JP6143566B2 - Power converter and air conditioner using the same - Google Patents

Description

  The present invention relates to a power conversion device that converts electric power supplied from a commercial power source to a motor such as a compressor or a fan.

  As a large-capacity inverter device for driving a motor such as a compressor or a fan of a refrigeration air conditioner, a method of generating a DC voltage for driving an inverter by a three-phase full-wave rectifier circuit is used. In a refrigerated air conditioner, in order to increase energy consumption efficiency (COP) in rated operation, a motor for a compressor tends to be designed to have the same output voltage as the power supply voltage in the vicinity of the rated rotational speed. At this time, during an overload operation in which the motor is operated in a high-speed rotation range exceeding the rated rotation speed of the motor, the output current increases due to the output voltage saturation of the inverter circuit, and the motor efficiency and the inverter efficiency decrease.

  In view of this, a power converter having a booster circuit has been proposed in order to drive the motor with high efficiency (see, for example, Patent Document 1). In Patent Document 1, a booster circuit including a reactor, a backflow prevention diode, and a switching element is provided between the rectifier circuit and the inverter circuit, and the booster circuit boosts the DC voltage rectified by the rectifier circuit. Is disclosed. In the booster circuit, energy is accumulated in the reactor during the on period of the switching element, and the energy accumulated during the off period is released to boost the output voltage. The output voltage from the booster circuit is controlled by the time during which the switching element is turned on (on duty). By controlling the on-duty of the switching element of the booster circuit, the voltage applied to the motor is increased, and the efficiency can be improved and the motor operation area can be expanded by suppressing the motor current.

  The reactor has a property of direct current superimposition in which the inductance component varies depending on the magnitude of the flowing current. When an excessive current flows through the reactor, a phenomenon called magnetic saturation occurs in which the inductance component decreases rapidly. When magnetic saturation occurs in the reactor, a desired inductance may not be obtained, and an abnormality may occur in the boosting operation. Therefore, it has been proposed to automatically detect an abnormality caused by magnetic saturation of the reactor (see, for example, Patent Document 2). Patent Document 2 discloses detecting magnetic saturation of a reactor based on an inductance component of the reactor or a reactor temperature. When the magnetic saturation occurs in the reactor, the operation of the entire apparatus is stopped.

JP 2012-196142 A JP 2008-99518 A

  However, as in Cited Document 2, if the entire apparatus is stopped when magnetic saturation occurs, there is a problem that the utilization factor of the apparatus receiving power supply is reduced. On the other hand, if the operation is continued as it is when magnetic saturation occurs, an overcurrent cutoff circuit may be activated and an apparatus such as a compressor may be abnormally stopped, or an element or the like may be destroyed due to overcurrent.

  The present invention has been made to solve the above-described problems, and determines in advance the possibility that magnetic saturation will occur, and a power converter that can continue operation without causing the apparatus to stop abnormally. It aims at providing the air conditioning apparatus using this.

The power conversion device of the present invention includes a rectifier that rectifies an AC voltage supplied from an AC power supply, a reactor, a switching element, and a backflow prevention element, a transformer circuit that transforms an output voltage from the rectifier, and a transformer circuit. A smoothing capacitor that smoothes the output of the inverter, an inverter circuit that converts the DC voltage smoothed by the smoothing capacitor into an AC voltage, a reactor current detection unit that detects a reactor current flowing through the reactor of the transformer circuit, and a reactor current detection unit Based on the detected reactor current, the on-period of the switching signal for driving the switching element of the transformer circuit is controlled, and the transformer control means for controlling the operation of the transformer circuit is provided. An inductor that estimates the inductance component of a reactor from the amount of current change over a specified period A scan estimating means, and the estimated inductance component is equal to or smaller than the threshold in the inductance estimation means, if the current threshold is greater than the reactor current is preset abnormality determining that there is a possibility that abnormality occurs in the reactor And a switching signal control unit that adjusts an ON period of the switching signal so that the reactor current is suppressed when the abnormality determination unit determines that there is a possibility that an abnormality may occur in the reactor. .

  According to the power conversion device of the present invention, when it is determined that there is a possibility that an abnormality may occur in the reactor, the operation of the transformer circuit is limited and the operation is continued, thereby efficiently preventing the device from abnormally stopping. The apparatus can be operated, and further, an element having a small short-circuit resistance can be applied to the booster circuit.

It is a circuit diagram which shows Embodiment 1 of the power converter device of this invention and an air conditioning apparatus using the same. It is a block diagram which shows an example of the transformation control means in the power converter device of FIG. It is a flowchart which shows the operation example of the transformation control means in the power converter device of FIG. It is a graph which shows an example of the reactor electric current which flows into the reactor of FIG. It is a block diagram which shows Embodiment 2 of the power converter device of this invention. It is a block diagram which shows an example of the transformation control means in the power converter device of FIG. It is a flowchart which shows the operation example of the transformation control means in the power converter device of FIG.5 and FIG.6. It is a block diagram which shows Embodiment 3 of the power converter device of this invention. It is a graph which shows an example of the electric current which flows into a reactor, and an inductance characteristic. It is a block diagram which shows Embodiment 4 of the air conditioning apparatus and power converter device of this invention. It is a block diagram which shows Embodiment 5 of the air conditioning apparatus and power converter device of this invention.

Embodiment 1. FIG.
Hereinafter, embodiments of a power converter of the present invention and an air conditioner using the same will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a preferred embodiment of a power converter of the present invention and an air conditioner using the same, and the power converter 1 and the air conditioner 100 will be described with reference to FIG. The power conversion device 1 converts the power supplied from the three-phase AC power supply 6 and rotationally drives the motor (load) of the compressor 2 in the air conditioner 100. Moreover, the air conditioning apparatus 100 comprises the refrigerant circuit which connected the compressor 2, the condenser 3, the expansion means 4, and the evaporator 5 with refrigerant | coolant piping.

  The power conversion device 1 includes a three-phase rectifier 10, a transformer circuit 20, a smoothing capacitor 30, and an inverter circuit 40. The three-phase rectifier 10 converts an AC voltage (for example, AC 200 V) of the three-phase AC power source 6 into a DC voltage, and includes, for example, a three-phase full-wave rectifier in which six diodes are bridge-connected.

  The transformer circuit 20 is a booster circuit (boost chopper circuit) that transforms the output voltage (DC voltage) from the three-phase rectifier 10 to, for example, DC 350 V, and includes a reactor 21, a switching element 22, and a backflow prevention element 23. Yes. The switching operation of the switching element 22 is controlled by a predetermined on-duty switching signal SS output from the transformation control means 70. Note that the switching element 22 and the backflow prevention element 23 are made of, for example, a wide band gap semiconductor such as a silicon carbide (SiC) element, a gallium nitride (GaN), or a diamond element having a larger band gap than a silicon (Si) element. Can be configured. In addition to the wide band gap semiconductor, a semiconductor element such as MOFET or IGBT may be used as the switching element 22, and an element such as a fast recovery diode may be used as the backflow prevention diode.

  The smoothing capacitor 30 smoothes and charges the output from the transformer circuit 20. The inverter circuit 40 converts the DC power smoothed and charged by the smoothing capacitor 30 into AC power (PWM voltage), and includes a plurality of switching elements such as IGBTs. Note that, as the switching element of the inverter circuit 40, a wide band gap semiconductor such as a silicon carbide (SiC) element may be used in the same manner as the switching element 22 described above. The inverter circuit 40 is connected to a load M such as a motor of the compressor 2 of the air conditioner 100 and supplies an alternating current having a predetermined frequency to the load M.

  Further, the power conversion device 1 includes an output voltage detection unit 51, a motor current detection unit 52, and a reactor current detection unit 53. The output voltage detector 51 detects the output voltage (DC bus voltage) Vout of the transformer circuit 20 by measuring the voltage of the smoothing capacitor 30, and the motor current detector 52 detects the motor of the compressor 2 from the inverter circuit 40. The current supplied to is detected. Reactor current detection unit 53 detects reactor current IL flowing through reactor 21, and for example, detects reactor current IL flowing through reactor 21 at a constant period synchronized with the peak (peak or valley) of the carrier signal. It has become.

  Furthermore, the power conversion apparatus 1 includes an inverter control unit 60 that controls the operation of the inverter circuit 40 and a transformation control unit 70 that controls the operation of the transformer circuit 20. The inverter control means 60 and the transformation control means 70 are comprised from microcomputers, such as DSP, for example. Based on the output voltage Vout detected by the output voltage detector 51 and the motor current detected by the motor current detector 52, the inverter control means 60 is an inverter circuit that drives the compressor 2 to rotate at a desired rotational speed. 40 is controlled (PWM control). Specifically, the inverter control means 60 performs coordinate conversion on the detection signal of the motor current detection unit 52, obtains a voltage command value by performing current control, and after the coordinate conversion of this command value, each inverter circuit 40 A drive signal (PWM signal) for operating the switching element is generated. Then, the inverter control means 60 adjusts the frequency of the output voltage of the inverter circuit 40 so as to obtain a desired refrigeration capacity, and controls the rotational speed of the compressor 2.

  The transformation control means 70 controls the operation of the switching element 22 so as to obtain a desired output voltage based on the output voltage Vout detected by the output voltage detector 51 and the reactor current IL detected by the reactor current detector 53. . The transformer control means 70 starts the control operation of the transformer circuit 20 when the load (motor) M of the compressor 2 is in a driven state, that is, when the inverter circuit 40 is operating. 20 is in a stopped state.

  Next, an operation example of the power conversion apparatus 1 will be described with reference to FIG. First, an AC voltage is supplied from the three-phase AC power source 6 to the three-phase rectifier 10 and is rectified to a DC voltage by the three-phase rectifier 10. Thereafter, the rectified DC voltage is boosted in the transformer circuit 20. In the transformer circuit 20, when the switching element 22 is turned on, the backflow prevention element 23 is prevented from conducting, and the voltage rectified by the three-phase rectifier 10 is applied to the reactor 21. On the other hand, when the switching element 22 is turned off, the backflow prevention element 23 is conducted, and a voltage in the direction opposite to that when the switching element 22 is turned on is induced in the reactor 21. At this time, from the viewpoint of energy, it can be seen that the energy accumulated in the reactor 21 when the switching element 22 is turned on is transferred to the inverter circuit 40 which is a load when the switching element 22 is turned off. Therefore, the output voltage Vout of the transformer circuit 20 can be controlled by controlling the on-duty of the switching element 22.

  Here, when an excessive current flows through the reactor 21 during the operation of the power conversion device 1 described above, a phenomenon of magnetic saturation in which the inductance component L rapidly decreases occurs. When magnetic saturation occurs in the reactor 21, a desired inductance may not be obtained, and an abnormality may occur in the boosting operation. Therefore, the transformation control means 70 has a function of determining whether or not an abnormality has occurred in the reactor 21 and performing control to limit the operation of the transformation circuit 20 when the abnormality has occurred. .

  FIG. 2 is a block diagram showing an example of the transformation control means 70. The transformation control means 70 will be described with reference to FIGS. The transformation control means 70 in FIG. 2 includes a current change amount calculation means 71, an inductance estimation means 72, an abnormality determination means 73, and a switching control means 74. The current change amount calculation means 71 calculates a current change amount ΔI of the reactor current IL over time, and calculates a current change amount ΔI in a predetermined period (for example, an ON period Δt). At this time, the current change amount calculating means 71 may calculate the current change amount ΔI for a predetermined period from the reactor current IL detected at each predetermined detection cycle in the reactor current detecting unit 53, for example. Alternatively, the current change amount calculation means 71 calculates a moving average value for several times of the intake of the reactor current detection unit 53, and calculates a difference between the current detected value of the reactor current IL and the moving average value as the current change amount ΔI. It may be.

  The inductance estimating means 72 estimates the inductance component L of the reactor 21 from the current change amount ΔI of the reactor current IL calculated by the current change amount calculating means 71. Here, the inductance component L of the reactor 21 is expressed by the following formula (1) using the applied voltage VL applied to the reactor 21 and the current change rate (ΔI / Δt) per hour in the reactor 21. be able to.

  In the above formula (1), the applied voltage VL applied to the reactor 21 is a value obtained by rectifying the power supply voltage of the three-phase AC power supply 6 by the three-phase rectifier 10, and can be considered as a constant value if the power supply voltage fluctuation is ignored. it can. On the other hand, the current change rate per hour (ΔI / Δt) can be obtained by the ratio (ΔI / Δt) between the current change amount ΔI and the ON period Δt of the switching element 22 of the transformer circuit 20. In other words, the inductance component L of the reactor 21 can be obtained by the reciprocal of (ΔI / Δt). Thus, the inductance estimation means 72 estimates the inductance component L using the above equation (1).

  When the inductance component L estimated by the inductance estimation unit 72 is equal to or less than the set threshold value Lref and the reactor current IL is larger than the current threshold value ILref (L ≦ Lref, IL> ILref), the abnormality determination unit 73 It is determined that the reactor 21 may be abnormal due to magnetic saturation. That is, the reactor 21 that accumulates energy has a DC superposition characteristic, and the inductance component L of the reactor 21 changes depending on the magnitude of the flowing reactor current IL. In general, when the magnitude of the current increases, the inductance component L tends to decrease. When an excessive current flows through the reactor 21, the inductance component L rapidly decreases due to the magnetic saturation phenomenon of the core. Therefore, the abnormality determination unit 73 determines that an abnormality may occur when the inductance component L becomes equal to or less than the set threshold value Lref.

  Further, the abnormality determination means 73 determines an abnormality using not only the inductance component L but also the reactor current IL. Generally, the magnetic saturation of the reactor 21 occurs when the flowing reactor current IL increases. Therefore, when the current threshold value ILref is also set for the absolute value of the reactor current IL and the reactor current IL is equal to or smaller than the current threshold value ILref (IL ≦ ILref), the inductance component estimated by the inductance estimating means 72 Even if L is smaller than the set threshold value Lref, it is determined that no abnormality occurs.

  The switching control unit 74 controls the ON / OFF operation of the switching element 22 based on the determination result by the abnormality determination unit 73, and includes a voltage command control unit 74a, a current command control unit 74b, and a switching signal generation unit 74c. It has. The voltage command control means 74a calculates a difference between the voltage command value from the command voltage value for the output voltage Vout of the transformer circuit 20 and the output voltage Vout detected by the output voltage detector 51, and performs proportional integral control (PI control). ).

  The current command control unit 74 b calculates a switching command (on duty) of the switching element 22 using the voltage command value calculated by the voltage command control unit 74 a and the reactor current IL detected by the reactor current detection unit 53. Is. For example, the current command control means 74b performs proportional-integral-derivative control (PID control) using the difference between the voltage command value and the reactor current IL as an input and using the on-duty of the switching element 22 as an operation amount.

  The switching signal generation means 74c generates a switching signal SS for driving the switching element 22 based on the on-duty calculated by the current command control means 74b. Specifically, the switching signal generation unit 74c generates a drive pulse (PWM command) in which the on-duty of the switching element 22 is set in synchronization with the carrier frequency based on the switching command calculated by the current command control unit 74b. To do.

  Here, when the switching signal generation unit 74c determines that there is a possibility that the reactor 21 may be abnormal in the abnormality determination unit 73, the reactor current IL is suppressed regardless of the command from the current command control unit 74b or the like. As described above, it has a function of adjusting the ON period Δt of the switching element 22 of the transformer circuit 20.

  Specifically, the switching signal generation unit 74c has a function of storing an on period Δt (on duty) for each control cycle. At this time, the switching signal generation unit 74c may store only the immediately preceding on-duty, or may store the on-duty for each of a plurality of control cycles. When the switching signal generating unit 74c suppresses the reactor current IL, it is not the on-duty set by the current command control unit 74b, but is set in the previous control cycle in which it is determined that no abnormality occurs in the reactor 21. The on-duty switching signal SS is output. As described above, when there is a possibility that the reactor 21 may be abnormal due to magnetic saturation, it is possible to realize an efficient operation of the apparatus without stopping the operation due to an abnormal stop or the like.

  If it is determined that there is an abnormality even when the switching signal SS having the on-duty stored at the previous time is used, the switching control means 74 is driven by the switching signal SS having a preset safe on-duty. Alternatively, driving may be performed with the shortest on-period Δt among a plurality of stored on-duties. Thereby, since the switching element 22 can be reliably driven using the switching signal SS having a short ON period Δt, the possibility of magnetic saturation is reduced, and the continuous operation of the air conditioner 100 can be realized.

  3 is a flowchart showing an operation example of the transformation control means 70 in the power conversion device 1 of FIG. 2, FIG. 4 is a graph showing an example of the reactor current flowing in the reactor 21 of FIG. 1, and FIGS. An example of the operation of the power conversion device 1 will be described with reference to FIG. First, the reactor current IL is detected by the reactor current detection unit 53 during the operation of the power conversion device 1 (step ST1). Then, the current change amount calculating means 71 calculates the current change amount ΔI of the reactor current IL in a predetermined period (on period Δt) (step ST2), and the inductance estimating means 72 calculates the inductance component L based on the above equation (1). It is estimated (step ST3).

  Next, abnormality determination means 73 determines whether or not inductance component L is equal to or smaller than set threshold value Lref and reactor current IL is larger than set current threshold value ILref (step ST4). When inductance component L is equal to or less than set threshold value Lref and reactor current IL is greater than set current threshold value ILref (L ≦ Lref, IL> ILref), it is determined that there is a possibility that abnormality may occur in reactor 21. .

Then, the shortest on-period Δt (on-duty) among the plurality of on-periods (on-duty) stored in the switching control means 74 is read, and the switching signal SS in which the on-period Δt (on-duty) is limited is output. (See FIG. 4, step ST5). On the other hand, when the inductance component L is larger than the set threshold value Lref (L> Lref) or when the reactor current IL is equal to or smaller than the set current threshold value ILref (IL ≦ ILref), the reactor 21 is satisfied. It is determined that there is no possibility that an abnormality will occur (steps ST1 to ST4).

  As described above, the abnormality of the reactor 21 is detected based on the inductance component L and the reactor current IL, and the on-duty of the switching element 22 is limited. Can be improved. In addition, when an abnormality is detected, the operation is not stopped by an abnormal stop or the like, but the transformer circuit 20 can be driven and continued in a range in which magnetic saturation does not occur. It can be carried out.

  That is, when the inductance component L of the reactor 21 is reduced due to magnetic saturation, even if the ON period Δt of the switching element 22 is the same, the current change amount ΔI flowing through the reactor 21 is larger than that in the normal state (see FIG. 4). ). If the inductance component falls more than expected, the overcurrent cutoff circuit operates, the air conditioner 100 stops abnormally, and the switching element 22 constituting the three-phase rectifier 10 and the transformer circuit 20 may be broken or a breaker trip may occur. There is a problem of having sex.

  Therefore, by detecting the occurrence of magnetic saturation according to the calculated inductance component L, it is possible to prevent the occurrence of overcurrent due to the magnetic saturation. Moreover, since it becomes possible to prevent the overcurrent flowing through the three-phase rectifier 10 and the transformer circuit 20 in advance, damage to the switching element 22 of the three-phase rectifier 10 and the transformer circuit 20 can be avoided, and a SiC element having a small short-circuit tolerance, etc. The switching element 22 made of can be applied to the transformer circuit 20. In addition, when an abnormality is detected, the operation is not stopped by an abnormal stop or the like, but the transformer circuit 20 can be driven and continued in a range in which magnetic saturation does not occur. It can be carried out.

  Further, the switching control means 74 outputs the on-duty switching signal SS set in the previous control cycle in which it is determined that no abnormality occurs in the reactor 21 when the on-period Δt is limited. Thus, the operation of the air conditioner 100 can be continued in a state where an abnormality such as magnetic saturation does not occur reliably.

Embodiment 2. FIG.
FIG. 5 is a block diagram showing the configuration of the power conversion device according to the second embodiment of the present invention, and FIG. 6 is a block diagram showing an example of the transformation control means in the power conversion device of FIG. 5, see FIG. 5 and FIG. The power conversion apparatus 101 will be described. In addition, in the power converter device 101 of FIG.5 and FIG.6, the site | part which has the same structure as the power converter device 1 of FIG.1 and FIG.2 is attached | subjected, and the description is abbreviate | omitted. The power converter 101 in FIGS. 5 and 6 is different from the power converter 1 in FIG. 2 in that a reactor temperature detecting unit 54 that detects the reactor temperature TL in order to detect the reactor abnormality (magnetic saturation) more accurately. It is a point which changes electric current threshold ILref with the detected reactor temperature TL.

  Generally, the magnetic saturation of the reactor tends to depend on the reactor temperature TL, and when the reactor temperature TL is high, the current value that leads to magnetic saturation tends to be small. Therefore, abnormality determination means 73 has a threshold value table 73a indicating the relationship between reactor temperature TL and current threshold value ILref, and current is supplied according to reactor temperature TL detected by reactor temperature detecting unit 54. The threshold value ILref is changed. The threshold value table 73a stores such a relationship that the current threshold value ILref decreases as the reactor temperature TL increases.

  FIG. 7 is a flowchart showing an operation example of the transformation control means 70 in the power conversion device 101 of FIGS. 5 and 6. Similarly to the first embodiment, the reactor current detector 53 detects the reactor current IL during the operation of the power converter 1 (step ST11). Then, the current change amount calculating means 71 calculates the current change amount ΔI of the reactor current IL in a predetermined period (ON period Δt) (step ST12), and the inductance estimating means 72 calculates the inductance component L based on the above equation (1). Estimated (step ST13). Thereafter, in abnormality determination means 73, current threshold value ILref is set using reactor temperature TL and threshold value table 73a (step ST14). The current threshold value ILref may be set at any timing of steps ST11 to ST14 as long as it is performed before the abnormality determination. Thereafter, as in the first embodiment of FIG. 4, the reactor current IL is compared with the set current threshold value ILref to determine whether there is an abnormality, and when it is determined that an abnormality has occurred, the on-duty ratio Is limited (steps ST15 and ST16).

  As described above, by changing the threshold current ILref of the reactor current based on the reactor temperature TL, the abnormality of the reactor 21 is accurately detected, and the on-duty of the switching element 22 is limited as in the first embodiment. It becomes possible to suppress the risk of magnetic saturation with higher accuracy.

Embodiment 3. FIG.
FIG. 8 is a block diagram illustrating a configuration of the power conversion device according to the third embodiment of the present invention. The power conversion device will be described with reference to FIG. 8. In FIG. 8, parts having the same configuration as in FIG. The power converter of FIG. 8 is different from the power converter of FIG. 6 in that the inverter circuit 40 of the inverter controller 60 (FIG. 1) is driven when the abnormality determination unit 73 detects the magnetic saturation of the reactor 21 in advance. Inverter frequency suppression means 271 is provided for reducing the inverter frequency (operation frequency) of the drive signal. Thereby, input electric power falls, As a result, the electric current which flows into the reactor 21 can be suppressed, and it becomes possible to reduce the risk of magnetic saturation.

  Specifically, the inverter frequency suppression unit 271 sets a target reactor current target value ILset in advance. For example, the inverter frequency suppression means 271 stores in advance an inductance characteristic with respect to the reactor current IL as shown in FIG. 9, and a current value corresponding to the minimum inductance component L to be secured using the reactor current-inductance characteristic is set as the reactor current target. Determined as value ILset. As described above, since the inductance component L varies depending on the reactor temperature TL, the inverter frequency suppression unit 271 adjusts the reactor current target value ILset based on the reactor temperature TL detected by the reactor temperature detection unit 54. For example, the reactor current target value ILset is decreased when the temperature is high, and is increased when the temperature is low. In addition, although inverter frequency suppression means 271 has illustrated about the case where reactor current target value ILset is set using an inductance characteristic like FIG. 9, it is set to the same value as current threshold value ILref demonstrated in Embodiment 1 and 2. It may be set.

  Then, when the reactor current IL is higher than the reactor current target value ILset, the inverter frequency suppression means 271 in FIG. 8 suppresses the inverter frequency (operation frequency) so that the reactor current IL becomes equal to or lower than the reactor current target value ILset. The inverter control means 60 is operated. For example, in the case of a load such as the compressor 2, when the inverter frequency (operation frequency) is lowered, the input power is lowered, and as a result, the reactor current IL is reduced. As described above, the inverter frequency suppression unit 271 controls the inverter frequency (operation frequency) so that the reactor current IL detected by the reactor current detection unit 53 becomes the reactor current target value ILset, which has been described in the first embodiment. Along with the suppression of on-duty, the absolute value of the reactor current IL can be reduced, and the magnetic saturation risk of the reactor can be reduced while the operation is continued. In addition, although illustrated about the case where the reactor temperature detection part 54 is provided in the power converter device of FIG. 8, the reactor temperature detection part 54 does not need to be provided like FIG.1 and FIG.2.

Embodiment 4 FIG.
FIG. 10 is a block diagram illustrating configurations of an air-conditioning apparatus and a power conversion apparatus according to Embodiment 4 of the present invention. The air-conditioning apparatus and the power conversion apparatus will be described with reference to FIG. In FIG. 10, parts having the same configuration as those of the air conditioner of FIGS. 5 and 6 are denoted by the same reference numerals, and description thereof is omitted. The air conditioner of FIG. 10 is different from the air conditioner of FIGS. 5 and 6 in that, when the magnetic saturation of the reactor 21 is detected by the abnormality determining means 73, the reactor current IL is reduced in order to reduce the reactor current IL. This is a point that has high pressure suppressing means 371 that adjusts the driving ability (high pressure) to suppress input power.

  In general, it is known that when the high pressure of the compressor 2 is reduced, the load torque of the compressor 2 is reduced, so that the current flowing through the compressor 2 is reduced. Therefore, when the high pressure is lowered, the input power can be suppressed, the current flowing through the reactor 21 is also reduced, and as a result, the risk of reaching magnetic saturation can be reduced. In addition, in FIG. 10, the inverter frequency suppression means 271 shown in Embodiment 3 of FIG. 8 may be further provided, and the reactor temperature detection part 54 does not need to be provided like FIG.1 and FIG.2. .

Embodiment 5. FIG.
FIG. 11 is a block diagram illustrating configurations of an air-conditioning apparatus and a power conversion apparatus according to Embodiment 5 of the present invention. The air-conditioning apparatus and the power conversion apparatus will be described with reference to FIG. In the air conditioner of FIG. 11, parts having the same configurations as those of the air conditioner of FIGS. 5 and 6 are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 11, the air conditioner according to the fifth embodiment blows air to a heat exchanger on the outdoor unit side serving as a condenser or an evaporator in addition to the configuration of the second embodiment (FIGS. 5 and 6). At the same time, the blower 3a that blows air to the reactor 21 and the fan control means 471 that adjusts the rotational speed of the blower 3a so as to cool the reactor 21 when it is determined by the abnormality determination means 73 that the reactor 21 may be abnormal. And have.

  As described above, the magnetic saturation of the reactor 21 affects the reactor temperature TL. If the reactor temperature TL is high, the current value that leads to magnetic saturation decreases. For this reason, when magnetic saturation is detected in advance by the abnormality determination means 73, for example, when the reactor 21 is installed in the outdoor unit, the air volume increases by cooling the reactor 21 by increasing the rotational speed of the blower 3a. Let Then, the temperature rise of the reactor 21 is suppressed, and the risk of magnetic saturation can be suppressed in a state where the operation is continued without causing an abnormal stop. 11 may further include the inverter frequency suppression unit 271 shown in the third embodiment of FIG. 8 or may further include the high-pressure suppression unit 371 shown in the fourth embodiment of FIG. Or the reactor temperature detection part 54 does not need to be provided like FIG.1 and FIG.2.

  The embodiment of the present invention is not limited to the above embodiment. For example, when the switching signal generation unit 74c of FIG. 2 limits the on period of the switching signal SS, the case where the on period Δt (on duty) at the previous setting is used is illustrated, but an abnormality due to magnetic saturation does not occur. Any method may be used as long as the on-period Δt is limited, for example, an on-period Δt that does not cause magnetic saturation may be stored in advance, or a predetermined ratio (for example, 80%) of the on-period Δt. You may make it set to.

  Moreover, although the case where the current threshold value ILref is changed based on the reactor temperature TL is illustrated, the reactor temperature TL may be directly determined instead of the determination based on the reactor current IL. Specifically, a set temperature threshold that may cause magnetic saturation is provided, and magnetic saturation occurs when the reactor temperature TL is equal to or higher than a preset set temperature threshold. You may make it judge. Even in this case, since the abnormality is detected using not only the reactor temperature TL but also the inductance component L, the accuracy of the abnormality detection can be improved and an efficient operation can be realized.

  In the above embodiment, the case where the transformer circuit 20 of FIG. 1 is a booster circuit is illustrated. However, a step-down circuit or a step-up / step-down circuit capable of boosting and stepping down may be used. Furthermore, in the said embodiment, although illustrated about the case where the power converter device 1 is used for the air conditioning apparatus 100, not only this but the motor mounted in a motor vehicle etc. may be driven.

  DESCRIPTION OF SYMBOLS 1,101 Power converter device, 2 Compressor, 3 Condenser, 3a Blower, 4 Throttling device, 5 Evaporator, 6 Three-phase AC power supply, 10 Three-phase rectifier, 20 Transformer circuit, 21 Reactor, 22 Switching element, 23 Backflow Prevention element, 30 smoothing capacitor, 40 inverter circuit, 51 output voltage detector, 52 motor current detector, 53 reactor current detector, 54 reactor temperature detector, 60 inverter control means, 70 transformer control means, 71 calculation of current change Means, 72 inductance estimation means, 73 abnormality determination means, 73a threshold value table, 74 switching control means, 74a voltage command control means, 74b current command control means, 74c switching signal generation means, 100 air conditioner, 271 inverter frequency suppression 371 High pressure suppression hand 471 Fan control means, IL reactor current, ILref current threshold, ILset current target value, L inductance component, Lref setting threshold, M load, SS switching signal, TL reactor temperature, Vout output voltage, VL reactor Applied voltage, ΔI Current change amount, Δt ON period (ON duty).

Claims (10)

A rectifier that rectifies the AC voltage supplied from the AC power supply;
A transformer circuit having a reactor, a switching element, and a backflow prevention element, and transforming an output voltage from the rectifier;
A smoothing capacitor for smoothing the output from the transformer circuit;
An inverter circuit for converting a DC voltage smoothed by the smoothing capacitor into an AC voltage;
A reactor current detection unit for detecting a reactor current flowing through the reactor of the transformer circuit;
Based on the reactor current detected by the reactor current detection unit, the on-period of a switching signal for driving the switching element of the transformer circuit is controlled, and a transformer control means for controlling the operation of the transformer circuit. Prepared,
The transformation control means includes
Inductance estimating means for estimating an inductance component of the reactor from a current change amount in a predetermined period of the reactor current;
Abnormality determining means for determining that there is a possibility of abnormality in the reactor when the inductance component estimated by the inductance estimating means is less than or equal to a threshold value and the reactor current is larger than a preset current threshold value. When,
Switching signal control means for adjusting an ON period of a switching signal so that the reactor current is suppressed when it is determined in the abnormality determination means that the reactor may be abnormal. Conversion device. The switching signal control unit has a function of storing an ON period of the switching signal for each control cycle, and when the abnormality determination unit determines that there is a possibility that the reactor may be abnormal , The power converter according to claim 1, wherein the reactor current is suppressed by outputting a switching signal having the shortest on period among the on periods.   The power converter according to claim 1, further comprising a reactor temperature detection unit that detects a temperature of the reactor as a reactor temperature.   The abnormality determination means has a threshold table in which the current threshold value is set for each reactor temperature, and the reactor temperature detected by the reactor temperature detector and the threshold table are The power conversion device according to claim 3, wherein the current threshold value is used to set the current threshold value.   5. The inverter frequency suppressing means for suppressing the drive frequency of the inverter circuit when the abnormality determining means determines that there is a possibility that an abnormality may occur in the reactor. The power converter device of Claim 1.   The power conversion device according to claim 1, wherein the switching element and / or the backflow prevention element is formed of a wide band gap semiconductor.   The power converter according to claim 6, wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material, or diamond. An air conditioner having a compressor, a condenser, a throttle means, and an evaporator, and having a refrigerant circuit for circulating the refrigerant,
The air conditioner characterized by the said compressor having a motor rotated by the power converter device of any one of Claims 1-7.   9. The air conditioner according to claim 8, further comprising a high-pressure suppressing unit that suppresses an operation capability of the compressor when it is determined by the abnormality determining unit that an abnormality may occur in the reactor. apparatus. A blower that blows air to the condenser or the heat exchanger that becomes the evaporator and blows to the reactor,
Fan control means for adjusting the rotational speed of the blower so that the reactor is cooled when it is determined by the abnormality determination means that there is a possibility of abnormality in the reactor. The air conditioning apparatus according to claim 8 or 9.

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