Selectable current limiting for power tool
AssigneeMilwaukee Electric Tool Corporation
InventorBenjamin F. Shaske
Life of this patent
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Abstract
Selectable current limiting for a power tool. One embodiment provides a method for selectable current limiting for a power tool including determining, using a current sensor, an average current and determining whether the average current exceeds a predetermined current threshold. The method also includes determining a deviation of the average current from the predetermined current threshold and reducing a PWM duty ratio proportional to the deviation of the average current from the predetermined current threshold. The PWM duty ratio corresponds to a PWM signal provided to an inverter bridge.
Claims20
A power tool comprising:
- a housing;
- a motor within the housing;
- a current sensor configured to measure a current flow to the motor;
- an inverter bridge selectively providing power from a power source to the motor;
- and
- an electronic processor connected to the current sensor and the inverter bridge, the electronic processor is configured to:
- determine, using the current sensor, an average current,
- determine whether the average current exceeds a predetermined current threshold,
- determine a deviation of the average current from the predetermined current threshold, and
- reduce a pulse-width-modulated (“PWM”) duty ratio proportionally to the deviation of the average current from the predetermined current threshold,
- wherein the PWM duty ratio corresponds to a PWM signal provided to the inverter bridge.
A method for selectable current limiting for a power tool, the method comprising:
- driving, using an inverter bridge of the power tool, a motor of the power tool;
- determining, using a current sensor of the power tool, an average current flowing to the motor;
- determining, using an electronic processor of the power tool, whether the average current exceeds a predetermined current threshold;
- determining, using the electronic processor, a deviation of the average current from the predetermined current threshold;
- and
- reducing, using the electronic processor, a PWM duty ratio proportionally to the deviation of the average current from the predetermined current threshold,
- wherein the PWM duty ratio corresponds to a PWM signal provided to the inverter bridge.
A power tool comprising:
- a housing;
- a motor within the housing;
- a current sensor configured to measure a current flow to the motor;
- an inverter bridge selectively providing power from a power source to the motor;
- and
- an electronic processor connected to the current sensor and the inverter bridge, the electronic processor is configured to:
- determine, using the current sensor, an average current,
- determine whether the average current exceeds a predetermined current threshold,
- determine a deviation of the average current from the predetermined current threshold, and
- reduce a pulse-width-modulated (“PWM”) duty ratio based on the deviation of the average current from the predetermined current threshold,
- wherein the PWM duty ratio corresponds to a PWM signal provided to the inverter bridge.
Dependencies are inferred from the claim text.