US5365422A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pulse-width modulated circuit for applying current to a load
Assignee: Hitachi Healthcare Manufacturing Ltd
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Filing: 1993-06-01
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Granted: 1994-11-15
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Expires: 2013-06-01
Abstract
Abstract A pulse-width modulated (PWM) circuit alternately applies voltage from a power supply across a load, and alternately establishes one or more non-powered, closed paths for freewheeling current. The circuit includes pairs of switches connected to the load and also connected to the power supply. PWM signals derived from a command signal drive the switches in such a manner as to create the freewheeling current paths in a desired pattern and sequence. The circuit effectively reduces ripple current in the load while also substantially reducing the amount of current flowing through the power supply filter capacitor. Thus, the size and rating of the power supply can be reduced. One can use the invention to drive a load in a multiple-phase environment, and also in the context of a three-phase trapezoidal drive.
Inventors
- 👤 Eric C. Close
- 👤 Jerry K. Goff
- 👤 Donald A. Yost
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:52
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; H02M7/5387; H02M7/53871; H02M7/53878
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
162 words
A circuit for applying current to a load, the circuit comprising: a) a power supply, b) four switches, all of the switches having at least two terminals, one terminal of each switch being connected to the power supply and the other terminal being connected to the load, wherein the switches comprise means for defining paths for current from the power supply, to the load, and back to the power supply, and wherein the switches also comprise means for defining at least one closed path for current flow, wherein said closed path excludes the power supply, and c) means for generating pulse-width modulated signals, wherein said signals control the switches, and wherein the signals are arranged such that they alternate between providing a path for current from the power supply through the load and back to the power supply, and establishing said closed path which excludes the power supply, wherein there are at least two independent pulse-width modulated signals for controlling the switches.
Claim 2
Dependent Claim
162 words
A circuit for applying current to a load, the circuit comprising: a) a power supply, b) four switches, all of the switches having at least two terminals, one terminal of each switch being connected to the power supply and the other terminal being connected to the load, wherein the switches comprise means for defining paths for current from the power supply, to the load, and back to the power supply, and wherein the switches also comprise means for defining at least one closed path for current flow, wherein said closed path excludes the power supply, and c) means for generating pulse-width modulated signals, wherein said signals control the switches, and wherein the signals are arranged such that they alternate between providing a path for current from the power supply through the load and back to the power supply, and establishing said closed path which excludes the power supply, wherein there are at least two independent pulse-width modulated signals for controlling the switches.
Claim 3
Dependent Claim
132 words
A circuit for applying current to a load, the circuit comprising: a) a power supply, b) a plurality of switches, all of the switches being connected to the power supply and to the load, wherein the switches comprise means for defining paths for current from the power supply, to the load, and back to the power supply, and wherein the switches also comprise means for defining at least two closed paths for current flow, wherein said closed paths exclude the power supply, and c) means for opening and closing the switches, wherein the opening and closing means comprises means for establishing at least one current path from the power supply through the load and back to the power supply, and for establishing either of said closed paths which exclude the power supply.
Claim 4
Dependent Claim
132 words
A circuit for applying current to a load, the circuit comprising: a) a power supply, b) a plurality of switches, all of the switches being connected to the power supply and to the load, wherein the switches comprise means for defining paths for current from the power supply, to the load, and back to the power supply, and wherein the switches also comprise means for defining at least two closed paths for current flow, wherein said closed paths exclude the power supply, and c) means for opening and closing the switches, wherein the opening and closing means comprises means for establishing at least one current path from the power supply through the load and back to the power supply, and for establishing either of said closed paths which exclude the power supply.
Claim 5
Dependent Claim
34 words
The circuit of claim 2, wherein the opening and closing means comprises means for generating pulse-width modulated signals, wherein the pulse-width modulated signals are connected to the switches so as to control the switches.
Claim 6
Dependent Claim
19 words
The circuit of claim 3, wherein there are at least two independent pulse-width modulated signals for controlling the switches.
Claim 7
Dependent Claim
134 words
A circuit for applying current to a load, the circuit comprising: a) a power supply, b) a plurality of switches, all of the switches being connected to the power supply and to the load, wherein the switches comprise means for defining paths for current from the power supply, to the load, and back to the power supply, and wherein the switches also comprise means for defining at least one closed path for current flow, wherein said closed path excludes the power supply, and c) at least two independent means for opening and closing the switches, wherein the opening and closing means comprise means for establishing at least one current path from the power supply through the load and back to the power supply, and for establishing said closed path which excludes the power supply.
Claim 8
Dependent Claim
134 words
A circuit for applying current to a load, the circuit comprising: a) a power supply, b) a plurality of switches, all of the switches being connected to the power supply and to the load, wherein the switches comprise means for defining paths for current from the power supply, to the load, and back to the power supply, and wherein the switches also comprise means for defining at least one closed path for current flow, wherein said closed path excludes the power supply, and c) at least two independent means for opening and closing the switches, wherein the opening and closing means comprise means for establishing at least one current path from the power supply through the load and back to the power supply, and for establishing said closed path which excludes the power supply.
Claim 9
Dependent Claim
125 words
A pulse-width modulated circuit for varying the flow of current to a load, the circuit comprising: a) switching means for connecting the load to a source of power such that current flows through the load, b) the switching means also including means for connecting the load to at least one closed circuit which does not include the power source, wherein current flowing through the load can continue to flow through said closed circuit, and c) at least two independent pulse means for controlling the switching means such that, for at least a portion of an operating cycle, the load is connected to the power source, and for another portion of the operating cycle the load is connected to at least one of said closed circuits.
Claim 10
Dependent Claim
125 words
A pulse-width modulated circuit for varying the flow of current to a load, the circuit comprising: a) switching means for connecting the load to a source of power such that current flows through the load, b) the switching means also including means for connecting the load to at least one closed circuit which does not include the power source, wherein current flowing through the load can continue to flow through said closed circuit, and c) at least two independent pulse means for controlling the switching means such that, for at least a portion of an operating cycle, the load is connected to the power source, and for another portion of the operating cycle the load is connected to at least one of said closed circuits.
Claim 11
Dependent Claim
53 words
The circuit of claim 6, wherein said at least one closed circuit comprises closed circuits, and wherein the pulse means comprises means for connecting the load, in sequence, to the power source, to one of said closed circuits, to the power source again, to the other of said closed circuits, and so forth.
Claim 12
Independent Claim
83 words
A method of applying current to a load, the method comprising the steps of: a) configuring a plurality of switches connected between the load and a power supply so that current flows from the power supply to the load and back to the power supply, b) reconfiguring the switches such that current flows through the load in a closed loop which excludes the power supply, and c) alternately repeating steps (a) and (b), wherein step (b) is performed alternately with different closed loops.
Claim 13
Independent Claim
83 words
A method of applying current to a load, the method comprising the steps of: a) configuring a plurality of switches connected between the load and a power supply so that current flows from the power supply to the load and back to the power supply, b) reconfiguring the switches such that current flows through the load in a closed loop which excludes the power supply, and c) alternately repeating steps (a) and (b), wherein step (b) is performed alternately with different closed loops.
Claim 14
Dependent Claim
48 words
The method of claim 7, wherein each of the switches has an open state and a closed state, and wherein the configuring and reconfiguring steps comprise the steps of converting an error signal into a set of pulse trains and using said pulse trains to control the switches.
Claim 15
Dependent Claim
14 words
The method of claim 9, wherein there are at least two independent pulse trains.
Claim 16
Independent Claim
101 words
A method of applying current to a load, the method comprising the steps of: a) configuring a plurality of switches connected between the load and a power supply so that current flows from the power supply to the load and back to the power supply, b) reconfiguring the switches such that current flows through the load in a closed loop which excludes the power supply, and c) repeating steps (a) and (b) such that step (b) is performed at least once between successive repetitions of step (a), and such that current flows in different closed loops which exclude the power supply.
Claim 17
Independent Claim
101 words
A method of applying current to a load, the method comprising the steps of: a) configuring a plurality of switches connected between the load and a power supply so that current flows from the power supply to the load and back to the power supply, b) reconfiguring the switches such that current flows through the load in a closed loop which excludes the power supply, and c) repeating steps (a) and (b) such that step (b) is performed at least once between successive repetitions of step (a), and such that current flows in different closed loops which exclude the power supply.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-11-14 | 1998-05-16 | 1998-11-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-11-14 | 2002-05-16 | 2002-11-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-11-14 | 2006-05-16 | 2006-11-15 | $7700.00 | Window Closed / Lapsed |