WO2024176384A1 - 電力変換装置及び空気調和機の室外機 - Google Patents

電力変換装置及び空気調和機の室外機 Download PDF

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Publication number
WO2024176384A1
WO2024176384A1 PCT/JP2023/006456 JP2023006456W WO2024176384A1 WO 2024176384 A1 WO2024176384 A1 WO 2024176384A1 JP 2023006456 W JP2023006456 W JP 2023006456W WO 2024176384 A1 WO2024176384 A1 WO 2024176384A1
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Prior art keywords
capacitor
power
load
conversion device
current
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Ceased
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PCT/JP2023/006456
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English (en)
French (fr)
Japanese (ja)
Inventor
章斗 田中
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to DE112023005839.3T priority Critical patent/DE112023005839T5/de
Priority to PCT/JP2023/006456 priority patent/WO2024176384A1/ja
Priority to JP2025502007A priority patent/JPWO2024176384A1/ja
Priority to CN202380094157.2A priority patent/CN120693783A/zh
Publication of WO2024176384A1 publication Critical patent/WO2024176384A1/ja
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into DC
    • H02M5/42—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into DC by static converters
    • H02M5/44—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into DC by static converters using discharge tubes or semiconductor devices to convert the intermediate DC into AC
    • H02M5/453—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into DC by static converters using discharge tubes or semiconductor devices to convert the intermediate DC into AC using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into DC by static converters using discharge tubes or semiconductor devices to convert the intermediate DC into AC using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M5/4585—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into DC by static converters using discharge tubes or semiconductor devices to convert the intermediate DC into AC using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/007—Plural converter units in cascade
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from DC input or output
    • H02M1/15—Arrangements for reducing ripples from DC input or output using active elements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
    • H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
    • H02M7/06—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
    • H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
    • H02M7/48—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current

Definitions

  • This disclosure relates to a power conversion device that rectifies AC power supplied from a commercial power source, converts it into AC power, and outputs it, and to an outdoor unit of an air conditioner that is equipped with the same.
  • a smoothing capacitor is used to smooth the power rectified by a rectifier that rectifies the AC current supplied from the commercial power source.
  • Patent Document 1 discloses a power conversion device that prevents a large current from flowing through the smoothing capacitor, thereby reducing the deterioration of the smoothing capacitor.
  • the output from the inverter to the device having a motor contains pulsation corresponding to the pulsation of the power flowing into the smoothing capacitor, thereby suppressing the current in the capacitor.
  • the output of the inverter tends to increase, and losses increase regardless of the magnitude of the capacitor load on the smoothing capacitor, resulting in a problem of reduced energy saving performance.
  • the present disclosure has been made in consideration of the above, and aims to obtain a power conversion device that suppresses deterioration of the smoothing capacitor and reduces the decline in energy-saving performance.
  • the power conversion device includes a rectifier that rectifies a first AC power supplied from a commercial power source, a capacitor connected to an output terminal of the rectifier, an inverter connected to both ends of the capacitor and converting the power output from the rectifier and the capacitor into a second AC power and outputting it to a load having a motor, and a control unit that performs capacitor load suppression control to suppress the current flowing to the capacitor by controlling the operation of the inverter so that the second AC power including pulsation corresponding to the pulsation of the power flowing from the rectifier to the capacitor is output from the inverter to the load.
  • the control unit estimates the capacitor load on the capacitor and determines whether or not to perform capacitor load suppression control based on the estimated value of the capacitor load.
  • the power conversion device disclosed herein has the effect of suppressing deterioration of the smoothing capacitor and suppressing a decrease in energy saving performance.
  • FIG. 1 is a diagram showing a configuration of a power conversion device according to a first embodiment
  • FIG. 13 shows an example of each current and a capacitor voltage of a capacitor in a smoothing unit when a control unit of a power conversion device according to the first embodiment smoothes a current output from a rectification unit in a smoothing unit and keeps a current flowing through an inverter constant
  • FIG. 13 is a diagram showing an example of each current and a capacitor voltage of a capacitor in a smoothing section when a control unit of a power conversion device according to a first embodiment controls an operation of an inverter to reduce a current flowing in a smoothing section
  • a flowchart showing the operation of a control unit included in the power conversion device according to the first embodiment.
  • FIG. 1 is a diagram showing an example of a hardware configuration for implementing a control unit included in a power conversion device according to a first embodiment;
  • FIG. 1 shows a configuration of a power conversion device according to a second embodiment.
  • FIG. 13 is a diagram showing a configuration of a power conversion device according to a third embodiment.
  • FIG. 13 is a diagram showing the operation of a power conversion device according to a fourth embodiment.
  • FIG. 13 is a diagram showing the operation of a power conversion device according to a fifth embodiment.
  • FIG. 13 is a diagram showing the operation of a power conversion device according to a sixth embodiment.
  • FIG. 23 is a diagram showing an example of a relationship between a capacitor current and a capacitor load suppression control amount of a power conversion device according to an eighth embodiment.
  • FIG. 13 is a diagram showing the configuration of an outdoor unit of an air conditioner according to a 9th embodiment.
  • Embodiment 1. 1 is a diagram showing a configuration of a power conversion device according to a first embodiment.
  • the power conversion device 1 is connected between a commercial power source 110 and a compressor 315.
  • the power conversion device 1 converts a first AC power of a power source voltage Vs supplied from the commercial power source 110 into a second AC power and supplies the second AC power to the compressor 315.
  • the second AC power may be different from the first AC power in at least one of the amplitude and the phase, or may be the same as the first AC power in both the amplitude and the phase.
  • the power conversion device 1 includes a voltage/current detection unit 501, a reactor 120, a rectification unit 130, a voltage detection unit 502, a smoothing unit 200, an inverter 310, current detection units 313a and 313b, and a control unit 400.
  • the compressor 315 is a load device that includes a motor 314 for driving the compressor, which receives power from the power conversion device 1.
  • the motor 314 included in the compressor 315 and the power conversion device 1 constitute the motor drive device 2.
  • the voltage/current detection unit 501 detects the voltage and current values of the first AC power supplied from the commercial power source 110, and outputs the detected voltage and current values to the control unit 400.
  • the voltage of the first AC power is the power source voltage Vs.
  • the reactor 120 is connected between the voltage/current detection unit 501 and the rectification unit 130.
  • the rectification unit 130 has a bridge circuit formed by rectification elements 131, 132, 133, and 134.
  • the rectification unit 130 rectifies the first AC power supplied from the commercial power source 110 and outputs it.
  • the rectification unit 130 performs full-wave rectification.
  • the voltage detection unit 502 detects the voltage value of the power rectified by the rectification unit 130, and outputs the detected voltage value to the control unit 400.
  • the smoothing unit 200 is connected to the output terminal of the rectification unit 130 via the voltage detection unit 502.
  • the smoothing unit 200 has a capacitor 210 which is a smoothing element and smoothes the power rectified by the rectification unit 130.
  • the capacitor 210 is, for example, an electrolytic capacitor or a film capacitor.
  • the capacitor 210 has a capacity to smooth the power rectified by the rectification unit 130, and the voltage generated in the capacitor 210 by the smoothing is not a full-wave rectified waveform of the commercial power source 110, but a waveform in which a voltage ripple according to the frequency of the commercial power source 110 is superimposed on a DC component, and does not pulsate significantly.
  • the frequency of this voltage ripple is a component twice as high as the frequency of the power source voltage Vs when the commercial power source 110 is single-phase, and a component six times as high as the frequency of the power source voltage Vs when the commercial power source 110 is three-phase.
  • the amplitude of this voltage ripple is determined by the capacitance of the capacitor 210.
  • the inverter 310 is connected to both ends of the capacitor 210 provided in the smoothing unit 200.
  • the inverter 310 has switching elements 311a, 311b, 311c, 311d, 311e, 311f and freewheeling diodes 312a, 312b, 312c, 312d, 312e, 312f.
  • the inverter 310 turns on and off the switching elements 311a, 311b, 311c, 311d, 311e, 311f under the control of the control unit 400, converts the power output from the rectifier unit 130 and the smoothing unit 200 into second AC power, and outputs it to the compressor 315.
  • Each of the current detection units 313a, 313b detects the current value of one phase of the three-phase current output from the inverter 310 and outputs the detected current value to the control unit 400.
  • the control unit 400 can calculate the current value of the remaining one phase output from the inverter 310 by acquiring the current values of two phases out of the three phase current values output from the inverter 310.
  • the motor 314 rotates according to the amplitude and phase of the second AC power supplied from the inverter 310, and performs a compression operation.
  • the compressor 315 is a hermetic compressor used in an air conditioner or the like, the load torque of the compressor 315 can often be considered as a constant torque load.
  • the reactor 120 may be arranged after the rectifier unit 130.
  • the voltage/current detection unit 501, the voltage detection unit 502, and the current detection units 313a and 313b may be collectively referred to as the detection units.
  • the voltage value and current value detected by the voltage/current detection unit 501, the voltage value detected by the voltage detection unit 502, and the current value detected by the current detection units 313a and 313b may be referred to as the detection values.
  • the control unit 400 obtains the voltage and current values of the first AC power from the voltage and current detection unit 501, obtains the voltage value of the power rectified by the rectification unit 130 from the voltage detection unit 502, and obtains the current value of the second AC power having the amplitude and phase converted by the inverter 310 from the current detection units 313a and 313b.
  • the control unit 400 uses the detection values detected by each detection unit to control the operation of the inverter 310, specifically, the on/off of the switching elements 311a, 311b, 311c, 311d, 311e, and 311f of the inverter 310.
  • the control unit 400 controls the operation of the inverter 310 so that the second AC power including pulsation corresponding to the pulsation of the power flowing from the rectification unit 130 to the capacitor 210 of the smoothing unit 200 is output from the inverter 310 to the compressor 315, which is a load.
  • the pulsation according to the pulsation of the power flowing into the capacitor 210 of the smoothing unit 200 is, for example, a pulsation that varies depending on the frequency of the pulsation of the power flowing into the capacitor 210 of the smoothing unit 200. In this way, the control unit 400 suppresses the current flowing into the capacitor 210 of the smoothing unit 200. Note that the control unit 400 does not need to use all the detection values acquired from each detection unit, and may perform control using only some of the detection values.
  • control unit 400 detects the amount of fluctuation in the voltage applied to capacitor 210 by removing the DC component of the voltage across capacitor 210 and extracting the AC component, and estimates the capacitor load. Based on the estimated value of the capacitor load, control unit 400 determines whether or not to implement capacitor load suppression control.
  • the capacitor load suppression control will be described later.
  • the load generated by the inverter 310 and the compressor 315 can be regarded as a constant load, and the following description will be given on the assumption that a constant current load is connected to the smoothing unit 200 in terms of the current output from the smoothing unit 200.
  • the current flowing from the rectifying unit 130 is current I1
  • the current flowing to the inverter 310 is current I2
  • the current flowing from the smoothing unit 200 is current I3.
  • the current I2 is a current obtained by combining the currents I1 and I3.
  • the current I3 can be expressed as the difference between the currents I2 and I1, that is, current I2-current I1.
  • the discharge direction of the smoothing unit 200 is the positive direction of the current I3, and the charge direction of the smoothing unit 200 is the negative direction. In other words, the current may flow into or out of the smoothing unit 200.
  • FIG. 2 is a diagram showing an example of each current and the capacitor voltage of the smoothing unit when the control unit of the power conversion device according to embodiment 1 smoothes the current output from the rectification unit in the smoothing unit and keeps the current flowing through the inverter constant.
  • current I1, current I2, current I3, and capacitor voltage Vdc are shown.
  • capacitor voltage Vdc is the voltage of capacitor 210 generated according to current I3.
  • the vertical axis of currents I1, I2, and I3 indicates the current value, and the vertical axis of capacitor voltage Vdc indicates the voltage value. All horizontal axes indicate time t. Note that, in reality, carrier components of inverter 310 are superimposed on currents I2 and I3, but are omitted here.
  • FIG. 3 is a diagram showing an example of each current and the capacitor voltage of the smoothing unit when the control unit of the power conversion device according to the first embodiment controls the operation of the inverter to reduce the current flowing through the smoothing unit.
  • the current I1, the current I2, the current I3, and the capacitor voltage Vdc are shown.
  • the capacitor voltage Vdc is the voltage of the capacitor 210 generated according to the current I3.
  • the vertical axis of the currents I1, I2, and I3 indicates the current value, and the vertical axis of the capacitor voltage Vdc indicates the voltage value.
  • the horizontal axis indicates time t.
  • the control unit 400 of the power conversion device 1 controls the operation of the inverter 310 so that the current I2 shown in FIG.
  • the control unit 400 controls the operation of the inverter 310 so that the current I2, which includes a pulsating current whose main component is the frequency component of the current I1, flows through the inverter 310.
  • the frequency component of current I1 is determined by the frequency of the AC current supplied from commercial power source 110 and the configuration of rectifier unit 130. Therefore, control unit 400 can set the frequency component of the pulsating current superimposed on current I2 to a component having a predetermined amplitude and phase.
  • the frequency component of the pulsating current superimposed on current I2 has a waveform similar to that of the frequency component of current I1. As control unit 400 brings the frequency component of the pulsating current superimposed on current I2 closer to the frequency component of current I1, it can reduce current I3 flowing through smoothing unit 200 and reduce the pulsating voltage generated in capacitor voltage Vdc.
  • the control unit 400 controls the operation of the inverter 310 to control the pulsation of the current flowing through the inverter 310, which is the same as controlling the pulsation of the first AC power output from the inverter 310 to the compressor 315.
  • the control unit 400 controls the operation of the inverter 310 so that the pulsation contained in the second AC power output from the inverter 310 is smaller than the pulsation of the power output from the rectifier unit 130.
  • the control unit 400 controls the amplitude and phase of the pulsation contained in the second AC power output from the inverter 310 so that the voltage ripple of the capacitor voltage Vdc, i.e., the voltage ripple generated in the capacitor 210, is smaller than the voltage ripple generated in the capacitor 210 when the second AC power output from the inverter 310 does not contain pulsation corresponding to the pulsation of the power flowing into the capacitor 210.
  • control unit 400 controls the amplitude and phase of the ripple contained in the second AC power output from the inverter 310 so that the current ripple flowing in and out of the capacitor 210 is smaller than the current ripple generated in the capacitor 210 when the second AC power output from the inverter 310 does not contain ripple corresponding to the ripple of the power flowing into the capacitor 210.
  • the AC current supplied from the commercial power source 110 is not particularly limited, and may be single-phase or three-phase.
  • the control unit 400 may determine the frequency component of the pulsating current superimposed on the current I2 according to the first AC power supplied from the commercial power source 110. Specifically, the control unit 400 controls the pulsating waveform of the current I2 flowing through the inverter 310 to a shape obtained by adding a DC component to a pulsating waveform having a main component of a frequency component twice the frequency of the first AC power when the first AC power supplied from the commercial power source 110 is single-phase, or a frequency component six times the frequency of the first AC power when the first AC power supplied from the commercial power source 110 is three-phase.
  • the pulsating waveform is, for example, the shape of the absolute value of a sine wave, or the shape of a sine wave.
  • the control unit 400 may add at least one frequency component of the components that are integer multiples of the sine wave frequency to the pulsating waveform as a predefined amplitude.
  • the pulsating waveform may also be a rectangular wave or a triangular wave.
  • the control unit 400 may set the amplitude and phase of the pulsating waveform to predetermined values.
  • the control unit 400 may calculate the amount of pulsation contained in the second AC power output from the inverter 310 using the voltage applied to the capacitor 210 or the current flowing through the capacitor 210, or may calculate the amount of pulsation contained in the second AC power output from the inverter 310 using the voltage or current of the first AC power supplied from the commercial power source 110.
  • FIG. 4 is a flowchart showing the operation of the control unit provided in the power conversion device according to embodiment 1.
  • the control unit 400 acquires detection values from each detection unit of the power conversion device 1.
  • the control unit 400 estimates the capacitor load.
  • the control unit 400 judges whether or not it is necessary to suppress the capacitor load. If the control unit 400 judges that it is necessary to suppress the capacitor load, the result is Yes in step S3, and in step S4, the control unit 400 performs the capacitor load suppression control.
  • the control unit 400 when the control unit 400 outputs the second AC power from the inverter 310 to the load, the control unit 400 includes a pulsation corresponding to the pulsation of the power flowing into the capacitor 210. Note that, if the capacitor load suppression control is already being performed, the control unit 400 continues the capacitor load suppression control. On the other hand, if the control unit 400 judges that it is not necessary to suppress the capacitor load, the result is No in step S3, and in step S5, the control unit 400 does not perform the capacitor load suppression control. That is, when the control unit 400 outputs the second AC power from the inverter 310 to the load, the control unit 400 does not include pulsation corresponding to the pulsation of the power flowing into the capacitor 210. Note that if the capacitor load suppression control is already not being performed, the control unit 400 continues not to perform the capacitor load suppression control.
  • FIG. 5 is a diagram showing an example of a hardware configuration realizing the control unit provided in the power conversion device according to the first embodiment.
  • the control unit 400 is realized by a processor 91 that executes various processes, a memory 92 that is a main memory, and a storage device 93 that stores information.
  • the processor 91 may be a calculation means such as an arithmetic unit, a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor).
  • the memory 92 may be a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory).
  • the storage device 93 stores a program for executing the capacitor load suppression control process.
  • the processor 91 reads the program stored in the storage device 93 into the memory 92 and executes it.
  • the processor 91 reads the program stored in the storage device 93 into the memory 92 and executes it, thereby realizing the function of the control unit 400.
  • the power conversion device 1 can reduce the capacity of the capacitor 210 mounted thereon, by reducing the pulsation voltage of the capacitor voltage Vdc, compared to the case where the control of the first embodiment is not performed.
  • the power conversion device 1 can reduce the number of capacitors 210 that configure the smoothing unit 200.
  • control unit 400 estimates the capacitor load and determines whether or not to implement capacitor load suppression control based on the estimated capacitor load value. Therefore, when the deterioration of the capacitor 210 is within an acceptable range when the capacitor load suppression control is not performed, it is possible to prevent losses from occurring due to a reduction in the capacitor current to suppress the capacitor load.
  • FIG. 6 is a diagram showing a configuration of a power conversion device according to the second embodiment.
  • the power conversion device 1 according to the second embodiment is different from the power conversion device 1 according to the first embodiment in that the power conversion device 1 according to the second embodiment includes a first current detection unit 601 and a second current detection unit 602.
  • the first current detection unit 601 is installed in the rectification unit 130. That is, the first current detection unit 601 is installed on the commercial power source 110 side rather than the capacitor 210.
  • the second current detection unit 602 is installed between the inverters 310. That is, the second current detection unit 602 is installed on the compressor 315 side, which is a load, rather than the capacitor 210.
  • the control unit 400 calculates the current flowing through the capacitor 210 from the difference between the current value detected by the first current detection unit 601 and the current value detected by the second current detection unit 602, and estimates the capacitor load.
  • the power conversion device 1 according to the second embodiment estimates the capacitor load based on the current flowing through the capacitor 210, which is calculated based on the difference between the current value detected by the first current detection unit 601 and the current value detected by the second current detection unit 602, and therefore can estimate the capacitor load more accurately than the power conversion device 1 according to the first embodiment. Therefore, the power conversion device 1 according to the second embodiment can more accurately determine whether or not it is necessary to perform capacitor load suppression control, and therefore can suppress deterioration of the capacitor 210.
  • the first current detection unit 601 and the second current detection unit 602 are generally installed in the power conversion device 1 for the purpose of motor control and control and protection of the boost circuit, so by estimating the capacitor load using the first current detection unit 601 and the second current detection unit 602 installed for motor control and control and protection of the boost circuit, it is possible to eliminate the need to newly add the first current detection unit 601 and the second current detection unit 602 for estimating the capacitor load.
  • Embodiment 3. 7 is a diagram showing a configuration of a power conversion device according to a third embodiment.
  • the power conversion device 1 according to the third embodiment is different from the power conversion device 1 according to the second embodiment in that the power conversion device 1 according to the third embodiment includes a first voltage detection circuit 701 and a second voltage detection circuit 702.
  • the first voltage detection circuit 701 is installed between the reactor 120 and the rectification unit 130. That is, the first voltage detection circuit 701 is installed on the commercial power source 110 side of the capacitor 210.
  • the second voltage detection circuit 702 is installed between the smoothing unit 200 and the inverter 310. That is, the second voltage detection circuit 702 is installed on the compressor 315 side, which is a load, of the capacitor 210.
  • the control unit 400 calculates a first power value from the current value detected by the first current detection unit 601 and the voltage value detected by the first voltage detection circuit 701. Therefore, the first current detection unit 601 and the first voltage detection circuit 701 form a first power detection unit 801.
  • the control unit 400 also calculates a second power value from the current value detected by the second current detection unit 602 and the voltage value detected by the second voltage detection circuit 702. Therefore, the second current detection unit 602 and the second voltage detection circuit 702 detect the second power detection unit 802.
  • the first power detection unit 801 is installed closer to the commercial power source 110 than the capacitor 210
  • the second power detection unit 802 is installed closer to the compressor 315, which is a load, than the capacitor 210.
  • the control unit 400 calculates the power consumption of the capacitor 210 based on the first power value and the second power value, and estimates the capacitor load.
  • the power conversion device 1 calculates the power consumption in the capacitor 210 based on a first power value calculated from the current value detected by the first current detection unit 601 and the voltage value detected by the first voltage detection circuit 701, and a second power value calculated from the current value detected by the second current detection unit 602 and the voltage value detected by the second voltage detection circuit 702, and estimates the capacitor load. Therefore, compared to the power conversion device 1 according to the second embodiment, the capacitor load can be estimated more accurately.
  • the control unit 400 performs the condenser load suppression control when the operation mode of the air conditioner is the normal operation mode, and does not perform the condenser load suppression control when the operation mode of the air conditioner is the energy saving operation mode.
  • FIG. 8 is a diagram showing the operation of the power conversion device according to embodiment 4.
  • the mode switching signal is a signal for switching the operation mode of the air conditioner, with a high level corresponding to the normal operation mode and a low level corresponding to the energy saving operation mode.
  • the mode switching signal is at a high level, and the air conditioner is operating in the normal operation mode. Therefore, at time t10, the control unit 400 is performing the capacitor load suppression control.
  • the control unit 400 changes the mode switching signal from a high level to a low level, and the air conditioner switches from the normal operation mode to the energy saving operation mode. Therefore, at time t11, the control unit 400 does not perform the capacitor load suppression control.
  • the capacitor load suppression control amount begins to decrease at time t11.
  • the control unit 400 changes the mode switching signal from low level to high level, switching the air conditioner from the energy saving operation mode to the normal operation mode. Therefore, at time t12, the control unit 400 starts the capacitor load suppression control, and the capacitor load suppression control amount begins to increase.
  • the capacitor load suppression control amount increases, the capacitor load decreases and the input power to the capacitor 210 increases.
  • the workload of the motor 314 on the refrigerant circuit of the air conditioner does not change depending on the capacitor load suppression control amount, so the air conditioning capacity of the air conditioner remains constant regardless of the capacitor load suppression control amount.
  • the power conversion device 1 switches whether or not to perform capacitor suppression control in accordance with the operation mode of the air conditioner. Therefore, when the input power to the capacitor 210 is small and the capacitor load can be kept small without performing the capacitor load suppression control, the capacitor load suppression control is not performed, thereby reducing losses in the motor 314 and improving energy saving performance.
  • Embodiment 5 The circuit configuration of the power conversion device 1 according to embodiment 5 is similar to that of the power conversion device 1 according to embodiment 1.
  • the power conversion device 1 according to embodiment 5 starts the capacitor load suppression control when the capacitor load exceeds a preset capacitor load upper threshold, and stops the capacitor load suppression control when the capacitor load becomes equal to or less than a preset capacitor load lower threshold.
  • FIG. 9 is a diagram showing the operation of the power conversion device according to embodiment 5.
  • the power conversion device 1 increases or decreases the capacitor load suppression control amount in accordance with the increase or decrease in the input power or the capacitor load until the capacitor load becomes equal to or less than the capacitor load lower threshold.
  • the control unit 400 performs the capacitor load suppression control.
  • the control unit 400 reduces the air conditioning capacity of the air conditioner. This reduces the input power of the capacitor 210 and also reduces the capacitor load.
  • the capacitor load becomes equal to or less than the capacitor load lower threshold. This causes the control unit 400 to not perform the capacitor load suppression control.
  • the capacitor load suppression control As the capacitor load suppression control is not performed, the capacitor load increases. At times t23 and t24, the capacitor load does not exceed the capacitor load upper threshold, so the control unit 400 continues not to perform the capacitor load suppression control. At time t25, the capacitor load exceeds the capacitor load upper threshold. Therefore, the control unit 400 performs the capacitor load suppression control, and the capacitor load suppression control amount starts to increase. As the capacitor load suppression control amount increases, the capacitor load decreases and the input power to the capacitor 210 increases. At time t26 and time t27, the capacitor load is not equal to or lower than the capacitor load lower limit threshold, so the control unit 400 continues to perform the capacitor load suppression control.
  • the power conversion device 1 according to the fifth embodiment can switch to an operation that prioritizes performance over suppressing the capacitor load when the capacitor load is low, thereby improving energy conservation.
  • whether or not to perform the capacitor load suppression control is switched on and off.
  • a threshold value serving as a target value for the capacitor load may be set in advance, and the capacitor load suppression control amount may be continuously changed according to the difference between the threshold value serving as the target value and the capacitor load.
  • Embodiment 6 The circuit configuration of the power conversion device 1 according to the sixth embodiment is the same as that of the power conversion device 1 according to the first embodiment.
  • Fig. 10 is a diagram showing the operation of the power conversion device according to the sixth embodiment.
  • the power conversion device 1 according to the sixth embodiment stops the control to suppress the capacitor load when the control amount of the control to suppress the capacitor load required to make the capacitor load equal to or less than the target load amount becomes equal to or less than a predetermined capacitor load suppression control amount threshold, and resumes the output of the control to suppress the capacitor load when the estimated value of the capacitor load exceeds a predetermined capacitor load threshold.
  • the control unit 400 is performing capacitor load suppression control, and the capacitor load is maintained at the target load amount.
  • the control unit 400 begins to reduce the air conditioning capacity of the air conditioner. Therefore, from time t31, the capacitor load suppression control amount also decreases in line with the decrease in air conditioning capacity.
  • the capacitor load suppression control amount becomes equal to or less than the predetermined capacitor load suppression control amount threshold. Therefore, the control unit 400 stops the capacitor load suppression control. Therefore, at time t32, the capacitor load suppression control amount decreases to 0.
  • the capacitor load suppression control amount decreases, the capacitor load increases, but the input power to the capacitor 210 decreases because the loss of the motor 314 is improved.
  • the capacitor load does not exceed the predetermined capacitor load threshold, so the control unit 400 continues to stop the capacitor load suppression control.
  • the capacitor load exceeds the predetermined capacitor load threshold, so the control unit 400 resumes the capacitor load suppression control, and the capacitor load suppression control amount increases.
  • the capacitor load suppression control amount increases, the capacitor load decreases to the target load amount, and the input power to the capacitor 210 increases.
  • the capacitor load suppression control amount is not equal to or less than the predetermined capacitor load suppression control amount threshold, so the control unit 400 continues the capacitor load suppression control.
  • the power conversion device 1 controls the capacitor load so that it does not exceed a predetermined capacitor load threshold, but allows the capacitor load to deteriorate to a certain value when the capacitor load falls below a certain value, and by setting the control amount to the minimum necessary, it is possible to improve energy saving performance in an operating state where the capacitor load is low.
  • Embodiment 7 The circuit configuration of the power conversion device 1 according to the seventh embodiment is similar to that of the power conversion device 1 according to the first embodiment.
  • the power conversion device 1 according to the seventh embodiment continuously changes the capacitor load suppression control amount so that the lifetime of the capacitor 210 estimated from the capacitor load does not fall below a preset period.
  • the life of a capacitor is known to follow Arrhenius' law. For this reason, the life of a capacitor can generally be calculated from the ambient temperature of the capacitor, the voltage applied to the capacitor, and the amount of capacitor current caused by heat generation by the capacitor, in addition to constants determined by the capacitor's specifications.
  • the ambient temperature of capacitor 210 can be calculated by adding the temperature difference between the ambient temperature of capacitor 210 and the outdoor temperature detected by an air conditioner, which is confirmed in a pre-evaluation or the like, based on the outdoor temperature.
  • the voltage applied to capacitor 210 can be calculated from the detection value of voltage detection unit 502.
  • the amount of capacitor current can be calculated from the amount of fluctuation in the voltage applied to the capacitor, or from the difference between the amount of system power supply current and the amount of motor current.
  • the power conversion device 1 according to embodiment 7 does not implement capacitor load suppression control when it is estimated that the life of the capacitor 210 will not fall below the preset period, and implements capacitor load suppression control only when it is estimated that the life of the capacitor 210 will fall below the preset period. Therefore, when it is predicted that the life of the capacitor 210 will not fall below the preset period, the life of the capacitor 210 is allowed to shorten to the preset period and the capacitor load suppression control is not implemented, thereby suppressing the decrease in energy saving performance caused by performing the capacitor load suppression control. As a result, the power conversion device 1 according to embodiment 7 can ensure that the life of the capacitor 210 is longer than the preset period while suppressing the decrease in energy saving performance.
  • Embodiment 8 The circuit configuration of the power conversion device 1 according to the eighth embodiment is the same as that of the power conversion device 1 according to the second embodiment.
  • the control unit 400 breaks down the capacitor current into frequency components, and changes the control amount of the capacitor load suppression control so that the root of the sum of the squares of the frequency component twice the power supply voltage Vs or the component that is an integer multiple of the power supply voltage Vs does not exceed a predetermined constant value.
  • the control unit 400 allows the root of the sum of the squares of the frequency component twice the power supply voltage Vs or the component that is an integer multiple of the power supply voltage Vs to increase up to a predetermined constant value, and sets the capacitor load suppression control amount to a minimum required amount.
  • ripple current I R is calculated by the following formula (1).
  • I R is the effective value [Ams] of the ripple current at a specified frequency
  • I X1 to I XN are the effective values [Ams] of the ripple current at each frequency
  • K 1 to K N are frequency correction coefficients at each frequency. Since the frequency correction coefficients at each of the above frequency components differ for each capacitor component used as capacitor 210, control unit 400 stores information on the component specifications of the capacitor component used as capacitor 210 in advance.
  • the control unit 400 uses the bandpass filters 401 and 402 to decompose the capacitor current into a frequency component twice the power supply voltage Vs and a component that is an integer multiple of the frequency component twice the power supply voltage Vs.
  • the component that is an integer multiple of the frequency component twice the power supply voltage Vs is, for example, a frequency component four times the power supply voltage Vs.
  • the control unit 400 then divides the frequency component twice the power supply voltage Vs by a frequency correction coefficient using a divider 403, and divides the component that is an integer multiple of the frequency component twice the power supply voltage Vs by a frequency correction coefficient using a divider 404.
  • the control unit 400 then calculates the root of the sum of squares of the frequency component twice the power supply voltage Vs divided by the frequency correction coefficient and the component that is an integer multiple of the frequency component twice the power supply voltage Vs divided by the frequency correction coefficient using an adder 405. Then, the control unit 400 calculates the difference between the sum calculated by the adder 405 and a preset threshold value using the subtractor 406, and changes the capacitor load suppression control amount based on the calculation result of the subtractor 406. Note that the sum calculated by the adder 405 used in the processing by the subtractor 406 is not an instantaneous value but an average value over a preset time period, thereby preventing the capacitor load suppression control amount from being frequently changed.
  • the power conversion device 1 varies the control amount based on the magnitude of the root sum of the squares of the frequency component twice the power supply voltage Vs, or the frequency component twice the power supply voltage Vs and its integer multiple, among the multiple frequency components contained in the capacitor current, for which the capacitor load can be efficiently suppressed by control. This makes it possible to prevent a sudden increase in the control amount for preventing the capacitor current from exceeding a certain value, which would result in a loss of energy saving performance, when the total capacitor load increases due to other frequency components that cannot be efficiently suppressed by control.
  • the capacitor current is decomposed into a frequency component that is twice the power supply voltage Vs and a component that is an integer multiple of the frequency component that is twice the power supply voltage Vs, but the capacitor current may be decomposed into a frequency component that is an integer multiple of the power supply voltage Vs.
  • the capacitor current may also be decomposed into a frequency component that is an integer multiple of the power supply voltage Vs and a frequency component of the rotation speed of the compressor 315, or the capacitor current may be decomposed into a frequency component that is an integer multiple of the power supply voltage Vs and a frequency component that is twice the control period of the inverter 310 or the converter.
  • the capacitor current may also be decomposed into at least one of a frequency component that is an integer multiple of the power supply voltage Vs, a frequency component of the rotation speed of the compressor 315, and a frequency component that is twice the control period of the inverter 310 or the converter.
  • Embodiment 9. 12 is a diagram showing the configuration of an outdoor unit of an air conditioner according to embodiment 9.
  • An outdoor unit 900 of an air conditioner according to embodiment 9 includes the power conversion device 1 according to any one of embodiments 1 to 8.
  • the outdoor unit 900 of the air conditioner is equipped with a compressor 315 incorporating a motor 314 as shown in the first to eighth embodiments, a four-way valve 902, an indoor heat exchanger 906, an expansion valve 908, and an outdoor heat exchanger 910, all of which are connected via refrigerant piping 912.
  • a compression mechanism 904 that compresses the refrigerant, and a motor 314 that operates the compression mechanism 904.
  • the outdoor unit 900 can perform heating or cooling operation by switching the four-way valve 902.
  • the compression mechanism 904 is driven by a variable speed controlled motor 314.
  • the refrigerant is pressurized by the compression mechanism 904 and sent out, passes through the four-way valve 902, the indoor heat exchanger 906, the expansion valve 908, the outdoor heat exchanger 910, and the four-way valve 902, and returns to the compression mechanism 904.
  • the refrigerant is pressurized by the compression mechanism 904 and sent out, passes through the four-way valve 902, the outdoor heat exchanger 910, the expansion valve 908, the indoor heat exchanger 906, and the four-way valve 902, and returns to the compression mechanism 904.
  • the indoor heat exchanger 906 acts as a condenser to release heat, and the outdoor heat exchanger 910 acts as an evaporator to absorb heat.
  • the outdoor heat exchanger 910 acts as a condenser to release heat, and the indoor heat exchanger 906 acts as an evaporator to absorb heat.
  • the expansion valve 908 reduces the pressure of the refrigerant to expand it.
  • 1 Power conversion device 2 Motor drive device, 91 Processor, 92 Memory, 93 Storage device, 110 Commercial power source, 120 Reactor, 130 Rectification section, 131, 132, 133, 134 Rectification element, 200 Smoothing section, 210 Capacitor, 310 Inverter, 311a, 311b, 311c, 311d, 311e, 311f Switching element, 312a, 312b, 312c, 312d, 312e, 312f Freewheeling diode, 313a, 313b Current detection section, 314 Motor, 315 Compressor, 400 control unit, 401, 402 band pass filters, 403, 404 divider, 405 adder, 406 subtractor, 501 voltage current detection unit, 502 voltage detection unit, 601 first current detection unit, 602 second current detection unit, 701 first voltage detection circuit, 702 second voltage detection circuit, 801 first power detection unit, 802 second power detection unit, 900 outdoor unit, 902 four-way valve, 904 compression mechanism, 90

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PCT/JP2023/006456 2023-02-22 2023-02-22 電力変換装置及び空気調和機の室外機 Ceased WO2024176384A1 (ja)

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WO2019082316A1 (ja) * 2017-10-25 2019-05-02 東芝三菱電機産業システム株式会社 電力変換装置
JP2020167747A (ja) * 2017-07-31 2020-10-08 日本電産株式会社 電源装置、駆動装置、制御方法、及びプログラム

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JP6444453B2 (ja) * 2017-06-01 2018-12-26 三菱電機株式会社 電力変換装置の制御装置および制御方法
JP2021118600A (ja) * 2020-01-24 2021-08-10 日本電産株式会社 電源装置、制御方法、及びプログラム
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WO2022091184A1 (ja) * 2020-10-26 2022-05-05 三菱電機株式会社 電力変換装置、モータ駆動装置および冷凍サイクル適用機器
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JP2020167747A (ja) * 2017-07-31 2020-10-08 日本電産株式会社 電源装置、駆動装置、制御方法、及びプログラム
WO2019082316A1 (ja) * 2017-10-25 2019-05-02 東芝三菱電機産業システム株式会社 電力変換装置

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