EP0013615A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Apparatus for controlling a.c. motor
Assignee: Hitachi Ltd
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Filing: 1980-01-07
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Granted: —
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Expires: 2000-01-07
Abstract
Abstract A first PWM inverter (1) for converting the acvoltage of an ac power source (AC) to a devoltage is connected through a dc circuit with a second PWM inverter (2) for driving an ac motor (3). A smoothing capacitor (15) is provided in the dc circuit. The firing angles of the first inverter (1) are so controlled that the voltage in the dc circuit may be kept at a predetermined value and the second inverter (2) is controlled in accordance with the speed instruction signalforthe acmotor(3), whereby the ac motor (3) can operate a regenerative operation without inducing higher harmonic components
Inventors
- 👤 Toshiaki Okuyama
- 👤 Hiroshi Nagase
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 01:02
CPC Classifications
H; H02; H02P; H02P23/00; H02P23/06
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
138 words
An apparatus for controlling an ac motor, comprising a first PWM inverter (1) for converting an ac voltage from an ac power source (AC) to a direct current; a second PWM inverter (2) for inverting the dc output of said first inverter (1) to an alternating current having a variable voltage and a variable frequency; an as motor (3) driven by said second inverter (2); a capacitor (15) connected between dc lines coupling said first inverter (1) to said second inverter ( 2 ) ; a first control means for controlling the firing angles of said first inverter (1) in such a manner that the voltage between said dc lines is kept at a predetermined value; and a second control means for controlling the firing angles of said second inverter (2) in accordance with a speed instruction signal.
Claim 2
Independent Claim
138 words
An apparatus for controlling an ac motor, comprising a first PWM inverter (1) for converting an ac voltage from an ac power source (AC) to a direct current; a second PWM inverter (2) for inverting the dc output of said first inverter (1) to an alternating current having a variable voltage and a variable frequency; an as motor (3) driven by said second inverter (2); a capacitor (15) connected between dc lines coupling said first inverter (1) to said second inverter ( 2 ) ; a first control means for controlling the firing angles of said first inverter (1) in such a manner that the voltage between said dc lines is kept at a predetermined value; and a second control means for controlling the firing angles of said second inverter (2) in accordance with a speed instruction signal.
Claim 3
Dependent Claim
33 words
An apparatus as claimed in Claim 1, wherein the firing angles of said first inverter (1) are so controlled that the voltage across said capacitor (15) may be kept at a predetermined value.
Claim 4
Dependent Claim
51 words
An apparatus as claimed in Claim 1, wherein the amplitude and the phase of the voltage at the input terminal of said first inverter (1) are so controlled that the phase difference between the voltage and the current of said ac power source (AC) may be set to a predetermined value.
Claim 5
Dependent Claim
28 words
An apparatus as claimed in Claim 1, wherein the ratio of the ac output voltage of said second inverter (2) to its frequency is controlled to be constant.
Claim 6
Independent Claim
153 words
An apparatus for controlling an ac motor, comprising a first PWM inverter (1) for converting an ac voltage from an ac power source (AC) to a direct current; a second PWM inverter (2) for inverting the dc output of said first inverter (1) to an alternating current having a variable voltage and a variable frequency; an ac motor (3) driven by said second inverter (2); a capacitor (15) connected between dc lines coupling said first inverter (1) to said second inverter (2); a first control means for controlling the firing angles of said first inverter (1) in such a manner that the voltage between said dc lines is kept at a predetermined value; a second control means for controlling the firing angles of said second inverter (2) in accordance with a speed instruction signal; and reactors (24) connected between said ac power source (AC) and the input terminals of said first inverter (1).
Claim 7
Independent Claim
153 words
An apparatus for controlling an ac motor, comprising a first PWM inverter (1) for converting an ac voltage from an ac power source (AC) to a direct current; a second PWM inverter (2) for inverting the dc output of said first inverter (1) to an alternating current having a variable voltage and a variable frequency; an ac motor (3) driven by said second inverter (2); a capacitor (15) connected between dc lines coupling said first inverter (1) to said second inverter (2); a first control means for controlling the firing angles of said first inverter (1) in such a manner that the voltage between said dc lines is kept at a predetermined value; a second control means for controlling the firing angles of said second inverter (2) in accordance with a speed instruction signal; and reactors (24) connected between said ac power source (AC) and the input terminals of said first inverter (1).
References Cited (Backward Citations)
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