Power tool

Patent metadata

Field	Value
Publication number	US-11223315-B2
Application number	US-202016872884-A
Country	US
Kind code	B2
Filing date	May 12, 2020
Priority date	Nov 24, 2017
Publication date	Jan 11, 2022
Grant date	Jan 11, 2022

Abstract

A power tool, includes a power supply module for connecting to AC power; a brushless motor including a rotor and a stator winding; a rectifier module configured to receive the AC power from the power supply module and output a DC bus voltage; a position detection module for detecting a position signal of the brushless motor; a MCU chip configured to receive the position signal of the brushless motor detected by the position detection module and output a driving signal according to the position signal, where the MCU chip includes a controller; and a driving circuit configured to receive the driving signal from the MCU chip to drive the brushless motor, where the driving circuit is connected in series between the MCU chip and the stator winding of the brushless motor.

First claim

What is claimed is:

1. A power tool, comprising:
a power supply module, configured for connecting to AC power;
a brushless motor, comprising a rotor and a stator winding;
a rectifier module, configured to receive the AC power from the power supply module and output a DC bus voltage;
a position detection module, configured for detecting a position signal of the brushless motor;
a MCU chip, configured to receive the position signal of the brushless motor detected by the position detection module and output a driving signal according to the position signal, wherein the MCU chip comprises a controller;
a driving circuit, configured to receive the driving signal from the MCU chip to drive the brushless motor, wherein the driving circuit is connected in series between the MCU chip and the stator winding of the brushless motor; and
a current detection circuit which is configured for detecting a bus current, wherein the controller is configured to, in condition that the bus current detected by the current detection circuit is greater than a preset current value, cut off the driving signal output by the MCU chip, and
wherein the current detection circuit comprises a current detection unit, a comparator, and a diode; the current detection unit is configured for detecting the bus current; the comparator is configured to, in condition that the bus current detected by the current detection unit is greater than the preset current value, output a high level signal to the diode to conduct the diode; and the controller is configured to, in condition that the controller receives a conduction signal of the diode, cut off outputting of the driving signal.

2. The power tool according to claim 1 , further comprising a Hall sensor which is configured for detecting a position of the rotor of the brushless motor, wherein the position detection module is electrically connected to the Hall sensor.

3. The power tool according to claim 1 , wherein the position detection module is a back electromotive force detection module which is configured for detecting a back electromotive force of the brushless motor.

4. A power tool, comprising:
an AC power plug, configured for connecting to an AC power input;
a brushless motor, comprising a rotor and a stator winding;
a rectifier module, wherein the rectifier module is electrically connected to the AC power plug, and is configured to convert the AC power input by the AC power plug into DC power for output;
a back electromotive force detection module, wherein the back electromotive force detection module is electrically connected to the stator winding of the brushless motor, and is configured to detect a back electromotive force of the brushless motor;
a driving circuit, wherein the driving circuit is electrically connected to the stator winding of the brushless motor, and is configured to drive the brushless motor, and the driving circuit has a plurality of driving input terminals;
a MCU chip, wherein the MCU chip is connected between the back electromotive force detection module and the driving circuit, and is configured to output a driving signal to the driving circuit according to the back electromotive force detected by the back electromotive force detection module, and the MCU chip has a plurality of MCU output terminals which are electrically connected to the driving input terminals; and
a current detection circuit, wherein the current detection circuit comprises a current detection unit, a comparator, and a diode, the current detection unit is configured for detecting a bus current, the comparator has a first input terminal, a second input terminal and an output terminal, the first input terminal is electrically connected to the current detection unit to input the bus current, the second input terminal is configured for inputting a preset current value, the output terminal is electrically connected to an anode of the diode, and a cathode of the diode is electrically connected to the MCU chip.

5. The power tool according to claim 4 , further comprising a current detection circuit which is configured for detecting a bus current, wherein the MCU chip is configured to, in condition that the bus current detected by the current detection circuit is greater than a preset current value, cut off the driving signal output from the MCU output terminals.

6. The power tool according to claim 4 , wherein the output terminal of the comparator is configured to, in condition that the bus current is greater than or equal to the preset current value, output a high level signal to conduct the diode; and the MCU chip is configured to, in condition that the MCU chip receives a conduction signal of the diode, cut off the driving signal output from the MCU output terminals.

7. The power tool according to claim 4 , wherein the output terminal of the comparator is configured to, in condition that the bus current is less than the preset current value, output a low level signal to cut off the diode.

Assignees

• Nanjing Chervon Ind Co Ltd

Inventors

• Wang Hongwei
• Chen Weipeng

Classifications

• H02K29/08

  using magnetic effect devices, e.g. Hall-plates, magneto-resistors (H02K29/12 takes precedence) · CPC title

• B24B23/028 Primary

  Angle tools · CPC title

• H02P6/182

  using back-emf in windings · CPC title

• H02H7/08

  for dynamo-electric motors · CPC title

• H02P6/28

  Arrangements for controlling current (H02P6/10 takes precedence) · CPC title