DETAILED ACTION
1. The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
2. The specification, the abstract and the drawings are all acceptable.
Claim Rejections - 35 USC § 103
3. 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 of this title, 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.
4. Claims 1-2, 6-9, 13-15 are rejected under 35 U.S.C. 103 as being unpatentable over USPN 9,143,066 to Yang in view of USPN 10,084,399 to Campbell, and further in view of USPN 11,791,750 to Xu.
As to claim 1, Yang teaches the controller (fig. 1: “108”) is configured to: operate a sliding-mode observer SMO process to estimate a back electromotive force back-EMF voltage of the motor based on a phase current of the motor(col. 1: lines 58-64) and detect an angular position of the rotor based on the estimated back-EMF voltage(col. 5: lines 58-64).
Yang does not an apparatus to predict an occurrence of a stall condition based on at least one of a rotational speed of the rotor or the phase current of the motor and operate a high-frequency injection HFI process in response to predicting the occurrence of the stall condition, wherein the HFI process includes injecting a plurality of voltage pulses to the motor and detecting corresponding high-frequency current components to determine the angular position of the rotor; determine whether the stall condition has occurred; and transition from the SMO process to the HFI process in response to the determination of the stall condition has occurred and a power tool comprising: a housing; a brushless motor disposed within the housing, the motor comprising a stator having a plurality of windings and a rotor; a power switch circuit that supplies power from a power source to the brushless motor; and a controller configured to apply a drive signal to the power switch circuit to control the supply of power to the brushless motor.
Campbell teaches an apparatus to predict an occurrence of a stall condition based on at least one of a rotational speed of the rotor(col. 9: lines 58-61) or the phase current of the motor and operate a high-frequency injection HFI process in response to predicting the occurrence of the stall condition, wherein the HFI process includes injecting a plurality of voltage pulses to the motor and detecting corresponding high-frequency current components to determine the angular position of the rotor; determine whether the stall condition has occurred(col. 4: lines 6-25 & col. 9: lines 58-61) and transition from the SMO process to the HFI process (fig. 8: “840”) in response to the determination of the stall condition has occurred determine whether the stall condition has occurred(fig. 8: “820”).
Xu teaches a power tool comprising: a housing; a brushless motor disposed within the housing, the motor comprising a stator having a plurality of windings and a rotor; a power switch circuit that supplies power from a power source to the brushless motor; and a controller configured to apply a drive signal to the power switch circuit to control the supply of power to the brushless motor(col. 1: lines 49-61).
Thus, it would have been obvious to one of ordinary skill in the art before the
effective filing date of the claimed invention to implement the teachings of Campbell and Xu into Yang since Yang suggests a motor control system and Campbell and Xu suggests the beneficial use of HFI process for motor speed determination/motor stall detection and use a brushless motor for a power tool in the analogous art of motor control technology.
The motivation for this comes from the fact that Yang and Campbell teaches the SMO and HFI techniques for motor speed and motor stall detection which can be used to improve the power tool motor control system disclosed by Xu.
As to claim 2, Yang in view of Campbell and Xu teaches the power tool of claim 1, wherein the controller is configured to determine that the stall condition has occurred by comparing a present angular position of the rotor to a previous angular position of the rotor and determining whether a difference between the present angular position of the rotor and the previous angular position of the rotor exceeds a stall angle threshold(Campbell col. 9: lines 58 – col. 10: lines 3).
As to claim 6, Yang in view of Campbell and Xu teaches the power tool of claim 1, wherein the controller is configured to predict the occurrence of the stall condition if the rotational speed of the rotor falls below a speed threshold (Campbell col. 9: lines 58-61) and the phase current of the motor exceeds a current threshold(Campbell col. 9: lines 35-48).
As to claim 7, Yang in view of Campbell and Xu teaches the power tool of claim 1, wherein the controller is configured to terminate the HFI process if the stall condition does not occur within a predetermined amount of time(Campbell fig. 8: “830” wherein the stall condition does not occur so that the HFI process terminates).
As to claim 8, it is rejected as the same reason as claim 1.
As to claim 9, Yang in view of Campbell and Xu teaches the method of claim 8, where the step of determining whether the stall condition has occurred comprises: comparing a present angular position of the rotor to a previous angular position of the rotor, and determining whether a difference between the present angular position of the rotor and the previous angular position of the rotor exceeds a stall angle threshold.
As to claim 13, Yang in view of Campbell and Xu teaches the method of claim 8, wherein the predicting step comprises predicting the occurrence of the stall condition if the rotational speed of the rotor falls below a speed threshold and the phase current of the motor exceeds a current threshold (Campbell col. 9: lines 58 – col. 10: lines 3).
As to claim 14, Yang in view of Campbell and Xu teaches the method of claim 8, further comprising terminating the HFI process if the stall condition does not occur within a predetermined amount of time (Campbell fig. 8: “830” wherein the stall condition does not occur so that the HFI process terminates).
As to claim 15, it is rejected as the same reason as claim 1.
Allowable Subject Matter
5. Claims 3-5,10-12 are objected to as being dependent upon the rejected base claims 1, 8, but could be allowable if rewritten in independent form including all of the limitations of the base claims and any intervening claims for the following reasons: No prior art of record discloses the features as claimed in the noted claims.
6. The following is a statement of reasons for the indication of allowable subject matter. The non-obvious features are:
In comparison with the closest prior art as cited in this Office action and any previous Office actions, no prior art of record discloses the following features as claimed in the following claim limitations:
As per claim 3: The controller is configured to set the stall angle threshold as a function of the present angular position of the rotor as determined by the SMO process.
As per claim 4: The controller is configured to set the angular position of the rotor to an output of the SMO process while the SMO process and the HFI process are operated simultaneously after the stall condition is predicted but before the stall condition has occurred.
As per claim 5: The controller is configured to converge the angular position of the rotor obtained from the SMO process and the angular position of the rotor obtained from the HFI process prior to the transition from the SMO process to the HFI process.
As per claim 10: Setting the stall angle threshold as a function of the present angular position of the rotor as determined by the SMO process.
As per claim 11: Setting the angular position of the rotor to an output of the SMO process while the SMO process and the HFI process are operated simultaneously after the stall condition is predicted but before the stall condition has occurred.
As per claim 12: Converging the angular position of the rotor obtained from the SMO process and the angular position of the rotor obtained from the HFI process prior to the transition from the SMO process to the HFI process.
Conclusion
7. The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
USPN 10,958,201 to Lan discloses a brushless motor control system having the motor stall detection technique.
8. Any inquiry concerning this communication or earlier communications from the examiner should be directed to DAVID S LUO whose telephone number is (571)270-5251. The examiner can normally be reached 8AM-5PM.
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/DAVID LUO/Primary Examiner, Art Unit 2846