Inverter control device and power conversion device

• US 8,736,220 B2
• Filed: 04/28/2009
• Issued: 05/27/2014
• Est. Priority Date: 04/28/2008
• Status: Active Grant

• Current Assignee: Daikin Industries Ltd
• Original Assignee: Daikin Industries Ltd
• Inventors: Ogawa, Takurou, Hibino, Hiroshi, Tomoe, Masanobu
• Primary Examiner(s): Ip, Paul
• Application Number:
  US12/989,799
• Publication Number:
  US 20110043150A1
• Time in Patent Office: 1,855 Days
• Field of Search: 318/801, 318/802, 318/805, 318/807, 318/254.1, 318/400.26, 318/400.01, 318/400.13, 318/439, 363/36, 363/37, 363/97, 363/41, 363/50
• US Class Current: 318/801
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02M 7/53873 with digital control
• CPC Class Codes: H02M 7/53876 based on synthesising a desired voltage vector via the selection of appropriate fundamental voltage vectors, and corresponding dwelling times
• CPC Class Codes: H02P 21/0003 Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control
• CPC Class Codes: H02P 21/05 specially adapted for damping motor oscillations, e.g. for reducing hunting

Abstract

A DC voltage value from a DC voltage detection section is input directly to a voltage correction section without passing through a compensator or a filter. Therefore, even when rapid voltage change occurs, such as short power interruptions, instantaneous voltage drop and return from instantaneous voltage drop, the voltage correction section can quickly perform the correction operation in response to the rapid voltage change. Since the amount of link resonance compensation is limited by the limitation section to a certain range, it is possible to prevent the amount of link resonance compensation from fluctuating excessively upon rapid voltage change. Since the amount of link resonance compensation which is limited by the limitation section to a certain range is input to one compensator that has an appropriate control band, among all control calculation sections, the response does not have to be unnecessarily fast, thus realizing a stable control.

Claims

1. An inverter control device for controlling an inverter which converts DC power supplied thereto via an LC filter including a reactor and a capacitor into AC power having an intended frequency and an intended voltage value, and supplies the converted power to an AC motor, wherein

a fluctuation component detection section configured to allow passage of a resonance frequency of the LC filter allows the inverter control device, within a predetermined frequency band of fluctuation of a DC voltage supplied to the inverter, to increase an inverter output voltage supplied from the inverter to a motor when the DC voltage increases, and to decrease the inverter output voltage when the DC voltage decreases, whereas the inverter control device is configured, within a frequency region that is an upper frequency region above the predetermined frequency band of the DC voltage and that is a frequency region of fluctuation when a power supply and a voltage rapidly change and a lower frequency region below the predetermined frequency band, to reduce fluctuation of the inverter output voltage due to fluctuation of the DC voltage, the predetermined frequency band of the DC voltage fluctuation including at least the resonance frequency of the LC filter, and being less than or equal to a frequency band of a feedback control in a current controller configured to control such that a current supplied to the AC motor follows a command value.

2. The inverter control device of claim 1, wherein

the predetermined frequency band is set to be less than a frequency of voltage ripples due to an AC power supply.

3. The inverter control device of claim 2, wherein

the inverter control device operates based on an amount of fluctuation of a predetermined frequency band component of the DC voltage so as to decrease a rate of increase in an inverter output voltage supplied from the inverter to the motor with respect to an amount of increase in the DC voltage, and to decrease a rate of decrease in the inverter output voltage with respect to an amount of decrease in the DC voltage, as the amount of fluctuation is larger.

4. The inverter control device of claim 1, wherein

the inverter control device operates based on an amount of fluctuation of a predetermined frequency band component of the DC voltage so as to decrease a rate of increase in an inverter output voltage supplied from the inverter to the motor with respect to an amount of increase in the DC voltage, and to decrease a rate of decrease in the inverter output voltage with respect to an amount of decrease in the DC voltage, as the amount of fluctuation is larger.

5. An inverter control device for controlling an inverter which converts DC power supplied thereto via an LC filter including a reactor and a capacitor into AC power having an intended frequency and an intended voltage value, and supplies the converted power to an AC motor, the inverter control device comprising:

control calculation sections for calculating an output voltage command;

an output voltage correction section for directly receiving a DC voltage value from a DC voltage detection section which detects a voltage of DC power supplied to the inverter so as to correct an output voltage command from the control calculation sections based on the DC voltage value;

a PWM calculation section for calculating a control signal for PWM-controlling the inverter based on an output voltage command from the output voltage correction section;

a fluctuation component detection section for detecting a fluctuation component (the fluctuation component at least not including a DC component and including a resonance frequency (f₀) component of the LC filter) of the DC voltage detected by the DC voltage detection section;

a link resonance compensation section for calculating an amount of compensation (amount of link resonance compensation) for reducing link resonance due to the LC filter based on the fluctuation component detected by the fluctuation component detection section;

a limitation section for limiting the amount of link resonance compensation to a predetermined range; and

a correction section for correcting, by the amount of link resonance compensation limited by the limitation section, an input command to one of the compensators in the control calculation section that has such a control band with which it is possible to control the resonance frequency (f₀) of the LC filter.

6. The inverter control device of claim 5, wherein

the input command to the one compensator in the control calculation section is a torque command or a current command.

7. The inverter control device of claim 5, wherein

a limitation value of the limitation section is set to a value that is smaller than an amplitude of a resonance component due to the LC filter where there is no correction by the amount of link resonance compensation.

8. The inverter control device of claim 5, wherein

the DC power supplied to the inverter is supplied by a converter which converts AC power from the AC power supply into DC power, and

the fluctuation component detection section includes a voltage ripple detection section for detecting the ripple component due to the AC power supply of the DC voltage detected by the DC voltage detection section, and removes the ripple component detected by the voltage ripple detection section from the fluctuation component.

9. The inverter control device of claim 5, wherein

the DC power supplied to the inverter is supplied by a converter which converts AC power from the AC power supply into DC power, and

the reactor and the capacitor of the LC filter are selected so that the resonance frequency (f₀) thereof is a frequency excluding frequencies that are integral multiples of the ripple component due to the AC power supply of a voltage of the DC power supplied to the inverter and frequencies in vicinity thereof.

10. The inverter control device of claim 5, wherein

the inverter control device further includes a voltage abnormality detection section for detecting voltage abnormality of the DC voltage detected by the DC voltage detection section, and

the limitation section adjusts the range of limitation based on a detection result of the voltage abnormality detection section.

11. The inverter control device of claim 5, wherein

the inverter control device further includes a voltage abnormality detection section for detecting voltage abnormality of the DC voltage detected by the DC voltage detection section, and

the link resonance compensation section adjusts the amount of link resonance compensation based on a detection result of the voltage abnormality detection section.

12. A power conversion device comprising:

a converter section for converting AC power from an AC power supply into DC power;

an LC filter including a reactor and a capacitor;

an inverter section, to which the DC power from the converter section is supplied via the LC filter, for converting the DC power into AC power having an intended frequency and an intended voltage value, and supplying the converted power to an AC motor; and

an inverter control section for controlling the inverter section, wherein

within a predetermined frequency band of fluctuation of a DC voltage supplied to the inverter, a fluctuation component detection section configured to allow passage of a resonance frequency of the LC filter allows the inverter control section to increase an inverter output voltage supplied from the inverter to a motor when the DC voltage increases, and to decrease the inverter output voltage when the DC voltage decreases, whereas, within a frequency region that is an upper frequency region above the predetermined frequency band of the DC voltage and that is a frequency region of fluctuation when a power supply and a voltage rapidly change and a lower frequency region below the predetermined frequency band, the inverter control section reduces fluctuation of the inverter output voltage due to fluctuation of the DC voltage, the predetermined frequency band of the DC voltage fluctuation including at least the resonance frequency of the LC filter, and being less than or equal to a frequency band of a feedback control in a current controller configured to control such that a current supplied to the AC motor follows a command value.

13. The power conversion device of claim 12, wherein

the predetermined frequency band is set to be less than a frequency of voltage ripples due to the AC power supply.

14. The power conversion device of claim 13, wherein

the power conversion device operates based on an amount of fluctuation of a predetermined frequency band component of the DC voltage so as to decrease a rate of increase in an inverter output voltage supplied from the inverter to the motor with respect to an amount of increase in the DC voltage, and to decrease a rate of decrease in the inverter output voltage with respect to an amount of decrease in the DC voltage, as the amount of fluctuation is larger.

15. The power conversion device of claim 12, wherein

the power conversion device operates based on an amount of fluctuation of a predetermined frequency band component of the DC voltage so as to decrease a rate of increase in an inverter output voltage supplied from the inverter to the motor with respect to an amount of increase in the DC voltage, and to decrease a rate of decrease in the inverter output voltage with respect to an amount of decrease in the DC voltage, as the amount of fluctuation is larger.

16. A power conversion device comprising:

a converter section for converting AC power from an AC power supply into DC power;

an LC filter including a reactor and a capacitor;

an inverter section, to which the DC power from the converter section is supplied via the LC filter, for converting the DC power into AC power having an intended frequency and an intended voltage value, and supplying the converted power to an AC motor; and

an inverter control section for controlling the inverter section, the inverter control section comprising;

a DC voltage detection section for detecting a voltage of the DC power supplied to the inverter section;

control calculation sections for calculating an output voltage command;

an output voltage correction section for directly receiving a DC voltage value detected by the DC voltage detection section so as to correct an output voltage command from the control calculation sections based on the DC voltage value;

a PWM calculation section for calculating a control signal for PWM-controlling the inverter section based on an output voltage command from the output voltage correction section;

a fluctuation component detection section for detecting a fluctuation component (the fluctuation component at least not including a DC component and including a resonance frequency (f₀) component of the LC filter) of the DC voltage detected by the DC voltage detection section;

a link resonance compensation section for calculating an amount of compensation (amount of link resonance compensation) for reducing link resonance due to the LC filter based on the fluctuation component detected by the fluctuation component detection section;

a limitation section for limiting the amount of link resonance compensation to a predetermined range; and

a correction section for correcting, by the amount of link resonance compensation limited by the limitation section, an input command to one of the compensators in the control calculation section that has such a control band with which it is possible to control the resonance frequency (f₀) of the LC filter.

17. The power conversion device of claim 16, wherein

the input command to the one compensator in the control calculation section is a torque command or a current command.

18. The power conversion device of claim 16, wherein

a limitation value of the limitation section is set to a value that is smaller than an amplitude of a resonance component due to the LC filter where there is no correction by the amount of link resonance compensation.

19. The power conversion device of claim 16, wherein

the fluctuation component detection section includes a voltage ripple detection section for detecting the ripple component due to the AC power supply of the DC voltage detected by the DC voltage detection section, and removes the ripple component detected by the voltage ripple detection section from the fluctuation component.

20. The power conversion device of claim 16, wherein

the reactor and the capacitor of the LC filter are selected so that the resonance frequency (f₀) thereof is a frequency excluding frequencies that are integral multiples of the ripple component due to the AC power supply of a voltage of the DC power supplied to the inverter section and frequencies in vicinity thereof.

21. The power conversion device of claim 16, wherein

the power conversion device further includes a voltage abnormality detection section for detecting voltage abnormality of the DC voltage detected by the DC voltage detection section, and

the limitation section adjusts the range of limitation based on a detection result of the voltage abnormality detection section.

22. The power conversion device of claim 16, wherein

the power conversion device further includes a voltage abnormality detection section for detecting voltage abnormality of the DC voltage detected by the DC voltage detection section, and

the link resonance compensation section adjusts the amount of link resonance compensation based on a detection result of the voltage abnormality detection section.

23. An air conditioner comprising the power conversion device of claim 16.