外文翻译-使用时间保持控制反激式DC-DC变换器漏感效应的分析.doc

1、英文原文Analysis of Leakage-Inductance Effect in a Flyback DC-DC Converter Using Time Keeping ControlHiroto Terashi, Tarnotsu NinomiyaAbstract-Flyback DC-DC converter is often used as power supply for many electronic systems because of circuit simplicity. We have already presented novel flyback DC-DC co

2、nverter with improved stability (time keeping controlled flyback converter) by using the technique of keeping inductor current constant 3.This converter behaves as like forward converter without RWZ (Right Half Plane Zero), therefore the frequency bandwidth of open-loop transfer function from duty r

3、atio to output voltage is wider than conventional flyback converter due to disappearing of RHPZ.In this paper we report the static and dynamic analysis about this novel flyback converter witb leakage inductance, which become larger in case of a few turn 01 secondary winding especially. The analysis

4、method is selected with state space averaging method because of obtaining the symbolical solution. The number of state is 5 including the period regarding leakage inductances of primary and secondary stages. According to the results the theoretical data with state space averaging method agree with t

5、he experimental one and also the theoretical date with sampled-data method well. And it is confirmed that the leakage inductances act as an equivalent resistance and that static load regulation is deteriorated, hut the dynamic response is smoothed due to the increased dumping factor.I CIRCUIT TOPOLO

6、GY AND BASICO PERATIONFig.1 shows a novel flyback converter topology, which has the period of keeping a transformer current constant. Basic schematics are in Fig.1 (a) and Fig.1 (b) that will be explained the operation from now is used as the experimental circuit.Fig.2 shows the key waveforms in the

7、 time sequence of gate drive voltages for main switches, primary, secondary and magnetizing currents in the transformer, and transformer voltage.Fig.1. Circuit topology of the proposed flyback convertFig.2. Key waveforms of the proposed flyback converterIn state1, at first the both switches Q1, and

8、Q2 are turned ON. Then, the remaining secondary current decreases gradually and primary current increase at the same time and the same rate due to leakage inductance.In state2, when secondary current reaches to zero, primary current continues to increase with smaller slope than State1.In state3, onl

9、y switch Q2 is turned OFF and the energy is kept to be the same value just before the switch Q2 was turned OFF.In state4, the switch Q1 is turned OFF, then the primary current decreases gradually and secondary current in the transformer increases opposite to State1. Finally, the primary current beco

10、mes zero.In state5, the stored energy in primary inductance of transformer is transferred to secondary side.The sum of duty cycle in state4 and 5 can be defined as P .The P has some constant value less than 1 and is selected as 0.5 in Fig.2, which represents the key waveforms in this schematics. The

11、 duty ratio of each state is shown by dy1, dy2, dy3, dy4, dy5. The duty ratio D is the sum of duty in state1 and 2, which should be controlled.II ANALYSIS OF CHARACTERISTICSFig.3 shows each state of equivalent circuits in Fig.1. It is noted that the polarity of input voltage Vin is opposite for stat

12、e1 and 4. Therefore the rising and falling slopes of primary current are different in both commutation periods. The component symbols and parameters, which are represented in Fig.1 and 3, are defined as follows;L Magnetizing inductanceRL Load resistanceR Reflected RL from primary to secondaryCO Outp

13、ut capacitorC Reflected CO from primary to secondaryK Coupling coefficient of the transformerT Switching periodFig.3. The equivalent circuit of Each stateA Transformer with Leakage InductanceA-1. Average State Space EquationThe magnetizing current im, and output voltage vo is selected as two state s

14、pace variables. The dy1, and dy4 are the duty ratio called commutation period in state1 and 4 respectively. And the duty ratio o f P which is constant and that of D which should be controlled are shown in expression (1) as you can see in Fig.2. The use of both P and D allows the duty ratio of dy5, a

15、nd dy2, to be eliminated. (1)The state space equations regarding im and vo is derived from sum of “volt-second product” and “current-second product” respectively as in (2). Regarding dy1, dy4 , the expression (3) can he obtained using the characteristic of state space averaging method. The hat mark

16、over the symbol like and means “averaging”. The P , which is sum of duty in state4 and 5, is the period of energy transferring to secondary side. And it is chosen as less than 1. P is selected as 0.5 in Fig.2. (2) (3)If the coupling coefficient k is close to unity, the equations (11) and (12) can be simplified as in (4) and (5).