In this note, we are going to know about Three Phase Full Wave Controlled Rectifier with R Load and about its circuit diagram, working principle, applications as well. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.
Author Name: Arun Paul.
What is Three Phase Full Wave Controlled Rectifier with R Load?
A Three Phase Full Wave Controlled Rectifier with R Load is an advanced power electronics circuit that converts a three-phase alternating current (AC) voltage into a controlled direct current (DC) output. It is commonly used in applications that demand controlled DC power. This rectifier uses six thyristors (also known as Silicon Controlled Rectifiers or SCRs) in a bridge configuration to correct the three-phase AC input.
Features of Three Phase Full Wave Controlled Rectifier with R Load
Here are the key features of three phase full wave controlled rectifier with R load –
- The circuit is powered by three phase alternating current (AC), which provides smoother operation and higher power efficiency than single-phase systems.
- The six SCRs are connected in a full-wave bridge, allowing the rectifier to convert both the positive and negative half cycles of the AC input to DC power.
- The load connected to the output is fully resistive, therefore the current through it is proportional to the applied DC voltage. The voltage and current waveforms are easier to study in this setup because the load does not introduce reactive components like inductance or capacitance.
- This rectifier controls the output DC voltage by altering the firing angle (α) of SCRs. The firing angle determines when each SCR conducts throughout the AC input cycle, which affects the amount of voltage transmitted to the load.
Circuit Diagram of Three Phase Full Wave Controlled Rectifier with R Load
This is the circuit diagram of three phase full wave controlled rectifier with R load –
- Three Phase AC Source: The circuit is powered by a three-phase alternating current source with three phases: R, Y, and B. Each phase produces a sinusoidal AC voltage.
- Thyristors or SCRs: The circuit contains six thyristors (SCRs), with two SCRs connected in parallel for each phase. These SCRs are programmed to conduct at certain periods during the AC cycle in order to allow rectification.
- Firing Control: The firing angle of the SCRs is set to regulate the output voltage. The firing angle determines when the SCRs begin conducting during the AC cycle. Adjusting this angle allows you to alter the average DC output voltage.
- Resistive Load or R Load: The rectified DC voltage is applied to a totally resistive load, therefore the current through the load is directly proportional to the applied voltage. The load does not contain any inductive or capacitive components.
- Output DC Voltage: The rectifier’s output is a pulsing DC voltage with ripples caused by the SCRs’ alternating conduction. There are six pulses every cycle, so the ripple frequency is six times the input AC frequency.
Operation of Three Phase Full Wave Controlled Rectifier with R Load
In a three-phase full-wave controlled rectifier, each SCR or Silicon Controlled Rectifier operates for a portion of the AC input cycle. Each half-cycle of the AC voltage activates two SCRs, one from each phase of the three-phase input. The firing angle dictates when the SCRs turn on, which influences the length of their conduction time.
Delaying the firing of the SCRs (raising the firing angle) lowers the average DC output voltage. In contrast, a narrower firing angle produces a greater DC output voltage. The ability to alter the firing angle enables for exact control of the output voltage, making the rectifier suited for applications such as motor drives, power supply, and battery charging systems.
Applications of 3 Phase Full Wave Controlled Rectifier with R Load
Here we have listed some applications of three phase full wave controlled rectifier with R load –
- It has the ability to control the DC output voltage allows for precise speed control of DC motors.
- The rectifier generates a controlled DC voltage that charges batteries effectively.
- Used in industrial and commercial power supply that demand a precise DC voltage.