Apparatus with active software clamping of supply voltage

A method of regulating a supply voltage of a power tool, the method comprising:

• determining, by a controller, whether the supply voltage of the power tool exceeds a regulating threshold;
• and
• regulating, by a shunt switch and a shunt element, the supply voltage to prevent the supply voltage from exceeding a high voltage threshold;
• wherein regulating the supply voltage includes:
• generating, by the controller, a pulse width modulated control signal;
• controlling a shunt switch according to the pulse width modulated control signal, such that the shunt switch switches between a conducting state and a non-conducting state based on a duty cycle of the pulse width modulated control signal;
• calculating, by the controller, a difference between the supply voltage and the regulating threshold;
• increasing the duty cycle of the pulse width modulated control signal in response to an increase in the difference between the supply voltage and the regulating threshold;
• and
• disconnecting, by the shunt switch, the shunt element thereby preventing the shunt element from conducting current from the supply voltage when the supply voltage does not exceed the regulating threshold.

A power tool comprising:

• a power supply configured to provide power to the power tool;
• a shunt circuit coupled in parallel to the power supply and the, the shunt circuit including a shunt switch and a shunt resistor, the shunt switch including a control terminal and a conducting terminal, and the shunt resistor being connected to the conducting terminal of the shunt switch and configured to conduct current via the conducting terminal;
• a voltage sensor coupled to the power supply and connected in parallel to the shunt circuit;
• a controller coupled to the power supply, the voltage sensor, and to the shunt circuit, the controller configured to
• receive power from the power supply,
• receive a signal from the voltage sensor representative of a supply voltage from the power supply,
• determine if the supply voltage exceeds a regulating threshold, and
• output a control signal to the shunt circuit based on whether the signal representative of the supply voltage exceeds the regulating threshold.