Current sharing circuit based on parallel MOSFETs

Abstract

The invention discloses a current sharing circuit based on parallel MOSFETs, the current sharing circuit comprises a reference branch, a to-be-adjusted branch and a current sharing module, the current sharing module comprises a first current sharing circuit and a second current sharing circuit, and when the voltage VLn of the first connecting end of an inductor Ln of the to-be-adjusted branch is larger than the voltage VLJ of the first connecting end of a reference inductor LJ, the first current sharing circuit is connected with the second current sharing circuit. The first current sharing circuit introduces part of grid current of the branch switch tube Qn to be adjusted into a first connecting end of the reference inductor LJ; when the voltage VLn of the first connecting end of the to-be-adjusted branch inductor Ln is smaller than the voltage VLJ of the first connecting end of the reference inductor LJ, the second current sharing circuit introduces part of grid current of the reference branch switch tube QJ into the first connecting end of the to-be-adjusted branch inductor Ln, and therefore current sharing between the reference branch and the to-be-adjusted branch is achieved. The current sharing circuit is simple in structure, quick in response, capable of achieving spontaneous current sharing without an additional power supply, beneficial to integration and capable of achieving effective current sharing on large-current and high-frequency occasions.

Description

Technical Field

[0001] The present invention belongs to the technical field of switching power supplies, and relates to a current sharing circuit based on parallel MOSFETs, which is applicable to dynamic current sharing of parallel switching tubes under high current conditions. Background Art

[0002] The switching tube parallel current sharing technology is an important technology in the modern power electronics field, and is widely used in systems such as high-efficiency power converters, inverters, and electric vehicles. With the rapid increase in power demand, a single switching tube may experience problems such as overheating, reduced efficiency, and decreased reliability when handling high currents. Therefore, using multiple switching tubes in parallel has become an effective solution. However, it is difficult to keep the line parameters between each parallel branch and the stray parameters between the parallel switching tubes completely consistent, resulting in uneven output currents in each branch, which in turn increases the current stress on the switching tubes, increases the switching loss, and even leads to thermal runaway. Therefore, an effective current sharing control strategy is needed to ensure that the current amplitude distribution of each parallel branch is as balanced as possible.

[0003] Currently, the existing research on the method of dynamic current sharing of switching tubes usually includes inductive coupling, layout optimization, and gate drive. The method of inductive coupling for parallel branches usually uses the differential-mode inductor to suppress the differential-mode current for current sharing. However, this method often introduces inductors with large volumes, which is not suitable for the case of multiple parallel branches. At the same time, the excessive inductor will cause a large voltage overshoot, increasing the breakdown risk of the device.

[0004] The method of optimizing the layout on the PCB or DBC suppresses the parasitic parameters that are inconsistent between parallel branches by changing the trace length of the parallel branches. However, the difficulty of layout optimization will increase significantly when this method is applied to the case of multiple parallel branches. At the same time, when the circuit environment changes, it is often necessary to redesign the layout optimization circuit, which does not have a certain universality.

[0005] Gate driving of switching tubes usually requires collecting the current signals of parallel branches and inputting them into the control unit for signal processing. Then, the control unit outputs signals to drive the gate of the switching tubes to achieve current sharing. The essence of this method is to adjust the gate current of the switching tubes, thereby changing the turn-on or turn-off speed of the switching tubes and the current change slope. However, the existing methods currently have complex control circuits and high costs, which are not conducive to integration. Summary of the Invention

[0006] The present invention aims to solve the problem of dynamic imbalance of current during the parallel current sharing process of switching tubes, so that it can be applied to occasions with high power, large current and high power density. To solve this problem, the present invention provides a current sharing circuit based on parallel MOSFETs, which can achieve current balance in a spontaneous form while ensuring the effectiveness and expandability of the current sharing circuit, without the need for an additional power supply, thereby reducing its complexity and additional losses.

[0007] The above object of the present invention is achieved by the following technical means: A current sharing circuit based on parallel MOSFETs includes a reference branch, an adjustable branch and a current sharing module. The reference branch includes a reference branch switching tube Q J and a reference inductor L J . The source of the reference branch switching tube Q J is connected to the first connection end of the reference inductor L J . The second connection end of the reference inductor L J is connected to electrical ground. The adjustable branch includes an adjustable branch switching tube Q n and an adjustable branch inductor L n . The source of the adjustable branch switching tube Q n is connected to the first connection end of the adjustable branch inductor L n . The second connection end of the adjustable branch inductor L n is connected to electrical ground. The current sharing module includes a first current sharing circuit and a second current sharing circuit. When the voltage V n at the first connection end of the adjustable branch inductor L Ln is greater than the voltage V J at the first connection end of the reference inductor L LJ , the first current sharing circuit introduces a part of the gate current of the adjustable branch switching tube Q n into the first connection end of the reference inductor L J ; When the voltage V n at the first connection end of the adjustable branch inductor L Ln is less than the voltage V J at the first connection end of the reference inductor L LJ , the second current sharing circuit introduces a part of the gate current of the reference branch switching tube Q J into the first connection end of the adjustable branch inductor L n .

[0008] The first current sharing circuit includes a first diode D1, a first switching tube Q1 and a first current limiting resistor R1; the anode of the first diode D1 is connected to the adjustable branch switching tube Q nis connected to the gate, the cathode of the first diode D1 is connected to the drain of the first switching transistor Q1, and the gate of the first switching transistor Q1 is respectively connected to the source of the switching transistor Q of the branch to be adjusted n and the first connection end of the inductor L of the branch to be adjusted n is connected, the source of the first switching transistor Q1 is connected to one end of the first current limiting resistor R1, and the other end of the first current limiting resistor R1 is respectively connected to the source of the switching transistor Q of the reference branch J and the first connection end of the reference inductor L J is connected.

[0009] The first switching transistor Q1 is an enhancement-mode NMOS. When the voltage V n at the first connection end of the inductor L Ln of the branch to be adjusted minus the voltage V J at the first connection end of the reference inductor L LJ has a difference greater than the threshold voltage V th1 of the first switching transistor Q1, the drain and source of the first switching transistor Q1 are turned on.

[0010] The second current sharing circuit includes a second diode D2, a second switching transistor Q2, and a second current limiting resistor R2; the cathode of the second diode D2 is connected to the gate of the switching transistor Q of the branch to be adjusted n The anode of the second diode D2 is connected to the drain of the second switching transistor Q2, and the gate of the second switching transistor Q2 is respectively connected to the source of the switching transistor Q of the branch to be adjusted n The source of which is connected to the first connection end of the inductor L of the branch to be adjusted n The source of the second switching transistor Q2 is connected to one end of the second current limiting resistor R2, and the other end of the second current limiting resistor R2 is respectively connected to the source of the switching transistor Q of the reference branch J and the first connection end of the reference inductor L J is connected.

[0011] The second switching transistor Q2 is an enhancement-mode PMOS. When the voltage V J at the first connection end of the reference inductor L LJ minus the voltage V n at the first connection end of the inductor L Ln of the branch to be adjusted has a difference greater than the threshold voltage V th2 of the second switching transistor Q2, the drain and source of the second switching transistor Q2 are turned on.

[0012] The branch to be adjusted is multiple paths, and each path to be adjusted corresponds to a current sharing module.

[0013] It further includes an input power supply V in and a storage inductor L Z , the positive pole of the input power supply V in is connected to the storage inductor L Zis connected to the first connection end, and the input power supply V in The negative electrode of is connected to the electrical ground, and the energy storage inductor L Z A reference branch and an adjustable branch are connected in parallel between the second connection end of and the electrical ground.

[0014] It also includes a rectifier diode D Z , an energy storage capacitor C Z and a load R Z ; The anode of the rectifier diode D Z is connected to the second connection end of the energy storage inductor L Z , one end of the energy storage capacitor C Z and one end of the load R Z are both connected to the cathode of the rectifier diode D Z , the other end of the energy storage capacitor C Z and the other end of the load R Z are both connected to the electrical ground.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses a controllable device to detect the change rate of the current in the parallel branches, selects the reference branch and the adjustable branch, and controls the magnitude of the gate current of the MOSFET in the adjustable branch through the current sharing module, adjusts the on and off speeds of the switching tubes in the adjustable branch, and makes them tend to be consistent with the switching speed of the switching tubes in the reference branch, so as to effectively suppress the dynamic unbalanced current of the overall parallel branches and achieve dynamic current sharing within a certain range. The current sharing circuit of the present invention has a simple structure, rapid response, can perform current sharing spontaneously and does not require an additional power supply, which is beneficial to integration and can achieve effective current sharing in high-current and high-frequency occasions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the structural diagram of the current sharing module of the present invention; Figure 2 is the schematic diagram of the connection mode of the present invention with a two-way parallel boost boost circuit; Figure 3 is the expansion diagram of the connection mode of the present invention with a multi-way parallel boost boost circuit; Figure 4 is the current waveform of the switching tube of the adjustable branch in parallel and the switching tube of the reference branch before adding the current sharing module in Embodiment 1 of the present invention; Figure 5 is the current waveform of the switching tube of the adjustable branch in parallel and the switching tube of the reference branch after adding the current sharing module in Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] For the convenience of those of ordinary skill in the art to understand and implement the present invention, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0018] For the convenience of subsequent description and analysis, the definitions of parameters such as the voltage and current of circuit elements are as follows: I J is the current on the reference branch, I n is the current on the nth branch to be adjusted, I3 is the current sharing current flowing out from the gate of the switching tube of the branch to be adjusted in the current sharing module, and I4 is the current sharing current flowing into the gate of the switching tube of the branch to be adjusted in the current sharing module. V LJ is the reference inductance L of the reference branch J The voltage on it is also the source voltage of the switching tube Q J (NMOS) of the reference branch, V Ln is the inductance L of the branch to be adjusted of the nth branch to be adjusted n The voltage on it is also the source voltage of the switching tube Q n (NMOS) of the nth branch to be adjusted, V th1 is the threshold voltage of the first switching tube Q1 (NMOS), V th2 is the threshold voltage of the second switching tube Q2 (PMOS).

[0019] Embodiment 1

[0020] As Figure 1 shown, a current sharing circuit based on parallel MOSFETs includes a current sharing module. The current sharing module includes a first diode D1, a second diode D2, a first switching tube Q1, a second switching tube Q2, a first current limiting resistor R1, and a second current limiting resistor R2. The first switching tube Q1 is an enhancement-type NMOS, and the second switching tube Q2 is an enhancement-type PMOS.

[0021] The cathode of the first diode D1 is connected to the drain of the first switching tube Q1. The anode of the first diode D1 is connected to the cathode of the second diode D2. The source of the first switching tube Q1 is connected to one end of the first current limiting resistor R1. The anode of the second diode D2 is connected to the drain of the second switching tube Q2. The source of the second switching tube Q2 is connected to one end of the second current limiting resistor R2. The other end of the second current limiting resistor R2 is connected to the other end of the first current limiting resistor R1. The gate of the first switching tube Q1 is connected to the gate of the second switching tube Q2. The current sharing module of the present invention has three external interfaces, namely a, b, and c. Interface a is connected to the gate of the first switching tube Q1, the gate of the second switching tube Q2, and at the same time to the source of the switching tube Q n of the external parallel branch to be adjusted and the inductance L of the branch to be adjustedn The first connection terminals are all connected to detect the current change rate of the branch to be adjusted. Interface b is connected to the connection point between the first current-limiting resistor R1 and the second current-limiting resistor R2, and is also connected to the source electrode of the reference branch switch Q J and the first connection terminal of the reference inductor L J to detect the current change rate of the reference branch. Interface c is connected to the anode of the first diode D1, the cathode of the second diode D2, and is also connected to the gate of the branch switch Q to be adjusted n gate connection.

[0022] To illustrate the feasibility of the current sharing module, the current sharing module is used in a boost boost circuit, such as Figure 2 shown, and also includes an input power supply V in , energy storage inductor L Z , rectifier diode D Z , energy storage capacitor C Z , load R Z , reference branch switch Q J , reference inductor L J , branch switch Q to be adjusted n , inductor L of the branch to be adjusted n . n is the nth branch to be adjusted. In this embodiment, n = 1.

[0023] The positive pole of the input power supply V in is connected to the first connection terminal of the energy storage inductor L Z , and the second connection terminal of the energy storage inductor L Z is connected to the anode of the rectifier diode D Z . One end of the energy storage capacitor C Z , one end of the load R Z are both connected to the cathode of the rectifier diode D Z . The other end of the energy storage capacitor C Z , the other end of the load R Z , and the negative pole of the input power supply V in are all connected to the electrical ground. A parallel reference branch and a branch to be adjusted are connected between the anode of the rectifier diode D Z and the electrical ground; The reference branch includes a reference branch switch Q J , reference inductor L J . The drain of the reference branch switch Q J is connected to the anode of the rectifier diode D Z and the second connection terminal of the energy storage inductor L Z . The source of the reference branch switch Q J is connected to the first connection terminal of the reference inductor L J , and the reference inductor L JThe second connection terminal is connected to electrical ground; The branch to be adjusted includes the switch transistor Q of the branch to be adjusted n , the inductor L of the branch to be adjusted n , the switch transistor Q of the branch to be adjusted n The drain of which is connected to the anode of the rectifier diode D Z and the second connection terminal of the energy storage inductor L Z are both connected. The source of the switch transistor Q of the branch to be adjusted n is connected to the first connection terminal of the inductor L of the branch to be adjusted n , and the second connection terminal of the inductor L of the branch to be adjusted n is connected to electrical ground; The current sharing module interface a is connected to the source of the switch transistor Q of the branch to be adjusted n and the first connection terminal of the inductor L of the branch to be adjusted n are both connected. The current sharing module interface b is connected to the source of the reference branch switch transistor Q J and the first connection terminal of the reference inductor L J are both connected. The current sharing module interface c is connected to the gate of the switch transistor Q of the branch to be adjusted n .

[0024] When the currents I J , I n of the parallel branches are unbalanced, unbalanced voltages V J and V n will be reflected on the reference inductor L of the reference branch LJ and the inductor L of the branch to be adjusted Ln , V LJ is the voltage of the reference inductor L J . When the first switch transistor Q1 and the second switch transistor Q2 are not conducting, the source voltages of the first switch transistor Q1 and the second switch transistor Q2 are both equal to V LJ , V Ln is the voltage of the first connection terminal of the inductor L of the branch to be adjusted n . The gate voltage V g1 of the first switch transistor Q1 and the gate voltage V g2 of the second switch transistor Q2 are both equal to V Ln .

[0025] When V Ln is greater than V LJ , since the second switch transistor Q2 is an enhancement-type PMOS, its source voltage is equal to V L1 , and the gate voltage V Ln of the second switch transistor Q2 is greater than its source voltage V LJ , the second switch transistor Q2 is not conducting (device characteristics of enhancement-type PMOS); When V LJ and VLn The absolute value of the difference is less than the threshold voltage V of the first switching transistor Q1 th1 When the absolute value of the difference is reached, the source voltage of the first switching transistor Q1 is equal to V LJ , since the first switching transistor Q1 is an enhancement-type NMOS, the first switching transistor Q1 is not turned on, and both the first switching transistor Q1 and the second switching transistor Q2 operate in the off state, and the current sharing module does not work.

[0026] When V Ln is greater than V LJ , and the absolute value of the difference between V LJ and V Ln is greater than the absolute value of the threshold voltage V th1 of the first switching transistor Q1, the first switching transistor Q1 is turned on, the second switching transistor Q2 is turned off, and at the same time, a first current sharing current I3 flows out from the gate of the switching transistor Q n of the branch to be adjusted, passes through the first diode D1, the first switching transistor Q1 and the first current limiting resistor R1, and flows into the reference inductor L of the reference branch J . At this time, since the gate current of the switching transistor Q n of the branch to be adjusted decreases, its switching speed becomes slower, thereby reducing the current I n of the branch to be adjusted and tending to be equal to I n and I J , and further achieving the effect of reducing the unbalanced current.

[0027] When the first switching transistor Q1 is turned on, V Ln =V LJ +V th1 +V R1 , V R1 is the voltage across the first current limiting resistor R1 when the first switching transistor Q1 is turned on, and the absolute value of the difference between V LJ and V Ln always remains greater than the absolute value of the threshold voltage V th1 of the first switching transistor Q1, and the first switching transistor Q1 will not be affected by the generated current sharing current and change its conduction state.

[0028] When V LJ is greater than V Ln , since the first switching transistor Q1 is an enhancement-type NMOS, its gate voltage is equal to V Ln , and the gate voltage V Ln of the first switching transistor Q1 is less than its source voltage V LJ , so the first switching transistor Q1 is not turned on (device characteristics of enhancement-type NMOS); when the absolute value of the difference between V LJ and V Ln is less than the absolute value of the threshold voltage V th2 of the second switching transistor Q2, the source voltage of the second switching transistor Q2 is equal to VLJ When the first switching transistor Q1 and the second switching transistor Q2 are both in the off state, the current sharing module does not operate. When V LJ is greater than V Ln , and the absolute value of the difference between the two is greater than the absolute value of the threshold voltage V th2 of the second switching transistor Q2, the switching transistor Q2 turns on, the switching transistor Q1 turns off, and at the same time, a second current sharing current I4 flows out from the source of the reference branch switching transistor Q J , passes through the second current limiting resistor R2, the second switching transistor Q2, and the second diode D2, and flows into the gate of the switching transistor Q n of the branch to be adjusted. At this time, since the gate current of the switching transistor Q n of the branch to be adjusted increases, its switching speed becomes faster, thereby increasing the current I n of the branch to be adjusted, tending to be equal to I n and I J , and further achieving the effect of reducing the unbalanced current.

[0029] When the second switching transistor Q2 is turned on, V LJ = V Ln + V th2 + V R2 , V R2 is the voltage across the first current limiting resistor R2 when the second switching transistor Q2 is turned on. When the absolute value of the difference between V LJ and V Ln always remains greater than the absolute value of the threshold voltage V th2 of the second switching transistor Q2, the second switching transistor Q2 will not affect its conduction state due to the generation of the current sharing current.

[0030] Embodiment 2

[0031] Based on the above principle, when the number of branches to be adjusted increases, the effect of current sharing of multiple parallel switching transistors can still be achieved by increasing the number of current sharing modules. As Figure 3 shown, when the number of branches to be adjusted is n, the current sharing module of the present invention is connected between each reference branch and the branch to be adjusted, and the connection method of the current sharing module is the same as that in Embodiment 1.

[0032] Embodiment 3

[0033] In order to verify the accuracy of Embodiment 1, Embodiment 1 is tested. The voltage of the input power supply V in is 50V, the energy storage inductor L Z is 20uH, the energy storage capacitor C Z is 80uF, the load resistor R Z is 80Ω, the switching frequency is 50kHz, the reference inductor L J and the inductor L nBoth are 50 nH. To simulate the inconsistency of the stray parameters of the switching transistors and the differences in the circuit parameters, in the first embodiment, the on-resistance R-DS(ON J ) of the switching transistor Q (QJ) in the reference branch is set to 0.032 Ω, the threshold voltage V th3 is set to 1.67 V, and the driving resistance Rg （QJ） is set to 15.3 Ω; the on-resistance R-DS(ON n ) of the switching transistor Q (Qn) in the branch to be adjusted is set to 0.034 Ω, its threshold voltage V th4 is set to 1.7 V, and the driving resistance Rg （Qn） is set to 15 Ω. Under this condition, observe the changes in the currents of the reference branch and the branch to be adjusted before and after adding the current sharing module of the present invention.

[0034] Select to observe the current waveforms of the reference branch and the branch to be adjusted at the running time of 8.168 ms. It can be seen from Figure 4 that when the current sharing module of the present invention is not added, the unbalanced current between the reference branch and the branch to be adjusted is relatively large. Define the current unbalance degree between the reference branch and the branch to be adjusted at the same moment as : (1) where is the current on the reference branch, is the current on the branch to be adjusted, and abs is the absolute value operation. According to formula (1), the maximum current unbalance degree can be calculated as 34.82%.

[0035] It can be seen from Figure 5 that after adding the current sharing module of the present invention, the maximum unbalanced current between the reference branch and the branch to be adjusted is significantly reduced. According to formula (1), the maximum current unbalance degree after adding the current sharing module can be calculated as 21.12%.

[0036] By comparing the current waveforms of the reference branch and the branch to be adjusted before and after adding the current sharing module of the present invention, and by calculating the average value and the effective value of the current within the turn-on time of the switching transistors in the reference branch and the branch to be adjusted, it can be known that before adding the current sharing module of the present invention, the average current unbalance degree is 9.37%, and the effective current unbalance degree is 10.22%; after adding the current sharing module of the present invention, the average current unbalance degree is 7.36%, and the effective current unbalance degree is 8.78%. Both are improved to a certain extent compared with before adding the current sharing module of the present invention.

[0037] Through the above analysis, it can be concluded that the current sharing module of the present invention can balance the unbalanced current during the dynamic process of the parallel switching transistors by adjusting the magnitude of the gate current of the switching transistor Q in the branch to be adjusted. n Thereby effectively balancing the unbalanced current during the dynamic process of the parallel switching transistors.

[0038] The above-disclosed are only the preferred embodiments of the present invention, but the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims and several improvements made without departing from the principle of the present invention should all fall within the protection scope of the present invention.

Claims

1. A current sharing circuit based on parallel MOSFETs, including a reference branch, characterized in that, It further includes a branch to be adjusted and a current sharing module. The reference branch includes a reference branch switching transistor Q J and a reference inductor L J . The source of the reference branch switching transistor Q J is connected to the first connection end of the reference inductor L J . The second connection end of the reference inductor L J is connected to electrical ground. The branch to be adjusted includes the switch tube Q of the branch to be adjusted n and the inductor L of the branch to be adjusted n , the source electrode of the switch tube Q of the branch to be adjusted n is connected to the first connection end of the inductor L of the branch to be adjusted n , the second connection end of the inductor L of the branch to be adjusted n is connected to the electrical ground The current sharing module includes a first current sharing circuit and a second current sharing circuit. When the voltage V n at the first connection end of the to-be-adjusted branch inductor L Ln is greater than the voltage V J at the first connection end of the reference inductor L LJ , the first current sharing circuit introduces a part of the gate current of the switch Q n in the to-be-adjusted branch into the first connection end of the reference inductor L J ; When the voltage V n at the first connection end of the to-be-adjusted branch inductor L Ln is less than the voltage V J at the first connection end of the reference inductor L LJ , the second current sharing circuit introduces a part of the gate current of the reference branch switching transistor Q J to the first connection end of the to-be-adjusted branch inductor L n .

2. The current sharing circuit based on parallel MOSFETs according to claim 1, characterized in that, The first current sharing circuit includes a first diode D1, a first switching transistor Q1, and a first current limiting resistor R1; the anode of the first diode D1 is connected to the gate of the switching transistor Q of the branch to be adjusted n ; the cathode of the first diode D1 is connected to the drain of the first switching transistor Q1, and the gate of the first switching transistor Q1 is respectively connected to the source of the switching transistor Q of the branch to be adjusted n and the first connection end of the inductor L of the branch to be adjusted n ; the source of the first switching transistor Q1 is connected to one end of the first current limiting resistor R1, and the other end of the first current limiting resistor R1 is respectively connected to the source of the switching transistor Q of the reference branch J and the first connection end of the reference inductor L J .

3. The current sharing circuit based on parallel MOSFETs according to claim 2, characterized in that, The first switch tube Q1 is an enhanced NMOS. When the branch inductance L n The voltage V at the first connection terminal Ln Subtract the reference inductance L J The first connection terminal voltage V LJ The difference is greater than the threshold voltage V th1 When , the drain and source of the first switch tube Q1 are connected.

4. The current sharing circuit based on parallel MOSFETs according to claim 1, characterized in that, The second current sharing circuit includes a second diode D2, a second switching transistor Q2, and a second current limiting resistor R2; the cathode of the second diode D2 is connected to the gate of the switching transistor Q of the branch to be adjusted n ; the anode of the second diode D2 is connected to the drain of the second switching transistor Q2, and the gate of the second switching transistor Q2 is respectively connected to the source of the switching transistor Q of the branch to be adjusted n and the first connection end of the inductor L of the branch to be adjusted n ; the source of the second switching transistor Q2 is connected to one end of the second current limiting resistor R2, and the other end of the second current limiting resistor R2 is respectively connected to the source of the switching transistor Q of the reference branch J and the first connection end of the reference inductor L J .

5. The current sharing circuit based on parallel MOSFETs according to claim 4, characterized in that, The second switching transistor Q2 is an enhancement-mode PMOS. When the voltage V J at the first connection terminal of the reference inductor L LJ minus the voltage V n at the first connection terminal of the branch inductor L to be adjusted Ln is greater than the threshold voltage V th2 of the second switching transistor Q2, the drain and source of the second switching transistor Q2 are turned on.

6. The current sharing circuit based on parallel MOSFETs according to claim 1, characterized in that, There are multiple branches to be adjusted, and each branch to be adjusted corresponds to a current sharing module.

7. The current sharing circuit based on parallel MOSFETs according to claim 1, characterized in that, It also includes an input power supply V in and a storage inductor L Z , the positive electrode of the input power supply V in is connected to the first connection end of the storage inductor L Z , the negative electrode of the input power supply V in is connected to the electrical ground, and a reference branch and a branch to be adjusted are connected in parallel between the second connection end of the storage inductor L Z and the electrical ground.

8. The current sharing circuit based on parallel MOSFETs according to claim 7, characterized in that, It also includes a rectifier diode D Z , an energy storage capacitor C Z and a load R Z ; the anode of the rectifier diode D Z is connected to the second connection end of the energy storage inductor L Z ; one end of the energy storage capacitor C Z and one end of the load R Z are both connected to the cathode of the rectifier diode D Z ; the other end of the energy storage capacitor C Z and the other end of the load R Z are both connected to electrical ground.

Images