DETAILED ACTION
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 .
Response to Amendment
The Amendments, filed on 12/19/25 have been received and made of record. In response to the most recent Office Action, dated 09/22/25, claims 2-14 and 16-17 have been amended. Currently claims 9 and 12-29 are withdrawn as they are directed towards unelected species’. Claims 1-8 and 10-11 are currently pending.
Response to Arguments
Applicant’s Amendments, filed on 12/19/25, have been entered and fully considered. The amendments made to the claims were made to remedy issues within the claims that were objected to in the most recent Office Action. In regards to claim 1, the Applicant has presented a set of arguments pointing out their rational of how the prior art references made of record in the most recent Office Action do not teach the currently recited claim limitations. Applicant's arguments have been fully considered but they are not persuasive.
The Applicant in their submitted remarks argues that the combination Kim (KR 20200003587 A) in view of Zhong (US 2022/0085657 A1) does not teach all the limitations of claim 1 and specifically the combination does not teach the limitation of “wherein a phase shift is introduced between the gate signal of one of the primary switches and the gate signal of a corresponding one of the secondary switches”. The first argument presented by the Applicant is reproduced below for purposes of clarity and is also found on page 10 of the submitted remarks:
Although paragraph [0057] of Zhong discloses that both the primary and secondary sides employ a full-bridge phase-shift configuration, Zhong does not disclose or suggest that the phase-shifting technique can be applied to a three-phase circuit architecture. Specifically, Zhong only describes a single-phase converter topology and provides no teaching, motivation, or technical indication that such phase-shifting control could be extended to a three-phase system, such as the configuration used in Kim. Zhong does not disclose, teach or suggest applying phase- shifting technique to a single-stage three-phase rectifier. Accordingly, Zhong does not provide any technical suggestion or rationale that would lead a person skilled in the art to apply the phase-shifting operation of the primary and secondary sides disclosed in Zhong to the three- phase structure of Kim. Therefore, Applicant respectfully submits that the combination proposed by the Examiner would not have been obvious to one skilled in the art.
According to Zhong's disclosure, the core of the Zhong's solution lies in a single-phase system, where "there are three control degrees of freedom in the system, which, in sequence, are: a phase shift angle a of the inverter on the primary side, a phase shift angle R of the rectifier on the secondary side, and a phase angle y of the control voltage ugs5 of the top switch in the first bridge arm of the secondary-side rectifier." Under this framework, Zhong's scheme inherently entails high control complexity-even in single-phase or two-phase topologies, the control methodology presents substantial challenges, not to mention its adaptation to a single-stage three-phase topology, which is structurally far more complex.
The Examiner respectfully disagrees and would like to start off by reminding the Applicant that the test for obviousness is not whether the features of a secondary reference may be bodily incorporated into the structure of the primary reference; nor is it that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981). Also, one cannot show non-obviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). Zhong was combined with Kim not to change the number of phases on the primary side rather Zhong was combined to show that by adding secondary switches on the secondary side with a phase shift from the primary side would help regulate the output voltage dynamically and compensate for input variations and load changes. Zhong teaches that a phase shift can be applied between a primary side and a secondary side switching to control the transfer of power. It would have been obvious to one of ordinary skill to apply this known control technique to the converter of Kim as a predictable use of prior elements according to their established functions. Furthermore, the claims as currently recited do not recite any limitations of how the phase shift is tied to the three phases at the input it merely recites that it is tied to switches on the primary side. As for the Applicant’s argument regarding the complexity of the combination, this argument does not demonstrate that the proposed combination would be inoperable or beyond the level of ordinary skill in the art.
The second argument presented by the Applicant is reproduced below for purposes of clarity and is also found on page 10 of the submitted remarks:
Moreover, Kim does not disclose phase-shift control between the plurality of primary switches and the plurality of secondary switches located in the output stage as mentioned in the present application. This is further corroborated by Kim's disclosed topology and associated figures, which show that the output stage/secondary side employs only synchronous rectification diodes, not active switches.
The Examiner respectfully disagrees and would like to point out that although Kim does not teach the plurality of active switching on the secondary side, Zhong does teach the use of active switching on the secondary side. Substituting such known equivalents for rectification is well known in the art and furthermore it has been provided that there is an advantage that one of ordinary skill would be able to attain from the combination and use of secondary side active switches as pointed out below and above. The Examiner believes that all arguments have been addressed and based on those reasonings provided above the Examiner stands by the rejection provided previously.
Claim Rejections
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 (i.e., changing from AIA to pre-AIA ) 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.
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 1-8 and 10-11 are rejected under 35 U.S.C. 103 as being unpatentable over Kim (KR 20200003587 A) in view of Zhong (US 2022/0085657 A1).
Regarding claim 1, Kim teaches an AC/DC converter (Figure 4; Figure 4 has been annotated below as Figure 4A for purposes of clarity for specific elements not labeled), comprising: a plurality of internal terminals including a positive terminal (Annotated Figure 4A Component Pos), a negative terminal (Annotated Figure 4A Component Neg), and a neutral terminal (Annotated Figure 4A Component Neu); an input stage (Annotated Figure 4A Component IS) electrically coupled to the positive, negative, and neutral terminals (Annotated Figure 4A Component IS is coupled to Component Pos at the top terminal, Component Neg at the bottom terminal and Component Neu at the input terminals through the inductors La, Lb and Lc and capacitors Ca, Cb and Cc) and including at least three input terminals that are connectable to a three-phase AC power source (Annotated Figure 4A Component IS has three input terminal connected to an AC source, Components Va, Vb and Vc); a switching stage (Annotated Figure 4A Component SS) including a plurality of primary switches electrically coupled between the positive and negative terminals (Annotated Figure 4A Components S1-S4); an output stage (Annotated Figure 4A Component OS) electrically coupled to the switching stage and the neutral terminal (Annotated Figure 4A Component OS is coupled to Component SS through node ‘a’ and is coupled to Component Neu through node ‘b’), the output stage including output terminals that are connectable to a load (Annotated Figure 4A Component OS outputs a voltage Vo that is connected to a load), thereby providing a DC voltage to the load (Annotated Figure 4A Component Vo), wherein the output stage comprises a transformer (Annotated Figure 4A Component OS Transformer) and a secondary side rectifier circuit (Annotated Figure 4A Components DR1 and DR2); and a controller electrically coupled to the switching stage (Annotated Figure 4A Components S1-S4 receive a switching signal from a controller even though it is not shown in the Figure).
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Kim does not teach wherein the output stage comprises an active bridge including a plurality of secondary switches; and a controller electrically coupled to the switching stage and the output stage to generate gate signals for the primary and secondary switches, wherein a phase shift is introduced between the gate signal of one of the primary switches and the gate signal of a corresponding one of the secondary switches.
Zhong teaches an AC/DC converter (Figure 2), comprising: an AC source (Figure 2 Component Ugrid); an input stage electrically coupled to the AC power source (Figure 2 Component Diode Rectifier); an EMI filter connected to the output of the AC power source and connected between the AC power source and the input stage (Figure 2 Component EMI Filter); a switching stage including a plurality of primary switches (Figure 2 Components S1-S4); an output stage (Figure 2 Components L1, L2 and S5-S8) electrically coupled to the switching stage (Figure 2 Component L1 is coupled to Components S1-S4), the output stage including output terminals that are connectable to a load (Figure 2 Component RL), thereby providing a DC voltage to the load (Figure 2 Component Vo), wherein the output stage comprises a transformer (Figure 2 Component Transformer made up by windings L1 and L2) and an active bridge including a plurality of secondary switches (Figure 2 Components S5-S8); and a controller electrically coupled to the switching stage and the output stage to generate gate signals for the primary and secondary switches (Figure 2 does not show a controller, however, Paragraph 0058 and Figure 5 indicate the presence of a controller), wherein a phase shift is introduced between the gate signal of one of the primary switches and the gate signal of a corresponding one of the secondary switches (Paragraph 0058; Figure 5).
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 teachings of Kim to incorporate the use of an EMI filter at the input and an active secondary output stage comprising switches as taught by Zhong. The EMI filter provides the benefit of suppressing high-frequency electrical noise that can cause malfunctions or damage to sensitive components. The benefit of the secondary side active output stage made up of switches instead of diodes is that with a controlled secondary side the voltage regulation is enhanced allowing for regulating the output voltage dynamically and compensating for input variations and load changes.
Regarding claim 2, Kim and Zhong teach all the limitations of claim 1. Kim further teaches wherein the switching stage comprises two active switches (Annotated Figure 4A Components S2 and S3) and wherein a midpoint of the two active switches is electrically coupled to the neutral terminal (Annotated Figure 4A Components S2 and S3 have a midpoint connected to node ‘b’ which is the neutral terminal connection).
Regarding claim 3, Kim and Zhong teach all the limitations of claim 1. Kim further teaches wherein the input stage comprises a three-phase diode bridge (Annotated Figure 4A Component IS).
Regarding claim 4, Kim and Zhong teach all the limitations of claim 1. Kim further teaches a plurality of boost inductors (Annotated Figure 4A Components La, Lb, Lc), each being electrically coupled between a corresponding input terminal of the three-phase AC power source and a corresponding leg of the three-phase diode bridge (Annotated Figure 4A Components La, Lb and Lc are connected to each input of the diode bridge and to each phase of the AC source, respectively).
Kim does not teach an EMI filter.
Zhong teaches an AC/DC converter (Figure 2), comprising: an AC source (Figure 2 Component Ugrid); an input stage electrically coupled to the AC power source (Figure 2 Component Diode Rectifier); an EMI filter connected to the output of the AC power source and connected between the AC power source and the input stage (Figure 2 Component EMI Filter); a switching stage including a plurality of primary switches (Figure 2 Components S1-S4); an output stage (Figure 2 Components L1, L2 and S5-S8) electrically coupled to the switching stage (Figure 2 Component L1 is coupled to Components S1-S4), the output stage including output terminals that are connectable to a load (Figure 2 Component RL), thereby providing a DC voltage to the load (Figure 2 Component Vo), wherein the output stage comprises a transformer (Figure 2 Component Transformer made up by windings L1 and L2) and an active bridge including a plurality of secondary switches (Figure 2 Components S5-S8); and a controller electrically coupled to the switching stage and the output stage to generate gate signals for the primary and secondary switches (Figure 2 does not show a controller, however, Paragraph 0058 and Figure 5 indicate the presence of a controller), wherein a phase shift is introduced between the gate signal of one of the primary switches and the gate signal of a corresponding one of the secondary switches (Paragraph 0058; Figure 5).
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 teachings of Kim to incorporate the use of an EMI filter at the input and an active secondary output stage comprising switches as taught by Zhong. The EMI filter provides the benefit of suppressing high-frequency electrical noise that can cause malfunctions or damage to sensitive components. The benefit of the secondary side active output stage made up of switches instead of diodes is that with a controlled secondary side the voltage regulation is enhanced allowing for regulating the output voltage dynamically and compensating for input variations and load changes.
Regarding claim 5, Kim and Zhong teach all the limitations of claim 1. Kim further teaches a plurality of capacitors (Annotated Figure 4A Components Ca, Cb, Cc) each being connected between a corresponding input terminal of the three-phase AC power source and the neutral terminal (Annotated Figure 4A Components Ca, Cb and Cc are connected to the AC source and Component Neu).
Kim does not teach an EMI filter.
Zhong teaches an AC/DC converter (Figure 2), comprising: an AC source (Figure 2 Component Ugrid); an input stage electrically coupled to the AC power source (Figure 2 Component Diode Rectifier); an EMI filter connected to the output of the AC power source and connected between the AC power source and the input stage (Figure 2 Component EMI Filter); a switching stage including a plurality of primary switches (Figure 2 Components S1-S4); an output stage (Figure 2 Components L1, L2 and S5-S8) electrically coupled to the switching stage (Figure 2 Component L1 is coupled to Components S1-S4), the output stage including output terminals that are connectable to a load (Figure 2 Component RL), thereby providing a DC voltage to the load (Figure 2 Component Vo), wherein the output stage comprises a transformer (Figure 2 Component Transformer made up by windings L1 and L2) and an active bridge including a plurality of secondary switches (Figure 2 Components S5-S8); and a controller electrically coupled to the switching stage and the output stage to generate gate signals for the primary and secondary switches (Figure 2 does not show a controller, however, Paragraph 0058 and Figure 5 indicate the presence of a controller), wherein a phase shift is introduced between the gate signal of one of the primary switches and the gate signal of a corresponding one of the secondary switches (Paragraph 0058; Figure 5).
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 teachings of Kim to incorporate the use of an EMI filter at the input and an active secondary output stage comprising switches as taught by Zhong. The EMI filter provides the benefit of suppressing high-frequency electrical noise that can cause malfunctions or damage to sensitive components. The benefit of the secondary side active output stage made up of switches instead of diodes is that with a controlled secondary side the voltage regulation is enhanced allowing for regulating the output voltage dynamically and compensating for input variations and load changes.
Regarding claim 6, Kim and Zhong teach all the limitations of claim 1. Kim further teaches wherein the switching stage further comprises a plurality of serially connected DC-link capacitors coupled to the three-phase diode bridge in parallel (Annotated Figure 4A Components C1 and C2).
Regarding claim 7, Kim and Zhong teach all the limitations of claim 1. Kim further teaches wherein a midpoint of the DC-link capacitors (Annotated Figure 4A Components C1 and C2) is electrically coupled to one primary side terminal of the transformer (Annotated Figure 4A Component C1 and C2 have a midpoint connected to node ‘a’ which is connected to the primary winding of the transformer), while a midpoint of the primary switches is electrically coupled to another primary side terminal of the transformer (Annotated Figure 4A Components S2 and S3 have a midpoint connected to node ‘b’ which is a connected to the other terminal of the primary winding of the transformer).
Regarding claim 8, Kim and Zhong teach all the limitations of claim 1. Kim further teaches wherein the primary switches are a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT) with an antiparallel diode (Annotated Figure 4A Components S1-S4 are MOSFETs).
Kim does not teach the secondary switches.
Zhong teaches an AC/DC converter (Figure 2), comprising: an AC source (Figure 2 Component Ugrid); an input stage electrically coupled to the AC power source (Figure 2 Component Diode Rectifier); an EMI filter connected to the output of the AC power source and connected between the AC power source and the input stage (Figure 2 Component EMI Filter); a switching stage including a plurality of primary switches (Figure 2 Components S1-S4); an output stage (Figure 2 Components L1, L2 and S5-S8) electrically coupled to the switching stage (Figure 2 Component L1 is coupled to Components S1-S4), the output stage including output terminals that are connectable to a load (Figure 2 Component RL), thereby providing a DC voltage to the load (Figure 2 Component Vo), wherein the output stage comprises a transformer (Figure 2 Component Transformer made up by windings L1 and L2) and an active bridge including a plurality of secondary switches (Figure 2 Components S5-S8); and a controller electrically coupled to the switching stage and the output stage to generate gate signals for the primary and secondary switches (Figure 2 does not show a controller, however, Paragraph 0058 and Figure 5 indicate the presence of a controller), wherein a phase shift is introduced between the gate signal of one of the primary switches and the gate signal of a corresponding one of the secondary switches (Paragraph 0058; Figure 5), wherein the primary switches and secondary switches are a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT) with an antiparallel diode (Figure 2 Components S1-S4 and Components S5-S8 are MOSFETs).
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 teachings of Kim to incorporate the use of an EMI filter at the input and an active secondary output stage comprising switches as taught by Zhong. The EMI filter provides the benefit of suppressing high-frequency electrical noise that can cause malfunctions or damage to sensitive components. The benefit of the secondary side active output stage made up of switches instead of diodes is that with a controlled secondary side the voltage regulation is enhanced allowing for regulating the output voltage dynamically and compensating for input variations and load changes.
Regarding claim 10, Kim and Zhong teach all the limitations of claim 1. Kim further teaches wherein the active bridge comprises a full active bridge including four active switches or a half bridge including two active switches.
Zhong teaches an AC/DC converter (Figure 2), comprising: an AC source (Figure 2 Component Ugrid); an input stage electrically coupled to the AC power source (Figure 2 Component Diode Rectifier); an EMI filter connected to the output of the AC power source and connected between the AC power source and the input stage (Figure 2 Component EMI Filter); a switching stage including a plurality of primary switches (Figure 2 Components S1-S4); an output stage (Figure 2 Components L1, L2 and S5-S8) electrically coupled to the switching stage (Figure 2 Component L1 is coupled to Components S1-S4), the output stage including output terminals that are connectable to a load (Figure 2 Component RL), thereby providing a DC voltage to the load (Figure 2 Component Vo), wherein the output stage comprises a transformer (Figure 2 Component Transformer made up by windings L1 and L2) and an active bridge including a plurality of secondary switches (Figure 2 Components S5-S8); and a controller electrically coupled to the switching stage and the output stage to generate gate signals for the primary and secondary switches (Figure 2 does not show a controller, however, Paragraph 0058 and Figure 5 indicate the presence of a controller), wherein a phase shift is introduced between the gate signal of one of the primary switches and the gate signal of a corresponding one of the secondary switches (Paragraph 0058; Figure 5), wherein the active bridge comprises a full active bridge including four active switches or a half bridge including two active switches (Figure 2 Components S5-S8).
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 teachings of Kim to incorporate the use of an EMI filter at the input and an active secondary output stage comprising switches as taught by Zhong. The EMI filter provides the benefit of suppressing high-frequency electrical noise that can cause malfunctions or damage to sensitive components. The benefit of the secondary side active output stage made up of switches instead of diodes is that with a controlled secondary side the voltage regulation is enhanced allowing for regulating the output voltage dynamically and compensating for input variations and load changes.
Regarding claim 11, Kim and Zhong teach all the limitations of claim 1. Kim further teaches wherein the switching stage comprises first, second, third, and fourth active switches electrically coupled in series (Annotated Figure 4A Components S1-S4) and a flying capacitor (Annotated Figure 4A Component Css) electrically coupled between a midpoint between the first and second active switches (Annotated Figure 4A Component S1+S2) and a midpoint between the third and fourth active switches (Annotated Figure 4A Components S3+S4), wherein a midpoint of the second and third active switches is electrically coupled to the neutral terminal (Annotated Figure 4A Components S2 and S3 have a midpoint connected to node ‘b’ which is connected to Component Neg).
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Shahzeb K. Ahmad whose telephone number is (571)272-0978. The examiner can normally be reached Monday - Friday 8 A.M. to 5 P.M..
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/Shahzeb K Ahmad/Examiner, Art Unit 2838
/THIENVU V TRAN/ Supervisory Patent Examiner, Art Unit 2838
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