Patent US3924173A successfully refreshed from Google Patents.
US3924173A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Commutation circuits in inverter circuits
Assignee: Individual
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Filing: 1974-06-17
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Granted: 1975-12-02
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Expires: 1994-06-17
Abstract
Abstract An inverter for supplying alternating current to a load from a direct current supply including a thyristor bridge for connecting the phase load or loads between the terminals of the direct current supply through respective inductors, or parts thereof. A flywheel diode bridge is also provided for returning energy induced by the load to the power supply. A commutation circuit, including a commutation capacitor is arranged for inducing thyristor turn-off voltage pulses in the inductors. The components are arranged, or means are provided, for reducing the voltage rating of the thyristors. Thus the connection of the commutation circuit to the inductors is such that the commutation capacitor voltage is applied across a different number of windings in various periods of the duration of the voltage pulse; the inductors may each have a second winding connected between an end of the flywheel diode bridge and the supply terminal opposite to that to which the first winding is connected; the commutation may be arranged never to be connected directly across the supply terminals, an auxiliary rectifier being provided for charging up and maintaining the voltage across the capacitor; the commutation capacitor may comprise two capacitors which are arranged in series between the supply terminals, and are selectively connectable to the inductors for generating the turn-off voltage pulse.
Inventors
- 👤 Sushil Kumar Goswami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:08
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/505; H02M7/515; H02M7/5152
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
332 words
An inverter for supplying alternating current to a load from a direct current supply, including a controlled rectifier bridge which comprises a respective pair of first and second controlled rectifiers for connecting each A.C. supply terminal of the load to the positive and negative terminals of the direct current supply, the first controlled rectifier of each pair being connected to the positive supply terminal through at least part of a first inductor, and the second controlled rectifier of each pair being connected to the negative supply terminal through at least part of a second inductor, a flywheel diode bridge comprising a respective pair of flywheel diodes also for connecting each A.C. supply terminal of the load to the direct curRent supply terminals and a commutation circuit including a selectively dischargeable commutation capacitor for causing current to flow in one or other of said inductors and thereby to reverse bias so as to turn off a conducting one of the rectifiers connected thereto, wherein each inductor is provided with a second winding, which is magnetically coupled with the first winding of the inductor, the second winding of the first inductor being connected between the negative direct current supply terminal and the respective end of the flywheel diode bridge, and the second winding of the second inductor being connected between the positive direct current supply terminal and the respective end of the flywheel diode bridge, the polarity of the first and second windings of each inductor being such that when the first winding of the second inductor makes the thyristor bridge end connected thereto more positive than the negative supply potential, the second winding thereof makes the flywheel diode bridge end connected thereto less positive than the positive supply potential, and such that when the first winding of the first inductor makes the thyristor bridge end connected thereto less positive than the positive supply potential the second winding thereof makes the flywheel diode bridge end connected thereto more positive than the negative supply potential.
Claim 2
Dependent Claim
332 words
An inverter for supplying alternating current to a load from a direct current supply, including a controlled rectifier bridge which comprises a respective pair of first and second controlled rectifiers for connecting each A.C. supply terminal of the load to the positive and negative terminals of the direct current supply, the first controlled rectifier of each pair being connected to the positive supply terminal through at least part of a first inductor, and the second controlled rectifier of each pair being connected to the negative supply terminal through at least part of a second inductor, a flywheel diode bridge comprising a respective pair of flywheel diodes also for connecting each A.C. supply terminal of the load to the direct curRent supply terminals and a commutation circuit including a selectively dischargeable commutation capacitor for causing current to flow in one or other of said inductors and thereby to reverse bias so as to turn off a conducting one of the rectifiers connected thereto, wherein each inductor is provided with a second winding, which is magnetically coupled with the first winding of the inductor, the second winding of the first inductor being connected between the negative direct current supply terminal and the respective end of the flywheel diode bridge, and the second winding of the second inductor being connected between the positive direct current supply terminal and the respective end of the flywheel diode bridge, the polarity of the first and second windings of each inductor being such that when the first winding of the second inductor makes the thyristor bridge end connected thereto more positive than the negative supply potential, the second winding thereof makes the flywheel diode bridge end connected thereto less positive than the positive supply potential, and such that when the first winding of the first inductor makes the thyristor bridge end connected thereto less positive than the positive supply potential the second winding thereof makes the flywheel diode bridge end connected thereto more positive than the negative supply potential.
Claim 3
Dependent Claim
119 words
An inverter according to claim 1 wherein for each inductor, the number of turns of the second winding connected between the respective direct current supply terminal and the respective dc end of the flywheel diode bridge is made smaller than the number of turns of the first winding connected between the respective direct current supply terminal and the respective point of connection to the inverter thyristor bridge, so as to ensure that reverse biasing of the inverter-thyristor to be turned off is achieved at a commutation capacitor voltage lower than that which enables the combination of the second windings and the flywheel diode bridge to extract excess energy from the commutation capacitor to deliver it to the dc supply.
Claim 4
Dependent Claim
74 words
An inverter according according to claim 1 wherein each of said first or second windings has three points connected into said commutation circuit, namely an intermediate point and a further point on either side thereof, the intermediate point and one of said further points each being connected via a respective single anode rectifier into a respective loop containing the commutation capacitor, the loop completing itself through the other said further point on the inductor.
Claim 5
Dependent Claim
247 words
An inverter for supplying alternating current to a load from a direct current supply, comprising a respective pair of first and second controlled rectifiers for connecting each A.C. supply terminal of the load to the positive and negative terminals of the direct current supply, the first controlled rectifier of each pair being connected to the positive supply terminal through at least part of a first inductor, and the second controlled rectifier of each pair being connected to the negative supply terminal through at least part of a second inductor, a flywheel diode bridge comprising a respective pair of flywheel diodes also for connecting each A.C. supply terminal of the load to the direct current supply terminals, and a commutation circuit including a selectively dischargeable commutation capacitor for causing current to flow in one or other of said inductors, each of which, or a part thereof, is connected in a respective commutation loop in which discharge current from said commutation capacitor will flow, and thereby to reverse bias so as to turn off a conducting one of the rectifiers connected thereto, wherein said commutation capacitor is arranged so that it is never connected across the direct current supply and therefore never draws charging current therefrom, and wherein means are therefore provided for charging and for increasing or decreasing the voltage of said commutation capacitor, said means comprising an auxiLiary direct current power supply connected in series in a uni-directional current path of one of the said commutation loops.
Claim 6
Dependent Claim
247 words
An inverter for supplying alternating current to a load from a direct current supply, comprising a respective pair of first and second controlled rectifiers for connecting each A.C. supply terminal of the load to the positive and negative terminals of the direct current supply, the first controlled rectifier of each pair being connected to the positive supply terminal through at least part of a first inductor, and the second controlled rectifier of each pair being connected to the negative supply terminal through at least part of a second inductor, a flywheel diode bridge comprising a respective pair of flywheel diodes also for connecting each A.C. supply terminal of the load to the direct current supply terminals, and a commutation circuit including a selectively dischargeable commutation capacitor for causing current to flow in one or other of said inductors, each of which, or a part thereof, is connected in a respective commutation loop in which discharge current from said commutation capacitor will flow, and thereby to reverse bias so as to turn off a conducting one of the rectifiers connected thereto, wherein said commutation capacitor is arranged so that it is never connected across the direct current supply and therefore never draws charging current therefrom, and wherein means are therefore provided for charging and for increasing or decreasing the voltage of said commutation capacitor, said means comprising an auxiLiary direct current power supply connected in series in a uni-directional current path of one of the said commutation loops.
Claim 7
Dependent Claim
66 words
An inverter according to claim 4 wherein said auxiliary direct current power supply comprises an auxiliary controlled rectifier circuit arranged for connection to an alternating current supply and for the production of a rectified voltage across an auxiliary capacitor connected in said commutation loop, the auxiliary rectifier circuit current carrying capability being in the same direction as that of the uni-directional current in said commutation loop.
Claim 8
Dependent Claim
16 words
An inverter according to claim 5 wherein the said auxiliary rectifier circuit is a controlled circuit.
Claim 9
Dependent Claim
16 words
An inverter according to claim 6 wherein the said auxiliary rectifier circuit is a half-controlled circuit.
Claim 10
Dependent Claim
36 words
An inverter according to claim 5 wherein a plurality of said auxiliary rectifier circuits are provided, each being located at one of a plurality of points in one or both of the commutation capacitor circuit loops.
Claim 11
Dependent Claim
31 words
An inverter circuit according to claim 8 wherein a plurality of the said auxiliary rectifier circuits are combined by employing a common auxiliary alternating current supply transformer with a common primary.
Claim 12
Dependent Claim
99 words
An inverter according to claim 9, wherein said commutation loops have a common branch in which is located said commutation capacitor, wherein each loop contains a said auxiliary rectifier circuit and auxiliary capacitor, located at point where the two commutation loops merge into said common branch, said auxiliary capacitors being connected in series, with their point of connection connected via a part of said common branch to one electrode of the commutation capacitor, and wherein said auxiliary rectifier circuits are replaced by a single auxiliary rectifier circuit arranged to produce a rectified voltage across said series connected auxiliary capacitors.
Claim 13
Dependent Claim
15 words
An inverter according to claim 6 wherein the said auxiliary rectifier circuit is fully controlled.
Claim 14
Dependent Claim
271 words
An inverter for supply alternating current to a load from a direct current supply, comprising a respective pair of first and second controlled rectifiers for connecting each A.C. supply terminal of the load to the positive and negative terminals of the direct current supply, the first controlled rectifier of each pair being connected to the positive supply terminal through at least part of a first inductor, and the second controlled rectifier of each pair being connected to the negative supply terminal through at least part of a second inductor, a respective pair of flywheel diodes also for connecting each A.C. supply terminal of the load to the direct current supply terminals and a commutation circuit including a selectively dischargeable commutation capacitor for causing current to flow in one or other of said inductors and thereby to reverse bias so as to turn off a conducting one of the rectifiers connected thereto, each said indicator comprising a winding having three points connected in said commutation circuit, namely an intermediate point and a further point on either side thereof wherein there is provided in respect of each inductor a pair of single-anode rectifiers coupled to connect either said intermediate point or said first further point into a respective loop containing the commutation capacitor, the loop completing itself through the other said further point on the inductor, whereby said loop may contain either the part of the inductor between the other further point and the intermediate point or the part between the said other further point and the first further point depending upon which of said respective single-anode rectifiers is in a conductive state.
Claim 15
Dependent Claim
271 words
An inverter for supply alternating current to a load from a direct current supply, comprising a respective pair of first and second controlled rectifiers for connecting each A.C. supply terminal of the load to the positive and negative terminals of the direct current supply, the first controlled rectifier of each pair being connected to the positive supply terminal through at least part of a first inductor, and the second controlled rectifier of each pair being connected to the negative supply terminal through at least part of a second inductor, a respective pair of flywheel diodes also for connecting each A.C. supply terminal of the load to the direct current supply terminals and a commutation circuit including a selectively dischargeable commutation capacitor for causing current to flow in one or other of said inductors and thereby to reverse bias so as to turn off a conducting one of the rectifiers connected thereto, each said indicator comprising a winding having three points connected in said commutation circuit, namely an intermediate point and a further point on either side thereof wherein there is provided in respect of each inductor a pair of single-anode rectifiers coupled to connect either said intermediate point or said first further point into a respective loop containing the commutation capacitor, the loop completing itself through the other said further point on the inductor, whereby said loop may contain either the part of the inductor between the other further point and the intermediate point or the part between the said other further point and the first further point depending upon which of said respective single-anode rectifiers is in a conductive state.
Claim 16
Dependent Claim
156 words
An inverter according to claim 12, wherein in respect of each inductor winding, a first one of said single-anode rectifiers is series connected within that winding between said first further point and the next connection point on the winding, which may be the said intermediate point or a point Connected to the controlled rectifiers of the inverter or to a D.C. supply terminal, wherein the other of said single-anode rectifiers connects said intermediate point to a common connection on said commutation loop, wherein said first further point is connected to said common connection, so that when only said first one of said single-anode rectifiers conducts, the part of the inductor between said first further point and said other further point is connected into said commutation loop, and when only said other of said single-anode rectifiers conducts, the part of the inductor between said intermediate point and said other further point is connected into said commutation loop.
Claim 17
Dependent Claim
76 words
An inverter according to claim 12 wherein said intermediate and first further point on the first inductor are connected to the cathodes of the respective single anode rectifiers, the anodes of which are commoned together and said intermediate and first further point on the second inductor are connected to the anodes of the respective single anode rectifiers, the cathodes of which are commoned together, said commoned anodes and commoned cathodes being connected in the respective loops.
Claim 18
Dependent Claim
76 words
An inverter according to claim 12 wherein said intermediate and first further point on the first inductor are connected to the anodes of the respective single anode rectifiers, the cathodes of which are commoned together, and said intermediate and first further point on the second inductor are connected to the cathodes of the respective single anode rectifiers, the anodes of which are commoned together, said commoned cathodes and commoned anodes being connected in the respective loops.
Claim 19
Dependent Claim
59 words
An inverter according to claim 15, wherein said single-anode rectifiers are non-controlled and are connected so as to point in the forward direction of the direct current supply and wherein, in respect of each inductor, a controlled single anode rectifier is series connected, in the respective commutation loop, to the respective commoned electrodes of the said non-controlled, single-anode rectifiers.
Claim 20
Dependent Claim
66 words
An inverter according to claim 12, wherein said commutation capacitor is arranged so as never to be connected across the direct current supply and wherein means are therefore provided for charging and for increasing or decreasing the voltage on said commutation capacitor, said means comprising an auxiliary direct current power supply connected in series in a unidirectional current part of one of the said commutation loops.
Claim 21
Dependent Claim
65 words
An inverter according to claim 17 wherein said auxiliary direct current power supply comprises an auxiliary rectifier circuit arranged for connection to an alternating current supply and for the production of a rectified voltage across an auxiliary capacitor connected in said commutation loop, the auxiliary rectifier circuit current carrying capability being in the same direction as that of the uni-directional current in said commutation loop.
Claim 22
Dependent Claim
52 words
An inverter according to claim 18 wherein said single anode rectifiers are connected so as to point in a direction opposing the direct current supply, and are both of the uncontrolled type, the said commoned electrodes being connected directly, or via an auxiliary rectifier circuit, to one terminal of the commutation capacitor.
Claim 23
Dependent Claim
28 words
An inverter according to claim 19 wherein a single-anode rectifier is series-connected, in the commutation loop, between the other terminal of commutation capacitor and the other further point.
Claim 24
Dependent Claim
25 words
An inverter according to claim 12, wherein said controlled rectifiers form a 3-phase bridge, and wherein said flywheel diodes form a 3-phase flywheel diode bridge.
Claim 25
Dependent Claim
12 words
An inverter according to claim 12 wherein said controlled rectifiers are thyristors.
Claim 26
Dependent Claim
192 words
An inverter for supplying alternating current to a load from a direct current connected comprising a respective pair of first and second controlled rectifiers for connecting each A.C. supply terminal of the load to the positive aNd negative terminals of the direct current supply, the first controlled rectifier of each pair being connected to the positive supply terminal through at least part of a first inductor, and the second controlled rectifier of each pair being connected to the negative supply terminal through at least part of a second inductor, a flywheel diode bridge comprising a respective pair of flywheel diodes also for connecting each A.C. supply terminal of the load to the direct current supply terminals, and a commutation circuit including a selectively dischargeable commutation capacitor means for causing current to flow in one or other of said inductors and thereby to reverse bias so as to turn off a conducting one of the rectifiers connected thereto wherein the commutation capacitor means comprises two capacitors which are connectd in series across the main dc supply and are selectively connectable to the inductors to develop controlled rectifier turn-off voltage pulses across the inductors.
Claim 27
Dependent Claim
192 words
An inverter for supplying alternating current to a load from a direct current connected comprising a respective pair of first and second controlled rectifiers for connecting each A.C. supply terminal of the load to the positive aNd negative terminals of the direct current supply, the first controlled rectifier of each pair being connected to the positive supply terminal through at least part of a first inductor, and the second controlled rectifier of each pair being connected to the negative supply terminal through at least part of a second inductor, a flywheel diode bridge comprising a respective pair of flywheel diodes also for connecting each A.C. supply terminal of the load to the direct current supply terminals, and a commutation circuit including a selectively dischargeable commutation capacitor means for causing current to flow in one or other of said inductors and thereby to reverse bias so as to turn off a conducting one of the rectifiers connected thereto wherein the commutation capacitor means comprises two capacitors which are connectd in series across the main dc supply and are selectively connectable to the inductors to develop controlled rectifier turn-off voltage pulses across the inductors.
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) | 1978-12-01 | 1979-06-02 | 1979-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-01 | 1983-06-02 | 1983-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-01 | 1987-06-02 | 1987-12-02 | $7700.00 | Window Closed / Lapsed |