Permanent magnet electric machine

• US 10,184,442 B2
• Filed: 05/19/2016
• Issued: 01/22/2019
• Est. Priority Date: 05/19/2016
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Hao, Lei, Namuduri, Chandra S., Pandi, Murali, Nehl, Thomas W.
• Primary Examiner(s): Kim, John K
• Application Number:
  US15/158,887
• Publication Number:
  US 20170334297A1
• Time in Patent Office: 978 Days
• Field of Search: 310 58, 31015601, 31015653, 31015656
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 6/20 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
• CPC Class Codes: B60L 2220/50 Structural details of electrical machines
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: F02N 11/006 using a plurality of electric motors
• CPC Class Codes: F02N 11/0851 characterised by means for controlling the engagement or disengagement between engine and starter, e.g. meshing of pinion and engine gear
• CPC Class Codes: F02N 11/0862 characterised by the electrical power supply means, e.g. battery
• CPC Class Codes: F02N 2200/022 Engine speed
• CPC Class Codes: F02N 2300/102 Control of the starter motor speed; Control of the engine speed during cranking
• CPC Class Codes: H02K 1/276 Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
• CPC Class Codes: H02K 21/16 having annular armature cores with salient poles with homopolar co-operation H02K21/20
• CPC Class Codes: H02K 7/006 Structural association of a motor or generator with the drive train of a motor vehicle

Abstract

An interior permanent magnet electric machine includes a stator having a plurality of teeth disposed around a circumference oriented radially towards a center defining slots interposed between each of the teeth, and a conductive winding wrapped around each of the teeth of the stator to receive an electrical current. The electric machine also includes a rotor which is rotatable relative to the stator. The rotor defines a plurality of openings to receive permanent magnets near an outer portion of the rotor and a number of spokes interposed between mass reduction cutouts located closer to the center relative to the permanent magnets. Each of the permanent magnets defines a magnetic pole and each of the spokes is circumferentially aligned with one of the magnetic poles.

Claims

1. A propulsion system comprising:

a combustion engine;

a greater than 36 volts but less than 60 volts power source used to supply a traction electric machine; and

a starter electric machine selectively coupled to the engine for a restart and powered by the greater than 36 volts but less than 60 volts power source, the starter electric machine including;

a stator having a plurality of teeth disposed around a circumference oriented radially towards a center defining slots interposed between each of the teeth,

a conductive winding wrapped around each of the teeth of the stator to receive an electrical current, and

a rotor rotatable relative to the stator, the rotor defining a number of openings to receive permanent magnets near an outer portion of the rotor and a number of spokes interposed between mass reduction cutouts located closer to the center relative to the permanent magnets, wherein each of the permanent magnets defines a magnetic pole and each of the magnetic poles is circumferentially aligned with one of the spokes.

2. The engine starter system of claim 1 wherein the starter electric machine is selectively coupled to a flywheel of the engine to provide a cranking torque for an engine restart.

3. The engine starter system of claim 1 further comprising a controller programmed to synchronize a speed of the starter electric machine with a speed of the engine prior to engaging the starter electric machine of the engine.

4. The engine starter system of claim 1 wherein the starter electric machine is configured to be powered by the same greater than 36 volt power source as the traction electric machine.

5. The engine starter system of claim 1 wherein a ratio of an outer diameter of the stator to a lamination stack length is between about 1.5 and 3.5.

6. The engine starter system of claim 1 wherein an outer diameter of the stator is less than about 80 millimeters.

7. The engine starter system of claim 1 wherein a total number of magnetic poles is from 4 to 14 and a total number of slots of the stator is from 6 to 18.

8. The interior permanent magnet electric machine of claim 1 wherein each of the number of openings defined by the rotor is shaped to include air gaps on two sides of the respective permanent magnet, the rotor additionally including a first bridge portion configured to separate each of two adjacent air gaps and a second bridge portion configured to hold the outer portion of the rotor lamination to be a single piece.