The article details a PWM speed controller circuit for a fan air blower system to be used in Biomass cook stoves. The circuit also includes an uninterrupted automatic battery back-up supply with an integrated automatic battery charger circuit for the particular application. The idea was requested by Mr. Tushar and Sivaranjani.
Technical Specifications
谢谢你的兴趣和热情的反应。为了给你一个想法，我们正在研究生物量烹饪炉灶，这是对LPG气缸和传统的柴火烹饪的替代品。基本上应用通过推动炉灶燃烧系统中的更多空气，确保清洁燃烧，减少室内空气污染。
In-order to facilitate more air into the system, these cook stoves have
1) a PMDC motor (Brush) - 12VDC with an RPM of 7000, 40 W,0.53 A
2）安装在电动机轴上的叶轮以通过系统在空气中发送
3）有一个7.2 AH密封的铅酸电池，提供备用电源以运行系统。
As mentioned earlier we would need a circuit that would have
1) PWM Speed controller for a 12VDC motor which would in turn regulate the amount of air entering the system
2) A 12 V Lead acid battery charger
3) transformerless Power supply
We would like to share experiences we have faced till date on the circuits and have been really clueless on how to solve them.
1) They are put to maximum misuse by the cooks in the kitchen. Hence a simple but a rugged system needs to be in place
2) Power supply side
a）由于我们的主要目标地区是泰米尔纳德邦，我们有一个可怕的电力危机，因此在降压电源和电池电源之间切换应该是自动的，而不是波动的操作电压
b) If the battery has not been in use for more than a month, the entire circuit stops working
3）PWM侧
a) Fine regulation of motor speed, to give a feel of use similar to that of an LPG stove. What we observed is that after 16 hours of continuous operations there is no speed variation in the motor. Haven't been able to pinpoint the reason yet.
4) General Conditions
a) since this circuit will be operating near a furnace and inspite of the fact that it is well ventilated and insulated from the heat, the circuit itself gets heated considerably and many claim that the circuit fails due to this reason.
We would like to come up with a solution with your expertise to tackle these problems and help us in our sustainable livelihoods venture.
如果您有任何疑问，请告诉我们，我们如何进一步掌握。
Regards,
Sivaranjani.
The Design
根据要求，生物质烹饪炉灶应用需要12 V风扇用于将空气迫使空气进入燃烧室，以获得所需的改进的结果，这种空气诱导需要变化，这意味着风扇速度应通过PWM控制旋钮具有可控特征，该用户可以用于设置/选择所需的空气感应和燃烧速率。
新颖的12 V PWM风扇速度控制电路如下所示，使用几个IC 555。
Using Two IC 555 for the PWM Fan Control
IC1用于产生80 Hz平方波频率，该波频被施加在布置为PWM发生器的IC2的Pin2处。IC2在其PIN3处通过首先将输入PIN2方波输入到C3的三角波中，然后通过将其与施加在其PIN5处施加的电压电平的电压水平进行比较来产生变量PWM。
The pin5 voltage which is manually selectable or adjustable via pot determines the duty cycle of the PWMs which in turn determines the connected fan speed accordingly.
The variable voltage or the adjustable PWM pot is formed by P1, along with T2 rigged in the common collector mode.
上述说明的风扇速度控制器需要通过不间断电源系统供电，从备用良好的充电电池备份阶段。
The battery in turn requires an automatic battery charger circuit so that it stays ready for providing an instant uninterrupted power to the fan, ensuring a smooth and a continuous supply to the motor and feed of air to the biomass cook stove.
采用基于OPMAP的自动电池充电器电路
All these conditions are fulfilled in the following circuit diagram which is an opamp based automatic battery charger circuit.
充电器电路如下所示使用couple of opamps for the required detection and cut-off during the battery full and battery low level thresholds.
连接在左741CIC的PIN3处的10K预设使得每当电池达到完全电荷水平时，IC的输出就会高度停用相关的TIP127，将充电电压切断到电池。
The glowing LED indicates charging ON situation of the battery and vice versa.
右手侧IC 741级定位用于监视电池的低电压状态。当它到达较低阈值时，IC的PIN2变得低于参考PIN3，这又导致IC的输出高温停用附加的尖端127。
The load now is inhibited from getting any power from the battery.This threshold cut off is set by adjusting the 10k preset at pin2 of the IC
这里也是基础LED指示相关情况，发光表示电池低，而关闭表示电池在较低阈值上方。
为什么使用两种二极管
The two diodes are connected with a specific purpose, while the mains is present the 14V supply from the SMPS being slightly higher than battery voltage keeps the horizontal diode reverse biased and allows only the SMPS voltage to reach the load or the fan blower via the vertical 1N5402 diode.
In case when mains voltage fails, the horizontal diode connected at the collector of the right hand side TIP127 quickly gets forward biased replacing the dead SMPS supply with the battery supply, ensuring an uninterrupted flow of the supply to the fan.
14V无变压器的SMPS可以购买从市场制作或个人建造。以下链路中可以看到一些合适的电路：
12 V SMPS using TNY tiny switch IC
需要在其输出阶段调整以上所有型号，以获取所需的14 V.
你好Swagatam。当我看到第二次电路时，我很开心。我已经完成了它，只有我修改它在36V DC上工作，只能在消耗电流。我用具有15个放大器输入的镜面二极管取代了1N5402二极管，但它总是变热和燃烧。如果它将被替换为12V 40AMP继电器，我在想。将水平线连接到n / o和垂直线到n / c。我需要你的建议或更好的方法来实现它。我将从第一个IC的PIN7收集继电器供应。
你好AFAM，
是的，您可以在输出中使用继电器进行控制，但对于IC741，36V太高，您需要将其放入12V，使用7812 IC，以馈送741 IC的PIN7，否则这些都会瞬间炸并停止工作
先生，我再次回来了。我迫切需要你的帮助。我需要一个可以处理19AMP，27V DC电机的前进/反向偏置二极管。1N5402无法做到.Kindly列出了两种或三个这样的二极管。我用继电器来更换垂直和水平1n5402，但它令人沮丧。谢谢。
Afam, if the load is 19amp then I think the back emf would also be close to this value, in that case you would require a 20amp diode across it…Google 20amp diode you'll be able to find the options, or may be you can try a high value capacitor instead.
这对我很有帮助。
您能否将我指向商业现成的控制器可用于在线购买？我也是在这里获得相同的目的，寻找一个现成的控制器到发电的生物量炉，需要两个12V风扇和设置相同。
I am glad you liked my site, however I am sorry I have no knowledge regarding any commercial manufacturer in this field….