Controlled power fade for battery power devices
First Claim
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1. A method for operating a power tool having a motor powered by a battery pack, the method being executed via a controller residing in the power tool, the method comprising:
- setting the duty cycle of a pulse width modulated (PWM) control signal for driving the motor to a first PWM value in accordance with a desired rotational speed of the motor;
delivering power from the battery pack to the motor in accordance with the control signal;
monitoring a parameter associated with at least one of battery operation or tool operation while power is delivered from the battery pack to the motor;
detecting a condition of the parameter indicative of a shutdown condition; and
fading the power delivered from the battery to the motor, in response to the detected condition, wherein the fading step comprises;
computing a second PWM value based on a value of the parameter, andsetting the duty cycle of the control signal to the second PWM value when the second PWM value is less than the first PWM value, and retaining the duty cycle at the first PWM value set in accordance with the desired rotational speed of the motor when the second PWM value is more than the first PWM value.
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Abstract
A method is provided for operating a power tool having a motor powered by a battery. The method includes: delivering power from the battery to the motor in accordance with an operator input; detecting a condition of the power tool indicating a shutdown of the power is imminent; and fading the power delivered from the battery to the motor, in response to the detected condition, through the use of a controller residing in the power tool.
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Citations
16 Claims
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1. A method for operating a power tool having a motor powered by a battery pack, the method being executed via a controller residing in the power tool, the method comprising:
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setting the duty cycle of a pulse width modulated (PWM) control signal for driving the motor to a first PWM value in accordance with a desired rotational speed of the motor; delivering power from the battery pack to the motor in accordance with the control signal; monitoring a parameter associated with at least one of battery operation or tool operation while power is delivered from the battery pack to the motor; detecting a condition of the parameter indicative of a shutdown condition; and fading the power delivered from the battery to the motor, in response to the detected condition, wherein the fading step comprises; computing a second PWM value based on a value of the parameter, and setting the duty cycle of the control signal to the second PWM value when the second PWM value is less than the first PWM value, and retaining the duty cycle at the first PWM value set in accordance with the desired rotational speed of the motor when the second PWM value is more than the first PWM value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A power tool system comprising:
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a tool assembly having a motor; a battery pack that selectively couples to the tool assembly and operates to provide power to the motor; a discharge control module that regulates power provided to the motor by setting a duty cycle of pulse width modulated (PWM) control signal of a switch disposed in series with the motor to a first PWM value in accordance with a desired rotational speed of the motor, wherein the discharge control module is configured to monitor a parameter associated with at least one of battery operation or tool operation while power is delivered from the battery pack to the motor, detect a condition of the parameter indicative of a shutdown condition, and fade the power delivered from the battery to the motor by adjusting the duty cycle of the control signal by an amount based on a value of the parameter, wherein the discharge control module computes a second PWM value based on the value of the parameter, sets the duty cycle of the control signal to the second PWM value when the second PWM value is less than the first PWM value, and retains the duty cycle at the first PWM value set in accordance with the desired rotational speed of the motor when the second PWM value is more than the first PWM value. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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Specification