Rectifiers are devices used to convert AC voltage into DC or direct current. There are two main types of rectifiers. one is an uncontrolled rectifier and another is a controlled rectifier.

Uncontrolled rectifier

An uncontrolled rectifier is a type of rectifier circuit that does not use any external control elements to regulate the output voltage or current. Instead, the output of an uncontrolled rectifier is determined by the input voltage and the characteristics of the rectifying element (e.g., a diode).

There are several types of uncontrolled rectifiers, including, important of them are as under

Half-wave rectifier

A half-wave rectifier is a type of uncontrolled rectifier that only utilizes one half of the AC waveform. It consists of a single diode connected in series with the load. The output of a half wave rectifier is a pulsating DC voltage that is less than the peak of the AC waveform.

Full wave rectifier

As mentioned earlier, a full wave rectifier is a type of uncontrolled rectifier that converts an AC input into a DC output. There are two common configurations for full wave rectifiers: the bridge rectifier and the center tap rectifier. Both of these configurations utilize both halves of the AC waveform, resulting in a DC output that is close to the peak of the AC waveform.

Voltage multiplier

A voltage multiplier is a type of uncontrolled rectifier that is used to create a DC voltage that is higher than the peak of the AC waveform. There are several types of voltage multipliers, including the diode-capacitor voltage multiplier (also known as a “charge pump”) and the diode-resistor voltage multiplier.

Split-phase rectifier

A split-phase rectifier is a type of uncontrolled rectifier that is used in power supplies for low-power AC loads. It consists of two half wave rectifiers that are connected in parallel and out of phase with each other. The output of a split-phase rectifier is a pulsating DC voltage with a lower ripple content compared to a single half wave rectifier.

Selenium rectifier

A selenium rectifier is a type of uncontrolled rectifier that uses a layer of selenium on a metallic backing as the rectifying element. Selenium rectifiers were commonly used in the early days of electronic power supplies, but have been largely replaced by more efficient and reliable rectifier technologies.

Vacuum tube rectifier

A vacuum tube rectifier is a type of uncontrolled rectifier that uses a vacuum tube (also known as a “valve”) as the rectifying element. Vacuum tube rectifiers were commonly used in electronic power supplies before the development of solid state rectifiers (e.g., diodes).

Precision rectifiers

A precision rectifier is a type of rectifier circuit that is designed to have a very low voltage drop across the rectifying element (e.g., a diode). This results in a higher output voltage and accuracy than an uncontrolled rectifier. Precision rectifiers are often used in applications where a high level of accuracy is required, such as in instrumentation and measurement systems where DC equivalent voltage is required for measurement or as a voltage reference. The precision rectifier is often made with an operation amplifier and diode combination. Precision rectifiers can not be used as a DC power sources.

Ideal rectifiers:

An ideal rectifier is a theoretical concept that represents the ideal performance of a rectifier circuit. In an ideal rectifier, the output voltage is equal to the peak of the AC waveform and there is no voltage drop across the rectifying element. In reality, it is not possible to achieve an ideal rectifier due to the inherent voltage drop across the rectifying element and other losses in the circuit. However, the concept of an ideal rectifier is useful for analyzing and comparing the performance of different rectifier circuits.

high frequency rectifiers

High frequency rectifiers are specialized electronic devices used to convert high frequency alternating current (AC) into direct current (DC). They are used in a wide range of applications, including power supplies, radio and television transmitters, and high-speed electronic devices.

Schottky diode rectifier

A Schottky diode rectifier uses a Schottky diode as the rectifying element. Schottky diodes have a lower forward voltage drop and faster switching speed compared to standard diodes, making them well-suited for use in high frequency rectifiers.

PIN diode rectifier

A PIN diode rectifier uses a PIN diode as the rectifying element. PIN diodes have a low capacitance and can operate at high frequencies, making them well-suited for use in high frequency rectifiers.

GaAs diode rectifier

A GaAs diode rectifier uses a GaAs (gallium arsenide) diode as the rectifying element. GaAs diodes have a fast switching speed and low forward voltage drop, making them well-suited for use in high frequency rectifiers.

Transistor-based rectifiers

Transistor-based rectifiers use one or more transistors as the rectifying element. These rectifiers are often used in high frequency switching circuits and can provide faster switching speeds compared to diode-based rectifiers.

LCD (Inductor-Capacitor-Diode) rectifiers

LC rectifiers use an inductor and a capacitor in combination with a diode to rectify the input signal. These rectifiers are often used in high frequency RF circuits and can provide good harmonic rejection and high voltage gain.

Active rectifiers

Active rectifiers use one or more active devices (e.g., operational amplifiers) in combination with a diode to rectify the input signal. These rectifiers can provide high accuracy and good linearity but may have lower efficiency compared to other types of high frequency rectifiers. High frequency RMS converters and op-amp based amplitude demodulation is an examples of an active rectifier.

Controlled Rectifier

A controlled rectifier is a type of electronic circuit that uses semiconductor devices to convert AC power to DC power. It is also known as a thyristor circuit, as it typically uses thyristors (a type of semiconductor device) to control the flow of current. The key feature of a controlled rectifier is that the flow of current can be controlled by varying the control signal applied to the thyristors. This allows for precise control over the output voltage and current, making it useful in a variety of applications such as power supplies, motor drives, and heating controls.

Types of Controlled Rectifiers

A rectifier is an electrical device that converts alternating current (AC) to direct current (DC). A controlled rectifier is a type of rectifier that can be turned on and off, allowing the control of the DC output. There are several types of controlled rectifiers, each with its own characteristics and applications. Here, we will discuss the four most common types:

Silicon Controlled Rectifier (SCR):

A silicon controlled rectifier (SCR) is a type of controlled rectifier that uses a silicon-based thyristor as the main switching element. The SCR is a three-layer, four-terminal device with a gate terminal that controls the flow of current through the device. The SCR can be triggered into conduction by a positive pulse applied to the gate terminal, allowing current to flow through the device. Once triggered, the SCR will remain in the on state until the current flowing through it drops below a certain level, known as the “holding current.” This allows the SCR to act as a switch that can be turned on and off by controlling the gate terminal. SCR’s are used in a variety of applications such as power supplies, motor control, and heating control because of their ability to handle high current and voltage levels.

Gate Turn-Off Thyristor Controlled Rectifier (GTO):

A Gate Turn-Off thyristor (GTO) is a type of controlled rectifier that uses a thyristor with a built-in gate circuit that can turn off the device. A GTO is similar to a standard thyristor, but it has an additional gate terminal that can be used to turn the device off. It is a type of power electronic switch that can handle high voltage and current and can be used in applications such as power supplies, motor drives, and inverters. It is also known as a turn-off thyristor because it can be turned off by applying a negative voltage to the gate terminal. This allows for more precise control over the output voltage and current compared to traditional thyristors, which can only be turned on. GTO’s are used in a variety of industrial applications such as power supplies, motor control, and heating control, where high-voltage and high-current switching is required.

Insulated Gate Bipolar Transistor Controlled Rectifier (IGBT):

An Insulated Gate Bipolar Transistor (IGBT) is a type of power electronic switch that can be used in a controlled rectifier circuit. It is a three-layer, four-terminal device that combines the properties of a bipolar junction transistor (BJT) and a metal-oxide-semiconductor field-effect transistor (MOSFET) to create a high-performance switching device. An IGBT controlled rectifier is a type of circuit that converts AC power to DC power by using IGBT as the main switching element. The IGBT can be controlled by a voltage applied to its gate terminal, allowing for precise control of the output voltage and current. IGBT’s are widely used in a variety of industrial applications such as motor drives, variable speed drives, power supplies and welding equipment because of their high switching speed, high efficiency and ability to handle high power.

Single Phase and Poly phase controlled rectifier

Single-phase controlled rectifier is a type of circuit that converts single-phase AC power to DC power. It typically uses semiconductor devices such as thyristors or IGBTs as the main switching element to control the flow of current. Single-phase controlled rectifiers are used in a variety of applications such as power supplies, motor drives, and heating controls.

On the other hand, a poly-phase controlled rectifier is a type of circuit that converts multi-phase AC power to DC power. It typically uses semiconductor devices such as thyristors or IGBTs as the main switching element to control the flow of current. Poly-phase controlled rectifiers are used in a variety of industrial applications such as motor drives, variable speed drives, and power supplies.

One of the main differences between single-phase and poly-phase controlled rectifiers is the number of input phases. Single-phase rectifiers have only one input phase, while poly-phase rectifiers have multiple input phases. This makes poly-phase rectifiers more efficient and powerful than single-phase rectifiers, as they can handle more complex loads and provide more precise control over the output voltage and current.

Another important difference is that single phase rectifiers are used in small and medium power electronic applications while poly phase rectifiers are used in high power electronic applications, such as large motor drives, large inverters, large UPS systems, and high voltage DC transmission systems,etc.