| CPC H02P 21/18 (2016.02) [H02P 23/14 (2013.01)] | 17 Claims |

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1. A power tool, comprising:
an electric motor;
an output shaft connected to the electric motor;
a commutation detection device electrically connected to the electric motor and used for detecting and obtaining commutation information about each commutation of the electric motor; and
a controller electrically connected to at least the electric motor and the commutation detection device and capable of outputting a control signal to control the electric motor to rotate;
wherein the controller is configured to:
receive the commutation information of the electric motor; and
when the commutation information does not match a preset commutation condition, adjust the control signal based on the commutation information such that a rotational speed of the electric motor is maintained to be a target rotational speed,
wherein the controller is configured to:
update a commutation information about the current commutation according to a commutation information about a last commutation when the current commutation of the electric motor is not completed; and
adjust the control signal according to the updated commutation information about the current commutation such that the rotational speed of the electric motor is maintained to be the target rotational speed.
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