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Pre-charge
Pre-charge of the powerline voltages in a high voltage DC application is a preliminary mode which limits the inrush current during the power up procedure. A high-voltage system with a large capacitive load can be exposed to high electric current during initial turn-on. This current, if not limited, can cause considerable stress or damage to the system components. In some applications, the occasion to activate the system is a rare occurrence, such as in commercial utility power distribution. In other systems such as vehicle applications, pre-charge will occur with each use of the system, multiple times per day. Precharging is implemented to increase the lifespan of electronic components and increase reliability of the high voltage system. Background: inrush currents into capacitors Inrush currents into capacitive components are a key concern in power-up stress to components. When DC input power is applied to a capacitive load, the step response of the voltage input will cause t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inrush Current Into HVDC Capacitor
Inrush current, input surge current, or switch-on surge is the maximal instantaneous input current drawn by an electrical device when first turned on. Alternating-current electric motors and transformers may draw several times their normal full-load current when first energized, for a few cycles of the input waveform. Power converters also often have inrush currents much higher than their steady-state currents, due to the charging current of the input capacitance. The selection of over-current-protection devices such as fuses and circuit breakers is made more complicated when high inrush currents must be tolerated. The over-current protection must react quickly to overload or short-circuit faults but must not interrupt the circuit when the (usually harmless) inrush current flows. Capacitors A discharged or partially charged capacitor appears as a short circuit to the source when the source voltage is higher than the potential of the capacitor. A fully discharged capacitor will take ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Battery Electric Vehicle
A battery electric vehicle (BEV), pure electric vehicle, only-electric vehicle, fully electric vehicle or all-electric vehicle is a type of electric vehicle (EV) that exclusively uses chemical energy stored in rechargeable battery packs, with no secondary source of propulsion (a hydrogen fuel cell, internal combustion engine, etc.). BEVs use electric motors and motor controllers instead of internal combustion engines (ICEs) for propulsion. They derive all power from battery packs and thus have no internal combustion engine, fuel cell, or fuel tank. BEVs include – but are not limited to – motorcycles, bicycles, scooters, skateboards, railcars, watercraft, forklifts, buses, trucks, and cars. In 2016, there were 210 million electric bikes worldwide used daily. Cumulative global sales of highway-capable light-duty pure electric car vehicles passed the one million unit milestone in September 2016. , the world's top selling all-electric car in history is the Tesla Model 3, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Engineering
Electronics engineering is a sub-discipline of electrical engineering which emerged in the early 20th century and is distinguished by the additional use of active components such as semiconductor devices to amplify and control electric current flow. Previously electrical engineering only used passive devices such as mechanical switches, resistors, inductors and capacitors. It covers fields such as: analog electronics, digital electronics, consumer electronics, embedded systems and power electronics. It is also involved in many related fields, for example solid-state physics, radio engineering, telecommunications, control systems, signal processing, systems engineering, computer engineering, instrumentation engineering, electric power control, robotics. The Institute of Electrical and Electronics Engineers (IEEE) is one of the most important professional bodies for electronics engineers in the US; the equivalent body in the UK is the Institution of Engineering and Technology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Engineering
Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the latter half of the 19th century after commercialization of the electric telegraph, the telephone, and electrical power generation, distribution, and use. Electrical engineering is now divided into a wide range of different fields, including computer engineering, systems engineering, power engineering, telecommunications, radio-frequency engineering, signal processing, instrumentation, photovoltaic cells, electronics, and optics and photonics. Many of these disciplines overlap with other engineering branches, spanning a huge number of specializations including hardware engineering, power electronics, electromagnetics and waves, microwave engineering, nanotechnology, electrochemistry, renewable energies, mechatronics/control, and electrical m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Power-assist System
An electric bicycle (e-bike, eBike, etc.) is a motorized bicycle with an integrated electric motor used to assist propulsion. Many kinds of e-bikes are available worldwide, but they generally fall into two broad categories: bikes that assist the rider's pedal-power (i.e. pedelecs) and bikes that add a throttle, integrating moped-style functionality. Both retain the ability to be pedaled by the rider and are therefore not electric motorcycles. E-bikes use rechargeable batteries and typically are motor-powered up to . High-powered varieties can often travel more than . E-bike use is growing in some markets, as they are seen as an eco-friendly and healthy alternative to cars, fossil fuel-powered mopeds and small motorcycles, and a less physically intense alternative to conventional bicycles. Depending on local laws, many e-bikes (e.g., ''pedelecs'') are legally classified as bicycles rather than mopeds or motorcycles. This exempts them from the more stringent laws regarding th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorized Bicycle
A motorized bicycle is a bicycle with an attached motor or engine and transmission used either to power the vehicle unassisted, or to assist with pedalling. Since it sometimes retains both pedals and a discrete connected drive for rider-powered propulsion, the motorized bicycle is in technical terms a true bicycle, albeit a power-assisted one. Typically they are incapable of speeds above . Powered by a variety of engine types and designs, the motorized bicycle formed the prototype for what would later become the motor driven cycle. Terminology The term motorized bicycle refers to just a bicycle combining pedal power and internal combustion engine power. However, the term could be used as an umbrella category to refer to bicycles using sources besides pedal power. Electric bicycles technically could be in the category of motorized bicycles but instead of using internal combustion engines as a combination it is driven by electric motors which power from pedals and batteries. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Future Combat System
Future Combat Systems (FCS) was the United States Army's principal modernization program from 2003 to early 2009. Formally launched in 2003, FCS was envisioned to create new brigades equipped with new manned and unmanned vehicles linked by an unprecedented fast and flexible battlefield network. The U.S. Army claimed it was their "most ambitious and far-reaching modernization" program since World War II. Between 1995 and 2009, $32 billion was expended on programs such as this, with little to show for it. In April and May 2009, Pentagon and army officials announced that the FCS vehicle-development effort would be canceled. The rest of the FCS effort would be swept into a new, pan-army program called the Army Brigade Combat Team Modernization Program. Development history The early joint DARPA–Army Future Combat Systems program to replace the M1 Abrams main battle tank and Bradley Fighting Vehicles envisioned robotic vehicles weighing under six tons each and controlled remotely b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybrid Vehicle
A hybrid vehicle is one that uses two or more distinct types of power, such as submarines that use diesel when surfaced and batteries when submerged. Other means to store energy include pressurized fluid in hydraulic hybrids. The basic principle with hybrid vehicles is that the different motors work better at different speeds; the electric motor is more efficient at producing torque, or turning power, and the combustion engine is better for maintaining high speed than a typical electric motor. Switching from one to the other at the proper time while speeding up yields a win-win in terms of energy efficiency, such that it translates into greater fuel efficiency. Vehicle types Two-wheeled and cycle-type vehicles Mopeds, electric bicycles, and even electric kick scooters are a simple form of a hybrid, powered by an internal combustion engine or electric motor and the rider's muscles. Early prototype motorcycles in the late 19th century used the same principle. * In a parall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Battery Electric Vehicles
A battery electric vehicle (BEV), pure electric vehicle, only-electric vehicle, fully electric vehicle or all-electric vehicle is a type of electric vehicle (EV) that exclusively uses chemical energy stored in rechargeable battery packs, with no secondary source of propulsion (a hydrogen fuel cell, internal combustion engine, etc.). BEVs use electric motors and motor controllers instead of internal combustion engines (ICEs) for propulsion. They derive all power from battery packs and thus have no internal combustion engine, fuel cell, or fuel tank. BEVs include – but are not limited to – motorcycles, bicycles, scooters, skateboards, railcars, watercraft, forklifts, buses, trucks, and cars. In 2016, there were 210 million electric bikes worldwide used daily. Cumulative global sales of highway-capable light-duty pure electric car vehicles passed the one million unit milestone in September 2016. , the world's top selling all-electric car in history is the Tesla Model 3, wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-voltage Direct Current
A high-voltage direct current (HVDC) electric power transmission system (also called a power superhighway or an electrical superhighway) uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) transmission systems. Most HVDC links use voltages between 100 kV and 800 kV. However, a 1,100 kV link in China was completed in 2019 over a distance of with a power capacity of 12 GW. With this dimension, intercontinental connections become possible which could help to deal with the fluctuations of wind power and photovoltaics. HVDC allows power transmission between AC transmission systems that are not synchronized. Since the power flow through an HVDC link can be controlled independently of the phase angle between source and load, it can stabilize a network against disturbances due to rapid changes in power. HVDC also allows the transfer of power between grid systems running at different frequencies, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Arc
An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (physics), plasma; the plasma may produce visible light. An arc discharge is characterized by a lower voltage than a glow discharge and relies on thermionic emission of electrons from the electrodes supporting the arc. An archaic term is voltaic arc, as used in the phrase "voltaic arc lamp". Techniques for arc suppression can be used to reduce the duration or likelihood of arc formation. In the late 19th century, Arc lamp, electric arc lighting was in wide use for Street light#Arc lamps, public lighting. Some low-pressure electric arcs are used in many applications. For example, fluorescent lamp, fluorescent tubes, mercury, sodium, and metal-halide lamps are used for lighting; xenon arc lamps have been used for movie projectors. Electric a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relay
A relay Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts An automotive-style miniature relay with the dust cover taken off A relay is an electrically operated switch. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof. Relays are used where it is necessary to control a circuit by an independent low-power signal, or where several circuits must be controlled by one signal. Relays were first used in long-distance telegraph circuits as signal repeaters: they refresh the signal coming in from one circuit by transmitting it on another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations. The traditional form of a relay uses an electromagnet to c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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