We can observe that in both cases, the load current direction is the same, i.e., up to down as shown in the figure – so unidirectional, which means DC current. Load current starts flowing through the D3 and D4 diodes when these diodes start conducting as shown in the figure. Circuit Operationĭuring the negative half cycle of the input AC waveform, the diodes D3 and D4 are forward biassed, and D1 and D2 are reverse biased. When the voltage, more than the threshold level of the diodes D1 and D2, starts conducting – the load current starts flowing through it, as shown in the path of the red line in the diagram below. For understanding the bridge rectifier’s working principle, we have to consider the below circuit for demonstration purposes.ĭuring the Positive half cycle of the input AC waveform diodes, D1 and D2 are forward biased and D3 and D4 are reverse biased. Bridge Rectifier OperationĪs we discussed above, a single-phase bridge rectifier consists of four diodes and this configuration is connected across the load. Suppose the microcontroller works at 5V DC, but the output after the bridge rectifier is around 16V, so to reduce this voltage, and to maintain a constant level – no matter voltage changes in the input side – a voltage regulator is necessary. The last stage of this regulated DC supply is a voltage regulator that maintains the output voltage to a constant level. This capacitor rating also depends on the output voltage. Filtering is normally performed with one or more capacitors attached across the load, as you can observe in the below figure wherein smoothing of the wave is performed. Since the output after the diode bridge rectifiers is of pulsating nature, and for producing it as a pure DC, filtering is necessary. But this circuit doesn’t need a center-tapped transformer so it resembles a low-cost rectifier. The main advantage of the bridge rectifier is that it produces almost double the output voltage as with the case of a full-wave rectifier using a center-tapped transformer. Similarly, D2 & D4 diodes will conduct electric current throughout a negative half cycle. The pairs of diodes like D1& D3 will conduct electric current throughout the positive half cycle. The arrangement of two diodes can be made in such a way that the electricity will be conducted by two diodes throughout every half cycle. Here load resistor is connected in between two terminals like C & D. Once the input signal is applied across the two terminals like A & B then the o/p DC signal can be attained across the RL. So, the size, as well as cost, will be reduced.
The main benefit of this design is the lack of an exclusive center-tapped transformer. The connection of these diodes can be done in a closed-loop pattern to convert the AC (alternating current) to DC (Direct Current) efficiently. This circuit can be designed with four diodes namely D1, D2, D3 & D4 along with a load resistor (RL). The bridge rectifier construction is shown below.