Electric power tool

Patent metadata

Field	Value
Publication number	US-10348227-B2
Application number	US-201615278523-A
Country	US
Kind code	B2
Filing date	Sep 28, 2016
Priority date	Sep 30, 2015
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

One aspect of the present disclosure relates to an electric power tool including a motor, an operation unit, a bridge circuit, and a control unit. The control unit performs a brake control when the motor is braked, and performs a regenerative current inhibition control before stopping the brake control when a drive command is inputted to the operation unit while the brake control is performed.

First claim

What is claimed is:

1. An electric power tool comprising:
a motor;
an operation unit comprising a trigger that initiates a drive command for driving the motor;
a bridge circuit comprising a plurality of switching elements, the bridge circuit being configured to switch current flow paths to the motor by the plurality of switching elements each of the plurality of switching elements including a diode coupled thereto in parallel; and
a control unit configured to control the plurality of switching elements in the bridge circuit according to the drive command inputted to the operation unit, to thereby control driving of the motor, the control unit being further configured to perform a brake control when the motor is braked, and the control unit being further configured to perform, in response to the drive command inputted to the operation unit during the brake control being performed, a regenerative current inhibition control to thereafter stop the brake control, the brake control being set to turn on at least part of the plurality of switching elements in the bridge circuit to generate a braking force on the motor, and the regenerative current inhibition control being set to turn off each of all switching elements that are on, from among the plurality of switching elements in the bridge circuit, at given individual timings to inhibit a regenerative current from flowing in a power source of the motor, each of the given individual timings being a timing that allows a brake current to flow via the diode of each corresponding one of all the switching elements that are on in the bridge circuit.

2. The electric power tool according to claim 1 , wherein the regenerative current inhibition control is set to continue the brake control until a given timing when no further regenerative current flows in the power source of the motor via the bridge circuit.

3. The electric power tool according to claim 1 , wherein the regenerative current inhibition control is set to reduce a brake current flowing in the motor by switching control methods of the brake control.

4. The electric power tool according to claim 1 ,
wherein the motor comprises windings of a plurality of phases,
wherein the brake control is set to control the plurality of switching elements in the bridge circuit to generate the braking force by short-circuiting at least two phases out of the windings of the plurality of phases, and
wherein the regenerative current inhibition control is set to reduce phases short-circuited in the brake control.

5. The electric power tool according to claim 4 ,
wherein the windings of the plurality of phases comprise windings of three phases,
wherein the brake control is set to perform three-phase short-circuit braking that short-circuits the three phases, and
wherein the regenerative current inhibition control is set to perform two-phase short-circuit braking that short-circuits two phases of the three phases.

6. The electric power tool according to claim 5 ,
wherein the brake control is set to perform two-phase short-circuit braking that short-circuits two phases out of the plurality of phases, and
wherein the regenerative current inhibition control is set to perform one-phase short-circuit braking that short-circuits one phase of the two phases.

7. The electric power tool according to claim 5 ,
wherein the brake control is set to perform two-phase short-circuit braking that short-circuits two phases out of the plurality of phases, and
wherein the regenerative current inhibition control is set to perform one-phase short-circuit braking that short-circuits one phase of the two phases.

8. The electric power tool according to claim 1 , wherein the control unit is configured
(i) to perform the brake control at least when the drive command is not inputted thereto from the operation unit,
(ii) to control the plurality of switching elements in the bridge circuit to reduce a brake current flowing in the motor in the regenerative current inhibition control, and
(iii) to start driving the motor without performing the regenerative current inhibition control in response to the drive command inputted to the operation unit under a situation where the control unit is not performing the brake control.

Assignees

• Makita Corp

Inventors

• Ichikawa Yoshitaka

Classifications

• H02P29/0241

  the fault being an overvoltage · CPC title

• H02P23/20

  Controlling the acceleration or deceleration · CPC title

• H02P27/08

  with pulse width modulation · CPC title

• H02K11/215

  Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements · CPC title

• H02P6/24 Primary

  Arrangements for stopping · CPC title