Solid state power controller and aircraft

Abstract

A solid state power controller (SSPC) and an aircraft are provided. The SSPC includes a power supply line configured to be connected between a power source and a load. Further, the solid state power controller includes a semiconductor switching unit disposed on the power supply line and configured to switch between at least two states according to a command signal. The at least two states include a conducting state and a non-conducting state. Further, the solid state power controller includes a state machine configured to assume at least two states including a turn-on state and a turn-off state. The state machine is further configured to output the command signal according to a current state of the state machine.

Description

[0001] This application is a divisional application of the invention patent application filed on February 18, 2022, with application number 202210149885.6 and title "Solid-State Power Controller and Aircraft". Technical Field

[0002] This invention relates to solid-state power controllers and aircraft. Background Technology

[0003] In recent years, electricity has become increasingly important as a form of energy for powering air vehicles. This includes, in particular, electric aircraft with vertical takeoff and landing (eVTOL) capabilities.

[0004] A key component of electric (i.e., electric drive / electric propulsion) aircraft, including eVTOL, is a suitable power controller that controls the power supplied from the power source to a load such as a propulsion unit or multiple propulsion units (especially electric propulsion units (EPUs)).

[0005] Generally, a power controller is a device that controls the power (voltage and / or current) supplied to a load. Power controllers perform monitoring and diagnostic functions to identify overload conditions, detect short circuits, and interrupt power flow. In this regard, it is desirable to interrupt power flow as quickly as possible in the event of a short circuit to limit potential damage. Furthermore, power controllers can limit current during the startup of capacitive loads, protect loads and wiring from overcurrent, and disconnect loads for maintenance purposes.

[0006] Current solutions for achieving these functions involve a series connection of electromechanical switches (contaminants) and overcurrent protection systems such as thermal fuses. This solution is characterized by high mechanical complexity, high quality, and low efficiency. Furthermore, such solutions are susceptible to aging effects due to moving parts, contact corrosion due to electric arcing, and / or fatigue due to thermomechanical stress. Therefore, close monitoring and potentially lifetime maintenance are required.

[0007] Traditional solid-state power controllers (SSPCs) are semiconductor devices that function similarly to electronic circuit breakers in protecting loads from dangerous faults, but are more reliable and faster during power outages. SSPCs include a programmable microprocessor, enabling control via a digital bus and flexible adjustment of current / time characteristics. Current solutions involving solid-state power controller systems rely on complex electronics to implement safety-critical functions such as overcurrent protection, requiring redundancy and heterogeneity.

[0008] As with air traffic in general, the highest safety standards apply to aircraft components, including power controllers, power sources, and power units (EPUs) such as SSPCs. However, due to the complexity of traditional SSPCs, these SSPCs may be subject to a number of failure conditions, including but not limited to software vulnerabilities, hidden design or manufacturing defects, or faulty maintenance.

[0009] To ensure safe operation during flight and on the ground, SSPC malfunctions within the aircraft should be detected and addressed in a manner that maximizes safety, while maintaining the aircraft’s primary functions (i.e., maintaining a safe state of being during flight) as much as possible.

[0010] Therefore, during the design of power controllers, especially for applications within aircraft, a key task is to minimize the risk of failure of any components that are highly reliable and require less maintenance. Summary of the Invention

[0011] The purpose of this invention is to provide a power controller that exhibits high reliability, low failure risk, low maintenance requirements and low aging effect.

[0012] This is achieved through the features of the independent claims. The dependent claims describe advantageous embodiments.

[0013] According to a first aspect, a solid-state power controller (SSPC) is provided. The SSPC includes a power supply line configured to connect between a power source and a load. Furthermore, the SSPC includes a semiconductor switching unit disposed on the power supply line and configured to switch between at least two states according to a command signal. The at least two states include an ON state and a OFF state. Additionally, the SSPC includes a state machine configured to present at least two states, including an ON state and an OFF state. The state machine is also configured to output a command signal based on its current state.

[0014] In other words, the SSPC is configured to be positioned on the power supply line connecting the power source and the load. The state machine presents at least two states, based on which command signals are used to control the semiconductor switching unit. Specifically, if the semiconductor switching unit operates in the ON state, it electrically connects the power source and the load. Conversely, if the semiconductor switching unit operates in the OFF state, it disconnects the electrical connection between the power source and the load. The state machine presents at least two states (i.e., ON and OFF) and allows transitions between these states.

[0015] The state of a semiconductor switching unit can be referred to as a switching state to distinguish it from the state of a state machine.

[0016] The conducting state of the semiconductor switching unit can be a state where the resistance through the semiconductor switching unit is lower than a first threshold. The non-conducting state can be a state where the resistance through the semiconductor switching unit is higher than a second threshold.

[0017] Note that the number of states in a state machine is not limited to two; it can be three, four, or more than four. Generally, a state machine can present multiple states, including an on state and an off state. The semiconductor switching unit is controlled by a command signal, which is output by the state machine based on its current state. The command signal can indicate the state to which the semiconductor switching unit should transition, or cause the semiconductor switching unit to enter an on or off state based on the command signal.

[0018] According to ARP4754A: “Guidelines for Development of Civil Aircraft and Systems”, December 2010, https: / / www.sae.org / standards / content / arp4754a / , the SSPC configuration allows for certification as electronic hardware.

[0019] Additionally or optionally, according to “RTCA DO-254 / EUROCAE ED-80, Design Assurance Guidance for Airborne Electronic Hardware” dated April 19, 2000, from RTCA, Inc., http: / / www.rtca.org / , the SSPC configuration may allow certification as “simple hardware”.

[0020] Furthermore, the present invention can achieve lower equipment weight and thus increased payload, fewer maintenance cycles and reduced certification work during the development process, and thus faster progress to service.

[0021] According to an embodiment, the state machine is a non-programmable logic unit composed of multiple non-programmable electronic components. The semiconductor switching unit is composed of one or more non-programmable electronic components.

[0022] A non-programmable electronic component is an electronic component whose characteristics and behavior within an electrical circuit are determined solely by its hardware configuration. In other words, the characteristics and behavior of a non-programmable electronic component cannot be defined by software or firmware.

[0023] Non-programmable electronic components include amplifiers, comparators and other analog components such as multipliers, current sensors, voltage sensors, temperature sensors, and isolated signal components such as digital isolators, isolation amplifiers, or optocouplers. Furthermore, non-programmable electronic components include linear and switching voltage regulators, oscillators, logic gates, buffers, flip-flops, registers and latches, as well as analog-to-digital converters and voltage references. The examples described are not exhaustive.

[0024] A state machine can be constructed from non-programmable components, and therefore can be a hardware device for which a comprehensive combination of deterministic testing and analysis, suitable for a specific development assurance level, can ensure correct functional performance under all foreseeable operating conditions without abnormal behavior. Logic components can also be referred to as logic circuits.

[0025] SSPC provides power control with a safe-state ON capability when communication, sensing, or monitoring is lost. SSPC can provide overcurrent protection based on simple current sensing and non-programmable components for current-time characteristics.

[0026] Using non-programmable electronics to enable safe states, while reserving complex / programmable electronics solely for monitoring and communication functions, allows for deterministic behavior of critical system components, thereby simplifying testing and certification.

[0027] In this embodiment, if the current state of the state machine is off, the command signal indicates that the semiconductor switching unit should be in a non-conducting state. Conversely, if the current state of the state machine is on, the command signal indicates that the semiconductor switching unit should be in a conducting state.

[0028] In other words, the semiconductor switching unit is controlled to electrically connect the power source and the load when the current state of the state machine is ON, and to electrically disconnect the connection between the power source and the load when the current state of the state machine is OFF.

[0029] In one embodiment, the solid-state power controller includes a current sensor disposed on the power supply line and configured to detect current. Furthermore, the solid-state power controller includes an overcurrent detection unit configured to detect overcurrent using the current detected by the current sensor. A state machine is configured to change its current state based on the detection result of the overcurrent detection unit.

[0030] In other words, the current sensor measures the current flowing through the power supply line and provides the measurement signal to the overcurrent detection unit. The overcurrent detection unit determines whether an overcurrent condition is met. Based on the determination result, the state machine can change its current state. For example, the state machine can be configured to transition to an off state if the overcurrent detection unit detects an overcurrent. For example, if an overcurrent is detected, the state machine can transition from an on state or another state to an off state. If the current state of the state machine is off and the overcurrent detection unit detects an overcurrent, the state machine can maintain its current state, i.e., the off state.

[0031] In one embodiment, the solid-state power controller includes: a current sensor disposed on the power supply line and configured to detect current; and an overcurrent detection unit configured to detect overcurrent using the current detected by the current sensor. A state machine may be configured to transition to an off state upon detection of overcurrent by the overcurrent detection unit.

[0032] For example, an overcurrent detection unit is configured to detect overcurrent by integrating the square of the detected current over a predetermined time period and comparing the integration result with an integration threshold.

[0033] In other words, the overcurrent detection unit can simulate the behavior of a fuse exhibiting a specific I²t characteristic. The I²t rating is related to the amount of energy channeled through the corresponding electrical component. The overcurrent detection unit can be configured to determine the presence of an overcurrent flowing through the power supply line if the integral result is higher than an integral threshold.

[0034] According to one embodiment, the solid-state power controller further includes a temperature sensor configured to detect the temperature of the solid-state power controller and output a temperature signal representing the detected temperature to a state machine. The state machine can be configured to change its current state based on the temperature signal.

[0035] In other words, the state machine can use the temperature measurement signal output by the temperature sensor to change its current state. For example, the measurement signal can be compared with a temperature threshold. If the temperature is higher than the temperature threshold, the state machine can be configured to transition to an off state. If the current state is off and the temperature is higher than the temperature threshold, the state machine can be configured to maintain the current state, i.e., the off state.

[0036] Temperature sensors can be placed in any suitable location. For example, a temperature sensor can measure the temperature of a specific component in an SSPC, such as a semiconductor switching unit.

[0037] In one embodiment, the solid-state power controller includes a temperature sensor configured to detect the temperature of the solid-state power controller and output a temperature signal representing the detected temperature to a state machine, wherein the state machine is configured to transition to an off state if the temperature represented by the temperature signal is higher than a temperature threshold.

[0038] According to one embodiment, the solid-state power controller further includes a voltage sensor configured to detect the voltage downstream of the semiconductor switching unit and output a voltage signal representing the detected voltage to a state machine. The state machine can be configured to change its current state based on the voltage signal.

[0039] In other words, a state machine can use a voltage measurement signal output by a voltage sensor to change its current state. For example, the measurement signal can be compared with a voltage threshold. If the voltage is higher than the voltage threshold, the state machine can be configured to transition to an off state. If the current state is off and the voltage is higher than the voltage threshold, the state machine can be configured to maintain the current state, i.e., the off state.

[0040] Voltage sensors can be placed in any suitable location. For example, a voltage sensor can be provided to measure the voltage across a semiconductor switching unit.

[0041] In one embodiment, the solid-state power controller includes a voltage sensor configured to detect the voltage of a power supply line downstream of a semiconductor switching unit and output a voltage signal representing the detected voltage to a state machine, wherein the state machine is configured to transition to an off state if the voltage represented by the voltage signal is higher than a voltage threshold.

[0042] In this embodiment, the state of the semiconductor switching unit also includes an intermediate state, wherein the semiconductor switching unit is configured to limit the current on the power supply line to below a predetermined current threshold according to a command signal. If the current state of the state machine is a pre-charge state, the command signal indicates that the semiconductor switching unit should be in the intermediate state.

[0043] In other words, the state machine's states include an on state, a non-on state, and an intermediate state, which allows specific current to flow through the power supply line and thus through the semiconductor switching unit. Furthermore, in addition to the on and off states, the state machine also exhibits at least a pre-charge state. In the pre-charge state, the state machine outputs a command signal to the semiconductor switching unit, thereby limiting the current flowing through the semiconductor switching unit.

[0044] For example, when the voltage across the semiconductor switching unit is lower than the pre-charge voltage, and / or when the current through the semiconductor switching unit is lower than the pre-charge current threshold, the state machine can be configured to transition from the pre-charge state to the on state.

[0045] In one embodiment, the semiconductor switching unit limits the current on the power supply line by exhibiting resistance according to a command signal.

[0046] In other words, the intermediate state can be the state in which the semiconductor switching unit exhibits resistance between the first and second thresholds mentioned above. The current flowing through the power supply line (and therefore through the SSPC, particularly the semiconductor switching element) is limited by the resistance exhibited by the switching unit.

[0047] In an embodiment, the intermediate state is the state in which the semiconductor switching unit alternates between an on state and an off state, thereby limiting the average current flowing through the semiconductor switching unit over time.

[0048] According to an embodiment, the semiconductor switching unit is a metal-oxide-semiconductor field-effect transistor, i.e., a MOSFET. The source and drain terminals of the MOSFET can be connected to a power supply line. The gate terminal of the MOSFET can be connected to a state machine.

[0049] For example, the MOSFET is a p-type or n-type enhancement MOSFET.

[0050] For example, a state machine can be configured to output a command signal to the gate terminal of a MOSFET.

[0051] In one embodiment, the solid-state power controller further includes a circuitry connected to the state machine. This circuitry is configured to monitor the state of the state machine, the current detected by a current sensor, the state of the semiconductor switching unit, the temperature detected by a temperature sensor, and / or the voltage detected by a voltage sensor. Furthermore, the circuitry can be configured to output a vehicle command signal to the state machine. The vehicle command signal can indicate the state to which the state machine should transition.

[0052] In other words, the SSPC includes a circuit system that monitors readings from dedicated sensors such as voltage, current, or temperature sensors. Furthermore, this circuit system can monitor the current state of the state machine and / or the state of the semiconductor switching units. For this purpose, the circuit system can be connected to the individual sensors and / or components (state machine, semiconductor switching units, etc.).

[0053] In an embodiment, the circuit system may be configured to be connected to an external communication line and configured to communicate via the external communication line.

[0054] In other words, the semiconductor switching unit can be connected to an external communication line such as a bus and communicate with one or more external devices. For example, the circuit system can communicate with a flight control system (FCS) and receive command signals and send report signals. For example, the circuit system can receive command signals from an external FCS and output vehicle command signals to the state machine based on the received command signals.

[0055] According to a second aspect, an aircraft is provided. The aircraft includes a solid-state power controller, a power source, and a load according to any one of the first aspect or embodiments thereof.

[0056] An aircraft can be a vehicle capable of flying by using static or dynamic lift to gain support from the air. An aircraft can be any type of aircraft, including but not limited to fixed-wing aircraft such as airplanes or rotary-wing aircraft such as helicopters. The load can be a propulsion unit, particularly an electric propulsion unit such as an electric fan, thruster, or ducted fan.

[0057] Preferably, the aircraft is an electric vertical takeoff and landing (eVTOL) aircraft. Attached Figure Description

[0058] As shown in the accompanying drawings, additional features and advantages of the invention will become apparent in the following more detailed description, wherein:

[0059] Figure 1 This is a schematic structural diagram of a solid-state power controller according to an embodiment;

[0060] Figure 2 This is a schematic diagram illustrating an implementation example of a solid-state power controller according to an embodiment;

[0061] Figure 3 This is another schematic diagram illustrating an implementation example of the solid-state power controller according to the first embodiment;

[0062] Figure 4 This is another schematic diagram illustrating an implementation example of the solid-state power controller according to the first embodiment;

[0063] Figure 5 This is another schematic diagram illustrating an implementation example of the solid-state power controller according to the first embodiment;

[0064] Figure 6 An example of implementing an overcurrent detection device is shown;

[0065] Figure 7 This is a schematic diagram of an aircraft according to an embodiment. Detailed Implementation

[0066] This invention relates to a solid-state power controller (SSPC), which can be used, for example, in electrically powered aircraft. The SSPC includes a state machine and semiconductor switching units, which can connect or disconnect the electrical connection of the power supply line according to the state of the state machine via the semiconductor switching units.

[0067] Figure 1 This is a schematic structural diagram of an SSPC according to an embodiment. SSPC 100 includes a power supply line 110 configured to connect to a power source 200 and a load 300. A semiconductor switching unit 120 is disposed on the power supply line 110. Furthermore, a current sensor 140 is disposed on the power supply line 110 and configured to measure the current flowing through the power supply line 110. Additionally, SSPC 100 includes a voltage sensor that measures the voltage on the power supply line 110 (e.g., downstream of the semiconductor switching unit 120). The voltage sensor may (additionally or alternatively) measure the voltage across a MOSFET 120. Furthermore, SSPC 100 includes an overcurrent detection unit 150, a temperature sensor 160, a voltage sensor 170, and a state machine 130. SSPC 100 may further include a circuit system 180 that can communicate via an external communication line such as a bus.

[0068] As further defined above, the components within the dashed section of the SSPC can consist of multiple non-programmable electronic components. The circuit system can be programmable and can be, for example, a microcontroller or microprocessor.

[0069] Semiconductor switching unit 120 is an enhancement-mode metal-oxide-semiconductor field-effect transistor (MOSFET), with its drain and source terminals connected to power supply line 110. The gate terminal of MOSFET 120 is connected to state machine 130. Based on a command signal provided by state machine 130 and input to the gate terminal of MOSFET 120, MOSFET 120 presents an on-state, intermediate-state, and off-state. MOSFET 120 can operate in an on-state, off-state, or intermediate-state depending on the voltage applied to its gate terminal. In the intermediate-state, MOSFET 120 can operate in its linear state.

[0070] Voltage sensor 170 senses the voltage on power supply line 110 (e.g., downstream of MOSFET 120). However, voltage sensor 170 can be configured to measure the voltage drop across an electronic component such as MOSFET 120. Voltage sensor 170 outputs a signal representing the detected voltage to state machine 130 and circuit system 180.

[0071] A current sensor 140 is disposed on the power supply line 110 and outputs a current signal representing the current flowing through the power supply line 110 to the overcurrent detection unit 150 and the circuit system 180.

[0072] Overcurrent detection unit 150 is configured to determine whether an overcurrent has occurred on power supply line 110. Overcurrent detection unit 150 can be a simple comparator configured to compare the current signal output by current sensor 140 with a reference signal, and determine that an overcurrent exists if the current signal is higher than the reference signal. Alternatively, overcurrent detection unit 150 can integrate the square of the current signal over a predetermined time period and compare the integration result with a (different) reference signal. If the integration result is higher than the reference signal, an overcurrent can be determined to have occurred. Overcurrent detection unit 150 is configured to output an overcurrent signal to a state machine indicating whether an overcurrent has been detected. The following reference... Figure 6 This section explains the specific implementation of the overcurrent detection unit 150.

[0073] Temperature sensor 160 is configured to measure the temperature of SSPC 100 and output the corresponding temperature signal to state machine 130 and circuit system 180.

[0074] The circuit system 180 is connected to the state machine 130, various temperature sensors 160, an overcurrent detection unit 150, a current sensor 140, a voltage sensor 170, a MOSFET 120, and / or an external communication line. The circuit system 180 is configured to monitor sensor readings and the states of the state machine 130 and the MOSFET 120. For example, the circuit system 180 can transmit messages indicating any monitored values ​​via the external communication line. Furthermore, the circuit system 180 can receive command messages, for example, from a flight control system (FCS) via the external communication line and output vehicle commands indicating the state to which the state machine 130 should transition to to the state machine 130.

[0075] State machine 130 is connected to temperature sensor 160, overcurrent detection unit 150, voltage sensor 170, semiconductor switching unit 120, and circuit system 180. The state machine exhibits three states: ON, OFF, and pre-charge. The current state of state machine 130 is determined by the reading of voltage sensor 170, the input signal of overcurrent detection unit 150, the temperature signal provided by temperature sensor 160, and vehicle commands that can be input from circuit system 180. State machine 130 is configured to control MOSFET 120 to operate in an ON, intermediate, or OFF state based on its current state.

[0076] In the ON state, MOSFET 120 is controlled to be in the ON state, thereby allowing current to flow through power supply line 110. In the OFF state, MOSFET 120 is controlled to be in the OFF state, thereby preventing current from flowing through power supply line 110. In the precharge state, MOSFET 120 is controlled to limit the current flowing through power supply line 110. For example, when the state machine is in the precharge state, MOSFET 120 operates in its linear state. When the load exhibits a large capacitance, it may be necessary to limit the current flowing through power supply line 110, thereby causing an initial large current (inrush current) through power supply line 110.

[0077] State machine 130 enables transitions between an ON state, an OFF state, and a pre-charge state. Specifically, state machine 130 can transition from an OFF state to a pre-charge state and vice versa. Furthermore, the state machine can transition from a pre-charge state to an ON state and from an ON state to an OFF state. Each transition is determined by various inputs to state machine 130.

[0078] For example, if a vehicle command indicating a transition from state machine 130 to pre-charge is input to state machine 130, which is currently in an off state, then state machine 130 transitions from the off state to the pre-charge state. If overcurrent is detected by overcurrent detection unit 150, state machine 130 transitions from the pre-charge state or from the on state to the off state. This can also be applied if the temperature detected by temperature sensor 160 is above a certain temperature threshold, and / or if the voltage detected by voltage sensor 170 is above a voltage threshold. If the current state of state machine 130 is pre-charge, state machine 130 can transition to the on state if the voltage across MOSFET 120 (i.e., across the drain and source terminals) drops below a pre-charge voltage threshold, or if the current through MOSFET 120 is below a pre-charge current threshold. For measuring voltage drop, SSPC 100 may include a dedicated voltage sensor.

[0079] Specifically, state machine 130 and other components (other than circuit system 180) can be composed of multiple non-programmable electronic components. The specific implementation is described below.

[0080] Figure 2 This is a schematic diagram illustrating an implementation example of a solid-state power controller 100 according to an embodiment. The state machine 130, represented by the dashed rectangle, is a non-programmable logic component that includes an OR gate 1, a latch 2 (flip-flop), a CMOS inverter 3, a gate drive amplifier 4, and a multiplier 5. Furthermore, the SSPC 100 includes a current sensor 140, a voltage sensor 170, and a power supply line 110.

[0081] An overcurrent (OC) signal and an overtemperature (OT) signal are input to an OR gate. The OC signal can be provided by the overcurrent detection unit 150 and can represent an overcurrent condition as a logic true (high value) and the absence of overcurrent as a logic false (low value / zero). The signal provided by the temperature sensor 160 can be input to a comparator, which provides the OT temperature by comparing it with a reference signal using the signal provided by the temperature sensor 160. The OT signal can represent a logic true under an overtemperature condition. If one or both of the OC and OT signals are true, the output signal of OR gate 1 is true.

[0082] The output of OR gate 1 is input to the set input (S) of latch 2. The FCS:Reset signal can be input to the reset input (R) of latch 2 by circuitry 180 (based on commands received from the flight control system (FCS) via an external communication line). The latch's non-inverting output Q is connected to the input of CMOS inverter 3. Therefore, if an OC and / or OT occurs (and latch 2 is not reset by the FCS), a true signal will be output to CMOS inverter 3, and if neither OC nor OT occurs, a false signal will be input to CMOS inverter 3.

[0083] Based on the CMOS inverter input signal, the reference voltage Vref or zero is input to the non-inverting input of the gate drive amplifier 4. Multiplier 5 calculates the power dissipated in MOSFET 120 based on the voltage measured across MOSFET 120 by voltage sensor 170 and the current flowing through MOSFET 120 measured by current sensor 140. The output signal of the multiplier, proportional to the power dissipation within MOSFET 120, is input to the inverting terminal of the gate drive amplifier.

[0084] Gate driver amplifier 4 amplifies the difference between the output of CMOS inverter 3 and multiplier 5, and outputs the amplified signal to the gate electrode of MOSFET 120. The output signal of gate driver amplifier 4 minimizes the difference between the input signals. Therefore, when the output of CMOS inverter 3 is zero (i.e., OC and / or OT occur), the power dissipation in MOSFET 120 is minimized. If no OT or OC occurs, a reference voltage Vref is applied to the inverting input of gate driver amplifier 4. The reference voltage Vref is a predetermined voltage and corresponds to the maximum power dissipation of MOSFET 120 to limit the current through power supply line 110. For example, the reference voltage can be set to a voltage corresponding to a specific power dissipation of 160W.

[0085] Therefore, according to the implementation example, state machine 130 presents an off state as the current state when an error occurs, and a combined pre-charge and on state when no fault occurs (OC, OT). In the pre-charge / on state, the maximum power dissipation in MOSFET 120 is determined by the reference voltage Vref. That is, in the pre-charge / on state, the power dissipation in MOSFET 120 is limited, thus preventing possible inrush current.

[0086] Figure 3 This is a schematic diagram illustrating an implementation example of a solid-state power controller according to another embodiment. Figure 3 The SSPC shown is as follows Figure 2 The components of the SSPC shown are denoted by the same reference numerals, and the descriptions given above also apply.

[0087] Figure 3 The SSPC 100 shown is... Figure 2 The difference in the SSPC 100 shown is the second latch 6, the second OR gate 7, the comparator 8, the third latch 9, and the second CMOS inverter 10.

[0088] The vehicle command FCS:Arm can be input to the S input of the second latch 6. This vehicle command can be input by circuitry 180 (not shown) based on a command sent from the FCS via an external communication line. As will be shown below, state machine 130 remains in the off state until it is receiving the FCS:Arm vehicle command. The inverted output of the second latch 6 is connected to the input of the second OR gate 7. Furthermore, the output of the (first) latch 2 is input to another input of the second OR gate 7. That is, if an OC / OT occurs, and / or the FCS:Arm command has not yet been input to the second latch 6, the output of the second OR gate 7 is a true signal. In other words, if an OT / OC occurs, or state machine 130 is not instructed to enter the pre-charge state by the FCS:Arm command, the input to the non-inverting terminal of the gate drive amplifier 4 is zero.

[0089] When the FCS:Arm command is input to the second latch 6 and no OT / OC occurs, the output of CMOS inverter 3 is equal to the output of the second CMOS inverter 10. Therefore, based on the input to the second CMOS inverter, the power dissipation within MOSFET 120 is controlled to correspond to the voltage output by the second CMOS inverter (which is either the reference voltage Vref or the positive supply power voltage). The input to the second CMOS inverter depends on whether the voltage across MOSFET 120 drops below a voltage threshold Vth. Vth is a predetermined threshold voltage input to the non-inverting input of comparator 8. The voltage Vds across MOSFET 120 (e.g., via a low-pass filter) is input to the inverting input of comparator 8. If Vds is greater than Vth, a true signal is input to the third latch 9, thereby causing a false signal to be input to the second CMOS inverter 10, applying Vref to the gate drive amplifier 4. If Vdc drops below Vth, positive supply power is input to the gate drive amplifier 4.

[0090] In summary, according to the embodiment, the SSPC is in an off state when it does not receive FCS:Arm and / or when OT / OC occurs, wherein the power dissipation in MOSFET 120 is controlled to zero. Furthermore, the SSPC 100 is in a pre-charge state when Vds is higher than Vth and FCS:Arm is received, wherein the power dissipation in MOSFET 120 is controlled according to the reference voltage Vth. Once Vds drops below Vth, the SSPC 100 immediately enters an on state, wherein the power dissipation in MOSFET 120 is controlled according to the positive supply power voltage.

[0091] In other words, MOSFET 120 is controlled to be in the ON state when the current state is ON, in the OFF state when the current state is OFF, and in an intermediate state when SSPC 100 is in the pre-charge state, wherein the power dissipation within MOSFET 120 is controlled to not exceed a threshold. Specifically, in the event of OC / OT, SSPC 100 transitions to the OFF state. Furthermore, although SSPC 100 can be controlled by circuitry 180 (by providing FCS:Arm) to enter the pre-charge state, circuitry 180 cannot cause SSPC 100 to undergo any other transitions.

[0092] Figure 4This is a schematic diagram of an implementation example of a solid-state power controller 100 according to another embodiment. In this embodiment, current is limited in the pre-charge state by using a pulse-width modulation operated MOSFET 120. The state machine 130 includes an OR gate 11, a latch 12, a voltage error amplifier 13, a PWM comparator 14, and a gate drive amplifier 15 with protection features. For example, protection features such as desaturation detection or soft turn-off are generally known for components driving insulated-gate bipolar transistors. Some implementations may utilize Miller clamping or undervoltage lockout (UVLO).

[0093] Reference Figure 2 and Figure 3 As in the aforementioned embodiment, an overcurrent (OC) signal and an overtemperature (OT) signal are input to an OR gate 11, the output of which is input to the S input of latch 12. An FCS:Reset signal can be input to the R input of latch 12. The FCS:Reset signal can be provided by circuitry 180. The inverted output signal of latch 12 is input to the protection input (EN) of gate drive amplifier 15. Gate drive amplifier 15 is configured to output zero when a false signal is input to the protection input (EN).

[0094] To prevent the circuit system 180 from unintentionally resetting the state machine 130 due to a fault that would permanently provide an FCS:Reset command, the output of the circuit system 180 can be prevented from being input to the state machine 130 unless a predetermined amount of time has elapsed since the previous FCS:Reset command. For this purpose, the SSPC 100 may include a timer circuit connected between the circuit system 180 and the state machine 130. The FCS:Reset command can be input to the timer circuit, which is configured to output the FCS:Reset command to the state machine 130 only after a predetermined amount of time has elapsed since the previous FCS:Reset command. The timer circuit can be restarted when it outputs the FCS:Reset command.

[0095] The reference voltage Vref and the voltage Vds measured by the voltage sensor 170 across the MOSFET 120 are input to the voltage error amplifier 13. For example, the reference voltage Vref can be predetermined. The output of the voltage error amplifier 13 (i.e., the amplified difference between Vds and Vref) is input to the inverting input of the PWM comparator 14. A sawtooth voltage signal is input to the non-inverting input of the PWM comparator 14.

[0096] Therefore, the output of PWM comparator 14 is a pulse signal, the duty cycle of which depends on the difference between Vref and Vds. When the amplification difference is equal to or higher than the peak voltage of the sawtooth voltage signal, the comparator outputs zero. When the amplification difference is equal to or lower than the minimum voltage of the sawtooth voltage signal, PWM comparator 14 outputs a constant signal. Furthermore, when the amplification difference is between the minimum and maximum voltages of the sawtooth voltage signal, a pulse signal is output, where the pulse width increases as the amplification difference decreases.

[0097] The output of PWM comparator 14 is input to gate drive amplifier 15, which amplifies the signal and outputs the amplified signal to the gate terminal of MOSFET 120. Therefore, MOSFET 120 is controlled to be in an on or off state based on the value of the signal output by gate drive amplifier 15. Specifically, if Vds is greater than Vref, and the amplification difference between the two is equal to or greater than the maximum value of the sawtooth voltage signal, the MOSFET is controlled to be in an off state. If Vds is equal to or greater than Vref, and the amplification difference between the two is less than the maximum value of the sawtooth voltage signal, MOSFET 120 is controlled in a pulsed manner, causing MOSFET 120 to alternately be in an on or off state. If Vds is less than Vref, MOSFET 120 is controlled to be continuously in an on state.

[0098] Therefore, in summary, the SSPC 100, including the state machine 130 as described above, presents three states (disconnected, connected, pre-charged), wherein the MOSFET is in a conducting state, a non-conducting state, or an intermediate state, and the MOSFET switches between the conducting state and the non-conducting state according to the PWM described above.

[0099] Figure 5 This is a schematic diagram illustrating an implementation example of a solid-state power controller according to another embodiment. Figure 5 The SSPC100 shown is similar to... Figure 4 The components of the SSPC 100 shown are denoted by the same reference numerals, and the descriptions given above also apply.

[0100] The state machine 130 includes a first OR gate 11, a first latch 12, a comparator 16, a second latch 17, a third latch 18, a CMOS inverter 19, a second OR gate 20, and a gate drive amplifier 15 with protection features.

[0101] The voltage Vds across MOSFET 120, measured by voltage sensor 170 (e.g., via a low-pass filter), is input to the inverting input of comparator 16. A predetermined threshold voltage Vth is used as the input to the non-inverting input of comparator 16. The output of comparator 16 is a true signal when Vds is below Vth. Conversely, when Vds is greater than Vth, comparator 16 outputs zero. The output of the comparator (via latch 17) is input to a second OR gate 20.

[0102] The vehicle command FCS:Arm can be input to the S input of the third latch 18, and the vehicle command FCS:Reset can be input to the R input of the third latch. The output signal of the inverting output terminal of the third latch 18 is input to the CMOS inverter 19. Depending on the output signal, the CMOS inverter 19 outputs a zero-OR pulse signal to the second OR gate 20. This pulse signal can be from, as referenced above... Figure 4 The circuit (which includes a voltage error amplifier 13 and a PWM comparator 14) is input to a CMOS inverter 19. The output of the second OR gate is input to a gate drive amplifier 15, which accordingly controls a MOSFET 120.

[0103] Therefore, when an FCS:Arm vehicle command is provided, a pulse signal is input to the second OR gate 20, causing MOSFET 120 to switch between on and off states according to the PWM (intermediate state of MOSFET 120 / pre-charge state of state machine 130). When pre-charge is complete and Vds drops below Vth, the second OR gate 15 outputs a constant signal, causing MOSFET 120 to operate continuously in the on state (on state of state machine 130). If OC and / or OT occurs, or if no FCS:Arm vehicle command signal is provided, MOSFET 120 operates in the off state (off state of state machine 130).

[0104] In summary, Figure 5 The illustrated state machine 130 presents an ON state, an OFF state, and a pre-charge state. In the ON state, MOSFET 120 operates in a ON state. In the OFF state, MOSFET 120 operates in a OFF state. In the pre-charge state, MOSFET 120 operates in an intermediate state, where MOSFET 120 switches between ON and OFF according to a PWM signal. Furthermore, state machine 130 transitions from the OFF state to the pre-charge state upon receiving an FCS:Arm vehicle command. Additionally, upon completion of pre-charge, the state machine transitions to the ON state. Furthermore, in the event of a fault (OT and / or OC), state machine 130 transitions to the OFF state.

[0105] Although a MOSFET 120 is used in the above embodiments, the invention is not limited thereto, and another controllable semiconductor switching unit can be used. For example, a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT), or a junction gate field-effect transistor (JFET) can be used. Furthermore, multiple MOSFETs 120 can be used as semiconductor switching units, wherein the MOSFETs are connected to each other in a parallel configuration.

[0106] Figure 6 An example implementation of an overcurrent detection device is shown below. As described, for example, in Ron Mancini's A.4.9, "OpAmps For Everyone: Design Reference", Texas Instruments, Newnes, Second Edition, April 2003, the overcurrent detection device consists of an analog integrator circuit with a resistor reset. The output of the integrator circuit is proportional to the integral value of the input voltage VIN (over a certain time period).

[0107] As is generally known, specific integral characteristics depend on the characteristics of resistors RG and RF, as well as capacitor C. To simulate the I²t curve of a fuse, for example, several exemplified integrator circuits can be combined in parallel. EP 0 600 751 A2 and US 5 723915 A describe analog circuits for simulating the I²t curve. Furthermore, EP 3 624 339 A1 provides a description of an overcurrent limiting circuit using simple logic elements.

[0108] The input to the overcurrent detection unit can be a voltage signal corresponding to the current supplied by the current sensor 140 through the power supply line 110. The output of the integrator circuit can be input to a comparator configured to compare the output with a predetermined reference voltage and output a signal indicating whether the integral value is higher than the integral threshold.

[0109] Figure 7 This is a schematic diagram of an aircraft according to an embodiment. For example, the aircraft may be an aircraft having a general configuration as described in US 2016 / 0023754 A1. However, the invention is not limited thereto, and the aircraft may be an aircraft having the general configuration of any other conventional aircraft. Figure 7As shown, aircraft 400 includes multiple power sources 200a, 200b, multiple loads 300a-d, and multiple SSPCs 100a-d. In the illustrated configuration, aircraft 400 includes two separate power supply circuits, each including a power source, two SSPCs, and two loads connected to each other. However, the invention is not limited thereto, and aircraft 400 may include any other number of power sources, SSPCs, and loads. Loads 300a-d may be propulsion units, more specifically electric propulsion units such as thrusters or ducted fans. SSPCs may be configured according to any of the embodiments described above.

[0110] This invention is defined by the appended claims and is not limited to the details of the embodiments described in the detailed description above.

[0111] In summary, the present invention relates to a solid-state power controller (SSPC). The SSPC includes a power supply line configured to connect between a power source and a load. Furthermore, the solid-state power controller includes a semiconductor switching unit disposed on the power supply line and configured to switch between at least two states according to a command signal. The at least two states include an on state and a non-on state. Additionally, the solid-state power controller includes a state machine configured to present at least two states, including an on state and an off state. The state machine is also configured to output a command signal based on its current state.

Claims

1. A solid-state power controller, comprising: A power supply line (110) is configured to connect between a power source (200) and a load (300); A semiconductor switching unit (120) is disposed on the power supply line (110) and configured to switch between at least three states, including an on state, a non-on state and an intermediate state, according to a command signal, wherein the semiconductor switching unit is configured to limit the current on the power supply line to below a predetermined current threshold according to the command signal in the intermediate state. State machine (130), which is configured as follows: It presents at least three states, including an on state, an off state, and a pre-charge state; The command signal is output based on the current state of the state machine (130). If the current state of the state machine (130) is the pre-charge state, the command signal indicates that the semiconductor switching unit (120) should be in the intermediate state; and The state machine is configured as follows: Transitions from the disconnected state to the pre-charged state, from the pre-charged state to the disconnected state, from the pre-charged state to the connected state, and from the connected state to the disconnected state are only permitted.

2. The solid-state power controller according to claim 1, wherein, The state machine (130) is a non-programmable logic unit formed by multiple non-programmable electronic components, and The semiconductor switching unit (120) is formed by one or more non-programmable electronic components.

3. The solid-state power controller according to claim 1 or 2, wherein, If the current state of the state machine (130) is the off state, then the command signal indicates that the semiconductor switching unit (120) should be in the non-conducting state, and If the current state of the state machine (130) is the ON state, then the command signal indicates that the semiconductor switch unit (120) should be in the ON state.

4. The solid-state power controller according to claim 1 or 2, further comprising: A current sensor (140) is disposed on the power supply line and configured to detect current; as well as An overcurrent detection unit (150) is configured to detect overcurrent using the current detected by the current sensor (140). The state machine (130) is configured to change the current state based on the detection result of the overcurrent detection unit (150).

5. The solid-state power controller according to claim 4, wherein, The overcurrent detection unit (150) is configured to detect the overcurrent by integrating the square of the detected current over a predetermined time period and comparing the integration result with an integration threshold.

6. The solid-state power controller according to claim 4, further comprising: A temperature sensor (160) is configured to detect the temperature of the solid-state power controller and output a temperature signal representing the detected temperature to the state machine (130). The state machine (130) is configured to change the current state based on the temperature signal.

7. The solid-state power controller according to claim 6, further comprising: A voltage sensor (170) is configured to detect the voltage of the power supply line (110) downstream of the semiconductor switching unit (120) and output a voltage signal representing the detected voltage to the state machine (130). The state machine (130) is configured to change its state based on the voltage signal.

8. The solid-state power controller according to claim 1, wherein, The state machine (130) is configured to transition from the pre-charge state to the on state when the current passing through the semiconductor switching unit (120) is lower than the pre-charge current threshold.

9. The solid-state power controller according to claim 7 or 8, wherein, The semiconductor switching unit (120) limits the current on the power supply line by exhibiting resistance according to the command signal.

10. The solid-state power controller according to claim 1 or 2, in, The semiconductor switching unit (120) is a metal-oxide-semiconductor field-effect transistor, i.e., a MOSFET, wherein the source and drain terminals of the MOSFET are connected to the power supply line (110), and the gate terminal of the MOSFET is connected to the state machine (130).

11. The solid-state power controller according to claim 10, wherein, The state machine (130) is configured to output the command signal to the gate terminal of the MOSFET.

12. The solid-state power controller according to claim 7, further comprising: A circuit system (180) connected to the state machine (130), wherein the circuit system (180) is configured to: Monitor the state of the state machine (130), the current detected by the current sensor (140), the state of the semiconductor switching unit (120), the temperature detected by the temperature sensor (160), and / or the voltage detected by the voltage sensor (170); and The vehicle command signal, representing the state to which the state machine (130) is to transition, is output to the state machine (130).

13. The solid-state power controller according to claim 12, wherein, The circuit system (180) is also configured to be connected to an external communication line and to communicate via the external communication line.

14. An aircraft comprising: Solid-state power controller (100) according to any one of claims 1 to 13. The power source (200); as well as The load (300).

Images