Control theoryControl theory is a field of control engineering and applied mathematics that deals with the control of dynamical systems in engineered processes and machines. The objective is to develop a model or algorithm governing the application of system inputs to drive the system to a desired state, while minimizing any delay, overshoot, or steady-state error and ensuring a level of control stability; often with the aim to achieve a degree of optimality. To do this, a controller with the requisite corrective behavior is required.
Open-loop controllerIn control theory, an open-loop controller, also called a non-feedback controller, is a control loop part of a control system in which the control action is independent of the "process output", which is the process variable that is being controlled. It does not use feedback to determine if its output has achieved the desired goal of the input command or process setpoint. There are many open-loop controls, such as on/off switching of valves, machinery, lights, motors or heaters, where the control result is known to be approximately sufficient under normal conditions without the need for feedback.
Demand responseDemand response is a change in the power consumption of an electric utility customer to better match the demand for power with the supply. Until the 21st century decrease in the cost of pumped storage and batteries electric energy could not be easily stored, so utilities have traditionally matched demand and supply by throttling the production rate of their power plants, taking generating units on or off line, or importing power from other utilities.
Mobility analogyThe mobility analogy, also called admittance analogy or Firestone analogy, is a method of representing a mechanical system by an analogous electrical system. The advantage of doing this is that there is a large body of theory and analysis techniques concerning complex electrical systems, especially in the field of filters. By converting to an electrical representation, these tools in the electrical domain can be directly applied to a mechanical system without modification.
Power supplyA power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a result, power supplies are sometimes referred to as electric power converters. Some power supplies are separate standalone pieces of equipment, while others are built into the load appliances that they power. Examples of the latter include power supplies found in desktop computers and consumer electronics devices.
Wide area synchronous gridA wide area synchronous grid (also called an "interconnection" in North America) is a three-phase electric power grid that has regional scale or greater that operates at a synchronized utility frequency and is electrically tied together during normal system conditions. Also known as synchronous zones, the most powerful is the Northern Chinese State Grid with 1,700 gigawatts (GW) of generation capacity, while the widest region served is that of the IPS/UPS system serving most countries of the former Soviet Union.
Insulated-gate bipolar transistorAn insulated-gate bipolar transistor (IGBT) is a three-terminal power semiconductor device primarily forming an electronic switch. It was developed to combine high efficiency with fast switching. It consists of four alternating layers (P–N–P–N) that are controlled by a metal–oxide–semiconductor (MOS) gate structure. Although the structure of the IGBT is topologically similar to a thyristor with a "MOS" gate (MOS-gate thyristor), the thyristor action is completely suppressed, and only the transistor action is permitted in the entire device operation range.
Tunnel diodeA tunnel diode or Esaki diode is a type of semiconductor diode that has effectively "negative resistance" due to the quantum mechanical effect called tunneling. It was invented in August 1957 by Leo Esaki, Yuriko Kurose, and Takashi Suzuki when they were working at Tokyo Tsushin Kogyo, now known as Sony. In 1973, Esaki received the Nobel Prize in Physics, jointly with Brian Josephson, for discovering the electron tunneling effect used in these diodes.
ElastanceElectrical elastance is the reciprocal of capacitance. The SI unit of elastance is the inverse farad (F−1). The concept is not widely used by electrical and electronic engineers. The value of capacitors is invariably specified in units of capacitance rather than inverse capacitance. However, it is used in theoretical work in network analysis and has some niche applications at microwave frequencies. The term elastance was coined by Oliver Heaviside through the analogy of a capacitor as a spring.
TetrodeA tetrode is a vacuum tube (called valve in British English) having four active electrodes. The four electrodes in order from the centre are: a thermionic cathode, first and second grids, and a plate (called anode in British English). There are several varieties of tetrodes, the most common being the screen-grid tube and the beam tetrode. In screen-grid tubes and beam tetrodes, the first grid is the control grid and the second grid is the screen grid. In other tetrodes one of the grids is a control grid, while the other may have a variety of functions.
