DETAILED ACTION
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.
Claim(s) 1, 2, 6 and 7 is/are rejected under 35 U.S.C. 103 as being unpatentable over Wen et al. (CN106024497 cited in the Information Disclosure Statement filed March 29, 2024, hereafter Wen).
Claim 1: Wen teaches a switching device for disconnecting a current path in a DC supply system (Abstract and Figure 4), said current path comprising source-end and load-end inductances (inherent source-end and load-end inductances of conductors provided at the source-end and the load-end), the switching device comprising:
two series-connected switching modules (IGBTs in Figure 4), wherein each of the switching modules comprises three parallel branches (shown in Figure 4 and defined below);
the first branch including a first controllable semiconductor switching element (IGBT);
the second branch including a first resistor (R2) connected in series to a second resistor (R1) and then a first capacitor (C1);
the third branch including a second capacitor (C2) in series with a respective second switching element comprising a disconnectable thyristor (thyristor D1 and [0022], [0023], [0054], [0078] and [0080] where D1 is turned on and off, or connected and disconnected, in the time period between the IGBT starting to conduct commutation and turning off the current);
wherein a first node (node connecting IGBT, C2 and R2) joins the first end of all three branches so the first resistor (R2) is connected to a first load terminal of the first controllable semiconductor switching element (IGBT) and a second load terminal of the first controllable semiconductor switching element (node connecting IGBT, C1 and D1) is connected to the first capacitor (C1); and
a connecting leg runs from an intermediate node of the second branch (node connecting D1, C2, R1 and R2) to a respective intermediate node of the third branch (the node connecting D1, C2, R1 and R2 is the same node), wherein the intermediate node of the second branch is between the first resistor and the second resistor (node between R2 and R1) and the respective intermediate node of the third branch is between the second capacitor and the second switching element (node between C1 and D1).
Wen further teaches that the discharge time of the second capacitor is equal to the resistance of R2 times the capacitance value of the second capacitor ([0058]). Wen does not specifically teach that a desired discharge time of the first capacitor is set by the ratio of the resistance values of the resistors in the series circuit. However, the selection of a desired discharge time of the first capacitor is set by the ratio of the resistance values of the resistors in the series circuit for the switching device would have been chosen to ensure an optimal performance of the circuit. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to select a desired discharge time of the first capacitor is set by the ratio of the resistance values of the resistors in the series circuit when employing the switching device of Wen to maximize the overall performance of the switching device. Furthermore, such a provision of selecting a specific discharge time involves only routine design expedient.
Claim 2: Wen further teaches the respective second switching elements (D1) can be switched to a conducting state and a blocking state via a control signal ([0054], [0078] and [0080] where D1 is turned on and off in the time period between the IGBT starting to conduct commutation and turning off the current).
Claim 6: Wen further teaches that the thyristors can be turned off by a turn-off circuit (the inherent turn-off circuit that controls D1 in the manner described in [0058] and [0080]).
Claim 7: Wen further teaches that the first controllable semiconductor switching element (IGBT) is an element of the turn-off circuit ([0080] where when IGBT is turned off, the voltage across the IGB rises and the current will oscillate until the charging current on C2 drops to zero, turning off D1).
Claim 3 is rejected under 35 U.S.C. 103 as being unpatentable over Wen in view of Cairoli et al. (U.S. Patent 10,230,260, hereafter Cairoli).
Claim 3: Wen teaches the limitations of claim 1 above. Wen does not specifically teach that the respective second switching element (thyristor D1 of Wen) is an insulated-gate bipolar transistor.
Cairoli teaches a respective second switching elements comprise an insulated-gate bipolar transistor (column 2 lines 59-67).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use the further controllable semiconductor switching element taught by Cairoli in the circuit of Wen to provide a controlled turn off device (column 2 lines 59-67 of Cairoli).
Response to Arguments
Applicant’s arguments filed October 27, 2025 with respect to the rejection(s) of claim(s) 1 and 9 under 35 U.S.C. 102(a)(1) have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of 35 U.S.C. 103 as being unpatentable over Wen.
Applicant asserts that Wen does not teach setting a desired discharge time of the first capacitor based on the ratio of resistance values of the resistors in the series circuit. Examiner notes that Wen teaches that the discharge time of the second capacitor is equal to the resistance of R2 times the capacitance value of the second capacitor ([0058]). Wen does not specifically teach that a desired discharge time of the first capacitor is set by the ratio of the resistance values of the resistors in the series circuit. However, the selection of a desired discharge time of the first capacitor is set by the ratio of the resistance values of the resistors in the series circuit for the switching device would have been chosen to ensure an optimal performance of the circuit. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to select a desired discharge time of the first capacitor is set by the ratio of the resistance values of the resistors in the series circuit when employing the switching device of Wen to maximize the overall performance of the switching device. Furthermore, such a provision of selecting a specific discharge time involves only routine design expedient.
Conclusion
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/C.J.O/Examiner, Art Unit 2849
/Menatoallah Youssef/SPE, Art Unit 2849