Abstract: Power tools that include a housing, a motor supported by the housing, an inverter positioned between and electrically connected to a battery pack interface and the motor, a gate driver connected to the inverter, a rotational position detector configured to detect a position of the motor, a controller configured to control the gate driver, and a short circuit detection circuit. The short circuit detection circuit is configured to monitor the current in the inverter, compare the current in the inverter to a first current threshold, determine, in response to the current in the inverter being greater than or equal to the first current threshold, whether the position of the motor is changing based on a signal from the rotational position detector, and control, in response to the position of the motor not changing, a switch of the short circuit detection circuit to disable the gate driver.

Abstract: Power tools that include a housing, a motor supported by the housing, a battery pack interface configured to receive a battery pack that includes a plurality of battery cells, an inverter positioned between and electrically connected to the battery pack interface and the motor, a gate driver connected to the inverter and configured to control a current in the inverter, a controller configured to control the gate driver, and a short circuit detection circuit. The short circuit detection circuit is configured to monitor the current in the inverter, compare the current in the inverter to a short circuit threshold, and control a switch of the short circuit detection circuit to disable the gate driver when the current in the inverter is greater than or equal to the short circuit threshold.

Abstract: A power tool device that includes a housing, a battery pack interface configured to receive at least one battery pack, a first battery pack terminal and a second battery pack terminal, a low quiescent current direct current (“DC”) link bus discharge circuit including a DC link bus capacitance, a first DC link bus switch, and a second DC link bus switch, and a controller. The controller is configured to monitor a voltage of the first battery pack terminal, monitor a voltage of the second battery pack terminal, turn ON the first DC link bus switch and the second DC link bus switch when the voltage of the first battery pack terminal is greater than a first threshold value and the voltage of the second battery pack terminal is zero volts.