M8V6电子负载，单管250W烤鸡中。。。

100MHZ

yibin0092 发表于 2014-11-10 08:29
管子烧了没有?还没有烧吗?

没烧啊

xp0520

请教下楼主，面板怎做的，外包给别人做吗，如果自己D 点东西，一次做十片左右，成本多少？

100MHZ

xp0520 发表于 2014-11-18 17:23
请教下楼主，面板怎做的，外包给别人做吗，如果自己D 点东西，一次做十片左右，成本多少？

发coredraw文件给我

xp0520

100MHZ 发表于 2014-11-18 19:29
发coredraw文件给我

如图，上图我是用打印机打的纸的，如做成塑料的？ 尺寸大概360*60 mm  , 没CAD档，自己用PCB软件画的

100MHZ

xp0520 发表于 2014-11-18 19:59
如图，上图我是用打印机打的纸的，如做成塑料的？ 尺寸大概360*60 mm  , 没CAD档，自己用PCB软件画的 ...

你看看能不能转dxf

cnit

这个外壳现在有卖不？

其实可以考虑一下机壳延长一下，可以放更大的散热器

kirich

100MHZ 发表于 2014-8-12 20:58
IXFB100N50P
这是智育购买了多次试验后才挖掘出来的适合DIY的大功率管子；
注意高温的时候不可以超过50 ...

Hello.
Help me please.
How did you get the opportunity to load current over 5 Amperes.
I have a setup with an increase of more than 5 amps of current board does not do anything. It does not set the current more than 5 amps while the power LED displays and 10 amps and 15 amps.
You have used the original firmware or modify it? I have a board with such a display as you (2004), can help me with the firmware under 15 or 30 amp extension?

I have tried to describe your problem in the subject - M8单片机恒流型数字电子负载

Regards Andrew.

kirich

Here is my attempt to describe the problem -
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
I forgot I was in some photos and descriptions see that the M8 has an electronic load calibration mode.
Turns on a long press of a button. I have this mode is not switched on at all, the button works.
By clicking on the button I can simply expressed mode and set the current value.
So it should be?

yangfei1980

kirich 发表于 2014-12-29 07:26
Here is my attempt to describe the problem -
I'll try to explain once again.
No problems getting ...

修改电流取样电阻。5A是0.05Ω 15A是0.015Ω。您电流取样电阻套件里面是按照5A电流配置的。固件支持15A，但是电流取样电阻在5A电流以上时候端电压超过了0.25V，所以调节没有反应。

kirich

Thanks for the reply.
I plan to apply this scheme to increase the current (top right stage 2).
But as the processor know that I have added transistors, and will be adjusted PWM full range of 0-15 amps.
After all, if I add additional transistors, the resistors 53 and 54 will have to leave with the same resistance.
The voltage at terminal 5 U51B remain unchanged.
How does this work?