Motor braking using selectively connectable resistance

A method for braking a motor of a power tool comprising:

• controlling, using a motor controller of the power tool, a power switching network to drive the motor of the power tool in response to actuation of a user input;
• determining, using the motor controller, a variable tool characteristic;
• determining, using the motor controller, that the user input is de-actuated;
• determining, using the motor controller, whether the variable tool characteristic satisfies a tool characteristic threshold in response to the user input being de-actuated;
• controlling, using the motor controller, the power switching network to brake the motor when the variable tool characteristic satisfies the tool characteristic threshold;
• and
• controlling, using the motor controller, a braking circuit to brake the motor when the variable tool characteristic does not satisfy the tool characteristic threshold, wherein the braking circuit having one or more resistive loads is selectively coupled to motor terminals of the motor,
• wherein the variable tool characteristic is a motor current and wherein the variable tool characteristic satisfies the tool characteristic threshold when the motor current is below a regenerative braking threshold.

A power tool comprising:

• a motor;
• a power switching network coupled between a power source and the motor;
• a braking circuit including one or more resistive loads and configured to be selectively coupled to motor terminals of the motor, wherein the braking circuit is configured to selectively couple the motor terminals to one selected from the group consisting of ground and a terminal of the power source;
• and
• a controller connected to the power switching network and the braking circuit, the controller configured to:
• determine a motor current of the motor,
• determine whether the motor current is below a regenerative braking threshold,
• control the power switching network to brake the motor when the motor current is below the regenerative braking threshold, and
• control the braking circuit to brake the motor when the motor current is greater than or equal to the regenerative braking threshold,
• wherein the regenerative braking threshold is a current value of the motor current that safely charges the power source during braking of the motor.