Common monitoring and/or control of a flywheel and battery-based power supply system

1. A power supply system for supplying back-up power to a load, where the load is powered by power from an alternating current (AC) power source, the power supply system comprising:

a flywheel system comprising a flywheel and an AC motor/generator electrically coupled to a direct current (DC) bus, the flywheel system configured to store, as kinetic energy, power received from the power source and, when power to the load from the power source decreases below a specified threshold, to provide the stored power to the load as electrical power through the DC bus;

a battery system electrically coupled concurrently with the flywheel system and without a switching circuit to the DC bus, the battery system to receive power from the power source and the battery system configured to remain electrically coupled to the DC bus while the flywheel system is providing power to the load, to store power received from the power source and to provide power to the load through the DC bus; and

a controller coupled to the flywheel system and the battery system, the controller configured to monitor the flywheel system and the battery system.

2. The power supply system of claim 1 , where the controller is configured to provide status indications for the flywheel system and the battery system.

3. The power supply system of claim 1 , where in monitoring the battery system, the controller is configured to monitor at least one of battery voltage, temperature, current, and for presence of an open circuit.

4. The power supply system of claim 1 , where in monitoring the flywheel system, the controller is configured to monitor at least one of rotational speed and voltage output.

5. The power supply system of claim 1 , where the flywheel system is configured to initially output electrical power at a voltage that is greater than the battery system is configured to initially output, and where the voltage output from the flywheel system decreases as the flywheel system provides power to the load.

6. The power supply system of claim 5 , where the battery system is configured to provide power to the load when the voltage of the power output by the flywheel system decreases to below the initial voltage of the power output by the battery system.

7. The power supply system of claim 1 , where the motor/generator comprises a rotor having permanent magnets.

8. The power supply system of claim 1 , where the flywheel is coupled to rotate at the same speed as a rotor of the motor/generator.

9. The power supply system of claim 1 , where the power source is a utility power grid.

10. The power supply system of claim 1 , where the battery system and the flywheel system reside in a common housing.

11. A method, comprising:

supplying AC power from a flywheel system, rectified, to a DC bus while a battery system is electrically coupled without a switching circuit to the DC bus concurrently with the flywheel system, the battery system and the flywheel system to receive power from a power source, the DC bus coupled to a load for supplying power to the load through the DC bus;

supplying DC power from the battery system to the DC bus; and

monitoring the flywheel system and the battery system with a common controller.

12. The method of claim 11 , further comprising supplying AC power from the power source to the flywheel system to charge the flywheel system.

13. The method of claim 11 , further comprising inverting the power from the DC bus into AC and supplying the AC power to the load.

14. The method of claim 11 , where monitoring the battery system comprises monitoring at least one of battery voltage, temperature, current, and open circuit.

15. The method of claim 11 , where monitoring the flywheel comprises monitoring at least one of rotational speed and voltage output.

16. The method of claim 11 where supplying power from a flywheel system to a DC bus comprises supplying power at a higher voltage than a voltage of the battery system, the higher voltage from the flywheel system decreasing to a voltage below the voltage of the battery system, and wherein the method further comprises supplying power at the voltage of the battery system in response to the higher voltage from the flywheel system decreasing to or below the voltage of the battery system.

17. A power supply system for providing backup power to a load powered by an AC power source, comprising:

a flywheel system comprising a flywheel and a motor/generator electrically coupled to a DC bus to provide power to the DC bus, the flywheel configured to receive power from the AC power source, the DC bus for supplying electrical power to the load;

a battery system electrically coupled without a switching circuit to the DC bus to supply power to the DC bus, the battery system configured to remain electrically coupled to the DC bus concurrently with the flywheel system while the flywheel system is providing power to the DC bus, and to supply power to the load through the DC bus in response to a voltage of the power supplied to the load by the flywheel system falling below a voltage at which the battery system is configured to supply power to the load; and

a controller coupled to the flywheel system and the battery system, the controller configured to monitor the flywheel system and the battery system.

18. The power supply system of claim 17 , where in monitoring the battery system, the controller is configured to monitor at least one of battery voltage, temperature, current, and open circuit.

19. The power supply system of claim 17 , where in monitoring the flywheel system, the controller is configured to monitor at least one of rotational speed and voltage output.

20. The power supply system of claim 17 further comprising a housing enclosing the flywheel system and the battery system.

21. The power supply system of claim 17 , where the flywheel system is configured to supply power to the DC bus at a higher voltage than a voltage of power supplied by the battery system to the DC bus.