Powerful laboratory power supply with increased efficiency. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Powerful laboratory power supply with increased efficiency. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Power Supplies

Comments on the article

The adjustable power supply is an integral part of the amateur radio laboratory. The magazine "Radio" described many such devices, but some of them have low efficiency. The fact is that most often laboratory power supplies are made on the basis of linear stabilizers, since it is often very difficult to eliminate the main drawback of pulsed sources - an increased level of ripple. As a rule, a consequence of such a circuit solution is increased power losses. The author proposes his own solution to this problem.

You can increase the efficiency of the stabilizer by making it two-stage: the first stage is a pulse preliminary stabilizer; the second - the usual linear. Both stages are covered by feedback, thanks to which the minimum allowable voltage drop is maintained on the linear stabilizer and, thereby, high efficiency is ensured.

Switching stabilizers, assembled on a modern element base [1, 2], provide high operational parameters, including low losses. These devices were taken as a basis for the development of the proposed laboratory power supply.

Main Specifications

Input voltage, V......43
Output voltage interval, V......0...35
Maximum load current, A ...... 7,5
Switching stabilizer conversion frequency, kHz......55

The scheme of the device is shown in fig. 1. The switching regulator of the first stage is assembled on the TL598 (DA4) SHI controller chip from Texas Instruments, which controls the IRF9540 (VT3) switching transistor. The TL598 microcircuit differs from the common TL494 by the presence of a push-pull amplifier at the output (the closest domestic SHI controller in terms of characteristics is KR1114EU4). The use of this particular microcircuit is due to its high technical parameters: output current up to 0,2 A, clock frequency up to 300 kHz, as well as a small price.

(click to enlarge)

The use of a switching field-effect transistor IRF9540 (VT3) and a Schottky diode KD2998G (VD2) with a low voltage drop and recovery time made it possible to increase the efficiency of the switching regulator up to about 90%. To increase the limits of output voltage regulation, the buffer amplifier on the VT2 transistor assembly is powered by an auxiliary stabilizer on the DA2 chip. A parametric voltage regulator based on a field-effect transistor VT4 and a zener diode VD9 improves the stabilization coefficient and allows you to work at a higher input voltage. Resistor R9 in the circuit of the filter capacitor C8 protects the DA2 chip from overload when the device is turned on.

From the output of the switching regulator, the voltage is supplied to a linear regulator assembled on a DA1 chip with a low voltage drop. With this circuit design, the output characteristics of the laboratory unit are determined by the parameters of the microcircuit, which provides good ripple suppression, current protection and overheating, and the power loss on it is approximately equal to 5%.

In order to regulate the output voltage of the unit from zero, a voltage of -1 V is supplied to the control output circuit of the DA15 microcircuit from a separate source.

Transistor optocoupler U1 maintains a voltage drop across the linear regulator of about 1,5 V. If the voltage drop across the chip increases (for example, due to an increase in input voltage), the emitting diode of the optocoupler and, accordingly, the phototransistor turns on. The SHI controller turns off by closing the switching transistor. The voltage at the input of the linear regulator will decrease.

To improve stability, the resistor R3 is placed as close as possible to the stabilizer chip DA1.

Inductors L1, L2 - pieces of ferrite tubes put on the terminals of the gates of field-effect transistors VT1, VT3. The length of these tubes is approximately half the length of the output.

Powerful laboratory power supply with increased efficiency

The inductor L3 is wound on two annular magnetic cores K36x25x7,5 folded together from permalloy MP140. Its winding contains 45 turns, which are wound into two PEV-2 wires with a diameter of 1 mm, laid evenly along the perimeter of the magnetic circuit.

Since at a load current close to the maximum, significant power is released on the DA1 stabilizer and the VT3 transistor, they should be installed on heat sinks with an area of at least 30 cm2. It is permissible to replace the IRF9540 (VT3) transistor with IRF4905, and the IRF1010N (VT1) transistor with BUZ11, IRF540, KP727B.

The area of heat sinks is calculated according to the method described in [3].

If you need a unit with an output current greater than 7,5 A, you must add another regulator DA5 in parallel with DA1 (Fig. 2). Then the maximum load current will reach 15 A. In this case, the L3 inductor is wound with a bundle consisting of four PEV-2 wires with a diameter of 1 mm, and the capacitance of capacitors C1-C3 is approximately doubled. Resistors R18, R19 are selected according to the same degree of heating of microcircuits DA1, DA5. The SHI controller should be replaced with another one that allows operation at a higher frequency, for example, KR1156EU2.

If there is no need for a large load current, the KR142EN22A stabilizer can be replaced with KR142EN22 (maximum current 5 A) or KR142EN12A (1,5A).

Literature

Mironov A. Switching voltage stabilizer with increased efficiency. - Radio, 2000, No. 11, p. 44, 45.
Mironov A. Application of synchronous rectifiers in pulse voltage stabilizers. - Radio, 2001, No. 10, p. 38, 39.
Semenov B.Yu. Power electronics for amateurs and professionals. - M.: Solon-R 2001, p. 115-121

Author: S.Korenev, Krasnoyarsk

See other articles Section Power Supplies.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive

Creation of an artificial uterus 27.08.2016

The first 13 days after human conception are still largely a mystery to scientists, as the process is almost impossible to observe. But now scientists have created the world's first artificial womb, or at least a prototype.

We cannot look into the uterus, we cannot see how fertilized eggs grow, so we understand the whole process only in general terms. However, researchers at the Rockefeller Center were the first to be able to observe and grow human embryos for 13 days in a fully laboratory environment (more observation of egg growth is prohibited by law for ethical reasons). Scientists raised the embryos with insulin and other nutrients outside of the usual conditions. The experiment demonstrated that the embryo itself contains a set of genetic instructions responsible for development, which is not associated with the mother (at least at the initial stage)

This research provides an opportunity to develop new models of human growth, and may also help in cases of miscarriage and infertility. Of course, this does not mean that in the future all children will be raised in a laboratory, but it is quite possible that the human uterus will be just one of the options.

Other interesting news:

▪ Cosmic ray clock synchronization

▪ The origin of the hollow in the tree

▪ Smartphone as thick as a credit card

▪ Wireless charging via Wi-Fi

▪ When the ears wither

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Low frequency amplifiers. Article selection

▪ article Piano in the bushes. Popular expression

▪ article How big is the density of an atomic nucleus? Detailed answer

▪ article Luk-Tatar. Legends, cultivation, methods of application

▪ article USB thermometer on a microcontroller. Encyclopedia of radio electronics and electrical engineering

▪ article A semi-permeable partition retains sugar and allows water to pass through. Chemical Experience

Leave your comment on this article:

Comments on the article:

Sergei
Assemble a pulse voltage conversion circuit in order to put a linear stub at the output. voltage on one, by the way, not a cheap microcircuit? This is really a strange decision... Wouldn't it be easier to put a pair of LC filters at the output to suppress ripples? Does it make sense to assemble an impulse conversion circuit at all, if the output is still KR142EN22A? Has anyone replicated this pattern?

Maxim Saranchin
I tried to make this PSU at the time. Earned with alteration of the control of the transistor VT3. It was not possible to start with the original scheme (this node is not working). The author himself apparently did not try. Well, yes, the linear stabilizer is a little warm, say at 10v and 8A.

All languages of this page

Home page | Library | Articles | Website map | Site Reviews