Electric power conversion systems – Current conversion – With condition responsive means to control the output...
Patent
1997-08-07
1999-03-09
Riley, Shawn
Electric power conversion systems
Current conversion
With condition responsive means to control the output...
363127, 363 96, H02M 542
Patent
active
058809473
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control device for a PWM controlled converter which converts an AC power source voltage into a DC voltage.
2. Description of the Related Art
There are many devices which convert AC power to DC and the number of such devices is increasing. In this type of device, an AC power source voltage is converted into a DC voltage, and the converted DC voltage is used. In the AC to DC converting operation, reactive power and harmonics are generated, which causes some problems. To solve these problems, a PWM controlled converter has been proposed as a device for converting an AC power source voltage into a DC voltage.
FIG. 28 is a block diagram showing a conventional control device for a PWM controlled converter. The control device for a PWM controlled converter is as discussed in "Method for Controlling a P-phase Invertor not Using an Insulating Transformer", 1991 National Convention Record IEEE Japan, pp 5 to 80, or as disclosed in Japanese Patent Laid-Open Publication No. Hei. 3-212162.
In the figure, reference numeral 1 designates a 3-phase AC power source; numeral 2, a PWM controlled converter which converts AC power received from the 3-phase AC power source 1 into a DC voltage-by controlling the AC current of the received AC power, and outputs the converted DC voltage; numerals 201 to 206 designate switching elements which are transistors, IGBTs (insulated gate bipolar transistors) and the like; and 207 to 212 designate circulating diodes. Numeral 3 designates reactors connected between the 3-phase AC power source 1 and the PWM controlled converter 2; 4 designates a smoothing condenser for absorbing a pulsating component contained in an output current of the PWM controlled converter 2; 5 designates a load unit, such as an invertor or a resistive component; 6 designates a voltage setter for outputting a voltage setting signal for setting a DC voltage output from the PWM controlled converter 2; and 7b designates a voltage detecting circuit for detecting a DC voltage output from the PWM controlled converter 2.
Numeral 8 indicates a subtractor for calculating a deviation of a voltage detecting signal detected by and output from the voltage detecting circuit 7b from a voltage setting signal set by and output from the voltage setter 6; 9d designates a voltage controller which includes a proportional control calculating element and a proportional integration calculating element, and proportional integration (PI) controls a deviation of a voltage detecting signal output from the subtractor 8 from the voltage setting signal; 10 designates an AC voltage detector for detecting an AC voltage from the 3-phase AC power source 1; 11 designates a unit sine wave generator for generating R-phase and T-phase unit sine waves, which are synchronized with R-phase and T-phase voltages, from an AC voltage detecting signal detected by the AC voltage detector 10; 12 and 13 designate multipliers for multiplying a peak value instruction signal of an input current received from the voltage controller 9d by R-phase and T-phase unit sine wave signals received from the unit sine wave generator 11, and outputs R-phase and T-phase input current instruction signals.
Numerals 14 and 15 represent current detectors for detecting currents of R-phase and T-phase input to the PWM controlled converter 2; 16 and 17 represent subtractors for producing a deviation of an input current detecting signal of R-phase output from the current detector 14 from an input current instruction signal of R-phase output from the multiplier 12 and a deviation of an input current detecting signal of T-phase output from the current detector 15 from an input current instruction signal of T-phase output from the multiplier 13; 18b and 19b represent R- and T-phase current controllers which include proportional control calculating elements and proportional integration calculating elements, and proportional integration (PI) control the deviations of the T-phase input current detecting signals
REFERENCES:
patent: 4729082 (1988-03-01), Sato
patent: 5483435 (1996-01-01), Uchino
Ando Taro
Imanaka Akira
Mitsubishi Denki & Kabushiki Kaisha
Riley Shawn
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