Short-circuit Protection Research Articles

SYNTHESIS OF LOGIC CIRCUITS WITH PROGRAMMABLE LOGIC CONTROLLER

The peculiarities of the synthesis and simulation of logical circuits in the Siemens Programmable logic controller-LOGO are considered. The idea is particularly suitable for studying logical schemes in non-electronic technical specialties due to the specifics of work in the programming environment of this type of controllers and the provided that reduced of the simulation. The main objective is to combine the programming and mastery of the synthesis of logical circuits.The program environment of the LOGO Kontroler with its eight basic logic functions and 33 special functions allows the study and mastering of the schemes even without the physical use of the controller this is one of the complex controllers, through which are given examples and can be successfully replaced by similar analogues of other companies. Access to the information could be protected by a password. The range includes power models-DC 12 V; AC/DC 24 V and 115/230 V. For some models in the series, the operating voltage limits are very wide, for example LOGO! 12/24RC works with voltages from 10.8 to 28.8 VDC, a LOGO! 230RC with voltages from 85 to 265 VAC. The logical module features are 8 digital inputs, LOGO! 12/24RC and LOGO! 12/24RC Two of the inputs can be configured as analog inputs with a range of 0-10 V. In the event that work with signals 4-20 mA is required, it is necessary to add a precision resistor parallel to the corresponding input. The resistor must be installed in close proximity to the terminals of the module, if possibleThe resistor must be mounted in close proximity to the terminals of the module, if possible. The resistor is 250 cm/0.250 W/0.1%, the input voltage will vary from 1 to 5 V. Other features of the series are: 4 relay outputs (for LOGO! 24 transistor, with built-in short circuit protection; operating temperature range from 0 to + 55 o C; 80 h operation of the internal clock when power is disconnected; 8 logical functions).Kontroler the Siemens LOGO! Satisfies the requirements for a logical controller for learning purposes on the one hand and the main criteria for selecting a controller on the other. A compact programmable logic controllers used in automation as a relay proxy.It does not cost more than a few relays and its programming is so flexible as connecting the relay. Its only drawback is the fixed number of inputs and outputs and the small memory for programs and data, but it is especially suitable for getting acquainted with Logical schemes for training in non-electronic technical specialties.

Design Considerations and Development of an Innovative Gate Driver for Medium-Voltage Power Devices With High $dv/dt$

Medium-voltage (MV) silicon carbide (SiC) devices have opened up new areas of applications which were previously dominated by silicon-based IGBTs. From the perspective of a power converter design, the development of MV SiC devices eliminates the need for series connected architectures, control of multilevel converter topologies which are necessary for MV applications, and the inherent reliability issues associated with it. However, when SiC devices are used in these applications, they are exposed to a high peak stress (5–10 kV) and a very high $dv/dt$ (10–100 kV/ $\mu$ s). Using these devices calls for a gate driver with a dc–dc isolation stage that has ultralow coupling capacitance in addition to be able to withstand the high isolation voltage. This paper presents a new MV gate driver design to address these issues while maintaining a minimal footprint for the gate driver. An MV isolation transformer is designed with a low interwinding capacitance, while maintaining the clearance, creepage, as well as insulation standards. A dc isolation test has been performed to validate the integrity of the insulating material. The key features include low input common mode current, and a short-circuit protection scheme specifically designed for 10 kV SiC mosfet s. The performance of the gate driver is evaluated using double pulse tests and continuous tests. Experimental results validate the advantages of the gate driver and its application for MV SiC devices exhibiting very high $dv/dt$ . The proposed gate driver concept is aimed at providing an efficient and reliable method to drive MV SiC devices.

Partially Rated Power Flow Control Converter Modeling for Low-Voltage DC Grids

Scalable and robust low-voltage direct current (LVdc) distribution networks require solutions, allowing flexible power flow control and reliable short-circuit protection. In this paper, the continuous full-order large- and small-signal models of a partially rated power flow control converter (PFCC) are derived utilizing the generalized averaging method. The large-signal model of the PFCC is coupled with a model of the LVdc grid. Due to the state-space representation, the combined model of the PFCC and the LVdc grid is suitable for easy algorithmization, and efficient simulation. These advantages make them essential tools for studying and optimizing of scalable LVdc systems with decentralized power flow control based on the PFCC. The PFCC models provide insights into controller design and stability analysis. The models are experimentally validated, and the functionality of the PFCC is demonstrated in a laboratory-scale microgrid.

Accounting power supply schemes for traction substations in the calculation of short circuits in the AC traction network

When calculating short-circuit currents in the AC traction network, it is assumed that each of the traction substations receives power from uncoupled external power supply sources with known resistances. In some cases, especially when powering a group of traction substations from a high-voltage power line of a longitudinal power supply, the external power supply system affects not only the magnitude of short-circuit currents, but also their redistribution between adjacent traction substations of the interstation area where this circuit is considered. Such unrecorded redistribution can have a negative effect on short circuit protection. The article considers the equivalent circuit of the traction network, taking into account resistance of the external power supply system. Particular attention is paid to the fact that in replacement circuits of direct and negative sequence value of reduced resistance of one phase of a multiwinding transformer, calculated from the short circuit voltage, does not depend on the connection scheme of its windings. It is noted that in some cases it is difficult to obtain a complete scheme of an external power supply system. Considering that the short circuit in the traction network for the external power supply system is remote, it is proposed taking into account the reference network or traction substations as power sources, from which high-voltage transmission lines power the traction substations. Resistance of the supporting substations as power sources must takes into account connected equivalent power system.Such equivalenting should be carried out by known values of currents or short-circuit powers at the inputs of the reference substation or, if such information is not available, by the rated values of the switched-off currents or powers of the switches of high-voltage line connections.The following power schemes for traction substations are considered: each from its own supporting substation, which is part of an electrically uncoupled external power supply system; from the double-circuit high-voltage line of longitudinal power supply when it is powered from different supporting substations; from the supporting network substation, the traction substation receives power from two lines, and from this the traction substations receive power from two lines in a circle pattern.These three common cases cover all the most common power schemes for traction substations. For each of them formulas are given to determine the resulting equivalent resistance of the external power supply circuit, which should be taken into account in the replacement circuit of the traction network.

Powerful High-Voltage DC Power Sources with High-Frequency Conversion

A series of high-voltage (20–50 kV) DC power sources (1–10 kW) was developed based on the circuit of high-frequency conversion with wide-range regulation of the output voltage via conversion frequency tuning. A sinusoidal current shape provides switching of power transistors at the zero current and the short-circuit protection in a load. The source provides an output voltage with small ripples and, when powered from a three-phase network, it does not require a smoothing mains filter.

Driving Circuit Design of Three-level Inverter for Mining Transport Machine

For the three-level inverter of mining, in order to improve the operating efficiency of the system and reduce the overshoot of current and voltage, and extend the life of the motor and inverter, the new high-voltage high-power IGBT drive module 2QD30A17K-I is used to design the drive circuit, analyzed the working principle of drive circuit, designed over-current, short circuit protection, and under-voltage protection circuit, gives the basic three-level drive circuit schematic diagram, parameter calculation and selection of components, experimental verification verifies the feasibility and correctness of the drive circuit, it can be promoted and applied in the coal mining industry.

Short-Circuit Characterization and Protection of 10-kV SiC <sc>mosfet</sc>

This paper presents the characterization of the temperature-dependent short-circuit performance of a Gen3 10 kV/20 A silicon carbide (SiC) mosfet . The test platform consisting of a phase-leg configuration and a fast speed 10-kV solid state circuit breaker, with temperature control, is introduced in detail. A novel FPGA-based short-circuit protection circuit having a response time of 1.5 μ s is proposed and integrated into the gate driver. The short-circuit protection is validated through the platform. The short-circuit characteristics for both the hard switching fault and fault under load (FUL) types at various dc-link voltages (from 500 V to 6 kV) are tested and discussed. The saturation current increases with dc-link voltage and achieves 360 A at 6 kV. Different from low voltage SiC devices, there is no current spike in FUL type of fault. The temperature-dependent short-circuit performance is also presented from 25 to 125 °C. The difference of short-circuit waveforms at various initial junction temperatures can be neglected. A thermal model of the 10-kV SiC mosfet is built for the junction temperature estimation during the short circuit and for analysis of the initial junction temperature impact on the short-circuit performance.

High Performance Autonomous Charge Equalization in Series Connected Batteries

In this paper, a novel balancing circuit is proposed, which is well suited to aerospace electronics, as it allows for the use of off-the-shelf radiation tolerant components. The new design was examined analytically with and without a zero-voltage switching topology. Its performance was compared to other popular battery balancing circuits. Further, an equation was derived, which can be used to estimate the time to balance. The proposed balancer circuit was evaluated using forward and several flyback transformer types, and with the use of static and dynamic testing, the design was also evaluated under fault conditions as it provides a short-circuit protection. It was determined experimentally that the proposed design achieves an efficiency of up to 84%.

7.2-kV Single-Stage Solid-State Transformer Based on the Current-Fed Series Resonant Converter and 15-kV SiC <sc>mosfet</sc>s

This paper proposes a novel two-level single-stage direct ac–ac converter for realizing a 7.2-kV medium-voltage (MV) solid-state transformer (SST) based on 15-kV SiC mosfet s. A new current-fed series resonant converter (CFSRC) topology is proposed to address major challenges in MV ac–ac converters such as achieving zero-voltage switching (ZVS) for the MV mosfet s across wide voltage and load ranges and minimizing system capacitance. The topology is analyzed with both time-domain analysis and first harmonic approximation to provide useful equations for circuit design. Constant deadtime strategy is adopted, allowing partial ZVS to occur at low-voltage (LV) levels. ZVS behavior over wide voltage range is investigated, and calculation of the associated loss from partial ZVS is presented. System parameters are optimized based on the tradeoff between conduction loss and switching loss. The 15-kV mosfet has been tested continuously at a park voltage of 10 kV and 37 kHz, indicating stable device operation and an extremely high voltage × frequency figure of merit. Moreover, inherent cycle-by-cycle current limiting in the proposed CFSRC under output short-circuit circumstance is realized by paralleling diodes to the LV resonant capacitors. Without employing any additional current sensors, the input and circulating currents are limited to a safe range automatically when the short-circuit occurs. This paper presents detailed short-circuit protection operating principles and peak resonant current equation to aid the design of the resonant tank. A full-scale and compact SST that converts 7.2 kV ac to 240 V ac is developed to verify the theoretical analysis. This is the highest reported voltage rating for two-level-based power converters without device series connection. ZVS is verified and achieved over wide voltage and load ranges with a peak efficiency of 97.8%. A short-circuit experiment is conducted at 3-kV peak voltage to verify the analysis. Experimental results closely match the theoretical analysis.

Реализация защит от аварийных режимов в электроприводе вентиляторов малой мощности

The paper deals with the design of an inverter supplying power to the drive of fans cooling the subway car brake resistors and the traction electric drive power converter’s heat sink fins. Since this fan drive is a low-capacity one, it was decided to make the inverter for it with the minimal possible cost. To achieve the desired objective, it was decided to exclude protections from certain very unlikely emergency modes. It was proposed to use cheap IC chips of transistor switch drivers and to implement short-circuit protection using current transformers. The current transformers have a very large bandwidth and can be used in the application in question not only to protect the motor, but also to protect the inverter transistor switches. The current transformer signals are rectified by a low-capacity rectifier, thus making it possible to eliminate separate processing of the phase current positive and negative half-waves. The rectified signals are fed to the input of the protection circuit implemented on operational amplifiers. The total time of short-circuit protection system response to the input signal is about 1 μs. In measuring the current transformers’ output signals, it is possible to obtain a sufficient amount of data for making overload protection, phase open-circuit fault protection, load imbalance protection, and thermal protection. Emergency modes detection algorithms for implementing them in the scope of the electric drive microprocessor control system are presented. The proposed solutions were investigated on a mathematical model and on the inverter mockup prototype, and the obtained results have demonstrated their efficiency. &nbsp

Improving the energy efficiency of vehicle electrical systems

The article discusses the main directions of improving the efficiency of electrical systems (EES) and power supply systems (PSS) of motor vehicles (MV) of traditional design, using internal combustion engines (ICE) for movement, the main trends in the development of MV. There are shown technical solutions aimed at reducing fuel consumption. The analysis of the current PSS, indicating its main shortcomings is given. It is shown that increasing the maximum output current of the generator set to 20 A leads to an increase in engine fuel consumption by 10-15%. Fuel consumption for the drive of the generator set on modern vehicles with gasoline engines reaches 20% of the total fuel consumption in the city. A method of simulation of EES in operation and analysis of the concept of power supply system management, aimed at reducing fuel consumption, is given. The main ways of increasing the efficiency of EES using the developed voltage regulator built into the control panel SCHU-5 are given. The advantage of the developed voltage regulator is a significant expansion of diagnostic functions. This is an indication of the increased voltage of the network, since the operation of the fuel injection system control unit already at a voltage of 17.5 V leads to its failure, and the cost of this unit is more than 9,000 rubles, which is significantly higher than the cost of the voltage regulator. Multi-function voltage regulator has the function of controlling the growth of the load. This function ensures the stable operation of the engine in the mode of forced idling and eliminates shock loads on the generator drive belt. The circuit voltage regulator has short-circuit protection in the circuit control lamp. In the multifunctional voltage regulator, thermal protection is introduced, which increases the reliability of the generator set operation in severe operating conditions at elevated ambient temperatures.

Transient junction temperature estimation of IGBT using improved thermal model

Insulated gate bipolar transistors (IGBTs) under some extreme conditions, such as the variation of the load or outside disturbance, will cause a transient junction temperature rise. This temperature step is one of the major causes of IGBT failure. However, in the traditional Cauer-type thermal model, the temperature of each layer inside IGBT is assumed to be well distributed. This assumption will impair the accuracy of the thermal analysis. In this paper, an improved thermal model that can accurately predict the junction temperature under transient temperature rise is proposed, based on the accurate structure description of IGBT with an active volume. The theoretical expression of the temperature derived from the improved model is verified by finite element analysis (FEA). The outcome of the proposed model can provide a design reference for short circuit protection and failure analysis.

RANCANG BANGUN PERANGKAT PEMBANGKIT PWM BIPOLAR

Electrical power settings, both AC and DC can be done by linear or switching. Controlled loads may be motors, heating elements or incandescent lamps. Generally the efficiency of load power control by way of switching is better than linear way so the way switching is widely used today. Switching also allows for automatic, remote and wireless control In load power management system with microcontroller, PWM generator circuit output is used for control of power switch. The output pulse can be TTL standard or with lower amplitude and on the control of the H bridge circuit required bipolar PWM with additional dead band on each side of the pulse ride. The bipolar PWM generator designed in this study has an output with TTL standard with a dead band circuit and a short circuit protection for VCC = 5 volts and a ground path, Testing with no load and short circuit in low and high output states is as follows. VOL(min) = 0.4 volts, VOH(max) = 4.2 volts. The short circuit of output to high GND is 100 mA and short circuit current to VCC path at low output is 90 mA, The output frequency of bipolar pulses is, 50, 100, 1k, 10k and 20k Hz with 10μs dead band

An Improved IGBT Short-Circuit Protection Method With Self-Adaptive Blanking Circuit Based on V CE Measurement

IGBT short-circuit protection is the key factor to improve the reliability of the power electronics system. The conventional short-circuit protection method based on $V_{CE}$ measurement detects the collector–emitter voltage of an IGBT to determine whether the IGBT short-circuit fault occurs. The blanking circuit is needed in this kind of protection method to avoid the false triggering of the short-circuit protection during IGBT turn-on transient. However, this blanking circuit should be carefully designed for different types of IGBT modules. In order to make the IGBT short-circuit protection circuit suitable for the tolerance of IGBT modules, a self-adaptive blanking circuit combined with the aforementioned short-circuit protection method based on $V_{CE}$ measurement is proposed. The proposed method is achieved by feeding back the required minimum blanking time interval which is decided by comparing the desaturation reference voltage with the collector–emitter voltage. The short-circuit protection delay time for the conventional circuit and the proposed circuit are compared. Experimental results are included to prove the effectiveness of the proposed circuit.

A Very High-Gain-Modular Three-Phase AC/DC Soft-Switched Converter Featuring High-Gain ZCS Output Rectifier Modules Without Using Step-Up Transformers for a DC Grid in Wind Systems

This paper presents a new modular ac/dc step-up soft-switched converter with unity turns ratio high-frequency transformers for medium-voltage (MV) dc grid in wind energy systems. In the proposed converter, the three-phase boost rectifier is combined with step-up resonant circuits and high-gain output rectifier modules (called voltage quadrupler modules) to form a modular step-up power conversion unit. As a result, the proposed converter is able to achieve very high voltage gain without using any medium-to-high frequency transformers with very large turns ratio, which greatly simplifies the insulation requirement and design of the high-frequency transformer. In addition, soft-switching operations are achieved in all the semiconductor devices to maintain high efficiency. The techniques to ensure voltage balancing across the dc-link capacitors and to achieve output short-circuit protection will be discussed in this paper. To realize high-frequency MV operation, silicon carbide (SiC) devices are utilized in the converter implementation on a 1.5 MW, 690 VAC/40 kV converter system to validate the performance of the proposed circuit. Experimental results on a 3.5 kW, 145 VAC/6.2 kV, 95.4% efficiency SiC-based laboratory-scale proof-of-concept prototype are then provided to highlight the merits of this work.

An Instantaneously Triggered Short-Circuit Protection Architecture for Boost Switching DC/DC Converters

This paper presents a protection circuit architecture that helps us to reduce the chances of damages in a boost switching converter due to fault conditions of output short-to-ground or power-switch short-circuits. Those two short-circuit faults can cause the inductor current to run away and result in damages. The proposed protection circuit can detect those two fault conditions within a few microseconds and then isolate the converter from its power supply. The fault detection is implemented by sensing the voltage drop across the primary inductor in a 1:1 coupled transformer which replaces the single-winding inductor in a boost converter. If a short-circuit fault happens at either the output load or at the power switch, the secondary inductor will shoot current to turn off a pass PMOSFET, which disconnects the primary inductor from the input supply. The protection circuit was built on the top of a commercial boost converter and was verified under short-circuit faults over a wide load current range. The proposed protection structure effectively reduced the inductor current overshoot during short-circuit event at the expenses of 1.2% drop of the peak efficiency during normal operation.

An Experimental Demonstration of Short Circuit Protection of SiC Devices

An experimental demonstration of an effective short circuit protection scheme for SiC MOSFETs is presented in this paper. Measurements of the static characteristics of the SiC device before and after the short circuit events were obtained to evince that the device remained in good health. An ultra-fast short circuit protection scheme is implemented given the observed lower short-circuit withstand of present SiC devices. It is shown that the integrity of the SiC device was protected after one-hundred short circuit events.

A New Configuration Using PWM Current Source Converters in Low-Voltage Turbine-Based Wind Energy Conversion Systems

Current source converter (CSC)-based wind energy conversion systems (WECSs) are recently gaining increasingly attention due to its reliable short-circuit protection. However, all existing CSC-based configurations are proposed for medium-voltage (MV) (3–4 kV) wind turbine systems, but not for low-voltage (LV) (690 V) systems which are dominating the market of WECS. The biggest challenge for using CSCs in LV systems is no proper switching devices in the market. This paper proposes a new configuration, where a proven modular LV voltage source converter is used as the generator-side converter to be compatible with an MV CSC. By such a design, MV CSCs are successfully used in LV systems with all advantages being inherited. In addition, this configuration features high reliability and reduced size and weight, thanks to the adoption of the modular converter. The performance of the configuration under normal and fault conditions are investigated. Apart from fulfilling traditional control objectives in WECS, a current balancing control is added to ensure safe operation. Additionally, limits and constraints of the configuration using in practice are discussed. Finally, simulation and down-scaled experimental results are presented.

Impact of Solar PV Integration on Short Circuit Current and Protection of Distribution System

Impact of Solar PV Integration on Short Circuit Current and Protection of Distribution System

Power electronic supply system with the wind turbine dedicated for average power receivers

This article presents the original project of the AC-DC-AC converter dedicated to low power wind turbines. Such a set can be a good solution for powering isolated objects that do not have access to the power grid, for example isolated houses, mountain lodges or forester's lodges, where they can replace expensive diesel engine generators. An additional source of energy in the form of a mini-wind farm is also a good alternative to yachts, marinas and tent sites, which are characterized by relatively low power consumption. This article presents a designed low power wind converter that is dedicated to these applications. The main design idea of the authors was to create a device that converts the very wide range input voltage directly to a stable 230VAC output voltage without the battery buffer. Authors focused on maximum safety of using and service. The converter contains the thermal protection, short-circuit protection and overvoltage protection. The components have been selected in such a way as to ensure that the device functions as efficiently as possible.