TWI414138B - Resonant converting apparatus and synchronous rectification circuit - Google Patents

Abstract

A resonant converting apparatus including: a resonant circuit, a bridge converter, and a synchronous rectification circuit. The resonant circuit has a transformer. The bridge converter is connected with the primary side of the transformer, and operates according to a switching signal. The synchronous rectification circuit contains a pair of rectification transistors and a pair of driving circuits. The driving circuits are correspondingly connected with the rectification transistors, and respectively sense the current passed through the rectification transistors to output a sensing signal, and then the driving circuits respectively produce a driving signal according to the switching signal and the sensing signal to drive the connected rectification transistor. Thereof, the present can achieve the purpose of increasing the efficiency of the resonant converting apparatus.

Description

Resonant conversion device and synchronous rectifier circuit thereof

The invention relates to a resonance conversion device, in particular to a resonance conversion device with synchronous rectification function and a synchronous rectification circuit thereof.

The resonant converter is applied to the power supply product, and in order to improve the efficiency of the resonant converter, it is usually designed with the output synchronous rectifier circuit. Moreover, the driving effect of the synchronous rectification circuit directly affects the power conversion efficiency of the resonance conversion device, and even affects the stability at light load or no load.

At present, most of the resonant converters that are commonly seen use a diode as a synchronous rectifier circuit. As shown in the first figure, it is a circuit diagram of a conventional half-bridge LLC resonant converter. The resonant converter includes a half bridge switching circuit 91, a resonant circuit 92, a synchronous rectifying circuit 93, and an output circuit 94. The half bridge switching circuit 91 is a half bridge structure composed of a first switching transistor Q1 and a second switching transistor Q2, and is connected between a voltage source Vin and a resonant circuit 92, and the first switching transistor Q1 And the second switching transistor Q2 is operated according to a switching signal (HVG and LVG). The resonant circuit 92 further includes a transformer Tr and is a resonant circuit of an LLC architecture, wherein the secondary side coil of the transformer Tr has a first winding and a second winding; and the LLC architecture is composed of a resonant inductor Lr, a The magnetizing inductance (provided by the primary side coil of the transformer Tr) and a resonant capacitor Cr. The synchronous rectification circuit 93 includes a first rectifying diode SD1 and a second rectifying diode SD2 to be respectively connected to the first winding and the second winding, and is connected to the output circuit 94. In this way, energy can be transmitted from the primary side to the secondary side by the interaction of the primary side first switching transistor Q1 and the second switching transistor Q2.

However, since the design of the synchronous rectification circuit using the diode causes a high conduction loss (Conduction Loss), a design using a rectifying transistor with a gate driving chip has been developed to replace the rectifying diode. Please refer to the second figure for the circuit connection diagram of the rectifying transistor and the driving chip in the synchronous rectifier circuit of the prior art. In the actual synchronous rectification circuit 93', the first rectifying transistor SR1 and the second rectifying transistor SR2 are used to replace the original first rectifying diode SD1 and the second rectifying diode SD2, respectively. Then, a driver chip IC is connected to receive the driving of the driving chip IC. In the second figure, only one driving wafer IC is used to represent the architectural relationship between the driving wafer IC and the first rectifying transistor SR1 (or the second rectifying transistor SR2). The first rectifying transistor SR1 and the second rectifying transistor SR2 are metal oxide semiconductor field effect transistors (MOSFETs). The driving chip IC indirectly detects the current by detecting a drain-source voltage (Vds) of the first rectifying transistor SR1 (or the second rectifying transistor SR2) to generate or turn off the driving signal SR1_D according to the detected voltage signal (or SR2_D), while controlling the first rectifying transistor SR1 (or the second rectifying transistor SR2) to be turned on or off.

However, since the package inductance of the metal oxide semiconductor field effect transistor and the lead parasitic inductance (Lσ1 and Lσ2) of the circuit traces on the circuit board affect the result of detecting the current of the driving chip IC, the driving signal SR1_D generated by the driving chip IC is driven ( Or SR2_D) may cause an early shutdown phenomenon, so that the synchronous rectification effect of the resonance conversion device is not good, thereby affecting the conversion efficiency of the resonance conversion device.

Please refer to the third figure again for the operation waveform diagram of the conventional half-bridge LLC resonant converter. Through the third figure, the operation state of the half-bridge LLC resonant converter in conjunction with the rectifying transistor and driving the wafer can be further clearly understood. Among them, since the half-bridge LLC resonant converter has symmetry between the first half cycle and the second half cycle, the following is only exemplified in the previous half cycle.

It is assumed that the components on the half-bridge LLC resonant converter are ideal, and the analysis of the different states according to the time point is as follows: state (t0~t1): time t0 is the time at which a resonance cycle is restarted. In this state, the first switching transistor Q1 and the second switching transistor Q2 are both turned off, and the resonant current (i _Lr ) first flows through the junction capacitance of the first switching transistor Q1 (not shown) until the first The drain-source voltage (Vds) of the switching transistor Q1 is zero, and the resonant current (i _Lr ) flows through the body diode of the first switching transistor Q1 (not shown). Among them, the resonant current (i _Lr ) is gradually increased in the form of an approximately sinusoidal wave, and the current (i _Lm ) on the magnetizing inductance is linearly increased. On the other hand, since the voltage signal on the secondary side of the transformer Tr starts to reverse, the second rectifying transistor SR2 starts to conduct, and therefore, in this state, the voltage of the exciting inductor is clamped by the output voltage Vout, so only the resonant inductor Lr Resonance with the resonant capacitor Cr, and the resonant current (i _Lr ) will be greater than the current (i _Lm ) on the magnetizing inductance, and become the current (i _SR2 ) flowing through the second rectifying transistor SR2. Finally, when the time is t1, the switching signal HVG controls the first switching transistor Q1 to be turned on under zero voltage conditions.

State (t1~t2): In this state, except that the first switching transistor Q1 is already on, and the resonant current (i _Lr ) is directly flowing through the channel of the first switching transistor Q1 and continues to increase, the rest The operation of the component is roughly the same as the state (t0~t1). However, as previously mentioned, the package inductance of the metal oxide semiconductor field effect transistor and the lead parasitic inductance (Lσ1 and Lσ2) of the circuit traces on the circuit board affect the result of detecting the current of the driving chip IC, so before the arrival time t2, The driving chip IC may turn off the driving signal SR2_D by a certain period of time T due to the influence of the detection current, and form a rectification by the body diode of the second rectifying transistor SR2. As a result, it will result in higher conduction loss and reduce the synchronous rectification effect. When the arrival time t2 is reached, the resonant current (i _Lr ) will be equal to the current (i _Lm ) on the magnetizing inductance, so the transformer Tr has no energy transfer, and the current flowing through the second rectifying transistor SR2 (i _SR2 ) will Will drop to zero.

State (t2~t3): The first switching transistor Q1 in this state is continuously turned on. Since the resonant current (i _Lr ) is greater than zero and equal to the current (i _Lm ) on the magnetizing inductance, the transformer Tr is regarded as an open circuit without energy transfer, and the voltage of the exciting inductor will not be clamped by the output voltage Vout, so the excitation The inductor will participate in the resonance of the resonant inductor Lr and the resonant capacitor Cr. At the end of this state, the first switching transistor Q1 is controlled to be turned off under zero voltage conditions.

As can be seen from the above description, in the current resonant converter device, there is a design for synchronous rectification using a rectifying transistor, but a design method in which the driving chip indirectly detects the current by detecting the drain-source voltage of the rectifying transistor causes Synchronous rectification drives do not achieve better results and there is room for further improvement in efficiency.

In view of the above, the technical problem to be solved by the present invention is that, in terms of driving control, in addition to directly detecting the current flowing through the rectifying transistor, the switching signal on the primary side of the transformer is further introduced to perform a judgment operation, and further, according to the operation. As a result, the rectifying transistor is driven.

In order to solve the above problems, according to an aspect of the present invention, a resonance conversion device includes: a resonance circuit, a bridge conversion circuit, and a synchronous rectification circuit. The resonant circuit includes a transformer, and the bridge conversion circuit is connected to the primary side of the transformer, and is opened and closed according to a switching signal. The synchronous rectification circuit further includes: a second rectifying transistor and a second driving circuit. Wherein, the two rectifying transistors are respectively connected to a first winding and a second winding of the secondary side coil of the transformer, and the two driving circuits are corresponding to the channels connecting the two rectifying transistors, and respectively generate a driving signal To drive the connected rectifier transistor. The two driving circuits respectively detect a current flowing through the connected rectifying transistor to generate a detection signal, and generate a driving signal according to a switching signal and a detection signal of the bridge conversion circuit on the primary side of the transformer.

In order to solve the above problems, according to another aspect proposed by the present invention, a synchronous rectification circuit is provided which is applied to a resonance conversion device and is connected to a secondary side coil of a transformer of the resonance conversion device, and the primary side of the transformer is A bridge conversion circuit is connected, and the synchronous rectifier circuit comprises: a two-rectifying transistor and a two-drive circuit. The two rectifying transistors are respectively connected to a first winding and a second winding of the secondary side coil of the transformer, and the two driving circuits are corresponding to the channels connecting the two rectifying transistors, and respectively generate a driving signal. Drive the connected rectifying transistor. The two driving circuits respectively detect a current flowing through the connected rectifying transistor to generate a detection signal, and generate the driving signal according to a switching signal and a detection signal of the bridge conversion circuit.

Thereby, the achievable effect of the present invention is that the stability at light load or no load can be effectively improved, the effect of synchronous rectification driving can be improved, and the efficiency of the resonance conversion device can be improved.

The above summary, the following detailed description and the annexed drawings are intended to further illustrate the manner, the Other objects and advantages of the present invention will be described in the following description and drawings.

The invention utilizes a rectifying transistor as a synchronous rectification in a resonant converter device, and a portion of a gate terminal driving control of a rectifying transistor is a signal for directly detecting a current flowing through the rectifying transistor, and a transformer The primary side switching signal is operated to generate a drive signal to drive the rectifying transistor. Among them, in the design of the rectifying transistor, for example, an N-channel metal oxide semiconductor field effect transistor (N Channel MOSFET) or other suitable transistor can be used.

Please refer to the fourth figure, which is a block diagram of an embodiment of a resonant converter device of the present invention. The embodiment provides a resonance conversion device including: a resonance circuit 11, a bridge conversion circuit 12, a synchronous rectifier circuit 13, and an output circuit 14. For the circuit aspect of the embodiment of the resonant converter, please refer to the fifth and sixth figures together, which is a circuit diagram of an embodiment of the half-bridge LLC resonant converter and its driving circuit of the present invention.

The resonant circuit 11 is comprised of a transformer Tr, and as shown in the fifth figure is a resonant circuit 11 of an LLC architecture. The LLC architecture is composed of a resonant inductor Lr, a magnetizing inductance (provided by the primary side coil of the transformer Tr), and a resonant capacitor Cr. The secondary side coil of the transformer Tr has a first winding and a second winding. Of course, the resonant circuit 11 can also be designed in the actual design by using an LC architecture.

The bridge conversion circuit 12 is connected to the primary side of the transformer Tr for connecting a voltage source Vin and performing an opening and closing operation according to a switching signal (HVG, LVG). As shown in the fifth figure, the bridge conversion circuit 12 is designed, for example, by a symmetric half bridge conversion circuit, and includes a first switching transistor Q1 and a second switching transistor Q2. Wherein, the first switching transistor Q1 is a control for receiving a switching signal (HVG), and the second switching transistor Q2 is a control for receiving a switching signal (LVG), and the switching signals (HVG, LVG) are complementary to a fixed duty ratio. signal. Those skilled in the art should understand that the bridge conversion circuit 12 is more specifically designed as a full-bridge conversion circuit, and is not limited by this embodiment.

The synchronous rectification circuit 13 further includes a first rectifying transistor SR1, a second rectifying transistor SR2, a first driving circuit DR1, and a second driving circuit DR2. The first rectifying transistor SR1 and the second rectifying transistor SR2 are respectively connected to the first winding and the second winding of the secondary side coil of the transformer Tr, and are connected to the output circuit 14 to output an output voltage Vout to Load 15. The first driving circuit DR1 and the second driving circuit DR2 are respectively connected to the channels connected to the first rectifying transistor SR1 and the second rectifying transistor SR2 to respectively generate a driving signal (SR1_D and SR2_D) to drive the connected A rectifying transistor SR1 and a second rectifying transistor SR2. It is worth mentioning that when the first driving circuit DR1 and the second driving circuit DR2 are in operation, the current flowing through the first rectifying transistor SR1 and the second rectifying transistor SR2 connected to each other is detected to generate a detection signal. (SR1_S and SR2_S), and further generate drive signals (SR1_D and SR2_D) based on the switching signals (LVG, HVG) of the primary side of the transformer Tr and the detection signals (SR1_S and SR2_S).

From the architecture of the fourth and fifth figures, those skilled in the art should be able to understand the operation principle of the resonant converter, that is, when the first switching transistor Q1 on the primary side of the transformer Tr receives the switching signal (HVG). In the case of conduction, the operation is performed by the second rectifying transistor SR2 and the second driving circuit DR2 on the secondary side; otherwise, the second rectifying transistor SR1 and the first driving circuit DR1 on the secondary side are used. Operation, thus achieving an interactive relationship.

Further, since the resonance switching device has symmetry between the first half cycle and the second half cycle, the following description is exemplified only for the previous half cycle. And since the resonant converter device generates the switching signal (HVG) in the first half cycle, it is represented by the relevant symbol of the second driving circuit DR2, and the driving circuit shown in the sixth figure can be assumed to be the second driving circuit DR2. The second rectifying transistor SR2 is driven to generate a driving signal (SR2_D). Incidentally, the symbols in parentheses in the sixth figure represent the relevant symbols of the first driving circuit DR1 when the second half cycle receives the switching signal (LVG).

It can be seen from the architecture of the driving circuit of the sixth figure that the second driving circuit DR2 includes a current detecting circuit 131, an isolation transformer 132 and an arithmetic processing unit 133. The current detecting circuit 131 further includes: a current transformer CT, a clamping circuit (including a first diode D1 and a DC power supply DC) and a reset circuit (including a reset resistor R1 and a second diode) Body D2).

The primary side coil of the current transformer CT is a channel connected in series to the second rectifying transistor SR2 to detect a current flowing through the second rectifying transistor SR2. The positive terminal of the first diode D1 in the clamp circuit is the positive terminal of the secondary side coil connected to the current transformer CT, and the negative terminal of the first diode D1 is connected to the positive terminal of the DC power supply DC, and the DC power supply The negative terminal of the DC is the negative terminal of the secondary side coil to which the current transformer CT is connected. The positive terminal of the second diode D2 in the reset circuit is connected to the negative terminal of the secondary side coil of the current transformer CT, and the negative terminal of the second diode D2 is connected to one end of the negative resistance R1, and the reset resistor R1 The other end is the positive terminal of the secondary side coil to which the current transformer CT is connected.

In this way, when there is current on the primary side of the current transformer CT, the secondary side of the current transformer CT transmits energy to the DC power source DC through the clamp circuit. When there is no current on the primary side of the current transformer CT, the secondary side of the current transformer CT is reset by the reset circuit. Therefore, under this operating principle, the current detecting circuit 131 can provide the detection signal of the actual current through the contact of the second diode D2 and the reset resistor R1.

The primary side of the isolation transformer 132 is for detecting a switching signal (HVG) belonging to the primary side of the transformer Tr, and the secondary side of the isolation transformer 132 is capable of generating a synchronous switching signal (HVG_S), thereby allowing the secondary side of the transformer Tr to be The second drive circuit DR2 is able to receive the synchronous switching signal (HVG_S) without a delay.

The operation processing unit 133 further includes: a monostable flip-flop 1331, a gate 1332, a gate 1333, and a driver 1334. Wherein, the input end of the monostable flip-flop 1331 is connected to the secondary side of the isolation transformer 132 to receive the synchronous switch signal (HVG_S) and generate a pulse signal; or an input terminal of the gate 1332 is connected to the monostable trigger The output of 1331 receives the pulse signal, and the other input of the gate 1332 is connected to the current detecting circuit 131 to receive the detection signal (SR2_S); and an input of the gate 1333 is connected to the secondary side of the isolation transformer 132. To receive the synchronous switch signal (HVG_S), and the other input terminal of the gate 1333 is an output terminal of the connection or gate 1332; finally, the driver 1334 is an output terminal of the connection and gate 1333, and is output according to the gate 1333. The signal is generated to generate a drive signal (SR2_D).

In the above, the design of the single-state flip-flop 1331 and the current detecting circuit 131 through the gate 1332 can be compared with the waveform of the first embodiment of the driving signal of the present invention. schematic diagram. When light load or no load occurs, the detection signal (SR2_S) outputted by the current transformer CT in the current detecting circuit 131 is easily affected by the reverse current of the detection current, so that the driving rising edge of the detection signal (SR2_S) is not fixed. It is easy to cause shocks. Thus, with the design of the embodiment, when the one-shot 1331 receives the rising edge of the synchronous switching signal (HVG_S), the one-shot 1331 then generates a pulse signal. In this way, the pulse signal of the one-shot 1331 can be OR-ORed with the detection signal (HVG_S) of the current detecting circuit 131, thereby ensuring that the second driving circuit DR2 can generate the driving signal in FIG. The waveform makes the entire resonant converter more stable.

In addition, the monostable flip-flop 1331 is designed to adjust the width of the output pulse signal through the resistor (Rd) and the capacitor (Cd), that is, the minimum on-time as shown in FIG. (tw). The preferred adjustment is not to exceed the actual maximum switching frequency (fs) to be stable at light or no load, and this embodiment is not limited.

In addition, in the embodiment, the design of the output of the gate 1332 and the synchronous switch signal (HVG_S) is transmitted through the gate 1333, and the waveform of the second embodiment of the driving signal of the present invention can be compared with the seventh diagram. Generate a schematic. In the case where the switching frequency (fs) is greater than the resonance frequency (fr), it is often necessary to reset the current transformer CT in the current detecting circuit 131, and the detection signal as shown in FIG. Only then will it affect efficiency and be unsafe. In order to avoid the delay of the output of the gate 1332 due to the reset delay of the current transformer CT, so as to affect the turn-off time of the drive signal (SR2_D), the output of the gate 1332 can be turned on by the design of the embodiment. The AND logic operation is performed with the synchronous switching signal (HVG_S) to ensure that the second driving circuit DR2 generates a waveform of the driving signal as shown in FIG. 7B and turns off in time when the synchronous switching signal (HVG_S) falls.

The driver 1334 is an output signal of the receiving and gate 1333, and is used to generate a driving signal (SR2_D) for driving the second rectifying transistor SR2. The driver 1334 can be further processed after being processed according to the requirements of the control, for example, the output signal of the gate 1333 is reverse processed and then output. In this regard, there is no limitation in this embodiment.

Finally, those skilled in the art should be able to understand that the arithmetic processing unit 133 in this embodiment can be designed in accordance with the circuit architecture described above, and other circuit modes can be obtained under the premise that the above effects can be achieved. Implementation is even possible by means of a single-chip controller.

In summary, the present invention operates in accordance with the design architecture of the above-described resonant converter device, and the associated waveform generated can refer to the eighth diagram, which is an operational waveform diagram of an embodiment of the resonant converter device of the present invention. The waveforms of the drive signals (SR2_D and SR1_D) shown therein can be effectively synchronously rectified to ensure reliable turn-on and turn-off. Thereby, the stability at the time of light load or no load can be improved, the effect of the synchronous rectification drive can be improved, and the efficiency of the resonance conversion device can be improved.

However, the above description is only for the purpose of illustration and illustration of the embodiments of the present invention, and is not intended to limit the scope of the invention. Variations or modifications that may be readily conceived within the scope of the invention may be covered by the scope of the invention as defined in the following.

[Practical Technology]

91. . . Half bridge conversion circuit

92. . . Resonant circuit

93,93’. . . Synchronous rectifier circuit

94. . . Output circuit

Cr. . . Resonant capacitor

HVG, LVG. . . Switching signal

IC. . . Driver chip

Lr. . . Resonant inductor

Q1. . . First switching transistor

Q2. . . Second switching transistor

SD1. . . First rectifier diode

SD2. . . Second rectifying diode

SR1. . . First rectifying transistor

SR2. . . Second rectifier transistor

SR1_D, SR2_D. . . Drive signal

Tr. . . transformer

Vin. . . power source

Vout. . . The output voltage

[this invention]

11. . . Resonant circuit

12. . . Bridge conversion circuit

13. . . Synchronous rectifier circuit

131. . . Current detection circuit

132. . . Isolation transformer

133. . . Operation processing unit

1331. . . Monoflop

1332. . . Gate

1333. . . Gate

1334. . . driver

14. . . Output circuit

15. . . load

CT. . . Current Transformer

Cr. . . Resonant capacitor

D1. . . First diode

D2. . . Second diode

DC. . . DC power supply

DR1. . . First drive circuit

DR2. . . Second drive circuit

HVG, LVG. . . Switching signal

HVG_S, LVG_S. . . Synchronous switch signal

Lr. . . Resonant inductor

Q1. . . First switching transistor

Q2. . . Second switching transistor

R1. . . Reset resistor

SR1. . . First rectifying transistor

SR2. . . Second rectifier transistor

SR1_D, SR2_D. . . Drive signal

SR1_S, SR2_S. . . Detection signal

Tr. . . transformer

Vin. . . power source

Vout. . . The output voltage

The first figure is a circuit diagram of a conventional half-bridge LLC resonant converter device;

The second figure is a schematic diagram of the circuit connection of the rectifying transistor and the driving chip in the synchronous rectification circuit of the prior art;

The third figure is an operational waveform diagram of a conventional half-bridge LLC resonant converter device;

Figure 4 is a block diagram of an embodiment of a resonant converter device of the present invention;

The fifth figure is a circuit diagram of an embodiment of a half bridge LLC resonant converter;

Figure 6 is a circuit diagram showing an embodiment of a driving circuit of the present invention;

Figure 7A is a schematic diagram showing the waveform generation of the first embodiment of the driving signal of the present invention;

Figure 7B is a schematic diagram showing waveform generation of the second embodiment of the driving signal of the present invention;

The eighth diagram is an operational waveform diagram of an embodiment of the resonant converter of the present invention.

11. . . Resonant circuit

12. . . Bridge conversion circuit

13. . . Synchronous rectifier circuit

14. . . Output circuit

15. . . load

DR1. . . First drive circuit

DR2. . . Second drive circuit

HVG, LVG. . . Switching signal

SR1. . . First rectifying transistor

SR2. . . Second rectifier transistor

SR1_D, SR2_D. . . Drive signal

Vin. . . power source

Vout. . . The output voltage

Claims (11)

A resonant converter device comprising: a resonant circuit comprising a transformer; a bridge switching circuit connected to the primary side of the transformer and operating in accordance with a switching signal; and a synchronous rectifying circuit comprising: a rectifying transistor is respectively connected to a first winding and a second winding of the secondary side coil of the transformer; and a second driving circuit corresponding to the channel connecting the two rectifying transistors, and respectively generating a driving signal to drive the The connected rectifying transistor; wherein the two driving circuits respectively detect a current flowing through the connected rectifying transistor to generate a detecting signal, and generate the driving signal according to the switching signal and the detecting signal. The resonant converter device of claim 1, wherein each of the driving circuits comprises a current detecting circuit, and the current detecting circuit further comprises: a current transformer, the primary side coil system of the current transformer is connected a channel of the rectifying transistor to detect a current flowing through the rectifying transistor; a clamping circuit comprising a first diode and a DC power source, wherein the positive terminal of the first diode is connected to the current mutual inductance The positive end of the secondary side coil of the device, and the negative end of the first diode is connected to the positive end of the DC power source, and the negative end of the DC power source is connected to the negative end of the secondary side coil of the current transformer; And a reset circuit comprising a reset resistor and a second diode, wherein the positive end of the second diode is connected to the negative terminal of the secondary side coil of the current transformer, and the second diode is negative The end is connected to one end of the reset resistor, and the other end of the reset resistor is connected to the positive terminal of the secondary side coil of the current transformer; wherein the current detecting circuit is connected to the reset resistor by the second diode Contact To provide the detection signal. The resonant converter device of claim 2, wherein each of the driving circuits further comprises an isolation transformer that detects the switching signal to generate a synchronous switching signal. The resonant converter device of claim 3, wherein each of the driving circuits comprises an arithmetic processing unit, the arithmetic processing unit further comprising: a monostable trigger connected to the isolation transformer for receiving the Synchronizing the switching signal and generating a pulse signal; an OR gate, an input of the OR gate is connected to the one-shot trigger to receive the pulse signal, and another input terminal of the OR gate is connected to the current detection a circuit for receiving the detection signal; a gate, an input of the gate is connected to the isolation transformer to receive the synchronous switch signal, and another input terminal of the gate is connected to an output of the gate And a driver connected to an output of the gate and generating the driving signal according to the signal of the output of the gate. The resonant converter device of claim 1, further comprising: an output circuit connecting the two rectifying transistors and outputting an output voltage to a load. The resonant converter device of claim 1, wherein the resonant circuit is one of a resonant circuit of an LLC architecture and a resonant circuit of an LC architecture. The resonant converter device of claim 1, wherein the bridge converter circuit is one of a symmetric half bridge conversion circuit and a full bridge conversion circuit. A synchronous rectification circuit is applied to a resonance conversion device and is connected to a secondary side coil of a transformer of the resonance conversion device, and a primary side of the transformer is connected to a bridge conversion circuit, and the synchronous rectification circuit comprises: two rectification a transistor, which is respectively connected to a first winding and a second winding of the secondary side coil of the transformer; and a second driving circuit corresponding to the channel connecting the two rectifying transistors, and respectively generating a driving signal to drive the connected a rectifying transistor; wherein the two driving circuits respectively detect a current flowing through the connected rectifying transistor to generate a detecting signal, and generate the driving signal according to a switching signal of the bridge converting circuit and the detecting signal . The synchronous rectification circuit of claim 8, wherein each of the driving circuits comprises a current detecting circuit, and the current detecting circuit further comprises: a current transformer, the primary side coil system of the current transformer is connected a channel of the rectifying transistor to detect a current flowing through the rectifying transistor; a clamping circuit comprising a first diode and a DC power source, wherein the positive terminal of the first diode is connected to the current mutual inductance The positive end of the secondary side coil of the device, and the negative end of the first diode is connected to the positive end of the DC power source, and the negative end of the DC power source is connected to the negative end of the secondary side coil of the current transformer; And a reset circuit comprising a reset resistor and a second diode, wherein the positive end of the second diode is connected to the negative terminal of the secondary side coil of the current transformer, and the second diode is negative The end is connected to one end of the reset resistor, and the other end of the reset resistor is connected to the positive terminal of the secondary side coil of the current transformer; wherein the current detecting circuit is connected to the reset resistor by the second diode Contact To provide the detection signal. The synchronous rectification circuit of claim 9, wherein each of the driving circuits further comprises an isolation transformer, wherein the isolation transformer detects the switching signal to generate a synchronous switching signal. The synchronous rectification circuit of claim 10, wherein each of the driving circuits comprises an operation processing unit, the operation processing unit further comprising: a monostable trigger connected to the isolation transformer for receiving the Synchronizing the switching signal and generating a pulse signal; an OR gate, an input of the OR gate is connected to the one-shot trigger to receive the pulse signal, and another input terminal of the OR gate is connected to the current detection a circuit for receiving the detection signal; a gate, an input of the gate is connected to the isolation transformer to receive the synchronous switch signal, and another input terminal of the gate is connected to an output of the gate And a driver connected to an output of the gate and generating the driving signal according to the signal of the output of the gate.