ELECTRIC MACHINE

APPLICATIONS

Why machines and not motors or generators?Is only a mode of operation of the same machine.Why is this topic important?Many applications :over 30 machines in houseindustrytractiongenerationpositioning.Motivations

Classes of ApplicationsManufacturingDomesticAutomobilesAutonomous and remotely controlled vehiclesInformation TechnologyHealthcare

ManufacturingTo move materials and parts for processing and assemblyMilling machinesCNC machines powered by electric or hydraulic motors. Robots or manipulators - electric or hydraulic. A familiar example: pick and place robotetc.

DomesticMostly electric motors Such devices include :the coffee grinder, dishwasher, vacuum cleaner, sewing machine, video recorder, CD player, camera, personal computer, power tools, electric razors, etc.

AutomobilesBoth electric and hydraulic, e.g.:steering and suspension systems. electric windows, central door locking, sunroof operation, mirror positioning, etc. Some top of the range vehicles use in excess of one hundred motors.

Autonomous and Remotely Controlled VehiclesMostly use electric motors for: movement of the vehicle and the steering mechanism. Some vehicles are remotely controlled for use in hazardous environments such as: firefighting and bomb disposal. These may have alternative drive mechanisms such as pneumatic, for safety reasons.

Information TechnologyMotors are found in abundance in IT equipment: Personal computers:disk drives, CD drives, floppy drives etc. Printers, Fax machines, etc.

HealthcareSpecialist healthcare equipment: the dentists drill is commonly pneumatic although some are being replaced with very small electric motors. Electric wheelchairs are now much more common than they used to be, due in part to improved battery technology.Dialysis pumps etc.

The Motion ControlDepending on the application, motion control can refer to:simple on-off control, a sequencing of events, controlling the speed of a motor, moving objects from one point to anotherprecisely constraining the speed, acceleration, and position of a system throughout a move.

Drive SystemIn order to produce the required motion we need additional circuitry - apart from the motor itself - to drive and control the systemThey are referred to as power converter circuits The converter draws electrical energy from the source (e.g. mains) and supplies it to the motor at whatever voltage and frequency is necessary to achieve the required mechanical output

Drives that employ electric motors as prime movers are known as Electrical DrivesRequire prime moversDrives are systems employed for motion control

ELECTRIC DRIVES

Conventional electric drivesBulkyInefficientinflexible

Modern electric drives (With power electronic converters)SmallEfficientFlexible

Modern electric drivesInter-disciplinarySeveral research areaExpanding

Components in electric drivese.g. Single drive - sensorless vector control from Hitachi

Components in electric drivese.g. Multidrives system from ABB

Components in electric drivesMotorsDC motors - permanent magnet, wound field, brushless AC motors - induction, synchronous Applications - cost, environment Power sourcesDC batteries, fuel cell, photovoltaicAC Single- three- phase utility, wind generatorPower processorTo provide a regulated power supplyCombination of power electronic convertersMore efficient Flexible Compact AC-DC DC-DC DC-AC AC-AC

Components in electric drivesControl unitComplexity depends on performance requirementanalog- noisy, inflexible, ideally has infinite bandwidth.digital immune to noise, configurable, bandwidth is smaller than the analog controllers DSP/microprocessor flexible, lower bandwidth - DSPs perform faster operation than microprocessors (multiplication in single cycle), can perform complex estimations

Overview of AC and DC drivesDC motors : Regular maintenance, heavy, expensive, speed limitEasy control, decouple control of torque and fluxAC motors : Less maintenance, light, less expensive, high speedCoupling between torque and flux variable spatial angle between rotor and stator flux

Overview of AC and DC drivesBefore semiconductor devices were introduced (

Overview of AC and DC drivesAfter vector control drives were introduced (1980s)AC motors used in high performance applications elevators, tractions, servosAC motors favorable than DC motors however control is complex hence expensiveCost of microprocessor/semiconductors decreasing predicted 30 years ago AC motors would take over DC motors

Classification of IM drives

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