Bridge flyback topology circuit and switching power supply

Abstract

The present invention provides a power module, a bridge flyback topology circuit and a switching power supply, including: an upper tube and a lower tube are gallium nitride power tubes; the drain of the upper tube is connected to a DC input voltage, the source is connected to the cathode of a first diode, and the gate receives a first drive signal; the first diode, the anode is grounded; the second diode, the cathode is connected to the DC input voltage, the anode is connected to the drain of the lower tube; the source of the lower tube is grounded, and the gate is connected to the second drive signal; an output transformer, the primary winding is connected between the source of the upper tube and the drain of the lower tube, and the secondary winding is connected to the output circuit. The present invention uses the reverse conduction characteristics of cascaded gallium nitride and two high-efficiency diodes to build a bridge circuit, effectively absorbs the energy generated by leakage inductance, has a small size, low cost, and low power consumption; and effectively solves the problems of common-mode interference and standby power consumption.

Description

Technical Field

[0001] The present invention relates to the field of power supplies, and in particular to a bridge flyback topology circuit and a switching power supply. Background Art

[0002] Switching power supplies are divided into two types: isolated and non-isolated. Among them, isolated switching power supplies can be divided into forward and flyback types according to different structural forms. The flyback power supply eliminates the large volume of inductor and is widely used in small and medium power supplies due to its simple structure.

[0003] Due to the leakage inductance of the transformer, the existing flyback power supply cannot achieve a full voltage range of 90Vac-264Vac input power supply when the output power is large (for example, greater than 150W). The peak voltage of the drain of the power switch tube is high, and the energy absorption of the RCD absorption network is limited, which can easily break down the power switch tube; and the common-mode interference of the power switch tube cannot be suppressed and can easily be transmitted to the driving circuit of the power switch tube, affecting the circuit performance; in addition, two clamping diodes are required, which is costly.

[0004] Therefore, how to solve the high-power output problem of the flyback circuit while achieving miniaturization, improving power density and efficiency, reducing costs, and suppressing common-mode interference has become an urgent problem to be solved by technical personnel in this field.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0006] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a bridge flyback topology circuit and a switching power supply, which are used to solve the problems in the prior art that the flyback power supply cannot achieve high power output, the drain peak voltage is high, the power switch tube is easy to break down, the common mode interference cannot be suppressed, the size is large, the cost is high, etc.

[0007] To achieve the above-mentioned object and other related objects, the present invention provides a cascaded gallium nitride bridge power module, wherein the cascaded gallium nitride bridge power module at least comprises:

[0008] An upper tube, a lower tube, a first diode, a second diode and an output transformer, wherein the upper tube and the lower tube are gallium nitride power tubes;

[0009] The drain of the upper tube is connected to the DC input voltage, the source is connected to the cathode of the first diode, and the gate receives the first driving signal; the anode of the first diode is grounded;

[0010] The cathode of the second diode is connected to the DC input voltage, and the anode is connected to the drain of the lower tube; the source of the lower tube is grounded, and the gate is connected to the second driving signal;

[0011] The primary winding of the output transformer is connected between the source of the upper tube and the drain of the lower tube, and the secondary winding is connected to the output circuit.

[0012] Optionally, the drains of the upper tube and the lower tube are respectively connected in series with magnetic beads.

[0013] Optionally, the output transformer further includes a primary auxiliary winding, wherein the primary auxiliary winding is connected to a detection circuit, and the detection circuit detects a voltage on the primary auxiliary winding.

[0014] More optionally, the cascaded gallium nitride bridge power module further includes a first resistor, which is connected in series between the source of the lower tube and the ground.

[0015] In order to achieve the above-mentioned object and other related objects, the present invention further provides a bridge flyback topology circuit, wherein the bridge flyback topology circuit at least comprises:

[0016] A driving module, an isolation module, an upper tube gate control module, a lower tube gate control module and the above-mentioned cascaded gallium nitride bridge power module;

[0017] The driving module receives a driving signal and performs power amplification on the driving signal;

[0018] The isolation module is connected to the output end of the driving module to perform high and low voltage isolation on the output signal of the driving module;

[0019] The upper tube gate control module is connected to the output end of the isolation module, and drives the upper tube to be turned on or off based on the output signal of the isolation module;

[0020] The lower tube gate control module is connected to the output end of the driving module, and drives the lower tube to be turned on or off based on the output signal of the driving module.

[0021] Optionally, the driving module is a totem pole structure.

[0022] Optionally, the isolation module includes a third diode, a first capacitor, a driving transformer and a second resistor;

[0023] The cathode of the third diode is connected to the output end of the driving module, and the anode is connected to the first end of the primary winding of the driving transformer;

[0024] The first capacitor is connected in parallel to two ends of the third diode;

[0025] The second end of the primary winding of the driving transformer is grounded via the second resistor, and the secondary winding is connected to the upper tube gate control module.

[0026] Optionally, the upper tube gate control module and the lower tube gate control module both include an opening unit and a closing unit;

[0027] One end of the opening unit receives the corresponding driving signal, and the other end is connected to the gate of the corresponding power tube, so as to control the corresponding power tube to be turned on;

[0028] The shut-off unit is connected between the gate and source of the corresponding power tube, and controls the corresponding power tube to shut down based on the corresponding driving signal.

[0029] More optionally, the turn-on unit includes a third resistor, a second capacitor and a fourth diode; one end of the third resistor is connected to the corresponding drive signal, and the other end is connected to the anode of the fourth diode; the cathode of the fourth diode is connected to the gate of the corresponding power tube; the second capacitor is connected in parallel to both ends of the third resistor.

[0030] More optionally, the shutdown unit includes a fourth resistor, a pull-down tube and a fifth diode; one end of the fourth resistor is connected to the gate of the corresponding power tube, and the other end is connected to the anode of the fifth diode via the pull-down tube; the cathode of the fifth diode is connected to the source of the corresponding power tube.

[0031] More optionally, the upper tube gate control module and the lower tube gate control module further include a common mode interference suppression unit, and the common mode interference suppression unit is connected between the gate and source of the corresponding power tube.

[0032] More optionally, the common-mode interference suppression unit includes a first transient voltage suppression diode and a second transient voltage suppression diode, the anodes of the first transient voltage suppression diode and the second transient voltage suppression diode are connected together, and the cathodes are respectively connected to the gate and source of the corresponding power tube.

[0033] More optionally, the upper tube gate control module and the lower tube gate control module also include a shutdown negative voltage generating unit, one end of the shutdown negative voltage generating unit is connected to the output end of the opening unit and the input end of the shutdown unit, and the other end is connected to the gate of the corresponding power tube.

[0034] More optionally, the shutoff negative pressure generating unit is a magnetic bead.

[0035] To achieve the above-mentioned object and other related objects, the present invention further provides a switching power supply, which at least includes: a voltage input circuit, a drive signal generating circuit and the above-mentioned bridge flyback topology circuit;

[0036] The voltage input circuit converts the AC input voltage into a DC input voltage;

[0037] The driving signal generating circuit is used to generate the driving signal;

[0038] The bridge flyback topology circuit is connected to the voltage input circuit and the drive signal generating circuit, and converts the DC input voltage into a preset output voltage based on the control of the drive signal.

[0039] As described above, the bridge flyback topology circuit and the switching power supply of the present invention have the following beneficial effects:

[0040] 1. The power module, bridge flyback topology circuit and switching power supply of the present invention utilize the reverse conduction characteristics of cascaded gallium nitride and two high-efficiency diodes to build a bridge circuit to effectively absorb the energy generated by leakage inductance.

[0041] 2. The power module, bridge flyback topology circuit and switching power supply of the present invention do not require an RCD absorption network, and recover the energy of the leakage inductance to the DC bus, and are small in size, low in cost, and low in power consumption.

[0042] 3. The power module, bridge flyback topology circuit and switching power supply of the present invention utilize the high frequency characteristics of gallium nitride to increase the switching frequency, reduce the primary inductance, and weaken the leakage inductance of the transformer.

[0043] 4. The power module, bridge flyback topology circuit and switching power supply of the present invention effectively solve the problems of common-mode interference and standby power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic structural diagram of the cascaded gallium nitride bridge power module of the present invention.

[0045] Figure 2 Shown is a schematic diagram of the forward conduction principle of cascaded GaN.

[0046] Figure 3 It shows a schematic diagram of the reverse conduction principle of cascaded GaN when Vgs<Vth.

[0047] Figure 4 Shown is a schematic diagram of the reverse conduction principle of cascaded GaN when Vgs>Vth.

[0048] Figure 5 It is a schematic diagram showing the structure of the bridge flyback topology circuit of the present invention.

[0049] Figure 6 It is a schematic diagram showing the driving voltage waveform of the cascade-type gallium nitride bridge power module of the present invention.

[0050] Figure 7Shown is a schematic diagram of the Vds waveform of the upper tube of the present invention.

[0051] Figure 8 Shown is a schematic diagram of the Vds waveform of the lower tube of the present invention.

[0052] Fig. 9 Shown is a schematic diagram of the excitation current waveform of the output transformer of the present invention.

[0053] Fig.10 Shown is a schematic structural diagram of the switching power supply of the present invention.

[0054] Component number description

[0055] 1 Bridge flyback topology circuit

[0056] 11 Cascaded GaN Bridge Power Module

[0057] 111 RC Circuit

[0058] 12 Driver Module

[0059] 13 Isolation module

[0060] 14a Upper tube gate control module

[0061] 14b Lower tube gate control module

[0062] 141 Opening Unit

[0063] 142 Shutdown unit

[0064] 143 Common mode interference suppression unit

[0065] 2 Voltage input circuit

[0066] 21 Inductor

[0067] 22 Rectifier

[0068] 3. Driving signal generation circuit

[0069] 31 Driver chip

[0070] 4 Detection circuit

[0071] 5 Output Circuit DETAILED DESCRIPTION

[0072] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0073] See also Figures 1 to 10 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0074] like Figure 1 As shown, the present invention provides a cascaded gallium nitride bridge power module 11, and the cascaded gallium nitride bridge power module 11 includes:

[0075] An upper tube Q1, a lower tube Q2, a first diode D1, a second diode D2 and an output transformer T1; the upper tube Q1 and the lower tube Q2 are gallium nitride power tubes.

[0076] like Figure 1 As shown, the drain of the upper tube Q1 is connected to the DC input voltage HV, the source is connected to the cathode of the first diode D1, and the gate receives the first drive signal Drv1; the anode of the first diode D1 is grounded. The cathode of the second diode D2 is connected to the DC input voltage HV, and the anode is connected to the drain of the lower tube Q2; the source of the lower tube Q2 is grounded, and the gate is connected to the second drive signal Drv2. The primary winding of the output transformer T1 is connected between the source of the upper tube Q1 and the drain of the lower tube Q2, and the secondary winding is connected to the output circuit ( Figure 1 not shown).

[0077] Specifically, in this embodiment, the upper tube Q1 and the lower tube Q2 are both NMOS tubes. The upper tube Q1, the lower tube Q2, the first diode D1 and the second diode D2 form a bridge structure. As another implementation of the present invention, the drains of the upper tube Q1 and the lower tube Q2 are also connected in series with magnetic beads, such as Figure 1 As shown, one end of the first magnetic bead L1 is connected to the DC input voltage HV, and the other end is connected to the drain of the upper tube Q1; one end of the second magnetic bead L2 is connected to the connection node between the second diode D2 and the output transformer T1, and the other end is connected to the drain of the lower tube Q2; the magnetic bead can absorb electromagnetic interference and dissipate it in the form of heat. Further, the output transformer T1 includes a primary winding and a secondary winding, wherein the 5th pin of the primary winding is connected to the source of the upper tube Q1, and the 4th pin is connected to the anode of the second diode D2.

[0078] Specifically, in this example, the primary winding of the output transformer T1 includes three pins (pin 4, pin 5 and pin 6 respectively). In actual use, the number of primary winding pins can be configured as needed; similarly, in this example, the secondary winding of the output transformer T1 includes three pins (pin 1, pin 2 and pin 3 respectively). In actual use, the number of secondary winding pins can be configured according to the specific structure of the output circuit; it is not limited to this embodiment.

[0079] Specifically, as another implementation of the present invention, the output transformer T1 further includes a primary auxiliary winding, and the primary auxiliary winding is connected to the detection circuit ( Figure 1 The detection circuit detects the voltage on the primary auxiliary winding and feeds it back to the front-end control circuit (including but not limited to the control circuit that generates the drive signal).

[0080] Specifically, as another implementation of the present invention, the cascaded gallium nitride bridge power module 11 further includes a first resistor R1, which is connected in series between the source of the lower tube Q2 and the ground, and is used to sample the current flowing through the lower tube Q2. In actual use, other devices capable of current sampling may also be used, and are not limited to this embodiment.

[0081] Specifically, as another implementation of the present invention, two ends of the upper tube Q1 and the lower tube Q2 are respectively connected in parallel with an RC circuit 111, in which a resistor and a capacitor are connected in series, which will not be described in detail here.

[0082] like Figure 2 to Figure 4 The figure shows the conduction characteristics of cascaded GaN. Taking the cascade structure of a low-voltage metal oxide semiconductor field effect transistor MOS and a depletion-mode GaN HEMT as an example, when forward-conducting, the current passes through the depletion-mode GaN HEMT and the low-voltage metal oxide semiconductor field effect transistor MOS in sequence, as shown in FIG. Figure 2 When conducting in reverse, if Vgs < Vth, the current passes through the body diode of the low-voltage metal oxide semiconductor field effect transistor MOS and the depletion-mode GaN HEMT in turn, as shown in Figure 1. Figure 3 As shown; if Vgs>Vth, the current passes through the low-voltage metal oxide semiconductor field effect transistor MOS and the depletion mode GaN HEMT in turn, as shown Figure 4 As shown. Figure 1As shown, in the present invention, two cascaded gallium nitride power tubes in the cascaded gallium nitride bridge power module 11 are connected in series with the primary winding of the output transformer T1, and the two gallium nitride power tubes are turned on or off at the same time. When the two gallium nitride power tubes are turned on at the same time, the primary winding of the output transformer T1 stores energy. When the two gallium nitride power tubes are turned off, the secondary winding transmits excitation energy to the output end. Due to the reverse conduction characteristics of the cascaded gallium nitride power tube, the leakage inductance energy is recovered to the input end (HV end) through the bridge circuit composed of the upper tube Q1, the lower tube Q2, the first diode D1 and the second diode D2. It should be noted that in this example, the lower tube Q2 is turned on before the upper tube Q1, and is turned off before the upper tube Q1.

[0083] like Figure 5 As shown, the present invention also provides a bridge flyback topology circuit 1, and the bridge flyback topology circuit 1 includes:

[0084] The cascaded GaN bridge power module 11, the driving module 12, the isolation module 13, the upper tube gate control module 14a and the lower tube gate control module 14b.

[0085] like Figure 5 As shown, the driving module 12 receives the driving signal GT and performs power amplification on the driving signal GT.

[0086] Specifically, in this embodiment, the driving module 12 is a totem pole structure. As an example, Figure 5 As shown, the driving module 12 includes a fifth resistor R5, a sixth resistor R6, a first driving tube Q3 and a second driving tube Q4, one end of the fifth resistor R5 is connected to the driving signal GT, and the other end is connected to the control ends of the first driving tube Q3 and the second driving tube Q4. In this example, the first driving tube Q3 is an NPN transistor, and the second driving tube Q4 is a PNP transistor; the collector of the first driving tube Q3 is connected to the power supply VCC via the sixth resistor R6, the base is connected to the fifth resistor R5, and the emitter is connected to the emitter of the second driving tube Q4 and serves as the output end of the driving module 12; the base of the second driving tube Q4 is connected to the fifth resistor R5, and the collector is grounded. In actual use, any driving structure that can amplify the power of the driving signal is applicable, not limited to this embodiment.

[0087] like Figure 5 As shown, the isolation module 13 is connected to the output end of the driving module 12 to perform high and low voltage isolation on the output signal of the driving module 12 .

[0088] Specifically, in this embodiment, the isolation module 13 includes a third diode D3, a first capacitor C1, a drive transformer T2 and a second resistor R2. The cathode of the third diode D3 is connected to the output end of the drive module 12, and the anode is connected to the first end of the primary winding of the drive transformer T2. The first capacitor C1 is connected in parallel to the two ends of the third diode D3. The second end of the primary winding of the drive transformer T2 is grounded via the second resistor R2, and the secondary winding is connected to the upper tube gate control module 14a. The output signal of the drive module 12 is AC-coupled to the primary side of the drive transformer T2 through the first capacitor C1, and the attenuation of the surge current of the second resistor R2 transmits the pulse wave through the drive transformer T2 to the secondary side of the drive transformer T2, and the signal is isolated from high and low voltage (the primary side is low voltage and the secondary side is high voltage), and the pulse signal is transmitted to the secondary side of the drive transformer T2. Any circuit structure that can achieve high and low voltage isolation and transmit the pulse signal to the secondary side of the drive transformer T2 is applicable to the isolation module 13, not limited to this embodiment.

[0089] like Figure 5 As shown, the upper tube gate control module 14a is connected to the output end of the isolation module 13, and drives the upper tube Q1 to be turned on or off based on the output signal of the isolation module 13. The lower tube gate control module 14b is connected to the output end of the driving module 12, and drives the lower tube Q2 to be turned on or off based on the output signal of the driving module 12.

[0090] Specifically, in this embodiment, the structures of the upper tube gate control module 14a and the lower tube gate control module 14b are the same. In actual use, the structures of the upper tube gate control module 14a and the lower tube gate control module 14b can be set respectively as needed. As an example, the upper tube gate control module 14a and the lower tube gate control module 14b both include an opening unit 141 and a closing unit 142. One end of the opening unit 141 receives the corresponding drive signal, and the other end is connected to the gate of the corresponding power tube, which is used to control the corresponding power tube to be turned on; the closing unit 14b is connected between the gate and the source of the corresponding power tube, and controls the corresponding power tube to be turned off based on the corresponding drive signal; wherein, the drive signal received by the opening unit 141 and the closing unit 142 in the upper tube gate control module 14a is the output signal (pulse drive signal) of the isolation module 13, and the drive signal received by the opening unit 141 and the closing unit 142 in the lower tube gate control module 14b is the output signal of the driving module 12.

[0091] More specifically, as an example, the opening unit 141 includes a third resistor R3, a second capacitor C2 and a fourth diode D4; one end of the third resistor R3 is connected to the corresponding driving signal, and the other end is connected to the anode of the fourth diode D4; the cathode of the fourth diode D4 is connected to the gate of the corresponding power tube; the second capacitor C2 is connected in parallel to the two ends of the third resistor R3. The corresponding driving signal passes through the parallel network composed of the third resistor R3 and the second capacitor C2 to perform AC acceleration and DC charging current limiting to suppress overshoot and high-frequency oscillation on the rising edge of the driving waveform; since the conduction voltage drop of the fourth diode D4 is 0.7V, the series connection of the fourth diode D4 increases the opening threshold voltage of the corresponding power tube, effectively suppressing the false triggering of the cascaded gallium nitride power tube by the interference voltage generated by the driving transformer T2.

[0092] More specifically, as an example, the shutdown unit 142 includes a fourth resistor R4, a pull-down tube Q5 and a fifth diode D5; one end of the fourth resistor R4 is connected to the gate of the corresponding power tube, and the other end is connected to the anode of the fifth diode D5 via the pull-down tube Q5; the cathode of the fifth diode D5 is connected to the source of the corresponding power tube. The junction capacitance of the cascaded gallium nitride power tube is discharged through the fourth resistor R4, the pull-down tube Q5 and the fifth diode D5. When the gate voltage of the gallium nitride power tube is less than the shutdown threshold, the gallium nitride power tube is turned off. At this time, the area of ​​the shutdown loop composed of the fourth resistor R4, the pull-down tube Q5, the fifth diode D5 and the corresponding gallium nitride power tube is the smallest, which effectively shields the influence of the interference signal on the shutdown circuit; in addition, by using the unidirectional conduction characteristic of the diode, the fifth diode D5 can effectively suppress the influence of the common mode interference generated by the output transformer T1 when the lower tube is turned off on the front-end drive circuit.

[0093] More specifically, as another implementation of the present invention, the upper tube gate control module 14a and the lower tube gate control module 14b further include a common mode interference suppression unit 143, and the common mode interference suppression unit 143 is connected between the gate and source of the corresponding power tube. Figure 5As shown, the common-mode interference suppression unit 143 includes a first transient voltage suppression diode Z1 and a second transient voltage suppression diode Z2; the cathode of the first transient voltage suppression diode Z1 is connected to the gate of the corresponding power tube, and the anode is connected to the anode of the second transient voltage suppression diode Z2; the cathode of the second transient voltage suppression diode Z2 is connected to the source of the corresponding power tube. The back-to-back connection mode of the first transient voltage suppression diode Z1 and the second transient voltage suppression diode Z2 effectively absorbs the common-mode interference from the driving transformer T2, and also absorbs the common-mode interference from the output transformer T1. In addition, the capacitive characteristics of the diode can be used to attenuate the parasitic oscillation of the driving circuit.

[0094] More specifically, as another implementation of the present invention, the upper tube gate control module 14a and the lower tube gate control module 14b further include a shutdown negative voltage generating unit, one end of which is connected to the output end of the opening unit 141 and the shutdown unit 142, and the other end is connected to the gate of the corresponding power tube. In this example, the shutdown negative voltage generating unit is implemented by a third magnetic bead L3. Further, in the case where the common-mode interference suppression unit 143 is provided, in the upper tube gate control module 14a, one end of the shutdown negative voltage generation unit is connected to the connection node of the switch unit 141, the shutdown unit 142 and the common-mode interference suppression unit 143, and the other end is connected to the gate of the upper tube Q1; in the lower tube gate control module 14b, one end of the shutdown negative voltage generation unit is connected to the connection node of the switch unit 141 and the shutdown unit 142, and the other end is connected to the connection node of the common-mode interference suppression unit 143 and the lower tube Q2; at this time, the shutdown loop includes the fourth resistor R4, the pull-down tube Q5, the fifth diode D5, the upper tube Q1 and the third magnetic bead L3. The third magnetic bead L3 absorbs electromagnetic interference and dissipates it in the form of heat energy, and at the same time, uses the back electromotive force generated by the inductor current to generate negative pressure at the bottom of the falling edge of the GaN power tube shutdown (to the gate of the GaN power tube), thereby accelerating the shutdown of the GaN power tube.

[0095] like Figure 5 As shown, the gate of the upper tube Q1 in the cascaded gallium nitride bridge power module 11 is connected to the output end of the upper tube gate control module 14a, and the gate of the lower tube Q2 is connected to the output end of the lower tube gate control module 14b, and is turned on or off based on the output signals of the upper tube gate control module 14a and the lower tube gate control module 14b.

[0096] Specifically, the structure and working principle of the cascaded gallium nitride bridge power module 11 are as described above, and will not be described in detail here. The lower tube Q2 is directly driven by the output signal of the driving module 12 without passing through the driving transformer T2. Therefore, the lower tube Q2 is turned on before the upper tube Q1 to ensure that when the upper tube Q1 is turned on, the current passes through the 5th and 4th pins of the primary winding of the output transformer T1 to store energy; at the same time, the lower tube Q2 is turned off before the upper tube Q1, such as Figure 6 As shown, the solid line is the driving voltage of the upper tube, and the dotted line is the driving voltage of the lower tube.

[0097] like Figure 7 The Vds waveform of the upper tube Q1 is shown as follows: Figure 7 The Vds waveform of the lower tube Q2 is shown. Figure 8 and Figure 7 It can be seen that the spike voltage generated by leakage inductance is almost invisible on the Vds waveform. Fig. 9 The excitation current waveform of the output transformer T1 is shown in FIG. Fig. 9 It can be seen that the waveform of the excitation current is very regular and does not generate any parasitic oscillation. In the present invention, the early opening and closing of the lower tube gives the upper tube more time to absorb the energy generated by the leakage inductance; in addition, the upper tube gate control module 14a and the lower tube gate control module 14b reduce the switching loss of the gallium nitride power tube by accelerating the negative voltage shutdown, so the output efficiency of the entire circuit is greatly improved.

[0098] like Fig.10 As shown, the present invention further provides a switching power supply, which includes: a bridge flyback topology circuit 1, a voltage input circuit 2 and a drive signal generating circuit 3.

[0099] like Fig.10 As shown, the voltage input circuit 2 converts the alternating current input voltage AC into a direct current input voltage HV.

[0100] Specifically, in this embodiment, the voltage input circuit 2 includes a fuse F1, an adjustable resistor R7, an input inductor L4, a third capacitor C3 to a ninth capacitor C9, a sixth diode D6 to a tenth diode D10, an inductor 21 and a rectifier 22. The AC input voltage AC is connected to the input end of the input inductor L4 through the fuse F1, and the adjustable resistor R7 is connected in parallel to the input end of the input inductor L4; the third capacitor C3 and the fourth capacitor C4 are connected in series and then connected in parallel to the output end of the input inductor L4, and the middle node of the third capacitor C3 and the fourth capacitor C4 is connected to the ground; the fifth capacitor C5 is connected in parallel to the output end of the input inductor L4; the cathodes of the sixth diode D6 and the seventh diode D7 are connected together, and the anodes are respectively connected to the output end of the input inductor L4; the input end of the inductor 21 is connected to the output end of the input inductor L4, and the output end is connected to the input end of the rectifier 22; the first The first end of the sixth capacitor C6 is connected to the output end of the rectifier 22, and the second end outputs the DC input voltage HV; one end of the sixth capacitor C6 is connected to the first end of the fifth inductor L5, and the other end is grounded; one end of the seventh capacitor C7 is connected to the second end of the fifth inductor L5, and the other end is grounded; one end of the seventh capacitor C7 is connected to the second end of the fifth inductor L5, and the other end is connected to the cathode of the eighth diode D8; the anode of the eighth diode D8 is grounded; the cathode of the tenth diode D10 is connected to the second end of the fifth inductor L5, and the anode is grounded via the ninth capacitor C9; the anode of the ninth diode D9 is connected to the cathode of the eighth diode D8, and the cathode is connected to the anode of the tenth diode D10. It should be noted that any circuit structure that can convert an AC input voltage into a DC input voltage is applicable to the present invention, and is not limited to this embodiment.

[0101] like Fig.10 As shown, the driving signal generating circuit 3 is connected to the voltage input circuit 2 and is used to generate the driving signal GT.

[0102] Specifically, in this embodiment, the driving signal generating circuit 3 includes a driving chip 31, an eighth resistor R8 to an eleventh resistor R11, a tenth capacitor C10 to a thirteenth capacitor C13 and an eleventh diode D11. One end of the eighth resistor R8 is connected to the cathodes of the sixth diode D6 and the seventh diode D7 in the voltage input circuit 2, and the second end is connected to the HV port of the driving chip 31; one end of the ninth resistor R9 is connected to the primary auxiliary winding of the output transformer T1, and the other end is connected to the anode of the eleventh diode D11; the cathode of the eleventh diode D11 is connected to the VDDL port of the driving chip 31; one end of the tenth capacitor C10 is connected to the VDDL port of the driving chip 31, and the other end is grounded to provide power supply VCC for the driving module; one end of the eleventh resistor R11 is connected to the current sampling end of the cascaded gallium nitride bridge power module 11 (the connection node between the first resistor R1 and the lower tube Q2), and the other end is connected to the CS port of the driving chip 31 to provide the current sampling signal IS for the driving chip 31. N; one end of the thirteenth capacitor C13 is connected to the CS port of the driver chip 31, and the other end is grounded; the GATE port of the driver chip 31 outputs the drive signal GT; the TEM port of the driver chip 31 is grounded via the tenth resistor R10 and the eleventh capacitor C11, respectively, for temperature protection; the DEM port of the driver chip 31 receives the primary auxiliary winding detection signal QRD of the output transformer T1, and demagnetization detection is implemented based on the primary auxiliary winding detection signal QRD, which can also be used for over-temperature protection; the FB port of the driver chip 31 is grounded via the twelfth capacitor C12, and also receives the output signal of the photocoupler OP, which is used to feedback the state of the output circuit 5; in this example, the driver chip 31 is a KP2202 series PWM drive controller. It should be noted that any circuit structure that can generate the drive signal GT based on the working state of the switching power supply is applicable to the present invention.

[0103] Specifically, in this embodiment, the primary auxiliary winding detection signal QRD of the output transformer T1 is provided by the detection circuit 4; as an example, the detection circuit 4 includes a twelfth resistor R12, a thirteenth resistor R13 and a fourteenth capacitor C14, the twelfth resistor R12 and the thirteenth resistor R13 are connected in series and then connected in parallel at both ends of the primary auxiliary winding (pin 7 and pin 8), and the middle node of the twelfth resistor R12 and the thirteenth resistor R13 outputs the primary auxiliary winding detection signal QRD; the 8th pin of the primary auxiliary winding is grounded, and connected to the reference ground of the output circuit 5 through the fourteenth capacitor C14. In actual use, the structure of the detection circuit 4 can be set as needed, not limited to this embodiment.

[0104] Specifically, in this embodiment, the output circuit 5 includes a fourteenth resistor R14 to a nineteenth resistor R19, a fifteenth capacitor C15 to a twentieth capacitor C20, a twelfth diode D12, a thirteenth diode D13 and a voltage reference source U1. The anode of the twelfth diode D12 is connected to the pin 1 of the secondary winding of the output transformer T1, and the output end serves as the first output end J1-1; the fourteenth resistor R14 is connected in series with the fifteenth capacitor C15, and then connected in parallel to both ends of the twelfth diode D12; the seventeenth capacitor C17, the eighteenth capacitor C18 and the nineteenth capacitor C19 are connected in parallel to both ends (pin 1 and pin 3) of the secondary winding of the output transformer T1; the anode of the thirteenth diode D13 is connected to the pin 2 of the secondary winding of the output transformer T1, and the cathode is connected to the reference ground via the sixteenth capacitor C16; the pin 3 of the secondary winding of the output transformer T1 is connected to the reference ground and serves as the second output end J1-2; the fifteenth resistor One end of R15 is connected to the cathode of the thirteenth diode D13, and the other end is connected to the cathode of the voltage reference source U1 via the photocoupler OP. The photocoupler OP emits light based on the current in the path and converts the light signal into an electrical signal to provide to the drive signal generating circuit 3; the anode of the voltage reference source U1 is connected to the reference ground; the sixteenth resistor R16, the seventeenth resistor R17 and the eighteenth resistor R18 are connected in series between the first output terminal J1-1 and the reference ground; one end of the nineteenth resistor R19 is connected to the cathode of the photocoupler OP and the input signal CATH, and the other end is connected to the connection node of the seventeenth resistor R17 and the eighteenth resistor R18 via the twentieth capacitor C20. In actual use, the structure of the output circuit 5 can be set as needed, not limited to this embodiment.

[0105] like Fig.10 As shown, the bridge flyback topology circuit 1 is connected to the voltage input circuit 2 and the drive signal generating circuit 3, and converts the DC input voltage HV into a preset output voltage based on the control of the drive signal GT.

[0106] Specifically, the structure and principle of the bridge flyback topology circuit 1 are as mentioned above and will not be elaborated here.

[0107] The switching power supply of the present invention has high efficiency; it adopts two gallium nitride series structures, has low voltage stress, the total Gong frequency can be appropriately increased, and the magnetic core material can be appropriately reduced; it has high power density and small power supply volume; the same transformer can output greater power.

[0108] In summary, the present invention provides a bridge flyback topology circuit and a switching power supply, including: an upper tube, a lower tube, a first diode, a second diode and an output transformer, wherein the upper tube and the lower tube are gallium nitride power tubes; the drain of the upper tube is connected to a DC input voltage, the source is connected to the cathode of the first diode, and the gate receives a first drive signal; the anode of the first diode is grounded; the cathode of the second diode is connected to the DC input voltage, the anode is connected to the drain of the lower tube; the source of the lower tube is grounded, and the gate is connected to a second drive signal; the primary winding of the output transformer is connected between the source of the upper tube and the drain of the lower tube, and the secondary winding is connected to the output circuit. The bridge flyback topology circuit and the switching power supply of the present invention utilize the reverse conduction characteristics of cascaded gallium nitride and two high-efficiency diodes to build a bridge circuit, effectively absorbing the energy generated by leakage inductance; no RCD absorption network is required, and the energy of the leakage inductance is recovered to the DC bus, with small size, low cost, and low power consumption; increasing the switching frequency reduces the primary inductance and weakens the leakage inductance of the transformer; effectively solving the common mode interference and standby power consumption problems. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0109] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A bridge flyback topology circuit, characterized in that: The bridge flyback topology circuit at least includes: Driving module, isolation module, upper tube gate control module, lower tube gate control module and cascaded gallium nitride bridge power module; The cascaded gallium nitride bridge power module comprises: an upper tube, a lower tube, a first diode, a second diode and an output transformer, wherein the upper tube and the lower tube are gallium nitride power tubes; the drain of the upper tube is connected to a DC input voltage, the source is connected to a cathode of the first diode, and the gate receives a first drive signal; the anode of the first diode is grounded; the cathode of the second diode is connected to the DC input voltage, and the anode is connected to the drain of the lower tube; the source of the lower tube is grounded, and the gate is connected to the second drive signal; the primary winding of the output transformer is connected between the source of the upper tube and the drain of the lower tube, and the secondary winding is connected to the output circuit; The driving module receives a driving signal and performs power amplification on the driving signal; The isolation module is connected to the output end of the driving module to perform high and low voltage isolation on the output signal of the driving module; The upper tube gate control module is connected to the output end of the isolation module, and drives the upper tube to be turned on or off based on the output signal of the isolation module; The lower tube gate control module is connected to the output end of the driving module, and drives the lower tube to be turned on or off based on the output signal of the driving module.

2. The bridge flyback topology circuit according to claim 1, characterized in that: The isolation module includes a third diode, a first capacitor, a driving transformer and a second resistor; The cathode of the third diode is connected to the output end of the driving module, and the anode is connected to the first end of the primary winding of the driving transformer; The first capacitor is connected in parallel to two ends of the third diode; The second end of the primary winding of the driving transformer is grounded via the second resistor, and the secondary winding is connected to the upper tube gate control module.

3. The bridge flyback topology circuit according to claim 1, characterized in that: The upper tube gate control module and the lower tube gate control module both include an opening unit and a closing unit; One end of the opening unit receives the corresponding driving signal, and the other end is connected to the gate of the corresponding power tube, so as to control the corresponding power tube to be turned on; The shut-off unit is connected between the gate and source of the corresponding power tube, and controls the corresponding power tube to shut down based on the corresponding driving signal.

4. The bridge flyback topology circuit according to claim 3, characterized in that: The turn-on unit includes a third resistor, a second capacitor and a fourth diode; one end of the third resistor is connected to the corresponding drive signal, and the other end is connected to the anode of the fourth diode; the cathode of the fourth diode is connected to the gate of the corresponding power tube; the second capacitor is connected in parallel to the two ends of the third resistor; and / or the turn-off unit includes a fourth resistor, a pull-down tube and a fifth diode; one end of the fourth resistor is connected to the gate of the corresponding power tube, and the other end is connected to the anode of the fifth diode via the pull-down tube; the cathode of the fifth diode is connected to the source of the corresponding power tube.

5. The bridge flyback topology circuit according to claim 3 or 4, characterized in that: The upper tube gate control module and the lower tube gate control module also include a common-mode interference suppression unit, which is connected between the gate and source of the corresponding power tube; the common-mode interference suppression unit includes a first transient voltage suppression diode and a second transient voltage suppression diode, the anodes of the first transient voltage suppression diode and the second transient voltage suppression diode are connected together, and the cathodes are respectively connected to the gate and source of the corresponding power tube.

6. The bridge flyback topology circuit according to claim 3 or 4, characterized in that: The upper tube gate control module and the lower tube gate control module also include a shutdown negative voltage generating unit, one end of the shutdown negative voltage generating unit is connected to the output end of the opening unit and the input end of the shutdown unit, and the other end is connected to the gate of the corresponding power tube; the shutdown negative voltage generating unit is a magnetic bead.

7. The bridge flyback topology circuit according to claim 1, characterized in that: The drains of the upper tube and the lower tube are respectively connected in series with magnetic beads; and / or the output transformer also includes a primary auxiliary winding, the primary auxiliary winding is connected to a detection circuit, and the detection circuit detects the voltage on the primary auxiliary winding.

8. The bridge flyback topology circuit according to claim 1 or 7, characterized in that: The cascaded gallium nitride bridge power module further includes a first resistor, which is connected in series between the source of the lower tube and the ground.

9. A switching power supply, characterized in that: The switching power supply at least comprises: a voltage input circuit, a drive signal generating circuit and a bridge flyback topology circuit as claimed in any one of claims 1 to 8; The voltage input circuit converts the AC input voltage into a DC input voltage; The driving signal generating circuit is used to generate the driving signal; The bridge flyback topology circuit is connected to the voltage input circuit and the drive signal generating circuit, and converts the DC input voltage into a preset output voltage based on the control of the drive signal.

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