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有关数字电源函数PFC_InvRmsSqr

hua liu
Prodigy 250 points


在数字电源的库中有这么一个函数PFC_InvRmsSqr，我看了介绍，但是对于PFC_InvRmsSqr_VminOverVmax:n和PFC_InvRmsSqr_Vmin:n的取值还是不是很明白，能不能请TI的高手在指导一下这两个变量怎么取值，谢谢！

Usage: This section explains how to use this module. The example assumes a PFC
Stage designed for 264VAC to 85VAC and the voltage feedback is designed
for peak 400V. Also, the minimum voltage used in this module is 80Vrms.
Hence,
PFC_InvRmsSqr_VminOverVmax:n: = _IQ30(80/283)=_IQ30(0.283)（怎么这两个都一样呢？283是怎么来的？）
PFC_InvRmsSqr_Vmin:n: =<_IQ24(80/283)=_IQ24(0.283)

 

在后面的应用样例中

PFC_InvRmsSqr_VminOverVmax1=_IQ30(0.3913);
PFC_InvRmsSqr_Vmin1=_IQ24(0.225);他们的值又不是相同的

  • 0
    TI__Expert 3680 points

    这两个值应该是一样的，它代表AC输入电压最小值和最大值的比值。超出这个范围的输入会被钳位。以为这里默认的工作电压范围是264VAC，所以输入信号的最大值要大于264.这里取了283.

    PFC_InvRmsSqr_VminOverVmax:n: is the ratio of minimum over

    maximum voltage, which in this example is 80Vrms/283Vrms. This ratio is

    then represented in Q30 format. The PFC_InvRmsSqr_Vmin:n: is the

    same value represented in Q24 format.

  • 0 回复 Victor Zheng
    Expert 1286 points

    FC_INVSQR_In1=&VacLineAvg;

    PFC_INVSQR_Out1=&InvAvgSqr;

    PFC_INVSQR_VminOverVmax1=_IQ30(0.2807); // 80V/285V

    PFC_INVSQR_Vmin1=_IQ24(0.17868); // 80V

    _IQ30(0.2807)可以理解，_IQ24(0.17868)是怎么通过80V算出来的？