Power tube peak absorption circuit, switching circuit and charging control method

Abstract

The invention relates to the technical field of power supplies, in particular to a power tube peak absorption circuit, a switching circuit and a charging control method. Comprising an MOS tube, an energy storage module, a current limiting module and an anti-countercurrent module, the input end of the energy storage module is connected to the drain electrode of the power tube, the output end of the energy storage module is connected with the drain electrode of the MOS tube, the source electrode of the MOS tube is connected with one end of the current limiting module, the other end of the current limiting module is connected with the positive electrode of the anti-countercurrent module, and the negative electrode of the anti-countercurrent module is connected to the source electrode of the power tube. The grid electrode of the MOS tube and the grid electrode of the power tube are connected with an external controller. Before the power tube is turned on, the MOS tube in the power tube peak absorption circuit is turned on, the energy storage module of the power tube peak absorption circuit is charged, and after the energy storage module of the power tube peak absorption circuit is fully charged for RC charging time, the power tube is controlled to be turned on, so that the voltage difference between the drain electrode and the source electrode of the power tube can be effectively reduced, and the peak absorption function is realized; the scheme is lower in efficiency loss and lower in cost.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a power tube peak absorption circuit, a switch circuit and a charging control method. Background Art

[0002] In the current power module system, many topologies of the switching circuit require the use of switching power tubes. The rapid switching of the switching power tubes will cause severe voltage stress spikes to the switching power tubes. The traditional RC absorption circuit loses efficiency, and the greater the power, the greater the energy that the RC absorption circuit needs to absorb, which will make the efficiency lower. In addition, the traditional RC absorption circuit will generate severe heat after absorbing more energy, and the resistance and capacitance values ​​in the RC circuit are difficult to calculate, and actual experiments are needed for adjustment.

[0003] Therefore, it is very important for technicians in this field to design a power tube absorption circuit, a switching circuit and a charging control method power supply with higher absorption efficiency and low cost. Summary of the invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a power tube absorption circuit, a switch circuit and a charging control method with higher absorption efficiency and low cost, so as to solve the problems of low efficiency, severe heat generation and difficult calculation of values ​​in the prior art.

[0005] The present invention discloses a power tube peak absorption circuit, which comprises: a MOS tube, an energy storage module, a current limiting module and an anti-backflow module, wherein the input end of the energy storage module is connected to the drain of the power tube, the output end of the energy storage module is connected to the drain of the MOS tube, the source of the MOS tube is connected to one end of the current limiting module, the other end of the current limiting module is connected to the positive electrode of the anti-backflow module, the negative electrode of the anti-backflow module is connected to the source of the power tube, and the gate of the MOS tube and the gate of the power tube are both connected to an external controller.

[0006] Optionally, the current limiting module is a current limiting resistor.

[0007] Optionally, the backflow prevention module is a backflow prevention diode.

[0008] Optionally, the energy storage module is a capacitor.

[0009] In order to solve the problems existing in the prior art, the present invention also provides a switching circuit, which includes: a controller, an input source, a main power tube, an inductor and an output source, the drain of the main power tube is connected to the output source, the source of the main power tube is connected to the input end of the inductor, the output end of the inductor is connected to the output source, and the gate of the main power tube is connected to the controller, wherein a main power tube peak absorption circuit is provided on the main power tube, and the main power tube peak absorption circuit is the power tube peak absorption circuit as described above.

[0010] Optionally, a synchronous freewheeling tube is also included, wherein the drain of the synchronous freewheeling tube is connected between the source of the main power tube and the input end of the inductor, the source of the synchronous freewheeling tube is grounded, and the gate of the synchronous freewheeling tube is connected to the controller.

[0011] Optionally, a synchronous freewheeling tube peak absorption circuit is provided on the synchronous freewheeling tube, and the synchronous freewheeling tube peak absorption circuit is the same as the main power tube peak absorption circuit.

[0012] Optionally, a freewheeling diode is further included, wherein the anode of the freewheeling diode is connected to the output source, and the cathode of the freewheeling diode is grounded.

[0013] In order to solve the problems existing in the prior art, the present invention further provides a charging control method for controlling the switch circuit as described above, and the scheme thereof comprises the following steps:

[0014] Control the MOS tube in the main power tube peak absorption circuit to turn on, so as to charge the energy storage module in the main power tube peak absorption circuit;

[0015] After charging is completed according to the RC charging time, the main power tube is controlled to turn on;

[0016] And, controlling the MOS tube in the synchronous freewheeling tube peak absorption circuit to turn on, so as to charge the energy storage module in the synchronous freewheeling tube peak absorption circuit;

[0017] After charging is completed according to the RC charging time, the synchronous freewheeling tube is controlled to turn on.

[0018] Optionally, the energy storage module of the power tube peak absorption circuit is a capacitor, the current limiting module of the power tube peak absorption circuit is a current limiting resistor, and the calculation formula of the RC charging time is:

[0019] t=RC×Ln(Vcc-V0)

[0020] Wherein, t is the RC charging time, V0 is the initial voltage value of the capacitor, Vcc is the target voltage value of the capacitor charging, R is the resistance value of the current limiting resistor, and C is the capacitance value of the capacitor.

[0021] Compared with the prior art, the power tube peak absorption circuit provided by the embodiment of the present invention has the beneficial effect that: by designing a power tube peak absorption circuit, including a MOS tube, an energy storage module, a current limiting module and an anti-backflow module, the input end of the energy storage module is connected to the drain of the power tube, the output end of the energy storage module is connected to the drain of the MOS tube, the source of the MOS tube is connected to one end of the current limiting module, the other end of the current limiting module is connected to the positive electrode of the anti-backflow module, the negative electrode of the anti-backflow module is connected to the source of the power tube, and the gate of the MOS tube and the gate of the power tube are both connected to an external controller; by turning on the MOS tube in the power tube peak absorption circuit before the power tube is turned on, and charging the energy storage module in the power tube peak absorption circuit, when the energy storage module of the power tube peak absorption circuit is charged for the full RC charging time, the power tube is controlled to be turned on, which can effectively reduce the voltage difference between the drain and the source of the power tube, thereby realizing the peak absorption function, and the scheme has low efficiency loss and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in which:

[0023] Figure 1 is a circuit diagram of a power tube peak absorption circuit provided by an embodiment of the present invention;

[0024] Figure 2 is a circuit diagram of a switch circuit provided by an embodiment of the present invention;

[0025] Figure 3 is a flow chart of a charging control method provided by an embodiment of the present invention.

[0026] The reference numerals in the figures are:

[0027] 100, MOS tube; 200, energy storage module; 300, current limiting module; 400, anti-backflow module; 500, external controller; Q1, power tube;

[0028] 10. Controller; 20. Input source; Q2. Main power tube; L. Inductor; 30. Output source; R1. First resistor; C1. First capacitor; Q4. First MOS tube; D1. First diode; R2. Second resistor; C2. Second capacitor; Q5. Second MOS tube; D2. Second diode; Q3. Synchronous freewheeling tube; D3. Freewheeling diode. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Now, in conjunction with the accompanying drawings, the preferred embodiments of the present invention are described in detail.

[0030] like Figure 1As shown, the present invention provides a specific embodiment of a power tube peak absorption circuit.

[0031] A power tube peak absorption circuit, reference Figure 1 The power tube peak absorption circuit includes: a MOS tube 100, an energy storage module 200, a current limiting module 300 and an anti-backflow module 400. The input end of the energy storage module 200 is connected to the drain D of the power tube Q1, the output end of the energy storage module 200 is connected to the drain D of the MOS tube 100, the source S of the MOS tube 100 is connected to one end of the current limiting module 300, the other end of the current limiting module 300 is connected to the positive electrode of the anti-backflow module 400, the negative electrode of the anti-backflow module 400 is connected to the source S of the power tube, and the gate G of the MOS tube 100 and the gate G of the power tube are both connected to the external controller 500.

[0032] Specifically, refer to Figure 1 The power tube peak absorption circuit is used to absorb the voltage stress spike caused by the power tube Q1 during the switching process. The principle is that before the power tube Q1 is turned on, the MOS tube 100 in the power tube peak absorption circuit is controlled to be turned on, so as to charge the energy storage module 200 in the power tube peak absorption circuit until the charging voltage of the energy storage module 200 is close to the input voltage of the power tube Q1, so that the voltage difference between the drain D of the power tube Q1 and the source S of the power tube Q1 is reduced, and the electric field strength on the power tube Q1 can be reduced. At this time, the power tube Q1 is turned on again, which can effectively suppress the voltage stress spike.

[0033] Further, refer to Figure 1 The current limiting module 300 in the power tube peak absorption circuit is used to limit the current and charge the energy storage module 200 in the power tube peak absorption circuit. The anti-backflow module 400 in the power tube peak absorption circuit is used to prevent the power tube Q1 from being damaged when the current flows in the reverse direction. The power tube can usually only withstand current in one direction. If the reverse current passes through the power tube, it may cause device breakdown or damage. The anti-backflow module 400 in the power tube peak absorption circuit can effectively protect it.

[0034] At present, many topologies of power circuits in switching power supply systems require the use of switching power tubes. The rapid switching of the switching power tubes will cause severe voltage stress spikes to the switching power tubes, and an instantaneous voltage increase will suddenly appear in the circuit. Although the duration of the voltage stress spike is not long, it can still cause damage or interference to components.

[0035] In this embodiment, a power tube peak absorption circuit is designed, including a MOS tube 100, an energy storage module 200, a current limiting module 300 and an anti-backflow module 400, the input end of the energy storage module 200 is connected to the drain D of the power tube, the output end of the energy storage module 200 is connected to the drain D of the MOS tube 100, the source S of the MOS tube 100 is connected to one end of the current limiting module 300, the other end of the current limiting module 300 is connected to the positive electrode of the anti-backflow module 400, and the negative electrode of the anti-backflow module 400 is connected to the source of the power tube. The gate S of the MOS tube 100 and the gate G of the power tube are all connected to the external controller 500; before the power tube is turned on, the MOS tube 100 in the power tube peak absorption circuit is turned on first, and the energy storage module 200 in the power tube peak absorption circuit is charged through the current limiting module 300 in the power tube peak absorption circuit, so that the voltage difference between the source S and the drain D of the power tube is reduced, and the voltage stress spike is effectively suppressed; and the reverse current is prevented from breaking through the power tube through the anti-backflow module 400, so that the circuit is more stable and safe.

[0036] In one embodiment, the current limiting module 300 is a current limiting resistor; one end of the current limiting resistor is connected to the source S of the MOS tube 100, and the other end of the current limiting resistor is connected to the anti-backflow module 400. The current limiting resistor is connected in series in the circuit to limit the current size, thereby preventing excessive current from damaging the energy storage module 200.

[0037] In one embodiment, the anti-backcurrent module 400 is an anti-backcurrent diode; the positive pole of the anti-backcurrent diode is connected to one end of the current limiting resistor, and the negative pole of the anti-backcurrent diode is connected to the source S of the power tube to prevent the reverse flow of current, thereby preventing the reverse current from causing reverse impact on the circuit or components and damaging the components.

[0038] In one embodiment, the energy storage module 200 is a capacitor, one end of which is connected to the drain D of the power tube, and the other end of which is connected to the drain D of the MOS tube 100, so as to be charged before the power tube is turned on, so that the voltage difference between the drain D of the power tube and the source S of the power tube is reduced, thereby reducing the voltage stress spike of the power tube when switching.

[0039] like Figure 2 As shown, the present invention also provides a specific embodiment of a switch circuit.

[0040] A switching circuit, referring to Figure 2The switch circuit includes: a controller 10, an input source 20, a main power tube Q2, an inductor L and an output source 30, the drain D of the main power tube Q2 is connected to the output source 30, the source S of the main power tube Q2 is connected to the input end of the inductor L, the output end of the inductor L is connected to the output source 30, and the gate G of the main power tube Q2 is connected to the controller 10, wherein a main power tube peak absorption circuit is provided on the main power tube Q2, and the main power tube peak absorption circuit is the power tube peak absorption circuit described above.

[0041] Specifically, refer to Figure 2 The switching circuit is a BUCK synchronous rectification circuit, which is a common power electronic circuit topology and is often used in a buck converter. It includes a controller 10, an input source 20, a main power tube Q2, an inductor L, and an output source 30. The input source 20 is used for voltage input, and the output source 30 is used for voltage output. The main power tube Q2 is a switching power tube used to turn on or off the power supply circuit. The controller 10 is used to control the switch of the main power tube Q2, so that the power supply circuit is turned on or off.

[0042] Further, refer to Figure 2 A main power tube peak absorption circuit is provided on the main power tube Q2. The main power tube peak absorption circuit is the power tube peak absorption circuit as described above, that is, the main power tube peak absorption circuit includes a first resistor R1, a first capacitor C1, a first MOS tube Q4 and a first diode D1. One end of the first capacitor C1 is connected between the input source 20 and the drain D of the main power tube Q2, the other end of the first capacitor C1 is connected to the drain D of the first MOS tube Q4, the source S of the first MOS tube Q4 is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the positive electrode of the first diode D1, and the negative electrode of the first diode D1 is connected between the source S of the main power tube Q2 and the inductor L, so as to absorb the voltage stress spike of the main power tube Q2 during switching, thereby protecting the main power tube Q2 from breakdown, and making the switch circuit more stable and safe.

[0043] In one embodiment, reference Figure 2 The switch circuit also includes a synchronous freewheeling tube Q3, a drain D of the synchronous freewheeling tube Q3 is connected between the source S of the main power tube Q2 and the input end of the inductor L, the source S of the synchronous freewheeling tube Q3 is grounded, and the gate G of the synchronous freewheeling tube Q3 is connected to the controller 10. The synchronous freewheeling tube Q3 is used to switch synchronously according to the control signal to realize rectification of the output voltage.

[0044] Further, refer to Figure 2A synchronous freewheeling tube peak absorption circuit is provided on the synchronous freewheeling tube Q3, and the synchronous freewheeling tube peak absorption circuit is the same as the main power tube peak absorption circuit; that is, the synchronous freewheeling tube peak absorption circuit includes a second resistor R2, a second capacitor C2, a second MOS tube Q5 and a second diode D2, one end of the second capacitor C2 is connected between the source S of the main power tube Q2 and the drain D of the synchronous freewheeling tube Q3, the other end of the second capacitor C2 is connected to the drain D of the second MOS tube Q5, the source S of the second MOS tube Q5 is connected to one end of the second resistor R2, the other end of the second resistor R2 is connected to the positive electrode of the second diode D2, and the negative electrode of the second diode D2 is connected to the source S of the synchronous freewheeling tube Q3, so as to absorb the voltage stress spike of the synchronous freewheeling tube Q3 during switching, thereby protecting the synchronous freewheeling tube Q3 from breakdown, making the switching circuit more stable and safe.

[0045] In one embodiment, reference Figure 2 The switch circuit also includes a freewheeling diode D3, the anode of the freewheeling diode D3 is connected to the output source 30, the cathode of the freewheeling diode D3 is connected to the source S of the synchronous freewheeling tube Q3, and is grounded.

[0046] Specifically, refer to Figure 2 In the BUCK synchronous rectification circuit, the inductor L can play a role in limiting the current when the main power tube Q2 is turned on. When the main power tube Q2 is turned on, the inductor L will store energy, thereby limiting the sudden increase of current to protect other components in the power supply circuit from the impact of excessive current. The inductor L can also reduce the ripple of the output voltage. When the main power tube Q2 is turned off, the inductor L can continue to provide current through the freewheeling diode D3, thereby smoothing the output voltage to reduce voltage fluctuations. In addition, the inductor L can also store energy in the main power tube Q2 conduction device. When the main power tube Q2 is turned off, the inductor L can release the stored energy to ensure continuous power supply to the load, thereby maintaining the stability of the output voltage.

[0047] like Figure 3 As shown, the present invention also provides a specific embodiment of a charging control method.

[0048] A charging control method for controlling the switch circuit as described above, referring to Figure 3 The charging control method specifically includes the following steps:

[0049] S11, controlling the MOS tube in the main power tube peak absorption circuit to turn on, so as to charge the energy storage module in the main power tube peak absorption circuit;

[0050] S12, after charging is completed according to the RC charging time, the main power tube is controlled to turn on;

[0051] S21, controlling the MOS tube in the synchronous freewheeling tube peak absorption circuit to turn on, so as to charge the energy storage module in the synchronous freewheeling tube peak absorption circuit;

[0052] S22, after charging is completed according to the RC charging time, control the synchronous freewheeling tube to turn on.

[0053] Specifically, refer to Figure 2 and Figure 3 Before the main power tube Q2 is turned on, the MOS tube Q4 in the main power tube peak absorption circuit is controlled to be turned on first, so as to charge the energy storage module (first capacitor C1) in the main power tube peak absorption circuit until the charging voltage of the energy storage module (first capacitor C1) is close to the input voltage of the main power tube Q2, so that the voltage difference between the drain D of the main power tube Q2 and the source S of the main power tube Q2 is reduced, and the electric field strength on the main power tube Q2 can be reduced. At this time, the main power tube Q2 is turned on again, thereby effectively suppressing the voltage stress spike.

[0054] Similarly, before the synchronous freewheeling tube Q3 is turned on, the MOS tube Q5 in the synchronous freewheeling tube peak absorption circuit is controlled to be turned on first, so as to charge the energy storage module (the second capacitor C2) in the synchronous freewheeling tube peak absorption circuit until the charging voltage of the energy storage module (the second capacitor C2) is close to the input voltage of the synchronous freewheeling tube Q3, so that the voltage difference between the drain D of the synchronous freewheeling tube Q3 and the source S of the synchronous freewheeling tube Q3 is reduced, and the electric field strength on the synchronous freewheeling tube Q3 can be reduced. At this time, the synchronous freewheeling tube Q3 is turned on again, thereby effectively suppressing the voltage stress spike.

[0055] In one embodiment, the energy storage module of the power tube peak absorption circuit is a capacitor, the current limiting module of the power tube peak absorption circuit is a current limiting resistor, and the calculation formula of the RC charging time is:

[0056] t=RC×Ln(Vcc-V0)

[0057] Wherein, t is the RC charging time, V0 is the initial voltage value of the capacitor, Vcc is the target voltage value of the capacitor charging, R is the resistance value of the current limiting resistor, and C is the capacitance value of the capacitor.

[0058] Specifically, the RC charging time is determined according to the capacitance of the capacitor in the power tube spike absorption circuit and the resistance of the current limiting resistor in the power tube spike absorption circuit. The purpose of charging the energy storage module until it is fully charged is to make the charging voltage of the energy storage module close to the input voltage of the main power tube or the synchronous freewheeling tube, so as to reduce the voltage difference between the drain of the main power tube and the source of the main power tube, and to reduce the voltage difference between the drain of the synchronous freewheeling tube and the source of the synchronous freewheeling tube, thereby suppressing the voltage stress spikes of the main power tube and the synchronous freewheeling tube during switching, thereby protecting the main power tube and the synchronous freewheeling tube from breakdown, and making the switching circuit more stable and safe.

[0059] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. For those skilled in the art, the technical solutions described in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents; and all these modifications and replacements should fall within the protection scope of the claims attached to the present invention.

Claims

1. A power tube peak absorption circuit, characterized in that: include: MOS tube, energy storage module, current limiting module and backflow prevention module, the input end of the energy storage module is connected to the drain of the power tube, the output end of the energy storage module is connected to the drain of the MOS tube, the source of the MOS tube is connected to one end of the current limiting module, the other end of the current limiting module is connected to the positive electrode of the backflow prevention module, the negative electrode of the backflow prevention module is connected to the source of the power tube, and the gate of the MOS tube and the gate of the power tube are both connected to an external controller.

2. The power tube peak absorption circuit according to claim 1, characterized in that: The current limiting module is a current limiting resistor.

3. The power tube peak absorption circuit according to claim 1, characterized in that: The anti-backflow module is an anti-backflow diode.

4. The power tube peak absorption circuit according to claim 1, characterized in that: The energy storage module is a capacitor.

5. A switching circuit, characterized in that: include: A controller, an input source, a main power tube, an inductor and an output source, wherein the drain of the main power tube is connected to the output source, the source of the main power tube is connected to the input end of the inductor, the output end of the inductor is connected to the output source, and the gate of the main power tube is connected to the controller, wherein a main power tube peak absorption circuit is provided on the main power tube, and the main power tube peak absorption circuit is the power tube peak absorption circuit as described in any one of claims 1-4.

6. The switch circuit according to claim 5, characterized in that: It also includes a synchronous freewheeling tube, the drain of which is connected between the source of the main power tube and the input end of the inductor, the source of which is grounded, and the gate of which is connected to the controller.

7. The switch circuit according to claim 6, characterized in that: The synchronous freewheeling tube is provided with a synchronous freewheeling tube peak absorption circuit, and the synchronous freewheeling tube peak absorption circuit is the same as the main power tube peak absorption circuit.

8. The switch circuit according to claim 5, characterized in that: It also includes a freewheeling diode, wherein the positive electrode of the freewheeling diode is connected to the output source, and the negative electrode of the freewheeling diode is grounded.

9. A charging control method for controlling the switch circuit according to any one of claims 5 to 8, characterized in that: The following steps are involved: Control the MOS tube in the main power tube peak absorption circuit to turn on, so as to charge the energy storage module in the main power tube peak absorption circuit; After charging is completed according to the RC charging time, the main power tube is controlled to turn on; And, controlling the MOS tube in the synchronous freewheeling tube peak absorption circuit to turn on, so as to charge the energy storage module in the synchronous freewheeling tube peak absorption circuit; After charging is completed according to the RC charging time, the synchronous freewheeling tube is controlled to turn on.

10. The charging control method according to claim 9, characterized in that: The energy storage module of the power tube peak absorption circuit is a capacitor, the current limiting module of the power tube peak absorption circuit is a current limiting resistor, and the calculation formula of the RC charging time is: t=RC×Ln(Vcc-V0) Wherein, t is the RC charging time, V0 is the initial voltage value of the capacitor, Vcc is the target voltage value of the capacitor charging, R is the resistance value of the current limiting resistor, and C is the capacitance value of the capacitor.

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