Contents
What is the use of coupling inductor?
Purpose-designed coupled inductors are used in a variety of power conversion circuits such as flyback, SEPIC, Fly-Buck™, Cuk, ZETA and multi-phase topologies. These voltage regulation circuits use coupled inductors to efficiently provide the required output voltages, which may be stepped up or down from the input.
Can you combine inductors?
Just like resistors or capacitors, you can combine inductors in series or parallel within an electronic circuit. Series inductors: Just add up the value of each individual inductor. Two or more identical parallel inductors: Add them up and divide by the number of inductors.
How are coupled inductors used in a buck converter?
Figure 2. Normalized current ripple for a 4-phase buck converter: discrete 210nH and coupled 50nH inductors with different coupling coefficient Lm/L. Figure 1 illustrates the dramatic current-ripple cancellation in all the power circuitry due to the coupled inductors.
Which is better a discrete or coupled inductor?
To better appreciate the coupled inductor size, notice that discrete inductors (ones that are much more physically narrow) can be considered for this 4-phase solution, However, such inductors would either decrease the saturation rating or need a value smaller than the targeted 210nH.
What is the coupling coefficient of a coupled inductor?
Normalized current ripple for a 4-phase buck converter: discrete 210nH and coupled 210nH inductors with different coupling coefficient Lm/L. Figure 2. Normalized current ripple for a 4-phase buck converter: discrete 210nH and coupled 50nH inductors with different coupling coefficient Lm/L.
How is the ripple in a discrete inductor normalized?
The current ripple is normalized by a maximum current ripple: ripple in the discrete inductor at D = 0.5 (so the normalized current ripple in a discrete inductor is 1 at D = 0.5). A typical application of 12V to 1.8V relates to the D = 0.15, as marked on the plot.