04-06-2012, 01:04 PM
MICROWAVE AUTO-TUNER [MAT]
MICROWAVE AUTO-TUNER [MAT].pptx (Size: 2.28 MB / Downloads: 23)
What is tuner?
Tuner is a device which tune at particular frequency. With minimum own loss & reflected loss due to the mismatch between source & load resistance.
Matching the source and load to the transmission line or waveguide in a general microwave network is necessary to deliver maximum power from the source to the load.(this is basically called tuning)
Usage of manual tuner is limited only to the applications where fixed loads are used.
Consequently it becomes a specific purpose device.
For increasing the accuracy of impedance matching of the source and the load and to get maximum power at the applicator irrespective of varying load, automation of the tuner seems to be a bright option.
Drawbacks of the existing manual tuning system
Any change in o/p due to varying load has no effect on input.
MORE power is reflected back due to improper matching
Increased standing wave ratio.
This leads to damage to generator.
INACCURATE impedance match can result in internal heating of the system.
Speed and Precision are compromised.
Human control is prone to errors when used for a longer period resulting in fall in performance.
Small Bandwidth.
ANALYSIS OF DOUBLE STUB AND THREE STUB TUNERS
Because the stub distance l from the load depends on the load impedance to be matched, the single-stub tuner is inconvenient if several different load impedances are to be matched, each requiring a different value for l.
The double-stub tuner provides an alternative matching method in which two stubs are used, one at the load and another at a fixed distance l from the load, where typically, l = λ/8.
Only the stub lengths d1, d2 need to be adjusted to match the load impedance.
ANALYSIS OF THE GENERAL PID CONTROLLER LOGIC
When working with applications where control of the system output due to changes in the reference value or state is needed, implementation of a control algorithm may be necessary.
Many control solutions have been used over the time, but the PID controller has become the ‘industry standard’ due to its simplicity and good performance.
Unlike simple control algorithms, the PID controller is capable of manipulating the process inputs based on the history and rate of change of the signal. This gives a more accurate and stable control method.