Ford Global Technologies, LLCDownload PDFPatent Trials and Appeals BoardJan 26, 20212020002153 (P.T.A.B. Jan. 26, 2021) Copy Citation 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. Appeal 2020-002153 Application 15/067,878 2 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). Appeal 2020-002153 Application 15/067,878 3 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 Appeal 2020-002153 Application 15/067,878 4 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,” Appeal 2020-002153 Application 15/067,878 5 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 Appeal 2020-002153 Application 15/067,878 6 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 Appeal 2020-002153 Application 15/067,878 7 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 8 Claims Rejected 35 U.S.C. § Reference(s)/Basis Affirmed Reversed Overall Outcome 1–18 REVERSED Copy with citationCopy as parenthetical citation