ZVS BASED LAMP LIFE EXTENDER

Zero voltage switching (ZVS) is a modern day topology that is best defined as the conversion of conventional square wave power during the on-time of the switch along with resonant switching transitions. In simple words, zero voltage switching can be explained as the power supply to a load that gets switched on or off only in the case when the output voltage becomes 0 Volts. The ZVS technique allows a device to operate at a higher frequency with higher input voltages more efficiently. Zero voltage switching topologies provide the user with lossless switching transitions and experience zero power losses during discharging. The controllers that employ the ZVS topology are usually consisted of TRIACs instead of mechanical relays. This gives zero voltage switching an advantage over other types of switching methods that use relays as they reduce the chances of arcing (sparking).

Zero voltage switching is a power electronics concept that can successfully extend the life of a controller along with the load that is to be controlled. Thus, ZVS are now commonly applied in our everyday incandescent lamps in order to increase their life. Incandescent lamp lights are prone to exhibit very low resistances in cold environments. This makes them draw a very high value of current when turned on, leading to a fast failure of their operation. So, in order to solve this predicament engineers, technologists and other specialists came up with the ingenious idea to incorporate the zero voltage switching topology in incandescent lamps to prolong their glowing life. Engineering students, particularly belonging to the department of electrical engineering, saw the potential that the methodology carried and set on the path to bring further improvements to the technique by employing it as their final year project. Though initially not quite as famous a final year project as home automation systems based on GSM modules or speed control of DC motors etc., it is gradually gaining more and more attention slowly. Students looking forward to specializing in power electronics field have quite keenly chosen ZVS based lamp life extenders as their projects.

The low resistance of incandescent lamps and their randomly switching operation may lead to a switch of the load at peak supply voltage. During the abrupt peak supply voltage switching on process, the current shoots up more than the desired value and causes the untimely failure of the lamp to glow. To overcome this predicament, engineers have designed a potentially useful solution that involves a TRIAC to control the precise switch ON time by illuminating it exactly after the zero cross point of the supply voltages waveform is detected. This leads to an end result of the current waveform rising from a value of zero when the switch is turned on to a full value and in doing so, leads to an increase in the lamps glowing light life. The ZVS based lamp life extender also makes use of a comparator for the ZVS output with the ZVS being used as a reference interrupt to be supplied to the microcontroller present in the project. Lastly, the project is also incorporated with a push button that allows the lamp to steadily draw current from zero and up to a full value during the switching on state of the supply voltage.

Lamp life extenders based on zero voltage switching techniques have proved to be a very efficient, inexpensive and simple way of ensuring that a lamps light is prolonged and does not get extinguished permanently before time. Engineers can make the project much more efficient if three TRIACs were to be used, one for each of three phases for the three-phase load switching method.