Search

CA-3240709-C - ENERGY STORAGE POWER SOURCE USING A WOUND-ROTOR INDUCTION MACHINE (WRIM) TO CHARGE AND DISCHARGE ENERGY STORAGE ELEMENTS (ESES)

CA3240709CCA 3240709 CCA3240709 CCA 3240709CCA-3240709-C

Abstract

A stored energy power source uses a wound-rotor induction machine (WRIM) to receive energy from an external source, store the energy in N energy storage elements (ESEs) via tertiary windings, and discharge the ESEs to deliver energy via a secondary winding to a load producing output. Each discharging ESE contributes to a total flux at the secondary winding to sum the individual ESEs voltages. These voltages can be stepped up or down by a transformation ratio between the secondary winding and each of the tertiary windings. A flywheel may be coupled to the secondary to store and delivery energy. Load factor power control can be used to stabilize the output voltage. The source may be configured to allow for the bi-directional flow of energy between an external power source, the ESEs, the flywheel and the load.

Inventors

  • Stephen B. Kuznetsov

Assignees

  • RAYTHEON COMPANY

Dates

Publication Date
20260505
Application Date
20221220
Priority Date
20211221

Claims (20)

  1. 22 I CLAIM: 1. An energy storage power source, comprising: a machine input configured to receive a variable AC input voltage Vin at 5 a variable frequency; a wound-rotor induction machine (WRIM) including a primary winding that is wound 360 degrees around a first magnetic core and coupled to the machine input to receive the AC input voltage Vin, a secondary winding that is wound 360 degrees around a second magnetic core configured to rotate relative to the first 10 magnetic core and coupled to a load producing output and N tertiary windings each wound 360/N degrees and distributed around the first magnetic core and magnetically coupled to both the primary and secondary windings; N energy storage elements (ESEs); N bi-directional AC/DC converters that each couple one of the tertiary 15 windings to a respective one of the ESEs; and a WRIM controller, wherein in a charging state, the AC input voltage is coupled to the primary winding to create a traveling magnetic field to provide relative rotation between the first and second magnetic cores and to magnetize the 20 tertiary windings to provide power through the AC/DC converters to selectively charge one or more of the N ESEs; and wherein in a discharge state, one or more of the N ESEs discharge energy back through the respective AC/DC converters to excite the respective tertiary windings to create a traveling magnetic field to 25 magnetize an airgap to assist the relative rotation between the first and second magnetic cores and to individually contribute to a total machine magnetic flux to magnetize the secondary winding to induce an AC output voltage on the secondary winding proportional to the sum of the voltages from the discharging ESEs and deliver energy to the load producing 30 output.
  2. 2. The energy storage power source of claim 1, further comprising: an AC/AC converter that is configured to receive an AC voltage at a fixed frequency f1 from an external AC power source and convert that AC voltage into 23 the variable AC input voltage at variable frequency f2 at the machine input.
  3. 3. The energy storage power source of claim 1, further comprising: a DC/AC converter that is configured to receive a DC voltage from an external DC power source and convert that DC voltage 5 into the variable AC input voltage at variable frequency at the machine input.
  4. 4. The energy storage power source of claim 1, wherein the AC output voltage is scaled by a transformation ratio determined by turns ratios of the 10 secondary winding to the N tertiary windings.
  5. 5. The energy storage power source of claim 4, wherein the transformation ratio is on average for all N ESEs greater than 1:1 to increase the AC output voltage.
  6. 6. The energy storage power source of claim 1, wherein the load producing output is configured for a bi-directional flow of energy, wherein the WRIM is configured to selectively receive energy from the load producing output to charge the ESEs.
  7. 7. The energy storage power source of claim 6, further comprising: a flywheel coupled to the second magnetic core, said flywheel configured to selectively store energy from the AC input voltage, the ESEs or the load producing output via the secondary winding and to selectively deliver energy to 25 at least the ESEs and the load producing output via the secondary winding.
  8. 8. The energy storage power source of claim 6, wherein the machine input is configured for a bi-directional flow of energy, wherein the WRIM is configured to receive energy from the load producing output and deliver the energy back to 30 the machine input.
  9. 9. The energy storage power source of claim 1, wherein the N ESEs are electrically isolated from each other and the primary, secondary and N tertiary windings are electrically isolated from each other. 24
  10. 10. The energy storage power source of claim 1, wherein a primary-to-tertiary turns ratio Np/Nt(i) for i = 1 to N is independently configured to deliver a specified DC voltage VDC(i) to each of the N ESEs.
  11. 11. The energy storage power source of claim 1, wherein the N bi-directional AC/DC converters are independently controllable to selectively charge one or more ESEs exclusively or (XOR) independently controllable to selectively discharge the one or more ESEs.
  12. 12. The energy storage power source of claim 1, wherein the primary winding is segmented into M primary windings, each primary winding is coupled to a respective machine energy input to receive the AC input voltage, each primary winding is magnetically coupled to one or more of the tertiary windings, wherein 15 the WRIM controller is configurable to simultaneously charge one or more ESEs coupled to a first subset of the M primary windings and to discharge one or more ESEs coupled to a second subset of the M primary windings in which the first and second subsets do not overlap. 20
  13. 13. The energy storage power source of claim 1, further comprising: a load factor power controller coupled to the load producing output to modulate an inductive-resistive load to actively adjust a power factor of the WRIM to vary a rotational speed and maintain the AC output voltage within a specified tolerance of a target voltage.
  14. 14. The energy storage power source of claim 1, further comprising: a flywheel coupled to the second magnetic core to store energy and to deliver kinetic energy to the ESEs or the load producing output.
  15. 15. The energy storage power source of claim 14, wherein the WRIM controller is configured to discharge one or more ESEs to deliver energy to the load producing output with a first time constant and decelerate the flywheel to deliver energy to the load producing output at a second time constant wherein the second time constant is longer th 5 an said first time constant.
  16. 16. The energy storage power source of claim 1, wherein in the discharging state the WRIM controller is configured to selectively decouple the AC input voltage from the primary winding.
  17. 17. The energy storage power source of claim 1, wherein in the discharging state the WRIM controller is configured to leave the AC input voltage coupled to the primary winding to deliver additional energy via the secondary winding to the load producing output.
  18. 18. An energy storage power source, comprising: a machine input configured to receive a variable AC input voltage Vin at a variable frequency; a wound-rotor induction machine (WRIM) including a primary winding 20 that is wound 360 degrees around a first magnetic core and coupled to the machine input to receive the AC input voltage Vin, a secondary winding that is wound 360 degrees around a second magnetic core configured to rotate relative to the first magnetic core and coupled to a load producing output and N tertiary windings each wound 360/N degrees and distributed around the first magnetic core and 25 magnetically coupled to both the primary and secondary windings, wherein a turns ratio of a number of secondary turns Ns to a number of tertiary turns Nt(i) i = 1 to N defines an average step-up transformation ratio greater than one; a flywheel mechanically coupled to the second magnetic core; N energy storage elements (ESEs) that are electrically isolated from each 30 other; N bi-directional AC/DC converters that each couple one of the tertiary winding to a respective one of the ESEs; and a WRIM controller, 26 wherein in one or more charging states, the AC input voltage is coupled to the primary winding to create a traveling magnetic field to provide the relative rotation between the first and second magnetic cores and to magnetize the tertiary windings to provide power through the AC/DC converters to selectively charge one 5 or more of the N ESEs or to magnetize the secondary winding and create torque to charge the flywheel; and wherein in one or more discharge states, one or more of the N ESEs discharge back through the respective AC/DC converters to excite the 10 respective tertiary windings to create a traveling magnetic field to magnetize an airgap to assist the relative rotation between the first and second magnetic cores and to individually contribute to a total machine magnetic flux to magnetize the secondary winding to induce an AC output voltage on the secondary winding proportional to the sum of the voltages 15 from the discharging ESEs multiplied by the respective step-up transformation ratios and deliver the energy to the load producing output or the flywheel discharges energy through the secondary winding to the load producing output. 20
  19. 19. An energy storage power source, comprising: a wound-rotor induction machine (WRIM) including N tertiary windings each wound 360/N degrees and distributed around a first magnetic core and a secondary winding that is wound 360 degrees around a second magnetic core configured to rotate relative to the first magnetic core and coupled to a load 25 producing output; N energy storage elements (ESEs); N bi-directional AC/DC converters that each couple one of the tertiary winding to a respective one of the energy storage elements; a WRIM controller, 30 wherein in a charging state, an external power source is coupled to the WRIM to create a traveling magnetic field to provide the relative rotation between the first and second magnetic cores and to magnetize the tertiary windings to provide power through the AC/DC converters to selectively charge the N ESEs; and 27 wherein in a discharge state, one or more of the N energy storage elements discharging back through the AC/DC converters are used to excite the tertiary windings to create a traveling magnetic field to magnetize an airgap to assist the relative rotation between the first and second magnetic cores and to individually c 5 ontribute to a total machine magnetic flux to magnetize the secondary winding to induce an AC output voltage on the secondary winding proportional to the sum of the voltages from the discharging energy storage elements and deliver the energy to the load producing output.
  20. 20. The energy storage power source of claim 19, wherein the voltages from the discharging ESEs are multiplied by respective transformation ratios associated with turns ratios of the secondary winding to the respective tertiary windings and summed to deliver the energy to the load producing output, wherein the N ESEs 15 are electrically isolated from each other, wherein energy flows bi-directionally at each of the N ESEs and the load producing output.

Description

1 ENERGY STORAGE POWER SOURCE USING A WOUND-ROTOR INDUCTION MACHINE (WRIM) TO CHARGE AND DISCHARGE ENERGY STORAGE ELEMENTS (ESEs) CLAIM OF PRIORITY This patent application claims the benefit of priority to U.S. Application Serial No. 17/557,758, filed December 21, 2021. BACKGROUND OF THE INVENTION Field of the Invention This invention relates to energy storage power sources that receive and store power from an external source and deliver the energy to a load, and more 15 particularly to the use of a wound-rotor induction machine (WRIM) to receive energy from an external source, store the energy in N energy storage elements (ESEs), and discharge the ESEs to deliver energy to a load producing output. The WRIM provides a safe, reliable and efficient system to provide high-level AC and DC output voltages. Description of the Related Art Energy storage power sources receive and store energy from an external power source, AC or DC, and when needed deliver the power to a load. These types of energy storage power sources store energy in a number of individual 25 storage cells such as batteries, high-density capacitors or fuel cells. With current technology, each of these cells is limited to produce approximately 2-3 Volts DC. To deliver a high DC output voltage e.g., 1,000 Volts to the load may require connecting 500 storage cells in series across the load. The practical drawbacks include size, weight, reliability and decrease in efficiency as 30 individual cells age, and safety considerations. As shown in Figure 1, an energy storage power source 10 includes an AC power source 12 such as may be provided by a utility’s power grid that provide an AC input voltage via an AC main bus 14. To support the charging of N storage cells 16, A like plurality of step-down transformers 18 and AC/DC 35 rectifiers 20 step the AC input voltage down and convert it to a usable voltage WO 2023/122084 PCT/0S2022/053501 e.g. 2-3 V DC, to charge each of the N storage cells 16. The storage cells 16 are interconnected via contactors 22 that when CLOSED provide a series connection of all of the storage cells 16 to sum their individual voltages to provide a higher DC output voltage 24 across a load 26. A voltage equalizing network (VEN) 28 is connected across each of the storage cells 16. Each VEN 26 includes a first switch QI in series with a resistor RI to help balance differences in storage cell terminal voltages among the group of N storage cells. Each VEN 26 also includes a second switch Q2 in parallel with Q2/Rl that acts as a bypass should a particular storage cell 16 fail. Because of size, weight, reliability, loss of efficiency and safe considerations this approach becomes impractical when the number of storage cells is larger e.g, sufficient to provide a DC output voltage of 1,000 V. SUMMARY OF THE INVENTION The following is a summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description and the defining 20 claims that are presented later. The present invention provides a stored energy power source that uses a wound-rotor induction machine (WRIM) to receive energy from an external source, store the energy in N energy storage elements (ESEs), and discharge the ESEs to deliver energy to a load producing output. The WRIM provides a safe, 25 reliable and efficient system to provide high-level AC and DC output voltages. In an embodiment, the WRIM includes N tertiary windings each wound 360/N degrees and distributed around a first magnetic core and a secondary (e.g., rotor) winding that is wound 360 degrees around a second magnetic core configured to rotate relative to the first magnetic core and coupled to a load 30 producing output. N bi-directional AC/DC converters couple each of the tertiary windings to a respective energy storage element (ESE). Each ESE includes one or more series-connected storage cells such as a battery, high-density capacitor or fuel cell. In a charging state, a WRIM controller couples an external energy source to the WRIM to create a traveling magnetic field to provide the 2 WO 2023/122084 PCT/0S2022/053501 relative rotation between the first and second magnetic cores (e.g., stationary stator magnet and rotating rotor magnet) and to magnetize the tertiary windings to provide power through the AC/DC converters to selectively charge the N ESEs. In a discharge state, the WRI controller discharges at least some of the N energy 5 storage elements back through the AC/DC converters to excite the tertiary windings to create a traveling magnetic field to magnetize an airgap to assist the relative rotation between the first and second magnetic cores and to individually contribute to a total flux to magnetize the secondary winding to