5.4: Rectifier circuits
5.4 Rectifier circuits
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Rectifier circuits are arrangements for converting alternating power to d.c. power. A transformer is usually used to change the voltage levels and to provide safety isolation between the mains supply and your circuit. The three common rectifier configurations are shown in Fig. 5.4.1. Output voltages and currents, including smoothing capacitors and a load resistor are shown in Fig. 5.4.2.
Figure 5.4.1: ( a) Half-wave rectifier. ( b) Full-wave rectifier. ( c) Full-wave bridge rectifier.
Figure 5.4.2: ( a) Waveforms for half-wave rectifier. ( b) Waveforms for full-wave bridge rectifier.
The negative values of I( Cl) simply represent current flowing in the 'opposite' direction as C l supplies the output while the rectifiers are not conducting. The PSpice plot of AVG( M( I( R2))) is the average of the modulus of the current through R 2 and this will be found to be equal to AVG( I( Rl) + I( Cl)) as it should.
The relationship between output current, ripple and smoothing capacity is usually derived from curves of the type produced by Schade (1943) and by Waidelich (1947), though it should be noted that these were originally derived for vacuum tube rectifiers which have substantial forward voltage drops. The defining parameter is the quantity ?R L C as shown...