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Pre-charge
Pre-charge of the powerline voltages in a high voltage Direct current, 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 inp ... [...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 (electricity), 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 capacitor, capacitance. The selection of over-current-protection devices such as fuse (electrical), 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 ... [...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 uses electrical energy exclusively from an electric vehicle battery, on-board battery pack to power one or more electric motor, electric traction motors, on which the vehicle solely relies for propulsion. This definition excludes hybrid electric vehicles (HEVs; including mild hybrid, mild, full hybrid, full and plug-in hybrids), which use internal combustion engines (ICEs) in adjunct to electric motors for propulsion; and fuel cell electric vehicles (FCEVs) and range extender, range-extended electric vehicles (REEVs), which consume fuel through a fuel cell or an ICE-driven electric generator, generator to produce electricity needed for the electric motors. BEVs have no fuel tanks and replenish their energy storage by plug-in electric vehicle, plugging into a charging station, electrical grid or getting a new bat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Engineering
Electronic engineering is a sub-discipline of electrical engineering that 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, photonics and 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 Engin ... [...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 that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the latter half of the 19th century after the commercialization of the electric telegraph, the telephone, and electrical power generation, distribution, and use. Electrical engineering is 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, Electromagnetism, electromagnetics and waves, microwave engineering, nanotechnology, electrochemistry, renewable energies, mechatronics/control ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Power-assist System
An electric bicycle, e-bike, electrically assisted pedal cycle, or electrically power assisted cycle is a 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 Bicycle pedal, pedaled by the rider and are therefore not electric motorcycles. E-bikes use Rechargeable battery, rechargeable batteries and typically are motor-powered up to . High-powered varieties can often travel up to or more than . 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 the certification and operation of more powerful two-wheelers which are often classed as electric motorcycles, such as licensing and mand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorized Bicycle
A motorized bicycle is a bicycle with an 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 ; however, in recent years larger motors have been built, allowing bikes to reach speeds of upwards of 113 km/h (70 mph). 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 Bicycle, 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 usi ... [...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". One of the programs that came out of the $32 billion expenditure was the concept of tracking friendly ("blue") forces on the field via a GPS-enabled computer system known as Blue Force Tracking (BFT). The concept of BFT was implemented by the US Army through the Force XXI Battle Command Brigade and Below (FBCB2) platform. The FBCB2 system in particular and the BFT system in general have won numerous awards and accolades, including: recognition in 2001 as one of the five best-man ... [...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. Hybrid powertrains are designed to switch from one power source to another to maximize both fuel efficiency and energy efficiency. In hybrid electric vehicles, for instance, the electric motor is more efficient at producing torque, or turning power, while the combustion engine is better for maintaining high speed. Improved efficiency, lower emissions, and reduced running costs relative to non-hybrid vehicles are three primary benefits of hybridization. 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 ... [...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 uses electrical energy exclusively from an on-board battery pack to power one or more electric traction motors, on which the vehicle solely relies for propulsion. This definition excludes hybrid electric vehicles (HEVs; including mild, full and plug-in hybrids), which use internal combustion engines (ICEs) in adjunct to electric motors for propulsion; and fuel cell electric vehicles (FCEVs) and range-extended electric vehicles (REEVs), which consume fuel through a fuel cell or an ICE-driven generator to produce electricity needed for the electric motors. BEVs have no fuel tanks and replenish their energy storage by plugging into a charging station, electrical grid or getting a new battery at a battery swap station, and use motor controllers to modulate the output engine power and torque, thus eliminating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-voltage Direct Current
A high-voltage direct current (HVDC) electric power transmission system 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. HVDC lines are commonly used for long-distance power transmission, since they require fewer conductors and incur less power loss than equivalent AC lines. HVDC also 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 as 50 and 60 Hz. This improves the stability and economy of each grid, by allowing the exchange of power between previously incompatible networks. The modern form o ... [...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, which may produce visible light. An arc discharge is initiated either by thermionic emission or by field emission. After initiation, the arc relies on thermionic emission of electrons from the electrodes supporting the arc. An arc discharge is characterized by a lower voltage than a glow discharge. 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 met ... [...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 has a set of input terminals for one or more 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 to control a circuit by an independent low-power signal and to control several circuits by one signal. They were first used in long-distance telegraph circuits as signal repeaters that transmit a refreshed copy of the incoming signal onto another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations. The traditional electromechanical relay uses an electromagnet to close or open the contacts, but relays using other operati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
