ELECTRIC MACHINE FOR HYBRID POWERTRAIN WITH DUAL VOLTAGE POWER SYSTEM

• US 20170057373A1
• Filed: 06/28/2016
• Published: 03/02/2017
• Est. Priority Date: 08/24/2015
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Nehl, Thomas W., Hao, Lei, Namuduri, Chandra S.
• Granted Patent: US 9,925,889 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: H02K 1/2766 having a flux concentration effect
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence
• CPC Class Codes: H02K 21/14 with magnets rotating within the armatures
• CPC Class Codes: H02K 3/28 Layout of windings or of connections between windings windings for pole-changing H02K17/06, H02K17/14, H02K19/12, H02K19/32
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

An electric machine is provided for a dual voltage power system having a first energy storage system (HV-ESS) with a first nominal voltage and second energy storage system (LV-ESS with a second nominal voltage). The electric machine includes a rotor assembly having a rotor core configured to support permanent magnets spaced around the rotor core to define a number of rotor poles. The rotor core has multiple rotor slots arranged as at least one barrier layer at each of the rotor poles. Permanent magnets are disposed in the at least one barrier layer. A stator assembly surrounds the rotor assembly. The electric machine is configured to be operatively connected with the HV-ESS. The electric machines has at least one of a predetermined efficiency at rated power, a predetermined power density, a predetermined torque density, a predetermined peak power range, or a predetermined maximum speed of the electric machine.

Claims

1. An electric machine for a dual voltage power system having a first energy storage system (HV-ESS) with a first nominal voltage and second energy storage system (LV-ESS) with a second nominal voltage, the electric machine comprising:

a rotor assembly having a rotor core configured to support permanent magnets spaced around the rotor core to define a number of rotor poles;

wherein the rotor core has multiple rotor slots arranged as at least one barrier layer at each of the rotor poles;

wherein the at least one barrier layer is positioned between an inner periphery of the rotor core and an outer periphery of the rotor core;

permanent magnets disposed in the at least one barrier layer;

a stator assembly surrounding the rotor assembly;

wherein the electric machine is configured to be operatively connected with the HV-ESS to function as at least one of a motor and a generator; and

wherein the rotor assembly, the stator assembly, and the magnets are configured with parameters selected to provide at least one of a predetermined efficiency at rated power, a predetermined power density, a predetermined torque density, a predetermined peak power range, or a predetermined maximum speed of the electric machine.

2. The electric machine of claim 1, further comprising:

a motor controller power inverter module (MPIM) operatively connected to the stator assembly.

3. The electric machine of claim 2, in combination with:

an engine having a crankshaft operatively connected with the electric machine;

the dual voltage power system including;

the HV-ESS operatively connected to the stator assembly and to a relatively high voltage electric load;

the LV-ESS operatively connected to a relatively low voltage electrical load;

a DC-DC converter operatively connected to both the HVV-ESS and the LV-ESS;

wherein the MPIM is configured to control the electric machine to achieve a motoring mode in which the electric machine adds torque to the crankshaft using stored electrical power from the HV-ESS;

wherein the MPIM is configured to control the electric machine to supply power to the relatively high voltage loads via the HESS and to supply power to the relatively low voltage loads through the DC-DC converter and the LV-ESS.

4. The electric machine of claim 1, wherein the at least one barrier layer includes a first barrier layer with two adjacent and discontinuous segments spaced apart from one another by a bridge of the rotor core, and arranged in a V-formation.

5. The electric machine of claim 4, wherein the at least one barrier layer includes:

a second barrier layer positioned between the first barrier layer and an outer periphery of the rotor core.

6. The electric machine of claim 5, wherein the second barrier layer is a single slot.

7. The electric machine of claim 5, wherein the second barrier layer includes two adjacent and discontinuous segments spaced apart from one another and arranged in a V-formation.

8. The electric machine of claim 5, wherein the magnets are only in the first barrier layer.

9. The electric machine of claim 5, wherein the magnets are in both the first barrier layer and the second barrier layer.

10. The electric machine of claim 1, wherein the stator assembly has a number of stator slots circumferentially-spaced around the stator assembly and configured to support stator windings;

wherein the number of rotor poles is 8 and the number of stator slots is 60.

11. The electric machine of claim 1, wherein the stator assembly has a number of stator slots circumferentially-spaced around the stator assembly and configured to support stator windings;

wherein the number of rotor poles is 8 and the number of stator slots is 60.

12. The electric machine of claim 1, wherein the magnets are a dysprosium (Dy)-reduced material with a maximum energy product from about 33 mega Gauss Oersteds (MGOe) to about 48 MGO and are configured to saturate a bridge of the rotor core between the at least one barrier layer and the outer periphery of the rotor core.

13. The electric machine of claim 1, wherein the predetermined efficiency is at least 85 percent efficiency over 2500 revolutions per minute (rpm) to 7000 rpm for power from 1500 watts to 12000 watts, the predetermined peak power density is 4 kilowatts per liter (kW/L), the predetermined peak torque density is 18 Newton-meters per liter (Nm/L), the predetermined peak power range is 10 kilowatts (kW) from 4500 rpm to 6000 rpm, and the predetermined maximum speed is at least 18,000 rpm.

14. The electric machine of claim 1, wherein the stator assembly has at least three electrical phases, and the number of turns in electrical windings per each of said electrical phases is not less than 12 and not more than 32.

15. The electric machine of claim 1, wherein the stator assembly has multiple axially-stacked stator laminations;

and

wherein a ratio of an outer diameter of the stator laminations to an axial length of the stator laminations is not less than 2.0 and not greater than 3.5.

16. The electric machine of claim 15, wherein the outer diameter of the stator laminations is not greater than 155 millimeters and the axial length of the stator laminations is not greater than 60 millimeters.

17. The electric machine of claim 1, wherein a short circuit current over an entire speed range of the electric machine is not less than 0.6 and not more than 0.9 multiplied by a rated current of the electric machine.

18. The electric machine of claim 1, wherein a normalized flux linkage at a peak torque of the electric machine is greater than 0.7.

19. The electric machine of claim 1, wherein a saliency ratio of the electric machine at a rated torque of the electric machine is not less than 1.5 and not greater than 3.0.

20. A powertrain comprising:

an electric machine having a rotor assembly with permanent magnets, a stator assembly, and a motor controller power inverter module (MPIM) operatively connected to the stator assembly;

an engine having a crankshaft operatively connected with the electric machine by a belt drive train;

a dual voltage power system having;

a first energy storage system (HV-ESS) with a first nominal voltage;

a second energy storage system (LV-ESS) with a second nominal voltage);

a DC-DC converter operatively connected to both the HV-ESS and the LV-ESS;

a first electric load operatively connected with the HV-ESS;

a second electrical load operatively connected with the LV-ESS;

wherein the MPIM is configured to control the stator assembly to achieve a motoring mode in which the electric machine adds torque to the crankshaft using stored electrical power from the HV-ESS;

wherein the MPIM is configured to control the stator assembly to supply power to the relatively high voltage loads via the HESS and to supply power to the relatively low voltage loads through the DC-DC converter and the LV-ESS;

wherein the rotor assembly has a rotor core configured to support permanent magnets spaced around the rotor core to define a number of rotor poles;

wherein the rotor core has multiple rotor slots arranged as at least one barrier layer at each of the rotor poles;

wherein the at least one barrier layer is positioned between an inner periphery of the rotor core and an outer periphery of the rotor core;

wherein the permanent magnets are disposed in the at least one barrier layer;

wherein the stator assembly surrounds the rotor assembly; and

wherein the rotor assembly, the stator assembly, and the magnets are configured with parameters selected to provide at least one of a predetermined efficiency at rated power, a predetermined power density, a predetermined torque density, a predetermined peak power range, or a predetermined maximum speed of the electric machine.