DETAILED ACTION
This Office action is in response to the application filed on 19 February 2025.
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 .
Priority
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55.
Drawing
The drawing is objected to because of the following informalities:
Fig. 3B uses the same number (310) at three phase electrical generator and first dc output terminal.
Claim Rejections - 35 USC § 103
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.
Claims 1-5, 13-20 are rejected under 35 U.S.C. 103 as being unpatentable over David Trainer et. al (US20230373319A1; hereafter “David”) in view of Siyuan Liang et. al (Study on the Current Limiting Performance of a Novel SFCL in DC Systems; hereafter “Liang”).
-Regarding claim 1:
David discloses:
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A power electronics converter (Fig. 3A; 320) comprising: an input terminal (Fig. 3A; 311a, b, c); first and second DC output terminals (Fig. 3A; two black squares on 330) ; a branch comprising first and second semiconductor switches connected in series between the first and second DC output terminals (Fig. 3A; 322 and 324 connected in series between two black squares), the input terminal connected to a node between the first and second semiconductor switches (Fig. 3A; 311a,b, c connected to nodes of red circles); a DC link capacitor connected between the first and second DC output terminals (Fig. 3A; 328); and
Liang, in the same field of endeavor, discloses:
a resistive damping element connected in series with the DC link capacitor (Fig. 3; SFCL), wherein a damping factor of a circuit comprising the DC link capacitor, the resistive damping element and an inductance of the circuit with a short (Fig. 1; novel DC SFCL includes resister, inductor, and switch) between the output terminals is at least 1 (table I and Fig. 4).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the device described in David such that a commonly used superconducting current fault limiter (SFCL) described in Liang is applied to the power electronics converter. Doing so allows for improving DC power system fault protection.
-Regarding claim 2:
Liang discloses:
The power electronics converter of claim 1, wherein the resistive damping element (Fig. 1; SFCL) comprises a damping resistor connected in parallel with a damping inductor (Fig. 2 b).
-Regarding claim 3:
Liang discloses:
The power electronics converter of claim 2, wherein an impedance of the damping inductor is at least ten times the impedance of the damping resistor at a resonant frequency of the circuit (table I; superconducting coil L).
-Regarding claim 4:
David discloses:
The power electronics converter of claim 3, wherein the resonant frequency Fo of the circuit is defined as F° where L is the inductance of the circuit with a short between the output terminals and C is a capacitance of the DC link capacitor (paragraph 0097).
-Regarding claim 5:
Liang discloses:
The power electronics converter of claim 3, wherein a DC resistance of the damping inductor is less than 10% of a resistance of the damping resistor (table I; superconducting coil L).
-Regarding claim 13:
David discloses:
The power electronics converter of claim1, further comprising a reverse-biased DC link diode connected across the DC link capacitor (Fig. 5B; 509).
-Regarding claim 14:
David discloses:
The power electronics converter of claim 1, wherein the power electronics converter is an AC to DC converter (Fig. 3A; 300) and comprises a plurality of said branches -2- connected between the first and second DC output terminals (Fig. 3A;321a,b,c branches between two black squares on 330), the node between the first and second semiconductor switches of each branch being connectable to a respective phase of an electrical machine (Fig. 3A; red circles between 322 and 324 connected to each of 310).
-Regarding claim 15:
David discloses:
An electrical power system comprising: an electrical machine (Fig. 3A; 310); a DC network (Fig. 3A; 330); and a power electronics converter (Fig. 3A; 320) according to claim1 wherein the electrical machine is connected to the node of the power electronics converter (Fig. 3A; 310 coupled to red circles) and the DC network is connected across the first and second output terminals (Fig. 3A; DC network coupled to two black squares).
-Regarding claim 16:
David discloses:
The electrical power system of claim 15 further comprising a controller configured to provide switching signals to each switch of the power electronics converter (Fig. 3A; 340, paragraph 0068; “the controller 340 uses pulse width modulation to control the switching of the transistors to commutate current”).
-Regarding claim 17:
David discloses:
The electrical power system of claim 16, wherein the controller is configured to detect a DC fault in the DC network and, upon detecting the DC fault, open each of the semiconductor switches until a detected DC level across the DC network falls below a predefined threshold (paragraph 0024; “The controller may be configured to detect a DC fault in the DC network and, upon detecting the DC fault, open each of the semiconductor switches until a detected DC level across the DC network falls below a predefined threshold.”).
-Regarding claim 18:
David discloses:
An aircraft power and propulsion system (Fig. 1, 2) comprising: a gas turbine engine; and an electrical power system (Fig. 3A; 310) according to claim 15, wherein the electrical machine of the electrical power system is mechanically coupled with a spool of the gas turbine engine (claim 15).
-Regarding claim 19:
David discloses:
An aircraft comprising the power and propulsion system of claim 18 (claim 16).
-Regarding claim 20:
David discloses:
The aircraft of claim 19, wherein the aircraft is a hybrid electric aircraft (claim 17).
Allowable Subject Matter
Claims 6-12 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim.
The following is a statement of reasons for the indication of allowable subject matter:
-with respect to claim 6:
the prior arts in David, and Liang disclose the claimed invention in basic claims but do not further disclose about “a first inductor connected between a first terminal of the DC link capacitor and the first DC output terminal; and a second inductor connected between a second terminal of the DC link capacitor and the second DC output terminal.”.
-with respect to claim 12:
the prior arts in David, and Liang disclose the claimed invention in basic claims but do not further disclose about “a forward biased diode connected in parallel across a damping resistor.”.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to SEUNG HO CHOI whose telephone number is (571)272-8188. The examiner can normally be reached Monday-Thursday, 7:30 AM - 5:30 PM ET.
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/SEUNG HO CHOI/Examiner, Art Unit 2838
/CRYSTAL L HAMMOND/Supervisory Primary Examiner, Art Unit 2838
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