Community hub
Recent from talks
Knowledge base stats:
Talk channels stats:
Members stats:
Electric machine
In electrical engineering, an electric machine is a general term for a machine that makes use of electromagnetic forces and their interactions with voltages, currents, and movement, such as motors and generators. They are electromechanical energy converters, converting between electricity and motion. The moving parts in a machine can be rotating (rotating machines) or linear (linear machines). While transformers are occasionally called "static electric machines", they do not have moving parts and are more accurately described as electrical devices "closely related" to electrical machines.
Electric machines, in the form of synchronous and induction generators, produce about 95% of all electric power on Earth (as of early 2020s). In the form of electric motors, they consume approximately 60% of all electric power produced. Electric machines were developed in the mid 19th century and since have become a significant component of electric infrastructure. Developing more efficient electric machine technology is crucial to global conservation, green energy, and alternative energy strategy.
The basis for electric machines date back to the early 19th century, and the research and experiments of Michael Faraday in the relationship of electricity and magnetism. One of the first demonstrations of an electric machine was in 1821, with a free-hanging wire dipped into a pool of mercury, on which a permanent magnet (PM) was placed. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire. While primitive compared to modern electric machines, this experiment showed the ability to convert electric energy to motion.
Improvements to electric machines continued throughout the 19th century, however as this predated the existence of an electric power system, they struggled to gain viability and acceptance. Near the end of the 19th century, when the first electric grids came into existence, electric machines grew into more applications. Of note, the invention of the dynamo by Werner von Siemens in 1867 and invention of the first practical DC motor by Frank Sprague in 1886.
As electric power systems moved from DC to AC during the war of currents, so did electric machines. While alternators began to replace dynamos, AC motors proved more difficult. It wasn't until Nikola Tesla's invention of the induction motor that AC motors began to replace DC motors in significant quantities.
The main operating principles of electric machines take advantage of the relationship between electricity and magnetism, specifically that changes in one can create changes in the other. For example, moving a bar magnet around a wire to induce a voltage across it, or running current through a wire in a magnetic field to generate a force.
This is largely based off of Maxwell's Equations and can be analytically and mathematically complex. However, most electric machines are governed by the same 4 principles:
As current flows within a magnetic field, a force is induced that causes movement. With this movement also within the magnetic field, a voltage is induced in the machine. This induced voltage affects the current in the machine, which in turn affects the force and speed, and ultimately the induced voltage again. This feedback tends to drive the machine to an equilibrium so that the electrical energy and mechanical energy are matched (plus losses). With proper orientation of magnetic fields, wires, voltages, and currents, an electric machine can convert electric energy (electricity) to mechanical energy (motion) and vice-versa.
Hub AI
Electric machine AI simulator
(@Electric machine_simulator)
Electric machine
In electrical engineering, an electric machine is a general term for a machine that makes use of electromagnetic forces and their interactions with voltages, currents, and movement, such as motors and generators. They are electromechanical energy converters, converting between electricity and motion. The moving parts in a machine can be rotating (rotating machines) or linear (linear machines). While transformers are occasionally called "static electric machines", they do not have moving parts and are more accurately described as electrical devices "closely related" to electrical machines.
Electric machines, in the form of synchronous and induction generators, produce about 95% of all electric power on Earth (as of early 2020s). In the form of electric motors, they consume approximately 60% of all electric power produced. Electric machines were developed in the mid 19th century and since have become a significant component of electric infrastructure. Developing more efficient electric machine technology is crucial to global conservation, green energy, and alternative energy strategy.
The basis for electric machines date back to the early 19th century, and the research and experiments of Michael Faraday in the relationship of electricity and magnetism. One of the first demonstrations of an electric machine was in 1821, with a free-hanging wire dipped into a pool of mercury, on which a permanent magnet (PM) was placed. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire. While primitive compared to modern electric machines, this experiment showed the ability to convert electric energy to motion.
Improvements to electric machines continued throughout the 19th century, however as this predated the existence of an electric power system, they struggled to gain viability and acceptance. Near the end of the 19th century, when the first electric grids came into existence, electric machines grew into more applications. Of note, the invention of the dynamo by Werner von Siemens in 1867 and invention of the first practical DC motor by Frank Sprague in 1886.
As electric power systems moved from DC to AC during the war of currents, so did electric machines. While alternators began to replace dynamos, AC motors proved more difficult. It wasn't until Nikola Tesla's invention of the induction motor that AC motors began to replace DC motors in significant quantities.
The main operating principles of electric machines take advantage of the relationship between electricity and magnetism, specifically that changes in one can create changes in the other. For example, moving a bar magnet around a wire to induce a voltage across it, or running current through a wire in a magnetic field to generate a force.
This is largely based off of Maxwell's Equations and can be analytically and mathematically complex. However, most electric machines are governed by the same 4 principles:
As current flows within a magnetic field, a force is induced that causes movement. With this movement also within the magnetic field, a voltage is induced in the machine. This induced voltage affects the current in the machine, which in turn affects the force and speed, and ultimately the induced voltage again. This feedback tends to drive the machine to an equilibrium so that the electrical energy and mechanical energy are matched (plus losses). With proper orientation of magnetic fields, wires, voltages, and currents, an electric machine can convert electric energy (electricity) to mechanical energy (motion) and vice-versa.