multiplex output power supply
In terms of the power is applied, to the selection of power supply products for the “fool”, that is the choice of power supply voltage as long as the load does not exceed the maximum power, regardless of the system of various load characteristics of how to change, and various power supply voltage is still accurate correct. At this point, the vast majority of multi-channel output power is unsatisfactory. In order to further explain the characteristics of multiplex output power, the block diagram of multi output switch power source is described in Figure 1..
From Figure 1, it can be seen that the real form of closed-loop control is the main circuit Vp, other Vaux2, Vaux1 and other auxiliary circuits are in control of the. From control theory, we know, only VP regardless of the input and output changes (including changes in voltage, load change), under the conditions of the closed-loop feedback control can ensure the accuracy of quite high (generally better than 0.5%), that VP in largely depends only on the reference voltage and sampling rate. For Vaux2, Vaux1, the accuracy of the following aspects mainly depends on:
1) the turn ratio of the T1 main transformer is mainly determined by Np1:Np2 or Np1:Np3
2) the load of the auxiliary circuit.
3) the load of the main circuit.
Note: if the above 3 point set, the impact of the input voltage on the auxiliary circuit has been very limited..
In more than 3 points, as a specific switch power converter, main transformer turns ratio has been set, so the impact auxiliary circuit output voltage accuracy of the largest factors as the main circuit and auxiliary circuit of the load. In the switching power supply products, there are special technical indicators and the power of this feature, that is, the cross load adjustment rate. In order to better relate this problem, the measurement and calculation method of cross load adjustment rate is as follows.
21 power converter multiplex cross load adjustment rate measurement and calculation steps
1) the test gauge and equipment are connected as shown in Figure 2.
2) regulate the power converter input voltage to be measured as the nominal value, closing the switch S1, S2? Sn, adjust the measured power converter output current rating, measuring the output voltage of the j-th road UJ, using the same method measurement other various output voltage.
3) by adjusting the output load current of the various outputs outside of the j path as the minimum, the output voltage of the output voltage of the j is ULj.
4) by type (1) calculate the cross load adjustment rate of J road SIL.
Type: Uj for each other when the current load is minimum, the absolute value of Uj and the ULj output voltage difference;
Uj output current for each of the rated value, the output voltage of J road.
According to the test and the calculation method of the above can cross load adjustment rate and understood as: all other output circuit load step change (100%0%) of the path of output voltage accuracy of the percentage.
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