Question
Download Solution PDFWhy is the transformer of an SMPS smaller in size when compared to a transformer in a Linear power Supply of similar rating?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFSMPS (Switched-mode power supply):
- A switched-mode power supply is an electronic power supply that uses a switching regulator to convert electrical efficiently.
- Generally, SMPS transfers power from a DC or AC source to DC loads.
Advantages:
- The higher power conversion efficiency is an important advantage of a switched-mode power supply. Switched-mode power supplies may also be substantially smaller and lighter than a linear supply due to the smaller transformer size and weight.
- These are compact in size because of the smaller transformer due to higher operating frequency (typically 50 kHz – 1 MHz).
Comparison between SMPS and Linear power supply:
|
parameter |
Linear power supply |
Switched-mode power supply |
|
operation |
It completes the stepping down of AC voltage first then it converts it into DC |
It converts the input signal into DC first then it steps down the voltage up to the desired level |
|
Size and weight |
Heat sinks for high power linear regulators add size and weight. Transformer, if used are large due to low operating frequency (50 or 60 Hz) |
Smaller transformer due to higher operating frequency typically (50 kHz – 1 MH) |
|
Efficiency |
Low efficiency about 30 -65 % |
Provides higher efficiency up to 96% with modern technics |
|
complexity |
It is a simpler circuit, consists of a regulating circuit along with noise filtering capacitors. |
A more complex circuit that includes a controller IC, several transistors, diodes, transformer, etc. |
|
Noise and EMI (electromagnetic interference) |
It immune to noise and electromagnetic interference |
The effect of noise and electromagnetic is quite significant, thus the EMI filters are required. |
|
Radio interference |
No radio interference |
Radiofrequency shielding is required as switching produces more Radio interference. |
|
Reliability |
More reliable when compared to SMPS |
Its reliability depends upon transistors used for switching |
|
Transient response |
It gives a faster response |
It gives a slower response compared to the linear power supply |
|
Applications |
|
|
Hence, the transformer of the SMPS is smaller in size when compared to the transformer in the linear power supply because of its high operating frequency.
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