DETAILED ACTION
Response to Arguments
Applicant’s arguments with respect to the claims have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
Claim Objections
Claims 1-2, 4-16, & 19 are objected to because of the following informalities:
Claim 1 recites the limitation “the first terminal" in line 5. There is insufficient antecedent basis for this limitation in the claim due to there being multiple bidirectional switches. It is unclear whether this limitation applies to a particular bidirectional switch or all of the bidirectional switches.
Claim 1 recites the limitation “the second terminal" in line 5-6. There is insufficient antecedent basis for this limitation in the claim due to there being multiple bidirectional switches. It is unclear whether this limitation applies to a particular bidirectional switch or all of the bidirectional switches.
Claim 1 recites the limitation “the first silicon carbide transistor" in line 7. There is insufficient antecedent basis for this limitation in the claim due to there being multiple bidirectional switches. It is unclear whether this limitation applies to a particular bidirectional switch or all of the bidirectional switches.
Claim 1 recites the limitation “the second silicon carbide transistor" in line 15. There is insufficient antecedent basis for this limitation in the claim due to there being multiple bidirectional switches. It is unclear whether this limitation applies to a particular bidirectional switch or all of the bidirectional switches.
Claim 1 recites the limitation “the first diode" in line 13. There is insufficient antecedent basis for this limitation in the claim due to there being multiple bidirectional switches. It is unclear whether this limitation applies to a particular bidirectional switch or all of the bidirectional switches.
Claim 1 recites the limitation “the second diode" in line 23. There is insufficient antecedent basis for this limitation in the claim due to there being multiple bidirectional switches. It is unclear whether this limitation applies to a particular bidirectional switch or all of the bidirectional switches.
Claims 2, 4-16, & 19 depend from Claim 1 and thus have at least the same defects.
Appropriate correction is required.
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 (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.
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 1-2, 4, 7-8, 10-13 and 16-17 are rejected under 35 U.S.C. 103 as being unpatentable over Yamazaki (US 20150130431 A1) in view of Kyoken (JP 2017077096 A) and further in view of Xia (CN 211236190 U).
Regarding Claim 1, Yamazaki teaches a power conversion apparatus (see Figs 1 & 2) comprising multiple bidirectional switches (Sru, Ssu, Stu, Srv, Ssv, Stv, Srw, Ssw, & Stw, Fig 1 & 2), wherein each of the multiple bidirectional switches (Sw, Fig 2) has: a first terminal (Vi, Fig 2) and a second terminal (Vo, Fig 2); a first silicon carbide transistor (Swa, Fig 2, [0037]) provided between the first terminal and the second terminal (Swa is between Vi and Vo, Fig 2); a first diode which is provided in series with the first silicon carbide transistor between the first terminal and the second terminal (Da is in series with Swa between Vi and Vo, Fig 2), of which a forward direction is a direction directed from the first terminal toward the second terminal (forward bias of Da is from Vi to Vo, Fig 2), among the multiple bidirectional switches (Sru, Ssu, Stu, Srv, Ssv, Stv, Srw, Ssw, & Stw, Fig 1); a second silicon carbide transistor (Swb is a SiC transistor, Fig 2, [0037]) provided in parallel with the first diode between the first terminal and the second terminal (Swb is in parallel with Da and is connected between Vi and Vo, Fig 2); a second diode which is provided in series with the second silicon carbide transistor (Db is in series with Swb, Fig 2) and in parallel with the first silicon carbide transistor between the first terminal and the second terminal (Db is in parallel with Swa between Vi and Vo, Fig 2), of which a forward direction is a direction directed from the second terminal toward the first terminal (forward bias of Db is from Vo to Vi, Fig 2), and a connection line (vertical line between the node connecting Swa & Da and the node connecting Swb & Db, Fig 2) which connects a first connection point between the first silicon carbide transistor and the first diode (the node connecting Swa & Da, Fig 2), and a second connection point between the second silicon carbide transistor and the second diode (the node connecting Swb & Db, Fig 2).
Yamazaki does not teach a first diode of which on voltage is lower than on voltage of a built-in diode of the first silicon carbide transistor at a rated current of the bidirectional switch, and a second diode of which on voltage is lower than on voltage of a built-in diode of the second silicon carbide transistor at the rated current of the bidirectional switch; and a breakdown voltage of the first diode is higher than a breakdown voltage of the first silicon carbide transistor.
Kyoken teaches a conventional power conversion apparatus with a bidirectional switch (20, Fig 2) comprising: a first terminal (a drain side terminal of a switching element 7, Fig 2) and a second terminal (a drain side terminal of a switching element 8, Fig 2); a first silicon carbide transistor (7 is a SiC transistor, Fig 2, [0016]) provided between the first terminal and the second terminal (7 is between its drain side and the drain side of 8, Fig 2); a first diode which is provided in series with the first silicon carbide transistor between the first terminal and the second terminal (8a' is in series with 7 between 7's drain terminal and the drain side of 8, Fig 2), of which a forward direction is a direction directed from the first terminal toward the second terminal (forward is from the drain side of 7 toward the drain side of 8, Fig 2), and of which on voltage is lower than on voltage of a built-in diode of the first silicon carbide transistor at a rated current of a corresponding bidirectional switch (a reflux diode 8a′ made of a silicon-based semiconductor material having an ON resistance characteristic lower than that of a parasitic diode 8a; the ON voltage at the rated current is naturally lower if the ON resistance characteristic is low, [0021]), a second silicon carbide transistor (8 is a SiC transistor, Fig 2, [0016]) provided in parallel with the first diode between the first terminal and the second terminal (8 is in parallel with 8a' and is connected between the drain sides of 7 & 8, Fig 2); a second diode which is provided in series with the second silicon carbide transistor (7a' is in series with 8 between the drain terminals of 7 & 8, Fig 2), and in parallel with the first silicon carbide transistor between the first terminal and the second terminal (7a' is in parallel with 7 between the drain terminals of 7 & 8, Fig 2), of which a forward direction is a direction directed from the second terminal toward the first terminal (forward is from the drain side of 7 toward the drain side of 8, Fig 2), and of which on voltage is lower than on voltage of a built-in diode of the second silicon carbide transistor at the rated current of the corresponding bidirectional switch (a reflux diode 7a′ made of a silicon-based semiconductor material having an ON resistance characteristic lower than that of a parasitic diode 7a; the ON voltage at the rated current is naturally lower if the ON resistance characteristic is low, [0021]); and a connection line (line between source side nodes of 7 & 8, Fig 2) which connects a first connection point between the first silicon carbide transistor and the first diode (the node connected to the source side of 7 is connected to the cathode of 8a', Fig 2), and a second connection point between the second silicon carbide transistor and the second diode (the node connected to the source side of 8 is connected to the cathode of 7a', Fig 2).
Kyoken doesn’t teach a breakdown voltage of the first diode is higher than a breakdown voltage of the first silicon carbide transistor.
Xia teaches a conventional bidirectional switch (see Fig 2), including a breakdown voltage of the first diode ("diode is a diode withstand voltage of 2000V", d2, Fig 2, pg3, paragraph 10) is higher than a breakdown voltage of the first silicon carbide transistor ("the MOSFET is MOSFET with withstand voltage of 1000-1500V", q1, Fig 2, pg3, paragraph 10).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have optionally included the bidirectional switch in Yamazaki, as taught by Kyoken, as it provides the advantage of improving the efficiency of the converter by reducing conduction loss ("by using silicon diodes having lower on-resistance characteristics than the parasitic diodes 7a and 8a as the freewheeling diodes 7a 'and 8a', the conduction loss can be reduced", -abstract & [0025] of Kyoken).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have optionally included the bidirectional switch in Yamazaki, as taught by Xia, as it provides the advantage of optimizing the breakdown voltage design to ensure that the transistor governs avalanche behavior.
Regarding Claim 2, the combination of Yamazaki, Kyoken, and Xia teaches all of the claim limitations of claim 1, and further teaches wherein the first diode and the second diode are silicon diodes having P-N junctions (diodes 7a′ and 8a' are made of a silicon-based semiconductor material and standard diodes have P-N junctions, [0021] of Kyoken).
Regarding Claim 4, the combination of Yamazaki, Kyoken, and Xia teaches all of the claim limitations of claim 1, and further teaches wherein a breakdown voltage of the second diode ("diode is a diode withstand voltage of 2000V", d1, Fig 2, pg3, paragraph 10 of Xia) is higher than a breakdown voltage of the second silicon carbide transistor ("the MOSFET is MOSFET with withstand voltage of 1000-1500V", q2, Fig 2, pg3, paragraph 10 of Xia).
Regarding Claim 7, the combination of Yamazaki, Kyoken, and Xia teaches all of the limitations of claim 1, and further teaches further comprising a control unit (Controller 14, Fig 1 of Yamazaki).which controls, when turning on the corresponding bidirectional switch, both of the first silicon carbide transistor and the second silicon carbide transistor to be turned on (Sw2p corresponding to Swa and Sw2n corresponding to Swb are both on at t4, left timing diagram of Fig 6, [0065] of Yamazaki)).
Regarding Claim 8, the combination of Yamazaki, Kyoken, and Xia teaches all of the limitations of claim 7, and further teaches wherein when the corresponding bidirectional switch is turned on, current that flows in the first diode is smaller than current that flows in the second silicon carbide transistor (since the on-resistance of the silicon carbide transistor is lower than the on-resistance of the diode of the silicon P-N junction, the current flowing through the first diode becomes smaller than the current flowing through the second silicon carbide transistor, Fig 2 of Kyoken).
Regarding Claim 10, the combination of Yamazaki, Kyoken, and Xia teaches all of the limitations of claim 7, and further teaches wherein: the multiple bidirectional switches include a first bidirectional switch (Sw1p corresponding to Swa and Sw1n corresponding to Swb, both located in the first bidirectional switch Fig 10, [0065] of Yamazaki)) and a second bidirectional switch (Sw2p corresponding to Swa and Sw2n corresponding to Swb, both located in the second bidirectional switch, Fig 10, [0065] of Yamazaki)) ; and the control unit (Controller 14, Fig 1 of Yamazaki) causes, when commutating current from the first bidirectional switch to the second bidirectional switch, the first silicon carbide transistor of the second bidirectional switch to transition to an on state at a first timing (Sw2p corresponding to Swa of second bidirectional switch turns ON at t1, left timing diagram of Fig 10, of Yamazaki)).
Regarding Claim 11, the combination of Yamazaki, Kyoken, and Xia teaches all of the limitations of claim 10, and further teaches wherein the control unit (Controller 14, Fig 1 of Yamazaki) causes the first silicon carbide transistor of the first bidirectional switch to transition to an off state at a second timing that comes after the first timing (Sw1p corresponding to Swa of first bidirectional switch turns OFF at t2 after t1, left timing diagram of Fig 10, of Yamazaki)).
Regarding Claim 12, the combination of Yamazaki, Kyoken, and Xia teaches all of the limitations of claim 11, and further teaches wherein the control unit (Controller 14, Fig 1 of Yamazaki) causes the second silicon carbide transistor of the second bidirectional switch to transition to an on state at a third timing that comes after the second timing (Sw2n corresponding to Swb of second bidirectional switch turns ON at t3 after t2, left timing diagram of Fig 10, of Yamazaki)).
Regarding Claim 13, the combination of Yamazaki, Kyoken, and Xia teaches all of the limitations of claim 12, and further teaches wherein the control unit (Controller 14, Fig 1 of Yamazaki) causes the second silicon carbide transistor of the first bidirectional switch to transition to an off state at a fourth timing that comes after the third timing (Sw1n corresponding to Swb of first bidirectional switch turns OFF at t3 after t2, left timing diagram of Fig 10, of Yamazaki)).
Regarding Claim 16, the combination of Yamazaki, Kyoken, and Xia teaches all of the limitations of claim 12, and further teaches wherein the control unit causes the second silicon carbide transistor of the first bidirectional switch to transition to an off state at a fourth timing that comes before the third timing (Sw1n corresponding to Swb of first bidirectional switch turns OFF at t1 before t3 where sw2n turns ON, left timing diagram of Fig 6, of Yamazaki)).
Regarding Claim 17, Yamazaki teaches a bidirectional switch (see Fig 2), comprising: a first terminal (Vi, Fig 2) and a second terminal (Vo, Fig 2); a first silicon carbide transistor (Swa, Fig 2, [0037]) provided between the first terminal and the second terminal (Swa is between Vi and Vo, Fig 2); a first diode which is provided in series with the first silicon carbide transistor between the first terminal and the second terminal (Da is in series with Swa between Vi and Vo, Fig 2), of which a forward direction is a direction directed from the first terminal toward the second terminal (forward bias of Da is from Vi to Vo, Fig 2), a second silicon carbide transistor (Swb is a SiC transistor, Fig 2, [0037]) provided in parallel with the first diode between the first terminal and the second terminal (Swb is in parallel with Da and is connected between Vi and Vo, Fig 2); a second diode which is provided in series with the second silicon carbide transistor (Db is in series with Swb, Fig 2) and in parallel with the first silicon carbide transistor between the first terminal and the second terminal (Db is in parallel with Swa between Vi and Vo, Fig 2), of which a forward direction is a direction directed from the second terminal toward the first terminal (forward bias of Db is from Vo to Vi, Fig 2), and a connection line (vertical line between the node connecting Swa & Da and the node connecting Swb & Db, Fig 2) which connects a first connection point between the first silicon carbide transistor and the first diode (the node connecting Swa & Da, Fig 2), and a second connection point between the second silicon carbide transistor and the second diode (the node connecting Swb & Db, Fig 2).
Yamazaki does not teach a first diode of which on voltage is lower than on voltage of a built-in diode of the first silicon carbide transistor at a rated current of the bidirectional switch, and a second diode of which on voltage is lower than on voltage of a built-in diode of the second silicon carbide transistor at the rated current of the bidirectional switch; and a breakdown voltage of the first diode is higher than a breakdown voltage of the first silicon carbide transistor.
Kyoken teaches a conventional bidirectional switch (20, Fig 2) comprising: a first terminal (a drain side terminal of a switching element 7, Fig 2) and a second terminal (a drain side terminal of a switching element 8, Fig 2); a first silicon carbide transistor (7 is a SiC transistor, Fig 2, [0016]) provided between the first terminal and the second terminal (7 is between its drain side and the drain side of 8, Fig 2); a first diode which is provided in series with the first silicon carbide transistor between the first terminal and the second terminal (8a' is in series with 7 between 7's drain terminal and the drain side of 8, Fig 2), of which a forward direction is a direction directed from the first terminal toward the second terminal (forward is from the drain side of 7 toward the drain side of 8, Fig 2), and of which on voltage is lower than on voltage of a built-in diode of the first silicon carbide transistor at a rated current of a corresponding bidirectional switch (a reflux diode 8a′ made of a silicon-based semiconductor material having an ON resistance characteristic lower than that of a parasitic diode 8a; the ON voltage at the rated current is naturally lower if the ON resistance characteristic is low, [0021]), a second silicon carbide transistor (8 is a SiC transistor, Fig 2, [0016]) provided in parallel with the first diode between the first terminal and the second terminal (8 is in parallel with 8a' and is connected between the drain sides of 7 & 8, Fig 2); a second diode which is provided in series with the second silicon carbide transistor (7a' is in series with 8 between the drain terminals of 7 & 8, Fig 2), and in parallel with the first silicon carbide transistor between the first terminal and the second terminal (7a' is in parallel with 7 between the drain terminals of 7 & 8, Fig 2), of which a forward direction is a direction directed from the second terminal toward the first terminal (forward is from the drain side of 7 toward the drain side of 8, Fig 2), and of which on voltage is lower than on voltage of a built-in diode of the second silicon carbide transistor at the rated current of the corresponding bidirectional switch (a reflux diode 7a′ made of a silicon-based semiconductor material having an ON resistance characteristic lower than that of a parasitic diode 7a; the ON voltage at the rated current is naturally lower if the ON resistance characteristic is low, [0021]).
Kyoken doesn’t teach a breakdown voltage of the first diode is higher than a breakdown voltage of the first silicon carbide transistor.
Xia teaches a conventional bidirectional switch (see Fig 2), including a breakdown voltage of the first diode ("diode is a diode withstand voltage of 2000V", d2, Fig 2, pg3, paragraph 10) is higher than a breakdown voltage of the first silicon carbide transistor ("the MOSFET is MOSFET with withstand voltage of 1000-1500V", q1, Fig 2, pg3, paragraph 10).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have optionally included the bidirectional switch in Yamazaki, as taught by Kyoken, as it provides the advantage of improving the efficiency of the converter by reducing conduction loss ("by using silicon diodes having lower on-resistance characteristics than the parasitic diodes 7a and 8a as the freewheeling diodes 7a 'and 8a', the conduction loss can be reduced", -abstract & [0025] of Kyoken).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have optionally included the bidirectional switch in Yamazaki, as taught by Xia, as it provides the advantage of optimizing the breakdown voltage design to ensure that the transistor governs avalanche behavior.
Claims 5-6 are rejected under 35 U.S.C. 103 as being unpatentable over Yamazaki (US 20150130431 A1) in view of Kyoken (JP 2017077096 A) and Xia (CN 211236190 U), and further in view of Masuda (JP 2017183957 A).
Regarding Claim 5, the combination of Yamazaki, Kyoken, and Xia teaches all of the claim limitations of claim 1, and further teaches the first diode (start-up voltage of 8a', Fig 2 of Kyoken), built-in diode (start-up voltage of 8a, Fig 2 of Kyoken).
The combination of Yamazaki, Kyoken, and Xia does not teach wherein a start-up voltage of the first diode is lower than a start-up voltage of the built-in diode of the second silicon carbide transistor.
Masuda teaches a conventional bidirectional switch (see Fig 2a) wherein a start-up voltage of the first diode is lower than a start-up voltage of the built-in diode of the second silicon carbide transistor (the SiC-MOSFET is connected in parallel to the SiC diode, and therefore, by turning on the SiC-MOSFET, the current is divided into the SiC-MOSFET and the SiC diode, and therefore, the forward voltage drop (VF) of the SiC diode can be reduced compared to when the SiC-MOSFET is not turned on.", (, Fig 2a), [0018]).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have optionally included the bidirectional switch in Yamazaki, as taught by Masuda, as it provides the advantage of reducing the cost of the system by reducing the size of a bidirectional switch module (abstract of Masuda).
Regarding Claim 6, the combination of Yamazaki, Kyoken, and Xia and Masuda teaches all of the claim limitations of claim 5, and further teaches wherein a start-up voltage of the second diode (start-up voltage of 7a', Fig 2 of Kyoken) is lower than a start-up voltage of the built-in diode (start-up voltage of 7a, Fig 2 of Kyoken) of the first silicon carbide transistor (the SiC-MOSFET is connected in parallel to the SiC diode, and therefore, by turning on the SiC-MOSFET, the current is divided into the SiC-MOSFET and the SiC diode, and therefore, the forward voltage drop (VF) of the SiC diode can be reduced compared to when the SiC-MOSFET is not turned on.", (, Fig 2a), [0018] of Masuda).
Regarding Claim 19, it is rejected for the same reasons as stated above for Claim 5.
Allowable Subject Matter
Claims 9 & 14-15 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 and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter:
Regarding claim 9, the combination of Yamazaki, Kyoken, and Xia teaches all of the limitations of claim 8.
The combination of Yamazaki, Kyoken, and Xia does not teach, “when the corresponding bidirectional switch is turned on, the current that flows in the first diode is equal to or less than 10% of the current that flows in the second silicon carbide transistor.”
Prior art Masuda (JP 2017183957 A) and Xia (CN 211236190 U) are considered to be the closest prior art.
However, none of the prior art, taken singly or in combination, teach “wherein when the corresponding bidirectional switch is turned on, the current that flows in the first diode is equal to or less than 10% of the current that flows in the second silicon carbide transistor.”
Regarding claim 14, the combination of Yamazaki, Kyoken, and Xia teaches all of the limitations of claim 1.
The combination of Yamazaki, Kyoken, and Xia does not teach, “wherein in the first diode and the second diode, carrier lifetime of holes is equal to or more than 1 μs when the first diode and the second diode are turned off.”
Prior art Masuda (JP 2017183957 A) and Xia (CN 211236190 U) are considered to be the closest prior art.
However, none of the prior art, taken singly or in combination, teach “wherein in the first diode and the second diode, carrier lifetime of holes is equal to or more than 1 μs when the first diode and the second diode are turned off.”
Regarding claim 15, the combination of Yamazaki, Kyoken, and Xia teaches all of the limitations of claim 12.
The combination of Yamazaki, Kyoken, and Xia does not teach, “wherein the control unit simultaneously causes the second silicon carbide transistor of the first bidirectional switch to transition to an off state at the third timing.”
Prior art Masuda (JP 2017183957 A) and Xia (CN 211236190 U) are considered to be the closest prior art.
However, none of the prior art, taken singly or in combination, teach “wherein the control unit simultaneously causes the second silicon carbide transistor of the first bidirectional switch to transition to an off state at the third timing.”
Conclusion
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/J.C.C./Examiner, Art Unit 2838
/GARY L LAXTON/Primary Examiner, Art Unit 2838 4/09/2026
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