EP0073045A2
Expired / Lapsed
EP
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Method of controlling an induction motor by a PWM inverter
Assignee: Hitachi Ltd
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Filing: 1982-08-20
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Granted: —
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Expires: 2002-08-20
Abstract
Abstract For controlling the rotational speed of an induction motor (3), a pulse-width modulated inverter (2) is provided which converts direct current to alternating current, the converted current being fed to the motor (3). The output voltage and frequency of the inverter (2) is controlled in relation to the motor speed by changing the number of pulses in a half-cycle of the inverter output voltage in accordance with the DC supply voltage and/or with the motor current and/or in accordance with electrical fluctuations which are disturbances in a controlling system for the inverter output voltage.
Inventors
- 👤 Tokunosuke Tanamachi
- 👤 Hiroshi Narita
- 👤 Masahiko Ibamoto
- 👤 Shigetoshi Okamatsu
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 18:45
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/505; H02M7/515; H02M7/525; H02M7/527
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
134 words
A method of controlling an induction motor by an inverter (2) converting direct current to alternating current and feeding the converted current to the motor (3), and a pulse-width modulation controlling device (5) containing means for sequentially changing the number of pulses in a half cycle of the output voltage of the inverter (2)so as to control the output voltage and output frequency of the inverter in relation to the rotational speed of the motor (3), wherein the inverter (2) is pulse-width modulated by adjusting a reference value related to the rotational speed for changing said number of pulses in accordance with the DC supply voltage, and/or in accordance with the motor current and/or in accordance with electrical fluctuations which are disturbances for a controlling system for the output voltage of the inverter (2).
Claim 2
Independent Claim
134 words
A method of controlling an induction motor by an inverter (2) converting direct current to alternating current and feeding the converted current to the motor (3), and a pulse-width modulation controlling device (5) containing means for sequentially changing the number of pulses in a half cycle of the output voltage of the inverter (2)so as to control the output voltage and output frequency of the inverter in relation to the rotational speed of the motor (3), wherein the inverter (2) is pulse-width modulated by adjusting a reference value related to the rotational speed for changing said number of pulses in accordance with the DC supply voltage, and/or in accordance with the motor current and/or in accordance with electrical fluctuations which are disturbances for a controlling system for the output voltage of the inverter (2).
Claim 3
Dependent Claim
23 words
The method.of-claim 1, wherein the reference value related to said rotational speed is set for an operation frequency instruction for the inverter (2).
Claim 4
Dependent Claim
64 words
The method of claim 1 or 2, wherein the pulse-width modulation is made through the comparison of sine wave having the frequency of the operating frequency instruction for the inverter (2) with a triangular wave having a frequency which is an integral multiple of that of the sine wave, and wherein said pulse-number changing is performed by changing the frequency of said triangular wave.
Claim 5
Independent Claim
53 words
The method of any of claims 1 to 3, wherein a constant-current controlling system controlling the motor current at a fixed level in cooperation with said pulse-width modulation controlling device (5), and wherein said reference value is adjusted in accordance with a reference of the motor current given to said constant-current controlling system.
Claim 6
Independent Claim
138 words
A device for controlling an induction motor, including an inverter (2) converting direct current to alternating current and feeding the converted current to the motor (3), and a pulse-width modulation controlling device (5) containing means for sequentially changing the number of pulses in a half cycle of the output voltage of the inverter (2) so as to control the output voltage and output frequency of the inverter in relation to the rotational speed of the motor(3), wherein the inverter (2) is a pulse-width modulated-inverter including means (6...13) for adjusting a reference value relating to the rotational speed for changing said number of pulses in accordance with the DC supply voltage and/or in accordance with the motor current and/or in accordance with electrical fluctuations which are disturbances for a controlling system for the output voltage of the inverter (2).
Claim 7
Independent Claim
138 words
A device for controlling an induction motor, including an inverter (2) converting direct current to alternating current and feeding the converted current to the motor (3), and a pulse-width modulation controlling device (5) containing means for sequentially changing the number of pulses in a half cycle of the output voltage of the inverter (2) so as to control the output voltage and output frequency of the inverter in relation to the rotational speed of the motor(3), wherein the inverter (2) is a pulse-width modulated-inverter including means (6...13) for adjusting a reference value relating to the rotational speed for changing said number of pulses in accordance with the DC supply voltage and/or in accordance with the motor current and/or in accordance with electrical fluctuations which are disturbances for a controlling system for the output voltage of the inverter (2).
Claim 8
Dependent Claim
37 words
The device of claim 5, wherein said means for adjusting said reference value related to the rotational speed include means (6,10,11) for setting said reference value for an ope- . rating frequency instruction for the inverter (2).
Claim 9
Dependent Claim
72 words
The device of claim 5 or 6, wherein the pulse-width modulation controlling device (5) includes a comparison circuit (53) for comparing a sine wave having the frequency of the operating frequency instruction for the inverter (2) with a triangular wave having a frequency which is an integral multiple of that of the sine wave, and wherein said pulse-number changing means includes means (12, 51) for changing the frequency of said triangular wave.
Claim 10
Independent Claim
62 words
The device of any of claims 5 to 7, including a constant-current controlling system (7...9) for controlling the motor current at a fixed level in cooperation with said pulse-width modulation controlling device (5), and which is constituted in such a manner that said reference value is adjusted in accordance with a reference of the motor current given to said constant-current controlling system.
References Cited (Backward Citations)
No citation records indexed.
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