Modular electric power generating system with multistage axial flux generator

• US 10,483,886 B2
• Filed: 09/14/2017
• Issued: 11/19/2019
• Est. Priority Date: 09/14/2017
• Status: Active Grant

• Current Assignee: Hamilton Sundstrand Corporation (Rtx Corporation)
• Original Assignee: Hamilton Sundstrand Corporation (Rtx Corporation)
• Inventors: Rozman, Gregory I., Gieras, Jacek F., Moss, Steven J.
• Primary Examiner(s): Patel, Tulsidas C
• Assistant Examiner(s): Ortega, Joseph
• Application Number:
  US15/704,531
• Publication Number:
  US 20190081582A1
• Time in Patent Office: 796 Days
• CPC Class Codes: B60L 50/10 using propulsion power supplied by engine-driven generators, e.g. generators driven by combustion engines
• CPC Class Codes: B60L 50/12 using AC generators and DC motors
• CPC Class Codes: B60L 50/13 using AC generators and AC motors
• CPC Class Codes: H02H 7/062 for parallel connected generators
• CPC Class Codes: H02J 1/106 for load balancing, symmetrisation, or sharing
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: H02J 7/143 with multiple generators
• CPC Class Codes: H02K 16/00 Machines with more than one rotor or stator machines for transmitting mechanical power from a driving shaft to a driven shaft and comprising structurally interrelated motor and generator parts H02K51/00; permanent magnet machines with multiple rotors or stators relatively rotated for vectorially combining the excitation fields or the armature voltages H02K21/029
• CPC Class Codes: H02K 16/04 Machines with one rotor and two stators
• CPC Class Codes: H02K 21/24 with magnets axially facing the armatures, e.g. hub-type cycle dynamos
• CPC Class Codes: H02K 7/1807 Rotary generators H02K7/006 takes precedence
• CPC Class Codes: H02M 5/4585 having a rectifier with controlled elements
• CPC Class Codes: H02M 7/2173 in a biphase or polyphase circuit arrangement H02M7/2176 takes precedence; voltage multipliers H02M7/25
• CPC Class Codes: H02M 7/23 arranged for operation in parallel H02M7/2176 takes precedence
• CPC Class Codes: H02P 2103/20 of the synchronous type
• CPC Class Codes: H02P 2201/03 AC-DC converter stage controlled to provide a defined DC link voltage
• CPC Class Codes: H02P 9/006 Means for protecting the generator by using control control effected upon generator excitation circuit to reduce harmful effects of overloads or transients H02P9/10
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors

Abstract

An example electrical power system includes a DC bus connected to a load, a plurality of generators driven by rotation of a common shaft, and a plurality of power converters. Each power converter includes an active rectifier controller that operates a respective active rectifier to rectify AC from a respective one of the generators to DC on the DC bus. A load sharing controller is operable to provide a respective adjustment signal to each respective power converter that is enabled, the respective adjustment signals based on a difference between an average output current across all of the active rectifiers that are enabled, and a particular output current of the respective power converter. Each active rectifier controller is operable to determine a quadrature current value for its associated generator based on its adjustment signal.

Claims

1. An electrical power system comprising:

a direct current (DC) bus connected to a load;

a plurality of generators driven by rotation of a common shaft;

a plurality of power converters, each comprising an active rectifier controller that operates a respective associated one of a plurality of active rectifiers to rectify multi-phase alternating current (AC) from a respective associated one of the plurality of generators to DC on the DC bus; and

a load sharing controller operable to provide a respective corrective signal to each respective power converter that is enabled, the respective corrective signals based on a difference between an average output current across all of the active rectifiers that are enabled, and a particular output current of the respective power converter;

wherein each active rectifier controller is operable to determine a quadrature current value for the generator associated with the active rectifier controller based on the corrective signal provided to the power converter of the active rectifier controller, and control the active rectifier associated with the active rectifier controller based on the quadrature current value.

2. The electrical power system of claim 1, comprising:

an output filter situated on the DC bus between the load and a node that connects each of the plurality of active rectifiers that are enabled to the DC bus.

3. The electrical power system of claim 2, wherein the output filter comprises a first filter portion on a positive rail of the DC bus, and a second filter portion on a negative rail of the DC bus, each of the first and second filter portions comprising a first inductor and a second inductor, the first inductor connected in parallel with a resistor between first and second nodes, and the second inductor connected in series to the first node.

4. The electrical power system of claim 1:

wherein the corrective signal comprises a first quadrature current; and

wherein each active rectifier controller is configured to;

determine a second quadrature current based on feedback current values from each phase of the generator associated with the active rectifier controller;

determine a third quadrature current based on a rotational speed of the common shaft and a difference between a DC bus voltage and an output voltage of the active rectifier associated with the active rectifier controller;

determine the quadrature current value based on the first, second, and third quadrature currents; and

determine a target output voltage for the active rectifier associated with the active rectifier controller based on the quadrature current value.

5. The electrical power system of claim 1:

wherein the corrective signal comprises a reference voltage; and

wherein each active rectifier controller is configured to;

determine a first quadrature current based on feedback current values from each phase of the generator associated with the active rectifier controller;

determine a second quadrature current based on a rotational speed of the common shaft and a difference between the reference voltage and an output voltage of the active rectifier associated with the active rectifier controller;

determine the quadrature current value based on the first and second quadrature currents; and

determine a target output voltage for the active rectifier associated with the active rectifier controller based on the quadrature current value.

6. The electrical power system of claim 1, wherein each active rectifier controller is operable to disable the active rectifier associated with the active rectifier controller based on a detected fault condition in the generator associated with the active rectifier controller.

7. The electrical power system of claim 6, wherein to disable the active rectifier associated with the active rectifier controller, the active rectifier controller is configured to disconnect the active rectifier from at least one of a positive rail and a negative rail of the DC bus.

8. The electrical power system of claim 1, wherein each active rectifier controller is operable to:

utilize a carrier signal to perform pulse width modulation on the active rectifier associated with the active rectifier controller; and

phase shift the respective carrier signal of the active rectifier controller relative to the other active rectifiers based on a quantity of the power converters that are enabled.

9. The electrical power system of claim 1, wherein the plurality of active rectifiers are connected in parallel to each other on the DC bus.

10. The electrical power system of claim 1, comprising a prime mover engine that rotates the common shaft.

11. The electrical power system of claim 1, wherein each generator is an axial flux permanent magnet generator.

12. A method of operating an electrical power system, comprising:

driving a plurality of generators through rotation of a common shaft;

operating a plurality of power converters, each comprising an active rectifier, to rectify multi-phase alternating current (AC) from a respective one of the generators to direct current (DC) on a DC bus that powers a DC load;

performing load sharing amongst the plurality of power converters by providing a respective corrective signal to each respective power converter that is enabled, the respective corrective signals based on a difference between an average output current across all of the active rectifiers that are enabled, and a particular output current of the respective power converter; and

determining a quadrature current value for the generator associated with each power converter based on the corrective signal provided to the power converter; and

controlling each active rectifier that is enabled based on the quadrature current value of the active rectifier.

13. The method of claim 12, wherein the corrective signal comprises a first quadrature current, the method comprising, for each power converter:

determining a second quadrature current based on feedback current values from each phase of the generator associated with the power converter;

determining a third quadrature current based on a rotational speed of the common shaft and a difference between a DC bus voltage and an output voltage of the active rectifier associated with the power converter; and

determining the quadrature current value for the active rectifier of the power converter based on the first, second, and third quadrature currents; and

determining a target output voltage for the active rectifier of the power converter based on the quadrature current value.

14. The method of claim 13, wherein disabling an active rectifier comprises disconnecting the active rectifier from at least one of a positive rail and a negative rail of the DC bus.

15. The method of claim 12, wherein the corrective signal comprises a reference voltage, the method comprising, for each power converter:

determining a first quadrature current based on feedback current values from each phase of its associated generator;

determining a second quadrature current based on a rotational speed of the common shaft and a difference between a the reference voltage and an output voltage of the active rectifier associated with the power converter;

determining the quadrature current value for the active rectifier of the power converter based on the first and second quadrature currents; and

determining a target output voltage for the active rectifier of the power converter based on the quadrature current value.

16. The method of claim 12, comprising:

detecting a fault condition on a given one of the generators; and

disabling the active rectifier associated with the given generator based on said detecting.

17. The method of claim 12, comprising:

phase shifting respective pulse width modulation carrier signals of the active rectifiers relative to each other based on a quantity of the active rectifiers that are enabled.

18. The method of claim 17, wherein each power converter comprises a plurality of switching legs, each controlling connection of a respective stator winding of the generator associated with the power converter to the DC bus, the method comprising:

performing pulse width modulation on the plurality of switching legs based on the carrier signal.

19. The method of claim 12, comprising:

filtering an output of the plurality of active rectifiers that are enabled through a shared output filter that is situated on the DC bus between the load and the plurality of active rectifiers, the shared filter comprising a first filter portion on a positive rail of the DC bus, and a second filter portion on a negative rail of the DC bus, each of the first and second filter portions comprising a pair of inductors, one of which is connected in parallel with a resistor between first and second nodes, and the other which is connected in series to the first node.

20. The method of claim 12, wherein said driving a plurality of generators through rotation of a common shaft comprises:

operating a prime mover engine to rotate the common shaft.