Patent Description:
Aircraft often include power supplies for supplying electrical buses with electricity. Electrical buses may be supplied by rotating machines having exciters commonly integrated or within a common shaft to generate magnetic fields. Electrical buses may be designated to provide a particular voltage (e.g., <NUM>). Aircraft electrical buses may operate any number of aircraft loads, including propulsion. Power supplies are disclosed in <CIT>. DC electrical systems that use the rectified output of an AC generator traditionally require two voltage regulation loops; one on the DC side and one on the AC side. Two control loops are needed to deal with a load-off transient that leaves little or no load on the system. There is a need for a simplified control.

A direct current power supply is provided as defined by claim <NUM>.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the multiphase output includes a first multiphase output, a second multiphase output, and a third multiphase output. In addition to one or more of the features described above, or as an alternative, further embodiments may include that the phase voltages comprise a first phase voltages with respect to a neutral reference, a second phase voltages with respect to the neutral reference, and a third phase voltages with respect to the neutral reference, respectively. In addition to one or more of the features described above, or as an alternative, further embodiments may include that the maximum line-to-line voltage is a maximum value of one of: the first phase voltages less the second phase voltages; the second phase voltages less the third phase voltages; or the third phase voltages less the first phase voltages.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the maximum line-to-line voltage is the maximum value less a diode constant.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the generator operates according to a generator cycle that is defined as one full electrical cycle of the generator, and the maximum line-to-line voltage is equal to each of the first phase voltages less the second phase voltages, the second phase voltages less the third phase voltages, and the third phase voltages less the first phase voltages once during the generator cycle.

Also disclosed is a direct current power supply having a controller. The direct current power supply includes digital storage. The direct current power supply includes instructions stored on the digital storage. The instructions are operable upon execution by the controller to receive a phase voltages associated with a multiphase output of a generator, define a maximum line-to-line voltage based on the phase voltages, and operate an exciter winding driver with an oscillating signal generated according to the maximum line-to-line voltage, wherein the phase voltages defines a quadratic mean that is maintained greater than a direct current link capacitor voltage during a load-off.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the multiphase output is a first multiphase output, a second multiphase output, and a third multiphase output. In addition to one or more of the features described above, or as an alternative, further embodiments may include that the phase voltages is a first phase voltages with respect to a neutral reference, a second phase voltages with respect to the neutral reference, and a third phase voltages with respect to the neutral reference, respectively.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the maximum line-to-line voltage is a maximum value of the first phase voltages less the second phase voltages, the second phase voltages less the third phase voltages, or the third phase voltages less the first phase voltages.

In addition to one or more of the features described above, or as an alternative, further embodiments may include a rectifier conductive with the multiphase output having diodes oriented to rectify the multiphase output. In addition to one or more of the features described above, or as an alternative, further embodiments may include a direct current link capacitor configured to provide a direct current link capacitor voltage from the rectifier based on the multiphase output.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the maximum line-to-line voltage is equal to each of the first phase voltages less the second phase voltages, the second phase voltages less the third phase voltages, and the third phase voltages less the first phase voltages once during a generator cycle.

In addition to one or more of the features described above, or as an alternative, further embodiments may include an exciter having an excitation winding and defining an excitation voltage. In addition to one or more of the features described above, or as an alternative, further embodiments may include the generator operable to generate the multiphase output defining the phase voltages based on the excitation voltage.

Also provided is a method for exciting a generator of a direct current power supply with a controller as defined by claim <NUM>.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the phase voltages is a first phase voltages with respect to a neutral reference, a second phase voltages with respect to the neutral reference, and a third phase voltages with respect to the neutral reference, and the maximum line-to-line voltage is a maximum value of the first phase voltages less the second phase voltages, the second phase voltages less the third phase voltages, or the third phase voltages less the first phase voltages.

In addition to one or more of the features described above, or as an alternative, further embodiments may include energizing an excitation winding associated with the exciter winding driver to excite the generator.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the oscillating signal defines a pulse width modulation signal having a duty cycle sized to maintain a direct current link capacitor at a voltage output setpoint.

With reference to the accompanying drawings:.

A detailed description is provided herein. It should be appreciated that any combinations of circuitry, electronics, or communications may be used. Any type of electric machine or generation means may be implemented.

Referring to <FIG>, a schematic diagram of a direct current power supply <NUM> is shown in accordance with one or more implementations of the present disclosure. The direct current power supply <NUM> includes an exciter <NUM>. The exciter <NUM> is driven by one or more excitation windings <NUM>. It should be appreciated that the excitation winding <NUM> may be unitarily disposed with the exciter <NUM> (e.g., stator). That is, excitation winding <NUM> may be the stator, and exciter <NUM> may be the rotor or portions thereof. The excitation windings <NUM> may be self-powered, auxiliary powered, or permanent magnet powered (not shown). The exciter <NUM> is disposed on a common shaft or rotor <NUM> with a generator <NUM>. The exciter <NUM> output is rectified with excitation rectifier <NUM> to generate the rotating electric field on the rotor <NUM>. The rectifier <NUM> may have diodes in a typical half-leg configuration for each of the multiphase outputs 110A, 110B, 110C to rectify the alternating current from the generator <NUM>. The electric field drives multiphase outputs 110A, 110B, 110C from the generator <NUM>. The multiphase outputs 110A, 110B, 110C are rectified with rectifier <NUM>. A direct current link capacitor <NUM> is used to smooth the rectified output from rectifier <NUM> to supply a direct current link capacitor voltage (e.g., the voltage across the capacitor) to the load <NUM>.

Phase voltages 121A, 121B, 121C may be measured from the multiphase outputs 110A, 110B, 110C, using any measurement implementation. It should be appreciated that a three-phase generator <NUM> is shown merely as an example and that any number of phases greater or less than three are contemplated in this disclosure. The phase voltages 121A, 121B, 121C may be determined with respect to ground or neutral <NUM>. Although shown in a Wye configuration, the generator <NUM> may be wound in a Delta configuration. It should be appreciated that the multiphase outputs 110A, 110B, 110C may consist of only one output from the generator <NUM>.

A controller <NUM> may be configured to receive the phase voltages 121A, 121B, 121C. The controller <NUM> may include any combination of processors, field programmable gate arrays (FPGA), or application specific integrated circuits (ASIC), collectively processors <NUM>. The controller <NUM> may include digital storage <NUM>, nonvolatile, operable to store machine instructions from the processors and other processing mechanisms to receive, calculate, and control devices, as necessary. Machine instructions may be stored (e.g., stored instructions, stored machine instructions, stored steps) in any language or representation, including but not limited to machine code, assembly instructions, C, C++, C#, PYTHON. Communications may be realized through any protocol or medium. It should be appreciated that instructions may include any combination of circuitry, logic, memory, and/or machine code, to facilitate operation of the generator <NUM>.

The controller <NUM> may have instructions operable upon execution by the processor <NUM> to determine a line-to-line voltage <NUM>. The line-to-line voltage <NUM> may be defined as shown in equations <NUM>-<NUM>. <MAT> <MAT> <MAT> , where the VAN is the phase voltage, which may be defined as a first phase voltage, between the phase voltage 121A and the neutral reference <NUM>, where the VBN is the phase voltage, which may be defined as a second phase voltage, between the phase voltage 121B and the neutral reference <NUM>, where the VCN is the phase voltage, which may be defined as a third phase voltage, between the phase voltages 121C and the neutral reference <NUM>. It should be appreciated that the first, second, and third voltages may be interchanged or redefined (e.g., first phase voltage is defined as the second phase voltage). In the circumstance where the generator <NUM> only generates one multiphase output, the line-to-line voltage is the absolute value of the peak-to-peak voltage with respect to neutral.

As such, the line-to-line, or line-to-neutral, voltages (|VAB|, |VBC|, |VCA|) may be directly measured, received, or calculated by the controller <NUM>. A maximum line-to-line voltage <NUM> may be determined by the controller <NUM> through maximum line-to-line instructions <NUM> stored on the digital storage <NUM>. The maximum line-to-line instructions <NUM> may be determined by equation <NUM>. <MAT> , where VDC is the expected output voltage of the direct current power supply <NUM> according to the maximum line-to-line voltage <NUM> based on phase voltages 121A, 121B, 121C. As such, the controller <NUM> can control the output voltage of the direct current power supply <NUM> without direct measurement. The maximum line-to-line voltage <NUM> may be offset or otherwise adjusted by a diode constant, KDIODE. The diode constant may be measured or estimated based on the configuration or rating of the direct current power supply <NUM> or otherwise.

As shown, the controller <NUM> may include a feedback loop as indicated by summation block <NUM> and voltage output setpoint <NUM>. The controller <NUM> may include gain and compensation instructions <NUM> to control the exciter winding driver <NUM>. Gain and compensation instructions <NUM> may output an oscillating signal <NUM> to the exciter winding driver <NUM> using pulse width modulation hardware or other modulation hardware (e.g., analog outputs). It should be appreciated that the driver may be operable to receive digital instructions as well. The oscillating signal <NUM> may be a pulse width modulation signal. The pulse width modulation signal may have a duty cycle based on the desired excitation voltage of the generator <NUM> to result in the required direct current output at the direct current link capacitor <NUM>. As an example, the voltage output setpoint <NUM> may be defined as the <NUM> volts. The duty cycle may be defined as the ratio between HIGH or TRUE and LOW or FALSE values of the oscillating signal <NUM>. The exciter winding driver <NUM> may be of any type, including solid state circuity operable to energize the exciter winding <NUM> to induce current in the exciter <NUM>.

Referring to <FIG>, phase voltages 121A, 121B, 121C are illustrated in accordance with one or more implementation of the present disclosure. A generator cycle <NUM> is shown, corresponding with one full electrical cycle <NUM> of the generator <NUM>. A peak-to-peak voltage <NUM> is illustrated where the phase voltages 121A, 121B, 121C are clamped, indicating conduction of the rectifier <NUM> and voltage change resistance by the direct current link capacitor <NUM>. Such clamping can limit the maximum voltage of the phase voltages 121A, 121B, 121C and enables a more accurate depiction of the direct current output voltage at the direct current link capacitor <NUM> by measurement of the phase voltages 121A, 121B, 121C. When the phase voltages 121A, 121B, 121C are clamped a direct current measurement to maintain the output voltage is redundant. Phase voltages 121A, 121B, 121C may become unclamped during very light loads, no-load, or off-load conditions (e.g., startup loads, transient loads, load-shedding). As an example, direct current load <NUM> may be a direct current bus of an aircraft supply various aircraft loads. As loads switch on and off, stored energy in the generator <NUM> is transferred to the direct current link capacitor <NUM>. As a result, the rectifier <NUM> may become reverse biased and the multiphase outputs unclamped. The controller <NUM> may lower the excitation voltage to decrease the output voltage of the generator <NUM>, placing the generator <NUM> in a potentially under-excited condition. In the under-excited condition, the generator <NUM> may be unable to respond quickly to subsequent load-on transients (e.g., large voltage drops during the transient). Instead of monitoring both the direct current output voltage at the direct current link capacitor <NUM> and the phase voltages 121A, 121B, 121C, requiring two or more sensing loops; peak-to-peak or line-to-line voltage may be used based on the phase voltages 121A, 121B, 121C being in a cut-off state. As such, the amount of sensing loops may be reduced.

As shown the line-to-line voltage |VAB| <NUM> is based on the absolute value of the first phase voltage 121A, VAN, less the second phase voltage 121B, VBN; the line-to-line voltage |VBC| <NUM> is based on the absolute value of the second phase voltage 121B, VBN, less the third phase voltage 121C, VCN; and the line-to-line voltage |VCA| <NUM> is based on the absolute value of the third phase voltage 121C, VCN, less the first phase voltage 121A, VAN. Controlling the exciter winding driver <NUM> with the maximum value of these results in ensuring under-excitation is avoided during offload while maintaining the quadratic mean <NUM> or voltage output of the direct current link capacitor <NUM> during a load-off. This generator <NUM> control and direct current power supply <NUM> control reduces the sensing loop requirements without under-excitation.

Referring to <FIG>, a method <NUM> is shown. The method <NUM> may include additional steps or omit steps. The method <NUM> may include steps that may be performed sequentially or simultaneously. In step <NUM>, the controller <NUM> receives phase voltages 121A, 121B, 121C. The phase voltages 121A, 121B, 121C may be received in any medium and by any mode. As a non-limiting example, the phase voltages 121A, 121B, 121C may be received as digital voltage values. As another, the phase voltages 121A, 121B, 121C may be received as direct or adjusted voltages directly from multiphase outputs 110A, 110B, 110C. A number of other implementations are contemplated in this disclosure.

In step <NUM>, the controller <NUM> determines a maximum line-to-line voltage <NUM> (|VAB|, |VBC|, |VCA|) based on the phase voltages 121A, 121B, 121C. Instructions may include a simple digital or analog comparator to determine the maximum line-to-line voltage <NUM>. As such, the controller <NUM> is programmed to operate the exciter winding driver <NUM> in step <NUM>. The operation may be based on any number of signals, including analog or digital signals. The operation may be based on an oscillating signal <NUM>. The oscillating signal <NUM> may be a pulse width modulation signal having a duty cycle sized to maintain an operating voltage threshold of the direct current power supply <NUM>. As such, the exciter winding driver <NUM> operates the excitation winding <NUM> to excite the generator <NUM>, according to the maximum line-to-line voltage <NUM>. DC electrical systems that use the rectified output of an AC generator traditionally require two voltage regulation loops; one on the DC side and one on the AC side of the rectifier. Two control loops are needed to deal with a load-off transient that leaves little or no load on the system. The technical effect of the present invention is that the invention can deal with load-off transients with a single control loop and this simplifies the voltage regulator design.

Claim 1:
A direct current power supply comprising:
an exciter (<NUM>) having an excitation winding (<NUM>) and operable to output an excitation voltage;
a generator (<NUM>) connected to the exciter and that generates a multiphase output having phase voltages based on the excitation voltage;
a rectifier (<NUM>) configured to receive the multiphase output and having diodes oriented to rectify multiphase output;
a direct current link capacitor (<NUM>) connected to an output of the rectifier that generates a direct current link capacitor voltage;
a controller (<NUM>) having an exciter winding driver, digital storage, and instructions stored on the digital storage operable upon execution by the controller to:
receive a phase voltage for each phase of the multiphase output;
define a maximum line-to-line voltage based on the phase voltages;
generate an oscillating signal according to the maximum line-to-line voltage; and
energize the exciter winding driver to drive the excitation winding based on the oscillating signal; and characterised in that:
the phase voltages define a quadratic mean that is maintained greater than the direct current link capacitor voltage during a load-off.