AIRCRAFT SOLID STATE POWER CONTROLLER AND METHOD OF TESTING AN AIRCRAFT SOLID STATE POWER CONTROLLER

Abstract

An aircraft solid state power controller for controlling the supply of electric power from an aircraft electric power supply to an electric load comprises a power input node, which is electrically connectable to an output node of the aircraft electric power supply; a power output node, which is electrically connectable to an electric load and configured for selectively supplying electric power to the electric load; an electric load switch, which is configured for controlling the supply of electric power from the power input node to the power output node; a shunt resistor, which is arranged between the electric load switch and the power output node so that any electric current that is supplied from the aircraft solid state power controller via the power output node to the electric load passes through the shunt resistor; and a control device comprising a voltage sensor that is configured for detecting a voltage drop over the shunt resistor.

Claims

1. Aircraft solid state power controller for controlling the supply of electric power from an aircraft electric power supply to an electric load, the aircraft solid state power controller providing a circuit breaker function and comprising: a power input node, which is electrically connectable to an output node of the aircraft electric power supply; a power output node, which is electrically connectable to an electric load and configured for selectively supplying electric power to the electric load; an electric load switch, which is configured for controlling the supply of electric power from the power input node to the power output node; a shunt resistor, which is arranged between the electric load switch and the power output node so that any electric current that is supplied from the aircraft solid state power controller via the power output node to the electric load passes through the shunt resistor; and a control device comprising a voltage sensor that is configured for detecting a voltage drop over the shunt resistor; the aircraft solid state power controller further comprising a stim circuit that is configured for causing an electric stim current to flow through the shunt resistor, the stim circuit comprising: a stim capacitor that is selectively connectable to the shunt resistor for applying an electric voltage to the shunt resistor causing the stim current to flow through the shunt resistor by discharging the stim capacitor; and a stim switch that is configured for selectively connecting the stim capacitor to the shunt resistor.

2. Aircraft solid state power controller according to claim 1, wherein at least one of the electric load switch and of the stim switch is a solid state switch.

3. Aircraft solid state power controller according to claim 2, wherein the solid state switch is one of a field-effect transistor or a metal-oxide-semiconductor field-effect transistor.

4. Aircraft solid state power controller according to claim 1, further comprising a low-pass filter, which is arranged between the shunt resistor and the voltage sensor.

5. Aircraft solid state power controller according to claim 4, wherein the low-pass filter has a cutoff-frequency in the range of 1 kHz to 1 MHz.

6. Aircraft solid state power controller according to claim 5, wherein the low-pass filter has a cutoff-frequency in the range of 10 kHz to 500 kHz.

7. Aircraft solid state power controller according to claim 1, wherein the stim capacitor has a capacity in the range 10 ?F to 470 ?F.

8. Aircraft solid state power controller according to claim 7, wherein the stim capacitor has a capacity in the range 100 ?F to 270 ?F.

9. Aircraft solid state power controller according to claim 1, wherein the stim capacitor is configured for being loaded with a voltage in the range of 7 V to 20 V before being connected to the shunt resistor.

10. Aircraft solid state power controller according to claim 1, further comprising an isolated electric power supply for providing an electric output to the control device and to the stim circuit, wherein the electric output provided by the isolated electric power supply is galvanically isolated from the aircraft electric power supply, wherein the isolated electric power supply is configured for providing an electric DC power output.

11. Aircraft solid state power controller according to claim 10, wherein the isolated electric power supply is configured for supplying electric power having a voltage in the range of 7 V to 20 V.

12. Aircraft solid state power controller according to claim 1, wherein the electric load switch is configured for switching electric loads of up to 1000 kW, voltages up to 3000 V and/or electric currents of up to 1000 A.

13. Aircraft solid state power controller according to claim 1, wherein the shunt resistor has a resistivity in the range of 10 ??to 10 m?.

14. Aircraft solid state power controller according to claim 13, wherein the shunt resistor has a resistivity in the range of 50 ?? to 1 m?.

15. Aircraft solid state power controller according to claim 1, wherein the control device is configured for switching off the electric load switch for interrupting the supply of electric power to the electric load when the detected voltage drop at the shunt resistor exceeds a predefined threshold.

16. Aircraft comprising: an aircraft electric power supply; at least one electric load; and an aircraft solid state power controller according to claim 1, which is configured for controlling the supply of electric power from the aircraft electric power supply to the at least one electric load; wherein the aircraft electric power supply is configured for providing an electric DC power output.

17. Aircraft according to claim 16, wherein the electric DC power output is a voltage in the range of 1500 V to 3000 V.

18. Method of testing an aircraft solid state power controller according to claim 1, wherein the method includes: charging the stim capacitor by applying an electric voltage to the stim capacitor; switching on the stim switch for electrically connecting the stim capacitor with the shunt resistor and causing an electric stim current to flow through the shunt resistor; and measuring the voltage drop over the shunt resistor.

19. Method according to claim 18, wherein the method further includes comparing the measured voltage drop with a predefined voltage drop threshold and indicating a malfunction of the aircraft solid state power controller if the measured voltage drop does not exceed the predefined voltage drop threshold.

20. Method according to claim 18, wherein the method further includes switching off the electric load switch before switching on the stim switch.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, other embodiments thereof will be described in detail herein below with reference to certain figures, wherein:

[0029] FIG. 1 shows an aircraft comprising an aircraft solid state power controller according to an exemplary embodiment of the invention; and

[0030] FIG. 2 shows a circuit diagram of an aircraft solid state power controller according to an exemplary embodiment of the invention.

DETAILED DESCRIPTION

[0031] In the following, an SSPC according to an exemplary embodiment of the invention is described with reference to the enclosed figures.

[0032] FIG. 1 shows an aircraft 1, in particular an airplane, which is equipped with an aircraft electric power supply system 3 including an aircraft electric power supply 4, an electric load 6, and an aircraft solid state power controller (SSPC) 2 according to an exemplary embodiment of the invention, which is configured for controlling the supply of electric power from the aircraft electric power supply 4 to the electric load 6.

[0033] Although the aircraft electric power supply system 3 depicted in FIG. 1 includes only a single aircraft electric power supply 4, a single electric load 6, and a single SSPC 2, respectively, alternative embodiments of aircraft electric power supply system 3 may comprise more the one of each of said components, respectively.

[0034] An aircraft electric power supply system 3 may in particular include a plurality of SSPCs 2, wherein each SSPC 2 includes numerous SSPC channels of the type depicted in FIG. 2 and described in the following.

[0035] FIG. 2 shows a circuit diagram of a SSPC 2 according to an exemplary embodiment of the invention.

[0036] The SSPC 2 is configured for controlling the supply of electric power from the aircraft electric power supply 4 to the electric load 6.

[0037] The SSPC 2 comprises a power input node 8 and a power output node 10. The power input node 8 is electrically connected to a first node 4a of the aircraft electric power supply 4, and the power output node 10 is electrically connected to a first node 6a of the electric load 6. An second node 6b of the load 6 is connected to a second node 4b of the aircraft electric power supply 4.

[0038] The aircraft electric power supply 4 may be a DC power supply, which is configured to supply electric voltages U.sub.0 in the range of between 28 V and 3000 V, in particular electric voltages U.sub.0 in the range of between 1500 V and 3000 V.

[0039] In the embodiment depicted in FIG. 2, the SSPC 2 is connected between the positive (+) pole 4a of the aircraft electric power supply 4 and the positive (+) pole 6a of the electric load 6. In a alternative embodiment, which is not explicitly depicted in the figures, the SSPC 2 may be connected between the negative (?) pole 4b of the aircraft electric power supply 4 and the negative (?) pole 6b of the electric load 6.

[0040] The SSPC 2 comprises an electric load switch 12, which is configured for controlling the supply of electric power from the power input node 8 to the power output node 10 of the SSPC 2. Thus, the supply of electric power from the aircraft electric power supply 4 to the electric load 6 may by controlled, in particular switched on and off, by controlling, in particular switching, the electric load switch 12.

[0041] The electric load switch 12 may be a solid state power switch, which is capable to switch large electric powers. The electric load switch 12 may in particular capable to switch electric powers of up to 1000 kW, voltages in the range of 28 V and 3000 V, in particular electric voltages U.sub.0 in the range of between 1500 V and 3000 V, and electric currents of up to 1000 A.

[0042] The electric load switch 12 may be a solid state power switch, in particular a power transistor, for example a power insulated-gate bipolar transistor (IGBT) or a power field-effect transistor (FET), in particular a power metal-oxide-semiconductor field-effect transistor (MOSFET).

[0043] The SSPC 2 further includes a shunt resistor 14, which is electrically connected between the electric load switch 12 and the power output node 10. In consequence, the electric current I.sub.load that is supplied from the SSPC 2 via the electric load switch 12 and the power output node 10 to the electric load 6 passes through the shunt resistor 14. The shunt resistor may have a resistivity R.sub.shunt in the range of 10 ?? to 10 m?, in particular a resistivity R.sub.shunt in the range of 50 ?? to 1 m?.

[0044] The SSPC 2 further comprises a control device 16 for controlling the electric load switch 12 via a gate driver 11. The control device 16 includes a voltage sensor 18. The voltage sensor 18 is electrically connected parallel to the shunt resistor 14 for detecting a voltage drop ?U over the shunt resistor 14. According to Ohm's law, the voltage drop ?U over the shunt resistor 14 is proportional to the electric current I.sub.shunt flowing through the shunt resistor 14: ?U=R.sub.shunt*I.sub.shunt.

[0045] In consequence, when the electric current I.sub.shunt flowing through the electric load 6 exceeds a predefined maximum current I.sub.max, the voltage drop ?U over the shunt resistor 14 exceeds a predefined threshold U.sub.th=R.sub.shunt*I.sub.max.

[0046] For providing the circuit breaker functionality of the SSPC 2, the control device 16 may be configured to switch off the supply of electric power to the electric load 6 by switching off the electric load switch 12, when the voltage drop ?U over the shunt resistor 14, which is detected by the voltage sensor 18, exceeds the predefined threshold U.sub.th.

[0047] The SSPC 2 also comprises an isolated electric power supply 30 for providing an electric power output to the control device 16. The electric power output provided by the isolated electric power supply 30 supply may be galvanically isolated from the electric output provided by the aircraft power supply 4. The isolated electric power supply 30 may in particular be configured for providing an electric DC power output, more particularly an electric DC power output having a voltage U.sub.1 in the range of 7 V to 20 V.

[0048] The SSPC 2 further comprises a stim circuit 20 that allows causing an electric stim current I.sub.stim to flow through the shunt resistor 14.

[0049] The stim circuit 20 comprises a stim capacitor 22, a stim switch 24, and a stim resistor 25. The stim capacitor 22 is electrically connected to an output node of the isolated electric power supply 30 via the stim resistor 25, so that the stim capacitor 22 may be charged by the isolated electric power supply 30 via the stim resistor 25.

[0050] In an alternative embodiment, which is not explicitly depicted in the figures, the stim capacitor 22 may be charged by the aircraft power supply 4 instead of the isolated electric power supply 30. This may in particular apply to aircraft electric power supply system 3 that are operated at low voltages, in particular at voltages below 100 V, for example at a voltage of 28 V.

[0051] The stim switch 24 is configured for selectively connecting the stim capacitor 22 to the shunt resistor 14. When the stim switch 24 is switched on, so that it electrically connects the stim capacitor 22 to the shunt resistor 14, the stim capacitor 22 is discharged through the shunt resistor 14. Discharging the stim capacitor 22 through the shunt resistor 14 causes a stim current I.sub.stim to flow through the shunt resistor 14. The stim current I.sub.stim flowing through the shunt resistor 14 results in a voltage drop ?U=?U.sub.stim over the shunt resistor 14. This voltage drop ?U may be detected by the voltage sensor 18 of the control device 16.

[0052] The stim switch 24 may be a solid state switch, in particular a transistor, for example an insulated-gate bipolar transistor (IGBT) or a power field-effect transistor (FET), in particular a power metal-oxide-semiconductor field-effect transistor (MOSFET).

[0053] The stim switch 24 may be configured for switching voltages in the range of 7 V and 20 V, and electric currents of up to 20 A. Contrary to the electric load switch 12, the stim switch 24 needs to withstand the electric power of the stim current I.sub.stim only for a short period time, as the stim current I.sub.stim is not constantly flowing through the shunt resistor 14, but only a short current pulse or spike having a length of not more than 1 ms is caused to flow through the shunt resistor 14.

[0054] The capacity of the stim capacitor 22 is selected so that the stim current I.sub.stim, which flows through the shunt resistor 14 when the stim switch 24 is switched on, is similar to, i.e. it is in the same order of magnitude, as the load current I.sub.load, which flows through the load 6 during normal operation, when the electric load switch 12 is switched on.

[0055] In consequence, the voltage drop ?U.sub.stim over the shunt resistor 14, which is detected by the voltage sensor 18 of the control device 16, is similar to the voltage drop ?U over the shunt resistor 14 that is caused by the electric current I.sub.load flowing through the load 6 during normal operation. The stim capacitor 22 may have a capacity C.sub.stim in the range 10 ?F to 470 ?F, in particular a capacity C.sub.stim in the range 100 ?F to 270 ?F.

[0056] The stim capacitor 22 may in particular be selected so that the stim current I.sub.stim flowing through the shunt resistor 14 exceeds the predefined maximum current I.sub.max, and, in consequence, the voltage drop ?U.sub.stim over the shunt resistor 14 exceeds the predefined threshold U.sub.th. In consequence, an overcurrent situation should be identified by the control device 16.

[0057] Thus, detecting an overcurrent by the control device 16 confirms that the circuit breaker functionality of the SSPC is correctly working. Correspondingly, a malfunction of the SSPC is identified in case no overcurrent is detected when the stim capacitor 22 is discharged.

[0058] Thus, a stim circuit 20 according to an exemplary embodiment of the invention allows for testing the circuit breaker functionality of the SSPC 2 by causing a sufficiently large stim current I.sub.stim to flow through the shunt resistor 14.

[0059] The stim current I.sub.stim may be in the range of 1 A to 20 A, and the predefined threshold U.sub.th of the voltage drop ?U at the shunt resistor 14 may be in the range of 100 mV to 1 V, in particular in the range of 200 mV to 750 mV.

[0060] The electric load switch 12 may be switched off before the stim switch 24 is switched on in order to prevent an additional voltage drop ?U.sub.load caused by a load current I.sub.load flowing through the electric load 6, which could falsify the test result.

[0061] Since the generated stim current I.sub.stim is a short current pulse or spike, high frequency components (high harmonics) may be generated together with the stim current I.sub.stim. In order to avoid electromagnetic distortions, which may be caused by these high frequency components, a low-pass filter 26, 28 comprising a low-pass filter capacitor 26 and a low-pass filter resistor 28 is provided in the electric connection between the shunt resistor 14 and the voltage sensor 18.

[0062] The low-pass filter 26, 28 may have a cutoff-frequency f.sub.C in the range of 1 kHz to 1 MHz, in particular a cutoff-frequency f.sub.C in the range of 5 kHz to 500 kHz, more particularly a cut-off-frequency f.sub.C between 10 kHz and 500 kHz.

[0063] While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.