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US5285145A
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Current-limit system for voltage-type inverter
Assignee: Fuji Electric Co Ltd
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Filing: 1989-08-30
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Granted: 1994-02-08
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Expires: 2009-08-30
Abstract
Abstract PCT No. PCT/JP89/00889 Sec. 371 Date Apr. 24, 1990 Sec. 102(e) Date Apr. 24, 1990 PCT Filed Aug. 30, 1989 PCT Pub. No. WO90/02442 PCT Pub. Date Mar. 8, 1990.A current transformer (4) detects the output currents of a voltage-type inverter (INV), and comparators (6) check whether the outputs from the current transformer exceed a predetermined limit value. The detected output currents are fed to a vector analyzer (8) to determine the location of the output current vector. A zone determining circuit (9) determines the location of the current vector in the zones. An output pattern generating circuit (10) responds to the output from the zone determining circuit (9) and provides a switching pattern corresponding to the voltage vector nearest to a vector having the direction opposite to that of the output current vector. A selector (2), being controlled by the comparator (6), selects a switching pattern from the output pattern generating circuit and provides it to the inverter (INV), when the comparator (6) detects that the magnitude of the current vector exceeds the predetermined limit value. The rate of change of the output current vector works so as to reduce the current regardless of whether the motor (IM) (a load of the inverter) is to be driven or braked, regardless of the location of the counter-electromotive force vector or the location of the voltage vector selected at that timing when the current limit enters into action. This ensures that the output current of the inverter (INV) will be reduced.
Inventors
- 👤 Hirofumi Minowa
- 👤 Masaru Yamazoe
- 👤 Takao Yanase
- 👤 Shin'ichi Ishii
- 👤 Yoshinobu Nagao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:48
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02P27/08; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; H02M7/5387; H02M7/53871; H02M7/53873; H02M7/53875; H02M7/53876; H02P21/00; H02P27/047
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
294 words
A current limit system for use in a voltage-type inverter comprising: first means for detecting the magnitude of an output current vector of the voltage-type inverter to determine if the magnitude exceeds a predetermined limit value, said first means including: detecting means for detecting the output currents of said voltage-type inverter; and comparator means for comparing said output currents detected by said detecting means with said predetermined limit value; second mans for determining the location of said output current vector; sixth means for determining the location of the counterelectromotive force vector of a load of said voltage-type inverter according to the output current and output voltage of said voltage-type inverter; and seventh means for selecting a voltage vector which reduces said output current in such a way that the rate of reduction of said output current is minimized on the basis of the locations of said output current vector and counter electromotive force vector, and for enabling said voltage-type inverter to produce said selected voltage vector as the output, when the magnitude of said output current vector exceeds its limit value, said seventh means including: determination means for determining the location of said output current vector and for providing a rotation angle signal that specifies the amount of rotation necessary for the counter-electromotive force vector to rotate with regard to the determined location of said output current vector; counter-electromotive force vector determination means for determining the location of said counter-electromotive force vector according to said counter-electromotive force vector provided by said sixth means and said rotation angle signal provided by said determining means; and output pattern generating means for producing one of the predetermined switching patterns in response to said rotation angle signal and said determination output from said counter-electromotive force vector determination means.
Claim 2
Dependent Claim
294 words
A current limit system for use in a voltage-type inverter comprising: first means for detecting the magnitude of an output current vector of the voltage-type inverter to determine if the magnitude exceeds a predetermined limit value, said first means including: detecting means for detecting the output currents of said voltage-type inverter; and comparator means for comparing said output currents detected by said detecting means with said predetermined limit value; second mans for determining the location of said output current vector; sixth means for determining the location of the counterelectromotive force vector of a load of said voltage-type inverter according to the output current and output voltage of said voltage-type inverter; and seventh means for selecting a voltage vector which reduces said output current in such a way that the rate of reduction of said output current is minimized on the basis of the locations of said output current vector and counter electromotive force vector, and for enabling said voltage-type inverter to produce said selected voltage vector as the output, when the magnitude of said output current vector exceeds its limit value, said seventh means including: determination means for determining the location of said output current vector and for providing a rotation angle signal that specifies the amount of rotation necessary for the counter-electromotive force vector to rotate with regard to the determined location of said output current vector; counter-electromotive force vector determination means for determining the location of said counter-electromotive force vector according to said counter-electromotive force vector provided by said sixth means and said rotation angle signal provided by said determining means; and output pattern generating means for producing one of the predetermined switching patterns in response to said rotation angle signal and said determination output from said counter-electromotive force vector determination means.
Claim 3
Dependent Claim
400 words
A current limit system for use in a voltage-type inverter comprising: first means for determining the magnitude of an output current vector of the voltage-type inverter to determine if the magnitude exceeds a predetermined limit value, said first means including; detecting means for detecting the output currents of said voltage-type inverter; and comparator means for comparing said output currents detected by said detecting means with said predetermined limit value; second means for determining the location of said output current vector; third means for selecting a voltage vector wherein the location of said selected voltage vector is closest to a vector having the opposite direction to said output current vector determined by said second means, and for enabling said voltage-type inverter to produce selected voltage vector as the output, when the magnitude of said output current vector exceeds said predetermined limit value; fourth means for producing a particular switching pattern in response to an inputted voltage command; and fifth means for selecting, in response to the detecting output provided by the first means, either the switching pattern corresponding to the voltage vector selected by said third means or the switching pattern for said fourth means, and outputting said selected switching pattern; sixth means for determining the location of the counterelectromotive force vector of a load of said voltage-type inverter according to the output current and output voltage of said voltage-type inverter; and seventh means for selecting a voltage vector which reduces said output current in such a way that the rate of reduction of said output current is minimized on the basis of the locations of said output current vector and counter electromotive force vector, and for enabling said voltage-type inverter to produce said selected voltage vector as the output, when the magnitude of said output current vector exceeds its limit value, said seventh means including: determination means for determining the location of said output current vector and for providing a rotation angle signal that specifies the amount of rotation necessary for the counter-electromotive force vector to rotate with regard to the determined location of said output current vector; counter-electromotive force vector determination force vector provided by said sixth means and said rotation angle signal provided by said determination means; and output pattern generating means for producing one of the predetermined switching patterns in response to said rotation angle signal and said determination output from said counter-electromotive force vector determination means.
Claim 4
Dependent Claim
400 words
A current limit system for use in a voltage-type inverter comprising: first means for determining the magnitude of an output current vector of the voltage-type inverter to determine if the magnitude exceeds a predetermined limit value, said first means including; detecting means for detecting the output currents of said voltage-type inverter; and comparator means for comparing said output currents detected by said detecting means with said predetermined limit value; second means for determining the location of said output current vector; third means for selecting a voltage vector wherein the location of said selected voltage vector is closest to a vector having the opposite direction to said output current vector determined by said second means, and for enabling said voltage-type inverter to produce selected voltage vector as the output, when the magnitude of said output current vector exceeds said predetermined limit value; fourth means for producing a particular switching pattern in response to an inputted voltage command; and fifth means for selecting, in response to the detecting output provided by the first means, either the switching pattern corresponding to the voltage vector selected by said third means or the switching pattern for said fourth means, and outputting said selected switching pattern; sixth means for determining the location of the counterelectromotive force vector of a load of said voltage-type inverter according to the output current and output voltage of said voltage-type inverter; and seventh means for selecting a voltage vector which reduces said output current in such a way that the rate of reduction of said output current is minimized on the basis of the locations of said output current vector and counter electromotive force vector, and for enabling said voltage-type inverter to produce said selected voltage vector as the output, when the magnitude of said output current vector exceeds its limit value, said seventh means including: determination means for determining the location of said output current vector and for providing a rotation angle signal that specifies the amount of rotation necessary for the counter-electromotive force vector to rotate with regard to the determined location of said output current vector; counter-electromotive force vector determination force vector provided by said sixth means and said rotation angle signal provided by said determination means; and output pattern generating means for producing one of the predetermined switching patterns in response to said rotation angle signal and said determination output from said counter-electromotive force vector determination means.
References Cited (Backward Citations)
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