An isolated drive circuit and power supply

Abstract

The utility model discloses an isolation drive circuit and power supply belong to switch drive technical field, including the primary side module, isolation module and secondary side module, the primary side module, isolation module, secondary side module, first switch tube connect gradually. The utility model discloses an isolation drive circuit and power supply, through excitation inductance and grid source capacitance resonance, excitation current charges and discharges to the grid source capacitance through the isolation module, make the current in the resistance of line itself flow reduce, namely the energy on the resistance of line itself reduce, thereby reach the purpose that reduces drive loss, thereby further improve the working efficiency and power density of power supply.

Description

Technical Field

[0001] This utility model relates to the field of switch drive technology, and in particular to an isolated drive circuit and power supply. Background Technology

[0002] Against the backdrop of continuous development in power electronics technology, power supply products are rapidly evolving towards higher frequencies, higher efficiency, and higher power density. Increasing the operating frequency is one of the key means to achieve miniaturization and high power density in power supplies. However, with the continuous increase in operating frequency, the proportion of drive circuit losses in the total power system losses increases significantly. This increase in drive losses not only poses more stringent challenges to the performance of the drive circuit, leading to increased difficulty in thermal management, but also directly reduces the overall energy conversion efficiency of the system. This technical bottleneck caused by excessively high drive losses severely restricts further increases in power supply operating frequency, thereby hindering breakthroughs in power density.

[0003] Currently, existing isolation drive circuits are not effective in controlling losses in high-frequency scenarios, making it difficult to meet the development needs of high-frequency and high-efficiency power supplies. Utility Model Content

[0004] The present invention aims to provide an isolated drive circuit and power supply with low drive loss.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] An isolation drive circuit, connected to a first switching transistor, includes a primary-side module, an isolation module, and a secondary-side module, wherein the primary-side module, the isolation module, the secondary-side module, and the first switching transistor are connected in sequence.

[0007] The isolation module includes a transformer, the two ends of the primary winding of the transformer are connected to the primary module, the first end of the first secondary winding of the transformer is connected to the first end of the first switching transistor, and the second end of the first secondary winding is connected to the first end of the second secondary winding of the transformer.

[0008] The secondary module includes a first switch and a first capacitor. The second end of the second secondary winding is connected to the first end of the first switch, the second end of the first switch is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the first end of the second secondary winding; or the first end of the second secondary winding is connected to the second end of the first switch, the first end of the first switch is connected to the second end of the first capacitor, and the first end of the first capacitor is connected to the second end of the second secondary winding; wherein, when the first switch is turned on, the current flows from the second end of the first switch to the first end of the first switch.

[0009] Furthermore, the voltage across the first capacitor is related to the number of turns of the second secondary winding.

[0010] Furthermore, a gate-source capacitor is connected in parallel between the first and second terminals of the first switching transistor. The duty cycle of the voltage across the gate-source capacitor is related to the duration of the voltage across the primary winding being positive on top and negative on the bottom.

[0011] Furthermore, the energy recovery effect, the switching speed of the first switching transistor, and the excitation inductance of the transformer, the circuit of the primary-side module, and the driving resistance of the first switching transistor are all related.

[0012] Furthermore, when multiple isolation drive circuits are used to drive multiple switching transistors, each isolation drive circuit drives one switching transistor.

[0013] In one specific embodiment, the primary-side module is a half-bridge topology, a symmetrical half-bridge topology, a full-bridge topology, an active clamp forward topology, or a push-pull topology.

[0014] In one specific embodiment, the first switch is a diode or a MOSFET.

[0015] In one specific embodiment, when the first switch is a diode, the first end of the first switch is its cathode, and the second end of the first switch is its anode.

[0016] In one specific embodiment, the first switch is a silicon switch, a gallium nitride switch, or a silicon carbide switch.

[0017] This utility model also provides a power supply, including the above-mentioned isolated drive circuit, and further including a main power board and a signal board, wherein the transformer is disposed between the signal board and the main power board or disposed on the main power board.

[0018] Beneficial effects: This utility model provides an isolated drive circuit and power supply. By resonating the excitation inductor with the gate-source capacitor, the excitation current charges and discharges the gate-source capacitor through the isolation module, thereby reducing the current flowing through the resistance of the circuit itself, that is, reducing the energy lost in the resistance of the circuit itself, thereby achieving the purpose of reducing drive loss, and further improving the working efficiency and power density of the power supply.

[0019] To make the above-mentioned features and advantages of the utility model more apparent and understandable, specific embodiments are described below, and detailed descriptions are provided in conjunction with the accompanying drawings. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a first specific embodiment of an isolation drive circuit according to the present invention.

[0021] Figure 2This is a schematic diagram of the structure of a second specific embodiment of an isolation drive circuit according to the present invention.

[0022] Figure 3 This is a schematic diagram of the structure of a third specific embodiment of an isolation drive circuit according to the present invention.

[0023] Figure 4 This is a circuit diagram of the first specific embodiment of the primary-side module.

[0024] Figure 5 This is a circuit diagram of the second specific embodiment of the primary-side module.

[0025] Figure 6 This is a circuit diagram of the third specific embodiment of the primary-side module.

[0026] Figure 7 This is a circuit diagram of the fourth specific embodiment of the primary-side module.

[0027] Figure 8 This is a circuit diagram of the fifth specific embodiment of the primary-side module.

[0028] Figure 9 This is a schematic diagram of the structure of a first specific embodiment of a power supply according to the present invention.

[0029] Figure 10 This is a schematic diagram of the structure of a second specific embodiment of the power supply of this utility model.

[0030] Figure 11 In the figure, (a) represents the gate-source capacitance C. gs1 Voltage V at both ends gs1 The waveform is at zero level when turned off. Figure 11 In the diagram, (b) represents the gate-source capacitance C. gs1 Voltage V at both ends gs1 The waveform is a negative level when it is turned off.

[0031] In the accompanying drawings, similar reference numerals refer to the same elements. Detailed Implementation

[0032] To make the objectives and technical solutions of the present utility model clearer, the technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0033] Figure 1 This is a circuit diagram of a first specific embodiment of an isolation drive circuit according to this utility model. Figure 1 As shown, the present invention provides an isolation drive circuit 11 connected to a switching transistor Q1 for driving the switching transistor Q1.

[0034] Furthermore, the isolation drive circuit 11 of this utility model includes a primary-side module 111, an isolation module 112, and a secondary-side module 113, with an input voltage V. IN The primary side module 111, the isolation module 112, the secondary side module 113, and the switch Q1 are connected in sequence.

[0035] More specifically, the primary-side module 111 will input voltage V IN The voltage is converted into AC voltage and transmitted to isolation module 112. Isolation module 112 isolates and converts this AC voltage and transmits it to secondary module 113. After being converted by secondary module 113, it drives switch Q1.

[0036] Furthermore, the isolation module 112 includes a transformer T1, the two ends of the primary winding N1 of the transformer T1 are connected to the primary module 111, the first end of the secondary winding N2 of the transformer T1 is connected to the first end of the switching transistor Q1, the second end of the secondary winding N2 is connected to the first end of the secondary winding N3, and the second end of the secondary winding N3 is connected to the second end of the switching transistor Q1.

[0037] More specifically, the magnetizing inductance L of transformer T1 m It is connected in parallel across the two ends of the primary winding N1.

[0038] Furthermore, in Figure 1 In a specific embodiment, the secondary module 113 includes a switch D1 and a capacitor C1. The second end of the secondary winding N3 is connected to the first end of the switch D1, the second end of the switch D1 is connected to the first end of the capacitor C1, and the second end of the capacitor C1 is connected to the first end of the secondary winding N3. When the switch D1 is turned on, the current flows from the second end of the switch D1 to the first end of the switch D1.

[0039] In one specific embodiment, switch D1 may be a diode or a MOSFET, etc., but this application is not limited thereto.

[0040] More specifically, when switch D1 is a diode, the first terminal of switch D1 is its cathode, and the second terminal of switch D1 is its anode.

[0041] More specifically, a gate-source capacitor C is connected in parallel between the first and second terminals of the switching transistor Q1. gs1 .

[0042] Optionally, the gate-source capacitance C gs1 It can be the gate-source capacitance of the switching transistor Q1 itself, or it can be an external capacitor.

[0043] Optionally, the switching transistor Q1 can be a silicon (Si) switching device, a gallium nitride (GaN) switching device, a silicon carbide (SiC) switching device, an IGBT, etc., and this application is not limited to this.

[0044] In one specific embodiment, when the switch Q1 is a MOSFET, the first terminal of the switch Q1 is its gate, and the second terminal of the switch Q1 is its source.

[0045] The following is combined Figure 1 Continuing with the description of the working principle of the isolation drive circuit of this utility model, when the voltage across the primary winding N1 is positive at the top and negative at the bottom, the secondary windings N2 and N3 also induce a voltage that is positive at the top and negative at the bottom. The secondary windings N2 and N3 together provide the drive voltage for the switching transistor Q1, and the secondary winding N3 charges the capacitor C1 through diode D1. At this time, the gate-source capacitor C... gs1 Voltage V at both ends gs1 It equals the sum of the voltage across the secondary winding N2 and the voltage across the capacitor C1, when the gate-source capacitance C gs1 Voltage V at both ends gs1 When the voltage across the primary winding N1 is charged to above the threshold voltage of the switching transistor Q1, Q1 turns on. When the voltage across the primary winding N1 is positive at the bottom and negative at the top, the secondary windings N2 and N3 induce a voltage that is positive at the bottom and negative at the top. Due to the presence of diode D1, the secondary winding N2 and capacitor C1 affect the gate-source capacitance C of the switching transistor Q1. gs1 This forms a discharge circuit, at which point the gate-source capacitance C gs1 Voltage V at both ends gs1 The voltage across capacitor C1 is equal to the difference between the voltage across the secondary winding N2, when the gate-source capacitance C gs1 Voltage V at both ends gs1 When the voltage is discharged below the threshold voltage of switch Q1, switch Q1 turns off. Due to the presence of diode D1, the voltage across capacitor C1 remains positive.

[0046] More specifically, in an isolated drive circuit of this invention, the magnetizing inductor L... m With gate-source capacitance C gs1 Resonance occurs when the excitation current passes through isolation module 112 to the gate-source capacitor C. gs1 Charging and discharging reduce the current flowing through the circuit's inherent resistance, thus reducing energy loss across the circuit's resistance and consequently reducing drive losses. This further improves the power supply's efficiency and power density. Furthermore, the voltage V across capacitor C1... C1 Related to the number of turns in the secondary winding N3, adjusting the number of turns in the secondary winding N3 can adjust the voltage across capacitor C1, thereby adjusting the gate-source capacitance C. gs1 Voltage V at both ends gs1 .like Figure 11 As shown in (a), the gate-source capacitance Cgs1 Voltage V at both ends gs1 It can be at zero level when turned off; such as Figure 11 As shown in (b), the gate-source capacitance C gs1 Voltage V at both ends gs1 It can be a negative level when turned off.

[0047] Furthermore, the gate-source capacitance C gs1 Voltage V at both ends gs1 The duty cycle is related to the duration of the voltage across the primary winding N1 being positive when it is positive and negative when it is negative. By adjusting the drive of the switch in the primary module 111, the duration of the voltage across the primary winding N1 being positive when it is positive and negative when it is negative can be adjusted, thereby flexibly adjusting the gate-source capacitance C. gs1 Voltage V at both ends gs1 Duty cycle.

[0048] Furthermore, the magnetizing inductance L m With gate-source capacitance C gs1 Resonance causes the driving energy to affect the gate-source capacitance C. gs1 Transfer or from gate-source capacitance C gs1 The energy recovery process involves adjusting the switching speed of the switching transistor, specifically related to the transformer's magnetizing inductance, the primary-side module circuitry, and the drive resistance of the switching transistor Q1. The energy recovery efficiency is influenced by the adjustable gate-source capacitance C. gs1 The speed and effectiveness of energy recovery from the drive system can be improved, and the switching speed of the switching transistor can be adjusted. For example... Figure 11 As shown in (a) and (b), the turn-off waveform of the switching transistor is divided into two segments. The first segment is the recovery of drive energy by the magnetizing inductor until the gate-source capacitance C... gs1 Voltage V at both ends gs1 The discharge is brought below the target turn-off voltage of switch Q1; the second stage is when the gate-source capacitance C... gs1 Voltage V at both ends gs1 When the voltage is discharged below the target turn-off voltage of the switch Q1, the switch is hard-turned off, thereby improving the turn-off speed of the switch.

[0049] Furthermore, the magnetizing inductance L of transformer T1 m This is related to the dead-time setting of the switching transistor in the primary side module 111.

[0050] Figure 2 This is a circuit diagram of a second specific embodiment of an isolation drive circuit according to this utility model. Figure 2 As shown, the present invention provides an isolation drive circuit 21 connected to a switching transistor Q1 for driving the switching transistor Q1.

[0051] Furthermore, the isolation drive circuit 21 includes a primary-side module 211, an isolation module 212, and a secondary-side module 213, with an input voltage V. INThe primary side module 211, the isolation module 212, the secondary side module 213, and the switch Q1 are connected in sequence.

[0052] Furthermore, in Figure 2 In a specific embodiment, the secondary module 213 includes a switch D1 and a capacitor C1. The first end of the secondary winding N3 is connected to the second end of the switch D1, the first end of the switch D1 is connected to the second end of the capacitor C1, the first end of the capacitor C1 is connected to the second end of the secondary winding N3, and the current flow direction when the switch D1 is turned on is from the second end of the switch D1 to the first end of the switch D1.

[0053] In one specific embodiment, switch D1 may be a diode or a MOSFET, etc., but this application is not limited thereto.

[0054] More specifically, when switch D1 is a diode, the first terminal of switch D1 is its cathode, and the second terminal of switch D1 is its anode.

[0055] exist Figure 2 In a specific embodiment, the isolation module 212 and Figure 1 The structure and function of the middle isolation module 112 are the same, and will not be described again here.

[0056] Figure 3 This is a circuit diagram of a third specific embodiment of an isolation drive circuit according to this utility model. Figure 3 As shown, isolation drive circuit 31 is connected to switch Q1 and is used to drive switch Q1; isolation drive circuit 32 is connected to switch Q2 and is used to drive switch Q2. Switch Q1 and switch Q2 form a half-bridge topology.

[0057] Furthermore, the isolation drive circuit 31 includes a primary-side module 311, an isolation module 312, and a secondary-side module 313, with an input voltage V. IN The primary side module 311, the isolation module 312, the secondary side module 313, and the switch Q1 are connected in sequence.

[0058] Furthermore, the isolation drive circuit 32 includes a primary-side module 321, an isolation module 322, and a secondary-side module 323, with an input voltage V. IN The primary side module 321, the isolation module 322, the secondary side module 323, and the switch Q2 are connected in sequence.

[0059] exist Figure 3 In a specific embodiment, isolation module 312, isolation module 322 and Figure 1 The structure and function of the middle isolation module 112 are the same, and will not be described again here; the secondary side modules 313 and 323 are the same as those in the middle isolation module 112. Figure 1 The structure and function of the secondary side module 113 are the same, and will not be described again here.

[0060] Furthermore, when using the isolation drive circuit of this invention to drive a half-bridge topology, the gate-source capacitance C gs1 Voltage V at both ends gs1 Gate-source capacitance C gs2 Voltage V at both ends gs2 The duty cycle is related to the duration of the voltage across the primary winding N1 being positive at the top and negative at the bottom. By adjusting the drive of the switches in primary module 311 and primary module 321, the gate-source capacitance C can be adjusted. gs1 Voltage V at both ends gs1 Gate-source capacitance C gs2 Voltage V at both ends gs2 The dead time is used to cooperate with the main power circuit to achieve zero-voltage turn-on (ZVS) of switching transistors Q1 and Q2.

[0061] Alternatively, in addition to Figure 3 In addition to the two switching transistors shown in the specific embodiment, multiple isolation driving circuits can be used to drive multiple switching transistors. Each isolation driving circuit drives one switching transistor. By adjusting the driving of the switches in the primary side module of each isolation driving circuit, the voltage across the gate-source capacitor of each switching transistor can be adjusted, thereby cooperating with the main power circuit to meet the driving requirements of the switching transistors.

[0062] Furthermore, Figures 1 to 3 The primary edge module can be implemented in various forms, including but not limited to half-bridge topology, symmetric half-bridge topology, full-bridge topology, active clamp forward topology, push-pull topology, etc., and this application is not limited to these.

[0063] like Figure 4 As shown, the primary edge module can be a half-bridge topology. More specifically, Figure 4 The primary-side module 411 includes switching transistors Q3 and Q4 and capacitor C2. Switching transistors Q3 and Q4 are connected in series and connected to the input voltage V. IN In parallel connection, the midpoint of the series connection between switching transistors Q3 and Q4 is connected to the first terminal of capacitor C2, and the second terminal of capacitor C2, switching transistor Q4, and input voltage V are connected to each other. IN The connection midpoint is connected to the isolation module 412.

[0064] like Figure 5 As shown, the primary edge module can be a symmetrical half-bridge topology. More specifically, Figure 5 The primary-side module 511 includes switching transistors Q5 and Q6, capacitors C3 and C4. Switches Q5 and Q6 are connected in series and connected to the input voltage V. IN In parallel, capacitors C3 and C4 are connected in series and then connected to the input voltage V. IN The series midpoints of switching transistors Q5 and Q6, and the series midpoints of capacitors C3 and C4 are connected in parallel to isolation module 512.

[0065] like Figure 6 As shown, the primary edge module can be a full-bridge topology. More specifically, Figure 6 The primary-side module 611 includes switching transistors Q7, Q8, Q9, and Q1. 10 The capacitor C5, the switching transistors Q7 and Q8 are connected in series with the input voltage V. IN In parallel, switching transistors Q9 and Q... 10 After being connected in series with the input voltage V IN In parallel, the midpoint of the series connection between switching transistors Q7 and Q8 is connected to the first terminal of capacitor C5, and the second terminal of capacitor C5 is connected to switching transistors Q9 and Q8. 10 The series midpoint is connected to the isolation module 612.

[0066] like Figure 7 As shown, the primary edge module can be an active clamp forward topology. More specifically, Figure 7 The primary-side module 711 includes the switching transistor Q. 11 Switching transistor Q 12 The first terminal of the primary winding N1, along with capacitor C6, is connected to the input voltage V. IN The positive terminal of the switch Q 12 Connected to the second terminal of the primary winding N1 and the input voltage V IN Between the negative terminals, the switching transistor Q 11 It is connected in series with capacitor C6 and then in parallel with switching transistor Q. 12 Both ends.

[0067] like Figure 8 As shown, the primary edge module can be a push-pull topology. More specifically, Figure 8 The primary-side module 811 includes the switching transistor Q. 13 With the switching transistor Q 14 The input voltage V is connected to the midpoint of the primary winding N1. IN The positive terminal of the switch Q 13 The switching transistor Q is connected between the first terminal of the primary winding N1 and ground. 14 It is connected between the second terminal of the primary winding N1 and ground. In this specific embodiment, the magnetizing inductor L m1 With excitation inductance L m2 After being connected in series, they are connected in parallel across the two ends of the primary winding N1.

[0068] Furthermore, Figures 1 to 8 In practice, the transformer T1 can be implemented in various forms, and the winding form and magnetic core form of the transformer T1 are not restricted.

[0069] like Figure 9 As shown, in one specific embodiment, the present invention also provides a power supply 9, including a main power board 91, a signal board 92 and a transformer 93, wherein the transformer 93 is disposed between the signal board 92 and the main power board 91.

[0070] Furthermore, the transformer 93 includes a magnetic core 931 and a winding 932. The winding 932 is disposed in the space enclosed by the magnetic core 931. The winding 932 forms a circuit with the signal board 92 and the main power board 91 through the connector 94. The magnetic core 931 is attached to the outside of the connector 94.

[0071] In this specific embodiment, Figures 1 to 8 Transformer T1 in the middle corresponds to Figure 9 Transformer 93 in the middle.

[0072] Alternatively, winding 932 can be in the form of a coil winding or a circuit board (PCB) winding.

[0073] Optionally, Figures 1 to 8 The primary side module, isolation module, and secondary side module can be set on the signal board 92.

[0074] Optionally, the main power circuit of the power supply 9 can be set on the main power board 91.

[0075] like Figure 10 As shown, in another specific embodiment, the present invention also provides a power supply 10, including a main power board 101 and a transformer 103, wherein the transformer 103 is disposed on the main power board 101.

[0076] Furthermore, the transformer 103 includes a magnetic core 1031 and a winding 1032. The winding 1032 is disposed in the space enclosed by the magnetic core 1031, and the magnetic core 1031 is fastened to the main power board 101.

[0077] In this specific embodiment, Figures 1 to 8 Transformer T1 in the middle corresponds to Figure 10 Transformer 103 in the middle.

[0078] Alternatively, the winding 1032 can be in the form of a coil winding or a circuit board (PCB) winding.

[0079] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

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