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 .
This action is in response to an application filed on 04/12/2024.
Claims 1-20 are pending for examination.
Claim Objections
Claim 1 is objected to because of the following informalities: the claim recite “BLDC (brushless DC)” in line 1 and it should be re-written as “BLDC (brushless direct current)”. Appropriate correction is required.
Claim 11 is objected to because of the following informalities: the claim recite “BLDC (brushless DC)” in line 1 and it should be re-written as “BLDC (brushless direct current)”. Appropriate correction is required.
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-8 and 11-18 are rejected under 35 U.S.C. 103 as being unpatentable over Nakatsugawa et al. (US 2004/0056632 A1 and Nakatsugawa hereinafter) in view of Brown et al. (US 2014/0265967 A1 and Brown hereinafter).
As to Claims 1 and 11, Nakatsugawa in its teachings as shown in Fig.1-18 disclose a method and a controller (11) for controlling a BLDC motor (4) having a plurality of phases each energized by a different leg (3) of an inverter (see [0038]), the method comprising:
generating (7) a trapezoidal current reference signal for each phase (via inverter 3) of the BLDC motor (4) that has a current ramp-up phase (PA to PD) with a step profile along which the trapezoidal current reference signal has zero slope (PD to PE) for a portion of the current ramp-up phase (PA to PD) and non-zero slope elsewhere (see Fig.4; tru,trv,trw), and a current ramp-down phase (PE to PH) with a step profile along which the trapezoidal current reference signal has zero slope (PH to PI) for a portion of the current ramp-down phase and non-zero slope elsewhere (see [0061] – [0065]),
Although a method and a controller for generating a trapezoidal current reference signal for each phase of the BLDC motor is thought as shown above (see also [0097]), it doesn’t explicitly disclose:
adjusting a duty cycle of a switching control signal for each leg of the inverter, such that a current through each inverter leg is forced to follow the trapezoidal current reference signal for the corresponding phase
Nonethless, Brown in its teachings as shown in Fig.1-7 disclose a pulse width modulated (PWM) trapezoidal commutation drive to a brushless direct current (BLDC) motor is sine modified so that the applied drive voltage substantially matches the induced voltage generated in the BLDC motor and the values of the cosine of the angles between -30 degrees and +30 degrees are used to modify the duty cycle of the PWM drive signal dependent upon the rotor angular positions determined from the times between the zero crossing BEMF voltages measured at the unconnected motor terminals (see [Abstract])
Therefore, it would have been an obvious modification before the effective filing date of the instant application to adjust/modify the duty cycle of the trapezoidal current as thought by Brown within the teachings of Nakatsugawa in order to generate modified trapezoidal drive to BLDC motors.
As to Claims 2 and 12, Nakatsugawa in view of Brown disclose the method of claim 1 and the controller of claim 11, wherein for each electrical cycle of each trapezoidal current reference signal, the trapezoidal current reference signal is generated to indicate that a high-side switch device and a low-side switch device of the corresponding inverter leg perform active switching during the current ramp-up phase and the current ramp-down phase and are off together for the portion of the current ramp-up phase and the portion of the current ramp-down phase when the trapezoidal current reference signal has zero slope (see (tru,trv,trw) and also [0038]-[0044], [0056] – [0066] and [0097]).
As to Claims 3 and 13, Nakatsugawa in view of Brown disclose the method of claim 2 and the controller of claim 12, wherein the trapezoidal current reference signal for each phase of the BLDC motor has a high-side on phase that follows the current ramp-up phase and a low-side on phase that follows the current ramp-down phase (see (tru,trv,trw) and also [0038]-[0044], [0056] – [0066] and [0097]).
As to Claims 4 and 14, Nakatsugawa in view of Brown disclose the method of claim 3 and the controller of claim 13, wherein for each electrical cycle of each trapezoidal current reference signal, the trapezoidal current reference signal is generated to indicate the following for the corresponding inverter leg: that the high-side switch device should be on and the low-side switch device off during at least part of the high-side on phase; and that the low-side switch device should be on and the high-side switch device off during at least part of the low-side on phase (see (tru,trv,trw) and also [0038]-[0044], [0056] – [0066] and [0097]).
As to Claims 5 and 15, Nakatsugawa in view of Brown disclose the method of claim 3 and the controller of claim 13, wherein for each electrical cycle of each trapezoidal current reference signal, the trapezoidal current reference signal is generated to indicate the following for the corresponding inverter leg: that the high-side switch device and the low-side switch device should be off at the same time for 60 electrical degrees subtracting both the current ramp-up phase and the current ramp-down phase (see (tru,trv,trw) and also [0038]-[0044], [0056] – [0066] and [0097]).
As to Claims 6 and 16, Nakatsugawa in view of Brown disclose the method of claim 1 and the controller of claim 11, wherein the trapezoidal current reference signal for each phase of the BLDC motor is generated based on a maximum current level for the BLDC, a ramp signal for the phase, and a rotor position estimate for the phase (see trumax and also [0038]- [0044], [0056] – [0066] and [0097]).
As to Claims 7 and 17, Nakatsugawa in view of Brown disclose the method of claim 6 and the controller of claim 16, wherein the ramp signal has an adjustable ramp rate (Brown: see [0011] and [0034]- [0036]).
As to Claims 8 and 18, Nakatsugawa in view of Brown disclose the method of claim 1 and the controller of claim 11, wherein adjusting the duty cycle of the switching control signal for each leg of the inverter comprises: tracking a difference between the trapezoidal current reference signal for the corresponding phase and a measure or estimate of the phase current; and adjusting the duty cycle so as to reduce the difference (Brown: see [0011] and [0034] - [0036]).
Allowable Subject Matter
Claims 9, 10, 19 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 and any intervening claims.
As to Claim 9, 10, 19 and 20: In view of the limitations the closest prior art including the prior works of the assignee/inventor does not explicitly describe or reasonably suggest or render obvious in combination with all the given limitations wherein adjusting the duty cycle of the switching control signal for each leg of the inverter further comprises: inputting the trapezoidal current reference signal for the corresponding phase into a feedforward control loop; and adjusting the duty cycle based on the difference between the trapezoidal current reference signal for the corresponding phase and the measure or estimate of the phase current, and based on an output of the feedforward control loop; nor adjusting the duty cycle based on an output of the feedforward control loop, without any phase current feedback.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure (US 2005/0201129 A1: A control apparatus and a semiconductor apparatus of AC motors capable of reducing torque ripple with a comparatively simple circuit corresponding to a high withstand voltage and capable of driving a motor at high efficiency even when the rotational speed or load has changed. The control apparatus detects first phase signals fixed in relative phase to induced voltages of the motor and current polarity signals, recognizes phase differences between them, generates second phase signals so as to make the phase differences approach zero to drive the motor at high efficiency, generates modulation wave signals having quasi-sinusoidal waveforms or trapezoidal waveforms on the basis of the second phase signals, compares the modulation wave signals with a carrier wave signal, and conducts PWM control on an inverter -see [Abstract]).
Any inquiry concerning this communication or earlier communications from the examiner should be directed to GABRIEL T AGARED whose telephone number is (571)270-1981. The examiner can normally be reached 8-5 (Mon- Thur).
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/GABRIEL AGARED/Primary Examiner, Art Unit 2846
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