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Load Dump
Load dump means the disconnection of a powered load. It can cause two problems: * failure of supply to equipment or customers * large voltage spikes from the inductive generator(s) In automotive electronics, it refers to the disconnection of the vehicle battery from the alternator while the battery is being charged. Due to such a disconnection of the battery, other loads connected to the alternator experience a surge in the voltage on the battery bus. This surge may be as high as 120 volts and the surge may take up to 400 ms to decay. It is typically clamped to 40 V in 12 V vehicles and about 60 V in 24 V systems. Overview The field winding of an alternator has a large inductance. When the vehicle battery is being charged, the alternator generates a large current, the magnitude of which is controlled by the current in the field winding. If the battery becomes disconnected while it is being charged the load on the alternator suddenly decreases. However, the vehicle's voltage regu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Automotive Electronics
Automotive electronics are electronic systems used in vehicles, including engine management, ignition, radio, carputers, telematics, in-car entertainment systems, and others. Ignition, engine and transmission electronics are also found in trucks, motorcycles, off-road vehicles, and other internal combustion powered machinery such as forklifts, tractors and excavators. Related elements for control of relevant electrical systems are also found on hybrid vehicles and electric cars. Electronic systems have become an increasingly large component of the cost of an automobile, from only around 1% of its value in 1950 to around 30% in 2010. Modern electric cars rely on power electronics for the main propulsion motor control, as well as managing the battery system. Future autonomous cars will rely on powerful computer systems, an array of sensors, networking, and satellite navigation, all of which will require electronics. History The earliest electronic systems available as fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vehicle Battery
An automotive battery, or car battery, is a usually 12 Volt lead-acid rechargeable battery that is used to start a motor vehicle, and to power lights, screen wiper etc. while the engine is off. Its main purpose is to provide an electric current to the electric-powered starting motor, which in turn starts the chemically-powered internal combustion engine that actually propels the vehicle. Once the engine is running, power for the car's electrical systems is still supplied by the battery, with the alternator charging the battery as demands increase or decrease. Battery in modern cars Gasoline and diesel engine Typically, starting uses less than three percent of the battery capacity. For this reason, automotive batteries are designed to deliver maximum current for a short period of time. They are sometimes referred to as "SLI batteries" for this reason, for starting, lighting and ignition. SLI batteries are not designed for deep discharging, and a full discharge can reduce the ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternator
An alternator (or synchronous generator) is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.Gordon R. Selmon, ''Magnetoelectric Devices'', John Wiley and Sons, 1966 no ISBN pp. 391-393 Occasionally, a linear alternator or a rotating armature with a stationary magnetic field is used. In principle, any AC electrical generator can be called an alternator, but usually, the term refers to small rotating machines driven by automotive and other internal combustion engines. An alternator that uses a permanent magnet for its magnetic field is called a magneto. Alternators in power stations driven by steam turbines are called turbo-alternators. Large 50 or 60 Hz three-phase alternators in power plants generate most of the world's electric power, which is distributed by electric power grids. History ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inductance
Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The electric current produces a magnetic field around the conductor. The magnetic field strength depends on the magnitude of the electric current, and therefore follows any changes in the magnitude of the current. From Faraday's law of induction, any change in magnetic field through a circuit induces an electromotive force (EMF) (voltage) in the conductors, a process known as electromagnetic induction. This induced voltage created by the changing current has the effect of opposing the change in current. This is stated by Lenz's law, and the voltage is called ''back EMF''. Inductance is defined as the ratio of the induced voltage to the rate of change of current causing it. It is a proportionality constant that depends on the geometry of circuit conductors (e.g., cross-section area and length) and the magnetic permeability of the conductor and nearby materials. An ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field Current
A field coil is an electromagnet used to generate a magnetic field in an electro-magnetic machine, typically a rotating electrical machine such as a electric motor, motor or electrical generator, generator. It consists of a coil of wire through which the field current flows. In a rotating machine, the field coils are wound on an iron magnetic core which guides the magnetic field lines. The magnetic core is in two parts; a stator which is stationary, and a rotor (electric), rotor, which rotates within it. The magnetic field lines pass in a continuous loop or magnetic circuit from the stator through the rotor and back through the stator again. The field coils may be on the stator or on the rotor. The magnetic path is characterized by ''poles'', locations at equal angles around the rotor at which the magnetic field lines pass from stator to rotor or vice versa. The stator (and rotor) are classified by the number of poles they have. Most arrangements use one field coil per po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transient Voltage Suppression Diode
A transient-voltage-suppression (TVS) diode, also transil, transorb or thyrector, is an electronic component used to protect electronics from voltage spikes induced on connected wires. Description The device operates by shunting excess current when the induced voltage exceeds the avalanche breakdown potential. It is a clamping device, suppressing all overvoltages above its breakdown voltage. It automatically resets when the overvoltage goes away, but absorbs much more of the transient energy internally than a similarly rated crowbar device. A transient-voltage-suppression diode may be either unidirectional or bidirectional. A unidirectional device operates as a rectifier in the forward direction like any other avalanche diode, but is made and tested to handle very large peak currents. A bidirectional transient-voltage-suppression diode can be represented by two mutually opposing avalanche diodes in series with one another and connected in parallel with the circuit to be pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Varistors
A varistor (a.k.a. voltage-dependent resistor (VDR)) is a surge protecting electronic component with an electrical resistance that varies with the applied voltage. It has a nonlinear, non- ohmic current–voltage characteristic that is similar to that of a diode. Unlike a diode however, it has the same characteristic for both directions of traversing current. Traditionally, varistors were constructed by connecting two rectifiers, such as the copper-oxide or germanium-oxide rectifier in antiparallel configuration. At low voltage the varistor has a high electrical resistance which decreases as the voltage is raised. Modern varistors are primarily based on sintered ceramic metal-oxide materials which exhibit directional behavior only on a microscopic scale. This type is commonly known as the metal-oxide varistor (MOV). Varistors are used as control or compensation elements in circuits either to provide optimal operating conditions or to protect against excessive transient voltage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO 7637
ISO 7637 Road vehicles -- Electrical disturbances from conduction and coupling is an international electromagnetic compatibility vehicle standard published by the International Organization for Standardization (ISO), that relates to 12- and 24-volt electrical systems. , four parts of ISO 7637 have been published, and one is in development (part 4): * ISO 7637-1 (last revised ) Definitions and general considerations * ISO 7637-2 (last revised ) Electrical transient conduction along supply lines only * ISO 7637-3 (last revised ) Electrical transient transmission by capacitive and inductive coupling via lines other than supply lines * ISO 7637-4 Electrical transient conduction along shielded high voltage supply lines only * ISO 7637-5 (last revised ) Enhanced definitions and verification methods for harmonization of pulse generators according to ISO 7637 There are several distinct electrical transient waveforms that are required from this testing to ISO 7637-2. These pulses or wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
