US4721869A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protection circuit for an insulated gate bipolar transistor utilizing a two-step turn off
Assignee: Toshiba Corp
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Filing: 1986-02-06
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Granted: 1988-01-26
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Expires: 2006-02-06
Abstract
Abstract A driving circuit for an insulated gate bipolar transistor (IGBT) which has a power source, a gate voltage input circuit which supplies the voltage to a gate terminal of IGBT, a detecting circuit for detecting a collector to emitter voltage of the IGBT and an adjusting circuit for lowering the control signal. When an abnormality is detected by the detecting circuit, the adjusting circuit performs a dropping operation of the gate voltage of the IGBT immediately after the detection or after the passage of a predetermined time following the application of the ON signal to the gate.
Inventors
- 👤 Chihiro Okado
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:45
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/08; H03K17/082; H03K17/0828
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
191 words
A protection circuit for an insulated gate bipolar transistor (IGBT) comprising: (a) a gate voltage input circuit for generating a gate voltage, and for supplying same to a gate of said IGBT; (b) a load connected in series with said IGBT; (c) a first detecting circuit means connected in circuit with said load for detecting an abnormality in said load; (d) adjusting circuit means responsive to said first detecting circuit means and connected to said gate voltage input circuit for adjusting said gate voltage of the IGBT; (e) a second detection circuit means for detecting whether an operation time of the adjusting circuit means exceeds a predetermined period, said second detection circuit means connected to said adjusting circuit means; and (f) wherein said adjusting circuit means first adjusts the gate voltage to a low voltage which is no less than a gate threshold voltage of the IGBT to decrease a fault current of said IGBT when the collector to emitter voltage of the IGBT is increased and, after elapse of said predetermined period adjusts the gate voltage to a voltage less than the threshold level to cut off the fault current.
Claim 2
Dependent Claim
191 words
A protection circuit for an insulated gate bipolar transistor (IGBT) comprising: (a) a gate voltage input circuit for generating a gate voltage, and for supplying same to a gate of said IGBT; (b) a load connected in series with said IGBT; (c) a first detecting circuit means connected in circuit with said load for detecting an abnormality in said load; (d) adjusting circuit means responsive to said first detecting circuit means and connected to said gate voltage input circuit for adjusting said gate voltage of the IGBT; (e) a second detection circuit means for detecting whether an operation time of the adjusting circuit means exceeds a predetermined period, said second detection circuit means connected to said adjusting circuit means; and (f) wherein said adjusting circuit means first adjusts the gate voltage to a low voltage which is no less than a gate threshold voltage of the IGBT to decrease a fault current of said IGBT when the collector to emitter voltage of the IGBT is increased and, after elapse of said predetermined period adjusts the gate voltage to a voltage less than the threshold level to cut off the fault current.
Claim 3
Dependent Claim
51 words
A protection circuit according to claim 1, wherein said adjusting circuit means comprises a voltage divider circuit composed of a plurality of resistors connected in series, at least one of which is activated by a transistor which is turned on in response to the output of the first detection circuit means.
Claim 4
Dependent Claim
61 words
A protection circuit according to claim 1, wherein said adjusting circuit means comprises a voltage divider circuit composed of a first resistor and a parallel connected capacitor and a second resistor connected in series with said first resistor, the second resistor being activated by a transistor which is turned on in response to the output of the first detection circuit means.
Claim 5
Dependent Claim
38 words
A protection circuit according to claim 1, wherein said first detecting circuit means comprises a voltage divider circuit which includes a plurality of resistors and outputs a proportion value of the collector to emitter voltage of the IGBT.
Claim 6
Dependent Claim
24 words
A protection circuit according to claim 1, further comprising a third detection circuit means for detecting whether the adjusting circuit means is in operation.
Claim 7
Dependent Claim
26 words
A protection circuit according to claim 5, wherein said third detection circuit means comprises a photocoupler which operates by current flowing through the adjusting circuit means.
Claim 8
Dependent Claim
24 words
A protection circuit according to claim 5, wherein said third detection circuit means comprises a current detector which detects collector current of the IGBT.
Claim 9
Dependent Claim
18 words
A protection circuit according to claim 1, wherein said adjusting circuit means is inoperable for the predetermined period.
Claim 10
Dependent Claim
24 words
A protection circuit according to claim 1, wherein said control signal is set to OFF to turn off the IGBT after the predetermined period.
Claim 11
Dependent Claim
135 words
A protection circuit for an insulated gate bipolar transistor (IGBT) comprising: a gate voltage input circuit means for converting an input control signal to a driving signal and forming a gate voltage of the IGBT by amplifying said driving signal; a detecting circuit means for detecting a collector to emitter voltage of said IGBT; and an adjusting circuit means for adjusting the driving signal to control the gate voltage of the IGBT based on the output of the detecting circuit means; whereby the control of the IGBT is performed so that the gate voltage of the IGBT is adjusted by varying the driving signal according to a function of the collector to emitter voltage which is selected within a safe operation area (SOA) region and the control is stopped when the adjusting circuit operates continuously.
Claim 12
Dependent Claim
135 words
A protection circuit for an insulated gate bipolar transistor (IGBT) comprising: a gate voltage input circuit means for converting an input control signal to a driving signal and forming a gate voltage of the IGBT by amplifying said driving signal; a detecting circuit means for detecting a collector to emitter voltage of said IGBT; and an adjusting circuit means for adjusting the driving signal to control the gate voltage of the IGBT based on the output of the detecting circuit means; whereby the control of the IGBT is performed so that the gate voltage of the IGBT is adjusted by varying the driving signal according to a function of the collector to emitter voltage which is selected within a safe operation area (SOA) region and the control is stopped when the adjusting circuit operates continuously.
Claim 13
Dependent Claim
32 words
A protection circuit according to claim 10, wherein the adjusting circuit means comprises a voltage divider circuit for applying a proportion of the collector to emitter voltage to the adjusting circuit means.
Claim 14
Dependent Claim
34 words
A protection circuit according to claim 10, wherein said adjusting circuit means comprises a resistor and a Zener diode connected in series whereby said gate voltage is obtained by turning on the Zener diode.
Claim 15
Dependent Claim
28 words
A protection circuit according to claim 10, wherein the adjusting circuit means cuts off the IGBT after detecting that a main current has reached a predetermined set value.
Claim 16
Dependent Claim
31 words
A protection circuit according to claim 10, wherein said detecting circuit means further comprises a photocoupler which detects a voltage drop caused by a current flowing through the adjusting circuit means.
Claim 17
Dependent Claim
25 words
A protection circuit according to claim 10, wherein said detecting circuit means further comprises a current detector which detects the collector current of the IGBT.
References Cited (Backward Citations)
US4360744A
Cited
US4301490A
Cited
US4363068A
Cited
US4363064A
Cited
US4543494A
Cited
US4536816A
Cited
US4612457A
Cited
US4591734A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-01-25 | 1991-07-27 | 1992-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-25 | 1995-07-27 | 1996-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-25 | 1999-07-27 | 2000-01-26 | $7700.00 | Window Closed / Lapsed |