Converter for transferring power between DC systems

• US 9,543,842 B2
• Filed: 06/25/2012
• Issued: 01/10/2017
• Est. Priority Date: 06/23/2011
• Status: Expired due to Fees

• Current Assignee: The University Court of the University of Aberdeen
• Original Assignee: The University Court of the University of Aberdeen
• Inventors: Jovcic, Dragan
• Primary Examiner(s): STERRETT, JEFFREY L
• Application Number:
  US14/127,718
• Publication Number:
  US 20140198534A1
• Time in Patent Office: 1,660 Days
• Field of Search: 363/15, 363/16, 363/17, 363/123, 363/125, 363/127, 363/131, 363/132, 363/135, 363/136, 363/137
• US Class Current: 1/1
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/33584 Bidirectional converters
• CPC Class Codes: H02M 7/217 using semiconductor devices only
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The present invention relates to a converter for transferring power between a first DC system of DC voltage V₁ and a second DC system of DC voltage V₂, the converter comprising: —a first AC/DC converter for transforming DC voltage V₁ into a first single phase AC voltage V_1ac, of frequency ω, root mean square line-neutral magnitude V_1acm and angle α₁; a second AC/DC converter for transforming DC voltage V₂ into a second single phase AC voltage V_2ac, of frequency ω, root mean square line-neutral magnitude V_2acm and angle α₂; and two inductors L₁, L₂ and a capacitor C, wherein the first terminals of the inductors and capacitor are connected together, the second terminal of inductor L₁ and the second terminal of the capacitor C are connected to the first AC voltage V_1ac, and the second terminal of inductor L₂ and the second terminal of the capacitor C are connected to the second AC voltage V_2ac; wherein the value of the capacitor C, inductor L₁ and inductor L₂ are selected to enable required power transfer and to minimize current in inductor L₁, and/or minimize current in inductor L₂.

Claims

1. A converter for transferring power between a p phase AC system of AC voltage V_1ac of frequency ω

, root mean square line-neutral magnitude V_1acm, and m DC systems respectively of DC voltage V_2i(i=1, 2, . . . m), where m is any positive integer, the converter comprising;

m AC/DC converters for respectively transforming DC voltages V_2i into respective p phase AC voltages V_2iac, of frequency ω

, root mean square line-neutral magnitude V_2iacm and angle α

_2j; and

a LCL circuit for each p phase, wherein each LCL circuit comprises an inductor L₁, m inductors L_2j and a capacitor C connected together at their first terminals, the second terminal of each inductor L₁ being connected to the respective phase of the respective AC voltage V_1ac, and the second terminal of each inductor L_2j being connected to the respective phase of the respective AC voltage V_2jac, wherein the second terminals of all capacitors are connected to a common point;

wherein the value of the capacitor C, inductor L₁ and each inductor L_2j are selected to enable required power transfer and to

minimise current in inductor L₁,

and/or minimise currents in inductors L_2j.

2. A converter according to claim 1 wherein a difference between the AC voltage angles α

₁,α

₂ of substantially

3. A converter according to claim 1 wherein p=1, such that the AC voltages V_1ac and V_2ac are single phase AC-voltages.

4. A converter according to claim 1 comprising control means for controlling power flow though the converter, wherein said control means comprises:

means for varying AC voltage magnitude V_acm by changing the width of the AC pulses;

varying the angle difference between the AC sources (α

₁-α

₂); and

/or

varying the operating frequency ω

of the converter.

5. A converter according to claim 1 wherein p>

1 and the second terminals of the capacitors for all phases are connected to a common point.

6. A converter for transferring power between a p phase AC system of AC voltage V_1ac of frequency ω

, root mean square line-neutral magnitude V_1acm and angle α

₁, and a DC system of DC voltage V₂, the converter comprising;

an AC/DC converter for transforming DC voltage V₂ into a p phase AC voltage V_2ac, of frequency ω

, root mean square line-neutral magnitude V_2acm and angle α

₂; and

a LCL circuit for each p phase, wherein each LCL circuit comprises two inductors L₁,L₂ and a capacitor C connected together at their first terminals, the second terminal of inductor L₁ being connected to the respective phase of AC voltage V_1ac, and the second terminal of inductor L₂ being connected to the respective phase of AC voltage V_2ac, wherein the second terminals of all capacitors are connected to a common point;

wherein the value of the capacitor C, inductor L₁ and inductor L₂ are selected to enable required power transfer and to

minimise current in inductor L₁,

and/or minimise current in inductor L₂.

7. A converter according to claim 6 wherein the value of the capacitor C, inductor L₁ and inductor L₂ are selected to satisfy the following relationships:

k₁=1−

ω

²L₂C k₂=1−

ω

²L₁C

k₃=L₁+L₂−

ω

²L₁L₂C

and where k₁ is selected in the region;

8. A converter according to claim 6 wherein a difference between the AC voltage angles α

₁,α

₂ of substantially

9. A converter according to claim 6 wherein p=1, such that the AC voltages V_1ac and V_2ac are single phase AC-voltages.

10. A converter according to claim 6 comprising control means for controlling power flow though the converter, wherein said control means comprises:

—

means for varying AC voltage magnitude V_acm by changing the width of the AC pulses;

varying the angle difference between the AC sources (α

₁-α

₂); and

/or

varying the operating frequency ω

of the converter.

11. A converter according to claim 6 wherein p>

1 and the second terminals of the capacitors for all phases are connected to a common point.

12. A converter for transferring power between a first DC system of DC voltage V₁ and a second DC system of DC voltage V₂, the converter comprising:

a first AC/DC converter for transforming DC voltage V₁ into a first single phase AC voltage V_1ac, of frequency ω

, root mean square line-neutral magnitude V_1acm and angle α

₁;

a second AC/DC converter for transforming DC voltage V₂ into a second single phase AC voltage V_2ac, of frequency ω

, root mean square line-neutral magnitude V_2acm and angle α

₂; and

two inductors L₁,L₂ and a capacitor C, wherein the first terminals of the inductors and capacitor are connected together, the second terminal of inductor L₁ and the second terminal of the capacitor C are connected to the first AC voltage V_1ac, and the second terminal of inductor L₂ and the second terminal of the capacitor C are connected to the second AC voltage V_2ac;

wherein the value of the capacitor C, inductor L1 and inductor L2 are selected to enable required power transfer and to

minimise current in inductor L1,

and/or minimise current in inductor L2.

13. A converter according to claim 12 wherein the value of the capacitor C, inductor L1 and inductor L2 are selected to satisfy the following relationships:

k₁=1−

ω

²L₂C

k₂=1−

ω

²L₁C

k₃=L₁+L₂−

ω

²L₁L₂C

and where k₁ is selected in the region;

14. A converter according to claim 13 comprising control means for controlling power flow though the converter, wherein said control means comprises:

means for varying AC voltage magnitude by changing the width of the AC pulses;

varying the angle difference between the AC sources (α

₁-α

₂); and

/or

varying the operating frequency ω

of the converter.

15. A converter according to claim 13 wherein a difference between the AC voltage angles α

₁,α

₂ of substantially

16. A converter for transferring power between a first DC system of DC voltage V₁ and a second DC system of DC voltage V₂, the converter comprising:

a first AC/DC converter for transforming DC voltage V₁ into a first p phase AC voltage V_1ac of frequency ω

, root mean square line-neutral magnitude V_1acm and angle α

₁;

a second AC/DC converter for transforming DC voltage V₂ into a second p phase AC voltage V_2ac, of frequency ω

, root mean square line-neutral magnitude V_2acm and angle α

₂; and

a LCL circuit for each p phase, wherein each LCL circuit comprises two inductors L₁,L₂ and a capacitor C connected together at their first terminals, the second terminal of inductor L₁ being connected to the respective phase of the first AC voltage V_1ac, and the second terminal of inductor L₂ being connected to the respective phase of the second AC voltage V_2ac, wherein the second terminals of all capacitors are connected to a common point;

wherein the value of the capacitor C, inductor L1 and inductor L2 are selected to enable required power transfer and to

minimise current in inductor L1,

and/or minimise current in inductor L2.

17. A converter according to claim 16 wherein a difference between the AC voltage angles α

₁,α

₂ of substantially

18. A converter according to claim 16 wherein p=1, such that the AC voltages V_1ac and V_2ac are single phase AC-voltages.

19. A converter according to claim 16 comprising control means for controlling power flow though the converter, wherein said control means comprises:

means for varying AC voltage magnitude V_acm by changing the width of the AC pulses;

varying the angle difference between the AC sources (α

₁-α

₂); and

/or

varying the operating frequency ω

of the converter.

20. A converter according to claim 16 wherein p>

1 and the second terminals of the capacitors for all phases are connected to a common point.

21. A converter according to claim 16 wherein the value of the capacitor C, inductor L1 and inductor L2 are selected to satisfy the following relationships:

k₁=1−

ω

²L₂C k₂=1−

ω

²L₁C

k₃=L₁+L₂−

ω

²L₁L₂C

and where k₁ is selected in the region;

22. A converter for transferring power between n DC systems respectively of DC voltage V_1i(i=1, 2, . . . n) and m DC systems respectively of DC voltage V_2j(j=1, 2, . . . m), where n and m are both any positive integer, the converter comprising:

n AC/DC converters for respectively transforming DC voltages V_1i into respective p phase AC voltages V_1iac of frequency ω

, root mean square line-neutral magnitude V_1iacm and angle α

_1i;

m AC/DC converters for respectively transforming DC voltages V_2j into respective p phase AC voltages V_2jac, of frequency ω

, root mean square line-neutral magnitude V_2jacm and angle α

_2j; and

a LCL circuit for each p phase, wherein each LCL circuit comprises n inductors L_1i, m inductors L_2j and a capacitor C connected together at their first terminals, the second terminal of each inductor L_1i being connected to the respective phase of the respective AC voltage V_1iac, and the second terminal of each inductor L_2j being connected to the respective phase of the respective AC voltage V_2jac, wherein the second terminals of all capacitors are connected to a common point;

wherein the value of the capacitor C, each inductor L_1i and each inductor L_2j are selected to enable required power transfer and to

minimise current in inductors L_1i,

and/or minimise currents in inductors L_2j.

23. A converter according to claim 22 wherein p=1, such that the AC voltages V_1ac and V_2ac are single phase AC-voltages.

24. A converter according to claim 22 comprising control means for controlling power flow though the converter, wherein said control means comprises:

means for varying AC voltage magnitude V_acm by changing the width of the AC pulses;

varying the angle difference between the AC sources (α

₁-α

₂); and

/or

varying the operating frequency ω

of the converter.

25. A converter according to claim 22 wherein p>

1 and the second terminals of the capacitors for all phases are connected to a common point.

26. A converter according to claim 22 wherein a difference between the AC voltage angles α

₁,α

₂ of substantially