DETAILED ACTION
This Office action is in response to the application filed on 25 July 2024.
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 .
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, and 17 are rejected under 35 U.S.C. 103 as being unpatentable over Stefan Baurle et. al (US 20080084713A1; hereafter “Stefan”) in view of Richard Redl et. al (1985 IEEE Power Electronics Specialists Conference, IEEE PESC ‘85 RK., pp. 771-785; hereafter “Redl”).
-Regarding claim 17:
Stefan discloses:
A direct-current-to-direct-current (DC-to-DC) converter, comprising: a power stage including a first switching device (Fig. 4 and claim 1; “switch coupled to an energy transfer element coupled between an input and an output of the power converter”); and a controller communicatively coupled to the power stage (Fig. 4 and claim 1; “control circuit coupled to the switch to control the switch”), the controller being configured to: cause the duty cycle of the first switching device has crossed a first threshold value, and in response to the duty cycle of the first switching device crossing the first threshold value (Fig. 2 and 5; Duty cycle and claim 1; “the control circuit including first and second duty cycle control modes to regulate power delivered to the output of the power converter, wherein a transition between the first and second duty cycle control modes is responsive to a magnitude of a current flowing in the switch reaching a current threshold value”.), cause
However, Stefan does not disclose two operating modes in DC-to-DC power converter.
Redl, in the same field of endeavor, discloses:
A direct-current-to-direct-current (DC-to-DC) converter, comprising: the DC-to-DC converter to operate in a constant frequency operating mode (objective paragraph; 3rd and 5th methods in five different control methods considered), cause the DC-to-DC converter to switch from operating in the constant frequency operating mode to operating in a constant off-time operating mode (objective paragraph; 2nd method in five different control methods considered).
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 Stefan such that commonly used mode controlling methods (such as the constant frequency operating mode and the constant off time operating mode) described in Redl is applied to the mode switching device in the DC-to-DC power converter even Stefan described an AC-to-DC power converter. Doing so allows for getting a large ratio of Vout/Vin without a large inductor and large filtering components, which ensure acceptable operation at low switching frequency, and complicate efforts to achieve electromagnetic compatibility (EMC) of the DC-to-DC converter with other devices.
-Regarding claim 1:
For method claim 1, note that under MPEP 2112.02, the principles of inherency, if a prior art device, in its normal and usual operation, would necessarily perform the method claimed, then the method claimed will be considered to be anticipated by the prior art device. When the prior art is the same as a device described in the specification for carrying out the claimed method, it can be assumed the device “1 inherently performs the claimed process. In re King, 801 F.2d 1324, 231 UPSQ 136 (Fed Cir. 1986). Therefore, the previous rejections based on the apparatus will not be repeated.
Claims 2, 8, 10-13, 15, 16, 18, and 19 are rejected under 35 U.S.C. 103 as being unpatentable over Richard Redl et. al (1985 IEEE Power Electronics Specialists Conference, IEEE PESC ‘85 RK., pp. 771-785; hereafter “Redl”) in view of Stefan Baurle et. al (US 20080084713A1; hereafter “Stefan”).
-Regarding claim 10:
Redl discloses:
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A controller (Fig. 5; constant frequency controller with compensating waveform) for a direct-current-to-direct-current (DC-to-DC) converter, the controller comprisinga clock signal (Fig. 5; Clock Gen.)slope compensation module (Fig. 5; Compens. Waveform Gen.) configured to generate a slope compensation signal (Page 781; “The compensating waveform has a significant influence on the low frequency characteristics of the converter. For the most important version --peak-current-commanding-- the values of the characteristic coefficients are available. It is also known that the slope of the compensating waveform has an effect on the attenuation of perturbations: the optimum slope causes the perturbations to decay at the fastest possible rate, i.e., within one switching cycle. The optimum slope for the buck and the buck-boost topologies is constant; that means that the optimum compensating waveform is a linear ramp. For the boost converter, the optimum slope is proportional to the input voltage; hence the optimum compensating waveform is a segment of a parabola.”) at least partially based on switching control module (Fig. 5; R-S Flip flop, Comparator, and Amplifier) configured to generate a control signal to control the first switching device (Fig. 5; Vsw to power stage) at least partially based on the slope compensation signal and the clock signal;
However, Redl does not disclose the oscillator and the mode change module.
Stefan, in the same field of endeavor, discloses:
an oscillator (Fig. 6A) configured to generate an oscillator signal, a duty cycle signal, the duty cycle signal (Fig. 2; Duty cycle) indicating that a maximum permissible duty cycle (Fig. 2 and 5; Maximum Duty Cycle and Peak Switch Current) of a first switching device of the DC-to-DC converter has been exceededa mode change module (Fig. 7; logic circuit inside control circuit) configured to change operation of each of the oscillator
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 Redl such that a commonly used controlling method for the circuit with multiple operating modes described in Stefan is applied to the constant frequency controller with compensating waveform and with valley current command. Doing so allows for getting an effective mode changing in the controller for the DC-to-DC converter.
-Regarding claim 2:
Stefan discloses:
The method of claim 1, wherein the first threshold value is a maximum permissible duty cycle of the first switching device (Fig. 2; Maximum Duty Cycle 217 and Peak switch Current 205) of the DC-to-DC converter in the constant frequency operating mode of the DC-to-DC converter.
-Regarding claim 8:
Redl discloses:
The method of claim 1, further comprising causing the first switching device to operate in its off-state (Fig. 5; turn-off at clock time), in response to magnitude of current flowing (Fig. 5; iL) through an inductor of the DC-to-DC converter reaching a second threshold value (Fig. 5; IL vs time graph).
-Regarding claim 11:
Redl discloses:
The controller of claim 10, wherein the switching control module is further configured to generate the control signal at least partially based on an error signal (page 778; “The controlled variable (x) is the variable which is controlled by the error amplifier.”)
-Regarding claim 12:
Redl discloses:
The controller of claim 11, further comprising a voltage control module configured to generate the error signal at least partially based on a difference between a voltage of the DC-to-DC converter and a reference voltage (page 779; Eq. 16).
-Regarding claim 13:
Redl discloses:
The controller of claim 10, wherein the switching control module is further configured to generate the control signal based on a magnitude of current flowing through an inductor (Fig. 5; iL) of the DC-to-DC converter.
-Regarding claim 15:
Redl discloses:
The controller of claim 10, wherein the oscillator is configured such that the DC-to-DC converter switches from a constant frequency operating mode to a constant off-time operating mode (objective paragraph; 2nd, 3rd, and 5th methods in five different control methods considered) in response to assertion of the duty cycle signal.
-Regarding claim 16:
Stefan discloses:
The controller of claim 10, wherein the oscillator (Fig. 6A) is configured such that a switching frequency of the DC-to-DC converter is reduced in response to assertion of the duty cycle signal (Fig. 2 and 5).
-Regarding claim 18:
Stefan discloses:
The DC-to-DC converter of claim 17, wherein the first threshold value (Fig. 2; peak switch current 216) is a maximum permissible duty cycle (Fig. 2; maximum duty cycle 217) of the first switching device, in the constant frequency operating mode (Fig. 2; switching frequency 218).
-Regarding claim 19:
Redl discloses:
The DC-to-DC converter of claim 17, wherein the power stage has a topology selected from the group consisting of a boost topology, a buck-boost topology, and a buck topology (page 776; table 3 and 4).
Allowable Subject Matter
Claims 3-7, 9, 14, and 20 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 3:
the prior arts in Stefan, and Redl disclose the claimed invention in basic claims but do not further disclose about a causing the DC-to-DC converter to operate in the constant off-time operating mode comprises changing operation of an oscillator.
-with respect to claim 6:
the prior arts in Stefan, and Redl disclose the claimed invention in basic claims but do not further disclose about a changing operation of a slope compensation module.
-Regarding claim 9:
the prior arts in Stefan, and Redl disclose the claimed invention in basic claims but do not further disclose about the constant frequency operating mode for an entirety of the second switching cycle of the DC-to-DC converter, in response to the duty cycle of the first switching of the DC-to-DC converter not exceeding the first threshold value before the first switching device of the DC-to-DC converter switches to its off-state.
-Regarding claim 14:
the prior arts in Stefan, and Redl disclose the claimed invention in basic claims but do not further disclose about a maximum permissible duty cycle of the first switching device in a constant frequency operating mode
-Regarding claim 20:
the prior arts in Stefan, and Redl disclose the claimed invention in basic claims but do not further disclose about the changing operation of the oscillator.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
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