Three-phase asynchronous motor current sampling resistance of three

AC induction cooling fan motor 
Specifications
1.Customised 
2. good quality 
3. 20 years manufacturing experience 


The selection of the sampling resistance is according to the scope of the power of the servo drive, select the appropriate value. Sampling resistance is larger, can use the HCPL - 7840 the entire input range, so as motor vehicle spare parts to improve the accuracy of sampling circuit, but too much resistance may cause problems: on the one hand can collect current range is too small, can't show the maximum output of the power device capacity; On the other hand, the larger value can make the sampling resistor on the power loss is www.facebook.com/dongfeng.motor bigger, bring serious fever, which affects the precision of resistance and temperature coefficient of nonlinear, even burned sampling resistance; On the other hand, the sampling resistance is small, while it is possible to improve the ability of sampling circuit of sampling, collected larger electric current, but too small sampling resistance will make the sampling resistance on the output voltage is reduced.


so as to make the error offset and interference noise in the signal amplitude proportion is too large, reduce the sampling accuracy. Therefore, sampling resistance is generally calculate divide the input voltage ac motor of the recommended by work normally through fan motor the peak current sampling resistor, then multiplied by a margin of about 0.8 ~ 0.9 coefficient. In order to improve the quickness and the sensitivity of sampling circuit, sampling resistor with smaller inductance value. Small temperature coefficient, can avoid resistance heating effect the precision of sampling; In order to improve the precision of sampling resistance and scattered power loss to reduce fever, can consider to put several precision sampling resistor in parallel or in series to offset the positive and negative error to improve the precision of resistance value.