US4405977A
Expired / Lapsed
US
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Commutation circuits for thyristor inverters
Assignee: Concordia University
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Filing: 1981-08-26
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Granted: 1983-09-20
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Expires: 2001-08-26
Abstract
Abstract The commutation circuit for commutating a conducting thyristor includes an inductance, a capacitance and a commutation thyristor all connected in series with the conducting thyristor and the dc source, the commutation thyristor initiates the commutation when triggered. The circuit further includes a first diode connected in reverse polarity across the commutation thyristor and a second diode connected in reverse polarity across the commutation thyristor-capacitance series circuit. The voltage across the capacitance is zero when each commutation cycle is initiated, and also when each commutation cycle ends.
Inventors
- 👤 Pradeep M. Bhagwat
- 👤 Victor R. Stefanovic
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:15
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/505; H02M7/515; H02M7/523; H02M7/5233; H02M7/5236
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
66 words
In a thyristor circuit for applying a dc voltage through a thyristor to a load, a commutation circuit for the thyristor comprising: inductance means, normally discharged capacitance means and a commutation thyristor connected in series with said thyristor; a first diode connected in reverse polarity across the commutation thyristor; and a second diode connected in reverse polarity across the series connected capacitance means and commutation thyristor.
Claim 2
Dependent Claim
66 words
In a thyristor circuit for applying a dc voltage through a thyristor to a load, a commutation circuit for the thyristor comprising: inductance means, normally discharged capacitance means and a commutation thyristor connected in series with said thyristor; a first diode connected in reverse polarity across the commutation thyristor; and a second diode connected in reverse polarity across the series connected capacitance means and commutation thyristor.
Claim 3
Dependent Claim
20 words
A commutation circuit as claimed in claim 1 which includes a third diode connected in reverse polarity across said thyristor.
Claim 4
Dependent Claim
117 words
In an inverter circuit having at least a pair of first and second thyristors connected in series across a dc source with a first juncture between the first and second thyristors for connection to a load, a thyristor commutation circuit comprising: a pair of series connected first and second commutation thyristors connected in parallel with the first and second thyristors; a diode connected in reverse polarity across each of the first and second thyristors and the first and second commutation thyristors; normally discharged first capacitance means connected to a second juncture between the first and second commutation thyristors and the first juncture; and first inductance means series connected between the dc source and the pairs of thyristors.
Claim 5
Dependent Claim
117 words
In an inverter circuit having at least a pair of first and second thyristors connected in series across a dc source with a first juncture between the first and second thyristors for connection to a load, a thyristor commutation circuit comprising: a pair of series connected first and second commutation thyristors connected in parallel with the first and second thyristors; a diode connected in reverse polarity across each of the first and second thyristors and the first and second commutation thyristors; normally discharged first capacitance means connected to a second juncture between the first and second commutation thyristors and the first juncture; and first inductance means series connected between the dc source and the pairs of thyristors.
Claim 6
Dependent Claim
27 words
A commutation circuit as claimed in claim 3 which further includes an ac switch and resistance means connected across the capacitance means for discharging the capacitance means.
Claim 7
Dependent Claim
19 words
A commutation circuit as claimed in claim 3 which further includes filter capacitance means connected across the dc source.
Claim 8
Dependent Claim
52 words
A commutation circuit as claimed in claim 5 which further includes: a second inductance means connected between the dc source and the first inductance means; a diode connected in reverse polarity across the second inductance means; and second capacitance means connected in series with the second inductance means across the dc source.
Claim 9
Dependent Claim
30 words
A commutation circuit as claimed in claim 4, 5, or 6 wherein the first inductance means is a single inductor connected between the dc source and the pairs of thyristors.
Claim 10
Dependent Claim
47 words
A commutation circuit as claimed in claim 4, 5, or 6 wherein the first inductance means includes a first inductor connected between the dc source and the pairs of thyristors, and a second inductor connected in series with the capacitance means between the first and second junctures.
Claim 11
Dependent Claim
27 words
A commutation circuit as claimed in claim 4, 5, or 6 wherein the first inductance means consists of an inductor connected directly to each of the thyristors.
Claim 12
Dependent Claim
151 words
In an inverter circuit having at least a pair of inverter thyristors connected in series across a variable dc source with a first juncture between the inverter thyristors for connection to a load, a thyristor commutation circuit comprising: a series circuit having a first blocking diode, a fixed dc source and a second blocking diode connected across the series connected inverter thyristors; a pair of series connected commutation thyristors and a pair of series connected auxiliary thyristors connected in parallel across the fixed dc source, the juncture between the auxiliary thyristors being connected to the first juncture; a diode connected in reverse polarity across each of the pair of inverter thyristors and the pair of commutation thyristors; first capacitance means connected to a juncture between the commutation thyristors and the first juncture; and first inductance means series connected between the fixed dc source and the pairs of commutation and auxiliary thyristors.
Claim 13
Dependent Claim
151 words
In an inverter circuit having at least a pair of inverter thyristors connected in series across a variable dc source with a first juncture between the inverter thyristors for connection to a load, a thyristor commutation circuit comprising: a series circuit having a first blocking diode, a fixed dc source and a second blocking diode connected across the series connected inverter thyristors; a pair of series connected commutation thyristors and a pair of series connected auxiliary thyristors connected in parallel across the fixed dc source, the juncture between the auxiliary thyristors being connected to the first juncture; a diode connected in reverse polarity across each of the pair of inverter thyristors and the pair of commutation thyristors; first capacitance means connected to a juncture between the commutation thyristors and the first juncture; and first inductance means series connected between the fixed dc source and the pairs of commutation and auxiliary thyristors.
Claim 14
Dependent Claim
27 words
A commutation circuit as claimed in claim 10 which further includes an ac switch and resistance means connected across the capacitance means for discharging the capacitance means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-09-19 | 1987-03-21 | 1987-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-19 | 1991-03-21 | 1991-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-19 | 1995-03-21 | 1995-09-20 | $7700.00 | Window Closed / Lapsed |