Controller for a power train

• US 20040222639A1
• Filed: 04/30/2004
• Published: 11/11/2004
• Est. Priority Date: 05/06/2003
• Status: Active Grant

• Current Assignee: Nidec S R Drives Ltd (Nidec Corporation)
• Original Assignee: Switched Reluctance Drives Limited (Nidec Corporation)
• Inventors: Turner, Michael James, Sykes, Paul Andrew
• Granted Patent: US 7,091,627 B2
• Time in Patent Office: Days
• US Class Current: 290/3
• CPC Class Codes: B60K 6/26 characterised by the motors or the generators
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60L 2220/18 Reluctance machines
• CPC Class Codes: B60L 7/08 Controlling the braking effect B60L7/04, B60L7/06 take precedence
• CPC Class Codes: B60L 7/20 Braking by supplying regenerated power to the prime mover of vehicles comprising engine-driven generators
• 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 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A power train controller can operate in either motoring or braking modes. Its prime mover accepts a limited proportion of braking power and the remainder of the braking power is dissipated in an energy dump. A control system is arranged to maintain the voltage bus of the power train at a constant value throughout both modes.

Claims

1. A controller for a power train which includes a prime mover, a first electrical machine mechanically connected to the prime mover, a second electrical machine electrically connected to the first electrical machine by a voltage bus, and dissipation means connected to the voltage bus for dissipating electrical power, the controller comprising:

means for providing a speed signal indicative of a speed of the prime mover; and

first control means responsive to the speed signal to divert power generated by either the first or second electrical machine from the bus to the dissipation means.

2. A controller as claimed in claim 1, in which the means for providing the speed signal is operable to produce the speed signal when the speed of the prime mover reaches a threshold.

3. A controller as claimed in claim 1 in which the first control means is enabled by the speed signal to maintain the bus voltage substantially at a desired level by diverting power from the bus to the dissipation means in both motoring and braking modes of the second electrical machine.

4. A controller as claimed in claim 1, including switch means actuatable by the first control means for controlling the flow of power to the dissipation means.

5. A controller as claimed in claim 1 in which the first control means includes an error signal representing a difference between a desired speed and an actual speed of the prime mover above the desired speed, the first control means being operable to divert power to the dissipation means in accordance with the error signal.

6. A controller as claimed in claim 5 in which the first control means is operable to divert power to the dissipation means according to a control law function of the speed of the prime mover.

7. A controller as claimed in claim 6 in which the control law function is a proportional/integral/derivative function.

8. A method of controlling the voltage of a voltage bus of a power train which includes a prime mover, a first electrical machine mechanically connected to the prime mover, a second electrical machine electrically connected to the first electrical machine by the voltage bus and dissipation means connected to the voltage bus for dissipating electrical power, the method comprising:

providing a speed signal indicative of a speed of the prime mover; and

diverting power generated by either the first or second electrical machine from the bus to the dissipation means in response to the speed signal.

9. A method as claimed in claim 8 in which the speed signal is produced when the speed of the prime mover reaches a threshold.

10. A method as claimed in claim 8 including enabling maintenance of the bus voltage substantially at a desired level in accordance with the speed signal by diverting power from the bus to the dissipation means in both motoring and braking modes of the second electrical machine.

11. A method as claimed in claim 8, including actuating switch means for controlling the flow of power to the dissipation means.

12. A method as claimed in claim 8 including using feedback indicative of the voltage on the bus to control the bus voltage by diverting power to the dissipation means.

13. A method as claimed in claim 8 including generating an error signal which represents a difference between a desired speed and an actual speed of the prime mover above the desired speed, and diverting power to the dissipation means in accordance with the error signal.

14. A method as claimed in claim 13 in which power is diverted to the dissipation means according to the speed of the prime mover.

15. A power train system comprising a prime mover operable to provide and absorb mechanical power, a voltage bus, a first electrical machine operable as a generator to generate electrical power onto the voltage bus from the power delivered by the prime mover, and as a motor to deliver mechanical power absorbed by the prime mover;

at least one second electrical machine connected to the voltage bus and operable to be driven by the electrical power generated by the first electrical machine and as a generator to deliver electrical power onto the voltage bus to drive the first electrical machine;

dissipation means for dissipating electrical power from the voltage bus;

means for providing a speed signal indicative of the speed of the prime mover; and

a controller responsive to the speed signal and the voltage on the bus to divert power from the bus to the dissipation means to maintain the bus voltage at a substantially constant level.