Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
This action is in response to the Response to Election/Restriction filed on 04/16/2026.
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 10/15/2025 is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
Election/Restrictions
Applicant’s election without traverse of claims 1-15 in the reply filed on 04/16/2026 is acknowledged.
Claim Objections
Claims 2, 4, and 14 are objected to because of the following informalities: Regarding claim 2, in line 3, “500 VAC and 2 kVAC and at least 750 VDC” appears that it should read as “500 VAC and 2 kVAC or at least 750 VDC”. Regarding claim 4, in line 2, “the primary and secondary windings” appears that it should read as “the first and second windings”. Regarding claim 14, in line 4, “with the at plurality of the DAB modules” appears that it should read as “with the plurality of the DAB modules”. Appropriate correction is required.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claim 14 s rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor, or for pre-AIA the applicant regards as the invention. Regarding claim 14, the claim is indefinite as the claim contains multiple antecedent basis issues: (i) “the input stages of a plurality of the DAB modules” lacks antecedent basis, since claim 1 recites “a first stage” and “a second stage”, not “input stages” and “output stages”; (ii) “the output stages of a plurality of the DAB modules” lacks antecedent basis for the same reason; (iii) “the primary winding of the planar transformer” lacks antecedent basis since claim 1 recites “a first winding”, not “a primary winding”; and (iv) “the secondary winding of the planar transformer” lacks antecedent basis since claim 1 recites “a second winding”, not “a secondary winding”. For purposes of examination, “the input stages” is interpreted as “input stages”, “the output stages” is interpreted as “output stages”, “the primary winding” is interpreted as “the first winding”, and “the secondary winding” is interpreted as “the second winding”.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1, 3, 6, 10, 11, and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Park et al. (Y. Park, S. Chakraborty and A. Khaligh, “DAB Converter for EV Onboard Chargers Using Bare-Die SiC MOSFETs and Leakage-Integrated Planar Transformer,” IEEE Transactions on Transportation Electrification, vol. 8, no. 1, pp. 209-224, March 2022, hereinafter “Park”) in view of Chen et al. (US Patent Application Publication US 2005/0270745 A1, hereinafter “Chen”). Regarding claim 1, Park discloses (see Fig. 1(b), Fig. 2, Fig. 3, Fig. 15 and Fig. 17) a dual active bridge (DAB) module (DAB converter prototype) comprising: a planar transformer comprising a first winding (primary winding), a second winding (secondary winding), and a magnetic core (planar E58/11/38-3C95 core; see p. 219 “E58/11/38-3C95 cores with two seven-turn, single-layer PCBs were used”); the first winding being formed as metallic traces on at least one first printed circuit board (PCB) and the second winding being formed as metallic traces on at least one second PCB (see p. 213 “two separate single-layer PCB windings are used for the third method”; see also Fig. 17(a) showing primary side winding board and secondary side winding board); a first plurality of transistors (S1-S4) formed on a PCB to form a first stage (primary side full-bridge module of Fig. 3(c); see p. 211 “all switches are soldered on the printed circuit board (PCB)”), the first transistors being controlled to provide a first current through the first winding based on an input voltage (V1=380 V) to provide a second current in the second winding (DAB primary-side switching with phase-shift modulation); and a second plurality of transistors (S5-S8) formed on a PCB to form a second stage (secondary side full-bridge module), the second transistors being controlled to provide an output voltage (V2=250-380 V) based on the second current. Park does not disclose the magnetic core being formed around at least a portion of the first PCB and the second PCB, with the first plurality of transistors and the second plurality of transistors integrated on the first and second PCBs, respectively. However, Chen teaches (see Figs. 4, 7C, and 7E) a power converter comprising a planar transformer integrated with power semiconductor switches, wherein the magnetic core wraps around the first and second windings of a multi-layer transformer substrate (see [0061] “magnetic core 72 may include two or more portions 72a, 72b that wrap around the first and second windings of the multi-layer transformer substrate 70”), and a portion of the magnetic core is received through openings formed in each of the layers of the multi-layer transformer substrate; and further wherein power semiconductor switches are mounted on the same multi-layer substrate as the transformer windings (see Fig. 7C; [0081] “single multi-layer switch substrate 70 comprising at least three electrically and thermally conductive layers”). Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the DAB module of Park such that the magnetic core is formed around at least a portion of the first PCB and the second PCB, and that the first and second pluralities of transistors are formed on the first and second PCBs respectively, as taught by Chen, because it can help reduce parasitic inductance and Ohmic losses related to inter-board connections, increase the magnetic core window utilization ratio, and increase the power density of the integrated planar transformer (see [0091] “increase in the magnetic core window utilization ratio, a reduction in the magnetic core value, and an increase in power density”). Regarding claim 3, Park further discloses liquid-cooled multifunctional components for higher power applications (see p. 212 “For higher power applications or more aggressive cooling, liquid-cooled MFCs can be adopted”) Park does not explicitly disclose wherein the planar transformer comprises at least one liquid cooling tube provided proximal to at least one of the first and second windings. However, Chen teaches (see Fig. 8) wherein the planar transformer (70) comprises at least one liquid cooling tube (94a and96b, see [0085] “conduit section 56b comprises an inlet 94a, an outlet 94b and a passage formed by first passage section 96a and second passage section 96b which are fluidly communicatingly coupled with the intake 94a and outtake 94b”) provided proximal to at least one of the first and second windings (the multi-layer transformer substrate (70) carrying the first and second windings is thermally coupled to the heat sink and arranged proximal to the conduit passages). Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the DAB module of Park in view of Chen to comprise at least one liquid cooling tube provided proximal to at least one of the first and second windings, as taught by Chen, because it can help transfer heat from the planar transformer windings and switching devices to the cooling fluid, thereby permitting operation at higher power densities while maintaining current and thermal stresses at acceptable levels. Regarding claim 6, Park discloses (see Fig. 1 (b) and Fig. 3(b)) wherein the first transistors are arranged as a first full bridge and wherein the second transistors are arranged as a second full bridge (see Fig. 1(b) showing first full-bridge S1-S4 and second full-bridge S5-S8; see also Fig. 3(b) p. 212 “Schematic of one full-bridge”).
Regarding claim 10, Park discloses (see Fig. 1 (b) and Fig. 3(b)) wherein at least one of the first and second transistors are arranged as metal oxide semiconductor field effect transistor (MOSFET) devices (see p. 209 Abstract “PCB-based, wire-bondless full-bridge module featuring bare-die SiC MOSFETs”).
Regarding claim 11, Park discloses (see Fig. 15) wherein at least one of the first and second transistors are arranged as silicon carbide (SiC) transistor devices (see p. 209 Abstract “bare-die SiC MOSFETs”; see also Table VI showing CPM2-1200-0025B SiC MOSFET).
Regarding claim 12, Park discloses (see Fig. 2(a)) wherein at least one of the first and second transistors are arranged as bare die transistor devices (see p. 211 “bare-die switches occupy significantly smaller footprint area than corresponding packaged devices”; see also Fig. 2(a) showing dimensions of the bare-die SiC MOSFET).
Claims 2, 7, 8, 9, 13, 14, and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Park in view of Chen, and further in view of Awal et al. (M. A. Awal et al., “Medium Voltage Solid State Transformer for Extreme Fast Charging Applications,” 2023 IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 1528-1535, 2023, hereinafter “Awal”). Regarding claim 2, Park does not disclose wherein the input voltage is one of between approximately 500 VAC and 2 kVAC or at least 750 VDC, and wherein the output voltage is one of between approximately 500 VAC and 2 kVAC or at least 750 VDC.
However, Awal teaches a single-phase module (SPM) using a DAB converter for a medium-voltage solid state transformer (see Table I “Nominal MVAC voltage 1.27 kV”; see also Table I “Nominal LV DC voltage 750 V”), wherein the input voltage (SPM nominal MV AC voltage of 1.27 kV) falls between approximately 500 VAC and 2 kVAC, and the output voltage (SPM nominal LV DC voltage of 750 V) falls within the range of at least 750 VDC.
Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the DAB module of Park wherein the input voltage is one of between approximately 500 VAC and 2 kVAC or at least 750 VDC, and wherein the output voltage is one of between approximately 500 VAC and 2 kVAC or at least 750 VDC, because it can help interface the DAB module with medium voltage AC distribution grids and provide a regulated 750 V DC bus suitable for electric vehicle extreme fast charging applications (see p. 1 of Awal, “Extreme fast charging (XFC) is one of the key enabling technologies to reduce range anxiety associated with electrified vehicles”). Regarding claim 7, Park does not disclose comprising a third plurality of transistors arranged as a third full bridge in the first stage, the third transistors being configured to convert the input voltage from an AC voltage to a DC voltage.
However, Awal teaches (see Fig. 2) comprising a third plurality of transistors arranged as a third full bridge in the first stage (an active-front-end (AFE) stage formed by a third full bridge, see p. 2 “Another NPC full-bridge is used as the AFE stage”), the third transistors being configured to convert the input voltage from an AC voltage to a DC voltage (the AFE stage is configured to convert an AC input voltage from an AC distribution grid to a DC voltage at an MV DC bus).
Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the DAB module of Park to comprise a third plurality of transistors arranged as a third full bridge in the first stage configured to convert an AC input voltage to a DC voltage, as taught by Awal, because it can help interface the DAB module directly with an AC distribution grid by performing AC/DC rectification at a front-end stage.
Regarding claim 8, Park does not disclose a third plurality of transistors arranged as a third full bridge in the second stage, the third transistors being configured to convert the output voltage from a DC voltage to an AC voltage.
However, Awal teaches (see Fig. 1) a third plurality of transistors arranged as a third full bridge in the second stage (an XFC station configuration in which DAB-based DC-DC modules deliver power to a low-voltage DC bus, see p. 1 “DC extreme fast charging (XFC) of electric vehicles”), the third transistors being configured to convert the output voltage from a DC voltage to an AC voltage (additional DC/AC inverter stages may be implemented as full-bridge structures to convert DC bus voltage to AC voltage). Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the DAB module of Park to comprise a third plurality of transistors arranged as a third full bridge in the second stage configured to convert the DC output voltage to an AC voltage, as taught by Awal, because it can help provide AC output capability for delivering power to AC loads and to enable bidirectional energy flow for grid-support functions. Regarding claim 9, Park does not disclose further comprising: a first logic circuit configured to control operation of the first transistors in response to at least one first control signal, a second logic circuit configured to control operation of the second transistors in response to at least one second control signal, and at least one fiber optic link between the first and second logic circuits to transfer logic signals between the respective first and second stages.
However, Awal teaches (see Fig. 2 and Fig. 3) a first logic circuit configured to control operation of the first transistors in response to at least one first control signal (see decentralized controller for DAB stage of Fig. 2), a second logic circuit configured to control operation of the second transistors in response to at least one second control signal (see decentralized controller for DAB stage of Fig. 2, and control architecture comprising a local logic controller for each DAB stage, i.e. as shown in Fig. 2, and plural DAB stages and a central controller as shown in Fig. 3), and at least one fiber optic link between the first and second logic circuits to transfer logic signals between the respective first and second stages (see p. 4 “The central controller uses three optical fibers, i.e., one per each phase, to transmit the gate pulses to the first three-phase block”). Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the DAB module of Park to comprise a first logic circuit configured to control operation of the first transistors in response to at least one first control signal, a second logic circuit configured to control operation of the second transistors in response to at least one second control signal, and at least one fiber optic link between the first and second logic circuits to transfer logic signals between the respective first and second stages, as taught by Awal, because it can help provide galvanic isolation between control circuits associated with the high-voltage primary side and the low-voltage secondary side while transmitting logic signals reliably without susceptibility to electromagnetic interference. Regarding claim 13, Park modified in view of Chen discloses the DAB module of claim 1 (see claim rejection of claim 1 above). Park does not disclose a voltage converter circuit comprising a plurality of the DAB modules and configured to convert an AC voltage to at least one DC voltage.
However, Awal teaches (see Fig. 2 and Fig. 3) a voltage converter circuit (modular solid state transformer for XFC) comprising a plurality of DAB modules (see each single-phase module as shown in Fig. 2, each comprising a DAB module, see p. 1 “A modular and scalable solid state transformer (SST) with direct medium voltage (MV) AC connectivity is proposed to enable DC extreme fast charging (XFC) of electric vehicles”), wherein the voltage converter circuit is configured to convert an AC voltage (medium voltage AC grid voltage 13.2 kV) to at least one DC voltage (750 V LV DC bus; see Table II “Nominal LV DC bus voltage 750 V”).
Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the DAB module of Park to be used in a voltage converter circuit comprising a plurality of the DAB modules and configured to convert an AC voltage to at least one DC voltage, as taught by Awal, because it can help provide a high-power AC-DC conversion system suitable for medium voltage grid-connected applications such as extreme fast charging stations.
Regarding claim 14, as best understood, Park does not disclose wherein the input stages of a plurality of the DAB modules that is a proper subset of the DAB modules are arranged in parallel with respect to the primary winding of the planar transformer in each of the respective plurality of the DAB modules, with the at plurality of the DAB modules being arranged in series with respect to the primary winding of the planar transformer of at least one other DAB module of the DAB modules, or wherein the output stages of a plurality of the DAB modules that is a proper subset of the DAB modules are arranged in series with respect to the secondary winding of the planar transformer in each of the respective plurality of the DAB modules, with the plurality of the DAB modules being arranged in parallel with respect to the secondary winding of the planar transformer of at least one other DAB module of the DAB modules. However, Awal teaches (see Fig. 2 and Fig. 3) wherein the input stages of a plurality of the DAB modules that is a proper subset of the DAB modules (see input stage of DAB of Fig. 2) are arranged in parallel with respect to the primary winding of the transformer in each of the respective plurality of the DAB modules (see transformer of Fig. 2 for each input stage DAB of the plural DABs in Fig. 3, where the input stages are arranged in parallel), with the plurality of the DAB modules being arranged in series with respect to the primary winding of the transformer of at least one other DAB module of the DAB modules (each of the DAB modules are arranged in series with respect to other transformers of other DAB modules as shown in Fig. 3, and see p. 1 “Single-phase-modules (SPMs), each consisting of an active-front-end (AFE) stage and an isolated DC-DC stage, are connected in input-series-output-parallel (ISOP) configuration”) or To reach the desired AC voltage level, N three-phase blocks are connected in ISOP configuration”). Regarding claim 15, Park modified in view of Chen and Awal discloses the voltage converter circuit of claim 13 (see claim rejection of claim 13 above). Park does not disclose an electric vehicle (EV) charging system comprising the voltage converter circuit. However, Awal teaches an electric vehicle charging system comprising the voltage converter circuit (see Fig. 1 “An XFC station using a modular SST for delivering power from an MVAC feeder to an LV DC bus enabling multiple ultra-fast DC charging ports”). Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the DAB module of Park to be used in an electric vehicle charging system comprising a voltage converter circuit, as taught by Awal, because it can help provide a high-power AC-DC conversion system suitable for medium voltage grid-connected applications such as extreme fast charging stations.
Claims 4 and 5 are rejected under 35 U.S.C. 103 as being unpatentable over Park in view of Chen, and further in view of Yoo et al. (Yoo, J.-S., Gil, Y.-M., Ahn, T.-Y., “High-Power-Density DC-DC Converter Using a Fixed-Type Wireless Power Transmission Transformer with Ceramic Insulation Layer,” Energies, vol. 15, 9006, November 2022, hereinafter “Yoo”). Regarding claim 4, Park does not disclose wherein the planar transformer further comprises at least one ceramic electrical insulator for electrically separating the first and second windings. However, Yoo teaches (see Figs. 4, 6, and 13(b)) a planar transformer comprising at least one ceramic electrical insulator for electrically separating a first winding and a second winding (see Abstract “A ceramic insulating layer was used instead of an air gap”), wherein the ceramic insulating layer is disposed between the primary side and the secondary side of the transformer (see p. 4 “an insulator such as ceramic and a material with low magnetic permeability is used as an air gap between the primary and secondary cores of the transformer”). Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the DAB module of Park to comprise at least one ceramic electrical insulator for electrically separating the first and second windings, as taught by Yoo, because it can help provide a heat dissipation path from the windings to an external metal case while maintaining electrical isolation between the primary and secondary sides (see Abstract of Yoo, “the heat generated from the transformer core and the PCB winding was quickly transferred to the external metal case, with the ceramic insulating layer acting as a heat pipe”). Regarding claim 5, Park does not disclose wherein the at least one ceramic insulating layer is configured to electrically isolate the primary side winding and primary side transistors from the secondary side winding and secondary side transistors. However, Yoo teaches (see Figs. 13(b) and 16) wherein the at least one ceramic insulating layer (see Abstract “A ceramic insulating layer was used instead of an air gap”) is configured to electrically isolate the primary side winding and primary side transistors from the secondary side winding and secondary side transistors (see Abstract “it was possible to physically separate the primary and secondary sides of the power circuit centering on the ceramic insulating layer”). Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the DAB module of Park wherein the at least one ceramic insulating layer is configured to electrically isolate the primary side winding and primary side transistors from the secondary side winding and secondary side transistors, as taught by Yoo, because it can help provide a heat dissipation path from the windings to an external metal case while maintaining electrical isolation between the primary and secondary sides (see Abstract of Yoo, “the heat generated from the transformer core and the PCB winding was quickly transferred to the external metal case, with the ceramic insulating layer acting as a heat pipe”).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure: US 2018/0076723 A1 discloses a wide-range variable direct current (DC) link power converter. US 2022/0399153 A1 discloses a power converter using a planar transformer assembly that provides medium-voltage isolation at high frequencies. US 2024/0304372 A1 discloses a dual-active bridge converter comprising a co-planar transformer.
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/MONICA LEWIS/ Supervisory Patent Examiner, Art Unit 2838
/JYE-JUNE LEE/Examiner, Art Unit 2838
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