Method and apparatus for a power system for phased-array radar

• US 20040257271A1
• Filed: 02/28/2003
• Published: 12/23/2004
• Est. Priority Date: 02/28/2003
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: McGinty, John, Thomas, Paul Christian, Jacobson, Boris Solomon
• Granted Patent: US 6,856,283 B2
• Time in Patent Office: Days
• US Class Current: 342/175
• CPC Class Codes: G01S 2013/0254 Active array antenna
• CPC Class Codes: G01S 7/282 Transmitters
• CPC Class Codes: G01S 7/4008 of transmitters

Abstract

A power system for a phased-array radar system powers an antenna array with a single multiphase transformer. A plurality of AC/DC converters are connected in parallel between the single multiphase transformer and a common bus. The common bus is balanced with respect to chassis ground reducing noise and improving operating safety of the antenna. The AC/DC converters each has a multi-sloped characteristic which enables the converters to share power by modifying output impedance as a function of load without external control signals. The system also has several layers of fault detection.

Claims

1. A power system for a radar antenna, comprising:

a multiphase transformer;

a common bus; and

a plurality of power converters coupled in parallel to said multiphase transformer and said common bus, each said power converter having a multisloped power output characteristic to enable power sharing by said plurality of power converters.

2. The power system of claim 1, wherein each of said power converters comprises:

an output voltage loop controller;

an output power loop controller;

an output current loop controller,

where said output voltage loop controller, said output power loop controller and said output current loop controller together provide said multi-sloped power output characteristic, each of said power converters providing;

a constant voltage when in a voltage mode controlled by said output voltage loop controller,

a constant power output when in a constant power mode controlled by said output power loop controller, and

a constant current when in a current mode controlled by said output current loop controller.

3. The power system of claim 2, wherein one of said plurality of power converters operates to provide power to the radar antenna when in said constant voltage mode and wherein at least one of said plurality of power converters operate to provide constant power to the radar antenna when in said constant power mode.

4. The power system of claim 1, wherein said common bus is a substantially balanced bus with respect to ground.

5. The power system of claim 4, wherein said common bus is substantially balanced at +150 V and −

150 V.

6. The power system of claim 1, wherein each of said power converters includes a ground fault detection circuit having a sensing resistor to detect current resulting from a ground fault.

7. The power system of claim 6 wherein said ground fault detection circuit further includes time delay devices to provide a time delay in a current detection signal to a power system controller generated in response to a current at said sensing resistor, the time delay to distinguish a current detection signal from a power converter having a ground fault from a power converter without a ground fault.

8. The power system of claim 7, wherein said time delay devices delay a current detection signal from said power converter without a ground fault so that a current detection signal from said power converter having a ground fault has a faster rate of rise.

9. The power system of claim 7, wherein said time delay devices comprise a balun and a sensing resistor.

10. The power system of claim 6, wherein a fast-rising signal from said sensing resistor indicates that a corresponding power converter has failed thereby signaling to the power system to take said corresponding power converter off-line.

11. The power system of claim 6, wherein each said ground fault detection system of each power converter generates a current in response to an external ground fault, said currents to combine into a combined ground fault detection current, said power system further comprising a fuse characterized and located to fail when said fuse receives said combined ground fault detection current.

12. The power system of claim 1 further comprising:

a first Hall effect sensor at an input of said common bus to sense input current to said common bus and a second Hall effect sensor at an output of said common bus to detect output current from said common bus; and

a common bus fault detector in a power system controller in said power system to monitor said first Hall effect sensor and said second Hall effect sensor to determine a difference between said input current and said output current to detect a fault in said common bus.

22. The power system as in claim 1, wherein the multiphase transformer includes multiple output signals that feed the power converters;

and

wherein the power converters convert power from the multiple output signals and share a burden of providing power to the common bus.

23. The power system as in claim 22, wherein each of the power converters supplies substantially the same amount of power to the common bus.

24. The power system as in claim 23, wherein each of the power converters produces a DC (Direct Current) output that feeds the common bus.

25. The power system as in claim 24, wherein each of the power converters includes i) fault detection circuitry to detect an occurrence of a failure associated with a respective power converter, and ii) isolation circuitry to isolate the respective power converter from the common bus during the occurrence of a failure.

27. The power system as in claim 1, wherein the radar antenna is a phased array antenna.

13. A power supply for a power system for a radar antenna, comprising:

an output voltage loop controller;

an output power loop controller;

an output current loop controller,

where said output voltage loop controller, said output power loop controller and said output current loop controller together provide a multi-sloped power output characteristic, said power supply to provide;

a constant voltage in a constant voltage mode controlled by said output voltage loop controller,

an increasing current while voltage decreases in a constant power mode controlled by said output power loop controller, and

a constant current in a constant current mode controlled by said output current loop controller.

14. The power supply of claim 13, wherein each of said power converters includes a ground fault detection circuit having a sensing resistor to detect current resulting from a ground fault.

15. The power supply of claim 14, wherein the ground fault detection circuit further includes time delay devices to provide a time delay in a current detection signal to a power system controller generated in response to a current at said sensing resistor, the time delay to distinguish a current detection signal from a power converter having a ground fault from a power converter without a ground fault.

16. The power supply of claim 15, wherein the time delay devices delay a current detection signal from a corresponding power converter without a ground fault so that a current detection signal from said corresponding power controller having a ground fault has a faster rate of rise.

17. The power supply of claim 14, wherein a fast-rising signal from said sensing resistor indicates that said converter has failed thereby signaling to the power system to take said corresponding power converter off-line.

28. The power system as in claim 13, wherein the radar antenna is a phased array antenna.

18. A method of supplying power from a plurality of power converters to a radar antenna, each converter of the plurality having a voltage loop controller, a power loop controller, and a current loop controller, the method comprising the steps of:

providing power from one power converter of said plurality by controlling said plurality of power converters by the voltage loop controllers until power required by the radar antenna causes an output feedback voltage of said one power converter to exceed a voltage limit;

providing power from at least two power converters of said plurality of power converters by controlling said plurality of converters with the power loop controllers until power required by the radar antenna exceeds a power limit for said at least two power converters; and

providing a constant current from the plurality of power converters by controlling said plurality of power converters by the current loop controllers.

19. The method of claim 18 wherein the step of providing power from at least two power converters in constant power mode further comprises the steps of initially providing power from a first converter having a highest output voltage converter, and then as a voltage output level of the first converter decreases in constant power mode, providing power from another power converter of said plurality of power converters having a second highest output voltage.

29. The method as in claim 18, wherein the radar antenna is a phased array antenna.

20. (Canceled)

21. A power system for a load coupled to a common bus, comprising:

a plurality of power converters coupled in parallel to the common bus, each power converter including

(a) an output voltage loop controller;

(b) an output power loop controller; and

(c) an output current loop controller,

where said output voltage loop controller, said output power loop controller and said output current loop controller together provide said multi-sloped power output characteristic, each said power converter to provide

a constant voltage in a voltage mode controlled by said output voltage loop controller,

an increasing current while voltage is decreasing in a constant power mode controlled by said output power loop controller, and

a constant current in a current mode controlled by said output current loop controller,

whereby said plurality of power converters cooperate to balance the power provided to the load among said plurality of power converters.

26. The power system as in claim 21, wherein each of the power converters generates a respective power converter output signal coupled to provide power to the common bus, the power converters sharing a burden of providing power to the common bus.

30. The power system as in claim 21, wherein the load is a phased array antenna.

31. A power supply providing power to a variable load, the power supply comprising:

an output voltage loop controller;

an output power loop controller; and

an output current loop controller,

wherein a combination of i) the output voltage loop controller, ii) the output power loop controller, and iii) the output current loop controller supports multiple power conversion modes depending on characteristics of the variable load, the power supply providing;

a constant voltage output when in a constant voltage mode controlled by said output voltage loop controller,

a constant power output when in a constant power mode controlled by said output power loop controller, and

a constant current output when in a constant current mode controlled by said output current loop controller.

32. A method of supplying power from a power converter to a variable load, the method comprising:

measuring a power converter output voltage and power converter output current of the power converter;

controlling the power converter using a voltage loop controller to provide a substantially constant voltage i) while the power converter output voltage is greater than a first voltage threshold and less than a power converter output voltage without a load on the power converter, and ii) while output current is greater than zero and less than a first current threshold, during which the power converter powers a relatively light load;

controlling the power converter using a power loop controller to provide substantially constant power i) while the output voltage is greater than a second voltage threshold and less than the first voltage threshold and ii) while output current is greater than the first current threshold and less than a second current threshold, during which the power converter powers a relatively heavy load;

controlling the converter using a current loop controller to provide substantially constant current i) while the output voltage is greater than a third voltage threshold and less than the second voltage threshold and ii) while output current is greater than the second current threshold and less than a third current threshold, during which the converter operates at substantially constant current when the load on the power converter attempts to exceed a power limit associated with the power converter; and

controlling the converter using a foldback circuit while the output voltage is greater than zero and less than the third threshold voltage, during which the power converter recovers from an overload condition.

33. A power system for providing power to a variable load, the power system comprising:

a plurality of power converters to convert received power signals into corresponding power converter output signals that feed a common bus, the plurality of power converters sharing a burden of feeding power to the common bus; and

each of the power converters including an independent control circuit to support generating a respective power converter output signal feeding the common bus, the independent control circuit of a respective power converter supporting multiple power converter output modes which are activated depending on characteristics of the load.

34. A power system as in claim 33, wherein the independent control circuit of a respective power converter includes:

an output voltage loop controller;

an output power loop controller;

an output current loop controller,

wherein a combination of i) the output voltage loop controller, ii) the output power loop controller, and iii) the output current loop controller supports the multiple power converter output modes depending on characteristics of the variable load, the respective power converter providing;

a constant voltage output when in a constant voltage mode controlled by said output voltage loop controller,

a constant power output when in a constant power mode controlled by said output power loop controller, and

a constant current output when in a constant current mode controlled by said output current loop controller.