Dual-inverter for a brushless motor

Patent metadata

Field	Value
Publication number	US-10833611-B2
Application number	US-201715699040-A
Country	US
Kind code	B2
Filing date	Sep 8, 2017
Priority date	Sep 9, 2016
Publication date	Nov 10, 2020
Grant date	Nov 10, 2020

Abstract

A power tool is provided including: an electric brushless direct current (BLDC) motor having rotor and a stator defining phases; a power unit including a first switch circuit connected electrically between a first power supply and the motor, and a second switch circuit connected electrically between a second power supply and the motor; and a controller configured to control a switching operation of the first switch circuit and the second switch circuit to regulate a supply of power from at least one of the first power supply and/or the second power supply to the motor.

First claim

The invention claimed is:

1. A power tool comprising:
an electric brushless direct current (BLDC) motor having a rotor and a stator defining a plurality of phases, the stator including a first set of stator windings and a second set of stator windings;
a first set of battery terminals that couples to a first battery pack to receive direct current (DC) power from the first battery pack;
a second set of battery terminals that couples to a second battery pack to receive direct current (DC) power from the second battery pack;
a power unit including: a first switch circuit having output nodes connected electrically to the first set of stator windings, and a second switch circuit having output nodes connected electrically to the second set of stator windings;
a selector switch configured to selectively couple the first set of battery terminals to input nodes of the second switch circuit in a single-battery pack mode of operation where the only first battery pack is provided so both the first set of stator windings and the second set of stator windings are powered from the first battery pack, and to selectively couple the second set of battery terminals to the input nodes of the second switch circuit in a dual-battery pack mode of operation where both the first battery pack and the second battery pack are provided so that the first set of stator windings is powered from the first battery pack and the second set of stator windings is powered from the second battery pack in parallel; and
a controller configured to control switching operations of the first switch circuit and the second switch circuit to regulate a supply of power to the motor.

2. The power tool of claim 1 , wherein the first and second battery packs both comprises removeable 20V max power tool battery packs.

3. The power tool of claim 1 , wherein the first switch circuit and the second switch circuit both comprise a plurality of insulated-gate bipolar transistors (IGBTs) or a plurality of field-effect transistors (FETs).

4. The power tool of claim 1 , wherein the first and second battery packs have the same maximum voltage and, when the first and second battery packs are both coupled to the first and second sets of battery terminals respectively, the controller controls the switching operations of the first switch circuit and the second switch circuit so as to approximately double the runtime of the first and second battery packs, and operate the motor at a voltage corresponding to the voltage of the first and second battery packs.

5. The power tool of claim 1 , wherein the controller is configured to control motor commutation by concurrently driving the first switch circuit and the second switch circuit using one set of drive signals.

6. The power tool of claim 1 , wherein the first set of windings and the second set of windings are alternatingly disposed around the stator.

7. The power tool of claim 1 , wherein the selector switch includes no output nodes coupled to the first switch circuit.

8. The power tool of claim 1 , wherein the first switch circuit is electrically isolated from the second switch circuit.

9. A power tool comprising:
an electric brushless direct current (BLDC) motor having a rotor and a stator defining a plurality of phases associated with a plurality of windings;
a power unit including a first switch circuit connected electrically between a first set of battery terminals and a first set of stator windings of the plurality of windings and a second switch circuit connected electrically between a second set of battery terminals and a second set of windings of the plurality of windings, wherein the first set of battery terminals receives direct current (DC) power from a first battery pack when coupled to the first battery pack, and the second set of battery terminals receives DC power from a second battery pack when coupled to the second battery pack;
a selector switch that couples the first set of battery terminals to the second switch circuit in a first mode of operation where the first battery pack is coupled to the first set of battery terminals but the second battery pack is not coupled to the second set of battery terminals, but couples the second set of battery terminals to the second switch circuit in a second mode of operation where both the first battery pack and the second battery pack are respectively coupled to the first set of battery terminals and the second set of battery terminals; and
a controller configured to control switching operations of the first switch circuit and the second switch circuit to regulate a supply of power to the motor such that, in the first mode of operation, the first switch circuit energizes the first set of stator windings from the first battery pack and the second switch circuit energizes the second set of stator windings from the second battery pack, the first and second switch circuits being electrically isolated so as to draw current in a parallel configuration from the first and second battery packs while electrically isolating the first and second battery packs to prevent flow of current between the first and second battery packs, and in the second mode of operation, both the first switch circuit and the second switch circuit respectively energize the first set of stator windings and the second set of stator windings from the first battery pack.

10. The power tool of claim 9 , wherein first and second battery packs have the same maximum voltage and, when the first and second battery packs are both coupled to the first and second sets of battery terminals respectively, the controller controls the switching operations of the first switch circuit and the second switch circuit so as to approximately double the runtime of the first and second battery packs, and operate the motor at a voltage corresponding to the voltage of the first and second battery packs.

11. The power tool of claim 9 , wherein the first and second battery packs both comprise removeable 20V max power tool battery packs.

12. The power tool of claim 9 , wherein the first switch circuit and the second switch circuit both comprise a plurality of insulated-gate bipolar transistors (IGBTs).

13. The power tool of claim 9 , wherein the first switch circuit and the second switch circuit both comprise a plurality of field-effect transistors (FETs).

14. The power tool of claim 9 , wherein the controller is configured to control motor commutation by concurrently driving the first switch circuit and the second switch circuit using one set of drive signals.

15. The power tool of claim 9 , wherein the selector switch includes no output nodes coupled to the first switch circuit.

16. A power tool comprising:
an electric brushless direct current (BLDC) motor having a rotor and a stator defining a plurality of phases, the stator including a first set of stator windings and a second set of stator windings;
a first power supply interface that receives direct current (DC) power from a first battery pack;
a second power supply interface that receives direct current (DC) power from a second battery pack;
a power unit including a first switch circuit and a second switch circuit arranged to respectively switchably energize the first set of stator windings and the second set of stator windings from one or both of the first battery pack and the second battery pack;
a selector switch that couples the first battery pack to both the first switch circuit and the second switch circuit in a first switch position wherein only the first battery pack is coupled to the power tool, and couples the first battery pack to the first switch circuit an

Assignees

• Black & Decker Inc

Inventors

• Cox John D

Classifications

• H02P25/184 Primary

  wherein the motor speed is changed by switching from a delta to a star, e.g. wye, connection of its windings, or vice versa · CPC title

• H02J9/061

  for DC powered loads · CPC title

• H02P6/085

  in a bridge configuration · CPC title

• H02P6/12 Primary

  Monitoring commutation; Providing indication of commutation failure · CPC title

• H02P25/22

  Multiple windings; Windings for more than three phases · CPC title