Editing Power inverter (section)

===Electric motor speed control===
Inverter circuits designed to produce a variable output voltage range are often used within motor speed controllers. The DC power for the inverter section can be derived from a normal AC wall outlet or some other source. Control and feedback circuitry is used to adjust the final output of the inverter section which will ultimately determine the speed of the motor operating under its mechanical load. Motor speed control needs are numerous and include things like: industrial motor driven equipment, electric vehicles, rail transport systems, and power tools.
(See related: [[variable-frequency drive]])
Switching states are developed for positive, negative, and zero voltages as per the patterns given in the switching Table 1. The generated gate pulses are given to each switch in accordance with the developed pattern and thus the output is obtained.

====In refrigeration compressors====
An inverter can be used to control the speed of the [[gas compressor|compressor]] motor to drive [[variable refrigerant flow]] in a [[refrigeration]] or [[air conditioning]] system to regulate system performance. Such installations are known as [[inverter compressor]]s. Traditional methods of refrigeration regulation use single-speed compressors switched on and off periodically; inverter-equipped systems have a [[variable-frequency drive]] that controls the speed of the motor and thus the compressor and cooling output. The variable-frequency AC from the inverter drives a [[brushless motor|brushless]] or [[induction motor]], the speed of which is proportional to the frequency of the AC it is fed, so the compressor can be run at variable speeds—eliminating compressor stop-start cycles increases efficiency. A [[microcontroller]] typically monitors the temperature in the space to be cooled, and adjusts the speed of the compressor to maintain the desired temperature. The additional electronics and system hardware add cost to the equipment, but can result in substantial savings in operating costs.<ref name="aia20090410">{{cite news |title=New and Cool: Variable Refrigerant Flow Systems |publisher=American Institute of Architects |newspaper=AIArchitect |date=2009-04-10 |url=https://info.aia.org/aiarchitect/thisweek09/0410/0410p_vrf.htm |access-date=2013-08-06}}</ref> The first inverter air conditioners were released by Toshiba in 1981, in Japan.<ref>{{cite web |title=Toshiba Science Museum: World's First Residential Inverter Air Conditioner |website=toshiba-mirai-kagakukan.jp |url=https://toshiba-mirai-kagakukan.jp/en/learn/history/ichigoki/1981aircon/index.htm}}</ref>