Modern Power Electronics and Drivers

We consider drives built around single phase induction and single phase synchronous motors in this section. Motor Diagram Use of a variable speed drive instead of a fixed speed motor plus external mechanical control yields many advantages. It saves energy significantly and enhances the performance of the drive system (i.e. the load). Energy saving can add up to some MW (Mega watt) level savings in a country due to heavy proliferation of single phase motors in any country. (Note: The largest share of power consumption in most countries attributed to single phase motor). Motor control requires its input voltage V and frequency f be adjustable with appropriate resolutions. There are 3 alternative control modes. 1. High speed control mode 2. Low speed control mode 3. Serve control mode The drive system take power from an unregulated DC input. This is the norm for all drive systems, not only for 1 phase drives. This unregulated DC in obtained using a diode rectifier (1 phase or 3 pha...

Apart from power switching devices, the power-converter technology has also gone through significant developments in the recent past. Resonant converters specially the multi resonant converters are critical examples. High-phase-number converters is another area of development. (where the motors are no longer restricted to 3 phases). Motor technology also went through a similar phase of developments, mainly after 1980. In 1985, the development of high energy permanent magnet, known as Nd-Fe-B (Nyoaliminium Iron Boron) resulted in a set of new motors such as brussless DC motors, switch reluctant motors, hybrid stepper motor, permanent magnet linear motor ...etc. The brussless DC motor is a good alternative to conventional (brushed) DC motors, it delivers the same performance without problems associated with a mechanical commutator. Note: High energy permanent magnet materials especially Sm-Co (Samarian Cobolt) was in use prior to developing Nd-Fe-B but the high cost of Sm-Co and not ...

Motion control industry went through a revolutionary phase after 1980 following the remarkable development took place in the fields of power switching devices, high energy permanent magnets and microelectronics. Advanced and sophisticated power switching devices such as power MOSFET and IGBT came into being during that time. This made a significant change in the trend of power electronic control, producing inverters and converters capable of switching at extremely high frequencies well into MHz range. (The old Thyristor converters could not do more that about 1 KHz at that time.) This level of very high switching frequency is essentials to realize complex control functions. Circuit symbol of IGBT

Figure 1: Structure of drive system Load is the most important component. All other units are arranged to serve the requirement of the load. Any design begins with a list of specifications for the load. This depends on the type of the load and its environment. We need to answer several questions before preparing specifications. Eg: Whether one, two or four quadrant operation is necessary Whether servo or adjustable speed action is necessary Whether breaking energy is to be dissipated or returned back to the utility Whether a soft or hard start is suitable What are the range of speed and the resolution of the speed control? What are maximum torque? Is there a space restriction? Is there a noise level restriction? Is there some starting current restriction? Is there any EMI (Electro Magnetic Interference) restriction? Is there supply end restrictions? (Eg: Total Harmonic Distrotion)? Whether the energy efficiency is a prime consideration and many more. The components in ...

Role of power electronics and drivers Power controlling using electronics consider here Signal controlling is consider about controlling information Power electronics is about control of power electronically. Range of power can extend from some fraction of watt to several mega watts (MW). Drives are about the control of mechanical motion. It can be a linear motion, rotary motion or their combination. There is a greater compatibility between power electronics and drives as the former can provide smart control of power for the drives. This is evident from the varieties of fascinating motion control systems we find today. There are several terms used in the context f motion control. Motion control systems Mechatronic systems Drive systems Adjustable speed drive systems Servo drive systems Motion control system is the name used in west (Europe) to represent the low power drives (Computer pheripherals, home appliances...etc) upto several KW. Mechatronics system is the name used ...