Apparatus and system for power conversion

1. An apparatus comprising:

a DC-link;

a load coupled to the DC-link; and

an energy conversion system comprising:

a first energy storage device;

a first voltage converter coupled to the first energy storage device and to the DC-link, the first voltage converter configured to:

convert a first DC voltage from the first energy storage device into a second DC voltage based on a command signal and based on a first adjustment signal; and

supply the second DC voltage to the DC-link;

a first bus voltage controller coupled to the DC-link and to the first voltage converter, the first bus voltage controller configured to:

iterate calculation of the first adjustment signal based on the command signal and based on a measured voltage of the DC-link; and

communicate each iterated calculation of the first adjustment signal to the first voltage converter;

a supervisory controller coupled to the first voltage converter and to the first bus voltage controller, the supervisory controller configured to:

iterate calculation of the command signal based on the load and based on a desired DC-link voltage for the load; and

communicate each iterated calculation of the command signal to the first voltage converter and to the first bus voltage controller; and

wherein a frequency of the first bus voltage controller to communicate each iterated calculation of the first adjustment signal is higher than a frequency of the supervisory controller to communicate each iterated calculation of the command signal.

2. The apparatus of claim 1 further comprising a voltage measurement device coupled to the DC-link and configured to:

measure a voltage of the DC-link; and

communicate the measured voltage to the first bus voltage controller.

3. The apparatus of claim 1 further comprising:

a second energy storage device;

a second voltage converter coupled to the second energy storage device and to the DC-link, the second voltage converter configured to:

convert a third DC voltage from the second energy storage device into a fourth DC voltage based on the command signal; and

supply the fourth DC voltage to the DC-link.

4. The apparatus of claim 3 wherein the second voltage converter is further configured to convert the third DC voltage into the fourth DC voltage based on the command signal and based on a regulation setpoint signal transmitted from the first voltage converter.

5. The apparatus of claim 4 wherein the first voltage converter is configured to:

determine a total desired output voltage of the first voltage converter from the command signal and from the first adjustment signal;

determine a difference between the second DC voltage supplied to the DC-link and the total desired output voltage;

calculate the regulation setpoint signal based on the difference, the regulation setpoint signal configured to cause the second voltage converter to increase the fourth DC voltage by the difference; and

transmit the regulation setpoint signal to the second voltage converter.

6. The apparatus of claim 3 wherein the energy conversion system further comprises:

a second bus voltage controller coupled to the DC-link and to the second voltage converter, the second bus voltage controller configured to:

iterate calculation of a second adjustment signal based on the command signal and based on the measured voltage of the DC-link; and

communicate each iterated calculation of the second adjustment signal to the second voltage converter;

wherein the second voltage converter is further configured to convert the third DC voltage into the fourth DC voltage based on the command signal and based on the second adjustment signal.

7. The apparatus of claim 6 wherein the first energy storage device comprises one of a battery and an ultracapacitor.

8. The apparatus of claim 1 further comprising a second energy storage device coupled to the DC-link and configured to filter voltage ripple on the DC-link and to buffer energy.

9. The apparatus of claim 8 wherein the second energy storage device comprises one of a battery and an ultracapacitor.

10. The apparatus of claim 1 wherein the load comprises:

a voltage inverter coupled to the DC-link and configured to convert a DC voltage from the DC-link into a first AC voltage; and

an electromechanical device coupled to the voltage inverter and configured to convert the first AC voltage into a mechanical output.

11. An apparatus comprising:

a voltage bus;

a load coupled to the voltage bus;

a voltage converter coupled to the voltage bus and to an energy storage device; the voltage converter configured to convert energy from the energy storage device into a voltage bus voltage;

a supervisory controller coupled to the voltage bus and to the voltage converter, the supervisory controller programmed to iteratively:

determine a desired voltage bus voltage based on the load; and

calculate a control signal based on the desired voltage bus voltage, the control signal configured to cause the voltage converter to convert the energy from the energy storage device into the voltage bus voltage;

a voltage bus controller coupled to the voltage bus, to the voltage converter, and to the supervisory controller, the voltage bus controller programmed to:

receive the voltage feedback from the voltage bus;

receive the control signal from the supervisory controller;

calculate the desired voltage bus voltage based on the control signal;

determine if the voltage feedback is within the threshold of the desired voltage bus voltage; and

if the voltage feedback is outside of the threshold of the desired voltage bus voltage, calculate a regulatory setpoint signal based on the voltage feedback and based on the desired voltage bus voltage, the regulatory setpoint signal configured to cause the voltage converter to adjust the conversion of the energy from the energy storage device such that the voltage on the voltage bus voltage is within the threshold; and

wherein a bandwidth of the voltage bus controller to receive the voltage feedback and calculate the regulatory setpoint signal is higher than a bandwidth of the supervisory controller to iteratively receive the voltage feedback and calculate the control signal.

12. The apparatus of claim 11 further comprising a first voltage measurement device coupled to the voltage bus and configured to:

measure the voltage on the voltage bus; and

provide the measured voltage as the voltage feedback to the voltage bus controller.

13. The apparatus of claim 12 wherein the first voltage measurement device, in being configured to measure the voltage on the voltage bus, is configured to measure an average voltage on the voltage bus.

14. The apparatus of claim 12 further comprising:

a second voltage measurement device coupled to the energy storage device and configured to:

measure a state-of-charge of the energy storage device; and

provide the measured state-of-charge to the supervisory controller; and

wherein the supervisory controller is further programmed to calculate the control signal to optimize an operational life of the energy storage device.

15. The apparatus of claim 11 wherein the load comprises:

a voltage inverter coupled to the voltage bus and configured to convert a DC voltage from the voltage bus into an AC voltage; and

a motor coupled to the voltage inverter and configured to convert the AC voltage into a mechanical output.

16. A system comprising:

a DC-link;

a voltage inverter coupled to the DC-link and configured to convert a DC voltage from the DC-link into a first AC voltage;

an electromechanical device coupled to the voltage inverter and configured to convert the first AC voltage into a mechanical output; and

an energy conversion system comprising:

a plurality of energy storage devices configured to store DC energy;

a plurality of voltage converters, each voltage converter coupled to a respective energy storage device and configured to:

convert a stored voltage from the respective energy storage device into a DC supply voltage based on a setpoint signal; and

supply the DC supply voltage to the DC-link;

a power management controller coupled to the plurality of voltage converters and configured to iteratively:

calculate the setpoint signal based on a target voltage for the DC-link; and

supply the setpoint signal to the plurality of voltage converters;

a first DC-link voltage controller coupled to a first voltage converter of the plurality of voltage converters and to the power management controller, wherein the first DC-link voltage controller is configured to iteratively:

determine the target voltage based on the setpoint signal;

calculate a first adjustment signal based on a difference between the target voltage and the DC supply voltage; and

supply the first adjustment signal to the first voltage converter, wherein the first voltage converter is further configured to convert the stored voltage based on the first adjustment signal; and

wherein a frequency of the power management controller to iteratively calculate the setpoint signal and supply the setpoint signal to the plurality of voltage converters is lower than a frequency of the first DC-link voltage controller to calculate and supply the first adjustment signal to the first voltage converter.

17. The system of claim 16 wherein the first voltage converter is further coupled to a second voltage converter of the plurality of voltage converters, wherein the first voltage converter is configured to iteratively:

calculate a second adjustment signal based on the target voltage and the DC supply voltage of the first voltage converter; and

supply the second adjustment signal to the second voltage converter, wherein the second voltage converter is further configured to convert the stored voltage based on the second adjustment signal.

18. The system of claim 17 wherein the first voltage converter is further configured to:

calculate the second adjustment signal based on a first voltage adjustment range;

calculate a third adjustment signal based on a second voltage adjustment range, wherein the second adjustment range is smaller than the first adjustment range; and

supply the third adjustment signal to a third voltage converter of the plurality of voltage converters.

19. The system of claim 16 further comprising:

a second DC-link voltage controller coupled to a second voltage converter of the plurality of voltage converters and to the power management controller, wherein the second DC-link voltage controller is configured to iteratively:

determine the target voltage based on the setpoint signal;

calculate a second adjustment signal based on a difference between the target voltage and the DC supply voltage; and

supply the second adjustment signal to the second voltage converter, wherein the second voltage converter is further configured to convert the stored voltage based on the second adjustment signal; and

wherein a frequency of the power management controller to iteratively calculate the setpoint signal and supply the setpoint signal to the plurality of voltage converters is lower than a frequency of the second DC-link voltage controller to calculate and supply the second adjustment signal to the second voltage converter.

20. The system of claim 16 further comprising a wheel coupled to the electromechanical device, wherein the apparatus comprises an electric vehicle.