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Difference between Centre-Tapped Rectifier and Bridge Rectifier
The electronic circuit which is used to convert alternating current (AC) into direct current (DC) is known as a rectifier. The process of converting the alternating current into direct current is called rectification. The main component of the rectifier which performs the rectification is the semiconductor diode.
Depending upon the type of conversion from AC to DC, i.e. half cycle of AC or full cycle of AC, rectifiers can be grouped into two categories −
- Half-wave rectifier
- Full-wave rectifier
Based on the circuit configuration, the full-wave rectifier is further classified into two types viz. −
- Centre-tapped full-wave rectifier
- Bridge rectifier
Thus, both centre-tapped and bridge rectifiers are types of full-wave rectifier, i.e. they convert the full cycle of AC into DC. However, there are many differences between centre-tapped and bridge rectifier which are discussed in this article in the tabular form. Also, we have added a brief description of both centre tapped rectifier and bridge rectifier for your reference.
What is a Centre-Tapped Rectifier?
When the full-wave rectifier circuit is designed by using two semiconductor diodes, a centre-tapped transformer and a load resistor, then the rectifier circuit is known as centre-tapped full-wave rectifier.
In the centre tapped rectifier, the anodes of the diodes are connected to the outer terminals of secondary winding of the centre-tapped transformer and the cathodes are connected together to a common point. The load resistor is connected between the centre tapping point of the transformer and the common point. The circuit diagram and the output waveform of a centre tapped rectifier is shown in Figure-1.
During the positive half cycle of AC, the diode D1 conducts and converts the positive half cycle of AC into DC, while during the negative half cycle, the diode D2 conducts and converts the negative half cycle of AC into DC. In this way, the complete cycle of AC is converted into pulsating DC whose waveform is shown in Figure-1. The DC output is received across the load resistor.
What is a Bridge Rectifier?
The bridge rectifier is also a full-wave rectifier which converts full cycle of AC into DC. The circuit of a bridge rectifier consists of four diodes which are arranged in the form of a Wheatstone bridge as shown in Figure-2.
When an alternating current is applied to the bridge rectifier, it converts it into pulsating direct current. The conversion of AC into DC is performed as: during the positive half cycle, the diodes D1 and D3 are forward biased whereas the diodes D2 and D4 are reverse biased. Thus, the current flows from terminal A to terminal B through the load resistor. While, during the negative half cycle of AC, only diodes D2 and D4 conducts, thus the output current again flows from terminal A to terminal B. Hence, we get a unidirectional current (direct current) at the output.
The main advantage of the bridge rectifier over the centre tapping rectifier is that there is no need of centre tapped transformer in case of the bridge rectifier.
Difference between Centre-Tapped Rectifier and Bridge Rectifier
The key differences between centre-tapped and bridge rectifier are highlighted in the following table −
| Basis of Difference | Centre-Tapped Rectifier | Bridge Rectifier |
|---|---|---|
| Definition | A full-wave rectifier which has two semiconductor diodes and a centre tapped transformer in its circuit is known as centre-tapped rectifier. | A full-wave rectifier which has four semiconductor diodes that are arranged in a Wheatstone bridge fashion is known as bridge rectifier. |
| Number of diode | Centre tapped rectifier requires only two diodes. | Four diodes are required to design the circuit of bridge rectifier. |
| Circuit complexity | The circuit of a centre-tapped rectifier is less complicated. | The circuit of a bridge rectifier is more complex than that of the centre tapped rectifier. |
| Need of transformer | In case of centre tapped rectifier, the transformer is mandatory for providing centre tapping in the secondary winding. | It is not necessary to provide a transformer in the bridge rectifier circuit. |
| Rating of transformer | The transformer required in the centre tapped rectifier is larger in kVA rating. | The kVA rating of transformer used in a bridge rectifier is smaller than that of a centre-tapped rectifier. |
| Voltage drop across the diodes | As only two diodes are used in the centre tapped rectifier, thus the voltage drop across the diodes is less. | The voltage drop across the diodes is high because the bridge rectifier consists of four diodes. |
| Voltage regulation | The voltage regulation of the centre tapped rectifier is better. | The bridge rectifier has good voltage regulation. |
| Peak inverse voltage (PIV) | The peak inverse voltage of diode in the centre tapped rectifier is double of the maximum voltage across secondary winding of the transformer, i.e., $$\mathrm{PIV\:=\:2\mathit{V}_{smax}}$$ | The peak inverse voltage of diode is equal to the maximum voltage across the secondary winding of the transformer, i.e., $$\mathrm{PIV\:=\:\mathit{V}_{smax}}$$ |
| Economic efficiency | The centre tapped rectifier is more efficient economically because it requires only two diodes. | The bridge rectifier is economically less efficient as it requires four diodes. |
| Transformer utilization factor (TUF) | The transformer utilization factor of centre-tapped rectifier is equal to 0.692. | The transformer utilization factor of bridge rectifier is equal to 0.8106. |
| Diode forward resistance | In case of centre tapped rectifier only one diode is forward biased at a time, thus, the diode forward resistance is equal to forward resistance of one diode, i.e. RF. | There are two diode forward biased at a time in the bridge rectifier, thus the diode forward resistance is equal to 2RF. |
Conclusion
Centre-tapped and bridge rectifiers are both types of full-wave rectifiers, i.e., both of these convert full cycle of AC into DC. But, their circuit configuration and working is different. Some important differences between centre-tapped rectifier and bridge rectifier are discussed in the above table. The most significant difference between a bridge rectifier and a centre-tapped rectifier is that a bridge rectifier requires four diodes in its circuit, while a centre-tapped rectifier requires only two diodes.
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