Charger for car battery on TL494. Practical diagrams of universal battery chargers Car charger for tl494

CHARGERS FOR CAR BATTERIES

Another charger assembled according to the circuit of a key current stabilizer with a unit for monitoring the achieved voltage on the battery to ensure that it is turned off at the end of charging. A widely used specialized microcircuit is used to control the key transistor TL494 (KIA494, KA7500B, K1114UE4). The device provides charge current regulation within 1 ... 6 A (10A max) and output voltage 2 ... 20 V.

Key transistor VT1, diode VD5 and power diodes VD1 - VD4 through mica spacers must be installed on a common radiator with an area of ​​200 ... 400 cm2. The most important element in the circuit is the inductor L1. The quality of its manufacture depends on Circuit efficiency. The requirements for its manufacture are described in As a core, you can use a pulse transformer from the power supply of 3USTST TVs or a similar one. It is very important that the magnetic core has a slot gap of approximately 0.2 ... 1, 0 mm to prevent saturation at high currents. The number of turns depends on the specific magnetic circuit and can be in the range of 15 ... 100 turns of PEV-2 2.0 mm wire. If the number of turns is excessive, a soft whistling sound will be heard when the circuit operates at rated load. As a rule, the whistling sound occurs only at medium currents, and at high loads the inductance of the inductor due to the magnetization of the core drops and the whistling stops. If the whistling sound stops at low currents and with a further increase in the load current the output transistor begins to heat up sharply, then the area of ​​the magnetic core is insufficient to operate at the selected generation frequency - it is necessary to increase the operating frequency of the microcircuit selection of resistor R4 or capacitor C3 or install a larger choke. In the absence of a power transistor structure p-n-p can be used in the diagram powerful transistors structures n-p-n as shown in the picture.

Car charger or adjustable laboratory block power supply with an output voltage of 4 - 25 V and a current of up to 12A can be made from an unnecessary computer AT or ATX power supply.

Let's look at several scheme options below:

Options

From computer unit power supply with a power of 200W, you can actually get 10 - 12A.

AT power supply circuit for TL494

Several ATX power supply circuits for TL494

Rework

The main alteration is as follows: we unsolder all the extra wires coming from the power supply to the connectors, leave only 4 pieces of yellow +12V and 4 pieces of black housing, twist them into bundles. We find on the board a microcircuit with number 494, in front of the number there may be different letters DBL 494, TL 494, as well as analogues MB3759, KA7500 and others with a similar connection circuit. We are looking for a resistor going from the 1st leg of this microcircuit to +5 V (this is where the red wire harness was) and remove it.

For an regulated (4V - 25V) power supply, R1 should be 1k. Also, for the power supply, it is desirable to increase the capacity of the electrolyte at the 12V output (for a charger it is better to exclude this electrolyte), make several turns on a ferrite ring with a yellow beam (+12V) (2000NM, 25 mm in diameter is not critical).

It should also be borne in mind that on the 12 volt rectifier there is a diode assembly (or 2 back-to-back diodes) rated for a current of up to 3 A, it should be replaced with the one on the 5 volt rectifier, it is rated up to 10 A, 40 V , it is better to install the BYV42E-200 diode assembly (Schottky diode assembly Ipr = 30 A, V = 200 V), or 2 back-to-back powerful diodes KD2999 or similar ones in the table below.

If you need to connect the soft-on pin to the common wire to start the ATX power supply (the green wire goes to the connector). The fan needs to be turned 180 degrees so that it blows inside the unit, if you are using it as a power supply, it is better to power the fan with the 12th the legs of the microcircuit through a 100 Ohm resistor.

It is advisable to make the body from dielectric, not forgetting about ventilation holes there should be enough of them. Native metal case, use at your own risk.

It happens that when you turn on the power supply at a high current, the protection may work, although for me it doesn’t work at 9A, if anyone encounters this, you should delay the load when turning it on for a couple of seconds.

Another interesting option for redesigning a computer power supply.

In this circuit, voltage (from 1 to 30 V) and current (from 0.1 to 10A) are adjusted.

For homemade block Voltage and current indicators work well. You can buy them on the Trowel website.

P O P U L A R N O E:

When I go out by car, I take my laptop with me...

One day I came across an article on an amateur radio website about how to make a car adapter for a laptop.

A simple circuit (see below) - one microcircuit and a pair of transistors...

Scheme:

Charger assembled according to the circuit of a key current stabilizer with a unit for monitoring the achieved voltage on the battery to ensure that it is turned off at the end of charging. To control the key transistor, a widely used specialized chip TL494 (KIA491, K1114UE4). The device provides regulation of the charge current within 1 ... 6 A (10 A max) and output voltage 2 ... 20 V.

The key transistor VT1, diode VD5 and power diodes VD1 - VD4 through mica spacers must be installed on a common radiator with an area of ​​200 ... 400 cm2. The most important element in the circuit is inductor L1. The efficiency of the circuit depends on the quality of its manufacture. As a core, you can use a pulse transformer from a 3USTST TV power supply or similar. It is very important that the magnetic core has a slot gap of approximately 0.5 ... 1.5 mm to prevent saturation at high currents. The number of turns depends on the specific magnetic circuit and can be in the range of 15 ... 100 turns of PEV-2 2.0 mm wire. If the number of turns is excessive, a soft whistling sound will be heard when the circuit operates at rated load. As a rule, the whistling sound occurs only at medium currents, and at high loads the inductance of the inductor due to the magnetization of the core drops and the whistling stops. If the whistling sound stops at low currents and with a further increase in the load current the output transistor begins to heat up sharply, then the area of ​​the magnetic core is insufficient to operate at the selected generation frequency - it is necessary to increase the operating frequency of the microcircuit by selecting resistor R4 or capacitor C3 or install a larger inductor. If there is no power transistor of the p-n-p structure in the circuit, you can use powerful transistors n-p-n structures as shown in the picture.

Details:
As a diode VD5 in front of inductor L1, it is advisable to use any available diodes with a Schottky barrier, rated for a current of at least 10A and a voltage of 50V; in extreme cases, you can use mid-frequency diodes KD213, KD2997 or similar imported ones. For the rectifier, you can use any powerful diodes with a current of 10A or diode bridge, for example KBPC3506, MP3508 or similar. It is advisable to adjust the shunt resistance in the circuit to the required value. The range of adjustment of the output current depends on the ratio of the resistances of the resistors in the output circuit 15 of the microcircuit. In the lower position of the current adjustment variable resistor slider in the diagram, the voltage at pin 15 of the microcircuit must match the voltage on the shunt when flowing through it maximum current. The variable current control resistor R3 can be set with any nominal resistance, but you will need to select a fixed resistor R2 adjacent to it to obtain the required voltage at pin 15 of the microcircuit.
The variable output voltage adjustment resistor R9 can also have a wide range of nominal resistance 2 ... 100 kOhm. By selecting the resistance of resistor R10, the upper limit of the output voltage is set. The lower limit is determined by the ratio of the resistances of resistors R6 and R7, but it is undesirable to set it below 1 V.

The microcircuit is installed on a small printed circuit board 45 x 40 mm, the remaining elements of the circuit are installed on the base of the device and the radiator.
PCB:

Wiring diagram:

The circuit used a rewound TS180 power transformer, but depending on the magnitude of the required output voltages and current, the power of the transformer can be changed. If an output voltage of 15 V and a current of 6 A are sufficient, then power transformer power 100 W. The radiator area can also be reduced to 100...200 cm2. The device can be used as a laboratory power supply with adjustable output current limitation. If the elements are in good working order, the circuit begins to work immediately and only requires adjustment.

Another charger is assembled according to the circuit of a key current stabilizer with a unit for monitoring the achieved voltage on the battery to ensure that it is turned off at the end of charging. To control the key transistor, a widely used specialized microcircuit TL494 (KIA491, K1114UE4) is used. The device provides regulation of the charge current within 1 ... 6 A (10 A max) and output voltage 2 ... 20 V.

The key transistor VT1, diode VD5 and power diodes VD1 - VD4 through mica spacers must be installed on a common radiator with an area of ​​200 ... 400 cm2. The most important element in the circuit is inductor L1. The efficiency of the circuit depends on the quality of its manufacture. As a core, you can use a pulse transformer from a 3USTST TV power supply or similar. It is very important that the magnetic core has a slot gap of approximately 0.5 ... 1.5 mm to prevent saturation at high currents. The number of turns depends on the specific magnetic circuit and can be in the range of 15 ... 100 turns of PEV-2 2.0 mm wire. If the number of turns is excessive, a soft whistling sound will be heard when the circuit operates at rated load. As a rule, the whistling sound occurs only at medium currents, and at high loads the inductance of the inductor due to the magnetization of the core drops and the whistling stops. If the whistling sound stops at low currents and with a further increase in the load current the output transistor begins to heat up sharply, then the area of ​​the magnetic core is insufficient to operate at the selected generation frequency - it is necessary to increase the operating frequency of the microcircuit by selecting resistor R4 or capacitor C3 or install a larger inductor. If there is no power transistor of the p-n-p structure in the circuit, you can use powerful transistors of the n-p-n structure, as shown in the figure.

As a diode VD5 in front of inductor L1, it is advisable to use any available diodes with a Schottky barrier, rated for a current of at least 10A and a voltage of 50V; in extreme cases, you can use mid-frequency diodes KD213, KD2997 or similar imported ones. For the rectifier, you can use any powerful diodes with a current of 10A or a diode bridge, for example KBPC3506, MP3508 or the like. It is advisable to adjust the shunt resistance in the circuit to the required value. The range of adjustment of the output current depends on the ratio of the resistances of the resistors in the output circuit 15 of the microcircuit. In the lower position of the current control variable resistor slider in the diagram, the voltage at pin 15 of the microcircuit must coincide with the voltage on the shunt when the maximum current flows through it. The variable current control resistor R3 can be set with any nominal resistance, but you will need to select a fixed resistor R2 adjacent to it to obtain the required voltage at pin 15 of the microcircuit.
The variable output voltage adjustment resistor R9 can also have a wide range of nominal resistance 2 ... 100 kOhm. By selecting the resistance of resistor R10, the upper limit of the output voltage is set. The lower limit is determined by the ratio of the resistances of resistors R6 and R7, but it is undesirable to set it below 1 V.

The microcircuit is installed on a small printed circuit board 45 x 40 mm, the remaining elements of the circuit are installed on the base of the device and the radiator.

The wiring diagram for connecting the printed circuit board is shown in the figure below.

Options printed circuit boards in lay6

We say thank you for the seals in the comments Demo

The circuit used a rewound TS180 power transformer, but depending on the magnitude of the required output voltages and current, the power of the transformer can be changed. If an output voltage of 15 V and a current of 6 A is sufficient, then a power transformer with a power of 100 W is sufficient. The radiator area can also be reduced to 100...200 cm2. The device can be used as a laboratory power supply with adjustable output current limitation. If the elements are in good working order, the circuit begins to work immediately and only requires adjustment.

Source: http://shemotechnik.ru

So. We have already looked at the half-bridge inverter control board; it’s time to put it into practice. Let's take a typical half-bridge circuit; it does not cause any particular difficulties in assembly. The transistors are connected to the corresponding terminals of the board, a standby power supply of 12-18 volts is supplied. If 3 diodes are connected in series, the voltage at the gates will drop by 2 volts and we will get exactly the required 10-15 volts.

Let's look at the diagram:
The transformer is calculated by the program or simplified using the formula N=U/(4*pi*F*B*S). U=155V, F=100000 hertz with RC ratings of 1nf and 4.7kOhm, B=0.22 T for the average ferrite, regardless of permeability, the only variable parameter that remains is S - the cross-sectional area of ​​the side of the ring or the middle rod Ш of the magnetic circuit in square meters.

The throttle is calculated using the formula L=(Uppeak-Ustab)*Тdead/Imin. However, the formula is not very convenient - the dead time depends on the difference between the peak and stabilized voltage. The stabilized voltage is the arithmetic mean of the sample from the output pulses (not to be confused with the root mean square). For a power supply that is regulated over the full range, the formula can be rewritten as L= (Upeak*1/(2*F))/Imin. It can be seen that, in the case of complete voltage regulation, the more inductance is needed, the lower the minimum current value. What will happen if the power supply is loaded with less than a current Imin. And everything is very simple - the voltage will tend to the peak value, it seems to ignore the inductor. In the case of feedback regulation, the voltage will not be able to rise; instead, the pulses will be suppressed so that only their fronts remain, stabilization will occur due to heating of the transistors, essentially a linear stabilizer. I think it is correct to take Imin such that the linear mode losses are equal to the losses at maximum load. Thus, the adjustment remains in full range and is not dangerous for the power supply.

The output rectifier is built using a full-wave circuit with a midpoint. This approach allows you to halve the voltage drop across the rectifier and allows you to use ready-made diode assemblies with a common cathode, which are no more expensive than a single diode, for example MBR20100CT or 30CTQ100. The first digits of the marking mean a current of 20 and 30 amperes, respectively, and the second digits mean a voltage of 100 volts. It is worth considering that the diodes will have double voltage. Those. we get 12 volts at the output, and at the same time there will be 24 on the diodes.

Half-bridge transistors.. And here it’s worth thinking about what we need. Relatively low-power transistors like IRF730 or IRF740 can operate at very high frequencies, 100 kilohertz is not the limit for them, and besides, we do not risk a control circuit built on not very powerful parts. For comparison, the gate capacitance of the 740 transistor is only 1.8 nf, and the IRFP460 is as much as 10 nf, which means 6 times more power will be used to transfer the capacitance each half-cycle. Plus, this will tighten the fronts. For static losses, you can write P=0.5*Ropen *Itr^2 for each transistor. In words - the resistance of an open transistor multiplied by the square of the current through it, divided by two. And these losses are usually several watts. Another thing is dynamic losses, these are losses on the fronts, when the transistor passes through the hated mode A, and this evil mode causes losses, roughly described as the maximum power multiplied by the ratio of the duration of both fronts to the duration of the half-cycle, divided by 2. For each transistor. And these losses are much more than static. Therefore, if you take a more powerful transistor when
you can get by with an easier option, you can even lose in efficiency, so don’t abuse it.

Looking at the input and output capacitances, you may want to make them too large, and this is quite logical, because despite the operating frequency of the power supply of 100 kilohertz, we still rectify the mains voltage of 50 hertz, and in case of insufficient capacitance we will get the same output rectified sine wave, it is remarkably modulated and demodulated back. So you should look for pulsations at a frequency of 100 hertz. For those who are afraid of “HF noise”, I assure you that there is not a drop of it, it was checked with an oscilloscope. But increasing the capacitances can lead to huge inrush currents, and they will certainly cause damage to the input bridge, and inflated output capacitances will also lead to an explosion of the entire circuit. To correct the situation, I made some additions to the circuit - a relay for monitoring the charge of the input capacitance and a soft start on the same relay and capacitor C5. I’m not responsible for the ratings, I can only say that C5 will be charged through resistor R7, and the charging time can be estimated using the formula T=2pRC, the output capacitance will be charged at the same speed, charging with a stable current is described by U=I*t/C, although not exactly, but it is possible to estimate the current surge depending on time. By the way, without a throttle it makes no sense.

Let's look at what came out after modification:

Current stabilization here plays more of a protective role, although adjustment is possible with a variable resistor. Implemented through a current transformer, because it was adapted to a power supply with a bipolar output, but it’s not all that simple. The calculation of this transformer is very simple - a shunt with a resistance of R Ohm is transferred to the secondary winding with the number of turns N as resistance Rнт=R*N^2, you can express the voltage from the ratio of the number of turns and the drop on the equivalent shunt, it should be greater than the drop voltage diode. The current stabilization mode will begin when the voltage at the + input of the op-amp tries to exceed the voltage at the - input. Based on this calculation. The primary winding is a wire pulled through a ring. It is worth considering that a break in the load of a current transformer can lead to the appearance of huge voltages at its output, at least sufficient to break down the error amplifier.

Capacitors C4 C6 and resistors R10 R3 form a differential amplifier. Due to the chain R10 C6 and the mirrored R3 C4, we obtain a triangular decline in the amplitude-frequency response of the error amplifier. This looks like a slow change in pulse width depending on the current. On the one hand, this reduces the feedback speed, on the other hand, it makes the system stable. The main thing here is to ensure that the frequency response falls below 0 decibels at a frequency of no more than 1/5 of the shim frequency; such feedback is quite fast, unlike feedback from the output of the LC filter. The start frequency of the cutoff at -3dB is calculated as F=1/2pRC where R=R10=R3; C=C6=C4, I’m not responsible for the values ​​in the diagram, I didn’t count them. Own gain

The circuit is calculated as the ratio of the maximum possible voltage (dead time tends to zero) on capacitor C4 to the voltage of the saw generator built into the chip and converted to decibels. It raises the frequency response of the closed system upward. Considering that our compensating chains give a decline of 20 dB per decade starting from a frequency of 1/2pRC and knowing this rise, it is not difficult to find the point of intersection with 0 dB, which should be no more than at a frequency of 1/5 of the operating frequency, i.e. 20 kilohertz. It is worth noting that the transformer should not be wound with a huge power reserve, on the contrary, the short-circuit current should not be particularly large, otherwise even such high-frequency protection will not be able to work on time, and what if a kiloampere jumps out there.. So we don’t abuse this either .

That's all for today, I hope the diagram will be useful. It can be adapted for a power screwdriver, or a bipolar output can be made to power an amplifier; it is also possible to charge batteries with a stable current. For complete wiring of tl494 we refer to the last part; the only additions to it are the capacitor soft start C5 and the relay contacts on it. Well, an important note - monitoring the voltage on the half-bridge capacitors forced us to connect the control circuit with power in such a way that this will not allow the use of standby power with a quenching capacitor, at least with bridge rectification. Possible solution- a half-wave rectifier such as a diode half-bridge or a transformer in the duty room.

TL494 in a full power supply

More than a year has passed since I seriously took up the topic of power supplies. I read the wonderful books by Marty Brown “Power Supplies” and Semenov “Power Electronics”. As a result, I noticed a lot of errors in circuits from the Internet, and lately all I see is a cruel mockery of my favorite TL494 microcircuit.

I love the TL494 for its versatility; there is probably no power supply that cannot be implemented on it. In this case, I want to look at the implementation of the most interesting half-bridge topology. The control of the half-bridge transistors is done galvanically isolated, this requires a lot of elements, in principle a converter inside a converter. Despite the fact that there are many half-bridge drivers, it is too early to write off the use of a transformer (GDT) as a driver; this method is the most reliable. Bootstrap drivers exploded, but I have not yet seen a GDT explosion. The driver transformer is a regular pulse transformer, calculated using the same formulas as the power transformer, taking into account the drive circuit. Often I have seen the use of high power transistors in GDT drives. The outputs of the microcircuit can produce 200 milliamps of current, and in the case of a well-designed driver, this is a lot; I personally drove the IRF740 and even the IRFP460 at a frequency of 100 kilohertz. Let's look at the diagram of this driver:

T
This scheme switched on to each GDT output winding. The fact is that at the moment of dead time, the primary winding of the transformer is open-circuited, and the secondary windings are not loaded, so the discharge of the gates through the winding itself will take an extremely long time, the introduction of a supporting, discharge resistor will prevent the gate from quickly charging and waste a lot of energy. The diagram in the figure is free from these shortcomings. The edges measured on a real prototype were 160ns rising and 120ns falling on the gate of the IRF740 transistor.

The VD6 diode bridge rectifies the voltage from primary winding and if it exceeds the supply voltage, it will return it back to capacitor C2. This happens due to the appearance of reverse voltage; after all, the inductance of the transformer is not infinite.

The circuit can be powered through a quenching capacitor; currently a 400 volt K73-17 at 1.6 uF is working. diodes KD522 or much better 1n4148, replacement with more powerful 1n4007 is possible. The input bridge can be built on 1n4007 or use a ready-made kts407. On the board, Kts407 was mistakenly used as VD6, it is under no circumstances allowed to be placed there, this bridge must be made with RF diodes. Transistor VT4 can dissipate up to 2 watts of heat, but it plays a purely protective role; you can use KT814. The remaining transistors are KT361, and replacement with low-frequency KT814 is highly undesirable. The tl494 master oscillator is configured here at a frequency of 200 kilohertz, which means that in push-pull mode we get 100 kilohertz. We wind the GDT on a ferrite ring 1-2 centimeters in diameter. Wire 0.2-0.3mm. There should be ten times more turns than the calculated value, this greatly improves the shape of the output signal. The more it is wound, the less you need to load the GDT with resistor R2. I wound 3 windings of 70 turns on a ring with an outer diameter of 18mm. The overestimation of the number of turns and the mandatory loading are associated with the triangular component of the current; it decreases with an increase in turns, and loading simply reduces its percentage influence. The printed circuit board is attached, but it does not quite correspond to the diagram, but the main blocks are there, plus the body kit of one error amplifier has been added and series regulator for power supply from a transformer. The board is made for installation into the section of the power section board.

Car battery for TL494" title="Charger for car battery on TL494"/>

The microcircuit is installed on a small printed circuit board 45 x 40 mm, the remaining elements of the circuit are installed on the base of the device and the radiator.

The wiring diagram for connecting the printed circuit board is shown in the figure below.

The circuit used a rewound TS180 power transformer, but depending on the magnitude of the required output voltages and current, the power of the transformer can be changed. If an output voltage of 15 V and a current of 6 A is sufficient, then a power transformer with a power of 100 W is sufficient. The radiator area can also be reduced to 100...200 cm2. The device can be used as a laboratory power supply with adjustable output current limitation. If the elements are in good working order, the circuit begins to work immediately and only requires adjustment.