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Latching current limiter for space platform power distribution using a low voltage P-MOSFET and a normally-on SiC JFET
Abstract
Power distribution using latching current limiters (LCLs) [also known as solid-state power controllers (SSPCs)] is very common for 28- and 50-V bus voltage distribution on European satellite platforms. However, 100-V and even higher voltage distribution platforms generally do not employ the same approach as lower bus voltage platforms since the commonly employed p-MOSFET devices are not well suited for such voltage levels. This work introduces an LCL for 100-V distribution units using a composite power device consisting of a low-voltage p-MOSFET device and a high-voltage, normally-ON silicon carbide junction field effect transistor (SiC JFET). The description of the circuit and the experimental validation using a hypothetical class-2 (2.2–2.8 A), 100-V, LCL is discussed. In addition, in this work, two interesting characteristics are also proposed and validated, and automatic control of the tripping time depending on the overload severity and soft starts for capacitive inrush currents. Robustness and fast reaction, less than 500 ns under short-circuit conditions, have been demonstrated, as well as tight current regulation during overload faults.
... Recently, several proposals have been developed for current limiting functions of solid-state circuit breakers. For example, circuit breakers [12]- [14] consist of a current sensor, a latch circuit for determining the time constant, a gate drive circuit for use in the current limiting function, and a circuit breaker [15] is adapted a microcontroller contributes to short circuit, over current protection, and inrush current suppression with pulse width modulation (PWM). On the other hand, the circuit breaker device with the "thyristor dual" concept provides these functions in a monolithic integration. ...
This paper proposes a current limiting function for a self-sensing and self-triggering monolithically integrated SiC circuit breaker device. The proposed function provides the device not only with a fast-response current breaking operation but also with the current limiting operation, including supplying a constant current to the load and preventing the detection of inrush currents. This function is suitable for replacing mechanical conductors in initial charging circuits within rectifiers and safety equipment in case of overcurrent phenomena. The proposed method achieves certain constant currents through a simple variation of the gate-drive circuit with the adjustable parameters of an additional MOSFET. The mechanism of the current limiting function is verified using TCAD simulations based on certain conditions. Consequently, experimental results verified that the circuit breaker device with the current limiting function reduces the inrush current by up to 76.9% using a 500 VDC distribution circuit system.
The electrical power system (EPS) of satellites requires protection devices to isolate failures in short-circuit conditions that can occur in payloads due to various sources, such as debris, mishandling, or radiation. Latching current limiter (LCL) implemented with a pMOS power transistor is typically used for this task. Radiation can also affect the function of the LCL and compromise the mission of the satellite. Therefore, to improve radiation hardness, LCLs have been developed using different rad-hard techniques, such as the implementation of Wide BandGap (WBG) semiconductors as power switches. Gallium nitride (GaN) transistors are more resistant to radiation due to their intrinsic characteristics. In this letter, an LCL topology with a GaN power switch is presented to improve system reliability for space applications. The LCL has an integrated control circuit in 0.18
CMOS technology powered by an auxiliary source. The proposed LCL was validated by simulation and experimental tests. The LCL limited the current to the set value for a supply voltage of up to 50V and maintained a recovery time of less than 50
, under short-circuit tests.
The high-power solid-state power controller (SSPC) will be a critical component for the future electrified aircraft propulsion system. This article presents the development of a 1 kV 500 A bidirectional DC SSPC using SiC power modules and transient voltage suppression (TVS) diodes. The design procedure and implementation of the SSPC are presented in detail and the system level influence is discussed. Due to the limited power of a single switch, it is necessary to parallel and series switches for high-power SSPCs, and the corresponding challenges are investigated with possible solutions. In addition, the high peak-to-average clamping voltage ratio caused by Ldi/dt of the turn-off current commutation and foldback characteristics of high-power TVS diodes is addressed. Finally, the testing setups for the high-power SSPC are presented, and all key functions are tested for the SSPC. The power rating and specific power of the developed SSPC is superior to state-of-the-art counterparts to show the advantage of the developed one.
Solid-state power controllers (SSPCs) have been received increasing attention as they can configure the electrical system and protect the system by fast tripping mechanism at the same time. Although the high-voltage direct current (HVDC) electrical system can bring sustainable savings on the cables’ weight and losses, the protection can be considerably challenging. SSPCs have been successfully utilized for 28V DC aircraft onboard network. However, high-voltage ones are impeded by the vast over-voltage and the excessive losses generated from SSPC switching. This paper tries to fill this gap and presents the development of high-power SSPCs for a ±270VDC network of a future turboprop aircraft. Comprehensive designs of proper over-voltage suppression along with SSPC thermal management are presented in this paper. Besides, a comparative study on the SSPC device is carried out. Two prototypes, including a single MOSFET module and paralleling several discrete MOSFET devices, are built and then tested in the experiment. It has been validated that the proposed voltage clamping design can not only effectively suppress the over-voltage, but also limit the SSPC temperature increase during switching for both candidates. After comparing the conduction losses, maximum junction temperature, power density, weight and volume, the single device solution is recommended as a preferable SSPC option for future aircraft.
This paper reports on the fabrication technology and packaging strategy for 300-V 5-A silicon carbide Schottky diodes with a wide temperature operation range capability (between -170 °C and 300 °C). These diodes have been designed for harsh environment space applications such as inner Solar System exploration probes. Different endurance tests have been performed to evaluate the diode behavior when working at a high temperature and under severe thermal cycling conditions (ranged from -170 °C to 270 °C). The radiation hardness capability has been also tested. It has been found that the hermeticity of the package in a neutral atmosphere is a key aspect to avoid an electrical parameter drift. Moreover, the use of gold metallization and gold wire bonds on the anode allows reducing the diode surface and bonding degradation when compared to Al-containing technology. On the back-side cathode contact, the Ti/Ni/Au metallization and AuGe combination have shown a very good behavior. As a result, the manufactured diodes demonstrated high stability for a continuous operation at 285 °C.
DC distribution networks are able to effectively improve the energy efficiency and easy integration of distributed generations. However, the reliable DC circuit breaker is an essential requisite for the wide application of DC power. This paper proposes a self-powered solid state circuit breaker (SSCB) with a digitally controlled current-time profile for both ultrafast short-circuit protection and overcurrent protection. The fault detection unit detects short-circuit or overcurrent conditions by sensing the sampling resistance voltage and delivers these voltage signals to a low-cost microprocessor to realize the protection operation of the SSCB. A pulse width modulation (PWM) current limiting protection method with time interval T d is proposed to avoid nuisance tripping caused by inrush current during power electronic load startup. The time interval is properly selected based on the transient thermal properties of SiC JFETs. In order to verify the dynamic response of the SSCB, a SiC JFET-based circuit breaker prototype is designed and fabricated for result confirmation.
This paper presents a new ultrafast dc solid-state circuit breaker (SSCB) that uses a silicon carbide cascode as the main switching and limiting semiconductor and an isolated photovoltaic driver to control it. The proposed topology is self-powered and fully implemented with discrete parts. The SSCB's cascode can work in three different states—fully
on
during nominal operation, linear mode for current limitation, and fully
off
to disconnect the load. The time the SSCB operates in linear mode and the maximum current limit is easily set by discrete components. Control inputs have also been included to reset the SSCB after a fault has been removed or to remotely switch it
on
or
off
. This device can be used in dc distribution avoiding deterioration due to the problems associated with electric arcs and mechanical aging of moving parts, limiting inrush currents and also minimizing conduction losses respect other kind of circuit breakers. Functional, thermal, and efficiency tests have been carried out with three different 380 V prototypes. Experimental results show the excellent behavior of the SSCB, it is able to block a 380 V short circuit failure in 570 ns; the authors have not found any faster results in the literature.
Latching Current Limiters include a control loop meant at limiting the current in case of downstream failure. Such current control loop consists typically of a simple proportional feedback gain from a current measurement shunt resistance and may result in very limited phase margin for specified operating conditions. The present paper investigates the combination of a proportional and derivative feedback to mitigate the lack of stability margin, providing a comprehensive overview on designing Latching Current Limiters for stability. For illustration purpose, a LCL based on radiation hardened ITAR free components is considered. A breadboard has been manufactured and the reported phase margin measurements demonstrate performances in line with the analytic results.
The paper presents a detailed analysis of the dynamics involved in a simple latching current limiter design for a PCDU product. Key parameters like output inductance,
drain-gate capacitance, MOSFET transconductance are identified and modelled. Their effects are taken into account to design the compensation which provides enough stability margins (higher than 30º PM) in all worst case operating conditions. Based on the analysis, two different compensations and implementations are studied and compared. The selected implementation for the product results in a simple R-C network that
replaces the typical output damping found in the LCLs, leading to an optimum and cost effective product solution.
DC circuit protection applications provide a unique market opportunity for wide-bandgap (WBG) semiconductors, which are outside the conventional focus on power electronic converters. This paper presents an overview of emerging dc power systems, the needs for dc solid-state circuit breakers (SSCBs), and the benefits and advantages of various WBG SSCB concepts. Furthermore, a new class of self-powered SSCBs based on SiC or GaN normally-ON switching devices is proposed in this paper. One implementation of the SSCB concept based on a 1200 V SiC JFET experimentally demonstrated turn-off of a fault current of 125 A at a dc voltage of 400 V within 1 μs without requiring any external power supply. The SSCB detects short-circuit faults by sensing its drain-source voltage rise and draws power from the fault condition to turn off the SiC JFET. Various implementations of the SSCB concept for unipolar and bipolar capability using both SiC and GaN are also discussed from both device and circuit perspectives. It is concluded that very low ON-resistance normally-ON WBG switching devices are excellent candidates for the emerging SSCB applications.
A DC 120 V, 10-A solid-state power controller (SSPC) for switching ON and OFF power loads is described. The controller has a rectangular current limiting characteristic and a galvanically isolated programmable current limit level control interface. It uses N-channel MOSFET transistors to limit the current and has controlled turn-on and turn-off current rise and fall times. An overload switch-off time which is a function of baseplate temperature protects the SSPC MOSFETs from exceeding their derated temperature limits during any overload condition, and no single failure within the SSPC can overload the source supply. Parallel operation of SSPCs with equal current sharing during all operational modes is a design characteristic. A combined breadboard/thick film hybrid design has been manufactured and extensively tested, and its performance has been fully satisfactory. The SSPC was developed for application in the Columbus Space Station to provide a distribution switch suitable for full space qualification.
The problems associated with diversifying the SSPC is the subject for this paper. The term "diversifying" is used to describe the small alterations that should be done to the standard SSPC controller, so that it will expand the functionality of the SSPC to include: • High Current SSPC • Transistor Switches associated with the SSPC • The Essential load SSPC All alterations that are required should be external to the SSPC controller, meaning that the standard SSPC controller is not altered by this expanded functionality. These modifications have all been required on the Power Distribution Unit for the Meteosat Second Generation project (MSG PDU [AD2]), which has been developed and manufactured by Alcatel Denmark Space (ADS). The problems associated with the load of the SSPC user is another subject that is treated in this paper. Just as the single chip SSPC is discussed briefly.
The latest generation of fighter aircraft utilizes a 270Vdc power system [1]. Such high voltage DC power systems are difficult to protect with conventional circuit breakers because the current does not automatically go to zero twice per cycle during a fault like it does in an AC power system and thus arcing of the contacts is a problem. Solid state power controllers (SSPCs) are the solid state equivalent of a circuit breaker that do not arc and which can respond more rapidly to a fault than a mechanical breaker [2,4]. Present SSPCs are limited to lower voltages and currents by the available power semiconductors [3]. This paper presents design and experimental results for a SSPC that utilizes SiC power JFETs for the SSPC power switch to extend SSPC capability to higher voltages and currents in a space that is smaller than what is practically achievable with a Si power switch. Methods for testing SiC JFET devices under transient thermal conditions unique to the SSPC application was also presented.
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