Hybrid vehicle engine starter systems and methods

• US 10,293,804 B2
• Filed: 05/19/2016
• Issued: 05/21/2019
• 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: Namuduri, Chandra S., Hao, Lei, Gopalakrishnan, Suresh, Nehl, Thomas W.
• Primary Examiner(s): Worden, Thomas E
• Application Number:
  US15/159,070
• Publication Number:
  US 20170334422A1
• Time in Patent Office: 1,097 Days
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 2006/4825 Electric machine connected or connectable to gearbox input shaft
• CPC Class Codes: B60K 6/26 characterised by the motors or the generators
• CPC Class Codes: B60K 6/442 Series-parallel switching type
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• CPC Class Codes: B60W 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60Y 2200/92 Hybrid vehicles
• CPC Class Codes: B60Y 2300/182 Selecting between different operative modes, e.g. comfort and performance modes
• CPC Class Codes: B60Y 2300/192 Power-up or power-down of the driveline, e.g. start up of a cold engine
• CPC Class Codes: B60Y 2300/43 Control of engines
• CPC Class Codes: B60Y 2300/60 Control of electric machines, e.g. problems related to electric motors or generators
• CPC Class Codes: B60Y 2300/63 Starter motor mode
• CPC Class Codes: B60Y 2400/60 Electric Machines, e.g. motors or generators
• CPC Class Codes: F02N 11/00 Starting of engines by means of electric motors
• CPC Class Codes: F02N 11/006 using a plurality of electric motors
• CPC Class Codes: F02N 11/0814 comprising means for controlling automatic idle-start-stop
• CPC Class Codes: F02N 11/0862 : characterised by the electrical power supply means, e.g. battery
• CPC Class Codes: F02N 2200/101 : Accelerator pedal position
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y10S 903/906 : Motor or generator
• CPC Class Codes: Y10S 903/93 : Conjoint control of different elements

Abstract

A vehicle propulsion system includes an engine and a first electric machine each configured to selectively provide torque to propel the vehicle. The propulsion system also includes a second electric machine coupled to the engine and configured to start the engine from an inactive state. A high-voltage battery powers both of the first electric machine and the second electric machine over a high-voltage bus. The vehicle further includes a controller programmed to issue a command to start the engine using the second electric machine in response to a threshold acceleration demand following a period of reduced acceleration demand.

Claims

1. A vehicle propulsion system for a vehicle, the vehicle propulsion system comprising:

an engine and a first electric machine each configured to selectively provide torque to propel the vehicle;

a second electric machine coupled to the engine and configured to start the engine from an inactive state;

wherein the second electric machine is a brushless permanent magnet motor having a housing;

wherein the brushless permanent magnet motor includes a rotor with a hollow center portion, has an output torque of 2.5 Newton-meters at 16,000 revolutions per minute, and has an inertia value of 1.205×

10<sup>−

4</sup> kilograms-square meter;

a high-voltage battery to power both of the first electric machine and the second electric machine over a high-voltage bus;

wherein the high-voltage battery has an operating voltage of at least 30 volts;

an inverter integrated as a circuit within the housing and having a plurality of solid-state switches independently and selectively connectable to the high-voltage battery and operable to convert direct current from the high-voltage battery to alternating current to drive the brushless permanent magnet motor;

a bi-directional DC-DC converter;

a low-voltage battery configured to power at least one vehicle accessory over a low-voltage bus;

wherein the low-voltage battery is operatively connected to the high-voltage battery via the bi-directional DC-DC converter and is operable to provide electrical power to the high-voltage battery via the bi-directional DC-DC converter;

wherein only the high-voltage bus and not the low-voltage bus is connected to the second electric machine so that only the high-voltage battery and not the low-voltage battery provides electrical power to the second electric machine to start the engine; and

a controller operatively connected to the inverter and programmed to issue a command to start the engine using the second electric machine in response to a threshold acceleration demand following a period of reduced acceleration demand.

2. The vehicle propulsion system of claim 1 wherein the high-voltage battery has a nominal voltage of 48 volts.

3. The vehicle propulsion system of claim 1 wherein the low-voltage battery is configured to power at least one vehicle accessory over the low-voltage bus.

4. The vehicle propulsion system of claim 1 wherein the controller is further programmed to deactivate the engine in response to a coast condition corresponding to substantially zero acceleration demand while the vehicle is moving.

5. The vehicle propulsion system of claim 1 wherein the second electric machine is provided with a single solenoid actuator to selectively, mechanically couple the second electric machine to the engine, and the second electric machine is selectively, electrically connected to the high-voltage battery via the solid-state switches.

6. The vehicle propulsion system of claim 1 wherein the engine is configured to be deactivated during a vehicle rolling coast condition.

7. The vehicle propulsion system of claim 1, wherein the engine and the second electric machine are each configured to selectively provide torque to a single set of vehicle wheels.

8. A vehicle propulsion system for a vehicle, the vehicle propulsion system comprising:

a high-voltage battery;

wherein the high-voltage battery has an operating voltage of at least 30 volts;

an electric machine capable of selectively propelling the vehicle using power from the high-voltage battery;

an engine capable of selectively propelling the vehicle;

a brushless permanent magnet starter motor having a housing;

wherein the brushless permanent magnet starter motor is directly coupled to and powered by the high-voltage battery over a high-voltage bus and is configured to couple to the engine and restart the engine from a deactivated state;

wherein the brushless permanent magnet starter motor includes a rotor with a hollow center portion, has a power output of 4200 Watts at 16,000 revolutions per minute, and has an inertia value of 1.205×

10<sup>−

4</sup> kilograms-square meter;

an inverter integrated as a circuit within the housing and having a plurality of solid state switches independently and selectively connectable to the high-voltage battery and operable to convert direct current from the high-voltage battery to alternating current to drive the brushless permanent magnet starter motor;

a bi-directional DC-DC converter;

a low-voltage battery configured to power at least one vehicle accessory over a low-voltage bus;

wherein the low-voltage battery is operatively connected to the high-voltage battery via the bi-directional DC-DC converter and is operable to provide electrical power to the high-voltage battery via the bi-directional DC-DC converter;

wherein only the high-voltage bus and not the low-voltage bus is connected to the brushless permanent magnet starter motor so that only the high-voltage battery and not the low-voltage battery provides electrical power to the brushless permanent magnet starter motor to start the engine; and

a controller programmed to

deactivate the engine in response to an acceleration demand less than a first threshold,

operate the brushless permanent magnet starter motor in response to an acceleration demand greater than a second threshold while the engine is in a deactivated state,

synchronize a speed of the brushless permanent magnet starter motor with a speed of the engine, and

engage the brushless permanent magnet starter motor with the engine to restart the engine.

9. The vehicle propulsion system of claim 8 wherein the controller is further programmed to deactivate the engine in response to a coast condition corresponding to substantially zero acceleration demand while the vehicle is rolling.

10. The vehicle propulsion system of claim 8 wherein the controller is further programmed to deactivate the engine in response to a standstill condition corresponding to substantially zero acceleration demand.

11. The vehicle propulsion system of claim 8 wherein the second threshold is greater than the first threshold.

12. The vehicle propulsion system of claim 8 wherein the brushless permanent magnet starter motor is provided with a single solenoid actuator to selectively couple the brushless permanent magnet starter motor to the engine.

13. The vehicle propulsion system of claim 8 further comprising a rotor position sensor operable to sense a rotational position of the rotor of the brushless permanent magnet starter motor.

14. A system comprising:

an engine and an electric machine each configured to selectively provide torque;

a brushless permanent magnet starter motor coupled to the engine and configured to start the engine from an inactive state;

wherein the brushless permanent magnet starter motor includes a rotor with a hollow center portion, has an output torque of 2.5 Newton-meters at 16,000 revolutions per minute, and has an inertia value of 1.205×

10<sup>−

4</sup> kilograms-square meter; and

a high-voltage battery to power both of the electric machine and the brushless permanent magnet starter motor only over a high-voltage bus;

wherein the high-voltage battery has an operating voltage of at least 30 volts.

15. A system comprising:

an engine and a first electric machine each configured to selectively provide torque;

a second electric machine coupled to the engine and configured to start the engine from an inactive state;

wherein the second electric machine is a brushless permanent magnet starter motor;

wherein the second electric machine includes a rotor with a hollow center portion, has a power output of 4200 Watts at 16,000 revolutions per minute, and has an inertia value of 1.205×

10<sup>−

4</sup> kilograms-square meter;

a high-voltage battery to power both of the first electric machine and the second electric machine over a high-voltage bus;

wherein the high-voltage battery has an operating voltage of at least 30 volts;

a bi-directional DC-DC converter;

a low-voltage battery configured to power at least one vehicle accessory over a low-voltage bus;

wherein the low-voltage battery is operatively connected to the high-voltage battery via the bi-directional DC-DC converter and is operable to provide electrical power to the high-voltage battery via the bi-directional DC-DC converter;

wherein only the high-voltage battery and not the low-voltage battery provides electrical power to the second electric machine to start the engine; and

a controller programmed to issue a command to start the engine using the second electric machine.