Author Archives | Jean Pollefliet

Jean Pollefliet - who has written 7 posts on PowerGuru - Power Electronics Information Portal.

Professor Dr. Jean Pollefliet is the author of several best-selling textbooks in Flanders and the Netherlands

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High Frequency Inductive Heating

Posted on 06 February 2019

  Especially in the metal industry it is often necessary to heat objects, possibly for pouring, soldering, case hardening, melting or tempering of these parts. Mostly the heat is generated outside the object and via radiation or convection the heat is transferred to the object or work piece. A much more elegant method is to [...]

Closed loop sensor with flux-gate technology

Posted on 15 January 2019

  Flux gate sensor The flux gate principle is familiar from the flux-gate magnetometers. These were developed during the second world war and used by low flying aircraft to detect submarines. These days fluxgate sensors are used in gyro compasses and in lab equipment to measure remanent magnetism for example. The flux-gate magnetometer can measure [...]

Basics of EMC and EMI

Posted on 27 December 2019

  Originally electronics was synonymous with telecommunications (radio, television, telephony). During operation these electronic devices often produced frequencies and harmonics which interfered with the correct operation of other equipment. These undesirable effects were known as RFI (RFI = radio frequency interference = high-frequency disturbance). Since the last few decades the number of electrical and electronic [...]

Angular Position Sensors (Shaft Angle Transducer)

Posted on 09 December 2019

  Almost every machine or industrial process contains one or more rotating shafts. It is therefore important in most instrumentation systems or control systems to be able to measure the exact shaft angle of a mechanical shaft. This angular data can be used to control position, speed or acceleration of a mechanism. Standard shaft angle [...]

The Skin Effect

Posted on 25 September 2019

  If a DC current I flows through a conductor with diameter d, then the current density is J = \frac{4I}{\pi d^2} (A/mm2) and is constant throughout the cross-sectional area. In the case of an AC current this is not so. We can visualise this by imagining a conductor (fig. 1) as being composed of [...]

Hall Effect Sensors

Posted on 17 September 2019

  Hall effect If we place a current carrying conductor or semiconductor in a perpendicular magnetic field B (fig. 1) then an electric field arises perpendicular to the I-B surface. This effect is known as the Hall-effect. This effect was discovered in 1879 by the American physicist Edwin Herbert Hall. Figure 1. Hall effect Consider [...]

Opto-electronics

Posted on 04 September 2019

  LED (Light Emitting Diode) The light emitting diode (LED) has been used for years as a signal lamp, as number indicator and as a light emitting transmitter in an opto-coupler. In recent years the LED is becoming ever more popular as a light source. The operating principle of the LED rests on the release [...]