Control scheme to increase power output of a power tool using conduction band and advance angle
First Claim
1. A power tool, comprising:
- a brushless direct current (BLDC) motor having a stator defining a plurality of phases;
a switching arrangement having a plurality of motor switches connected electrically between a power source and the BLDC motor and operates to deliver power to the BLDC motor;
an input unit operates between an initial position and an end position and outputs a signal indicative of target power delivered to the BLDC motor in accordance with position of the input unit; and
a controller interfaced with the input unit and the plurality of motor switches and operates to, for each phase;
output a pulse-width modulated (PWM) signal having a duty cycle to one or more of the plurality of motor switches to control supply of power to the BLDC motor;
control a conduction band of the one or more of the plurality of motor switches corresponding to the phase of the BLDC motor;
within a first positional range of the input unit between the initial position and a predetermined position, increase the supply of power to the BLDC motor by increasing the duty cycle of the PWM signal from a minimum duty cycle to a maximum duty cycle as a function of the position of the input unit while keeping the conduction band constant at a minimum conduction band; and
within a second positional range of the input unit between the predetermined position and an end position, increase the supply of power to the BLDC motor by increasing the conduction band from the minimum conduction band to a maximum conduction band as a function of the position of the input unit while keeping the duty cycle constant at the maximum duty cycle.
1 Assignment
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Accused Products
Abstract
A power tool includes a multi-phase BLDC motor, a plurality of switches, an input unit, and a controller. For each phase, the controller operates to vary power output to the motor between a first power and a second power by varying a duty cycle of a PWM signal from 0% to 100% while keeping a conduction band (CB) of corresponding motor switches and/or an advance angle (AA) at a predetermined value when the input unit moves between a first position and a predetermined position between the first and a second position. For each phase, the controller operates to increase the power output by the motor to greater than the second power by increasing the CB/AA to greater than the predetermined value while keeping the duty cycle of the PWM signal at 100% when the input unit moves between the predetermined position and the second position.
160 Citations
20 Claims
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1. A power tool, comprising:
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a brushless direct current (BLDC) motor having a stator defining a plurality of phases; a switching arrangement having a plurality of motor switches connected electrically between a power source and the BLDC motor and operates to deliver power to the BLDC motor; an input unit operates between an initial position and an end position and outputs a signal indicative of target power delivered to the BLDC motor in accordance with position of the input unit; and a controller interfaced with the input unit and the plurality of motor switches and operates to, for each phase; output a pulse-width modulated (PWM) signal having a duty cycle to one or more of the plurality of motor switches to control supply of power to the BLDC motor; control a conduction band of the one or more of the plurality of motor switches corresponding to the phase of the BLDC motor; within a first positional range of the input unit between the initial position and a predetermined position, increase the supply of power to the BLDC motor by increasing the duty cycle of the PWM signal from a minimum duty cycle to a maximum duty cycle as a function of the position of the input unit while keeping the conduction band constant at a minimum conduction band; and within a second positional range of the input unit between the predetermined position and an end position, increase the supply of power to the BLDC motor by increasing the conduction band from the minimum conduction band to a maximum conduction band as a function of the position of the input unit while keeping the duty cycle constant at the maximum duty cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A power tool, comprising:
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a brushless direct current (BLDC) motor having a stator defining a plurality of phases; a switching arrangement having a plurality of motor switches connected electrically between a power source and the BLDC motor and operates to deliver power to the BLDC motor; an input unit operates between an initial position and an end position and outputs a signal indicative of target power delivered to the BLDC motor in accordance with position of the input unit; and a controller interfaced with the input unit and the plurality of motor switches and operates to, for each phase; output a pulse-width modulated (PWM) signal having a duty cycle to one or more of the plurality of motor switches to control supply of power to the BLDC motor; control an advance angle of the one or more of the plurality of motor switches corresponding to the phase of the BLDC; within a first positional range of the input unit between the initial position and a predetermined position, increase the supply of power to the BLDC motor by increasing the duty cycle of the PWM signal from a minimum duty cycle to a maximum duty cycle as a function of the position of the input unit while keeping the advance angle constant at a minimum advance angle; and within a second positional range of the input unit between the predetermined position and an end position, increase the supply of power to the BLDC motor by increasing the advance angle from the minimum advance angle to a maximum advance angle as a function of the position of the input unit while keeping the duty cycle constant at the maximum duty cycle. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification