Ford Global Technologies, LLC

Patent Trials and Appeals Board

Jan 26, 2021

2020002153 (P.T.A.B. Jan. 26, 2021)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
15/067,878 03/11/2016 Zhuxian Xu 83586718 7500
28395 7590 01/26/2021
BROOKS KUSHMAN P.C./FGTL
1000 TOWN CENTER
22ND FLOOR
SOUTHFIELD, MI 48075-1238
EXAMINER
AGARED, GABRIEL T
ART UNIT PAPER NUMBER
2846
NOTIFICATION DATE DELIVERY MODE
01/26/2021 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
docketing@brookskushman.com
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte ZHUXIAN XU, CHINGCHI CHEN, KE ZOU XI LU, MICHAEL
W. DEGNER, and JUN KIKUCHI
____________

Appeal 2020-002153
Application 15/067,878
Technology Center 2800
____________

Before LINDA M. GAUDETTE, MICHAEL G. McMANUS, and
JANE E. INGLESE, Administrative Patent Judges.

INGLESE, Administrative Patent Judge.

DECISION ON APPEAL
Appellant1 requests review under 35 U.S.C. § 134(a) of the
Examiner’s final rejection of claims 1–18.2 We have jurisdiction under 35
U.S.C. § 6(b).
We REVERSE.

1 We use the word “Appellant” to refer to the “applicant” as defined in 37
C.F.R. § 1.42. Appellant identifies Ford Global Technologies, LLC as the
real party in interest. Appeal Brief filed July 8, 2019 (“Appeal Br.”) at 1.
2 Final Office Action entered January 4, 2019 (“Final Act.”) at 1.
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Application 15/067,878

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CLAIMED SUBJECT MATTER
Appellant claims a vehicle (independent claim 1), a method of
controlling an IGBT of a power system (independent claim 8), and a vehicle
powertrain (independent claim 13). Appeal Br. 3. Independent claims 1, 8,
and 13 illustrate the subject matter on appeal, and read as follows:
1. A vehicle comprising:
an electric machine;
an IGBT having a gate, an emitter, and a collector,
configured to flow an electric charge through a phase of the
electric machine; and
a gate driver configured to flow current onto the gate at
a first level, and in response to a time integral of a voltage
across the phase exceeding a predetermined level, transition
from the first level to a second level less than the first level.

8. A method of controlling an IGBT of a power system
comprising:
by a gate driver, flowing a current at a first level onto a
gate of an IGBT; and
in response to a time integral of a voltage across the
IGBT exceeding a predetermined threshold, transitioning the
current from the first level to a second level less than the first
level.

13. A vehicle powertrain comprising;
an IGBT having a gate, an emitter and a collector; and
a gate driver configured to flow current onto the gate at
a first level, and in response to a time integral of resulting
collector to emitter voltage exceeding a predetermined level,
transition from the first level to a second level less than the first
level.

Appeal Br. 9–10 (Claims Appendix) (emphasis added).

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REJECTIONS
The Examiner maintains the following rejections in the Examiner’s
Answer entered November 18, 2019 (“Ans.”):
I. Claims 8–18 under 35 U.S.C. § 102(a) as anticipated by
Wagoner et al. (US 2015/0162905 A1, published June 11, 2015)
(“Wagoner”); and
II. Claims 1–7 under 35 U.S.C. § 103 as unpatentable over
Miyauchi et al. (US 2013/0229209 A1, published September 5, 2013)
(“Miyauchi”) in view of Wagoner.
FACTUAL FINDINGS AND ANALYSIS
Upon consideration of the evidence relied upon in this appeal and
each of Appellant’s contentions, we reverse the Examiner’s rejections of
claims 1–18 for reasons set forth in the Appeal and Reply Briefs, and below.
We need address only independent claims 1, 8, and 13, which recite,
in part, a gate driver configured to flow current onto a gate of an IGBT at a
first level, and to transition from the first level to a second level less than the
first level in response to a time integral of a voltage across a phase of an
electric machine, a time integral of a voltage across the IGBT, or a time
integral of collector to emitter voltage, respectively, exceeding a
predetermined level.
Wagoner discloses IGBT 210 including gate 212, collector 214, and
emitter 216. Wagoner ¶ 31; Fig. 2. Wagoner discloses gate drive circuit
300 including active gate control circuit 310 configured to apply voltages via
gate resistor 312 to gate 212 of IGBT 210. Wagoner ¶ 34; Fig. 3. Wagoner
discloses that active gate control circuit 310 can provide four different
voltage levels via gate resistor 312 to gate 212 of IGBT 210, including a first
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voltage that is sufficiently greater than the threshold voltage for IGBT 210
so that IGBT 210 is fully on. Wagoner ¶¶ 39, 40. Wagoner discloses that
after receiving a turn off signal to turn off IGBT 210, active gate control
circuit 310 can apply a second voltage to gate 212 of IGBT 210 that is
sufficiently less than the threshold voltage for IGBT 210 so that IGBT 210 is
fully off. Wagoner ¶¶ 13, 41. Wagoner discloses that during turn off of
IGBT 210, active gate control circuit 310 can operate IGBT 210 for a first
turn off time period, followed by a second turn off time period. Wagoner
¶ 42. Wagoner discloses that during the first time off period, active gate
control circuit 310 can apply a third voltage to gate 212 of IGBT 210 that is
less than the first voltage and greater than the second voltage. Wagoner
¶ 43. Wagoner discloses that during the second time off period, active gate
control circuit 310 can apply a fourth voltage to gate 212 of IGBT 210 that is
less than the third voltage and greater than the second voltage. Wagoner
¶ 44.
Wagoner describes Figures 6 and 7 in paragraphs 56 and 57, and
explains that these figures “depict simulation results for an example gate
drive circuit for an IGBT.” Wagoner ¶¶ 56, 57. Wagoner discloses that
waveform 610 shown in Figure 6 “depicts the voltage applied by an example
active gate control circuit to the gate of an IGBT,” and shows that “the
active gate control circuit can apply a voltage of about 15V when the IGBT
is turned on, a voltage of about 4V for the first turn off period, a voltage of
about 4V for the second turn off period, and a voltage of about -7V when the
IGBT is turned off.” Wagoner ¶ 56. Wagoner discloses that waveform 620
shown in Figure 6 “depicts the collector-emitter voltage VCE associated with
forward flowing collector current (e.g. current in the IGBT) during turn off,”
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and waveform 630 shown in Figure 6 depicts “collector current IC for
forward flowing collector current.” Wagoner ¶ 57. Wagoner discloses that
waveform 640 shown in Figure 7 “depicts the collector-emitter voltage VCE
associated with reverse flowing collector current (e.g. current in
freewheeling diode) during turn off,” and waveform 650 shown in Figure 7
“depicts the collector current IC for reverse flowing collector current.” Id.
The Examiner determines that “based on the broadest reasonable
interpretation,” a “time integral” as recited in the present independent claims
is “interpreted and understood by the examiner as a time period.” Ans. 5.
The Examiner finds that, consequently, the description provided in
paragraphs 56 and 57 of Wagoner, and the plots of voltage vs. time shown in
Wagoner’s Figures 6 and 7, “clearly meet” the limitation in the independent
claims of “in response to a time integral of a voltage . . . exceeding a
predetermined level, transition from the first level to a second level less than
the first level.” Ans. 6. The Examiner finds that “[t]his is also further
evidenced by the appellant’s dependent claims 6 and 11 where the time
integral is defined as . . . ‘the time integral is for a period beginning when
the gate driver receives an IGBT turn-on signal and ending when the gate
driver turns off the IGBT.’” Id.
As Appellant argues, however, the Examiner’s interpretation of a
“time integral” as recited in the present independent claims as a “time
period” is unreasonably broad because such an interpretation is inconsistent
with the plain meaning of a “ time integral,” and with how this phrase is
used in Appellant’s Specification. Reply Br. 2–3.
Specifically, the plain and ordinary meaning of a “time integral” is
“an integral of a variable or function with respect to time; an expression of
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which a given function is the time derivative.” Lexico,
https://www.lexico.com/en/ definition/time_integral. Although we do not
find an explicit definition of a “time integral” in Appellant’s Specification,
the Specification uses this term in a manner that is consistent with its plain
meaning. See, e.g., Spec. ¶ 54 (“the transition time may be in response to an
integral over a time period, also referred to as a time integral, of a load
driven by the IGBT exceeding a reference threshold”); see also Spec. ¶ 57
(“[t]he controller of the IGBT device may calculate or receive as an input the
time integral of a voltage across a phase of the electric machine coupled with
the IGBT”); Spec. ¶ 58 (“Here, initial gate current drive time is gradually
increased until the time integral of the voltage of the load (such as a phase of
the electric machine for an inverter or an inductor load for a DC-DC
converter) exceeds a predetermined threshold”); Spec. ¶ 61 (“[o]ne circuit to
measure a time integral of the voltage between the emitter and collector of
the IGBT 604 is to enable the MOSFET 612”).
Consistent with the disclosures in Appellant’s Specification, and
according to the plain meaning of a “time integral,” we interpret “a time
integral of a voltage” as recited in independent claims 1, 8, and 13 as an
integral of voltage with respect to time, which is distinct from a period of
time. In re ICON Health and Fitness, Inc., 496 F.3d 1374, 1379 (Fed. Cir.
2007) (During prosecution of patent applications, “the PTO must give claims
their broadest reasonable construction consistent with the specification. . . .
Therefore, we look to the specification to see if it provides a definition for
claim terms, but otherwise apply a broad interpretation.”); In re Zletz, 893
F.2d 319, 321 (Fed. Cir. 1989) (the words of a claim must be given their
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plain meaning unless the plain meaning is inconsistent with the
specification.).
Yet, as discussed above, the Examiner determines that dependent
claims 6 and 11 define “time integral” according to the Examiner’s
interpretation as a “time period.” Ans. 6. But as Appellant points out, the
recitation in claims 6 and 11 of “the time integral is for a period beginning
when the gate driver receives an IGBT turn-on signal and ending when the
gate driver turns off the IGBT” indicates that the time integral is for a
specified period of time, rather than indicating that the time integral is a
period of time. Reply Br. 2, fn. 1.
The Examiner’s interpretation of “a time integral of a voltage” as
being a time period is, therefore, unduly broad. In re Suitco Surface, Inc.,
603 F.3d 1255, 1260 (Fed. Cir. 2010) (explaining that the broadest
reasonable interpretation standard does not give the Patent Office an
unfettered license to interpret the words in a claim without regard for the full
claim language and the written description.)
Because the Examiner’s rejection of claims 8–18 under 35 U.S.C.
§ 102(a), and rejection of claims 1–7 under 35 U.S.C. § 103, are based on
this unreasonably broad claim interpretation, we do not sustain the
Examiner’s rejections. Final Act. 3–7; Ans. 5.

CONCLUSION

Claims
Rejected

35 U.S.C. § Reference(s)/Basis Affirmed Reversed
8–18 102 Wagoner 8–18
1–7 103 Miyauchi,
Wagoner
1–7
Appeal 2020-002153
Application 15/067,878

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Claims
Rejected

35 U.S.C. § Reference(s)/Basis Affirmed Reversed
Overall
Outcome
1–18

REVERSED