JP2011112334A - Air conditioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein, since the optimum operation region of a boosting chopper circuit seen from a viewpoint of harmonic suppression differs from that seen from a viewpoint of a motor characteristic or the like, harmonic suppression and improvement of the circuit loss cannot be effectively performed. <P>SOLUTION: In the air conditioning system constituted by a plurality of air conditioners 101 connected to a three-phase AC power supply 1, the each air conditioner is equipped with: a rectifying circuit for rectifying the three-phase AC power supply; a boosting converter part for boosting an output voltage of the rectifying circuit; an inverter part receiving the output of the boosting converter part and driving a motor; a load state detecting means for detecting a load state of the air conditioner; and an operation mode determination part 16 setting a plurality of operation modes and controlling operation of the boosting converter part, based on the operation mode and the load state. In each operation mode determination part, the operation mode is set so that the circuit loss of the whole of the air conditioning system is the minimum on the condition that the harmonic amount generated from the air conditioning system is equal to or less than the prescribed value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an air conditioning system including a plurality of air conditioners including a boost converter.

  Generally, a three-phase AC power source is used in a commercial air conditioner that is larger than a home-use air conditioner. In a device compatible with a three-phase AC power supply, the output voltage of the three-phase rectifier circuit is filtered by a three-phase rectifier circuit that rectifies the three-phase AC voltage as a three-phase full-wave rectifier converter, and a reactor and a capacitor. A filter circuit and an inverter circuit that converts an output voltage of the filter circuit into an AC voltage and drives a motor are used.

  For such a three-phase full-wave rectifier converter, for the purpose of providing a power converter that can increase the power factor of the power source using a single three-phase rectifier circuit and a single boost chopper circuit, A power converter configured to include a reactor for accumulating an output charge of a rectifier circuit and a switching element for controlling charging / discharging of the charge accumulated in the reactor according to a pulse width of a pulse signal. Known (for example, Patent Document 1).

  In addition, in order to provide a control device that smoothes the start / stop characteristics of the motor for the centrifuge motor control device, the operation of the boost converter is stopped in the low-speed rotation region when the motor is started / stopped. Then, the voltage applied to the motor is suppressed by adjusting the charging voltage of the smoothing capacitor by the pulse width modulation and the AC phase control element, and when the motor is in the high speed rotation region, the AC phase control element is made conductive. At the same time, a booster converter is operated to suppress the voltage applied to the motor by pulse width modulation (for example, Patent Document 2).

  In addition, for the purpose of providing a control device for an air conditioner that can prevent rotation stop due to motor torque shortage and burnout of winding due to overexcitation, And a means for controlling the inverter means using different V / f patterns (for example, Patent Document 3).

  Further, the input AC current waveform can be made substantially sinusoidal even in a low input AC current region, and the input AC current can be provided with a control device for the air conditioner that can reduce the harmonic current. It is known that the resistance value of the resistance means is larger when the input AC current is smaller than when the input AC current is large (for example, Patent Document 4).

Japanese Patent No. 2869498 JP-A-7-256147 JP-A-10-52092 JP-A-10-52050

  The power supply current in the conventional three-phase full-wave rectification type converter is in a pulse shape, and at this time, a harmonic component of the power supply current appears greatly. Therefore, it is necessary to suppress the harmonic current by the DC reactor. At this time, since the inductance value of the DC reactor is increased, there is a problem that the DC reactor is increased in size, increased in loss, and increased in cost.

  In particular, according to NISA NISA's “Guidelines for Harmonic Suppression for Consumers Receiving Power at High Voltage or Extra High Voltage” established in January 2004 (hereinafter abbreviated as “Specific Consumer Guidelines”), There is a limit on the amount of harmonics (harmonic outflow current) of each order per customer's contract power, and it is required to take measures to suppress harmonics so as not to exceed it. In particular, suppression of the fifth harmonic current is demanded.

  In addition, when introducing an air conditioning system to a consumer, if the harmonic current of the consumer to be introduced exceeds the limit determined by the specific consumer guideline, for example, a countermeasure for suppressing harmonics such as an active filter can be retrofitted. There is a need.

  While such harmonic suppression measures are required, when a boost chopper circuit is operated in the entire operation range as in Patent Document 1, a harmonic drive can be suppressed, but a motor driven as a load Depending on the operating range, there is a problem that the start / stop characteristics of the motor deteriorates, the motor torque is insufficient or overexcited, or the accuracy of current detection deteriorates, resulting in an increase in circuit loss.

  Furthermore, like the techniques shown in Patent Documents 2 to 4 made to solve the problem of Patent Document 1, the operation / stop of the boost chopper circuit is switched in the low speed region / high speed region of the motor operating range, A technique for optimizing the bus voltage has been proposed, but there is a problem that harmonic current cannot be reduced when the boost chopper circuit is stopped in a low speed region.

  Therefore, while it is desirable to operate the boost chopper circuit from a low speed range from the viewpoint of suppressing harmonics, it is desirable to operate the boost chopper circuit only from the high speed range from the viewpoint of motor characteristics and the like. Since the optimum operating region of the step-up chopper circuit differs between the viewpoint of wave suppression and the viewpoint of circuit loss suppression, there is a problem that harmonic suppression measures and circuit loss improvement cannot be effectively performed.

  An air conditioning system according to the present invention is made to solve the above-described problems, and is an air conditioning system including a plurality of air conditioners connected to a three-phase AC power source. The air conditioner includes a rectifier circuit that rectifies a three-phase AC power source, a boost converter unit that boosts the output voltage of the rectifier circuit, an inverter unit that receives the output of the boost converter unit, and drives a motor, and an air conditioner A load condition detection means for detecting a load condition, and an operation mode determination unit that can set a plurality of operation modes and controls the operation of the boost converter unit based on the operation mode and the load condition; In each operation mode determination unit, the operation mode is determined so that the circuit loss of the entire air conditioning system is minimized under the condition that the amount of harmonics generated from the air conditioning system is a predetermined value or less. One in which but is set.

  According to the present invention, in an air conditioning system including a plurality of air conditioners including a boost converter, air conditioning that can effectively perform harmonic suppression measures and circuit loss improvement of the entire air conditioning system. You can get a system.

1 is a configuration diagram of an air conditioning system according to Embodiment 1. FIG. 1 is a circuit configuration diagram of an air conditioner according to Embodiment 1. FIG. It is a block diagram of the switching control means of the air conditioner according to Embodiment 1. It is a block diagram of the operation mode determination part of the air conditioner concerning Embodiment 1. FIG. It is a power supply current waveform diagram for one cycle of the boost converter unit, (A) when the boost converter unit is stopped, (B) is a diagram during operation of the boost converter unit. It is a block diagram of the air conditioning system which concerns on Embodiment 2. FIG. It is a circuit block diagram of the air conditioner which concerns on Embodiment 2. FIG. 6 is a flowchart of an operation monitoring control unit of an air conditioning system according to Embodiment 2. FIG. FIG. 6 is a configuration diagram of an air conditioning system according to Embodiment 3. It is a block diagram of the air conditioning system which concerns on Embodiment 4.

Embodiment 1 FIG.
1 is a configuration diagram of an air-conditioning system according to Embodiment 1. FIG. In FIG. 1, the air conditioner system includes a plurality of air conditioners 101, and each of the air conditioners 101 is provided with an operation mode determination unit 16. In the operation mode determination unit 16, for example, an operator who installs the air conditioning system in a building or the like makes a setting to determine the operation mode described later. These air conditioners 101 are connected to a three-phase AC power source 1, and a three-phase AC voltage is supplied by the three-phase AC power source 1.

  FIG. 2 is a circuit configuration diagram of the air conditioner 101 according to the first embodiment. In FIG. 2, a three-phase AC power source 1 is connected to a three-phase rectifier 2. The three-phase rectifier 2 has a configuration in which six rectifier diodes 2a to 2f are bridge-connected. The output side of the three-phase rectifier 2 is connected to the boost converter unit 3. A bus current detection unit 8 is provided on the bus between the three-phase rectifier 2 and the boost converter unit 3.

  The boost converter unit 3 includes a boost reactor 4, a switching element 5 such as an IGBT (Insulated Gate Bipolar Transistor), and a backflow prevention element 6 such as a fast recovery diode. The output side of the boost converter unit 3 is connected to the smoothing capacitor 7. In addition, an output voltage detector 9 is provided in parallel with the smoothing capacitor 7.

  The switching element 5 is controlled by the switching control means 10. The switching control means 10 performs switching based on a detection value in the bus current detection unit 8, a detection value in the output voltage detection unit 9, and a converter operation / stop signal output from an operation mode determination unit 16 described later. A drive signal for operating the element 5 is generated.

  An inverter circuit 12 is connected to the output side of the smoothing capacitor 7. The inverter circuit 12 includes switching elements 12a to 12f such as IGBTs. The output side of the inverter circuit 12 is connected to the motor 15. The current flowing through the motor 15 is detected by the motor current detection means 13.

  The inverter circuit 12 is driven by the inverter driving means 14. The inverter drive unit 14 generates a drive signal for operating the inverter circuit 12 based on the detection value of the motor current detection unit 13 and the detection value of the output voltage detection unit 9, and drives the inverter circuit 12. Moreover, the inverter drive means 14 outputs a load condition signal to the operation mode determination part mentioned later.

  FIG. 3 is a configuration diagram of the switching control means 10 of the air conditioner according to the first embodiment. In FIG. 3, the bus current command value calculation unit 21 calculates a bus current command value from the bus voltage detection value detected by the output voltage detection unit 9 and a bus voltage command value that is arbitrarily specified separately, and outputs it. .

  The on-duty calculation unit 22 calculates the on-duty of the switching element 5 from the bus-current command value and the bus-current detection value at the bus-current detection unit 8. The drive pulse generator 23 generates a drive pulse for operating the switching element 5 based on the on-duty calculated by the on-duty calculator 22 and a converter operation / stop signal described later.

  FIG. 4 is a configuration diagram of the operation mode determination unit 16 of the air conditioner according to the first embodiment. In FIG. 4, in the operation mode setting part 31, the operation mode of an air conditioner is set so that it may fit the calculation document etc. in a specific consumer guideline as mentioned above, for example. The operation mode will be described in the operation described later. The converter operation / stop determination unit 32 is a load for grasping the load status command from the operation mode setting unit 31 and the load status of the air conditioner 101 alone, such as the operation frequency output from the inverter driving means 14. Based on the status signal, the operation or stop of the converter is determined and a converter operation / stop signal is output.

  In addition, although the operating frequency output from the inverter drive means 14 was mentioned above as a load condition signal of the air conditioner 101 alone, it is not limited to this, for example, the bus current value detected by the bus current detecting unit 8 The same effect can be obtained by using a signal such as a motor current value detected by the motor current detecting means 13.

Next, the operation will be described.
In FIG. 2, the AC voltage of the three-phase AC power source 1 is rectified by a three-phase rectifier 2 to become a DC voltage. The switching control means 10 controls on / off of the switching element 5 of the boost converter unit 3, and the bus voltage from the three-phase rectifier 2 is boosted by the chopping.

  Here, in the boost converter unit 3, when the switching element 5 is turned on, the backflow prevention element 6 is prevented from conducting, and the voltage rectified by the three-phase rectifier 2 is applied to the boost reactor 4. On the other hand, when the switching element 5 is turned off, the backflow prevention element 6 is conducted, and a voltage in the reverse direction to that when the switching element 5 is on is induced in the boost reactor 4. At this time, from the viewpoint of energy, it can be seen that the energy accumulated in the boost reactor 4 when the switching element 5 is turned on is transferred to the inverter circuit 12 which is a load when the switching element 5 is turned off. Therefore, the bus voltage can be controlled by controlling the on-duty of the switching element 5.

  The on-duty control is performed by the on-duty calculation unit 22 in the switching control unit 10, and the processing in the switching control unit 10 is performed as follows, for example.

  In FIG. 3, the bus current command value calculation unit 21 determines the bus current command value so that the deviation between the bus voltage command value and the detection value of the output voltage detection unit 9 is zero. The on-duty calculation unit 22 determines the on-duty so that the deviation between the bus current command value calculated by the bus current command value calculation unit 21 and the detection value of the bus current detection unit 8 is zero. Based on this on-duty value and a converter operation / stop signal described later, the drive pulse generator 23 generates a drive pulse for operating the switching element 5. Based on this drive pulse, the bus voltage is controlled by controlling the opening and closing of the switching element 5.

  The operation mode determination unit 16 that outputs the converter operation / stop signal will be described. In FIG. 4, the operation mode setting unit 31 in the operation mode determination unit 16 sets the operation mode for each air conditioner 101 in advance. As the operation mode, for example, either one of the harmonic reduction priority mode and the loss reduction priority mode can be set.

  The harmonic reduction priority mode is a mode in which the boost converter unit 3 is operated from a range where the air conditioner 101 has a low load, and although the loss increases, the harmonic reduction can be effectively achieved in the entire range. . The loss reduction priority mode is a mode in which the boost converter unit 3 is operated only in a range where the air conditioner 101 has a high load. Although harmonics cannot be reduced, the loss can be effectively reduced over the entire range. This is a possible mode.

  The operation mode setting unit 31 outputs a preset load status command based on any of the above modes. The load status command is a threshold value used as a reference when the converter operation / stop determination unit 32 compares the load status signal with the load status signal. In the harmonic reduction priority mode, the air conditioner 101 increases the pressure from the low load range. In order to operate the converter unit 3, this threshold value is set low. On the other hand, in the loss reduction priority mode, the air conditioner 101 operates the boost converter unit 3 only in a high load range. Higher than the threshold value.

  In the above description, the operation mode of the air conditioner 101 has been described using the harmonic reduction priority mode and the loss reduction priority mode. However, as the effects of harmonic reduction and loss reduction, the harmonic reduction priority mode and At least one operation mode in which the operation range of the boost converter unit 3 is changed may be added so as to obtain an intermediate effect of the loss reduction priority mode. Further, a numerical value of the direct load status command, that is, a threshold value serving as a reference for comparison with the load status signal may be set.

  Then, converter operation / stop determination unit 32 compares the load status command with the load status signal and outputs a converter operation / stop signal. For example, when the load status signal is the motor operating frequency, if the motor operating frequency is higher than the load status command, a converter operation / stop signal is output to operate the converter, otherwise A converter operation / stop signal is output to stop the converter.

  Here, when the boost converter unit 3 is operated, the voltage applied to the inverter circuit 12 is increased, that is, the output voltage of the inverter circuit 12 can be increased. Accordingly, the line voltage of the motor 15 can be increased, so that the phase current of the motor 15 is reduced. In the inverter circuit 12, the current flowing through the switching elements 12a to 12f constituting the inverter circuit 12 is reduced.

  For this reason, although the loss increases by the loss in the boost converter unit 3 as compared with the case where the boost converter unit 3 does not perform boosting, the inverter loss is reduced by boosting, so the loss of the entire circuit is reduced.

  Further, when the motor 15 is driven, a voltage is applied to the motor 15 by the inverter circuit 12, and the upper limit of the applied voltage is determined by the bus voltage, while the applied voltage necessary for driving the motor 15 is proportional to the operating frequency. Therefore, the upper limit of the operating range of the motor 15 is determined by the bus voltage. Further, when the number of turns of the motor winding is increased, the induced voltage φ increases in proportion to the number of turns N as shown in [Formula 1], and therefore the upper limit of the number of turns N of the motor winding is also determined by the bus voltage.

  When boosting the bus voltage with the boost converter unit 3, the upper limit can be increased. For example, the operation range of the motor 15 can be increased to improve the performance as an air conditioner, and a desired operation range can be secured. The number of turns N of the motor winding can be increased within the range to be applied.

  In general, when the number of turns N of the motor winding is increased, the winding resistance R is proportional to the square of the number of turns N as shown in [Equation 2], and the motor current I as shown in [Equation 3]. There is a relationship inversely proportional to the number of turns N. At this time, the motor copper loss Loss_motorcp due to the winding resistance does not depend on the number of turns N as shown in [Formula 4].

  As described above, if the line voltage of the motor 15 can be increased to reduce the phase current of the motor 15, the conduction loss in the inverter circuit 12 can be reduced. Therefore, by increasing the number of turns N of the motor winding, The conduction loss in the inverter circuit 12 can be reduced without increasing the loss.

  Therefore, if the bus voltage is boosted by the boost converter unit 3, the number N of windings of the motor 15 can be increased. That is, by designing the number of windings of the motor 15 in accordance with the maximum output voltage of the boost converter unit 3, that is, the input voltage of the inverter circuit 12, it is possible to further reduce the conduction loss in the inverter circuit 12.

  The loss reduction effect by boosting as described above can be obtained only in a range where the voltage applied to the motor 15 is limited when boosting by the boosting converter unit 3 is not performed. Therefore, in the low load range below this, if the switching element 5 is turned off by the switching control means 10 and the operation of the boost converter unit 3 is stopped, the loss in the boost converter unit 3 can be suppressed. Note that the effect of increasing the number of turns of the motor winding can be obtained even when the boost converter unit 3 is stopped outside the range where the voltage applied to the motor 15 is limited.

  Next, operation waveforms will be described with reference to FIG. FIG. 5 is a power supply current waveform diagram for one cycle of the boost converter unit 3. FIG. 5A is a diagram when the boost converter unit 3 is stopped, and FIG. In FIG. 5, time is plotted on the horizontal axis and current value is plotted on the vertical axis.

  After the AC voltage of the three-phase AC power source 1 is rectified by the three-phase rectifier 2, each phase of the power source becomes conductive near 120 deg where the phase voltage is maximum or minimum, and the same current as the bus current flows when conducting.

  When boosting by the boosting converter unit 3 is not performed, the power supply current waveform is as shown in FIG. Since the current ripple depends on the inductance value of the boost reactor 4, the smaller the load, the larger the ratio of the current ripple to the effective current, and the smaller the load.

  On the other hand, when boosting by the boost converter unit 3 is performed, the power source current waveform is as shown in FIG. 5B because the on / off of the switching element 5 is controlled so that the power source current has a 120 deg rectangular wave shape. The rise of current when the switching element 5 is on and the fall of current when it is off vary linearly as shown in the figure. The rate of change of this current is determined as shown in [Equation 5] by the voltage applied to the boost reactor 4 and the inductance value L.

In addition, the meaning of each symbol in [Formula 5] is as follows.
Ilon: current that flows in the boost reactor 4 when the switching element 5 is on Vlon: voltage that is applied to the boost reactor 4 when the switching element 5 is on Iloff: current that flows through the boost reactor 4 when the switching element 5 is off Vloff: Voltage applied to boost reactor 4 when off

  Since the current ripple rate at the time of boosting by the boosting converter unit 3 is determined by the on time or the off time, the current ripple rate can be reduced by increasing the switching frequency. In addition, the inductance value can be reduced.

  The harmonic component of the power supply current is reduced by reducing the current ripple in the 120 deg energization section and keeping the current constant. When boosting by the boosting converter unit 3 is not performed, it is necessary to increase the inductance value of the reactor, which increases the size and loss. On the other hand, at the time of boosting by the boosting converter unit 3, the current ripple in the 120 deg energization section can be reduced by controlling the switching element 5, so that the harmonic component of the power supply current is reduced without increasing the inductance value. be able to. During boosting by the boost converter unit 3, the on-duty of the switching element 5 is controlled to control the power supply current in a rectangular wave shape.

  As described above, for each air conditioner 101, it is desirable to stop the boost converter unit 3 in order to reduce the loss in the low load range. However, if the inductance value is small, the boost converter unit 3 is stopped. The harmonic component is sometimes large, and the harmonic component cannot be reduced as compared with the conventional circuit configuration without the boost converter unit 3. For this reason, the operation mode setting unit 31 sets the operation mode in order to reduce harmonic components in the entire air conditioner system.

  For example, if the amount of harmonics in the entire air conditioning system exceeds the limit on the calculation document in the specific consumer guidelines, many air conditioners 101 set in the harmonic reduction priority mode are installed, and the specific consumer guidelines An air conditioning system is configured to clear the restrictions. Thereby, since the effect of harmonic reduction can be added to the air conditioner 101, it is possible to reduce the number of installed harmonic suppression countermeasure devices. Further, by setting the other air conditioner to the loss reduction priority mode, it is possible to suppress an increase in loss in the harmonic reduction priority mode.

  For example, when priority is given to improving the efficiency of the entire air conditioning system, the air conditioning system is configured only by the air conditioner 101 set to the loss reduction priority mode, and the harmonics are limited to the restrictions in the specific consumer guidelines. It is good also as responding with a wave suppression countermeasure apparatus.

  If an intermediate operation mode is provided in addition to the harmonic reduction priority mode and loss reduction priority mode, or a threshold value used as a reference for comparison with the load status signal can be arbitrarily set, for example, a building or the like If the amount of harmonics in the facility has a margin for the restriction of harmonic regulation but the limit is exceeded when one device is set to the loss reduction priority mode, an intermediate operation mode or an arbitrary threshold is used. As a result, it is possible to obtain the maximum loss reduction effect within the restrictions imposed by the harmonic regulation.

  According to the first embodiment, in an air conditioning system including a plurality of air conditioners including a boost converter, by setting a harmonic reduction priority mode and a loss reduction priority mode for each air conditioner 101 There is an effect that it is possible to obtain an air conditioning system that effectively performs harmonic suppression measures and circuit loss improvement of the entire air conditioning system.

  In addition, by increasing the number of operation modes or making it possible to directly set the numerical value of the load status command, the settings of the individual air conditioners 101 can be finely adjusted, resulting in a loss of the entire air conditioning system. There is an effect that the reduction effect can be obtained to the maximum.

Embodiment 2. FIG.
In the first embodiment, when the air conditioning system is introduced, for example, the amount of harmonics in the entire air conditioning system is calculated on a calculation document in a specific consumer guideline, and when the limit is exceeded, the operation mode of each air conditioner 101 is set. It will be set and harmonic suppression measures will be taken.

  However, the amount of harmonics calculated on such a calculation sheet calculates the maximum value in the operating range of the air conditioner. Moreover, in an actual operation situation, not only a situation where all the air conditioners are operating in the air conditioning system, but also a situation where there is a stopped air conditioner depending on the season and time zone. Therefore, the amount of harmonics in the actual driving situation may be smaller than the amount of harmonics in the calculation document.

  Therefore, in the second embodiment, the operation mode is set based on the actual operation stop state of each air conditioner 101.

  FIG. 6 is a configuration diagram of an air-conditioning system according to Embodiment 2. 6, the same components as those in FIG. 1 are denoted by the same reference numerals, and differences from FIG. 1 will be described. In addition to the operation mode determination unit 16, the air conditioner 101 is provided with an operation stop state detection unit 17. The operation stop status detection means 17 detects the operation stop status of the air conditioner 101. The operation stop state detection means 17 detects, as the operation stop state, for example, information such as the model of the operating air conditioner and the amount of harmonics generated in the calculation document of the operating air conditioner. In the former case, the operation monitoring control unit 102 may set the relationship between the model and the amount of harmonics in advance.

  Further, the operation monitoring control unit 102 is connected to the plurality of air conditioners 101, and monitors the individual operation stop status of the air conditioner 101 detected by the operation stop status detection means 17, and each air conditioner. The operation mode is set for the operation mode determination unit 16 of the machine 101. Therefore, in the configuration diagram of the operation mode determination unit 16 shown in FIG. 4, the setting for the operation mode setting unit 31 is performed by the operation monitoring control unit 102 based on the actual operation stop state in the present embodiment. .

  FIG. 7 is a circuit configuration diagram of an air conditioner according to Embodiment 2. In FIG. 7, the same components as those in FIG. 2 are denoted by the same reference numerals, and differences from FIG. 2 will be described. The operation stop state detection means 17 detects the operation stop state of the air conditioner 101 and transmits it to the operation monitoring control unit 102. In addition, the operation mode determination unit 16 sets the operation mode based on the control signal from the operation monitoring control unit 102.

  In addition, when other devices other than the air conditioner 101 are connected to the same three-phase AC power source 1, operation stop state detection means is also provided in the other devices and transmitted to the operation monitoring control unit 102. It is good also as composition to do.

  Next, the operation will be described. FIG. 8 is a flowchart of the operation monitoring control unit 102 of the air-conditioning system according to Embodiment 2.

  In FIG. 8, STEP 1 is a step in which the operation stop status of the air conditioner 101 is detected by the operation stop status detection means 17. STEP 2 is a step of calculating the total amount of harmonics of the operating air conditioner based on the operation stop condition detected in STEP 1. STEP 3 is a step of calculating the difference between the total amount of harmonics and the limit value in the harmonic regulation.

  In addition, when other apparatuses other than the air conditioner 101 are connected to the same three-phase AC power source 1, the operation stop status from the other apparatuses may be detected in STEP1 to STEP2.

  STEP4 is a step of determining whether or not the harmonic regulation is cleared based on the difference calculated in SETP3. If it is judged that the harmonic regulation is cleared, the number of harmonic reduction priority modes is the smallest and the loss reduction priority is given in STEP5 to maximize the amount of harmonics within the range where the harmonic regulation is cleared. In order to maximize the number of modes, the operation mode of the air conditioner 101 is determined.

  If it is determined in STEP 4 that the harmonic regulation is not cleared, the operation mode of the air conditioner 101 that clears the harmonic regulation is determined in STEP 6. In STEP 6, the loss of the air conditioning system can be minimized by determining the operation mode so that the number of harmonic reduction priority modes is the smallest and the number of loss reduction priority modes is the largest. it can.

  STEP 7 is a step of outputting the operation mode of the air conditioner 101 determined in STEP 5 or STEP 6 to the operation mode determination unit 16 as an operation mode command.

  According to the second embodiment, since the operation stop state of the air conditioner in the air conditioning system is detected and the operation mode is determined based on the detected operation stop state, loss reduction is performed based on the actual operation stop state. There is an effect that can be.

In addition, the number of devices in loss reduction priority mode can be maximized on condition that the amount of harmonics of the air conditioner that is in operation is less than or equal to the limit specified by the specific consumer guidelines, for example. There is an effect that loss can be reduced more effectively.

  In addition, other devices connected to the same three-phase AC power source 1 are also provided with an operation stop status detection means, and the operation monitoring control unit 102 considers the operation stop status of the other devices and takes into account the harmonics of the entire system. If it is set as the structure which calculates wave quantity, there exists an effect that a harmonic measure can be taken also including another apparatus.

Embodiment 3 FIG.
In the second embodiment, the operation stop state of each device is detected and the operation mode of each air conditioner 101 is set. However, the actual harmonic amount may not always match. Therefore, in this embodiment, the harmonic amount detection unit 103 is installed in each device.

  FIG. 9 is a configuration diagram of an air-conditioning system according to Embodiment 3. After the power line from the three-phase AC power supply 1 branches to each air conditioner 101, the harmonic amount detection unit 103 is connected to each air conditioner 101. The harmonic amount detection unit 103 actually detects the harmonic amount of the operating air conditioner, and the operation monitoring control unit 102 determines the operation mode of the converter of the air conditioner 101 as in the second embodiment. To do.

  In addition, when a device other than the air conditioner 101 is connected to the three-phase AC power source 1, the harmonic amount detection unit 103 may be connected to the other device.

  According to the present embodiment, the actual harmonic amount of each air conditioner 101 can be detected to determine the operation mode of the converter, so that the effect of the loss reduction priority mode can be obtained more effectively. .

  In addition, harmonics are detected for all devices connected to the three-phase AC power source 1 by connecting the harmonic amount detection unit 103 to other devices other than the air conditioner 101 and detecting the amount of harmonics. There is an effect that measures can be taken.

Embodiment 4 FIG.
FIG. 10 is a configuration diagram of an air-conditioning system according to Embodiment 4. The harmonic amount detection unit 103 is provided before the power line from the three-phase AC power source 1 branches to each air conditioner 101. The harmonic amount detection unit 103 detects the harmonic amount in the entire power supply system including the other devices 104, and the operation monitoring control unit 102 determines the individual operation mode of the air conditioner constituting the air conditioning system. And drive.

  This has the effect of being able to take measures against harmonics based on the actual amount of harmonics, including the harmonics generated by other devices 104 operating on the same power supply system, and the harmonic amount detection unit. There is an effect that the number 103 can be reduced.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Three-phase alternating current power supply 2 Three-phase rectifier 2a-2f Rectifier diode 3 Boost converter part 4 Boost reactor 5 Switching element 6 Backflow prevention element 7 Smoothing capacitor 8 Bus current detection part 9 Output voltage detection part 10 Switching control means 12 Inverter circuit 12a- 12f Switching element 13 Motor current detection means 14 Inverter drive means 15 Motor 16 Operation mode determination section 17 Operation stop status detection means 21 Bus current command value calculation section 22 On-duty calculation section 23 Drive pulse generation section 31 Operation mode setting section 32 Converter operation Stop determination unit 101 Air conditioner 102 Operation monitoring control unit 103 Harmonic amount detection unit 104 Other devices that operate with the same power supply system

Claims (8)

An air conditioning system comprising a plurality of air conditioners connected to a three-phase AC power source,
In each air conditioner,
A rectifier circuit for rectifying the three-phase AC power supply;
A step-up converter unit for stepping up the output voltage of the rectifier circuit;
An inverter unit that receives the output of the boost converter unit and drives a motor;
Load status detection means for detecting the load status of the air conditioner;
A plurality of operation modes can be set, and an operation mode determination unit that controls the operation of the boost converter unit based on the operation mode and the load situation;
Is provided,
In each of the operation mode determination units, the operation mode is set so that the circuit loss of the entire air conditioning system is minimized under the condition that the amount of harmonics generated from the air conditioning system is a predetermined value or less. Air conditioning system. The operation mode determination unit includes a harmonic reduction priority mode in which the boost converter unit is operated from a low load range of the air conditioner, and a loss reduction priority mode in which the boost converter unit is operated only in a high load range of the air conditioner. The air conditioning system according to claim 1, wherein any one of the operation modes can be set. 3. The air conditioning system according to claim 1, wherein the load condition detection unit detects at least one of an operating frequency of the motor, a bus current value of the boost converter unit, and a motor current value flowing through the motor. . The operation monitoring control part which monitors the operation stop condition of the air conditioner, and sets the operation mode of each air conditioner based on the operation stop condition of each air conditioner is provided. 4. The air conditioning system according to any one of 3. The said operation monitoring control part detects the model and number of said air conditioners, and sets the operation mode of each said air conditioner based on the relationship between the preset model and harmonic amount. Air conditioning system as described in. The operation monitoring control unit is configured to operate each air conditioner in such a manner that the circuit loss of the entire air conditioning system is minimized under a condition that the amount of harmonics generated from the air conditioning system is equal to or less than a predetermined value. The air conditioning system according to claim 4 or 5, wherein: A harmonic amount detection unit that detects the harmonic amount of each of the air conditioners,
The air conditioning system according to any one of claims 4 to 6, wherein the operation monitoring control unit sets an operation mode of each of the air conditioners based on a detection value of the harmonic amount detection unit. The three-phase AC power source includes a harmonic amount detection unit that detects the total harmonic amount of the air conditioning system,
The air conditioning system according to any one of claims 4 to 7, wherein the operation monitoring control unit sets an operation mode of each of the air conditioners based on a detection value of the harmonic amount detection unit.

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