Scheme of a smooth regulator for a car heater. Powerful PWM regulator

This button accordion has been known to everyone for a long time, they just perform it differently. For many this will seem inconvenient, but for me the goal (minimum rework and parts) has been achieved. Owners of cars of the classic VAZ 2101-2107 model know that the control of the rotation speed of the heater motor is useless and are modifying it in every possible way (I saw and installed a nine motor under the hood, although this is probably not news to many). And I decided to keep up with this trend.

My father-in-law's car was damaged.

The resistor highlighted in red is not needed, because I wanted to use it for indication, but did not use it.

Components

It all works as follows: Power is supplied from the switch (J1) to the voltage stabilizer, having previously smoothed out the ripples with a 25V 470 µF condenser (C1), from the stabilizer (DA1) 7805 the 5V voltage powers our controller (DD1 Tiny13). The controller generates PWM with a frequency of 40 KHz (at this frequency it was possible to achieve silent operation of the motor).

The pulse is fed through a 100 ohm limiting resistor R2 directly to the Gate of the field switch IRF640 (N channel), the source of the field switch is pulled up to the gate potential by a 1 kohm resistor R3 for reliable closing.

Since the maximum current of the motor is 3A (according to dsh at 5V Gate-Source), the field driver draws a little more than 5A and at a frequency of 40 KHz they do not heat up, which completely satisfies me, that’s why there is no driver in front of the field drivers. Although it is correct that it is needed at least for bipolar patients. And we remove our PWM on the motor from the Field Worker.

The signal to increase and decrease PWM is supplied through the KT817(NPN) transistor switch to the MK port. To protect the field switches from the induction of the motor, a reverse diode was installed (crimped) in front of the motor.

Diode with reverse current 10A.

PWM frequency

You also need a diode as the anode to But in and the cathode at +12V to maintain power.

The device works as follows:

• 1.When turned on for the first time, the motor spins up to maximum speed and decreases to the value that remained after turning off in the EPROM, but not lower than 30%. (This was done to be sure that at the minimum duty cycle the motor will spin if condensate is frozen to it (precisely according to This is why my thermostat burned out on the rheostat of the Priora stove) or something similar)).
• 2. By moving the switch to the second position, the PWM duty cycle gradually increases, as soon as the desired speed is achieved, press the button to the first position and the current duty cycle is saved in the Eprom.

If you need to reduce the PWM, repeat step 2.

A short video.

And who is trying to make an equivalent craft using an analogue, on a 555 timer.

All elements are marked.

The strangest thing is that the frequency is 9.6 MHz/4 = 2.4 MHz. Timer divider 1 = 2.4 MHz. Divider by 8 is disabled in fuses. But often it turned out the same as on the multimeter. The multimeter doesn't lie, I checked it with a generator.

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