TWI745729B - Full-bridge resonant conversion circuit - Google Patents

Abstract

A full-bridge resonant conversion circuit includes a full-bridge rectifier unit, a resonant unit, a first transformer, a second transformer, and a synchronous rectifier unit. The full-bridge rectifier unit includes a first connection terminal and a second connection terminal. The resonant unit includes a first resonant inductor, a resonant capacitor, and a second resonant inductor. The resonant capacitor is connected in series with the first resonant inductor or the second resonant inductor. The second resonant inductor, the first transformer includes a first primary winding and a first secondary winding connected in series to the first resonant inductor, and the second transformer includes a first primary winding in series with the first primary winding and connected to the second resonant The second primary winding of the inductor and a second secondary winding connected in parallel with the first secondary winding, and the synchronous rectification unit connects the first secondary winding and the second secondary winding.

Description

Full-bridge resonant conversion circuit

The invention relates to a full-bridge resonant conversion circuit, in particular to a full-bridge resonant conversion circuit implemented by dual transformers.

According to the investigation, Chinese invention patent cases CN 106329940A, CN 103595259B and Chinese utility model patent cases CN 206341145U respectively disclose resonant conversion circuits implemented with dual transformers. However, when the LLC resonant circuit used in the aforementioned patent has different power input paths, it will cause a phase difference in the secondary of the dual transformer connected to the back end, making it difficult to control the secondary circuit of the dual transformer. In addition, the circuit disclosed in the current patent further causes high-frequency oscillations in the secondary of the dual transformer, and the electronic components connected to the subsequent stage of the dual transformer need to have higher withstand voltage conditions, resulting in increased development costs.

The main purpose of the present invention is to solve the problem that the conventional circuit is easy to cause the phase difference and high frequency oscillation of the transformer secondary.

To achieve the above objective, the present invention provides a full-bridge resonant converter circuit, which includes a full-bridge rectifier unit, a resonant unit, a first transformer, a second transformer, and a synchronous rectifier unit. The full-bridge rectifier unit includes a first connection terminal and a second connection terminal. The resonant unit includes a first resonant inductor, a resonant capacitor, and a second resonant inductor. The resonant capacitor is connected in series with the first resonant inductor or the second resonant inductor. The second resonant inductor, the first transformer includes a first primary winding connected in series with the first resonant inductor and a first secondary winding magnetically coupled with the first primary winding, and the second transformer includes a first primary winding connected to the first primary winding. A primary winding is connected in series and connected to the second primary winding of the second resonant inductor that is not connected to the end of the resonant capacitor, and a second primary winding that is magnetically coupled to the second primary winding and connected in parallel to the first secondary winding Two secondary windings, the synchronous rectification unit connects the first secondary winding and the second secondary winding, wherein the magnetic circuit distance from the first resonant inductance to the second primary winding and the second resonant inductance to the first The magnetic circuit distance of the primary winding is the same.

In one embodiment, the first secondary winding includes a first sub winding, a second sub winding connected to the first sub winding, a first output terminal connected to the first sub winding, and a second sub winding connected to the second sub winding. The second output terminal of the sub-winding, a first tap output terminal connected between the first sub-winding and the second sub-winding, the second secondary winding includes a third sub-winding, and the third sub-winding The fourth sub-winding connected to the winding, one connected to the third output end of the third sub-winding, one connected to the fourth output end of the fourth sub-winding, and one connected between the third sub-winding and the fourth sub-winding And a second tap output terminal connected to the first tap output terminal.

In an embodiment, the polarities of the first sub-winding and the second sub-winding are the same as the polarity of the first primary winding, and the polarities of the third sub-winding and the fourth sub-winding are the same as the polarity of the second primary winding .

In one embodiment, the full-bridge rectifier unit includes a first bridge arm and a second bridge arm, the first bridge arm includes a first switch and a second switch connected in series with the first switch, the first switch The first connection terminal is formed between the second switch and the second bridge arm includes a third switch and a fourth switch connected in series with the third switch. The third switch and the fourth switch form the The second connection terminal.

In one embodiment, the synchronous rectification unit includes a power reference (GND), a power output terminal connected to the first tap output terminal and the second tap output terminal, and a fifth power reference terminal connected to the first output terminal and the power reference. The switches include a sixth switch connecting the second output terminal and the power reference, a seventh switch connecting the third output terminal and the power reference, and an eighth switch connecting the fourth output terminal and the power reference.

In an embodiment, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch, and the eighth switch are respectively a metal oxide half field Effective transistor.

In one embodiment, the synchronous rectification unit includes at least one capacitor connecting the power output terminal and the power reference.

Through the foregoing implementation of the present invention, compared with conventional ones, the resonant unit of the present invention adopts a symmetrical arrangement of the first resonant inductance and the second resonant inductance, so that the electric power is either from the first connection terminal or the second connection. Terminal enters, the hysteresis of the first transformer and the second transformer are the same, so that the output of the first transformer and the second transformer will not have a phase difference, so that the control of the synchronous rectification unit can be optimized, and then Improve the overall efficiency of the full-bridge resonant conversion circuit. In addition, the circuit of the present invention reduces the high-frequency oscillation of the series circuit of the first secondary winding and the second secondary winding, and reduces the surge generated at the moment of conduction of the switch to which the synchronous rectification unit belongs, so that the synchronous rectification The withstand voltage condition of the switch to which the unit belongs is reduced.

10: Full-bridge resonant conversion circuit

11: Full bridge rectifier unit

111: first connection end

112: second connection end

113: first bridge arm

114: second bridge arm

115: first switch

116: second switch

117: The third switch

118: fourth switch

12: Resonant unit

121: The first resonant inductor

122: resonant capacitor

123: second resonant inductor

13: The first transformer

131: first primary winding

132: first secondary winding

133: first sub winding

134: second sub winding

135: First output

136: second output

137: First tap output

14: The second transformer

141: second primary winding

142: second secondary winding

143: third sub winding

144: The fourth sub winding

145: Third output

146: Fourth output

147: The second tap output

15: Synchronous rectifier unit

151: Electricity Benchmark

152: Power output

153: Fifth switch

154: Sixth Switch

155: Seventh switch

156: Eighth Switch

157: Capacitor

Fig. 1 is a schematic circuit diagram of an embodiment of the present invention.

Fig. 2 is a schematic circuit diagram of another embodiment of the present invention.

Fig. 3 is a schematic diagram of the working waveform of the switch arranged on the secondary side of the transformer according to the present invention.

Figure 4 is a schematic diagram of the operating waveforms of the conventional switches on the secondary side of the transformer.

The detailed description and technical content of the present invention are described as follows in conjunction with the drawings: Please refer to FIG. 1. The present invention provides a full-bridge resonant conversion circuit 10, which can be used in a power supply or a vehicle Power system, where the power supply can It is the ATX specification power supply used by the general public, the power supply used by the server, or the industrial power supply. Furthermore, the full-bridge resonant conversion circuit 10 includes a full-bridge rectifier unit 11, a resonant unit 12, a first transformer 13, a second transformer 14 and a synchronous rectifier unit 15. Wherein, the full-bridge rectifier unit 11 is used as a part of the full-bridge resonant conversion circuit 10 and an external power connection. After the external power enters the full-bridge rectifier unit 11, it will be rectified to provide a back-end circuit (such as the resonant unit 12) . Furthermore, the full-bridge rectifier unit 11 includes a first connection terminal 111 and a second connection terminal 112. It should be understood that the first connection terminal 111 and the second connection terminal 112 referred to herein do not refer to the full-bridge rectifier unit 11 The part used to connect the external power. The full-bridge rectifier unit 11 will output power through the first connection terminal 111 or the second connection terminal 112 according to control. Specifically, in one embodiment, the full-bridge rectifier unit 11 includes a first bridge arm 113 And a second bridge arm 114. The first bridge arm 113 includes a first switch 115 and a second switch 116 connected in series with the first switch 115. The first switch 115 and the second switch 116 form the The first connection terminal 111, the second bridge arm 114 includes a third switch 117 and a fourth switch 118 connected in series with the third switch 117, and the second switch 117 and the fourth switch 118 form the second Connect terminal 112. To avoid dead time, when the first switch 115 is turned on, the second switch 116 is turned off, and when the third switch 117 is turned on, the fourth switch 118 is turned off. In addition, the control of the first bridge arm 113 and the second bridge arm 114 is also staggered. Specifically, when the first switch 115 is turned on, the third switch 117 is turned off, and the fourth switch 118 is turned on. Accordingly, when the second switch 116 is turned on, the third switch 117 is turned on, and the fourth switch 118 is turned off. In this way, when the full-bridge rectifier unit 11 is implemented, the first connection terminal 111 or the second connection terminal 112 will output power according to the control conditions of the switches (115, 116, 117, 118). In an embodiment, the first switch 115, the second switch 116, the third switch 117, and the fourth switch 118 may be a metal oxide half field effect transistor (MOSFET), respectively. Furthermore, the first switch 115, the second switch 116, the third switch 117, and the fourth switch 118 are respectively controlled by a control module (not shown) during implementation.

In addition, the resonance unit 12 is an LLC structure, and the resonance unit 12 is connected to the first connection terminal 111 and the second connection terminal 112. The resonant unit 12 includes a first resonant inductor 121, a resonant capacitor 122, and a second resonant inductor 123, and the resonant capacitor 122 can be connected in series with the first resonant inductor 121 or the second resonant inductor 123. In addition, the dot end of the first resonant inductor 122 and the dot end of the second resonant inductor 123 are respectively connected to the resonant capacitor 122 and the full-bridge rectifier unit 11. For example, in the embodiment disclosed in FIG. 1, one end of the resonant capacitor 122 is connected in series with the second resonant inductor 123, and the other end is connected to the first connection end 111. In addition, in the embodiment disclosed in FIG. 2, one end of the resonant capacitor 122 is connected to the first resonant inductor 121 in series, and the other end is connected to the second connecting end 112. On the other hand, the first transformer 13 includes a first primary winding 131 connected in series to the first resonant inductor 121 and a first secondary winding 132 magnetically coupled with the first primary winding 131. In addition, the second transformer 14 includes a second primary winding 141 connected in series with the first primary winding 131 and connected to the second resonant inductor 123, and a second primary winding 141 that is magnetically coupled to the second primary winding 141 and is connected to the first primary winding 141. The second secondary winding 142 of the secondary winding 132 is connected in parallel, and the first secondary winding 132 and the second secondary winding 142 are respectively connected to the synchronous rectification unit 15.

In conclusion, the resonant unit 12 of the present invention adopts a symmetrical arrangement of the first resonant inductor 121 and the second resonant inductor 123, so that the magnetic path distance from the first resonant inductor 121 to the second primary winding 141 is the same as that of the second primary winding 141. The magnetic circuit distance between the resonant inductor 123 and the first primary winding 131 is the same, so that whether the power enters from the first connection end 111 or the second connection end 112, the hysteresis of the first transformer 13 and the second transformer 14 All are the same, so that there will be no phase difference between the outputs of the first transformer 13 and the second transformer 14, so that the control of the synchronous rectification unit 15 can be optimized, thereby improving the overall efficiency of the full-bridge resonant conversion circuit 10 .

Please refer to FIG. 1 again. In one embodiment, the first secondary winding 132 includes a first sub-winding 133, a second sub-winding 134 connected to the first sub-winding 133, and a second sub-winding 134 connected to the first sub-winding 133 The first output terminal 135 is connected to the second output terminal 136 of the second sub-winding 134, and the first tap output terminal 137 is connected between the first sub-winding 133 and the second sub-winding 134. In addition, the second secondary winding 142 includes a third sub winding 143, a fourth sub winding 144 connected to the third sub winding 143, a third output terminal 145 connected to the third sub winding 143, and a third output terminal 145 connected to the third sub winding 143. The fourth output end 146 of the fourth sub winding 144 is a second tap output end 147 connected between the third sub winding 143 and the fourth sub winding 144 and connected to the first tap output end 137. Further, the polarities of the first sub-winding 133 and the second sub-winding 134 are the same as the polarities of the first primary winding 131, and the polarities of the third sub-winding 143 and the fourth sub-winding 144 are the same as those of the second primary winding. 141 has the same polarity.

Continuing, and referring to FIG. 1, in one embodiment, the synchronous rectification unit 15 includes a power reference 151 (GND), and a power output terminal 152 connected to the first tap output terminal 137 and the second tap output terminal 147 , A fifth switch 153 connected to the first output terminal 135 and the power reference 151, a sixth switch 154 connected to the second output terminal 136 and the power reference 151, and a third output terminal 145 connected to the power The seventh switch 155 of the reference 151 and an eighth switch 156 connecting the fourth output terminal 146 and the power reference 151. Further, the fifth switch 153, the sixth switch 154, the seventh switch 155, and the eighth switch 156 can be a metal oxide half field effect transistor (MOSFET), wherein the fifth switch 153 is a MOSFET. The pole (D pole) is connected to the first output terminal 135, and the source (S pole) is connected to the power reference 151. In addition, the sixth switch 154 is connected to the second output terminal 136 with a drain (D pole), and connected to the power reference 151 with a source (S pole). In addition, the seventh switch 155 is connected to the third output terminal 145 with a drain (D pole), and connected to the power reference 151 with a source (S pole). In addition, the eighth switch 156 is connected to the fourth output terminal 146 with a drain (D pole), and connected to the power reference 151 with a source (S pole). Furthermore, the fifth switch 153, the sixth switch 154, the seventh switch 155, and the eighth switch 156 are respectively controlled by the control module during implementation.

In the above, please refer to FIGS. 3 and 4, in which FIG. 3 is a schematic diagram of the working waveform of one of the switches arranged on the transformer secondary of the present invention, and FIG. 4 is a schematic diagram of the working waveform of one of the switches arranged on the transformer secondary of the conventional circuit. It can be clearly understood from FIGS. 3 and 4 that the circuit of the present invention reduces the high frequency oscillation of the series loop of the first secondary winding 132 and the second secondary winding 142, and reduces the fifth switch 153 and the sixth switch 154. , The seventh switch 155 and the eighth switch 156 generate a surge at the moment of turning on, so that the withstand voltage conditions of the fifth switch 153, the sixth switch 154, the seventh switch 155, and the eighth switch 156 can be reduced. In addition, the circuit of the present invention balances the source-drain voltages (Vds) of the fifth switch 153, the sixth switch 154, the seventh switch 155, and the eighth switch 156. Furthermore, in one embodiment, the synchronous rectification unit 15 includes at least one capacitor 157 connected to the power output terminal 152 and the power reference 151, the positive electrode of the capacitor 157 is connected to the power output terminal 152, and the negative electrode is connected to the power reference 151.

The foregoing is only a preferred embodiment of the present invention, and should not be used to limit the scope of implementation of the invention, that is, all equivalent changes and modifications made in accordance with the scope of the patent application of the present invention should still be covered by the patent of the present invention.

10: Full-bridge resonant conversion circuit

11: Full bridge rectifier unit

111: first connection end

112: second connection end

113: first bridge arm

114: second bridge arm

115: first switch

116: second switch

117: The third switch

118: fourth switch

12: Resonant unit

121: The first resonant inductor

122: resonant capacitor

123: second resonant inductor

13: The first transformer

131: first primary winding

132: first secondary winding

133: first sub winding

134: second sub winding

135: First output

136: second output

137: First tap output

14: The second transformer

141: second primary winding

142: second secondary winding

143: third sub winding

144: The fourth sub winding

145: Third output

146: Fourth output

147: The second tap output

15: Synchronous rectifier unit

151: Electricity Benchmark

152: Power output

153: Fifth switch

154: Sixth Switch

155: Seventh switch

156: Eighth Switch

157: Capacitor

Claims (2)

A full-bridge resonant conversion circuit includes: a full-bridge rectifier unit, including a first connecting end, a second connecting end, a first bridge arm and a second bridge arm, the first bridge arm including a first Switch and a second switch connected in series with the first switch, the first connection terminal is formed between the first switch and the second switch, and the second bridge arm includes a third switch and a second switch connected in series with the third switch A fourth switch, the second connection terminal is formed between the third switch and the fourth switch; a resonant unit is connected to the first connection terminal and the second connection terminal, the resonant unit includes a first resonant inductor, A resonant capacitor and a second resonant inductor, the resonant capacitor is connected in series with the first resonant inductor or the second resonant inductor, and the dot end of the first resonant inductor and the dot end of the second resonant inductor are respectively connected to the resonant capacitor and The full-bridge rectifier unit; a first transformer including a first primary winding connected in series with the first resonant inductor and a first secondary winding magnetically coupled with the first primary winding, the first secondary winding including A first sub-winding, a second sub-winding connected to the first sub-winding, a first output terminal connected to the first sub-winding, a second output terminal connected to the second sub-winding, and a second sub-winding connected to the The first tap output terminal between the first sub-winding and the second sub-winding, the polarities of the first sub-winding and the second sub-winding are the same as the polarity of the first primary winding; a second transformer includes a The first primary winding is connected in series and connected to the second primary winding of the second resonant inductor, and a second secondary winding magnetically coupled to the second primary winding and parallel to the first secondary winding, the second secondary The winding includes a third sub-winding, a fourth sub-winding connected to the third sub-winding, a third output terminal connected to the third sub-winding, a fourth output terminal connected to the fourth sub-winding, and a Around the third child A second tap output terminal between the group and the fourth sub winding and connected to the first tap output terminal, the polarity of the third sub winding and the fourth sub winding is the same as the polarity of the second primary winding; and The synchronous rectification unit includes a power reference, a power output terminal connected to the first tap output terminal and the second tap output terminal, a fifth switch connected to the first output terminal and the power reference, and a power output terminal connected to the second output A sixth switch connected to the power reference, a seventh switch connected to the third output terminal and the power reference, an eighth switch connected to the fourth output terminal and the power reference, and at least one connected to the power output terminal A capacitance with the power reference; wherein the magnetic path distance from the first resonant inductor to the second primary winding is the same as the magnetic path distance from the second resonant inductor to the first primary winding. The full-bridge resonant conversion circuit according to claim 1, wherein the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch, and The eighth switches are respectively a metal oxide half field effect transistor.

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