CN107482919A - Control Method Based on Boost Full Bridge Isolated Converter - Google Patents

Abstract

A kind of control method based on Boost full-bridge isolated converters, the dutycycle D1 and the dutycycle D2 of second switch pipe (S2) and the 3rd switching tube (S3) of first switch pipe (S1) and the 4th switching tube (S4), 0 ＜ D1 ＜ 1, 0 ＜ D2 ＜ 1, and D1 ≠ D2, dutycycle by T switch periods first switch pipe (S1) and the 4th switching tube (S4) is D2, second switch pipe (S2) and the 3rd switching tube (S3) dutycycle are D1, again after T switch periods, the dutycycle of first switch pipe (S1) and the 4th switching tube (S4) reverts to D1, the dutycycle of second switch pipe (S2) and the 3rd switching tube (S3) reverts to D2, move in circles successively.5th switching tube dutycycle is D0,0 ＜ D0 ＜ 1, the sequential of 5th switching tube (S0) changes with the conversion of first switch pipe (S1) and second switch pipe (S2) dutycycle, all the time the complementary conducting of switching tube less with dutycycle in dutycycle D1 and dutycycle D2.

Description

Control Method Based on Boost Full Bridge Isolated Converter

technical field

The invention relates to a control method based on a Boost full-bridge isolation converter.

Background technique

Boost full-bridge isolated converter has the advantages of high-frequency electrical isolation, large output power, high voltage conversion ratio, small input current ripple, and high reliability when the load is short-circuited. It is very suitable for high-voltage output DC conversion applications with isolation requirements.

The control method of the traditional Boost full-bridge isolated converter is as follows: the timing of the first switching tube S1 and the fourth switching tube S4 are consistent, and the duty cycle is D; the timing of the second switching tube S2 and the third switching tube S3 are consistent, and the duty cycle is D. D, and the phase difference between the first switching tube S1 and the second switching tube S2 is 180°, the duty ratio is 0.5<D<1, the fifth switching tube S0 is in the switching tube S1, switching tube S2, switching tube S3 and switching tube S4 off when both are on. This control method makes the switching frequency of the fifth switching tube S0 twice that of the first switching tube S1, which has higher requirements on the switching tube and large losses, especially in high-voltage and high-power applications.

Contents of the invention

In order to overcome the shortcomings of the prior art, the present invention proposes a control method based on a Boost full-bridge isolated converter. The control method of the present invention reduces the switching frequency of the fifth switching tube S0, reduces the conduction time of the switching tube, reduces loss, avoids the problem of unidirectional magnetic bias of the magnetic element, and further improves system reliability.

To achieve the above object, the present invention adopts the following technical solutions:

The control method of the invention sends a driving signal to each switch tube by adjusting the duty cycle and timing sequence of the five switch tubes to realize the action of the switch tube and control the output voltage and output power of the converter.

The Boost full-bridge isolation converter based on the present invention is composed of an H full-bridge, an uncontrolled full-bridge, two support capacitors, a high-frequency transformer, a high-frequency inductor, a clamp capacitor and a fifth switch tube. The H full bridge is composed of the first switching tube, the second switching tube, the third switching tube and the fourth switching tube, the first switching tube and the fourth switching tube have the same timing, the second switching tube and the third switching tube have the same timing, In addition, the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube are turned on at the same time, and the duty cycle of the fifth switch tube is D0, which is compared with the duty cycle of the first switch tube and the second switch tube. The small switches are turned on complementary. The duty cycle of the first switch tube and the fourth switch tube is D1, the duty cycle of the second switch tube and the third switch tube is D2, after T switching cycles, the duty cycle of the first switch tube and the fourth switch tube becomes D2 , the duty cycle of the second switch tube and the third switch tube becomes D1, and after T switching cycles, the duty cycle of the first switch tube and the fourth switch tube returns to D1, and the second switch tube and the third switch tube The duty cycle reverts to D2.

The range of the switching period T is: T>0.

The timing of the fifth switching tube varies with the conversion of the duty ratios of the first switching tube and the second switching tube.

Description of drawings

Figure 1 Boost full bridge isolation converter topology;

Figure 2 Switch tube logic diagram.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the Boost full-bridge isolation converter topology based on the present invention consists of an H full-bridge, an uncontrolled full-bridge, two support capacitors Ci, Co, a high-frequency transformer T, a high-frequency inductor L1 and a clamp The bit capacitor Cc and the fifth switch S0 are formed. The support capacitor Ci is connected to the filter inductor L1, the clamp capacitor Cc is connected in series with the fifth switch tube S0, the support capacitor Ci connected in series with the filter inductor L1 and the clamp capacitor Cc connected in series with the fifth switch tube S0 and H are all The bridges are connected in parallel, the output side of the full bridge H is connected to one side of the high-frequency transformer T, and the other side of the high-frequency transformer T is connected to the uncontrolled full bridge, and finally the output side of the uncontrolled full bridge is connected in parallel with the supporting capacitor Co on the output side to form the existing circuit topology. Among them, the H full bridge is composed of 4 switch tubes S1, S2, S3, S4 with anti-parallel diodes; the uncontrolled full bridge is composed of 4 diodes D1, D2, D3, D4.

The control method of the present invention adjusts the duty cycle and timing of the five switching tubes S0, sends a driving signal to each switch, realizes the action of the switching tubes, and controls the output voltage and output power of the converter.

The logic of the switching tube is shown in Figure 2:

The H full bridge is composed of the first switching tube S1, the second switching tube S2, the third switching tube S3 and the fourth switching tube S4, the first switching tube S1 and the fourth switching tube S4 have the same timing, the second switching tube S2 and the The timing of the three switching tubes S3 is consistent, the first switching tube S1, the second switching tube S2, the third switching tube S3 and the fourth switching tube S4 are turned on at the same time, and the duty cycle of the fifth switching tube S0 is D0, which is the same as the duty cycle D1 and the switching transistor with a smaller duty ratio in the duty ratio D2 are turned on complementary, 0<D0<1.

The duty cycle of the first switching tube S1 and the fourth switching tube S4 is D1, and 0<D1<1, the duty cycle of the second switching tube S2 and the third switching tube S3 is D2, 0<D2<1, after T In the switching cycle, the duty cycle of the first switching tube S1 and the fourth switching tube S4 becomes D2, the duty cycle of the second switching tube S2 and the third switching tube S3 becomes D1, and after T switching cycles, the first switching tube The duty cycle of S1 and the fourth switching tube S4 is restored to D1, the duty cycle of the second switching tube S2 and the third switching tube S3 is restored to D2, T>0; the timing of the fifth switching tube S0 follows that of the first switching tube S1 It changes with the change of the duty cycle of the second switch tube S2, and is always complementary to the switch tube with a small duty cycle.

Compared with the traditional control method, the present invention reduces the switching frequency of the fifth switching tube S0, reduces the conduction time of the switching tube, reduces the loss, avoids the problem of unidirectional magnetic bias of the magnetic element, and further improves the reliability of the system. sex.

Claims (3)

1. a kind of control method based on Boost full-bridge isolated converters, the Boost full-bridges isolated converter being based on is by one H full-bridge, a uncontrollable rectifier full-bridge, the 5th switching tube (S0), clamp capacitor (Cc), two Support Capacitors (Ci, Co) and filtering Inductance (L1) is formed, and H full-bridge is made up of 4 switching tubes with anti-paralleled diode, and respectively first switch pipe (S1), second open Pipe (S2), the 3rd switching tube (S3) and the 4th switching tube (S4) are closed, the 5th switching tube (S0) is by the switch with anti-paralleled diode Pipe forms, and first switch pipe (S1) is consistent with the 4th switching tube (S4) sequential, second switch pipe (S2) and the 3rd switching tube (S3) Sequential is consistent, and first switch pipe (S1), second switch pipe (S2), the 3rd switching tube (S3) and the 4th switching tube (S4) are led simultaneously Logical, first switch pipe (S1) dutycycle and second switch pipe (S2) dutycycle are unequal；5th switching tube (S0) dutycycle is D0, Turned on less that switching tube complementation of dutycycle in first switch pipe (S1) and second switch pipe (S2),

It is characterized in that：Described control method is, first switch pipe (S1) and the 4th switching tube (S4) dutycycle are D1, second Switching tube (S2) and the 3rd switching tube (S3) dutycycle are D2, are switched by T switch periods first switch pipe (S1) and the 4th Pipe (S4) dutycycle is changed into D2, and second switch pipe (S2) and the 3rd switching tube (S3) dutycycle are changed into D1, then by T switch week After phase, first switch pipe (S1) and the 4th switching tube (S4) dutycycle revert to D1, second switch pipe (S2) and the 3rd switching tube (S3) dutycycle reverts to D2.

2. the control method as claimed in claim 1 based on Boost full-bridge isolated converters, it is characterised in that：Described opens It is T ＞ 0 to close cycle T scope.

3. the control method as claimed in claim 1 based on Boost full-bridge isolated converters, it is characterised in that：Described The sequential of five switching tubes (S0) changes with the conversion of first switch pipe (S1) and second switch pipe (S2) dutycycle.