Smoothing rectified circuits

Another popular rectifier circuit is the full-controlled three-phase full wave rectifier. This circuit is more expensive because six thyristors are used. However, the form factor is much better, about 1.01, and the ripple current is 360 Hz. The higher frequency makes it easier to filter the ripple current. The half-controlled three-phase bridge rectifier circuit may require armature current smoothing reactors to reduce the ripple current. Another problem associated with the non-uniform DC input to the motor is the commutation. The motor must commutate under a relatively high degree of leakage reactance. 

Rectification — is defined as the conversion of -> alternating current, AC, into pulsating -> direct current, DC, by any means other than the use of a motor-generator. That is, the AC is primarily converted by use of a -> rectifier into (unfiltered) unidirectional half-cycles. The percentage ratio of the DC output voltage to the peak AC input voltage of a certain rectifier device is called rectification efficiency. A circuit containing parallel -> capacitance, sometimes in combination with series inductance, is afterwards frequently applied as rectification filter in order to smooth the ripple in the DC current output. A combined device of rectifier and filter is called rectifier-filter system. 

The terminal voltage of the main generator is measured by the use of a voltage transformer connected across two of the stator lines, e.g. LI and L2. The signal is then rectified and smoothed in the automatic voltage regulator (AVR), by a circuit that incurs a small time constant Tr. ... 

In the switched-mode technique, the mains power signal is rectified and smoothed it is then switched as rectangular pulses at a frequency of 25 kHz into a ferrite transformer to obtain the desired voltage finally, it is rectified and smoothed to provide the required power to the instrument. The combination of modem transistor switching circuits with... 

Incoming three-phase AC power is rectified and smoothed to generate a variable voltage DC supply. This DC voltage is then switched among the three output phases to generate a step waveform that approximates a sinusoidal waveform. The switching is done by six SCRs (silicon-controlled rectifiers), which are sequentially fired at the proper frequency by a solid-state circuit. 

Figure 3.118 shows an d.c. supply which has been rectified, smoothed and stabilized. You could build and test this circuit at college if your lecturers agree. 

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