Power tool
AssigneeNanjing Chervon Industry Co., Ltd.
InventorZhen Xu
Life of this patent
Estimating the term…
Abstract
A power tool includes an electric motor including multi-phase windings; and a control circuit for controlling the electric motor to rotate. The control circuit includes a driver circuit including multiple switching elements having multiple driving states to drive the electric motor to rotate; a parameter detection module for detecting an electrical parameter of the control circuit; and a controller for outputting a pulse-width modulation (PWM) control signal to control the driver circuit to change the multiple driving states. The controller is configured to change the absolute value of the variation of a duty cycle of the PWM control signal according to the electrical parameter to control a steady-state error of the electric motor running in a constant speed to be within a preset range.
Claims18
A power tool, comprising:
- an electric motor comprising multi-phase windings;
- and
- a control circuit for controlling the electric motor to rotate;
- wherein the control circuit comprises:
- a driver circuit comprising a plurality of switching elements having a plurality of driving states to drive the electric motor to rotate;
- a parameter detection module for detecting an electrical parameter of the control circuit;
- and
- a controller for outputting a pulse-width modulation (PWM) control signal to control the driver circuit to change the plurality of driving states;
- wherein the controller is configured to change an absolute value of a variation of a duty cycle of the PWM control signal according to the electrical parameter to control a steady-state error of the electric motor running in a constant speed to be within a preset range;
- and
- wherein an average inductance of each phase winding is greater than or equal to 0.9 mH.
A power tool, comprising:
- an electric motor comprising multi-phase windings;
- and
- a control circuit for controlling the electric motor to rotate,
- wherein the control circuit comprises:
- a driver circuit comprising a plurality of switching elements having a plurality of driving states to drive the electric motor to rotate;
- a parameter detection module for detecting an electrical parameter of the control circuit;
- and
- a controller for outputting a pulse-width modulation (PWM) control signal to control the driver circuit to change the plurality of driving states;
- wherein the controller is configured to change a magnitude of a variation of a duty cycle of the PWM control signal according to the electrical parameter to control a phase current magnitude when the electric motor commutates to be less than 70 A;
- and
- wherein an average inductance of each phase winding is greater than or equal to 0.9 mH.
A power tool, comprising:
- an electric motor comprising multi-phase windings;
- and
- a control circuit for controlling the electric motor to rotate;
- wherein the control circuit comprises:
- a driver circuit comprising a plurality of switching elements having a plurality of driving states to drive the electric motor to rotate;
- a parameter detection module for detecting an electrical parameter of the control circuit;
- and
- a controller for outputting a pulse-width modulation (PWM) control signal to control the driver circuit to change the plurality of driving states;
- wherein the controller is configured to change an absolute value of a variation of a duty cycle of the PWM control signal according to the electrical parameter to control a steady-state error of the electric motor running in a constant speed to be within a preset range;
- and
- wherein the control circuit further comprises a filter capacitor and a capacitance of the filter capacitor is less than or equal to 20 μF.
Dependencies are inferred from the claim text.