Patent US3493877A successfully refreshed from Google Patents.
US4623830A
Expired / Lapsed
US
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Alternating-current machine drive
Assignee: BBC Brown Boveri AG Switzerland
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Filing: 1984-07-10
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Granted: 1986-11-18
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Expires: 2004-07-10
Abstract
Abstract In this context, a frequency converter generates a multiphase alternating current of variable frequency which current feeds an alternating-current machine via alternating-current lines into which for each alternating current phase line one commutating choke is integrated for limiting the change of current with respect to time di/dt. Since the efficiency of a synchronous motor is best when fed with a sinusoidal alternating current, a frequency-variable filter is provided as a bypass circuit to the synchronous motor which makes the alternating current sinusoidal within a predeterminable frequency range. The frequency of the alternating current is measured with a frequency meter and monitored for exceeding a limit in a frequency limit detector. The filter can be tuned step-by-step by means of switching signals to different frequencies by changing the inductance or capacitance of series-tuned circuits step-by-step. Undesirable harmonic frequencies can thus be attenuated with-in a relatively large frequency range.
Inventors
- 👤 Franz Peneder
- 👤 Vojen Suchanek
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:11
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/12; H02P; H02P25/00; H02P25/02; H02P25/022; H02P25/024; Y; Y02; Y02P; Y02P80/00; Y02P80/10
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
226 words
An alternating-current machine drive, comprising: a multiphase alternating-current machine; a frequency converter generating an alternating current with a predeterminable variable frequency; alternating current lines connecting said machine to said converter; a frequency-variable filter having a resonance frequency and connected in parallel with said machine for filtering out at least one harmonic of said alternating current; means for varying the resonance frequency of said filter as a function of the variable frequency of the current generated by said frequency converter; said filter including for each phase of said alternating current and for each of said harmonics to be filtered out one series-tuned circuit tuned to the respective harmonic; each of said series-tuned circuits having a filter capacitor connected in series with a filter choke; said filter choke including a frequency-dependent resistive impedance; each of said series-tuned circuits being connected at the input of said alternating-current lines; and wherein: series-tuned filters which are connected at the input to the same one of said alternating-current lines are connected at the output together and to one end of an add-on choke; said add-on chokes being connected together at the other end; and series-tuned filters which are connected at the input to different ones of said alternating-current lines are connected at the output to each other by way of alternating-current switches which produce a short circuit when said switches are actuated.
Claim 2
Dependent Claim
226 words
An alternating-current machine drive, comprising: a multiphase alternating-current machine; a frequency converter generating an alternating current with a predeterminable variable frequency; alternating current lines connecting said machine to said converter; a frequency-variable filter having a resonance frequency and connected in parallel with said machine for filtering out at least one harmonic of said alternating current; means for varying the resonance frequency of said filter as a function of the variable frequency of the current generated by said frequency converter; said filter including for each phase of said alternating current and for each of said harmonics to be filtered out one series-tuned circuit tuned to the respective harmonic; each of said series-tuned circuits having a filter capacitor connected in series with a filter choke; said filter choke including a frequency-dependent resistive impedance; each of said series-tuned circuits being connected at the input of said alternating-current lines; and wherein: series-tuned filters which are connected at the input to the same one of said alternating-current lines are connected at the output together and to one end of an add-on choke; said add-on chokes being connected together at the other end; and series-tuned filters which are connected at the input to different ones of said alternating-current lines are connected at the output to each other by way of alternating-current switches which produce a short circuit when said switches are actuated.
Claim 3
Dependent Claim
179 words
An alternating-current machine drive, comprising: a multiphase alternating-current machine; a frequency converter generating an alternating current with a predeterminable variable frequency; alternating current lines connecting said machine to said converter; a frequency-variable filter having a resonance frequency and connected in parallel with said machine for filtering out at least one harmonic of said alternating current; means for varying the resonance frequency of said filter as a function of the variable frequency of the current generated by said frequency converter; said filter including for each phase of said alternating current and for each of said harmonics to be filtered out one series-tuned circuit tuned to the respective harmonic; each of said series-tuned circuits having a filter capacitor connected in series with a filter choke; said filter choke including a frequency-dependent resistive impedance; each of said series-tuned circuits being connected at the input to said alternating-current lines; and wherein: said filter choke includes a main filter choke in series with at least two further add-on filter chokes which are connected in parallel with each other by way of one current rectifier.
Claim 4
Dependent Claim
179 words
An alternating-current machine drive, comprising: a multiphase alternating-current machine; a frequency converter generating an alternating current with a predeterminable variable frequency; alternating current lines connecting said machine to said converter; a frequency-variable filter having a resonance frequency and connected in parallel with said machine for filtering out at least one harmonic of said alternating current; means for varying the resonance frequency of said filter as a function of the variable frequency of the current generated by said frequency converter; said filter including for each phase of said alternating current and for each of said harmonics to be filtered out one series-tuned circuit tuned to the respective harmonic; each of said series-tuned circuits having a filter capacitor connected in series with a filter choke; said filter choke including a frequency-dependent resistive impedance; each of said series-tuned circuits being connected at the input to said alternating-current lines; and wherein: said filter choke includes a main filter choke in series with at least two further add-on filter chokes which are connected in parallel with each other by way of one current rectifier.
Claim 5
Dependent Claim
20 words
An alternating-current machine drive according to claim 2, wherein said current rectifier is an alternating-current switch with anti-parallel connected thyristors.
Claim 6
Dependent Claim
228 words
An alternating-current machine drive, comprising: a multiphase alternating-current machine; a frequency converter generating an alternating current with a predeterminable variable frequency; alternating current lines connecting said machine to said converter; a frequency-variable filter having a resonance frequency and connected in parallel with said machine for filtering out at least one harmonic of said alternating current; means for varying the resonance frequency of said filter as a function of the variable frequency of the current generated by said frequency converter; said filter including for each phase of said alternating current and for each of said harmonics to be filtered out one series-tuned circuit tuned to the respective harmonic; each of said series-tuned circuits having a filter capacitor connected in series with a filter choke; said filter choke including a frequency-dependent resistive impedance; each of said series-tuned circuits being connected at the input to said alternating-current lines; said filter choke including a main filter choke in series with at least two further add-on filter chokes which are connected in parallel with each other by way of one current rectifier; wherein: said add-on filter chokes are each provided with a ferromagnetic core; said current rectifiers are connected in series with each of said add-on filter chokes; and said current rectifiers conduct in the same direction such that only one half cycle of said alternating current passes through each add-on filter choke.
Claim 7
Dependent Claim
228 words
An alternating-current machine drive, comprising: a multiphase alternating-current machine; a frequency converter generating an alternating current with a predeterminable variable frequency; alternating current lines connecting said machine to said converter; a frequency-variable filter having a resonance frequency and connected in parallel with said machine for filtering out at least one harmonic of said alternating current; means for varying the resonance frequency of said filter as a function of the variable frequency of the current generated by said frequency converter; said filter including for each phase of said alternating current and for each of said harmonics to be filtered out one series-tuned circuit tuned to the respective harmonic; each of said series-tuned circuits having a filter capacitor connected in series with a filter choke; said filter choke including a frequency-dependent resistive impedance; each of said series-tuned circuits being connected at the input to said alternating-current lines; said filter choke including a main filter choke in series with at least two further add-on filter chokes which are connected in parallel with each other by way of one current rectifier; wherein: said add-on filter chokes are each provided with a ferromagnetic core; said current rectifiers are connected in series with each of said add-on filter chokes; and said current rectifiers conduct in the same direction such that only one half cycle of said alternating current passes through each add-on filter choke.
Claim 8
Dependent Claim
37 words
An alternating-current machine drive according to claim 4, wherein the inductance of the said add-on chokes are not saturated for frequencies below the frequency of the harmonic to be filtered out and are saturated above said frequency.
Claim 9
Dependent Claim
24 words
An alternating-current machine according to claim 4, wherein said filter choke has several taps connected to the output by way of a stepping switch.
Claim 10
Dependent Claim
39 words
An alternating-current machine drive according to claim 4, wherein one series-tuned circuit for each of the harmonics to be filtered out is connected between one of the alternating current lines and each of the other of said alternating-current lines.
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