System and Method for Electrical Power Conversion

• US 20100201197A1
• Filed: 05/05/2005
• Published: 08/12/2010
• Est. Priority Date: 05/05/2005
• Status: Active Grant

• Current Assignee: Unitron NV
• Original Assignee: Unitron NV
• Inventors: Shires, Jerry O., Beutel, Raymond L.
• Granted Patent: US 8,610,308 B2
• Time in Patent Office: Days
• US Class Current: 307/73
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02J 2300/30 The power source being a fuel cell
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/10 Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from ac or dc
• CPC Class Codes: H02M 3/285 Single converters with a plurality of output stages connected in parallel parallel operation of a plurality of converters in dc distribution networks H02J1/10

Abstract

A system for combining electrical power from two or more power sources includes first and second conversion stages (120) which receive input power from two or more power sources (110), and produce different output voltages, including DC outputs. The input power sources (110) may have different voltage, frequency, and phase characteristics, and may be DC voltages. Various embodiments are disclosed for converting and combining the input power sources (110) to provide at least a DC output voltage and an optional AC output voltage which may have different voltage, frequency, and phase characteristics than the input power sources (110). In another embodiment, a method of power conversion is disclosed.

Claims

1. A system for combining electrical power from two or more independent power sources, the system comprising:

a first stage which receives a first input voltage from one of the two or more power sources and provides a first DC voltage as an output thereof, wherein the first input voltage has first voltage, first frequency, and first phase characteristics;

a second stage which receives a second input voltage from a different one of the two or more power sources and provides a second DC voltage as an output thereof, wherein the second input voltage has second voltage, second frequency, and second phase characteristics,

wherein the first and second voltage, frequency, and phase characteristics may be different from each other, and may include a DC voltage,

wherein the first and second voltages are also independent from each other;

first and second conversion stages having inputs coupled, respectively, to associated outputs of the first and second stages so as to produce respective first and second isolated voltages as outputs thereof; and

means for combining at least the first and second isolated voltages and providing at least one DC output to one or more associated output terminals.

2. The system of claim 1, wherein the means for combining further provides two AC output voltages having different phase characteristics from each other.

3. The system of claim 1, wherein the first input voltage is a single phase AC voltage, and the second input voltage is a three-phase AC voltage.

4. The system of claim 1, wherein the first input voltage is a DC voltage, and the second input voltage is an AC voltage.

5. The system of claim 1, wherein the first input voltage is an AC voltage.

6. The system of claim 5, wherein the second input voltage is an AC voltage.

7. The system of claim 1, wherein at least one of the first and second input voltages is a DC voltage.

8. The system of claim 1, wherein the first and second conversion stages each comprise a DC-AC inverter.

9. The system of claim 1, wherein, if either one of the first or second input voltages is removed, the at least one DC output is maintained at a same power level.

10. The system of claim 1, wherein the means for combining further provides an AC output voltage at an output frequency different from each of the first and second frequencies.

11. The system of claim 10, further comprising:

a system controller which at least receives, as inputs thereof, user inputs, the first and second input voltages, and the AC output voltage;

wherein, responsive to the user inputs, the system controller provides control signals operative to control the first and second stages and the first and second conversion stages,

wherein, responsive to the control signals, one or more characteristics of the AC output voltage are controlled to user-defined values by the system controller.

12. The system of claim 11, wherein the one or more characteristics of the at least one AC output voltage controlled by the system controller include a voltage magnitude and a phase of the AC output voltage.

13. The system of claim 11, wherein the system controller is effective, based upon a user input, to control a frequency of the AC output voltage to be at a selectable frequency in the range of approximately 50 to 800 Hz.

14. The system of claim 11, wherein the system controller is operable to effectively control the frequency of the AC output voltage when at least the first input voltage is an AC voltage in the range of approximately 50 to 800 Hz.

15. The system of claim 1, further comprising means for receiving and conditioning more than two voltage inputs and providing at least one DC output to one or more associated output terminals by combining the more than two voltage inputs.

16. The system of claim 1, wherein at least one of the first and second input voltages comprises a three-phase AC input voltage.

17. The system of claim 1, wherein the first stage is a DC rectification stage.

18. The system of claim 1, further comprising a gate controller which monitors the first input voltage and produces a gate control signal responsive thereto,

wherein the first stage comprises at least a pair of insulated-gate bipolar transistors (IGBTs),

wherein the first input voltage is coupled to a node between the pair of IGBTs,

wherein the gate control signal is coupled to a gate of one IGBT of the pair of IGBTs.

19. The system of claim 1, further comprising a gate controller which monitors the at least one DC output and produces a pulse-width modulated (PWM) gate control signal responsive thereto,

wherein the means for combining at least the first and second isolated voltages comprises at least a pair of insulated-gate bipolar transistors (IGBTs),

wherein the PWM gate control signal is applied to a gate of one IGBT of the pair of IGBTs.

20. The system of claim 1, wherein the means for combining at least the first and second isolated voltages comprises an isolation transformer arranged between an inverter circuit and an intermediate voltage node.

21. The system of claim 1, wherein the at least one DC output comprises plural output voltages, the system further comprising connection means for adding at least a portion of the plural output voltages together to form at least one augmented output voltage.

22. The system of claim 1, further comprising a system controller which monitors a presence of the first and second input voltages;

and

wherein, when input power available from a combination of the first and second input voltages is reduced below a threshold value, the system controller provides an output signal operable to initiate a generator startup sequence for an electrical generator.

23. The system of claim 1, wherein the first and second conversion stages each comprise:

plural DC-AC inverters which convert, respectively, the first and second DC voltages to associated first and second intermediate AC voltages,

wherein the means for combining at least the first and second isolated voltages comprises an AC-DC rectifier block which receives, through associated first and second isolation transformers, the first and second intermediate AC voltages from the plural DC-AC inverters.

24. A system for electrical power conversion, the system comprising:

a first DC rectification stage which receives a first AC input voltage having first voltage, first frequency, and first phase characteristics and provides a first DC voltage as an output thereof;

a second DC rectification stage receiving a second AC input voltage having second voltage, second frequency, and second phase characteristics and providing a second DC voltage as an output thereof;

first and second voltage inverters receiving the first and second DC voltages, respectively, and providing first and second AC voltages at an intermediate stage to associated isolation transformers;

a final DC rectification stage coupled to outputs of the associated isolation transformers to receive isolated first and second intermediate AC voltages and to provide at least a final DC voltage; and

an output voltage inverter stage which converts the final DC voltage to one or more output AC voltages at an output frequency having one or more phases.

25. The system of claim 24, wherein the output frequency is different than a frequency of at least one of the first and second frequencies.

26. A system for electrical power conversion suitable for connection to a shipboard isolation transformer, the system comprising:

a first DC rectification stage receiving a first AC input voltage having first voltage, frequency, and phase characteristics and providing a first DC voltage as an output thereof;

a second DC rectification stage receiving a second AC input voltage having second voltage, frequency, and phase characteristics and providing a second DC voltage as an output thereof; and

an output voltage inverter stage which converts the first and second DC voltages to one or more output AC voltages at an output frequency with one or more phases.

27. A system for combining electrical power from two or more electrical power sources, the system comprising:

a first DC rectification module which receives a first AC input voltage having first electrical characteristics and provides a first DC voltage as an output thereof;

a second DC rectification module which receives a second AC input voltage having second electrical characteristics and provides a second DC voltage as an output thereof,

wherein the second electrical characteristics are different from the first electrical characteristics;

combining means for combining the first and second DC voltages;

a voltage inverter which receives the first and second DC voltages and provides at least one AC output voltage to an output terminal; and

controller means for controlling an output frequency and voltage for the at least one AC output voltage.

28. A method for converting electrical power from multiple sources, the method comprising:

sensing a frequency and a voltage of a first electrical power connection;

converting the first electrical power connection to a first DC voltage;

sensing a frequency and a voltage of a second electrical power connection;

converting the second electrical power connection to a second DC voltage;

combining the first and second DC voltages; and

providing an output voltage.

29. The method of claim 28, wherein at least one of the first electrical power connections comprises a DC source.

30. A method of power conversion, comprising:

providing two or more input AC voltages having respective voltage, frequency, and phase characteristics;

rectifying each of the two or more input AC voltages into respective two or more DC voltages;

converting each of the two or more DC voltages into two or more intermediate AC voltages;

coupling each of the two or more intermediate AC voltages to an output stage through associated isolation transformers;

rectifying both of the two or more intermediate AC voltages and providing at least one combined DC voltage; and

converting one of the at least one combined DC voltage into one or more output AC voltages at an output frequency having one or more phases.