Post on 19-Dec-2015
Diodes with RL loads. Freewheeling Assume ideal diode (zero reverse rocvery time, zero voltage drop)
An antiparallel diode known as the freewheeling diode must be connected across the load to provide a path for the inductive current to flow.
Diode rectifiers
Learn performance parameters of rectifiers and power converters
Study effects of load inductance on load current
L
R
D1
D2
Vs
From www.powerdesigners.com
The diode current is found using the Laplace transform method:
Note that the diode conduction time islonger than half-period
The waveform is nonsinusoidal but periodic.
Recommended reading
● Chapter 1● Sections 2.10-2.13 and examples in those sections, the rest are optional)● Sections 3.1 to 3.3, example 3.2
For a steady state solution, require i0(0)= i0(T)=I0. Then
I0>0 guarantees that the current flows continuously.
Conclusion● An inductive load can make load current flow
continuously if voltage ratio is below the critical value
● E=0 guarantees continuous current● If L=0, any E>0 will cause current interruptions ● References: Section 3.4 and examples in that
section
Condition for continuous load current
Largest critical value of the EMF ratio is substantially higher (95.5% vs 63.6%)