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 .
Allowable Subject Matter
Claims 12 and 13 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.
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) 1-5, 7- 11 and 14, 16-17 are rejected under 35 U.S.C. 103 as being unpatentable over Wang et al. (US 2023/0170711) in view of Zhang et al. (US 2024/0364206)
Re Claims 1 and 14; Wang discloses
An energy storage system, comprising: Wang discloses an energy storage system including batteries, power converters, DC buses, and grid/load interfaces, as shown in Fig. 1 and described in paragraphs [0005] and [0010], which explicitly describe an “energy storage system” for storing and converting electric energy.
an energy storage converter having an AC end electrically connected to an AC power supply or a load, and a DC end electrically connected to a DC bus;
Wang teaches an energy storage converter labeled “DC/AC” having an AC side connected to a grid or load and a DC side connected to a DC bus, as illustrated in Fig. 1 and Fig. 4 and described in paragraphs [0005], [0035], and [0036]. The DC bus is explicitly identified as the common DC-side connection for the system.
at least one battery unit, each electrically connected to the DC bus through a DC/DC converter;
Wang discloses multiple battery modules and battery clusters (e.g., battery clusters 140 and 240) electrically connected to a DC bus through respective DC/DC converters 410 and 420, as shown in Fig. 4 and described in paragraphs [0035]–[0037]. Each battery unit interfaces with the DC bus via a DC/DC converter rather than being directly connected.
a start unit (soft start circuit) electrically connected between a battery unit and the DC bus;”
Wang discloses startup circuitry located electrically between the battery cluster and the DC-side circuitry, including a precharge resistor R1, switch K1, and capacitor Cin, as shown in Fig. 7 and described in paragraph [0046, 7]. This circuitry is positioned electrically between the battery unit and the DC bus path and operates during system startup.
wherein when the energy storage system starts through the battery unit, the start unit establishes a bus voltage to a set voltage through power of the battery unit.”
Wang teaches that when the system starts using battery power, battery energy is delivered through startup circuitry to charge DC-side capacitors and raise the DC bus voltage prior to normal operation, as shown in Fig. 7 and Fig. 8 and described in paragraph [0047]. Fig. 8 explicitly illustrates a controlled, gradual voltage rise during startup.
Wang does not expressly use the phrase “set voltage.” and wherein after the start unit establishes the bus voltage to the set voltage, the at least one DC/DC converter operates to establish the bus voltage from the set voltage to a target voltage through power of the battery unit..
However, Zhang expressly teaches establishing a controlled voltage threshold during soft-start.
Zhang teaches wherein after the start unit establishes the bus voltage to the set voltage, the at least one DC/DC converter operates to establish the bus voltage from the set voltage to a target voltage through power of the battery unit. [0008] and [0049].
It would have been obvious to a person of ordinary skill in the art to view Wang’s precharge voltage level as a “set voltage,” and further to implement Zhang’s explicit soft-start control to define and regulate that set voltage, because both references disclose controlled voltage establishment during battery-initiated startup for the same purpose of preventing sudden voltage changes and protecting system components.
Re Claim 2; Wang discloses wherein the start unit comprises: a start circuit having an input end electrically connected to the battery unit (420); and a switching circuit (K1) having one end electrically connected to an output end of the start circuit, and the other end electrically connected to the DC bus. (Fig. 7)
Re Claim 3; Zhang discloses wherein, the set voltage is a voltage of the battery unit; and the switching circuit is a diode having an anode electrically connected to a positive output end of the start circuit, and a cathode electrically connected to the DC bus. (Fig. 3 [0048])
Re Claim 4; Wang discloses wherein, when the bus voltage is less than the set voltage, the switching circuit is conducted, and the start circuit outputs power to the DC bus;
Wang teaches that startup circuitry conducts when DC-side voltage is low to charge DC-side capacitors, as shown in Fig. 7 and Fig. 8.]
Wang does not explicitly describe conduction based on comparison to a set voltage
Zhang teaches voltage-comparison-based startup behavior where the soft-start circuit supplies power until a threshold voltage is reached, as described in paragraph [0048].
Voltage-threshold-based conduction is a standard control strategy that Zhang explicitly teaches.
and when the bus voltage is greater than the set voltage, the switching circuit is off, and the start circuit stops outputting electric power to the DC bus.
Wang teaches disconnecting or bypassing startup circuitry once DC-side voltage reaches operational levels, as shown in Fig. 8.]
Therefore, it would have been obvious to one of the ordinary skilled in the art before the effective filing of the invention to have automatically disabling the start unit at a threshold voltage is a predictable and desirable safety feature.
Re Claim 5; Zhang teaches wherein, the set voltage is a voltage of the battery unit; and the switching circuit is a diode having an anode electrically connected to a positive output end of the start circuit, and a cathode electrically connected to the DC bus. (Fig. 3)
Re Claim 7; Zhang teaches comprising a battery management unit electrically connected to the start unit and the DC/DC converter; when the energy storage system starts through the battery unit, the battery management unit outputs a start command to the start unit, and the start unit operates; and when the start circuit establishes the bus voltage to the set voltage, the battery management unit outputs a control signal to the DC/DC converter, and the DC/DC converter operates. [0045], [0049]
Re Claim 8; Zhang teaches the start circuit is a precharge circuit, and comprises a precharge resistor, a precharge switch and a main switch. (Fig. 3)
Re Claim 9; Wang teaches controlled startup of a DC bus using switching elements that regulate the delivery of battery power during startup. As shown in Fig. 8 and described in paragraph [0047], Wang discloses gradually increasing DC-side voltage using controlled switching behavior. Paragraphs [0039] and [0048] further disclose that switching devices are controlled to regulate voltage and current during startup and normal operation.
Wang does not explicitly disclose that the start circuit is a “buck circuit,” nor does Wang explicitly disclose PWM modulation of a controllable switch within the start circuit.
Zhang explicitly discloses a soft-start circuit implemented using a DC/DC conversion topology in which controllable switches are driven using PWM control to regulate voltage rise during startup. Paragraphs [0007], [0045], and [0048] describe PWM-controlled switching to gradually control output voltage during soft-start, which constitutes a buck-type operation when reducing or regulating voltage from the battery to the DC-side circuitry.
It would have been obvious to a person of ordinary skill in the art to implement Wang’s startup circuitry using Zhang’s PWM-controlled buck-type soft-start circuit, because PWM-controlled buck converters are a well-known and predictable way to regulate startup voltage, limit inrush current, and achieve controlled DC bus charging. The substitution yields predictable results and directly addresses the same startup control problem identified in Wang.
Re Claim 10; the combination of Wang in view of Zhang discloses wherein an output voltage of the buck circuit is gradually increased by controlling a duty ratio of the at least one controllable switch, such that the bus voltage is gradually increased from zero to the set voltage.”
Wang teaches that during startup the DC bus voltage increases gradually rather than instantaneously, as shown in Fig. 8, which illustrates a ramped voltage profile, and described in paragraph [0047]. This demonstrates gradual voltage establishment during startup.
Wang does not explicitly disclose that the gradual voltage increase is achieved by controlling a duty ratio of a controllable switch, nor does Wang explicitly disclose PWM duty-ratio control.]
Zhang expressly teaches controlling the duty ratio of PWM-driven switches during soft-start so that the output voltage gradually rises from zero to a predetermined voltage level. Paragraphs [0007] and [0048] explicitly describe gradual voltage increase achieved by adjusting duty ratios of controllable switches.
It would have been obvious to apply Zhang’s explicit PWM duty-ratio control technique to Wang’s startup process in order to implement the gradual voltage increase already desired by Wang, because PWM duty control is a standard, well-understood method for achieving smooth voltage ramping in DC/DC converters.
Re Claim 11; the combination of Wang in view of Zhang discloses wherein the set voltage is equal to the voltage of the battery unit, the switching circuit is a diode, and when the bus voltage is greater than the voltage of the battery unit, the diode is reversely cut off.”
Wang teaches isolating circuits and preventing reverse current flow using semiconductor devices once DC-side voltage exceeds battery-side voltage, as described in paragraphs [0039] and [0046]. Wang’s startup circuitry is disengaged once normal operation begins, inherently preventing reverse current.
Wang does not explicitly disclose that the switching circuit is a diode, nor does Wang explicitly state that the diode is reversely cut off when bus voltage exceeds battery voltage.
Zhang discloses the use of diodes in startup and DC/DC paths to control current direction and prevent reverse current flow once voltage thresholds are exceeded, as shown in Fig. 3 and described in paragraph [0048]. Zhang teaches that when the downstream voltage exceeds the upstream source voltage, the diode becomes reverse-biased and stops conduction.
Replacing or supplementing Wang’s switching elements with a diode as taught by Zhang is an obvious design choice, because diodes are a well-known equivalent for preventing reverse current during startup and shutdown. The behavior of reverse cutoff when bus voltage exceeds battery voltage is an inherent and predictable property of diodes.
Re Claim 15; the combination of Wang in view of Zhang discloses wherein when the bus voltage is established to the set voltage, operate the DC/DC converter to deliver the power of the battery unit to the DC bus, thereby establishing the bus voltage from the set voltage to a target voltage.”
Wang explicitly teaches that after startup/precharge, the DC/DC converters begin normal operation to regulate and raise the DC bus voltage to its operating level, as described in paragraphs [0048] and [0050] and illustrated in Fig. 8.]
Wang does not explicitly describe the transition in terms of “set voltage” and “target voltage.”]
Zhang teaches transitioning from soft-start voltage control to normal DC/DC operation once a threshold voltage is reached, as described in paragraphs [0008] and [0049].
The staged transition from startup voltage to operating voltage is a standard and predictable sequence, explicitly taught by Zhang.
Re Claim 16; the combination of Wang in view of Zhang discloses wherein when the DC/DC converter operates and the bus voltage is greater than the set voltage, the start unit is turned off.”
Wang teaches disabling or bypassing startup circuitry once normal DC/DC operation begins, as shown in Fig. 8 and described in paragraph [0048], thereby preventing further startup current flow.
Wang does not explicitly describe a conditional step of turning off the start unit based on comparison to a set voltage.
Zhang explicitly teaches disabling the soft-start circuit once the voltage exceeds a predetermined threshold, as described in paragraph [0048].
Therefore, it would have been obvious to one of the ordinary skilled in the art to automatically turning off the start unit after startup completion is a predictable safety and efficiency measure explicitly taught by Zhang.
Re Claim 17; Wang discloses monitoring system conditions and controlling startup behavior via a controller, as described in paragraphs [0038]–[0042].
Wang does not explicitly frame these control actions as separate method steps.
Zhang teaches controller-based decision-making and command issuance during startup, as described in paragraphs [0045] and [0049].
Therefore, it would have been obvious to one of the ordinary skilled in the art to have a Controller-driven startup sequencing since it is standard practice.
Response to Arguments
Applicant's arguments filed 06/14/2026 have been fully considered but they are not persuasive.
Applicant argues that neither Wang nor Zhang discloses the amended claim 1 requirement of:
“a start unit electrically connected between a battery unit and the DC bus; wherein when the energy storage system starts through the battery unit, the start unit establishes a bus voltage to a set voltage through power of the battery unit, after the start unit establishes the bus voltage to the set voltage, the at least one DC/DC converter operates to establish the bus voltage from the set voltage to a target voltage…”
Applicant further contends that in Zhang, both the soft-start circuit and the DC/DC converter operate simultaneously during startup, and therefore Zhang does not teach a staged process where (1) a start unit first establishes a set voltage and only afterward (2) the DC/DC converter boosts the bus to a target voltage. Applicant cites Zhang ¶[0008]–[0049] and asserts that Zhang’s soft-start circuit always operates in conjunction with the DC/DC converter, not sequentially. Applicant concludes that the combination of Wang and Zhang fails to teach or suggest the claimed staged-voltage establishment.
Examiner respectfully disagrees.
After carefully reviewing Applicant’s remarks and the cited portions of Wang and Zhang, the Examiner respectfully maintains that the combination still teaches or renders obvious the amended claim 1.
1. Zhang explicitly teaches a dedicated soft-start unit that establishes an initial bus voltage before normal DC/DC operation.
Applicant’s argument overlooks that Zhang does disclose a structure that performs the same functional role as the claimed “start unit.”
Zhang describes a soft-start circuit comprising a first branch and a second branch, connected between the DC/DC converter and the power converter. During startup, Zhang explains:
“When the energy storage apparatus is started normally… the second end of the DC/DC conversion circuit outputs electric energy… the controller controls the second switch to be turned on, so that the second branch is connected… the voltage at the first end of the power converter does not suddenly increase.” —Zhang ¶[0008]
This soft-start branch is electrically between the battery/DC/DC output and the DC bus, and its purpose is to establish a controlled initial bus voltage which corresponds to the claimed “set voltage.”
Zhang further states:
“When… the voltage at the first end of the power converter [becomes] close to the voltage at the second end of the DC/DC conversion circuit, it indicates that the soft-start succeeds. In this case, the controller… turns off the second switch and turns on the first switch… and the entire system works normally.” Zhang ¶[0008]
This is a two-stage startup, exactly the type Applicant claims:
Soft-start branch establishes the initial bus voltage (set voltage).
Normal branch/DC/DC operation takes over to supply full power (target voltage).
Thus, Zhang already teaches the sequential behavior Applicant asserts is missing.
2. Applicant’s argument that the DC/DC converter is “always operating” during soft-start does not distinguish the claim.
Applicant asserts that because Zhang’s DC/DC converter outputs energy during soft-start, the reference does not teach a staged process.
However, the claim does not require the DC/DC converter to be inactive during the first stage. It only requires that:
the start unit establishes the bus voltage to a set voltage, and
after that, the DC/DC converter establishes the target voltage.
Zhang teaches exactly this functional sequence:
During soft-start, the second branch (start unit) limits current and controls the rise of the bus voltage.
After the bus voltage reaches the threshold (“close to the voltage at the second end of the DC/DC conversion circuit”), the system switches to the first branch, enabling full DC/DC operation.
The fact that the DC/DC converter is energized does not negate the staged voltage establishment. The functional roles match the claim.
3. Wang further reinforces the obviousness of staged startup control.
Wang teaches the use of impedance and switching elements between the battery cluster and the DC/DC converter to control startup behavior:
“Cin is a filtering capacitance, R1 is a circuit impedance, K1 is a switch between the battery cluster and the DC/DC converter.” Wang ¶[0046]
Wang’s disclosure of controlled startup paths, impedance-based current limiting, and switch-based sequencing would have motivated a POSITA to implement staged voltage establishment exactly the type of behavior Zhang already teaches.
Thus, combining Wang’s startup control with Zhang’s soft-start sequencing would have made the claimed staged voltage establishment obvious.
4. The claimed “start unit” is functionally identical to Zhang’s soft-start circuit.
Applicant argues that Zhang does not disclose a “start unit electrically connected between a battery unit and the DC bus.”
However, Zhang’s FIG. 3 clearly shows:
Battery → DC/DC converter → soft-start circuit → power converter (DC bus)
The soft-start circuit is literally between the battery/DC/DC output and the bus, performing the same function as the claimed start unit.
Zhang ¶[0008] explicitly states that the soft-start circuit is used when the energy storage apparatus is powered on first, which corresponds to Applicant’s “starts through the battery unit.”
Thus, the structural and functional correspondence is direct.
5. The combination of Wang and Zhang still renders the claim obvious.
Even accepting Applicant’s characterization, the differences are at most routine control sequencing. Both references teach:
controlled startup paths
staged voltage establishment
switching between branches based on voltage thresholds
preventing sudden voltage rise
enabling normal DC/DC operation after initial stabilization
A POSITA would have readily combined these teachings to achieve the claimed staged startup.
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 DANIEL KESSIE whose telephone number is (571)272-4449. The examiner can normally be reached Monday-Friday 8am-5pmEst.
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/DANIEL KESSIE/
01/27/2026Primary Examiner, Art Unit 2836
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