Snap-on Inc.

Daniel Nitzsche

Jason Genz

Michael T Rajzer

Christoffer S Fox

The present invention relates to a method of commutation control of a brushless DC (BLDC) motor. The method uses a controller to control the BLDC motor using a modified six-step commutation. The method adds six intermediate steps that overlap the six-step commutation. Each of the six steps overlap with preceding and following steps, resulting in six additional intermediate steps in which all three phases are active. By doubling the number of steps, current and torque will vary less over time compared with current solutions without increasing the size or changing the design of the motor.

Controlling brushless motor commutation

The present invention relates broadly to commutation control of a BLDC motor for use with, for example, a power tool. The method uses a controller to control a BLDC motor in the event of a position sensor failure. Rather than ceasing operation of the motor and indicating a fault or error message to the user, the present invention determines when the next transition should occur based on the time between past hall transitions using a timer. Thus, if one or two position sensors are no longer providing position information to the controller, the controller can determine when the transitions would be changing based on past transitions to continue controlling the motor and prevents the motor from ceasing operation.

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Kenosha, WI, United States of America

Daniel Nitzsche