ArticleslgStudy

science

Voltage controller

Voltage controller is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Voltage controller rather than just read about it. In short: A voltage controller, also called an AC voltage controller or AC regulator is an electronic module based on either thyristors, triodes for alternating current, silicon-controlled rectifiers or insulated-gate bipolar transistors, which converts a fixed voltage, fixed frequency alternating current (AC) electrical input supply to obtain variable voltage in output delivered to a resistive load. This varied voltage outpu…

Voltage controller — main illustration
Voltage controller — illustration

Key takeaways

  • Voltage controller belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Voltage controller to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Voltage controller from memory before moving on to harder problems.

Reference excerpt

A voltage controller, also called an AC voltage controller or AC regulator is an electronic module based on either thyristors, triodes for alternating current, silicon-controlled rectifiers or insulated-gate bipolar transistors, which converts a fixed voltage, fixed frequency alternating current (AC) electrical input supply to obtain variable voltage in output delivered to a resistive load. This varied voltage output is used for dimming street lights, varying heating temperatures in homes or industry, speed control of fans and winding machines and many other applications, in a similar fashion to an autotransformer. Voltage controller modules come under the purview of power electronics. Because they are low-maintenance and very efficient, voltage controllers have largely replaced such modules as magnetic amplifiers and saturable reactors in industrial use.

Modes of operation Electronic voltage controllers work in two different ways; either through "on-and-off control" or through "phase control".

On-and-off control In an on-and-off controller, thyristors are used to switch on the circuits for a few cycles of voltage and off for certain cycles, thus altering the total RMS voltage value of the output and acting as a high speed AC switch. The rapid switching results in high frequency distortion artifacts which can cause a rise in temperature, and may lead to interference in nearby electronics. Such designs are not practical except in low power applications.

Phase angle control In phase angle control, thyristors are used to selectively pass only a part of each AC cycle through to the load. By controlling the phase angle or trigger angle, the output RMS voltage of the load can be varied. The thyristor is turned on for every half-cycle and switched off for each remaining half-cycle. The phase angle is the position at which the thyristor is switched on.

Applications

Light dimming circuits Temperature control of electrical heating systems Speed control of motors AC magnet controls

See also

Dimmer Motor soft starter DC injection braking Space Vector Modulation Variable-speed air compressor Vector control (motor) Motor controller Adjustable-speed drive Electronic speed control Variable-frequency drive Thyristor drive DC motor starter section of Electric motor

References

Illustrations

Voltage controller: A Voltage controller thyristor based dimmer rack
A Voltage controller thyristor based dimmer rack
Voltage controller: An electrical schematic for a typical SCR-based light dimmer
An electrical schematic for a typical SCR-based light dimmer
Voltage controller: An example of phase angle control. Blue represents the actual supply voltage of 120 V and red represents the switching on and off of the thyristor to get a controlled voltage of 60 V, achieved by cutting off the supply at certain angles and switching it on at the phase angle.
An example of phase angle control. Blue represents the actual supply voltage of 120 V and red represents the switching on and off of the thyristor to get a controlled voltage of 60 V, achieved by cutting off the supply at certain angles and switching it on at the phase angle.
Voltage controller: An example of a Voltage controller with heat sink attached in left. Min and max settings in the front
An example of a Voltage controller with heat sink attached in left. Min and max settings in the front

Worked examples

Example 1 — a first encounter with Voltage controller

Start with the simplest possible case. Write down what Voltage controller claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Voltage controller before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Voltage controller ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Voltage controller

In research
Voltage controller appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Voltage controller in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Voltage controller is common in secondary-school and first-year university syllabi. It links to neighbouring topics Power electronics, so understanding it makes those chapters shorter.
In everyday life
Look for Voltage controller outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Voltage controller in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Voltage controller means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Voltage controller out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Voltage controller in simple terms?

A voltage controller, also called an AC voltage controller or AC regulator is an electronic module based on either thyristors, triodes for alternating current, silicon-controlled rectifiers or insulated-gate bipolar transistors, which converts a fixed voltage, fixed frequency alternating current (A…

Why does Voltage controller matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Voltage controller?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Voltage controller.

Tags

  • Power electronics

Keep exploring