Variable speed DC drives


  1. Fluorescent lights ballasts

Magnetic ballast for single-ended compact fluorescent lamps


Electronic lights ballasts have come to be popular in latest years following claims for progressed efficiency. Overall they’re simplest a little greater efficient than the excellent magnetic ballasts and in fact, maximum of the benefit is due to the lamp being extra efficient when pushed at excessive frequency in preference to to the electronic ballast itself.

Their disadvantage – and an critical one in big installations – is that the inverter generates both harmonics in the supply cutting-edge and electrical noise (examine extra about it).

Power-component corrected sorts are getting available which reduce the harmonic problems, however at a widespread fee penalty.

Electronic ballast for fluoroscent lamps


Magnetic ballasts also generate harmonics but tiers are typically lower than the ones produced through electronic devices. They regularly incorporate a nearby electricity issue correction capacitor which act as a low impedance shunt for the harmonic currents. Consequently, the extent of distortion that propagates into the distribution machine is decrease and less troubles stand up.

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Lathe Variable Speed DC Spindle Motor (photograph credit: micro-machine-save.Com)


Variable pace controllers for DC motors are normally based on the three-phase bridge, which is also used in D.C. Transmission hyperlinks and uninterruptible power elements. It is also known as the six-pulse bridge due to the fact there are six pulses in line with cycle (one in step with half cycle consistent with phase) at the D.C. Output.

Figure 1 – Three-phase, or six-pulse, bridge


The modern-day is described by means of the series:


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