乌克兰网友DIY的M8V7数字电源

作者： kirich

If anyone is interested, here is my version of the implementation of the instrument.
Current up to 15 Amps (can somebody share firmware of up to 30 amps).
Maximum power of 400 watts.

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I’ll try to explain once again.
No problems getting the output current of 15 amperes.
If I add two gain stage current, the current will be 15 amperes.
But when you install the current, the indicator will be displayed only 0-5Amper.
When you change the current in the range of 5-15 amps, the processor does not change the output, since the PWM output PWM is already 100%.
The problem occurs when you set up the necessary current.

Set current    PWM (PWMA)    Voltage op amp comparison
On display    On pin PB1 MCU       Pin 3 U51A (LM358)
0.000As          0%                               0 V
1.000As          20%                               0.05 V
2.000As          40%                               0.10 V
3.000As          60%                               0.15 V
4.000As          80%                               0.20 V
5.000As          100%                            0.25 V
6.000As          100%                            0.25 V
15.000As       100%                            0.25 V

Even if I add the gain of the current (as in the diagram above), then I get 15 Amps current. But I have to display the current will be less than 3 times, because the change occurs only in the range of adjustment 0-5Amper all.

Adjusting the PWM and the input voltage of the operational amplifier should look like –

Set current    PWM (PWMA)    Voltage op amp comparison
On display    On pin PB1 MCU       Pin 3 U51A (LM358)
0.000As          0%                               0 V
3.000As          20%                               0.05 V
6.000As          40%                               0.10 V
9.000As          60%                               0.15 V
12.000As       80%                               0.20 V
15.000As       100%                            0.25 V
Then the adjustment range is fully used.
,,

In a range of settings (no measurement) 5-15 Ampere current MCU does not change anything on pin PWMA (PB1).

If the adjustment range was up to 30 amps, it would look like this –
Set current    PWM (PWMA)    Voltage op amp comparison
On display    On pin PB1 MCU       Pin 3 U51A (LM358)
0.000As          0%                               0 V
6.000As          20%                               0.05 V
12.000As       40%                               0.10 V
18.000As       60%                               0.15 V
24.000As       80%                               0.20 V
30.000As       100%                            0.25 V

The voltage at the pin 3 of the operational amplifier is used to compare the voltage at the current measuring resistor.
If I add additional transistors as the scheme, I have a 3-fold increase in the output current, but it will be three times larger than the set. When installing additional transistors will be so –
Set current    output current
on display       really
1.000As             3.000 Amp
2.000As             6.000 Amp
3.000As             9.000 Amp
4.000As             12.000 Amp
5.000As             15.000 Amp
6.000As             15.000 Amp
15.000As          15.000 Amp

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