The device with electronic control of the charging current is made on the basis of a thyristor phase-pulse power controller. It does not contain rare radio components, with obviously working parts it does not require adjustment. The charger allows you to charge the battery with a current of 0 to 10 amperes, and can also serve as an adjustable power source for a powerful low-voltage soldering iron, vulcanizer, portable lamp and just a power supply for all occasions.
Charging current is close to pulsed in shape, which is believed to help prolong battery life.
The device is operable at ambient temperature from - 35 C to + 35 C.
The charger is a thyristor power regulator with phase-pulse control, fed from the winding II of the step-down transformer T1 through the diode bridge VDI ... VD4.
All radio components of the device are domestic, but it is possible to replace them with similar foreign ones.
Capacitor C2 - K73-11, with a capacity of 0.47 to 1 μF, or K73-16, K73-17, K42U-2, MBGP.
We will replace the KT361A transistor with KT361B - KT361Yo, KT3107L, KT502V, KT502G, KT501Zh - KT50IK, and KT315L - with KT315B + KT315D KT312B, KT3102L, KT503V + KT503G, P307. Instead of KD105B, diodes KD105V, KD105G or D226 with any letter index are suitable.
Variable resistor R1 - SP-1, SPZ-30a or SPO-1.
Ammeter RA1 - any direct current with a scale of 10 amperes. It can be made independently from any milliammeter by selecting a shunt using a standard ammeter.
The F1 fuse is fusible, but it is also convenient to use a 10 ampere automatic circuit breaker or an automobile bimetallic one for the same current.
Diodes VD1 ... VP4 can be any for a direct current of 10 amperes and a reverse voltage of at least 50 volts (series D242, D243, D245, KD203, KD210, KD213).
The rectifier diodes and thyristor are placed on aluminum radiators with a cooling area of 120 sq.cm. To improve the thermal contact of devices with radiators, be sure to lubricate the heat-conducting pastes.
Thyristor KU202V will be replaced by KU202G - KU202E; It has been verified in practice that the device operates normally with more powerful thyristors T-160, T-250.
The device uses a ready-made network step-down transformer of the appropriate power with a secondary winding voltage of 18 to 22 volts.
If the voltage on the secondary winding of the transformer is higher than 18 volts, it is advisable to replace the resistor R5 with another one of the highest resistance (for example, at 24 - 26 volts, the resistance of the resistor should be increased to 200 ohms, respectively).
In the case when the secondary winding of the transformer has a tap from the middle, or there are two uniform windings and the voltage of each is within the specified limits, then it is better to make the rectifier according to the usual full-wave circuit on 2 diodes.
With a secondary winding voltage of 28 x 36 volts, you can completely abandon the rectifier - the thyristor VS1 will simultaneously play its role (rectification is half-wave). For such a variant of the power supply, it is necessary to connect a separating diode KD105B or D226 with any letter index (cathode to resistor R5) between the resistor R5 and the positive wire. The choice of a thyristor in such a circuit will become limited - only those that allow operation under reverse voltage are suitable (for example, KU202E).
For the described device, a unified transformer TN-61 is suitable. 3 of its secondary windings must be connected in series, while they are capable of delivering current up to 8 amperes.
Consider the operation of the circuit (Fig. 1) in the first mode. An alternating voltage of 220 V is supplied to the step-down transformer Tr1. In the secondary winding, two voltages of 24V are formed relative to the midpoint. It was possible to find a transformer with a midpoint in the secondary winding, which makes it possible to reduce the number of diodes in rectifiers, create a power reserve and facilitate thermal conditions. AC voltage from the secondary winding of the transformer is supplied to the rectifier on diodes D6, D7. Plus from the middle point of the transformer goes to the resistor R8, which limits the current of the zener diode D1. Zener diode D1 determines the operating voltage of the circuit. On transistors T1 and T2, a thyristor control generator is assembled. Capacitor C1 is infected in the circuit: plus power supply, variable resistor R3, R1, C1, minus. The charge rate of the capacitor C1 is regulated by a variable resistor R3. Capacitor C1 is discharged along the circuit: emitter - collector T1, base - emitter T2, R4 min capacitor. Transistors T1 and T2 open and a positive pulse from the emitter T2 through the limiting resistor R7 and decoupling diodes D4 - D5 is fed to the control electrodes of the thyristors. In this case, the switch VK 1 is on, VK 2 is off. Thyristors, depending on the negative phase of the alternating voltage, open in turn, and the minus of each half-cycle goes to the minus of the battery. Plus from the middle point of the transformer through the ammeter to the plus of the battery. Resistors R5 and R6 determine the mode of operation of transistors T1-2. R4 is the load of the emitter T2, on which a positive control pulse is emitted. R2 - for more stable operation of the circuit (in some cases it can be neglected).
The operation of the memory circuit in the second mode (Vk1 - off; Vk2 - on). Turned off Vk1 breaks the control circuit of the thyristor D3, while it remains permanently closed. In operation, one thyristor D2 remains, which rectifies only one half-cycle and produces a charge pulse during one half-cycle. During the idle second half-cycle, the battery is discharged through the switched on Vk2. The load is an incandescent light bulb 24V x 24 W or 26V x 24W (with a voltage of 12V on it, it consumes a current of 0.5 A). The light bulb is brought outside the body so as not to heat the structure. The value of the charging current is set by the regulator R3 on the ammeter. Given that when charging the battery, part of the current flows through the load L1 (10%). Then the ammeter readings should correspond to 1.8A (for a pulsed charging current of 5A). since the ammeter has inertia and shows the average value of the current over a period of time, and the charge is made during half the period.
Details and design of the memory. Any transformer with a power of at least 150 W and a voltage in the secondary winding of 22 - 25 V is suitable. If you use a transformer without a midpoint in the secondary winding, then all elements of the second half-cycle must be excluded from the circuit. (Vk1, D5, D3). The circuit will be fully operational in both modes, only in the first it will work on one half-cycle. Thyristors can be used KU202 for a voltage of at least 60V. They can be installed on a radiator without insulation from each other. Diodes D4-7 any operating voltage of at least 60V. Transistors can be replaced with germanium low-frequency ones with appropriate conductivity. works on any pair of transistors: P40 - P9; MP39 - MP38; KT814 - KT815, etc. Any zener diode D1 for 12-14V. You can connect two in series to set the desired voltage. As an ammeter, I used a 10mA, 10 division milliammeter head. The shunt was selected experimentally, wound with a 1.2mm wire without a frame for a diameter of 8mm, 36 turns.
Charger setup. If assembled correctly, it works immediately. Sometimes it is necessary to set the limits of regulation Min - Max. selection of C1, usually upwards. If there are regulation failures, select R3. Usually I connected a powerful light bulb from a slide projector 24V x 300W as a load for adjustment. It is advisable to put a 10A fuse in the battery charge circuit break.
Discuss the article BATTERY CHARGER
Hello uv. reader of the blog "My amateur radio laboratory".
In today's article, we will talk about a long-used, but very useful circuit of a thyristor phase-pulse power controller, which we will use as a charger for lead-acid batteries.
Let's start with the fact that the charger on KU202 has a number of advantages:
- Ability to withstand a charge current of up to 10 amperes
- The charge current is pulsed, which, according to many radio amateurs, helps to extend the life of the battery
- The circuit is assembled from not scarce, inexpensive parts, which makes it very affordable in the price category
- And the last plus is the ease of repetition, which will make it possible to repeat it, both for a beginner in radio engineering and just for a car owner who has no knowledge of radio engineering at all, who needs high-quality and simple charging.
Over time, I tried a modified circuit with automatic battery shutdown, I recommend reading
At one time, I assembled this circuit on my knee in 40 minutes, along with the weed of the board and the preparation of circuit components. Well, enough stories, let's look at the scheme.
Scheme of a thyristor charger on KU202
List of used components in the circuit
C1 = 0.47-1uF 63V
R1 \u003d 6.8k - 0.25W
R2 = 300 - 0.25W
R3 \u003d 3.3k - 0.25W
R4 = 110 - 0.25W
R5 \u003d 15k - 0.25W
R6 \u003d 50 - 0.25W
R7 = 150 - 2W
FU1 = 10A
VD1 = current 10A, it is advisable to take a bridge with a margin. Well, at 15-25A and the reverse voltage is not lower than 50V
VD2 = any pulse diode, for reverse voltage not lower than 50V
VS1 = KU202, T-160, T-250
VT1 = KT361A, KT3107, KT502
VT2 = KT315A, KT3102, KT503
As mentioned earlier, the circuit is a thyristor phase-pulse power controller with an electronic charging current controller.
The thyristor electrode is controlled by a circuit based on transistors VT1 and VT2. The control current passes through VD2, which is necessary to protect the circuit from reverse current surges of the thyristor.
Resistor R5 determines the battery charging current, which should be 1/10 of the battery capacity. For example, a battery with a capacity of 55A must be charged with a current of 5.5A. Therefore, it is advisable to put an ammeter at the output in front of the charger terminals to control the charging current.
Regarding the power supply, for this circuit we select a transformer with an alternating voltage of 18-22V, preferably in terms of power without a margin, because we use a thyristor in control. If the voltage is greater, we raise R7 to 200 ohms.
Also, do not forget that the diode bridge and the control thyristor must be placed on radiators through heat-conducting paste. Also, if you use simple diodes such as D242-D245, KD203, remember that they must be isolated from the radiator housing.
We put a fuse on the output for the currents you need, if you do not plan to charge the battery with a current above 6A, then a 6.3A fuse will be enough for you.
Also, to protect your battery and charger, I recommend putting mine or, which, in addition to protection against polarity reversal, will protect the charger from connecting dead batteries with a voltage of less than 10.5V.
Well, in principle, we considered the charger circuit on KU202.
The printed circuit board of the thyristor charger on KU202
Assembled from Sergey
Good luck with your repetition and I look forward to your questions in the comments
For safe, high-quality and reliable charging of all types of batteries, I recommend
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Do not want to delve into the routine of radio electronics? I recommend paying attention to the proposals of our Chinese friends. For a very reasonable price, you can buy pretty high-quality chargers
Simple charger with LED charging indicator, green battery is charging, red battery is charged.
There is short circuit protection and reverse polarity protection. Perfect for charging Moto batteries with a capacity of up to 20A\h, a 9A\h battery will charge in 7 hours, 20A\h in 16 hours. Price for this charger 403 rubles, delivery is free
This type of charger is able to automatically charge almost any type of car and motorcycle batteries 12V up to 80Ah. It has a unique charging method in three stages: 1. Constant current charging, 2. Constant voltage charging, 3. Trickle charging up to 100%.
There are two indicators on the front panel, the first indicates the voltage and percentage of charge, the second indicates the charging current.
Pretty high-quality device for home needs, the price of everything 781.96 rubles, delivery is free. At the time of this writing number of orders 1392, grade 4.8 out of 5. When ordering, do not forget to specify europlug
Charger for a wide variety of types of batteries 12-24V with current up to 10A and peak current 12A. Able to charge Helium batteries and SA \ SA. The charging technology is the same as the previous one in three stages. The charger is capable of charging both in automatic mode and in manual mode. The panel has an LCD indicator indicating voltage, charge current and percentage of charge.
Under normal operating conditions, the vehicle's electrical system is self-sufficient. We are talking about power supply - a bunch of a generator, a voltage regulator, and a battery, works synchronously and provides uninterrupted power to all systems.
It's in theory. In practice, car owners amend this orderly system. Or the equipment refuses to work in accordance with the set parameters.
For example:
- Operating a battery that has reached its end of life. The battery does not hold a charge
- Irregular travel. A long idle time of the car (especially during the "winter hibernation") leads to battery self-discharge
- The car is used in the mode of short trips, with frequent muffling and starting the engine. The battery just can't get recharged.
- Connecting additional equipment increases the load on the battery. Often leads to increased self-discharge current when the engine is off
- Extremely low temperature accelerates self-discharge
- A faulty fuel system leads to increased load: the car does not start immediately, you have to turn the starter for a long time
- A faulty alternator or voltage regulator prevents the battery from charging normally. This problem includes frayed power wires and poor contact in the charge circuit.
- And finally, you forgot to turn off the headlights, dimensions or music in the car. To completely discharge the battery overnight in the garage, sometimes it is enough to loosely close the door. Interior lighting consumes a lot of energy.
Any of the following causes an unpleasant situation: you have to go, and the battery is unable to crank the starter. The problem is solved by external recharge: that is, a charger.
In the tab, there are four proven and reliable charger schemes for a car, from the simplest to the most complex. Choose any and it will work.
A simple 12V charger circuit.
Charger with adjustable charging current.
Adjustment from 0 to 10A is carried out by changing the delay in opening the trinistor. 
Diagram of a battery charger with self-shutoff after charging.
For charging batteries with a capacity of 45 amperes.
The scheme of a smart charger that will warn of incorrect connection. 
It is quite easy to assemble with your own hands. An example of a charger made from an uninterruptible power supply.
Under normal operating conditions, the vehicle's electrical system is self-sufficient. We are talking about power supply - a bunch of a generator, a voltage regulator, and a battery, works synchronously and provides uninterrupted power to all systems.
It's in theory. In practice, car owners amend this orderly system. Or the equipment refuses to work in accordance with the set parameters.
For example:
- Operating a battery that has reached its end of life. The battery does not hold a charge
- Irregular travel. A long idle time of the car (especially during the "winter hibernation") leads to battery self-discharge
- The car is used in the mode of short trips, with frequent muffling and starting the engine. The battery just can't get recharged.
- Connecting additional equipment increases the load on the battery. Often leads to increased self-discharge current when the engine is off
- Extremely low temperature accelerates self-discharge
- A faulty fuel system leads to increased load: the car does not start immediately, you have to turn the starter for a long time
- A faulty alternator or voltage regulator prevents the battery from charging normally. This problem includes frayed power wires and poor contact in the charge circuit.
- And finally, you forgot to turn off the headlights, dimensions or music in the car. To completely discharge the battery overnight in the garage, sometimes it is enough to loosely close the door. Interior lighting consumes a lot of energy.
Any of the following causes an unpleasant situation: you have to go, and the battery is unable to crank the starter. The problem is solved by external recharge: that is, a charger.
It is quite easy to assemble with your own hands. An example of a charger made from an uninterruptible power supply.
Any car charger circuit consists of the following components:
- Power unit.
- Current stabilizer.
- Charge current regulator. Can be manual or automatic.
- Indicator of current level and (or) charge voltage.
- Optional - charge control with automatic shutdown.
Any charger, from the simplest to the smart machine, consists of the listed elements or their combination.
Simple scheme for a car battery
Normal charge formula as simple as 5 kopecks - the basic battery capacity divided by 10. The charge voltage should be a little over 14 volts (we are talking about a standard 12 volt starter battery).
Simple principle electrical car charger circuit has three components: power supply, regulator, indicator.
Classic - resistor charger
The power supply is made of two winding "trance" and a diode assembly. The output voltage is selected by the secondary winding. The rectifier is a diode bridge, the stabilizer is not used in this circuit.
The charge current is regulated by a rheostat.
Important! No variable resistors, even on a ceramic core, can withstand such a load.
Wire rheostat necessary to counter the main problem of such a scheme - excess power is released in the form of heat. And it happens very intensively.
Of course, the efficiency of such a device tends to zero, and the resource of its components is very low (especially the rheostat). Nevertheless, the scheme exists, and it is quite efficient. For emergency charging, if there is no ready-made equipment at hand, you can literally assemble it “on your knee”. There are also limitations - a current of more than 5 amperes is the limit for such a circuit. Therefore, you can charge a battery with a capacity of not more than 45 Ah.
DIY charger, details, diagrams - video
quenching capacitor
The principle of operation is shown in the diagram.
Due to the reactance of the capacitor included in the primary winding circuit, it is possible to regulate the charging current. The implementation consists of the same three components - a power supply, a regulator, an indicator (if necessary). The circuit can be configured to charge one type of battery, and then the indicator will not be needed.
If we add one more element - automatic charge control, and also assemble the switch from a whole bank of capacitors - you get a professional charger that remains easy to manufacture.
Charge control and automatic shutdown scheme, no comments needed. The technology has been worked out, you can see one of the options in the general diagram. The threshold is set by a variable resistor R4. When the voltage at the battery terminals reaches the set level, relay K2 disconnects the load. An ammeter acts as an indicator, which stops showing the charge current.
The highlight of the charger- capacitor bank. A feature of circuits with a quenching capacitor is that by adding or reducing capacitance (simply by connecting or removing additional elements), you can adjust the output current. By selecting 4 capacitors for currents 1A, 2A, 4A and 8A, and switching them with ordinary switches in various combinations, you can adjust the charge current from 1 to 15 A in 1 A steps.
If you are not afraid to hold a soldering iron in your hands, you can assemble a car accessory with smooth adjustment of the charge current, but without the drawbacks inherent in the resistor classics.
As a regulator, not a heat dissipator in the form of a powerful rheostat is used, but an electronic key on a thyristor. The entire power load passes through this semiconductor. This circuit is designed for current up to 10 A, that is, it allows you to charge batteries up to 90 Ah without overloading.
By adjusting the degree of opening of the transition on the transistor VT1 with resistor R5, you provide smooth and very accurate control of the trinistor VS1.
The scheme is reliable, easy to assemble and set up. But there is one condition that prevents such a charger from being included in the list of successful designs. The power of the transformer must provide a threefold margin for the charge current.
That is, for an upper limit of 10 A, the transformer must withstand a continuous load of 450-500 watts. A practically implemented scheme will be cumbersome and heavy. However, if the charger is permanently installed indoors, this is not a problem.
Scheme of a pulse charger for a car battery
All the flaws the solutions listed above can be changed to one - the complexity of the assembly. This is the essence of pulse chargers. These circuits have an enviable power, heat up little, and have a high efficiency. In addition, their compact size and light weight make it easy to carry them with you in the glove compartment of your car.
The circuitry is understandable to any radio amateur who has an idea of what a PWM generator is. It is assembled on the popular (and completely non-deficient) IR2153 controller. In this circuit, a classic semi-bridge inverter is implemented.
With the available capacitors, the output power is 200 watts. This is a lot, but the load can be doubled by replacing the capacitors with 470 microfarad capacitances. Then it will be possible to charge up to 200 Ah.
The assembled board turned out to be compact, it fits in a box 150 * 40 * 50 mm. No forced cooling required but ventilation holes must be provided. If you increase the power to 400 W, the power switches VT1 and VT2 should be installed on the radiators. They need to be taken out of the box.
The power supply from the PC system unit can act as a donor.
Important! When using an AT or ATX power supply, there is a desire to convert the finished circuit into a charger. To implement such an undertaking, a factory power supply circuit is required.
Therefore, we simply use the element base. Perfect transformer, inductor and diode assembly (Schottky) as a rectifier. Everything else: transistors, capacitors and other trifles - usually available from a radio amateur in all sorts of boxes-drawers. So the charger is conditionally free.
The video shows and tells how to assemble your own impulse charger for a car.
The cost of a factory impulse switch for 300-500 W is at least $ 50 (equivalent).
Conclusion:
Collect and use. Although it is wiser to keep your battery "in good shape."
Compliance with the operating mode of batteries, and in particular the charging mode, guarantees their trouble-free operation throughout the entire service life. The batteries are charged with a current, the value of which can be determined by the formula
where I is the average charging current, A., and Q is the nameplate electric capacity of the battery, Ah.
A classic car battery charger consists of a step-down transformer, a rectifier and a charging current regulator. Wire rheostats are used as current regulators (see Fig. 1) and transistor current stabilizers.
In both cases, significant thermal power is released on these elements, which reduces the efficiency of the charger and increases the likelihood of its failure.
To adjust the charging current, you can use a store of capacitors that are connected in series with the primary (mains) winding of the transformer and act as reactances that dampen excess mains voltage. A simplified version of such a device is shown in Fig. 2.
In this circuit, thermal (active) power is released only on the diodes VD1-VD4 of the rectifier bridge and the transformer, so the heating of the device is negligible.
The disadvantage in Fig. 2 is the need to ensure the voltage on the secondary winding of the transformer is one and a half times greater than the load (~ 18÷20V).
The charger circuit that provides charging of 12-volt batteries with a current of up to 15 A, and the charging current can be changed from 1 to 15 A in steps of 1 A, is shown in Fig. 3.
It is possible to automatically turn off the device when the battery is fully charged. It is not afraid of short-term short circuits in the load circuit and breaks in it.
With switches Q1 - Q4, you can connect various combinations of capacitors and thereby regulate the charging current.
The variable resistor R4 sets the threshold K2, which should be triggered when the voltage at the battery terminals is equal to the voltage of a fully charged battery.
On Fig. 4 shows another charger, in which the charging current is continuously adjustable from zero to the maximum value.
The change in the current in the load is achieved by adjusting the opening angle of the trinistor VS1. The control unit is made on a unijunction transistor VT1. The value of this current is determined by the position of the variable resistor R5 slider. The maximum battery charge current is 10A, set by an ammeter. The device is provided on the mains and load side by fuses F1 and F2.
A variant of the printed circuit board of the charger (see Fig. 4), 60x75 mm in size, is shown in the following figure:
In the diagram in fig. 4 the secondary winding of the transformer must be designed for a current three times the charging current, and accordingly the power of the transformer must also be three times the power consumed by the battery.
This circumstance is a significant drawback of chargers with a current regulator trinistor (thyristor).
Note:
Rectifier bridge diodes VD1-VD4 and thyristor VS1 must be installed on radiators.
It is possible to significantly reduce power losses in the trinistor, and therefore increase the efficiency of the charger, by transferring the control element from the secondary winding circuit of the transformer to the primary winding circuit. such a device is shown in Fig. 5.
In the diagram in Fig. 5, the control unit is similar to that used in the previous version of the device. The trinistor VS1 is included in the diagonal of the rectifier bridge VD1 - VD4. Since the current of the primary winding of the transformer is about 10 times less than the charge current, a relatively small thermal power is released on the VD1-VD4 diodes and the VS1 trinistor and they do not require installation on radiators. In addition, the use of a trinistor in the primary circuit of the transformer made it possible to slightly improve the shape of the charging current curve and reduce the shape factor of the current curve (which also leads to an increase in the efficiency of the charger). The disadvantage of this charger is the galvanic connection with the network of elements of the control unit, which must be taken into account when developing the design (for example, use a variable resistor with a plastic axis).
A variant of the printed circuit board of the charger in Figure 5, 60x75 mm in size, is shown in the figure below:
Note:
Rectifier bridge diodes VD5-VD8 must be installed on radiators.
In the charger in Figure 5, there is a diode bridge VD1-VD4 of the type KTs402 or KTs405 with the letters A, B, C. A zener diode VD3 of the type KS518, KS522, KS524, or composed of two identical zener diodes with a total stabilization voltage of 16 ÷ 24 volts (KS482, D808, KS510, etc.). Transistor VT1 is single-junction, type KT117A, B, C, G. The diode bridge VD5-VD8 is made up of diodes, with a working current not less than 10 amperes(D242÷D247 and others). Diodes are installed on radiators with an area of at least 200 sq.cm, and the radiators will get very hot, you can install a fan for blowing into the charger case.
Thyristor regulator in charger.
For a more complete introduction to the following material, see previous articles: And.
♣ These articles say that there are 2 half-wave rectification circuits with two secondary windings, each of which is designed for the full output voltage. The windings work alternately: one on the positive half-wave, the other on the negative.
Two semiconductor rectifier diodes are used.
♣ Preference for this scheme:
- - the current load on each winding and each diode is two times less than on a circuit with one winding;
- - the cross section of the wire of the two secondary windings can be half as much;
- - rectifier diodes can be selected for a lower maximum allowable current;
- - the wires of the windings cover the magnetic circuit the most, the magnetic stray field is minimal;
- - complete symmetry - the identity of the secondary windings;
♣ We use such a rectification scheme on a U-shaped core for the manufacture of an adjustable thyristor charger.
Two - frame design of the transformer allows you to do this in the best way.
In addition, the two half-windings are exactly the same.
♣ And so, our exercise: build a battery charger device with voltage 6 – 12
volt and smooth regulation of the charging current 0 to 5 amps
.
I have already suggested for manufacturing, but the adjustment of the charging current in it is carried out in steps.
See in this article how the transformer was calculated on W - shaped core. These estimates are also suitable for U-shaped transformer of the same power.
The calculated data from the article is as follows:
- - transformer power - 100 watts ;
- - section of the core - 12 cm.sq.;
- - rectified voltage - 18 volt;
- - current - up to 5 amps;
- - number of turns per volt - 4,2 .
Primary winding:
- - number of turns - 924 ;
- - current - 0,45 ampere;
- - wire diameter - 0,54 mm.
Secondary winding:
- - number of turns - 72 ;
- - current - 5 ampere;
- - wire diameter - 1,8 mm.
♣ We will take these calculated data as the basis for building a transformer based on P- shaped core.
Taking into account the recommendations of the above articles on the manufacture of a transformer for P- shaped core, we will build a rectifier for charging the battery with smooth adjustment of the charging current
.
The rectifier circuit is shown in the figure. It consists of a transformer TR, thyristors T1 and T2, charging current control circuits, ammeter on 5 - 8
ampere, diode bridge D4 - D7.
Thyristors T1 and T2 simultaneously perform the role of rectifier diodes and the role of regulators of the magnitude of the charging current.
♣ Transformer Tr consists of a magnetic circuit and two frames with windings.
The magnetic core can be assembled both from steel P- shaped plates, and from cut ABOUT- a shaped core of wound steel tape.
Primary winding (network for 220 volts - 924 turns) divided in half - 462 turns (a - a1) on one frame 462 turns (b - b1) on another frame.
Secondary winding (at 17 volts) consists of two half-windings (72 turns each) dangles on the first (A - B) and on the second (A1 – B1) framework 72 turns. Total 144
coil.
Third winding (c - c1 = 36 turns) + (d - d1 = 36 turns) in total 8.5 V +8.5 V = 17 volts serves to power the control circuit and consists of 72
turns of wire. On one frame (c - c1) 36 turns and on the other frame (d - d1) 36 turns.
The primary winding is wound with a wire with a diameter of - 0.54 mm.
Each secondary half-winding is wound with a wire with a diameter 1.3 mm., rated for current 2,5
ampere.
The third winding is wound with a wire with a diameter 0.1 - 0.3 mm, which one comes across, the current consumption here is small.
♣ Smooth adjustment of the charging current of the rectifier is based on the property of the thyristor to switch to the open state by the pulse arriving at the control electrode. By adjusting the arrival time of the control pulse, it is possible to control the average power passing through the thyristor for each period of alternating electric current.
♣ The above thyristor control circuit works on the principle phase-pulse method.
The control circuit consists of an analogue of a thyristor assembled on transistors Tr1 and Tr2, a time chain consisting of a capacitor WITH and resistors R2 and Ry, zener diode D 7 and separating diodes D1 and D2. The charging current is regulated by a variable resistor Ry.
AC voltage 17 volt removed from the third winding, rectified by a diode bridge D3 - D6 and has the form (point No. 1) (in the circle No. 1). This is a pulsating voltage of positive polarity with a frequency 100 hertz, changing its value 0 to 17 volts. Through a resistor R5 voltage is applied to the zener diode D7 (D814A, D814B or any other 8 - 12 volts). At the zener diode, the voltage is limited to 10 volts and has the form ( point number 2). Next comes the charge-discharge chain. (Ry, R2, C). As the voltage rises from 0, the capacitor begins to charge. WITH, through resistors Ry, and R2.
♣ Resistor resistance and capacitor capacitance (Ry, R2, C) are selected in such a way that the capacitor is charged during the action of one half-cycle of the pulsating voltage. When the voltage across the capacitor reaches its maximum value (point number 3), with resistors R3 and R4 to the control electrode of the thyristor analogue (transistors Tr1 and Tr2) will receive voltage to open. The analogue of the thyristor will open and the charge of electricity accumulated in the capacitor will be released on the resistor R1. Resistor pulse shape R1 shown in a circle №4
.
via separating diodes D1 and D2 the start pulse is applied simultaneously to both control electrodes of the thyristors T1 and T2. The thyristor opens, which at the moment has received a positive half-wave of alternating voltage from the secondary windings of the rectifier (point number 5).
By changing the resistance of the resistor Ry, change the time for which the capacitor is fully charged WITH, that is, we change the turn-on time of the thyristors during the action of the half-wave voltage. IN point number 6 shows the voltage waveform at the output of the rectifier.
The resistance Ry changes, the time of the beginning of the opening of the thyristors changes, the form of filling the half-cycle with the active current changes (figure No. 6). The half-cycle filling can be adjusted from 0 to maximum. The whole process of voltage regulation over time is shown in the figure.
♣ All voltage waveform measurements shown in points #1 - #6 drawn relative to the positive terminal of the rectifier.
Rectifier details:
- thyristors T1 and T2 - KU 202I-N for 10 amperes. Each thyristor is installed on a radiator with an area 35 - 40 cm.sq.;
- diodes D1 - D6 D226 or any on current 0.3 ampere and higher voltage 50 volts;
- zener diode D7 - D814A - D814G or any other 8 - 12 volts;
- transistors Tr1 and Tr2 any low-power voltage over 50 volts.
It is necessary to select a pair of transistors with the same power, different conductivities and equal gains (at least 35 - 50
).
I tested different pairs of transistors: KT814 - KT815, KT816 - KT817; MP26 - KT308, MP113 - MP114.
All options worked well.
- Capacitor 0.15 microfarads;
- Resistor R5 set the power to 1 watt. The rest of the power resistors 0.5 watt.
- The ammeter is rated for current 5 - 8 amps
♣ Pay attention to the installation of the transformer. I advise you to read the article. Especially the place where recommendations are given on the phasing of the inclusion of the primary and secondary windings.
You can use the primary winding phasing scheme below, as in the figure.
♣ An electric light bulb is connected in series to the primary winding circuit for voltage 220 volt and power 60 watts. this bulb will serve as a fuse.
If the windings are in phase wrong, bulb will light up.
If connections are made Right, when the transformer is connected to the network 220 volt light bulb should flare up and fade away.
There should be two voltages at the terminals of the secondary windings 17 volts, together (between A and B) 34 volts.
All installation work must be carried out in compliance with ELECTRICAL SAFETY REGULATIONS!
The device with electronic control of the charging current is made on the basis of a thyristor phase-pulse power controller. It does not contain scarce parts; with obviously good elements, it does not require adjustment.
The charger allows you to charge car batteries with a current of 0 to 10 A, and can also serve as an adjustable power source for a powerful low-voltage soldering iron, vulcanizer, portable lamp. Charging current is close to pulsed in shape, which is believed to prolong battery life. The device is operable at ambient temperature from - 35 °С to + 35 °С.
The scheme of the device is shown in fig. 2.60.
The charger is a thyristor power regulator with phase-pulse control, fed from the winding II of the step-down transformer T1 through the diode moctVDI + VD4.
The thyristor control unit is made on the analog of the unijunction transistor VT1, VT2 The time during which the capacitor C2 is charged before switching the unijunction transistor can be adjusted by the variable resistor R1. With the extreme right position of its engine according to the diagram, the charging current will be maximum, and vice versa.
Diode VD5 protects the control circuit of the thyristor VS1 from the reverse voltage that occurs when the thyristor is turned on.
In the future, the charger can be supplemented with various automatic units (shutdown at the end of charging, maintaining normal battery voltage during long-term storage, signaling the correct polarity of the battery connection, protection against output short circuits, etc.).
The disadvantages of the device include fluctuations in the charging current with an unstable voltage of the electric lighting network.
Like all similar thyristor phase-pulse controllers, the device interferes with radio reception. To combat them, you should provide a network LC filter, similar to that used in switching network power supplies.
Capacitor C2 - K73-11, with a capacity of 0.47 to 1 uF, or. K73-16, K73-17, K42U-2, MBGP.
We will replace the KT361A transistor with KT361B - KT361Yo, KT3107L, KT502V, KT502G, KT501Zh - KT50IK, and KT315L - with KT315B + KT315D KT312B, KT3102L, KT503V + KT503G, P307 Instead of KD 105B fit diodes KD105V, KD105G or. D226 with any letter index.
Variable resistor R1 - SP-1, SPZ-30a or SPO-1.