, the thermal resistance coefficient R _th decreases. As the flow rate of the refrigerant decreases, the thermal resistance coefficient R _th increases . In other words, the flow rate of the refrigerant and the thermal resistance coefficient ( _Rth ) can be inversely proportional.

Accordingly, the junction temperature calculation unit 130 can correct the thermal resistance coefficient R _th by applying the thermal resistance compensation coefficient according to at least one of the temperature of the refrigerant and the flow rate of the refrigerant.

More specifically, the junction temperature calculation unit 130 can check the temperature of the refrigerant through a separate temperature measurement module for measuring the temperature of the refrigerant. In addition, the junction temperature calculation unit 130 can calculate the flow rate of the refrigerant based on the speed of the pump controlled by the refrigerant amount controller, or check the flow rate of the refrigerant through the flow rate sensor or the like.

In the memory 150, the heat resistance correction ratio corresponding to the temperature of the coolant and the flow rate of the coolant may be stored in advance in the form of a lookup table (LUT) or the like. The junction temperature calculation unit 130 refers to the memory 150 to check the heat resistance correction ratio corresponding to the temperature of the refrigerant and the flow rate of the refrigerant and sets the determined heat resistance correction ratio to the existing heat resistance coefficient _Rth It is possible to correct the thermal resistance coefficient R _th .

The junction temperature calculating unit 130 may calculate the junction temperature T _j by applying the corrected thermal resistance coefficient R _th and calculate the junction temperature T _j using the thermal resistance coefficient R _th The method of doing so has been described above, so a detailed explanation will be omitted.

Referring again to FIG. 2, the inverter control unit 140 may provide a switching signal to each of the IGBTs included in the power module 11. For this, the inverter control unit 140 may include at least one gate driver (not shown).

In other words, the inverter control unit 140 can control the turn-on and turn-off of each IGBT through the switching signal, and can provide the switching signal to the IGBT through a pulse width modulation (PWM) scheme .

On the other hand, the IGBT can operate normally within a certain range of temperatures, and the maximum temperature of a certain range of temperatures can be defined as a critical temperature. In other words, the threshold temperature may be the maximum temperature at which the IGBT can operate normally based on the device characteristics of the IGBT.

Inverter control unit 140 the control unit if the junction temperature (T _j) is more than the limit temperature calculated by the junction temperature calculation unit 130 may stop the driving of the inverter 10.

More specifically, the inverter control unit 140 compares the calculated junction temperature T _j with the threshold temperature stored in the memory 150, and when the junction temperature T _j is determined to be equal to or higher than the threshold temperature, The switching signal can be cut off.

As the switching signal is interrupted, the IGBT no longer performs a turn-on or turn-off operation, so that the drive of the inverter 10 can be stopped.

Further, the drive control unit 140 when the junction temperature calculated by the temperature calculation junction portion (130) (T _j) is over temperature protection is less than the limit temperature can limit the driving of the inverter 10.

Referring to FIG. 5, the protection temperature may be previously stored in the memory 150 by setting the ratio of the limit temperature within a certain range of temperatures at which the IGBT can operate normally. For example, the protection temperature may be set to 80% of the critical temperature.

The inverter control unit 140 compares the calculated junction temperature T _j with the protection temperature and the limit temperature stored in the memory 150 and provides the junction temperature T _j to the IGBT when it is determined that the junction temperature T _j is equal to or higher than the protection temperature, The driving of the inverter 10 can be restricted by controlling the switching signal.

More specifically, the inverter control unit 140 can reduce the power loss of the power module 11 by limiting the drive of the inverter 10 through the control of the switching signal provided to the IGBT. When the power loss of the power module 11 is lowered, the junction temperature T _j can be lowered according to the above-mentioned equation (1).

That is, the inverter control unit 140 may limit the drive of the inverter 10 to lower the junction temperature T _j if the calculated junction temperature T _j is above the protection temperature and below the limit temperature.

When the speed f _M of the motor 30 driven by the inverter 10 is equal to or higher than the reference speed in restricting the drive of the inverter 10 by the inverter control unit 140, the inverter control unit 140 sets the discontinuous pulse width It is possible to limit the drive of the inverter 10 through Discontinuous Pulse Width Modulation (DPWM).

The speed f _M of the motor 30 can be collected by the information collecting unit 110 as described above. The inverter control unit 140 can compare the speed f _M of the collected motor 30 with the reference speed stored in the memory 150.

The reference speed may be set to an arbitrary speed by a user, for example, may be set to an integer multiple of the switching frequency (f _SW) of the IGBT, 9 of More specifically, the switching frequency (f _SW) of the IGBT Times.

As a result of the comparison, if the speed f _M of the motor 30 is equal to or higher than the reference speed, the inverter control unit 140 can provide a switching signal applying the discontinuous pulse width modulation (DPWM) method to the power module 11.

More specifically, the inverter control unit 140 can reduce the switching frequency of the IGBT by providing the power module 11 with the switching signal applying the discontinuous pulse width modulation (DPWM) method.

For example, the drive control unit 140 may provide a switching signal for modulation (DPWM) 60 discontinuity pulse width ^o the inverter 10. In this case, the command voltage included in the switching signal may include a switching discontinuity interval of 60 ^degrees around the maximum and minimum points of the phase voltage signal.

Therefore, the command voltage is fixed to the positive DC voltage value in the switching discontinuity section corresponding to the 60 ^° phase around the maximum point. In the switching discontinuity section corresponding to the 60 ^° phase around the minimum point, the command voltage is negative It can be fixed to a DC voltage value.

Since the switching operation of the IGBT does not occur in the switching discontinuity section, when the inverter 10 is driven in accordance with the switching signal, the number of switching times of the IGBT decreases, and the switching loss (P _{SW, IGBT} ) can do.

If the speed f _M of the motor 30 driven by the inverter 10 is less than the reference speed in restricting the drive of the inverter 10 by the inverter control unit 140, The switching frequency of the inverter 10 can be reduced to limit the drive of the inverter 10.

More specifically, in generating the switching signal for the pulse width modulation (PWM), the inverter control unit 140 decreases the frequency of the carrier signal for determining the frequency of the switching signal, thereby reducing the frequency of the switching signal .

For example, the inverter control unit 140 can reduce the frequency of the carrier signal by 10% from the frequency of the existing carrier signal. Accordingly, the frequency of the switching signal for pulse width modulation (PWM) can also be reduced by 10%.

The IGBT performs the switching operation, in the case of driving the inverter 10 in accordance with the switching signal frequency decreases, the switching frequency of the IGBT decreases, and accordingly, the above-described switching loss (P _{SW, IGBT)} according to a switching signal Can be reduced.

Since the switching loss (P _{SW , IGBT} ) of the _IGBT decreases, the junction temperature (T _j ) decreases. Therefore, a detailed description will be omitted here.

Hereinafter, a method of driving an inverter according to an embodiment of the present invention will be described in detail with reference to FIG. 5 to FIG.

FIG. 6 is a flowchart illustrating an inverter driving method according to an embodiment of the present invention. FIG. 7 is a flowchart illustrating a method of determining an operation mode according to a junction temperature and driving an inverter according to an operation mode.

6 and 7 can be performed by the inverter driving apparatus 100 shown in FIG. 1, and the respective components of the inverter driving apparatus 100 have been described above, .

Referring to FIG. 6, an inverter driving method according to an embodiment of the present invention includes collecting operation information of an inverter that drives a motor (S110), calculating a power of the power module constituting the inverter based on the collected operation information Calculating a junction temperature of the power module based on the calculated power loss and the thermal resistance coefficient of the power module, comparing the calculated junction temperature with the protection temperature and the limit temperature, (S140) of determining an operation mode of the inverter, and driving the inverter according to an operation mode of the inverter (S150).

The operation information collection in step S110, the calculation of the power loss (P _{IGBT , MODULE} ) in step S120 and the calculation of the junction temperature T _{j in} step S130 have been described with reference to Figs. 1 to 4, Steps S140 and S150 will be mainly described.

The inverter driving apparatus 100 can determine the operation mode of the inverter by comparing the junction temperature with the protection temperature and the limit temperature (S140).

Here, the threshold temperature is set to be higher than the protection temperature and can be set to the maximum temperature at which the IGBT in the power module can normally be driven.

Referring to FIG. 5, the IGBT can operate within the maximum current (limiting current) that can flow in the IGBT, and can operate in the junction temperature range within the limit temperature.

At this time, the inverter driving apparatus 100 may further set a protection temperature lower than the threshold temperature, and compare the calculated junction temperature T _j with the protection temperature and the threshold temperature to determine the operation mode of the inverter.

The inverter driving apparatus 100 can determine the operation mode as the normal operation mode when the junction temperature T _j is less than the protection temperature. In addition, the inverter driving apparatus 100 can determine the operation mode as the limited operation mode when the junction temperature T _j is equal to or higher than the protection temperature and lower than the limit temperature. In addition, the inverter driving apparatus 100 can determine the operation mode as the drive stop mode if the junction temperature T _j is equal to or higher than the limit temperature.

More specifically, referring to FIG. 7, the inverter driving apparatus 100 can compare the junction temperature T _j with the protection temperature (S 141).

As a result of comparison, if the junction temperature T _j is less than the protection temperature, the operation mode can be determined as the normal operation mode (S143). On the other hand, the junction temperature (T _j) is (S142) the junction temperature (T _j) is above protection temperature can be compared with the limit temperature.

As a result of the comparison, if the junction temperature T _j is equal to or higher than the limit temperature, the operation mode can be determined as the drive stop mode (S144). On the other hand is in, to determine the junction temperature (T _j) is less than the limit temperature operation mode to the limited operation mode (S145).

When the operation mode is determined, the inverter driving apparatus 100 can drive the inverter according to each operation mode (S150).

More specifically, referring to FIG. 7, when the operation mode is the normal operation mode, the inverter driving apparatus 100 can drive the inverter according to the conventional command voltage (S151).

When the operation mode is the drive stop mode, the inverter drive apparatus 100 can stop the drive of the inverter by interrupting the switching signal provided to the power module (S152).

When the operation mode is the limited operation mode, the inverter driving apparatus 100 can compare the speed f _M of the motor with the reference speed (S 153). Since the reference speed has been described above, a detailed description thereof will be omitted.

As a result of comparison, when the motor speed f _M is equal to or higher than the reference speed, discontinuous pulse width modulation (DPWM) is performed on the switching signal provided to the power module (S154) to drive the inverter.

As described above, the number of switching times of the IGBT is reduced through the discontinuous pulse width modulation (DPWM), and the power loss (P _{IGBT, MODULE} ) of the power module can be reduced.

Conversely, if the motor speed f _M is less than the reference speed, the switching frequency of the inverter is decreased (S155) to drive the inverter.

As described above, the switching frequency of the IGBT is reduced through reduction of the switching frequency, and thus the power loss (P _{IGBT, MODULE} ) of the power module can be reduced.

If the power loss (P _{IGBT , MODULE} ) of the power module is reduced, the junction temperature T _j can be reduced by the above-mentioned equation (1).

That is, in the inverter driving method of the present invention, when the junction temperature of the power module is increased and the operation mode of the inverter is determined to be the limited operation mode, the junction temperature can be lowered by limiting the drive of the inverter.

As described above, the present invention can reduce the junction temperature by restricting the drive of the inverter according to the junction temperature, and thereby, the inverter can be continuously driven.

Further, in restricting the drive of the inverter, the present invention can drive the inverter efficiently while lowering the junction temperature by restricting the drive of the inverter in other ways according to the speed of the motor.

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, But the present invention is not limited thereto.

Claims (15)

An information collecting unit for collecting operation information of an inverter for driving a motor;
A loss calculation unit for calculating a power loss of the power module constituting the inverter based on the collected operation information;
A junction temperature calculation unit for calculating a junction temperature of the power module based on the calculated power loss and a thermal resistance coefficient of the power module; And
And an inverter control unit for limiting the drive of the inverter when the calculated junction temperature is equal to or higher than the protection temperature and lower than the limit temperature
Inverter drive device.
The method according to claim 1,
The power module
A switching module including the substrate, the IGBT formed on the substrate,
And a heat sink coupled to the switching module to absorb heat generated in the IGBT.
3. The method of claim 2,
The switching module
And a thermistor formed on the substrate and connected to the substrate.
The method according to claim 1,
The information collecting unit
And to collect at least one of a DC link voltage, a switching frequency, a speed of the motor, and an output current of the inverter.
3. The method of claim 2,
The junction temperature calculation unit
Wherein the junction temperature of the power module is calculated based on the temperature of the heat sink, the power loss, and the thermal resistance coefficient between the IGBT and the heat sink.
The method of claim 3,
The junction temperature calculation unit
And calculates the junction temperature of the power module based on the resistance of the thermistor, the power loss, and the thermal resistance coefficient between the IGBT and the thermistor.
The method according to claim 1,
The junction temperature calculation unit
Wherein the thermal resistance coefficient is corrected by applying a thermal resistance compensation coefficient according to at least one of a temperature of the refrigerant and a flow rate of the refrigerant.
The method according to claim 1,
The junction temperature calculation unit
And calculates the thermal resistance coefficient of the power module based on the actual junction temperature of the IGBT.
The method according to claim 1,
The inverter control unit
And stops driving the inverter when the calculated junction temperature is equal to or higher than the limit temperature.
The method according to claim 1,
The inverter control unit
And an inverter driving device (100) for limiting driving of the inverter through discontinuous pulse width modulation (DPWM) if the calculated junction temperature is equal to or higher than the protection temperature and less than the limit temperature, .
The method according to claim 1,
The inverter control unit
Wherein when the calculated junction temperature is equal to or higher than the protection temperature and less than the limit temperature, the switching frequency of the inverter is reduced to limit the drive of the inverter if the speed of the motor is less than the reference speed.
Collecting operation information of the inverter driving the motor;
Calculating a power loss of the power module constituting the inverter based on the collected operation information;
Calculating a junction temperature of the power module based on the calculated power loss and a thermal resistance coefficient of the power module;
Determining an operation mode of the inverter by comparing the calculated junction temperature with a protection temperature and a limit temperature; And
And driving the inverter in accordance with an operation mode of the inverter
Drive method.
13. The method of claim 12,
Determining the operation mode of the inverter by comparing the calculated junction temperature with a protection temperature and a limit temperature set larger than the protection temperature
Determines the operation mode of the inverter as the normal operation mode when the junction temperature is lower than the protection temperature and determines the operation mode of the inverter as the limited operation mode if the junction temperature is the protection temperature and is lower than the limit temperature, And determining the operation mode of the inverter as the drive stop mode when the junction temperature is equal to or higher than the limit temperature.
13. The method of claim 12,
The step of driving the inverter according to the operation mode of the inverter
And driving the inverter through a Discontinuous Pulse Width Modulation (DPWM) if the operation mode of the inverter is the limited operation mode and the speed of the motor is equal to or greater than the reference speed.
13. The method of claim 12,
The step of driving the inverter according to the operation mode of the inverter
And driving the inverter by reducing the switching frequency of the inverter when the speed of the motor is less than the reference speed when the operation mode of the inverter is the limited operation mode.

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