PFC
哪位大哥有用过L6561 transient mode controller, 现在我碰到振荡问题无法解决,可以指点一下怎样去调compensation for feedback ?Thank you very much .
PFC
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@cxzcjz
几种方法几种方法,仅供参考.1.调节反馈增益.2.过零检测端对地加小电容.3.过零检测端加偏置.4.如间歇振荡,可提高动态速度,如8-4加电阻.5.注意电压取样反馈线
6561
Thanks a lot, I tried to debug compensation, but no more help, I checkd the ZCD, no any abnormal. the problem occured at higher power output power, the ripple of buld cap occured little step follow the sinusoid waveform. did you meet this problem, yes, I will try according as your second idea, thanks a lot.
Thanks a lot, I tried to debug compensation, but no more help, I checkd the ZCD, no any abnormal. the problem occured at higher power output power, the ripple of buld cap occured little step follow the sinusoid waveform. did you meet this problem, yes, I will try according as your second idea, thanks a lot.
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@cxzcjz
几种方法几种方法,仅供参考.1.调节反馈增益.2.过零检测端对地加小电容.3.过零检测端加偏置.4.如间歇振荡,可提高动态速度,如8-4加电阻.5.注意电压取样反馈线
compensation
Could you explain for the 20Hz bandwidth for the feedback compensation, theoretic, it will improve power factor, so the cap of feedback compensation need to use bigger, but I found it will cause unsatable, do you have some idea?
Could you explain for the 20Hz bandwidth for the feedback compensation, theoretic, it will improve power factor, so the cap of feedback compensation need to use bigger, but I found it will cause unsatable, do you have some idea?
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@arthur.deng
compensationCouldyouexplainforthe20Hzbandwidthforthefeedbackcompensation,theoretic,itwillimprovepowerfactor,sothecapoffeedbackcompensationneedtousebigger,butIfounditwillcauseunsatable,doyouhavesomeidea?
About compensation
1、因为PFC的输出产生2培的工频的纹波(100HZ),假如带宽太高的话,反馈部分就会企图去调节纹波,如果这样的话
功率因数必然减低.这个带宽的选择有点类似开关电源的截止频率通常设计在开关频率的五分之一左右是一个道理.
2、如果反馈电容太大的话,也就是带宽会更低,如果在稳态情况下工作,功率因数是会提高,但是由于实际工作情况下很多参数都是在变化的,且反馈电容增大的话,会影响系统的响应速度变慢,这样的话必然会影起振荡.
3、我想问你一个问题,不知你是否测过电感上的电流?我也曾经用过L6561,我发现它并非理论上所说的临界导电模式,电感上电流根本就没有接近零点,而有点象连续导电模式.实际可以和理论偏差,但是这个偏差也有点太大了,如果有哪位老大也用过L6561的话,麻烦你们测一下电感上的电流,小弟期待着你们的结果.
1、因为PFC的输出产生2培的工频的纹波(100HZ),假如带宽太高的话,反馈部分就会企图去调节纹波,如果这样的话
功率因数必然减低.这个带宽的选择有点类似开关电源的截止频率通常设计在开关频率的五分之一左右是一个道理.
2、如果反馈电容太大的话,也就是带宽会更低,如果在稳态情况下工作,功率因数是会提高,但是由于实际工作情况下很多参数都是在变化的,且反馈电容增大的话,会影响系统的响应速度变慢,这样的话必然会影起振荡.
3、我想问你一个问题,不知你是否测过电感上的电流?我也曾经用过L6561,我发现它并非理论上所说的临界导电模式,电感上电流根本就没有接近零点,而有点象连续导电模式.实际可以和理论偏差,但是这个偏差也有点太大了,如果有哪位老大也用过L6561的话,麻烦你们测一下电感上的电流,小弟期待着你们的结果.
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@darkhorse96
Aboutcompensation1、因为PFC的输出产生2培的工频的纹波(100HZ),假如带宽太高的话,反馈部分就会企图去调节纹波,如果这样的话功率因数必然减低.这个带宽的选择有点类似开关电源的截止频率通常设计在开关频率的五分之一左右是一个道理.2、如果反馈电容太大的话,也就是带宽会更低,如果在稳态情况下工作,功率因数是会提高,但是由于实际工作情况下很多参数都是在变化的,且反馈电容增大的话,会影响系统的响应速度变慢,这样的话必然会影起振荡.3、我想问你一个问题,不知你是否测过电感上的电流?我也曾经用过L6561,我发现它并非理论上所说的临界导电模式,电感上电流根本就没有接近零点,而有点象连续导电模式.实际可以和理论偏差,但是这个偏差也有点太大了,如果有哪位老大也用过L6561的话,麻烦你们测一下电感上的电流,小弟期待着你们的结果.
about compensation
Thanks a lot! You are right! Very glad to meet you! I solved the problem, it is not cause by the compensation, in fact, the compensation of L6561 is easy to design, no more problem, for my problem, because the output power is 240W, so I design in DCM is a challenge for us and D/D is design by flyback, this two challenges for us, maybe for all the power design, but I am successful. Just now, I found the root cause, it caused by the MOS driver circuit, because L6561 only can provide 700mA source and sink current, this is difficult to driver the general MOSFET for higher power output, even design a totem pole driver circuit, so I changed to CoolMOS of infineon, all are OK, by the way, the VCC is not used too high, it will cause this problem, because the turn off time will be very longer, more need to notice, the Vcc of PFC and Vcc of D/D is better to separated from the winding of main transformer by two diode, for your concern, the ZCD is not a good, of cource, we can\'t do a really idealist in the actual design because there have more parasitical element we can not consider....any way, this technique only is tended to improve efficiency, if the efficiency can be accepted, I thought this problem is not a issue, do you think so? Thank you again, I would like to recognize you. My e_mail address is arthur_deng@apitech. com. tw. you are welcome .
Thanks a lot! You are right! Very glad to meet you! I solved the problem, it is not cause by the compensation, in fact, the compensation of L6561 is easy to design, no more problem, for my problem, because the output power is 240W, so I design in DCM is a challenge for us and D/D is design by flyback, this two challenges for us, maybe for all the power design, but I am successful. Just now, I found the root cause, it caused by the MOS driver circuit, because L6561 only can provide 700mA source and sink current, this is difficult to driver the general MOSFET for higher power output, even design a totem pole driver circuit, so I changed to CoolMOS of infineon, all are OK, by the way, the VCC is not used too high, it will cause this problem, because the turn off time will be very longer, more need to notice, the Vcc of PFC and Vcc of D/D is better to separated from the winding of main transformer by two diode, for your concern, the ZCD is not a good, of cource, we can\'t do a really idealist in the actual design because there have more parasitical element we can not consider....any way, this technique only is tended to improve efficiency, if the efficiency can be accepted, I thought this problem is not a issue, do you think so? Thank you again, I would like to recognize you. My e_mail address is arthur_deng@apitech. com. tw. you are welcome .
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