Power controller for active-inductive loads up to 15 kW. Scheme, description

Free technical library

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

Power controller for active-inductive loads up to 15 kW. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Regulators of current, voltage, power

Comments on the article

The described device can provide smooth and fast power control on an active-inductive load. It can be used in welding machines, to control lighting, to control asynchronous motors, to regulate the voltage on the primary winding of a transformer in high-voltage rectifiers or a load transformer to check and adjust the operation of the overcurrent protection of powerful electromagnetic starters, etc.

The block diagram of the power regulator is shown in Fig.1.

Power controller for active-inductive loads up to 15 kW

The controller consists of a power section (MF) and a control system (CS), which includes a phase shifter (FSU) and an input shaper (VF). The MF can only work when two back-to-back thyristors or a triac are applied to the control electrodes at certain times of the pulses that ensure that these valves are turned on. The thyristors are turned off due to a change in the polarity of the mains voltage and a decrease in the current through the valve to zero.

The moments of time at which one or the other thyristor must be switched on are set by the control signal Uy. The FSU converts the control signal into an angular interval α. The WF generates a control pulse in shape, duration and amplitude. When creating a VF, it is important to achieve high noise immunity of their operation, since high-amplitude voltage surges occur in the MF converter, which can penetrate into the control system through parasitic capacitances. It is most expedient to use the connection of the control system with the midrange through an optical channel (optocoupler).

The schematic diagram of the regulator is shown in Fig.2.

(click to enlarge)

The midrange of the regulator is made on a powerful triac VS1 and circuits L1C7, L2C8 (reactive power source with suppression of harmonic distortions on the 5th and 7th harmonics). This source is used to increase the efficiency of the device. Capacitors C7 and C8 generate reactive power Qc. The capacitance of capacitors C7 and C8 (total) is selected depending on the inductive load based on QC = Qlmax. In three-phase systems, harmonics that are multiples of the 3rd are absent due to symmetry, and the 5th, 7th, 11th, etc., are harmonic components in the network. harmonics. The lower ones are the most intense.

The resonant frequency of the circuit L1C7 ω5 = 5ω, for this circuit the relation (3С7L1)1/2 = 1/5ω is fulfilled. In the L2C8 circuit, resonance occurs at a frequency ω7 = 7ω, for this circuit (3С8L2)1/2 = 1/7ω. If C7 = 10 uF, C8 = 5 uF, then L1 = L2 = 10 mH.

VF is made on the optocoupler U1 and transistors VT3, VT4. When the control signal (log "1") arrives at the anode of the optocoupler LED, the transistor optocoupler is turned on, the transistors VT3 and VT4 close. A positive signal appears on the control electrode of a symmetrical thyristor, which puts this device in an open state.

FSU is built on a waiting multivibrator DD1, which produces pulses of a given duration, synchronized with input pulses with a frequency of 100 Hz and issued by a full-wave bridge rectifier on diodes VD1-VD4 and an amplitude limiter amplifier on a VT1 transistor. The FSO operates as follows (see the timing diagram in Fig. 3).

Power controller for active-inductive loads up to 15 kW

In the initial state, the outputs of the trigger Q=0, Qinv=1. With the positive edge of the pulse arriving at the input C, the trigger will switch, after which a new state Q=1 and Qinv=0 will come, since D=1. Capacitor C1, until then discharged, will be charged through

resistor R4, and when the voltage across it reaches the threshold value (Uc = Uthr, for CMOS chips Uthr = 0,5Upit), a new switching will occur due to the voltage at input R, as a result of which the flip-flop will return to its original state. The pulse duration at the outputs Q and Qinv can be adjusted by a variable resistor R4 τi = R4C1. Capacitor C1 is discharged through diode VD5 and open trigger output transistors.

The 27 V power supply is made on diodes VD11-VD14 and capacitors C5, C6; 9 V power supply - on diodes VD6-VD9, capacitors C2-C4, zener diode VD10 and transistor VT2.

The described power regulator can be used in a 220 V network by using the appropriate transformer T1.

Construction and details. Transformer T1 - any power 10-15 W with voltage on the secondary windings: U2 = 10 V; U3 = 12 V; U4 \u20d 4 V. Resistor R10 of any type, R1 of PEL type, the rest of MLT type. Capacitors C2, C5, C73 of type K9-73, K17-3, capacitors C4, C6, C50 of type K35-7, capacitors C8, C73 of type K2P-41, K1-1000, MBGT for a rated voltage of at least 1 V. Triac VS80 designed for direct current of at least XNUMX A. Transistors and diodes with any letter index.

The adjustment of the device is reduced to the selection of the resistor R5 so that the current through the zener diode VD10 is within 5 ... 15 mA, and the selection of the capacitor C1 so that the duration of the single vibrator pulse does not exceed 10 ms when the position of the middle contact of the resistor is in the extreme left position according to the diagram.

References:

Gorbachev G.N., Chaplygin E.E. Industrial electronics. -M.: Energoatomizdat, 1988.
Ivanov V.I., Aksenov A.I., Yushin A.M. Semiconductor optoelectronic devices. Ref. -M.: Energoatomizdat, 1988.

Author: A.N.Mankovsky

See other articles Section Regulators of current, voltage, power.

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

Swimming pools can be dangerous 03.01.2002

A group of doctors from the Catholic University of Leuven (Belgium) claims that visiting the swimming pool leads to allergies and asthma in children.

226 children aged 8 to 12 were examined. Some of them have never been in swimming pools, others have been in the pool three times a week since the age of three or four. Analyzes have shown that in children who have been swimming in the pool for a long time, proteins appear in the blood that are characteristic of adult smokers and indicate damage to lung tissue. Other researchers have found an increased prevalence of asthma in swimming pool attendants. Both phenomena are apparently explained by the presence of chlorine in the water.

Doctors believe that the chlorine added to the water for disinfection should be replaced by ozone or bromine.

Other interesting news:

▪ If aliens exist, we will know about them in the next 20 years

▪ Graffiti Wall Cleaner

▪ Fast biofuel from algae

▪ The nurses will scrub the copper

▪ Washbasin without plumbing

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Big encyclopedia for children and adults. Selection of articles

▪ article There are still judges in Berlin. Popular expression

▪ article Can a dolphin talk? Detailed answer

▪ battery electrician article. Job description

▪ article Electric planers. Encyclopedia of radio electronics and electrical engineering

▪ article Refinement of the CB transceiver MAYCOM EM-27D. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

Comments on the article:

Nicholas
In this circuit, the triac will open only in positive half-cycles. Either a negative voltage or a voltage coinciding with the anode voltage is applied to the control electrode of the triac (pin 2).

Eugene
Not bad.

All languages of this page

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