Power converter
A power converter includes a rectifier section, an inverter section, a capacitance element connected between inverter section input ends, an inductance element forming part of an LC filter with the capacitance element, a voltage detector detecting an inductance element voltage, and a controller controlling the inverter section based on the detected voltage. The LC filter has a resonance frequency set such that ripple current components contained in DC current outputted from the rectifier section passes through, and current components of a frequency equal to a carrier frequency of the inverter section are dampened. The controller controls the inverter section so that a transfer characteristic of input voltage of the inverter section versus the DC voltage from the rectifier section becomes a damping characteristic given by a phase lead element and a second-order lag element connected in series, and a damping coefficient of the transfer characteristic is set larger than 1.
1. A power converter comprising:
a rectifier section configured to rectify a single-phase or polyphase AC voltage into a DC voltage and to output the DC voltage;
an inverter section of PWM control configured to convert the DC voltage outputted from the rectifier section into an AC voltage and to output the AC voltage;
a capacitance element connected between input ends of the inverter section;
an inductance element forming part of an LC filter in combination with the capacitance element;
a voltage detector configured to detect a voltage across the inductance element; and
a controller configured to control the inverter section based on a voltage across the inductance element detected by the voltage detector,
the LC filter having a resonance frequency set such that
ripple current components contained in DC current outputted from the rectifier section passes therethrough and
current components of a frequency equal to a carrier frequency of the inverter section are dampened, and
the controller being further configured to control the inverter section so that
a transfer characteristic of input voltage of the inverter section versus the DC voltage from the rectifier section becomes a damping characteristic given by a phase lead element and a second-order lag element connected in series, and
a damping coefficient of the transfer characteristic of the input voltage of the inverter section versus the DC voltage from the rectifier section is larger than 1, and
the controller being further configured to have a characteristic difference between a resonance suppression system for suppression of resonance due to the LC filter and a harmonic suppression system for suppression of harmonics due to an output-side inductive load of the inverter section so that cut-off frequencies of the resonance suppression system and the harmonic suppression system are different from each other.
2. The power converter as claimed in claim 1 , wherein
the controller includes
a first feedback loop configured to control a current flowing through the inductance element by negatively feeding back a voltage across the inductance element detected by the voltage detector to an input current of the inverter section, and
a second feedback loop configured to control a current flowing through the capacitance element by positively feeding back the input voltage of the inverter section to the input current of the inverter section, and
a first gain of the first feedback loop and a second gain of the second feedback loop are set on that the transfer characteristic of the input voltage of the inverter section versus the DC voltage from the rectifier section and a transfer characteristic of a DC current flowing through the inductance element versus the input current of the inverter section become predetermined transfer characteristics, respectively.
3. The power converter as claimed in claim 2 , wherein
the controller
a ripple removal section configured to remove ripple voltage components contained in the DC voltage outputted from the rectifier section in the second feedback loop of the input voltage of the inverter section.
4. The power converter as claimed in claim 3 , wherein
the first gain of the first feedback loop of the voltage across the inductance element detected by the voltage detector is set approximately to zero.
5. The power converter as claimed in claim 3 , further comprising:
a resistor connected in parallel to both ends of the inductance element,
the first gain of the first feedback loop of the voltage across the inductance element detected by the voltage detector is set by a resistance value of the resistor.
6. The power converter as claimed in claim 2 , wherein
the first gain of the first feedback loop of the voltage across the inductance element detected by the voltage detector is set approximately to zero.
7. The power converter as claimed in claim 6 , further comprising:
a resistor connected in parallel to both ends of the inductance element,
the first gain of the first feedback loop of the voltage across the inductance element detected by the voltage detector is set by a resistance value of the resistor.
8. The power converter as claimed in claim 2 , further comprising:
a resistor connected in parallel to both ends of the inductance element,
the first gain of the first feedback loop of the voltage across the inductance element detected by the voltage detector is set by a resistance value of the resistor.
9. The power converter as claimed claim 1 , wherein
a capacitance of the capacitance element is C,
an inductance of the inductance element is L,
a standard capacitance of the capacitance element is C R ,
an inductance of the inductance element is L R , and
the inductance L R is determined by the standard capacitance C R of the capacitance element and the resonance frequency of the LC filter such that L/C<L R /C R .
10. The power converter as claimed in claim 1 , wherein
a capacitance of the capacitance element is C,
an inductance of the inductance element is L,
a standard capacitance of the capacitance element is C R ,
an inductance of the inductance element is L R , and
the inductance L R is determined by the standard capacitance C R of the capacitance element and the resonance frequency of the LC filter such that L/C>L R /C R .
11. The power converter as claimed in claim 1 , wherein
the inductance element is connected between one output end of the rectifier section and one input end of the inverter section.
12. The power converter as claimed in claim 1 , wherein
the inductance element is connected between one output end of an AC power supply configured to supply the AC voltage and one input end of the rectifier section.
13. A power converter comprising:
a rectifier section configured to rectify a single-phase or polyphase AC voltage into a DC voltage and to output the DC voltage;
an inverter section of PWM control configured to convert the DC voltage outputted from the rectifier section into an AC voltage and to output the AC voltage;
a capacitance element connected between input ends of the inverter section;
an inductance element forming part of an LC filter in combination with the capacitance element;
a voltage detector configured to detect a voltage across the inductance element; and
a controller configured to control the inverter section based on a voltage across the inductance element detected by the voltage detector,
the LC filter having a resonance frequency set such that
ripple current components contained in DC current outputted from the rectifier section passes therethrough and
current components of a frequency equal to a carrier frequency of the inverter section are dampened, and
the controller being further configured to control the inverter section so that
a transfer characteristic of input voltage of the inverter section versus the DC voltage from the rectifier section becomes a damping characteristic given by a phase lead element and a second-order lag element connected in series, and
a damping coefficient of the transfer characteristic of the input voltage of the inverter section versus the DC voltage from the rectifier section is larger than 1;
the controller including
a first feedback loop tired to control a current flowing through the inductance element by negatively feeding back a voltage across the inductance element detected by the voltage detector to an input current of the inverter section, and
a second feedback loop configured to control a current flowing through the capacitance element by positively feeding back the input voltage of the inverter section to the input current of the inverter section, and
a first gain of the first feedback loop and a second gain of the second feedback loop being set so that the transfer characteristic of the input voltage of the inverter section versus the DC voltage from the rectifier section and a transfer characteristic of a DC current flow through the inductance element versus the input current of the inverter section become predetermined transfer characteristics, respectively, and
the first gain of the first feedback loop and the second gain of the second feedback loop being set so that a cut-off frequency of the transfer characteristic of the input voltage of the inverter section versus the DC voltage from the rectifier section and a lower-side cut-off frequency of the transfer characteristic of the DC current flowing through the inductance element versus the input current of the inverter section become equal to each other.
14. The power converter as claimed in claim 13 , wherein
the controller a ripple removal section configured to remove ripple voltage components contained in the DC voltage outputted from the rectifier section in the second feedback loop of the input voltage of the inverter section.
15. The power converter as claimed in claim 13 , wherein
the first gain of the first feedback loop of the voltage across the inductance element detected by the voltage detector is set approximately to zero.
16. The power converter as claimed in claim 13 , further comprising:
a resistor connected in parallel to both ends of the inductance element,
the first gain of the first feedback loop of the voltage across the inductance element detected by the voltage detector is set by a resistance value of the resistor.
17. A power converter comprising:
a rectifier section configured to rectify a single-phase or polyphase AC voltage into a DC voltage and to output the DC voltage:
an inverter section of PWM control configured to convert the DC voltage outputted from the rectifier section into an AC volt e and to output the AC voltage;
a capacitance element connected between input ends of the inverter section;
an inductance element forming part of an LC filter in combination with the capacitance element;
a voltage detector configured to detect a voltage across the inductance element; and
a controller configured to control the inverter section based on a voltage across the inductance element detected by the voltage detector,
the LC filter having a resonance frequency set such that
ripple current components contained in DC current outputted from the rectifier section passes therethrough and
current components of a frequency equal to a carrier frequency of the inverter section are dampened, and
the controller being further configured to control the inverter section so that
a transfer characteristic of input voltage of the inverter section versus the DC voltage from the rectifier section becomes a damping characteristic given by phase lead element and a second-order lag element connected in series, and
a damping coefficient of the transfer characteristic of the input voltage of the inverter section versus the DC voltage from the rectifier section is larger than 1, and
the controller being further configured to control the inverter section so that
a cut-off frequency of the transfer characteristic of the input voltage of the inverter section versus the DC voltage from the rectifier section becomes higher than a resonance frequency of the LC filter and
a cut-off frequency of a transfer characteristic of a DC current flowing through the inductance element versus the input current of the inverter section becomes lower than the resonance frequency of the LC filter.
18. A power converter comprising:
rectifier section configured rectify a single-phase or polyphase AC voltage into a DC voltage and to output the DC voltage;
an inverter section of PWM control configured to convert the DC voltage outputted from the rectifier section into an AC voltage and to output the AC voltage;
a capacitance element connected between input ends of the inverter section;
an inductance element forming part of an LC filter in combination with the capacitance element;
a voltage detector configured to detect a voltage across the inductance element; and
a controller configured to control the inverter section based on a voltage across the inductance element detected by the voltage detector,
the LC filter having a resonance frequency set such that
ripple current components contained in DC current outputted from the rectifier section passes therethrough and
current components of a frequency equal to a carrier frequency of the inverter section are dampened, and
the controller being further configured to control the inverter section so that
a transfer characteristic of input voltage of the inverter section versus the DC voltage from the rectifier section becomes a damping characteristic given by a phase lead element and a second-order lag element connected in series, and
a damping coefficient of the transfer characteristic of the input voltage of the inverter section versus the DC voltage from the rectifier section is larger than 1, and
a cut-off frequency of a transfer characteristic of a DC current flowing through the inductance element versus input current of the inverter section being larger than a repetition frequency of ripple voltage components contained in the DC voltage outputted from the rectifier section.
19. A power converter comprising:
a rectifier section configured to rectify a single-phase or polyphase AC voltage into a DC voltage and to output the DC voltage;
an inverter section of PWM control configured to convert the DC voltage outputted from the rectifier section into an AC voltage and to output the AC voltage;
a capacitance element connected between input ends of the inverter section;
an inductance element forming part of an LC filter in combination with the capacitance element;
a voltage detector configured to detect a voltage across the inductance element; and
a controller configured to control the inverter section based on a voltage across the inductance element detected by the voltage detector,
the LC filter having a resonance frequency set such that
ripple current components contained in DC current outputted from the rectifier section passes therethrough and
current components of a frequency equal to a carrier frequency of the inverter section are dampened, and
the controller being further configured to control the inverter section so that
a transfer characteristic of input voltage of the inverter section versus the DC voltage from the rectifier section becomes a damping characteristic given by a phase lead element and a second-order lag element connected in series, and
a damping coefficient of the transfer characteristic of the input voltage of the inverter section versus the DC voltage from the rectifier section is larger than 1, and
a cut-off frequency of a transfer characteristic of a DC current flowing through the inductance element versus input current of the inverter section being smaller than a repetition frequency of ripple voltage components contained in the DC voltage outputted from the rectifier section.