Fault detection for a semiconductor power converter

Abstract

Fault Detection for a Solid-State Power Converter In some examples, this disclosure describes a method for detecting a fault in a power supply system comprising a bus connected between a first solid-state power converter and a second solid-state power converter. The method comprises receiving, at a controller of the power supply system, a first signal indicating a current at the source side of the first solid-state power converter, wherein the source side of the first solid-state power converter is connected to a power source of the power supply system.The method also includes receiving, at the controller, a second signal indicating a current at the bus and determining, by the controller, that a fault has occurred in the electrical power system based on the first signal and further based on the second signal. The method further includes controlling the first solid-state power converter in response to determining that the fault has occurred. Figure for abstract: Fig. 1.

Description

Title of the invention: Fault detection for a semiconductor power converter Technical field

[0001] This disclosure relates to electrical power systems.

[0002] BACKGROUND

[0003] A power supply system may include one or more power sources and one or more loads separated by one or more solid-state power converters. In a bidirectional power supply system, a solid-state power converter may allow current to flow in both directions between the power source and the load. The solid-state power converter may include a set of source-side switches and a set of load-side switches, with an optional intermediate capacitor connected between the source-side switches and the load-side switches.

[0004] SUMMARY

[0005] This disclosure describes techniques for detecting a fault in an electrical power system that includes at least two solid-state power converters and at least two controllers. The controllers may be configured to receive signals indicative of current on the source side of the electrical power system, on the bus between the two converters, and on the load side of the electrical power system. Based on one or more of the received signals, one of the controllers may determine that a fault has occurred in the electrical power system.

[0006] The techniques of this disclosure may enable faster and more accurate detection of a fault, compared to existing techniques that use a signal received from a single sensor on a single solid-state power converter. A controller implementing the techniques of this disclosure may be able to determine the location of the fault, and the controller may be configured to disable some of the system switches to protect components from the fault.

[0007] In some examples, this disclosure describes a method for detecting a fault in an electrical power system comprising a bus connected between a first solid-state power converter and a second solid-state power converter. The method comprises receiving, at a controller of the electrical power system, a first signal indicating a current at the source side of the first solid-state power converter, wherein the source side of the first solid-state power converter is connected to a power source of the electrical power system. The method also includes receiving, at the controller, a second signal indicative of a current at the bus and determining, by the controller, that a fault has occurred in the electrical power system based on the first signal and further based on the second signal. The method further includes controlling, by the controller, the first solid-state power converter in response to determining that the fault has occurred.

[0008] In some examples, a system includes a first solid-state power converter including a first set of switches connected to a source side of the first solid-state power converter, a second set of switches connected to a bus side of the first solid-state power converter, and a first intermediate capacitor connected between the first set of switches and the second set of switches. The system also includes a second solid-state power converter including a third set of switches connected to a bus side of the second solid-state power converter, a fourth set of switches connected to a load side of the second solid-state power converter, a second intermediate capacitor connected between the third set of switches and the fourth set of switches.The system further includes a power source connected to the source side of the first solid-state power converter. The system includes a bus connected to the bus side of the first solid-state power converter and to the bus side of the second solid-state power converter. The system also includes a load connected to the load side of the second solid-state power converter.

[0009] In some examples, a device includes a computer-readable storage medium having stored thereon executable instructions configured to be executable by processing circuitry of the device to cause the processing circuitry to receive a first signal indicative of a current from the source side of a first solid-state power converter of a power supply system, wherein the source side of the first solid-state power converter is connected to a power source of the power supply system. The instructions are configured to be executable by the processing circuitry to further cause the processing circuitry to receive a second signal indicative of a current at a bus connected between the first solid-state power converter and a second power converter. semiconductor power converter of the power supply system. The instructions are further configured to be executable by the processing circuitry to further cause the processing circuitry to determine that a fault has occurred in the power supply system based on the first signal and further based on the second signal. The instructions are configured to be executable by the processing circuitry to also cause the processing circuitry to control the first semiconductor power converter or the second semiconductor power converter in response to determining that the fault has occurred.

[0010] Details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description and drawings, as well as the claims. Brief description of the drawings

[0011] [Fig-1] is a conceptual block diagram illustrating an electrical power system comprising a solid-state power converter and a controller, in accordance with one or more techniques of this disclosure.

[0012] [Fig.2] is a conceptual block diagram illustrating a power supply system comprising a bus connected between two solid-state power converters, in accordance with one or more techniques of this disclosure.

[0013] [Fig.3] illustrates the magnitude of electrical current associated with events that may occur in an electrical power system, in accordance with one or more techniques of this disclosure.

[0014] [Fig.4] is a plot of a current through a capacitorless solid-state power converter before and after a fault, in accordance with one or more techniques of this disclosure.

[0015] [Fig.5] is a plot of currents flowing through the source side, bus side, and load side of an electrical power system before and after a fault, in accordance with one or more techniques of this disclosure.

[0016] [Fig.6] and

[0017] [Fig.7] are plots of currents through an electrical power system with different capacitance values ​​for intermediate capacitors before and after a fault, in accordance with one or more techniques of this disclosure.

[0018] [Fig. 8 A],

[0019] [Fig.8B] and

[0020] [Fig.9] are flowcharts illustrating examples of processes for detecting a defect, in accordance with one or more techniques of this disclosure.

[0021] [Fig. 10] is a flowchart illustrating an exemplary process for selecting a capacitance of an intermediate capacitor, in accordance with one or more techniques of this disclosure.

[0022] [Fig. 11] is a flowchart illustrating an exemplary method of verifying the capacitance of an intermediate capacitor, in accordance with one or more techniques of this disclosure. DETAILED DESCRIPTION

[0023] This disclosure describes techniques for detecting a fault based on signals received from current sensors in an electrical power system. The techniques of this disclosure may be used by a controller in an electrical power system that includes at least two solid-state power converters with a bus connected between the converters. The controller may be configured to quickly detect the occurrence and / or location of a fault in the electrical power system using the techniques of this disclosure.

[0024] In some examples, a first controller receives a first current sense signal from a source side of a first solid-state power converter and a second current sense signal from a bus connected between the first solid-state power converter and a second solid-state power converter. A second controller may receive a third current sense signal from a load side of the solid-state power converter and a fourth current sense signal from the bus. The first and second controllers may be configured to detect a fault based on the magnitudes of one or more of the current sense signals. The controllers may also be configured to determine the location of the fault based on the magnitudes of the current sense signals.

[0025] The intermediate capacitor of the solid-state power converter(s) may be sized to allow for more efficient fault detection. In examples where the intermediate capacitor has a very small capacitance, there may be a very small difference between the magnitudes of the load-side current and the bus-side current for a load-side fault. Thus, increasing the capacitance may make detection easier for the respective controller. However, large capacitors with high capacitances increase the size, mass, and cost of the power supply system. A capacitance of the intermediate capacitor may be selected based on the parameters of the power supply system to allow relatively easy detection, while maintaining size and mass.

[0026] An existing controller for an electrical power system may use current waveforms or trigger thresholds for each converter branch. However, defining the current curve for each branch may be difficult because the electrical power system may be bidirectional, with the downstream transmission network having more or less power transmission capacity. For the electrical power system, it is possible to integrate and increase the number of distributed generators and loads in the current electrical power system. For this purpose, a controller may be configured to perform autonomous fault coordination by using a solid-state power converter with a decoupling capacitor.

[0027] In the event of a short-circuit fault on the load side, the nearest decoupling capacitor may discharge through the faulty load. Therefore, the current of the fault-side device will rapidly increase to the threshold level for the current to trigger the shutdown procedure. The other power converters in the healthy branches of the power system will see a relatively lower conduction current value and little impact from the fault. However, the current waveform for each branch is normally a time-varying variable as new distribution generation units or new loads are added to the power system.Therefore, a solid-state power converter with a decoupling capacitor can enable a controller to perform autonomous fault detection using system-level current curve information. The controller can be configured to collect location information to detect faults in the system.

[0028] [Fig. 1] is a conceptual block diagram illustrating a power supply system 100 including a solid-state power converter 120 and a controller 190, in accordance with one or more techniques of this disclosure. The controller 190 may be configured to activate and deactivate the switches 131-134 based on the electrical signals received by the controller 190 from the current sensors inside and outside the solid-state power converter 120. Other detailed examples of the arrangement and operation of the solid-state power converters are described in commonly assigned U.S. Patent No. 10,693,367, entitled “Pre-Charging Circuit for Power Converter,” filed February 19, 2019 and issued June 23, 2020, the entire contents of which are incorporated herein by reference.

[0029] The power supply system 100 is configured to provide electrical energy generated by the power source 110 to the load 170 via the solid-state power converter 120 and the bus 160. The solid-state power converter 120 is shown as including four switches 131-134, although other numbers and arrangements of switches are possible for the solid-state power converter 120. The switches 131-134 may include insulated-gate bipolar transistors, metal-oxide-semiconductor field-effect transistors (FETs), junction FETs, and / or any other transistor device. The switches 131-134 may include materials such as GaN and / or SiC and may include antiparallel diodes in some examples.The power supply system 100 includes a load capacitor 172 connected to the bus rails 160 in parallel with the load 170.

[0030] [Fig. 1] shows only one example of an electrical power system 100, and many other example electrical power systems may utilize the techniques described herein. For example, in some examples, the electrical power system 100 may be configured to operate in a reverse direction, where the electrical power system 100 includes a power source coupled to the bus 160 and a load coupled to the switches 131 and 132. In other examples, the electrical power system 100 is a bidirectional system where the power source 110 or the load 170 may operate as a power source and / or an electrical load. For example, the power source 110 or the load 170 may include a rechargeable battery, a motor-generator, and / or any other element that may operate as a power source or a load.To enable bidirectional operation, the power lines between the power source 110 and the switches 131 and 132 may comprise a bus.

[0031] The electrical power system 100 may include a microgrid, a mixed alternating current / direct current (AC / DC) system, an AC / AC system, a DC / DC system, an AC bus, a DC bus, and / or any other type of electrical system. The electrical power system 100 may also be part of a power generation system such as a power plant, a power distribution system, and / or a residential or commercial power system, which may include energy storage and electrical loads. The electrical power system 100 may be part of an aerospace, marine, or automotive system. The techniques of this disclosure may be particularly useful in electric vehicles, for example, for battery-disconnect systems in electric vehicles. The electrical power system 100 may be part of a vehicle such as any any air, land, sea, or space vehicle, with or without crew, which may include an engine, generator, alternator, and / or power distribution system.

[0032] The power source 110 may be configured to generate electrical energy. The power source 110 may include an electrical generator that converts mechanical energy derived from a shaft, rotor, and / or other mechanical component into electrical energy for use by other components or circuits of the electrical power system 100. In some examples, the electrical generator may also be mounted on a mechanical distribution system and / or a mechanical transmission system (for clarity of the drawings, neither of these systems is shown). In some examples, the electrical power system 100 may include one or more additional power sources, although not shown in [Fig. 1]. The power source 110 may include an alternating current generator such as an induction generator or a direct current generator that produces direct current electricity.The power source 110 may include a wound field machine, a Halbach array generator with permanent magnets on a rotor that is driven by a motor shaft or a propeller shaft, or any other type of generator.

[0033] The power source 110 may, in some examples, generate alternating current electricity (e.g., multi-phase alternating current electricity), and the power supply system 100 may include a power converter to generate direct current electricity based on the power generated by the power source 110. The power converter may be a rectifier circuit that converts AC electricity to DC electricity. The power source 110 may be connected to the source-side switches 131 and 132 by power lines. These power lines may include line inductors 156 and 157 that affect the conduction of electricity along the power lines. The integrated inductors 151 and 152 may also affect the conduction of electricity along the power lines.

[0034] The solid-state power converter 120 is connected between the power source 110 and the load 170. The solid-state power converter 120 may include two source-side switches 131 and 132 and two load-side switches 133 and 134. The solid-state power converter 120 also includes an intermediate capacitor 140 connected between the source-side switches 131 and 132 and the load-side switches 133 and 134. A fault may occur on the source side of the solid-state power converter 120, for example, by occurring on a power line between the power source 110 and one of the switches 131 and 132. A fault may occur on the load side of the solid-state power converter 120, for example, by occurring on a power line between the load 170 and one of the switches 133 and 134. The fault may occur for many potential reasons, including breakdown of the insulation of a power line and / or failure of a switch or capacitor.

[0035] The bus 160 may operate as a direct current bus, where the voltage level on each of the rails is a direct current value during normal operation. The target voltage level across the bus 160 may be several tens or hundreds of volts, such as 28 volts, 270 volts, 540 volts, or 750 volts in some examples. The voltage level across the bus 160 may also be lower or higher than the voltage generated by the power source 110. To increase the voltage level across the bus 160, the controller 190 may control the solid-state power converter 120 to transfer power from the power source 110 to the bus 160.

[0036] The load 170 may include a power converter configured to convert power received from the power source 110 into another form of electricity for an electrical load (not shown in [Fig.l]). The power converter may produce electrical energy in a form usable by an electrical load. For example, the load 170 may include an inverter configured to convert direct current electricity received by the load 170 into alternating current electricity for an electric motor. In some examples, the electrical power system 100 may include a load that takes electricity directly from the bus 160 without a converter. The load 170 and the load capacitor 172 may be connected to the load-side switches 133 and 134 by power lines.These power lines may include line inductors 158 and 159 that affect the conduction of electricity along the power lines. The solid-state power converter 120 may also include additional integrated inductors 153 and 154 that slow the rise of current during a short-circuit fault.

[0037] The load capacitor 172 may be coupled between the rails of the bus 160. The energy generated by the power source 110 that the bus 160 receives from the solid-state power converter 120 may be filtered by the load capacitor 172. The load capacitor 172 may act as a low-pass filter for the energy transferred from the power source 110 to the bus 160. The load capacitor 172 may filter the ripple generated by the power source 110 or by the load 170 by preventing the ripple currents from returning to the power source 110 and by smoothing the variations in the voltage across the bus 160.

[0038] The controller 190 may be configured to control the operation of the solid-state power converter 120 and any of the sensors of the electrical power system 100. Additionally or alternatively, the controller 190 may be configured to control the operation of the power source 110 and / or the load 170. For example, the controller 190 may control the operation of the load 170 by providing control signals to the switches of the converters of the load 170. The controller 190 may be configured to control an operating mode of the solid-state power converter 120 to provide power to the bus 160 and / or the load 170. The controller 190 may also be capable of enabling or disabling the power source 110 or otherwise controlling an operating mode of the power source 110 to provide different levels and / or types of power.

[0039] The controller 190 may include processing circuitry 192, which may include any suitable arrangement of hardware, software, firmware, or any combination thereof, to perform the techniques attributed to the controller 190 herein. Examples of processing circuitry 192 include one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), full-authority digital electronic engine control units (FADECs), engine control units (ECUs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuits, as well as any combination of these components.When the processing circuitry 192 includes software or firmware, the processing circuitry 192 further includes any hardware for storing and executing the software or firmware, such as one or more processors or processing units. In examples where the electrical power system 100 is mounted on a vehicle, the controller 190 may be implemented by a FADEC unit.

[0040] In general, a processing unit may include one or more microprocessors, DSPs, ASICs, FPGAs, or other equivalent integrated or discrete logic circuits, as well as any combination of these components. Although not shown in [Fig. 1], the controller 190 may include memory configured to store data. The memory may include any volatile or non-volatile medium, such as random access memory (RAM), read only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, and any similar medium. In some examples, the memory may be external to the controller 190 (e.g., it may be external to a housing in which the controller 190 is housed). The processing circuitry 192 may be configured to determine whether a signal is above or below a threshold level. For example, the Processing circuitry 192 may include circuitry (e.g., digital or analog) and / or instructions for performing thresholding operations.

[0041] The controller 190 may output control signals to a control terminal of each of the switches 131-134 to activate or deactivate each of the switches 131-134. The controller 190 may be configured to control the solid-state power converter 120 based on the signals received from the sensors to achieve a target voltage or to implement a startup routine or a shutdown routine. By controlling the switches 131-134, the controller 190 may be able to control the charging and discharging of the capacitors 140 and 172 and the bus 160.

[0042] For example, by controlling switches 131-134, controller 190 may connect power source 110 and intermediate capacitor 140 to charge intermediate capacitor 140. Controller 190 may activate switches 131 and 132 and deactivate switches 133 and 134 to connect intermediate capacitor 140 to power source 110 and simultaneously isolate intermediate capacitor 140 from bus 160 and load 170. Controller 190 may deactivate switches 131 and 132 and activate switches 133 and 134 to connect intermediate capacitor 140 to bus 160 and load 170 and simultaneously isolate intermediate capacitor 140 from power source 110.Therefore, the intermediate capacitor 140 may help decouple the load from the load capacitor 172 and also help decouple a downstream network fault (e.g., occurring on the load side) from an upstream network (e.g., on the source side). The intermediate capacitor 140 may also delay the rise of current on the source side of the power system 100 in response to a load-side fault and delay the rise of current on the load side of the power system 100 in response to a source-side fault. Although described as an "intermediate" capacitor, the intermediate capacitor 140 is not necessarily positioned in the center of the solid-state power converter 120.

[0043] In some examples, the intermediate capacitor 140 may comprise an array of switchable capacitors connected in parallel. The controller 190 may be configured to adjust or set the capacitance of the intermediate capacitor 140 by connecting or disconnecting capacitors from the array. For example, to increase the capacitance of the intermediate capacitor 140, the controller 190 may activate one or more transistors to connect additional capacitors from the array, where each transistor may be connected in series with one of the capacitors in the array. Similarly, to reduce the capacitance of the intermediate capacitor 140, the controller 190 can turn off switches to connect additional capacitors from the network.

[0044] To activate one of the switches 131-134, the controller 190 may deliver an enable control signal to the control terminal of the respective switch. In response to receiving the enable control signal, the respective switch may close and allow current to flow across the switch (e.g., between the load terminals of the switch). The enable control signal, along with a voltage difference across the respective switch, may cause or facilitate the flow of electricity across the respective switch. To deactivate one of the switches 131-134, the controller 190 may deliver a deactivate control signal to the control terminal of the respective switch. In response to receiving the deactivate control signal, the respective switch may open and prevent current from flowing across the switch.

[0045] [Fig. 2] is a conceptual block diagram illustrating a power supply system 200 including a bus 260 connected between two solid-state power converters 220A and 220B, in accordance with one or more techniques of this disclosure. Controllers 290A and 290B may be configured to activate and deactivate switches 231A-234A and 231B-234B based on electrical signals received by controller 290 from current sensors and / or any other sensors. Other voltage sensors that transmit signals to controllers 290A and 290B include voltage sensors for detecting collector-emitter voltages or drain-source voltages of switches 231A-234A and 231B-234B. The signals received by the controllers 290A and 290B from the current sensors may indicate the current through a respective one of the switches 231A, 233A, 231B and 233B.

[0046] The electrical power system 200 is configured to provide electrical power generated by the power source 210 to the bus 260 via the solid-state power converter 220A. The electrical power system is also configured to provide electrical power from the bus 260 to the load 270 via the solid-state power converter 220B. In some examples, the electrical power system 200 is a bidirectional system where the power source 210 or the load 270 may operate as a power source and / or an electrical load. For example, the power source 210 or the load 270 may include a rechargeable battery, a motor-generator, and / or any other element that may operate as a power source or a load. As shown in [Fig. 2], the electrical power system 200 includes a power source and a load, but in some examples, the power supply system 200 may also include one or more additional power sources and / or one or more additional loads.

[0047] Each of the solid-state power converters 220A and 220B may include inductors 251-254, which may include transmission line inductors that affect the conduction of electricity along the power lines of the power system 200. The inductors 251-254 may be discrete inductors and / or may represent the parasitic inductances of the power system 200. Each of the inductors 251-254 may withstand a change in current in a power line. Thus, the characteristics of the inductors 251-254 may affect the rate at which the current detected by each of the sensors reaches a threshold level for a current during or after the occurrence of a fault, where the controller 290 may use the threshold level to detect the occurrence of a fault and the location of the fault.Inductors 251-254 can be used to limit the current rise during a short circuit fault.

[0048] A fault that occurs on the load side of the solid-state power converter 220B, for example, may draw current from the intermediate capacitor 240B through the switch 233B and the inductor 254. When the intermediate capacitor 240B discharges, the intermediate capacitor 240B may draw current from the bus 260 by means of the switch 231B and the inductor 253. The load-side fault may first cause a change in the current at a load-side sensor and eventually cause changes in the currents at other sensors. Similarly, a fault that occurs on the source side of the solid-state power converter 220A, for example, may draw current from the intermediate capacitor 240A by means of the switch 231A and the inductor 251.The source-side fault may first cause a change in current at one source-side sensor, and then cause changes in currents at other sensors.

[0049] The load side of the power supply system 200 may include switches 233B and 234B, inductor 254, load 270, and load capacitor 272. The source side of the power supply system 200 may include switches 231A and 232A, inductor 251, and power source 210. The source side may be referred to as "upstream," and the load side may be referred to as "downstream." The bus side of the power supply system 200 may include switches 233A, 234A, 231B, 232B, inductors 252 and 253, and a resistor 262.

[0050] Microgrid power distribution is a critical technology for the aerospace and maritime industries, among others. Solid-state power converters can provide power control and protection in a microgrid. A controller for a solid-state power converter may be able to detect a fault in the system based on a current rating or high-speed communication between converters. The current and power ratings of a solid-state power converter may be predetermined or fixed values ​​for a power transmission network. The current rating may be expressed as an exponent of the current (e.g., a square) that is a multiple of time, which may represent the severity of the fault. The current rating may be used to classify protective devices in an electric power system.

[0051] However, other distributed power sources and other loads may be added to an electrical power system during the lifetime of the system. The addition of multiple power sources increases the complexity of the system. For example, depending on the system layout, the downstream current rating may be even greater than the upstream current rating in a bidirectional power flow network.

[0052] In accordance with various aspects of the techniques of the present disclosure, the controller 290A or 290B may be configured to use locally sensed information to detect a fault, which may enable rapid processing times by eliminating network and central processing delays. For example, the controller 290B may be configured to determine that a fault has occurred in the power system 200 based on the magnitudes of signals received from the sensors in the solid-state power converter 220B. The techniques of this disclosure may eliminate the need for a common controller in the power system 200 to control both solid-state power converters 220A and 220B.In some examples, the solid-state power converters 220A and 220B may be distributed and separated along the long bus cable 260 such that current measurements from the solid-state power converter 220A may not be available to the controller 290B.

[0053] Controllers 290A and 290B may include processing circuitry configured to determine on which side or portion of the power system 200 a fault has occurred in response to determining that the amplitude of a signal from one side of the power system 200 is greater than a threshold level but the amplitude of a signal from the other side of the power system 200 is not greater than the threshold level. In this way, the controllers 290A and 290B may perform various aspects of fault detection techniques in the power system 200.

[0054] To this end, the controllers 290A and 290B may be able to protect the power system 200 by isolating the positive and negative buses from the bus 260 or other power lines independently in the event of a short circuit or ground fault. The controllers 290A and 290B may be configured to perform coordination against autonomous fault detection / protection against upstream and downstream short circuit faults while preventing false trips due to transient events caused by load changes and other non-fault events. In addition, the intermediate capacitors 240A and 240B allow for isolated charging of the line from the charging capacitor 272.The capacitance of the 240A and 240B intermediate capacitors can be selected during a design process based on the characteristics of the power system to facilitate autonomous fault detection.

[0055] The controllers 290A and 290B may be configured to perform autonomous fault detection with unidirectional or bidirectional solid-state power converters. For example, the controllers 290A and 290B may be configured to perform bidirectional control of current flow between the power source 210 and the load 270, which also allows for power transfer and protection capability against various fault conditions. In each positive and negative rail of the solid-state power converter 220A or 220B, the two antiparallel diode switching devices are connected in a common-emitter configuration.

[0056] The techniques of this disclosure may be used alone or in combination to provide redundancy and cross-checking for fault detection and localization. The techniques of this disclosure may also be used in combination with existing methods for additional redundancy and cross-checking. Additionally or alternatively, the controllers 290A and 290B may be configured to use safety disablement techniques to limit the exposure of the electrical power system 200 to a fault.

[0057] [Fig. 3] illustrates the magnitude of electrical current associated with events that may occur in an electrical power system, in accordance with one or more techniques of this disclosure. According to [Fig. 3], normal load transient events create the lowest magnitude of current increase. Examples of normal load events include an increase in power consumption due to normal operation and an increase in motor load speed.

[0058] Large load transient events can create larger amplitude current increases in an electrical power system. Large load transient events can be caused by the start-up or reconnection of a load which can cause a transient inrush current. But large load transient events should not trigger the trip signal of these switches. Low resistance fault transient events are capable of creating the largest current increases in an electrical power system. Examples of low resistance faults include short circuit faults and ground faults, such as short circuits to ground or to the high voltage side power supply.

[0059] [Fig.4] is a plot of a 400 current through a power converter semiconductor power converter without an intermediate capacitor before and after a fault, in accordance with one or more techniques of this disclosure. Before the fault occurs at time zero, the current 400 is approximately 140 amperes. When the fault occurs at time zero, the current 400 increases rapidly from 140 amperes. The current 400 can represent the current detected on both sides of a semiconductor power converter without an intermediate capacitor, since the current should be equal on both sides in examples where no intermediate capacitor is connected. Figures 4 and 5 show example current waveforms for cases 1 and 2 of Table I below.

[0060] [Tables 1] Case Inductances 253 and 254 Mid cap 2 40B Ifhreshold Comments 1 5 qH not available 580 A No autonomous fault coordination 2 5 qH 1 qH 580 A Fault coordination correct 3 10 qH 1 qH 580 A Fault coordination incorrect 4 10 qH 2 qH 580 A Fault coordination correct

[0061] Table I: Example Parameters for Power System 200

[0062] [Fig. 5] is a plot of currents 500, 510, 520 through the source side, bus side, and load side of a power system before and after a fault, in accordance with one or more techniques of this disclosure. The example waveforms shown in [Fig. 5] are detected in a power system electrical circuit that includes an intermediate capacitor in a solid-state power converter. Before the fault occurs at time zero, currents 500, 510, and 520 are all approximately 140 amperes. When the fault occurs at time zero, current 500 increases more slowly than currents 510 and 520.

[0063] Using the power supply system 200 shown in [Fig. 2] as an example, the fault may occur on the load side of the power supply system 200. For example, the fault may occur at the load 270 or across the load capacitor 272. Current 500 represents the source-side current of the solid-state power converter 220A shown in [Fig. 2]. Current 510 represents the bus current at the bus 260, and current 520 represents the load-side current of the solid-state power converter 220B. Since current 520 is closest to the fault occurrence, current 520 increases most rapidly after the fault occurrence.

[0064] In the example shown in [Fig. 5], currents 500 and 520 increase at different rates due to the fault. Controllers 290A and 290B may be configured to implement a threshold level of 580 amps for currents 500, 510, and 520. Current 520 increases rapidly to the threshold level of 580 amps to trigger switches 233B and 234B, while current 500 remains at a relatively low value (e.g., 250 amps) with lesser impacts for switches 231A-234A. Switches 233B and 234B may be triggered when controller 290B deactivates switches 233B and 234B in response to exceeding a threshold level.

[0065] The controller 290B may be configured to determine that a fault has occurred on the load side of the power system 200 by determining at least that an amplitude of the signal received from the sensor in or near the solid-state power converter 220B (e.g., waveform 520) is greater than a first threshold level. Further, the controller 290B may be configured to determine that the fault has occurred by determining at least that an amplitude of the signal received from one or more sensors is not greater than a second threshold level. The first and second threshold levels may be the same or different.

[0066] In response to determining that a fault has occurred on the load side of the power system 200, the controller 290B may be configured to disable switches 233B and 234B to isolate the power source 210 and the bus 260 from the fault. In some examples, the controller 290B may be configured to first disable switches 23IB and 232B to allow the intermediate capacitor 240 to discharge to the load side of the power system 200 before disabling switches 233B and 234B. The controller 290B may be configured to disable switches 233B and 234B in response to determining that the voltage across the intermediate capacitor 240 is sufficiently low (e.g., below a threshold level).

[0067] In examples in which the controller 290B deactivates the switches 233B and 234B in response to determining that a fault has occurred on the load side, the controller 290B may be configured to subsequently determine whether the switches 233B and 234B are actually deactivated. It may be that the switch 233B or 234B is not actually deactivated due to a short circuit on the load path of the switch 233B or 234B, a failure of the control circuit of the switch 233B or 234B, and / or a disconnection between the control circuit and the switch 233B or 234B. Controller 290B may be configured to determine whether switches 233B or 234B are actually deactivated by measuring the current through or voltage across switches 233B or 234B.The controller 290A may also determine whether the current through the solid-state power converter 220A is greater than a threshold level based on the signal(s) received by the controller 290A from current sensors in or near the solid-state power converter 220A.

[0068] In response to determining that one or both of switches 233B and 234B are still active and determining that the current through the solid-state power converter 220B is above a threshold level, the controller 290B may disable the bus-side switches 231B and 232B. Disabling the bus-side switches 231B and 232B further isolates the fault from the power source 210 in examples where the load-side switches 233B and 234B still allow current to flow through the power system 200. Thus, the controller 290B may be configured to implement safety techniques in examples where the switches 233B and 234B cannot disable.

[0069] Additionally or alternatively, the controller 290A may be configured to determine that a fault has occurred on the source side of the power system 200 by determining at least that an amplitude of the signal received from a source-side sensor (e.g., waveform 500) is greater than a first threshold level. Further, the controller 290A may be configured to determine that the source-side fault has occurred by determining at least that an amplitude of the signal received from a bus-side sensor is not greater than a second threshold level. The first and second threshold levels may be the same or different.

[0070] Figures 6 and 7 are plots of currents 600, 610 and 620 through a power supply system with different capacitance values ​​for intermediate capacitors before and after a fault, in accordance with one or more of the following: several techniques of this disclosure. In the example shown in [Fig. 6], current 620 does not reach the threshold level of 580 amperes until current 600 reaches the threshold level. The waveforms of currents 600, 610, and 620 are based on inductances 251-254 and the capacitances of intermediate capacitors 240A and 240B. For example, the different waveforms of Figures 5 and 6 may be due to an increase in each of the transmission line inductances 251-254 from five microhenries to ten microhenries, even though the other parameters remain the same in both examples.

[0071] Other parameters of the power supply system 200 shown in Table I may include the capacitances of the intermediate capacitors 240A and 240B, the voltage generated by the power source 210, and the threshold level for fault detection. The voltage generated by the power source 210 may be a battery voltage or the output of a power converter such as a rectifier or a DC / DC converter. The threshold level may be set based on the damage that may occur to the components of the power supply system 200 at various current levels.

[0072] In the example of [Fig. 6] (case 3 in Table I), the capacitance of the intermediate capacitor 240B may have been incorrectly sized and selected given the threshold current level of 580 amps. The controller 290A may be configured to generate a false alarm on the source side of the power system 200 because current 600 reaches the threshold level of 580 amps before currents 610 and 620 reach the threshold level, even though the fault occurred on the load side. Thus, using a threshold level of 580 amps for the waveforms shown in [Fig. 6] would result in the load side fault being incorrectly detected as a source side fault.

[0073] An existing power system that has the current waveforms shown in [Fig. 6] would use a threshold level matched to the current waveform to improve fault detection, rather than sizing an intermediate capacitor to improve fault detection. The techniques described herein allow the threshold level to be set based on the damage that may occur to the system components and then the capacitance of the intermediate capacitor to be selected to enable effective fault detection. The selection of the capacitance of the intermediate capacitor can be based on the threshold level already determined.

[0074] In the example shown in [Fig.7], current 720 reaches the threshold level of 580 amperes before currents 700 and 710 because the capacitance of the intermediate capacitor 240B is appropriately sized. As shown in Table I, the capacitance of the intermediate capacitor 240B has been increased by one micro-farad to two micro-farads, which allows the intermediate capacitor 240B to supply more current to the fault on the load side of the power system 200.

[0075] Figures 8A, 8B and 9 are flowcharts illustrating example processes of detecting a fault, in accordance with one or more techniques of this disclosure. The techniques of Figures 8A, 8B, and 9 are described with reference to the controller 290A shown in [Fig. 2], but the techniques of Figures 8A, 8B, and 9 may also be performed by the controller 290B shown in [Fig. 2] or the controller 190 shown in [Fig. 1]. The controllers 190, 290A, and 290B may be configured to perform any of the operations 800A-806A and 800B-806B shown in Figures 8A and 8B, any of the operations 900-912 shown in [Fig. 9], or any other technique described in connection with Figures 8A, 8B, and 9.

[0076] In the example of [Fig.8A], the controller 290A receives a first signal from a source-side sensor indicating a current at the source side of the solid-state power converter 220A (800A). In addition, the controller 290A receives a second signal from a bus-side sensor indicating a current at the bus 260 (802A). Each of the first and second signals may indicate a voltage across a shunt resistor, the output of a current mirror, the output of a Hall effect sensor, and / or the output of a magnetoresistive sensor.

[0077] In the example of [Fig. 8A], the controller 290A determines that a fault has occurred in the electrical power system 200 based on the first and second signals (804A). For example, the controller 290A may be configured to detect a fault by determining at least that an amplitude of one or more of the first and second signals is greater than a threshold level. The controller 290A may use the same or different threshold levels for each of the first and second signals. For example, the controller 290A may be configured to determine the location of a fault by determining at least that the amplitude of one signal is greater than a first threshold level and the amplitude of another signal is less than a second threshold level, where the second threshold level is less than the first threshold level.In examples where the amplitude of one signal is much higher than the amplitude of another signal, the controller 290A may be able to confirm the location of a fault. For example, at the time current 620 reaches the threshold level of 580 amps in [Fig. 6], currents 600 and 610 are several hundred amps below the threshold level, indicating that the fault occurred on the load side of the electrical power system 200.

[0078] In the example of [Fig.8A], the controller 290A controls the solid-state power converter 220A in response to determining that the fault has occurred. product (806A). The controller 290A may be configured to disable one or more switches of the solid-state power converter 220A in response to determining that the fault has occurred. In examples in which the controller 290A determines that the fault has occurred on a source side of the power system 200, the controller 290A may be configured to disable switches 231A and 232A to isolate the bus 260 from the fault.

[0079] In the example of [Fig. 8B], the controller 290B receives a first signal from a load-side sensor indicating a current on the load side of the solid-state power converter 220B (800B). Further, the controller 290B receives a second signal from a bus-side sensor indicating a current at the bus 260 (802B). The controller 290B determines that a fault has occurred in the power system 200 based on the first and second signals (804A). For example, the controller 290B may be configured to detect a fault by determining at least that an amplitude of one or more of the first and second signals is greater than a threshold level. The controller 290B may use the same or different threshold levels for each of the first and second signals.

[0080] In the example of [Fig.8B], the controller 290B controls the solid-state power converter 220B in response to determining that the fault has occurred (806B). The controller 290B may be configured to disable one or more switches of the solid-state power converter 220B in response to determining that the fault has occurred. In examples in which the controller 290B determines that the fault has occurred on a load side of the power system 200, the controller 290B may be configured to disable switches 233B and 234B to isolate the bus 260 from the fault.

[0081] In the example of [Fig.9], the controller 290A receives the first and second current sensor signals in or near the solid-state power converter 220A (900, 902). The controller 290A then determines whether the first signal is above a threshold level and whether the second signal is below the threshold level (904). In response to this determination, the controller 290A disables the source-side switches 231A and 232A to isolate the fault on the source side of the solid-state power converter 220A (906). Additionally or alternatively, in response to this determination, the controller 290A may disable the switches 233A and 234A.

[0082] In response to determining that the condition of step 904 is not satisfied, controller 290A determines whether the second signal is greater than a threshold level and whether the first signal is less than the threshold level (908). In response to this determination, controller 290A disables bus-side switches 233A and 234A to isolate the fault on the load side of the semi-automatic power converter. 220A (910) conductors. Additionally or alternatively, in response to this determination, controller 290A may disable switches 231A and 232A.

[0083] [Fig. 10] is a flowchart illustrating an exemplary process for selecting a capacitance of an intermediate capacitor, in accordance with one or more techniques of this disclosure. The techniques of [Fig. 10] are described with reference to the intermediate capacitor 140 shown in [Fig. 1], but the techniques of [Fig. 10] may be performed for intermediate capacitors 240A and / or 240B shown in [Fig. 2].

[0084] In the example of [Fig. 10], the inductances 251-254 are determined on both sides of the semiconductor power converters 220A and 220B (1000). The inductances of the transmission lines 251-254 may be determined by monitoring the variation of the current over time in response to a variation of the voltage. The voltage level generated by the power source 210, or the voltage level output by a converter connected to the power source 210, may also be determined (1002). The threshold level for the current in the entire power supply system 200 may be set based on the characteristics of the power supply system 200 (1004). For example, the insulation of a power line may burn out or one of the switches 231A-234A and 231B-234B may fail above a particular current level.A capacitance of the intermediate capacitor 240A or 240B can be determined based on the inductances 251-254, the voltage level delivered by the power source 210, and based on the threshold level for the current.

[0085] Equations (1)-(18) provide a basic example for determining a capacitance of the intermediate capacitor 240A or 240B. Equations (1)-(7) provide the mathematical relationships between the inductors 251-254 and the currents and voltages through the power supply system 200. The voltage across an inductor is proportional to the change in current through the inductor, r ^21 — y _ v (1) ^251 dt “ ^210 ^ 240.4 | 2404 (2) ^251-^252^^240^ dt T ^52 _ yy (3) ^252 dt “ 240A v 260 j - i _|_ (4) ^252“ ^253' K262 t .^2.53 _y _ y (5) l253 dt - ^260 v240B ; — j J. r dv24w (6) ^253-^254^^2405 dt r .^254 _ yy (7) L254 dt “ v240B v272

[0086] Assuming normal operation of the power supply system 200 as the initial condition, a downstream short circuit fault (e.g., on the load side of the power supply system 200) may force the voltage across the load capacitor 272 to zero volts. A few microseconds after the downstream short circuit fault, the magnitude of the DC current in the inductors 251-254 will begin to increase. However, the current detected by a load side sensor is different from the current detected by a bus side sensor due to the LCR resonant circuit that includes the inductors 251-254, the intermediate capacitors 240A and 240B, and the resistor 262.The different rates of current rise can provide an indication of the location of the fault (e.g., on the downstream side, load side), and the controller 290B can turn off the switches 233B and 234B immediately without affecting the power supply to the upstream load because the switches 231A-234A, 23 IB and 232B remain in normal operation. Thus, the controller 290 . may be able to immediately clear the fault of the downstream load circuit without affecting the upstream resistor 262 too much. Therefore, the voltage across resistor 262 is assumed to be the same as under normal operating conditions. Based on the assumptions mentioned above, the following circuit equations (8) and (9) are derived. Table II shows some of the simulation parameters for an example power supply system. T ^254 _ y (8) ^254 dt “ 240B T ^53 _ yy (9) ■“253 dt “ 210 240B

[0087] [Tables2] Parameter Example value V240B 270 volts L251 to L254 to vary (L253 = L254) C240A 1 micro-farad C240B to optimize with respect to L251 to L254 C272 500 micro-farads R262 100 ohms R270 7.7 ohms

[0088] Table II: Simulation parameters for the power supply system 200

[0089] By combining equations (6), (8) and (9), we obtain equations (10) and (11). t U?40B ^253^2405 + p + lStr 240B- V210 (10) — J^2W I .^210 g4p 4- y 240B- 2'2 5111 cx 1+f^ ______L254 ^253^2405 (H)

[0090] Equations (12) and (13) provide analytical equations for the currents passing through the power supply system 200. (13)

[0091] A short-circuit fault that occurs on the load side should be triggered at the time when the current detected by the sensor 244 reaches the threshold value Ithreshoid while the current detected by the sensor 243 still remains at a relatively low value. In response to the detection of the load-side fault, the controller 290 will only turn off the switches 233B and 234B while the other switches 231A-234A, 23 IB and 232B will not be affected. In this way, the downstream short-circuit fault is detected and isolated by the controller 290. The optimal treat is selected using equation (14) when equations (15) and (16) are valid. f — 3 / -^253^2405- (14) _ / H-2 \ ^dc 1^253^2403 (^) ^253-( 2 / 2L253 U f i-254

[0092] / y — g+2 ] v of J254— 2 2 /

[0093] For the controller 290B to perform a fault detection method based on the current detected by a load-side current sensor for autonomous detection of upstream and downstream short-circuit faults. Accordingly, the intermediate capacitor 240B can be sized to provide sufficient delay as shown in equations (17) and (18). t _ j H+2 I ^210 / ^253^2403 * threshold I 2 l2L7r<5u j \ I î ^254 p — i fi x i+7^ )l? cq ^2405--^^2^+2),1 253

[0094] Equation (18) provides a basis for determining a size or capacitance of the capacitor 240B based on the threshold current level, based on the voltage generated by the power source 210, and further based on the inductances 253 and 254. For example, the capacitance of the intermediate capacitor 240B may be proportional to the inductance 253 and the square of the threshold level of the current. The capacitance of the intermediate capacitor 240B may be inversely proportional to a square of the voltage generated by the power source 210 or inversely proportional to a square of the voltage generated by a power converter connected to the power source 210. Equation (19) is a generic form of equation (18) where D1, D2 and D3 are constant values ​​that may be adjusted based on test results or other considerations. F» xz (^threshold ] ( 77_ J--77„ (^) ^2405 = D1X (.....J M53 + ^3

[0095] [Fig. 11] is a flowchart illustrating an exemplary method of verifying the capacitance of an intermediate capacitor, in accordance with one or more techniques of this disclosure. The techniques of [Fig. 11] are described with reference to the controller 290A shown in [Fig. 2], but the techniques of [Fig. 11] may also be performed by the controller 290B shown in [Fig. 2] or by the controller 190 shown in [Fig. 1]. The controllers 190, 290A, and 290B may be configured to perform any of the operations 1100-1108 shown in [Fig. 1 1], or any other technique described in connection with [Fig. 1 1].

[0096] In the example of [Fig. 11], the controller 290A operates the solid-state power converter 220A with a particular duty cycle (1100). The controller 290A then receives signals from sensors in the power supply system 200, where the signals indicate electrical parameters such as voltage and current in the power supply system 200 during operation of the solid-state power converter 220. The controller 290A estimates the values ​​of the inductors 251 and 252 based on the received signals (1102). For example, the controller 290A may be configured to determine an estimated value of the inductor 251 based on the switching frequency and duty cycle of the switches 231A-234A. The controller 290A also determines a desired capacitance of the intermediate capacitor 240A based on the DC voltage generated by the power source 210, of the threshold current for the converter of 220A semiconductor power, and estimated values ​​of inductors 251 and 252(1104).

[0097] In the example of [Fig. 11], the controller 290A compares the desired capacitance of the intermediate capacitor 240A to an actual capacitance of the intermediate capacitor 240A (1106). The actual capacitance value of the intermediate capacitor 240A may be stored in memory, or the controller 290A may be configured to determine the actual capacitance by testing. In response to the comparison of the desired and actual capacitances, the controller 290A generates an output (1108). For example, the controller 290A may be configured to transmit an alert to another device, where the alert indicates that the actual capacitance is outside an acceptable range of desired capacitances. Additionally or alternatively, the controller 290A may be configured to adjust the actual capacitance of the intermediate capacitor 240A by connecting or disconnecting the switchable capacitors of the solid-state power converter 220A.The switchable capacitors may allow the capacitance of the intermediate capacitor 240A to be adjusted. The controller 290A may be configured to also determine an updated value for the threshold current based on the voltage generated by the power source 210, the capacitance of the intermediate capacitor 240A, and the estimated values ​​of the inductors 251 and 252.

[0098] The techniques of [Fig.l 1] may allow for self-checking and online monitoring of the capacitance of the intermediate capacitor 240A during operation of the solid-state power converter 220A. By self-checking the capacitance of the intermediate capacitor 240A, the controller 290A may confirm that the threshold current is set at an appropriate value for fault detection. For example, during the lifetime and operation of the solid-state power converter 220A, the grid impedance may change due to the addition or removal of circuits, loads, power sources, and / or converters. A change in the grid impedance may cause the set parameters to mismatch, which may cause the controller 290A to adjust the capacitance of the intermediate capacitor 240A or generate an alarm in response to detecting the change.

[0099] The following numbered examples illustrate one or more aspects of the disclosure.

[0100] Example 1. A method for detecting a fault in a power supply system comprising a bus connected between a first solid-state power converter and a second solid-state power converter. The method comprises receiving, at a controller of the power supply system, a first signal indicative of a current at the source side of the first solid-state power converter, wherein the source side of the first solid-state power converter is connected to a source power supply of the electrical power system. The method also includes receiving, at the controller, a second signal indicating a current at the bus and determining, by the controller, that a fault has occurred in the electrical power system based on the first signal and further based on the second signal. The method further includes controlling, by the controller, the first solid-state power converter in response to determining that the fault has occurred.

[0101] Example 2. A method for detecting a fault in a power supply system comprising a bus connected between a first solid-state power converter and a second solid-state power converter. The method comprises receiving, at a controller of the power supply system, a first signal indicative of a current at the bus and a second signal indicative of a current at a load side of the second solid-state power converter, wherein the load side of the first solid-state power converter is connected to a load of the power supply system. The method also comprises determining, by the controller, that a fault has occurred in the power supply system based on the first signal and further based on the second signal.The method further includes controlling, by the controller, the second solid-state power converter in response to determining that the fault has occurred.

[0102] Example 3. The method of Example 1 or Example 2, further comprising determining that an amplitude of the second signal is greater than a first threshold level.

[0103] Example 4. The method of the preceding examples or any combination thereof, further comprising determining that an amplitude of the first signal is less than a second threshold level.

[0104] Example 5. The method of the preceding examples or any combination thereof, further comprising disabling the bus-side switches of the first solid-state power converter in response to determining that the amplitude of the second signal is greater than the first threshold level.

[0105] Example 6. The method of the preceding examples or any combination thereof, further comprising disabling the bus-side switches of the first solid-state power converter in response to determining that the amplitude of the first signal is less than the second threshold level and in response to determining that the amplitude of the second signal is greater than the first threshold level.

[0106] Example 7. The method of the preceding examples or any combination thereof, further comprising disabling the load-side switches of the second solid-state power converter in response to determining that the amplitude of the second signal is greater than the first threshold level.

[0107] Example 8. The method of the preceding examples or any combination thereof, further comprising disabling the load-side switches of the second solid-state power converter in response to determining that the amplitude of the first signal is less than the second threshold level and in response to determining that the amplitude of the second signal is greater than the first threshold level.

[0108] Example 9. The method of the preceding examples or any combination thereof, further comprising determining that an amplitude of the first signal is greater than a first threshold level.

[0109] Example 10. The method of the preceding examples or any combination thereof, further comprising determining that an amplitude of the second signal is less than a second threshold level.

[0110] Example 11. The method of the preceding examples or any combination thereof, further comprising disabling the source-side switches of the first solid-state power converter in response to determining that the amplitude of the first signal is greater than the first threshold level.

[0111] Example 12. The method of the preceding examples or any combination thereof, further comprising disabling the source-side switches of the first solid-state power converter in response to determining that the amplitude of the first signal is greater than the first threshold level and in response to determining that the amplitude of the second signal is less than the second threshold level.

[0112] Example 13. The method of the preceding examples or any combination thereof, further comprising disabling the bus-side switches of the first solid-state power converter in response to determining that the amplitude of the first signal is greater than the first threshold level.

[0113] Example 14. The method of the preceding examples or any combination thereof, further comprising disabling the bus-side switches of the second solid-state power converter in response to determining that the amplitude of the first signal is greater than the first threshold level and in response to determining that the amplitude of the second signal is less than the second threshold level.

[0114] Example 15. The method of the preceding examples or any combination thereof, where the first and second threshold levels are the same threshold level.

[0115] Example 16. The method of the preceding examples or any combination thereof, where the first threshold level is different from the second threshold level.

[0116] Example 17. The method of the preceding examples or any combination thereof, further comprising determining estimated values ​​of the inductances in the power supply system based on the first signal and the second signal.

[0117] Example 18. The method of the preceding examples or any combination thereof, further comprising determining a desired capacitance for an intermediate capacitor of the first solid-state power converter based on the estimated values ​​of the inductances.

[0118] Example 19. The method of the preceding examples or any combination thereof, further comprising controlling a network of switches based on the desired capacitance to adjust an actual capacitance of the intermediate capacitor.

[0119] Example 20. A method includes determining estimated values ​​of inductances in a power supply system based on detected signals, determining a desired capacitance for an intermediate capacitor of a solid-state power converter in the power supply system based on the estimated values ​​of inductances, and controlling a switch network of the solid-state power converter based on the desired capacitance to adjust an actual capacitance of the intermediate capacitor.

[0120] Example 21. The method of the preceding examples or any combination thereof, wherein the determination of the desired capacitance is based on the estimated values ​​of the inductances, is based on a voltage generated by the power source, and / or a threshold current for the solid-state power converter.

[0121] Example 22. The method of the preceding examples or any combination thereof, further comprising adjusting the actual capacitance of the intermediate capacitor by at least connecting or disconnecting capacitors in parallel.

[0122] Example 23. The method of the preceding examples or any combination thereof, wherein a capacitance of the intermediate capacitor is selected based on a threshold level for a current on the load side of the second solid-state power converter, a voltage level delivered by a power source, and / or one or more inductances in the power supply system.

[0123] Example 24. The method of the preceding examples or any combination thereof, wherein a capacitance of the intermediate capacitor is selected based on a formula in which the capacitance of the intermediate capacitor is proportional to a square of the threshold level for the load-side current of the second solid-state power converter and / or one or more inductors in the power supply system.

[0124] Example 25. A system includes a solid-state power converter and a controller configured to perform the method of the preceding examples or any combination thereof.

[0125] Example 26. A system includes a first solid-state power converter including a first set of switches connected to a source side of the first solid-state power converter, a second set of switches connected to a bus side of the first solid-state power converter, and a first intermediate capacitor connected between the first set of switches and the second set of switches. The system also includes a second solid-state power converter including a third set of switches connected to a bus side of the second solid-state power converter, a fourth set of switches connected to a load side of the second solid-state power converter, a second intermediate capacitor connected between the third set of switches and the fourth set of switches.The system further includes a power source connected to the source side of the first solid-state power converter. The system includes a bus connected to the bus side of the first solid-state power converter and to the bus side of the second solid-state power converter. The system also includes a load connected to the load side of the second solid-state power converter.

[0126] Example 27. A device includes a computer-readable medium having stored thereon executable instructions configured to be executable by processing circuitry to cause the processing circuitry to perform the method of Examples 1-24 or any combination thereof.

[0127] Example 28. A system comprising means for carrying out each of the method steps of Examples 1-24 or any combination thereof.

[0128] Various examples have been described. Any combination of the described systems, operations, or functions is conceivable. These and other examples are within the scope of the following claims.

Claims

1. Claims System (100, 200) comprising: a first semiconductor power converter (220A) comprising: a first set of switches (231A, 232A) connected to a source side of the first semiconductor power converter; a second set of switches (233A, 234A) connected to a bus side of the first solid-state power converter; And a first intermediate capacitor (240A) connected between the first set of switches and the second set of switches; a second semiconductor power converter (220B) comprising: a third set of switches (23 IB, 232B) connected to a bus side of the second semiconductor power converter; a fourth set of switches (233B, 234B) connected to a load side of the second semiconductor power converter; and a second intermediate capacitor (240B) connected between the third set of switches and the fourth set of switches; a power source (210) connected to the source side of the first semiconductor power converter; a bus (260) connected to the bus side of the first solid-state power converter and to the bus side of the second solid-state power converter; and a load (270) connected to the load side of the second semiconductor power converter, the system further comprising a first controller comprising processing circuitry, wherein the first controller is configured to: receiving a first signal indicating a current from the source side of the first solid-state power converter; receiving a second signal indicating a current on the bus side of the first solid-state power converter; and controlling the first solid-state power converter, wherein the processing circuitry of the first controller is configured to: determine that a fault has occurred in the electrical power system based on the first signal and further based on the second signal; and causing the first controller to deactivate at least one switch of the first solid-state power converter in response to determining that the fault has occurred.

2. The system of claim 1, wherein a capacitance of the second intermediate capacitor is selected based on a threshold level for a current in the second semiconductor power converter, a voltage level output from the power source, a first inductance on the bus side of the second semiconductor power converter, and a second inductance on the load side of the second semiconductor power converter.

3. The system of claim 2, wherein the capacitance of the second intermediate capacitor is selected based on a formula in which the capacitance of the second intermediate capacitor is proportional to: a square of the threshold level for the current on the load side of the second semiconductor power converter; and the first inductance on the bus side of the second semiconductor power converter.

4. The system of one of the preceding claims, wherein the processing circuitry is configured to: determine that an amplitude of the second signal is greater than a threshold level; and cause the first controller to deactivate the second set of switches in response to determining that the amplitude of the second signal is greater than the threshold level.

5. The system of claim 4, wherein the threshold level is a first threshold level, and wherein the processing circuitry is configured to: determining that an amplitude of the first signal is less than a second threshold level; and causing the first controller to deactivate the second set of switches in response to determining that the amplitude of the first signal is less than the second threshold level and in response to determining that the amplitude of the second signal is greater than the first threshold level.

6. The system of one of the preceding claims, wherein the processing circuitry is configured to: determine that an amplitude of the first signal is greater than a threshold level; and cause the first controller to deactivate the first set of switches in response to determining that the amplitude of the first signal is greater than the threshold level.

7. The system of claim 6, wherein the threshold level is a first threshold level, and wherein the processing circuitry is configured to: determine that an amplitude of the second signal is less than a second threshold level; and cause the first controller to deactivate the first set of switches in response to determining that the amplitude of the first signal is greater than the first threshold level and in response to determining that the amplitude of the second signal is less than the second threshold level.

8. The system of one of the preceding claims, wherein the first intermediate capacitor comprises a network of switchable capacitors, wherein the first solid-state power converter further comprises a network of switches configured to connect and disconnect the network of switchable capacitors to the first and second sets of switches, and wherein the processing circuitry is configured to: determine estimated values ​​of the inductances in the power supply system based on the first signal and the second signal; determine a desired capacitance for the first intermediate capacitor based on the estimated values ​​of the inductances; and control the switch network based on the desired capacitance to adjust an actual capacitance of the intermediate capacitor.

9. The system of one of claims 1 to 3, further comprising a second controller comprising processing circuitry, wherein the second controller is configured to: receive a first signal indicative of a current on the bus side of the second solid-state power converter; receive a second signal indicative of a current on the load side of the second solid-state power converter; and control the second solid-state power converter, wherein the processing circuitry of the second controller is configured to: determine that a fault has occurred in the power supply system based on the first signal and further based on the second signal; and cause the second controller to turn off at least one switch of the second solid-state power converter in response to determining that the fault has occurred.

10. The system of claim 9, wherein the processing circuitry of the second controller is configured to: determine that an amplitude of the second signal is greater than a first threshold level; determine that an amplitude of the first signal is less than a second threshold level; and cause the second controller to deactivate the fourth set of switches in response to determining that the amplitude of the first signal is less than the second threshold level and in response to determining that the amplitude of the second signal is greater than the first threshold level.

11. The system of claim 9, wherein the processing circuitry of the second controller is configured to: determine that an amplitude of the first signal is greater than a first threshold level; determine that an amplitude of the second signal is less than a second threshold level; and cause the second controller to deactivate the third set of switches in response to determining that the amplitude of the second signal is less than the second threshold level and in response to determining that the amplitude of the first signal is greater than the first threshold level.

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