A voltage-sharing branch multiplexing type common-source common-gate high-voltage switch circuit and a control method thereof

Abstract

The application discloses a voltage-sharing branch multiplexing type common-source common-gate high-voltage switch circuit and a control method thereof, and particularly relates to the technical field of power electronic devices. The circuit comprises at least two parallel switch branches, a common voltage-sharing branch and a common driving unit branch. Each switch branch comprises n normally open semiconductor devices and n gate resistors. The common voltage-sharing branch comprises at least n dynamic voltage-sharing capacitors and n static voltage-sharing resistors. The common driving unit branch comprises n driving units. The dynamic voltage-sharing capacitors and the corresponding static voltage-sharing resistors are connected across two ends of the common voltage-sharing branch. The drains and sources of the normally open semiconductor devices in each switch branch are connected to the two ends of the common voltage-sharing branch, respectively. The n driving units synchronously provide driving for the devices in the corresponding levels of all the switch branches. The application solves the problem of low multiplexing rate of the voltage-sharing branch and the driving circuit of the existing common-source common-gate high-voltage switch when the switch is expanded in parallel.

Description

Technical Field

[0001] This invention relates to the field of power electronic device technology, and in particular to a common-source common-gate high-voltage switching circuit with voltage equalization branch multiplexing and its control method. Background Technology

[0002] As a key device for rapid DC fault clearing, DC solid-state switches are facing increasingly demanding voltage and current capacity requirements. Connecting multiple low-voltage semiconductor devices (such as MOSFETs and IGBTs) in series using a cascode structure can achieve medium- to high-voltage solid-state switches without significantly increasing process complexity. However, in terms of static voltage equalization, differences in parameters such as leakage current and threshold voltage among the devices lead to uneven voltage distribution during steady-state shutdown, potentially causing overvoltage breakdown in some devices. In terms of dynamic voltage equalization, differences in junction capacitance and drive signal transmission delay during switching transients result in extremely unbalanced voltage distribution, further exacerbating the breakdown risk. To meet greater current capacity requirements, multiple cascode switches are often directly connected in parallel. However, since the voltage equalization branches of each parallel branch are independent, the reuse rate is low, and coordination is impossible. Furthermore, due to differences in device transfer characteristics and loop parasitic parameters between parallel branches, complex current sharing control issues arise, requiring additional active or passive current sharing measures, further complicating circuit design and current sharing control strategies. Summary of the Invention

[0003] In view of the above problems, the present invention is proposed to provide a common source cascode high voltage switch circuit and its control method that overcomes or at least partially solves the above problems, thereby solving the problems of low reuse rate of the equalizing branch and the drive circuit and high complexity of branch current sharing control in existing common source cascode high voltage switches when they are connected in parallel for capacity expansion.

[0004] An embodiment of the present invention provides a common-source cascode high-voltage switching circuit with multiplexed voltage-equalizing branches, comprising: Several parallel switch branches, a common voltage equalization branch, and a common drive unit branch; Each switching branch includes n switching units; the common voltage equalization branch includes at least n dynamic voltage equalization capacitors, n static voltage equalization resistors, and n-1 diodes; the common drive unit branch includes n drive units. In each common voltage equalization branch, the first terminal of the first dynamic voltage equalization capacitor is connected to the first terminal of the first switching unit in each switching branch, and the second terminal of the first dynamic voltage equalization capacitor is connected to the input terminal of the second driving unit; the first terminal of the i-th dynamic voltage equalization capacitor is connected to the first terminal of the i-th static voltage equalization resistor, the second terminal of the i-th dynamic voltage equalization capacitor is connected to the second terminal of the i-th static voltage equalization resistor, the second terminal of the (i-1)-th voltage equalization capacitor is connected to the first terminal of the i-th dynamic voltage equalization capacitor; the first terminal of the n-th dynamic voltage equalization capacitor is connected to the input terminal of the n-th driving unit, and the second terminal of the n-th dynamic voltage equalization capacitor is connected to the second terminal of the n-th switching unit in each switching branch. The cathode of the first diode is connected to the input terminal of the second driving unit, and the anode of the first diode is connected to the input terminal of the first driving unit; the cathode of the (n-1)th diode is connected to the input terminal of the nth driving unit, and the anode of the (n-1)th diode is connected to the input terminal of the (n-1)th driving unit; the cathode of the kth diode is connected to the input terminal of the (k+1)th driving unit, and the anode of the kth diode is connected to the input terminal of the kth driving unit. The negative output terminal of the first driving unit is connected to the first terminal of the first switching unit in each switching branch, and the positive output terminal of the first driving unit is connected to the third terminal of the first switching unit in each switching branch; the negative output terminal of the i-th driving unit is connected to the first terminal of the i-th switching unit in each switching branch, and the positive output terminal of the i-th driving unit is connected to the third terminal of the i-th switching unit in each switching branch; where 1 < i ≤ n, 1 < k < n, n 2.

[0005] Furthermore, the switching unit includes a normally open semiconductor device and a gate resistor; the source of the normally open semiconductor device serves as the first terminal of the switching unit, the gate of the normally open semiconductor device serves as the second terminal of the switching unit, the drain of the normally open semiconductor device is connected to one end of the gate resistor, and the other end of the gate resistor serves as the third terminal of the switching unit.

[0006] Furthermore, the diode is an avalanche diode.

[0007] Furthermore, the driving unit includes an RC parallel branch, a voltage divider resistor, and a field-effect transistor; In each driving unit, the source of the field-effect transistor serves as the positive output terminal of the driving unit; one end of the voltage divider resistor is connected to the source of the field-effect transistor, and the other end of the voltage divider resistor is connected to the gate of the field-effect transistor; one end of the RC parallel branch is connected to the gate of the field-effect transistor, and the other end of the RC parallel branch serves as the negative output terminal of the i-th driving unit.

[0008] Furthermore, the field-effect transistors of the driving units are all N-channel depletion-type MOSFETs.

[0009] Furthermore, the switching unit also includes a clamping diode. In each switching unit, the cathode of the clamping diode is connected to the gate of the normally open semiconductor device, and the anode of the clamping diode is connected to the source of the normally open semiconductor device.

[0010] Furthermore, the normally open semiconductor devices in the switching branch are all IGBTs or MOSFETs.

[0011] Furthermore, when all normally open semiconductor devices in the switching branch are MOSFETs, the MOSFETs are N-channel enhancement-mode MOSFETs.

[0012] An embodiment of the present invention provides a control method for a common-source cascode high-voltage switch circuit with multiplexed voltage-equalizing branches, applied to the common-source cascode high-voltage switch circuit with multiplexed voltage-equalizing branches according to the first item of the present invention. The control method for the common-source cascode high-voltage switch circuit with multiplexed voltage-equalizing branches includes: A drive signal is injected between the input terminal and the negative output terminal of the first drive unit to turn on the voltage equalization branch multiplexed common source common gate high voltage switch circuit. The drive signal is a high level, which is greater than the on-state voltage drop of n-1 normally open semiconductor devices plus the on-state voltage drop of n-1 avalanche diodes in any switch branch.

[0013] Furthermore, it also includes: A disconnect signal is injected between the input terminal and the negative output terminal of the driving unit to disconnect the voltage equalization branch multiplexed common source common gate high voltage switch circuit; wherein, the disconnect signal is zero level or negative level; when the disconnect signal is negative level, the negative level is not lower than the minimum rated value of the gate-source voltage of any normally open semiconductor device.

[0014] The embodiments of the present invention have the following beneficial effects: This invention provides a common-source common-gate high-voltage switch circuit and its control method with a voltage-equalizing branch multiplexing feature. By setting at least two parallel switch branches and configuring a shared common voltage-equalizing branch and a common drive unit, dual reuse of the voltage-equalizing branch and drive unit is achieved. Multiple switch branches share the same voltage-equalizing branch, eliminating the need to configure dynamic voltage-equalizing capacitors and static voltage-equalizing resistors for each switch branch, effectively reducing the number of passive components used. Using the same voltage-equalizing branch ensures consistent voltage stress on semiconductor devices at the same level in each switch branch, achieving dynamic and static voltage equalization for devices in each switch branch. All switch branches share the same drive unit, and a single drive unit can simultaneously provide drive signals to semiconductor devices at the corresponding level in all switch branches, eliminating the need to set up independent drive circuits for each switch branch, simplifying the circuit scale on the drive side. Furthermore, the unified drive output ensures consistent drive voltage for devices at the same level in each branch, improving the synchronization of switching actions and the current sharing effect between branches. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a common-source common-gate high-voltage switch circuit with multiplexed voltage equalization branches provided in an embodiment of the present invention. The total number of switch branches is 2, and the normally open semiconductor devices of the two branches are MOSFETs, with 2 normally open semiconductor devices in each branch.

[0016] Figure 2 This is a schematic diagram of a common-source common-gate high-voltage switch circuit with multiplexed voltage equalization branches provided in an embodiment of the present invention. The total number of switch branches is 2, and the normally open semiconductor devices of the two branches are MOSFETs, with 4 normally open semiconductor devices in each branch.

[0017] Figure 3 This is a schematic diagram of a voltage equalization branch multiplexing type common source common gate high voltage switch circuit provided in an embodiment of the present invention. The total number of switch branches is 2, and the normally open semiconductor devices of the two switch branches are MOSFET and IGBT respectively, and the number of normally open semiconductor devices in each branch is 4.

[0018] Figure 4 This is a schematic diagram of a common-source common-gate high-voltage switch circuit with multiplexed voltage equalization branches provided in an embodiment of the present invention. The total number of switch branches is m+1, and the normally open semiconductor devices of the j-th branch are all MOSFETs or IGBTs, and the number of normally open semiconductor devices in each branch is n. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] This invention provides a common-source cascode high-voltage switching circuit with multiplexed voltage-equalizing branches, which may include at least: The system includes several parallel switch branches, a common voltage equalization branch, and a common drive unit branch. Each switch branch includes n switch units. The common voltage equalization branch includes at least n dynamic voltage equalization capacitors, n static voltage equalization resistors, and n-1 diodes. The common drive unit branch includes n drive units.

[0023] Each switching branch includes n switching units; the common voltage equalization branch includes at least n dynamic voltage equalization capacitors, n static voltage equalization resistors, and n-1 diodes; the common drive unit branch includes n drive units.

[0024] In each common voltage equalization branch, the first terminal of the first dynamic voltage equalization capacitor is connected to the first terminal of the first switching unit in each switching branch, and the second terminal of the first dynamic voltage equalization capacitor is connected to the input terminal of the second driving unit; the first terminal of the i-th dynamic voltage equalization capacitor is connected to the first terminal of the i-th static voltage equalization resistor, the second terminal of the i-th dynamic voltage equalization capacitor is connected to the second terminal of the i-th static voltage equalization resistor, the second terminal of the (i-1)-th voltage equalization capacitor is connected to the first terminal of the i-th dynamic voltage equalization capacitor; the first terminal of the n-th dynamic voltage equalization capacitor is connected to the input terminal of the n-th driving unit, and the second terminal of the n-th dynamic voltage equalization capacitor is connected to the second terminal of the n-th switching unit in each switching branch.

[0025] The cathode of the first diode is connected to the input terminal of the second driving unit, and the anode of the first diode is connected to the input terminal of the first driving unit; the cathode of the (n-1)th diode is connected to the input terminal of the nth driving unit, and the anode of the (n-1)th diode is connected to the input terminal of the (n-1)th driving unit; the cathode of the kth diode is connected to the input terminal of the (k+1)th driving unit, and the anode of the kth diode is connected to the input terminal of the kth driving unit.

[0026] The negative output terminal of the first driving unit is connected to the first terminal of the first switching unit in each switching branch, and the positive output terminal of the first driving unit is connected to the third terminal of the first switching unit in each switching branch; the negative output terminal of the i-th driving unit is connected to the first terminal of the i-th switching unit in each switching branch, and the positive output terminal of the i-th driving unit is connected to the third terminal of the i-th switching unit in each switching branch.

[0027] Each switching unit includes a normally open semiconductor device, a gate resistor, and a clamping diode; the source of the normally open semiconductor device serves as the first terminal of the switching unit, the drain of the normally open semiconductor device serves as the second terminal, the gate of the normally open semiconductor device is connected to one end of the gate resistor, and the other end of the gate resistor serves as the third terminal of the switching unit; the cathode of the clamping diode is connected to the gate of the normally open semiconductor device, and the anode of the clamping diode is connected to the source of the normally open semiconductor device.

[0028] Where 1 < i ≤ n, 1 < k < n, n 2.

[0029] In one embodiment of the present invention, when n=2 and there are two switch branches, the circuit structure of the present invention is as follows: Figure 1 As shown, it includes four normally open semiconductor devices (Q... 1a Q 2a Q 1b and Q 2b ), 4 clamping diodes, 4 gate resistors (R)g1a R g2a R g1b and R g2b ), one driver unit, one avalanche diode, and two static voltage divider resistors R 1a and R 1a and a dynamic voltage equalization capacitor C 1a and C 2a .

[0030] Each switching branch includes two normally open semiconductor devices and two gate resistors; The common voltage equalization branch includes two static voltage equalization resistors and two dynamic voltage equalization capacitors, used to provide drain-source voltage equalization protection for the normally open semiconductor devices in the two switching branches. The first terminal of the dynamic voltage equalization capacitor is connected to the first terminal of the static voltage equalization resistor, and the second terminal of the dynamic voltage equalization capacitor is also connected to the second terminal of the static voltage equalization resistor. The first terminal of the second dynamic voltage equalization capacitor is connected to the input terminal of the second driving unit. The input terminal of the second driving unit is connected to the cathode of the first avalanche diode. The anode of the first avalanche diode is connected to the input terminal of the first driving unit. The drain of the second normally open semiconductor device in each switching branch is connected to the second terminal of the second dynamic voltage equalization capacitor, and the source of the first normally open semiconductor device in each switching branch is connected to the first terminal of the first dynamic voltage equalization capacitor; the drain of the first normally open semiconductor device in each switching branch is connected to the source of the second normally open semiconductor device. The common drive unit branch includes two drive units, which are used to simultaneously provide synchronous gate drive signals to the semiconductor devices of the two switching branches, realizing the multiplexing of the drive units. The input terminal of the first drive unit is the drive signal input terminal. The positive output terminal of each drive unit is connected to one end of the corresponding gate resistor of each switching branch, and the other end of the gate resistor of each switching branch is connected to the gate of the corresponding normally open semiconductor device. The negative output terminal of the drive unit is connected to the source of the normally open semiconductor device of each switching branch.

[0031] Each drive unit includes an N-channel depletion-mode MOSFET, a voltage divider resistor, and an RC parallel branch, which is composed of a feedback capacitor and a voltage divider resistor connected in parallel. 1a and N 2a It is an N-channel depletion-type MOSFET, R N1a R N2a R Q1a and R Q2a For voltage divider resistors, C N1a and C N2aThis is the feedback capacitor. The drain of the N-channel depletion-type MOSFET serves as the input terminal of the drive unit, and the source of the N-channel depletion-type MOSFET serves as the positive output terminal of the drive unit. One end of the RC parallel branch is connected to the gate of the N-channel depletion-type MOSFET, and the other end serves as the negative output terminal of the drive unit. The voltage divider resistor R... N1a One end is connected to the source of the N-channel depletion-type MOSFET, and the other end is connected to the gate of the N-channel depletion-type MOSFET.

[0032] Please see Figure 2 In one embodiment of the present invention, n=4, and both switching branches use MOSFET devices. The circuit specifically includes two switching branches, three diodes, four normally open semiconductor devices, and multiple resistors, capacitors, and clamping diodes configured in a cascode configuration to form a high-voltage cascode structure. Wherein, Q... 1a To Q 4a Q 1b To Q 4b It is a normally open semiconductor device, shown as a MOSFET in the schematic diagram; R g1a To R g4a R g1b To R g4b N is the gate resistance. 1a To N 4a For field-effect transistors, D 1a To D 3a It is a diode, specifically an avalanche diode, R Q1a To R Q4a R N1a To R N4a C is the voltage divider resistor for the drive unit. N1a To C N4a For feedback capacitor, C 1a To C 4a For dynamic voltage equalization capacitors, R 1a To R 4a This is a static voltage equalization resistor. 1a To a 4a g 1a to g 4a g 1b to g 4b s 1a To s 4a s 1b To s 4b These represent the potentials corresponding to their respective locations.

[0033] Among them, D 1a To D 3a The diodes are, in order, the first avalanche diode, the second avalanche diode, and the third avalanche diode. C 1a To C 4aThe first to the fourth dynamic voltage equalization capacitors are listed in sequence, Q 1a To Q 4a The four normally open semiconductor devices are, in order, the first and the fourth normally open semiconductor devices.

[0034] Each switching branch includes four semiconductor devices, four gate resistors, and four clamping diodes. The common voltage-equalizing branch includes four dynamic voltage-equalizing capacitors, four static voltage-equalizing resistors, and three avalanche diodes. Each drive unit includes an RC parallel branch, voltage divider resistors, and field-effect transistors. The RC parallel branch consists of a feedback capacitor and a voltage divider resistor connected in parallel. All field-effect transistors are N-channel depletion-type MOSFETs. Q1a To R Q4a R N1a To R N4a These are the voltage divider resistors for the first to fourth driving units, in sequence.

[0035] The specific connection method is as follows: In each switching branch, the drain of the (i-1)th normally open semiconductor device is connected to the source of the ith normally open semiconductor device, and the gate resistor is connected to the gate of the ith normally open semiconductor device; the sources of the first normally open semiconductor devices in each switching branch are interconnected, and the drains of the nth normally open semiconductor devices are interconnected, as shown below. Figure 1 As shown in this embodiment, the drains of the fourth normally open semiconductor devices in the two switching branches are connected together; the cathode of the i-th clamping diode is connected to the gate of the i-th normally open semiconductor device, and the anode of the i-th clamping diode is connected to the source of the i-th normally open semiconductor device.

[0036] The first terminal of the first dynamic voltage equalizing capacitor is connected to the source of the first normally open semiconductor in each switching branch, and the second terminal of the first dynamic voltage equalizing capacitor is connected to the input terminal of the second driving unit.

[0037] The first terminal of the i-th dynamic voltage equalizing capacitor is connected to the first terminal of the i-th static voltage equalizing resistor, the second terminal of the i-th dynamic voltage equalizing capacitor is connected to the second terminal of the i-th static voltage equalizing resistor, and the second terminal of the (i-1)-th voltage equalizing capacitor is connected to the first terminal of the i-th dynamic voltage equalizing capacitor.

[0038] The first terminal of the nth dynamic voltage equalization capacitor is connected to the input terminal of the nth drive unit, and the second terminal of the nth dynamic voltage equalization capacitor is connected to the drain of the nth normally open semiconductor device in each switching branch. The cathode of the first avalanche diode is connected to the input terminal of the second driving unit, and the anode of the first avalanche diode is connected to the input terminal of the first driving unit. The cathode of the (n-1)th avalanche diode is connected to the input terminal of the nth driving unit, and the anode of the (n-1)th avalanche diode is connected to the input terminal of the (n-1)th driving unit. The cathode of the kth avalanche diode is connected to the input terminal of the (k+1)th driving unit, and the anode of the kth avalanche diode is connected to the input terminal of the kth driving unit. The negative output terminal of the first driving unit is connected to the source of the first normally open semiconductor device in each switching branch, and the positive output terminal of the first driving unit is connected to one end of the first gate resistor in each switching branch. The other end of the gate resistor is connected to the gate of the normally open semiconductor device corresponding to that branch.

[0039] The negative output terminal of the i-th driving unit is connected to the source of the i-th normally open semiconductor device of the first switching branch, and the positive output terminal of the i-th driving unit is connected to one end of the i-th gate resistor of each switching branch. The other end of the gate resistor is connected to the gate of the normally open semiconductor device corresponding to that branch.

[0040] In the i-th driving unit, the source of the i-th N-channel depletion-type MOSFET serves as the positive output terminal of the i-th driving unit; one end of the i-th voltage divider resistor is connected to the source of the i-th N-channel depletion-type MOSFET, and the other end of the i-th voltage divider resistor is connected to the gate of the i-th N-channel depletion-type MOSFET; one end of the i-th RC parallel branch is connected to the gate of the i-th N-channel depletion-type MOSFET, and the other end of the i-th RC parallel branch serves as the negative output terminal of the i-th driving unit. In the 1-th driving unit, the source of the 1-th field-effect transistor serves as the positive output terminal of the 1-th driving unit; one end of the 1-th voltage divider resistor is connected to the source of the 1-th field-effect transistor, and the other end of the 1-th voltage divider resistor is connected to the gate of the 1-th field-effect transistor; one end of the 1-th RC parallel branch is connected to the gate of the 1-th field-effect transistor, and the other end of the 1-th RC parallel branch serves as the negative output terminal of the i-th driving unit. Where i is a positive integer, 1 < i ≤ n, 1 < k < n, and i and k are the position parameters of the i-th and k-th normally open semiconductor devices, dynamic voltage equalizing capacitors, static voltage equalizing resistors, avalanche diodes and driving units, respectively. In this embodiment, any switch branch includes a total of 4 normally open semiconductor devices.

[0041] like Figure 2 As shown, the specific working principle of the circuit is as follows: When an external drive is needed to turn on the high-voltage switching circuit, a high-level drive signal is applied through the gate and source. The source connection of the first normally open semiconductor device in the two switching branches serves as the source of the high-voltage switching circuit, the drain connection of the fourth normally open semiconductor device in the two switching branches serves as the drain of the high-voltage switching circuit, and the anode of the first avalanche diode serves as the gate of the switching circuit. For Q... 1a Its conduction drive path passes through N sequentially. 1a Gate resistance R g1a Q 1a The gate and source of the high-voltage switching circuit; for Q 1b Its conduction drive path passes through N sequentially. 1a Gate resistance R g1b Q 1b The gate of the circuit and the source of the high-voltage switching circuit. That is, Q. 1a and Q 1b The drive circuit reuses N 1a Meanwhile, N 1a With voltage divider resistor R N1a R Q1a and feedback capacitor C N1a Together they constitute the basis of Q 1a and Q 1b Automatic closed-loop regulation circuit for gate voltage, and Q 1a and Q 1b Adjust the gate-source voltage to be consistent. Adjust Q... 1a Gate-source voltage at R N1a The partial voltage on and N 1a The gate voltage is compared to control the flow through N. 1a The current makes Q 1a The rate of rise of the gate-source voltage is controlled, thereby achieving closed-loop control of the gate-source voltage.

[0042] Similarly, the i-th N-channel enhancement-mode MOSFET Q in the two switching branches ia and Q ib Reuse the same drive unit, and N ia With the voltage divider resistor R in the same drive unit Nia R Qia and feedback capacitor C Nia Together, they form an automatic closed-loop gate voltage regulation circuit, adjusting the gate-source voltages of all devices in the same level (both i-level and 1-level) to be consistent. During the conduction transient, due to Q... ia and Q ib The gate is connected through the gate resistor R gia and R gibSince they are connected to the same drive output terminal and their potentials interact, when the gate potential of one MOSFET rises above that of the other, it charges the other gate potential, causing it to rise synchronously and ensuring gate voltage consistency. Based on the transfer characteristics of MOSFETs, automatic current sharing can be achieved among the switching branches at this time.

[0043] When the voltage equalization branch multiplexed common-source common-gate high-voltage switching circuit enters steady-state conduction, the internal control circuits of each drive unit reach electrical balance. Combining the saturation current characteristics of the depletion-type MOSFET at the drive end and the Kirchhoff voltage constraint condition of the voltage divider circuit, the steady-state calculation formula for the gate-source voltage of the i-th normally open semiconductor device can be derived: ; in This represents the steady-state value of the gate-source voltage of the i-th normally open semiconductor device. Let be the normal number of the N-channel depletion-type MOSFET in the i-th drive unit; The gate-source voltage turn-on threshold of the N-channel depletion-type MOSFET in the i-th driving unit; and Let be the voltage divider resistor for the i-th driving unit, where 1 ≤ i ≤ n.

[0044] Using the formula for calculating the steady-state gate-source voltage, the matching gate voltage can be obtained during the circuit design phase by iteratively calculating the inherent threshold parameters of the power device and the target steady-state gate voltage index. , The resistance value is determined to complete the pre-custom design of the drive unit; when different devices in the switching branch have inherent parameter discrepancies, the resistance parameters of the corresponding level drive unit can be finely adjusted to accurately correct the gate-source steady-state voltage of the single-stage device, so that all series devices can obtain a highly consistent conduction bias, realize the balanced distribution of static voltage in the series link, and avoid the uneven voltage division caused by parameter dispersion and the risk of overvoltage breakdown of a single device.

[0045] The steady-state distribution formula for the drain current of normally open semiconductor devices in the j-th switching branch is: ; in, Let be the branch current flowing through the j-th switch branch. Let m be the sum of the total currents in all switch branches, and m=1. .

[0046] When an external high-voltage switching circuit needs to be turned off, a low-level or zero-level turn-off signal is applied to the gate and source for Q. 1a Its turn-off drive path passes sequentially through the source and Q of the high-voltage switching circuit. 1a Gate, gate resistance Rg1a N 1a The body diode and the gate of the high-voltage switching circuit, wherein the body diode is a parasitic PN junction diode naturally present inside the MOSFET device; for Q 1b Its turn-off drive path passes sequentially through the source and Q of the high-voltage switching circuit. 1b gate, R g1b N 1a The body diode and the gate of the high-voltage switching circuit. For Q ia Its shutdown drive path passes through Q sequentially. (i-1)a drain, Q ia gate, R gia N ia Body diode, dynamic voltage equalization capacitor C 1a ~C (i-1)a and static equalizing resistor R 1a ~R (i-1)a For Q ib Its shutdown drive path passes through Q sequentially. (i-1)b drain, Q ib gate, R gib N ia Body diode, dynamic voltage equalization capacitor C 1a ~C (i-1)a and static equalizing resistor R 1a ~R (i-1)a .

[0047] During turn-off, both switching branches reuse the same set of dynamic voltage-equalizing capacitors and static voltage-equalizing resistors. When the capacitor and resistor parameters are matched, dynamic and static self-equalizing voltage can be achieved simultaneously for all devices. Meanwhile, for a single switching branch, if an abnormal rise in the gate voltage of a device causes a partial conduction tendency, the difference between the source potential of the device and the node potential of the voltage-equalizing capacitor at the corresponding level cannot change abruptly. This reverses the voltage drop, preventing the risk of false turn-on during turn-off, and ultimately the circuit stabilizes and enters a steady-state turn-off state.

[0048] Please see Figure 3 In one embodiment of the present invention, Figure 3 and Figure 2 The difference lies in the fact that the two switching branches use N-channel enhancement-mode MOSFETs and IGBT devices, respectively. Figure 3 Circuit structure and Figure 2 The circuit structures differ in that: Figure 3 In the middle circuit Q 1a To Q 4a For MOSFET, Q 1b To Q 4bThis refers to an IGBT. When n is 4, it comprises two normally open semiconductor devices in series, three avalanche diodes, four normally open semiconductor devices, and multiple resistors, capacitors, and clamping diodes configured in a cascode configuration to form a high-voltage cascode structure. Where Q... 1a To Q 4a Q 1b To Q 4b As a normally open semiconductor device, R g1a To R g4a R g1b To R g4b N is the gate resistance. 1a To N 4a It is an N-channel depletion-type MOSFET, D 1a To D 3a For avalanche diodes, R Q1a To R Q4a R N1a To R N4a C is the voltage divider resistor for the drive unit. N1a To C N4a For feedback capacitor, C 1a To C 4a For dynamic voltage equalization capacitors, R 1a To R 4a This is a static voltage equalization resistor. 1a To a 4a g 1a to g 4a g 1b to g 4b s 1a To s 4a s 1b To s 4b These represent the potentials corresponding to their respective locations. Where D... 1a To D 3a The diodes are, in order, the first avalanche diode, the second avalanche diode, and the third avalanche diode. C 1a To C 4a The first to the fourth dynamic voltage equalization capacitors are listed in sequence.

[0049] The specific connection method is as follows: In each switching branch, the drain of the (i-1)th normally open semiconductor device is connected to the source of the ith normally open semiconductor device, and the gate resistor is connected to the gate of the ith normally open semiconductor device; the sources of the first normally open semiconductor devices in each switching branch are interconnected, and the drains of the nth normally open semiconductor devices are interconnected, as shown below. Figure 3As shown in this embodiment, the drains of the fourth normally open semiconductor devices in the two switching branches are connected together; the cathode of the i-th clamping diode is connected to the gate of the i-th normally open semiconductor device, and the anode of the i-th clamping diode is connected to the source of the i-th normally open semiconductor device.

[0050] The first terminal of the first dynamic voltage equalizing capacitor is connected to the source of the first normally open semiconductor in each switching branch, and the second terminal of the first dynamic voltage equalizing capacitor is connected to the input terminal of the second driving unit.

[0051] The first terminal of the i-th dynamic voltage equalizing capacitor is connected to the first terminal of the i-th static voltage equalizing resistor, the second terminal of the i-th dynamic voltage equalizing capacitor is connected to the second terminal of the i-th static voltage equalizing resistor, and the second terminal of the (i-1)-th voltage equalizing capacitor is connected to the first terminal of the i-th dynamic voltage equalizing capacitor.

[0052] The first terminal of the nth dynamic voltage equalization capacitor is connected to the input terminal of the nth drive unit, and the second terminal of the nth dynamic voltage equalization capacitor is connected to the drain of the nth normally open semiconductor device in each switching branch. The cathode of the first avalanche diode is connected to the input terminal of the second driving unit, and the anode of the first avalanche diode is connected to the input terminal of the first driving unit. The cathode of the (n-1)th avalanche diode is connected to the input terminal of the nth driving unit, and the anode of the (n-1)th avalanche diode is connected to the input terminal of the (n-1)th driving unit. The cathode of the kth avalanche diode is connected to the input terminal of the (k+1)th driving unit, and the anode of the kth avalanche diode is connected to the input terminal of the kth driving unit. The negative output terminal of the first driving unit is connected to the source of the first normally open semiconductor device in each switching branch, and the positive output terminal of the first driving unit is connected to one end of the first gate resistor in each switching branch. The other end of the gate resistor is connected to the gate of the normally open semiconductor device corresponding to that branch.

[0053] The negative output terminal of the i-th driving unit is connected to the source of the i-th normally open semiconductor device of the first switching branch, and the positive output terminal of the i-th driving unit is connected to one end of the i-th gate resistor of each switching branch. The other end of the gate resistor is connected to the gate of the normally open semiconductor device corresponding to that branch.

[0054] In the i-th driving unit, the source of the i-th N-channel depletion-type MOSFET serves as the positive output terminal of the i-th driving unit; one end of the i-th voltage divider resistor is connected to the source of the i-th N-channel depletion-type MOSFET, and the other end of the i-th voltage divider resistor is connected to the gate of the i-th N-channel depletion-type MOSFET; one end of the i-th RC parallel branch is connected to the gate of the i-th N-channel depletion-type MOSFET, and the other end of the i-th RC parallel branch serves as the negative output terminal of the i-th driving unit. In the 1-th driving unit, the source of the 1-th field-effect transistor serves as the positive output terminal of the 1-th driving unit; one end of the 1-th voltage divider resistor is connected to the source of the 1-th field-effect transistor, and the other end of the 1-th voltage divider resistor is connected to the gate of the 1-th field-effect transistor; one end of the 1-th RC parallel branch is connected to the gate of the 1-th field-effect transistor, and the other end of the 1-th RC parallel branch serves as the negative output terminal of the i-th driving unit. Where 1 < i ≤ n, 1 < k < n.

[0055] like Figure 3 As shown, the specific working principle of the circuit is as follows: The voltage-equalizing branch multiplexing type common-source common-gate high-voltage switching circuit includes two switching branches. One switching branch uses only MOSFETs as normally open semiconductor devices, while the other uses only IGBTs. The two branches are configured with a common-source common-gate configuration, multiplexing the same set of voltage-equalizing branches and the same set of drive units to form a hybrid device type high-voltage switching architecture. When a conduction drive is applied to the high-voltage switching circuit, the high-level amplitude of the external drive signal is greater than the sum of the on-state voltage drops of n-1 normally open semiconductor devices and n-1 avalanche diodes in any one switching branch. The i-th drive unit, through its internal N-channel depletion-mode MOSFET, voltage divider resistor, and feedback capacitor forming an automatic closed-loop gate voltage regulation circuit, simultaneously drives the i-th MOSFET and IGBT in both switching branches, stabilizing their gate-source voltages to the same steady-state value. During the conduction transient process, the gates of the i-th MOSFET and IGBT in the two switching branches are connected to the output terminal of the same driving unit through their respective gate resistors. The gate potentials can be mutually restrained and rise synchronously through the driving circuit, ensuring the synchronicity of the switching actions of the two types of devices.

[0056] Once the circuit enters the steady-state conduction phase, ignoring the parameter variations of similar power devices, the on-resistance of each MOSFET can be considered consistent, and the on-resistance of each IGBT can be assumed to be consistent with its inherent on-state voltage drop. Let the steady-state conduction current flowing through the MOSFET series branch be... The steady-state conduction current flowing through the IGBT series branch is Since the two switching branches are connected in parallel, bear the same overall on-state voltage drop, and have consistent gate drive voltages under the closed-loop control of the drive unit, the on-state current of the two switching branches will be automatically allocated according to the current transfer characteristics of the MOSFET and IGBT respectively. The current ratio of a branch consisting entirely of MOSFETs to a branch consisting entirely of IGBTs satisfies: ; in, This refers to the current flowing through the MOSFET switching branches; The current flowing through branches consisting entirely of IGBTs in series is... The overall on-state voltage drop of the high-voltage switching circuit; and These are the on-resistances of a single MOSFET and IGBT, respectively; This is the inherent on-state voltage drop of a single IGBT. When hour, Depends on the on-state voltage drop of the MOSFET series branch; when hour, It depends on the on-state voltage drop of the IGBT series branch. Therefore It can be defined as: ; As deduced from the above conduction characteristics, MOSFETs and IGBTs each possess advantages in on-state voltage drop across different current ranges: MOSFETs have lower on-state voltage drops under low current conditions, while IGBTs have a more advantageous on-state voltage drop under high current conditions. This embodiment, through a hybrid MOSFET and IGBT branch configuration, can balance conduction performance at different current levels. Under operating conditions with a large total current flowing through the high-voltage switching circuit, the low on-state voltage drop characteristic of IGBTs at high currents can effectively reduce the overall on-state voltage drop of the circuit, thereby optimizing overall conduction losses.

[0057] Please see Figure 4 In one embodiment of the present invention, Figure 4 The circuit structure shown includes m+1 normally open semiconductor device series branches, and supports flexible combinations of x all-MOSFET series branches and y all-IGBT series branches, satisfying x+y=m+1 (x≥0, y≥0). All switching branches still share the same common voltage-equalizing branch and the corresponding level's common drive unit. Wherein, Q... 1a To Q na Q 1b To Q nb Q 1m To Q nm For normally open semiconductor devices, Q 1m To Qnm R is the first to the nth IGBT in a switching branch. g1a To R gna R g1b To R gnb R g1m To R gnm N is the gate resistor of the switching circuit. 1a To N na It is an N-channel depletion-type MOSFET, D 1a To D (n-1)a For avalanche diodes, R Q1a To R Qna、 R N1a To R Nna C is the voltage divider resistor for the drive unit. N1a To C Nna For feedback capacitor, C 1a To C na For dynamic voltage equalization capacitors, R 1a To R na This is a static voltage equalization resistor. 1a To a na g 1a to g na g 1b to g nb s 1a To s na s 1b To s nb These represent the potentials corresponding to their respective positions. In this embodiment, the normally open semiconductor devices in the j-th switch branch are all IGBTs or N-channel enhancement-mode MOSFETs, where 1 ≤ j ≤ m + 1; for example... Figure 4 As shown, Q 1a To Q na Q 1b To Q nb It is a MOSFET, specifically an N-channel enhancement-mode MOSFET, Q 1m To Q nm It is an IGBT.

[0058] The specific connection method is as follows: In each switching branch, the drain of the (i-1)th normally open semiconductor device is connected to the source of the ith normally open semiconductor device, and the ith gate resistor is connected to the gate of the ith normally open semiconductor device; the sources of the first normally open semiconductor devices in each switching branch are interconnected, and the drains of the nth normally open semiconductor devices are interconnected; the cathode of the ith clamping diode is connected to the gate of the ith normally open semiconductor device, and the anode of the ith clamping diode is connected to the source of the ith normally open semiconductor device.

[0059] The first terminal of the first dynamic voltage equalizing capacitor is connected to the source of the first normally open semiconductor in each switching branch, and the second terminal of the first dynamic voltage equalizing capacitor is connected to the input terminal of the second driving unit.

[0060] The first terminal of the i-th dynamic voltage equalizing capacitor is connected to the first terminal of the i-th static voltage equalizing resistor, the second terminal of the i-th dynamic voltage equalizing capacitor is connected to the second terminal of the i-th static voltage equalizing resistor, and the second terminal of the (i-1)-th voltage equalizing capacitor is connected to the first terminal of the i-th dynamic voltage equalizing capacitor.

[0061] The first terminal of the nth dynamic voltage equalization capacitor is connected to the input terminal of the nth drive unit, and the second terminal of the nth dynamic voltage equalization capacitor is connected to the drain of the nth normally open semiconductor device in each switching branch. The cathode of the first avalanche diode is connected to the input terminal of the second driving unit, and the anode of the first avalanche diode is connected to the input terminal of the first driving unit. The cathode of the (n-1)th avalanche diode is connected to the input terminal of the nth driving unit, and the anode of the (n-1)th avalanche diode is connected to the input terminal of the (n-1)th driving unit. The cathode of the kth avalanche diode is connected to the input terminal of the (k+1)th driving unit, and the anode of the kth avalanche diode is connected to the input terminal of the kth driving unit. The negative output terminal of the first driving unit is connected to the source of the first normally open semiconductor device in each switching branch, and the positive output terminal of the first driving unit is connected to one end of the first gate resistor in each switching branch. The other end of the gate resistor is connected to the gate of the normally open semiconductor device corresponding to that branch.

[0062] The negative output terminal of the i-th driving unit is connected to the source of the i-th normally open semiconductor device of the first switching branch, and the positive output terminal of the i-th driving unit is connected to one end of the i-th gate resistor of each switching branch. The other end of the gate resistor is connected to the gate of the normally open semiconductor device corresponding to that branch.

[0063] In the i-th driving unit, the source of the i-th N-channel depletion-type MOSFET serves as the positive output terminal of the i-th driving unit; one end of the i-th voltage divider resistor is connected to the source of the i-th N-channel depletion-type MOSFET, and the other end of the i-th voltage divider resistor is connected to the gate of the i-th N-channel depletion-type MOSFET; one end of the i-th RC parallel branch is connected to the gate of the i-th N-channel depletion-type MOSFET, and the other end of the i-th RC parallel branch serves as the negative output terminal of the i-th driving unit. In the 1-th driving unit, the source of the 1-th field-effect transistor serves as the positive output terminal of the 1-th driving unit; one end of the 1-th voltage divider resistor is connected to the source of the 1-th field-effect transistor, and the other end of the 1-th voltage divider resistor is connected to the gate of the 1-th field-effect transistor; one end of the 1-th RC parallel branch is connected to the gate of the 1-th field-effect transistor, and the other end of the 1-th RC parallel branch serves as the negative output terminal of the i-th driving unit. Where 1 < i ≤ n, 1 < k < n.

[0064] like Figure 4 As shown, the specific working principle of the circuit is as follows: When the number of switch branches increases to m+1, the working principle of the high-voltage switch circuit is the same as... Figure 3 Similarly, the m+1 switching branches achieve self-driving and dynamic / static self-equalizing of each normally open semiconductor device through multiplexing drive circuits and voltage equalizing branches. When analyzing the steady-state conduction characteristics of the multiplexed common-source common-gate high-voltage switching circuit in this embodiment, to simplify the theoretical derivation and clearly reveal the core working mechanism of the circuit, the parameter dispersion of each type of semiconductor device and passive component can be ignored. Since all power devices in the same switching branch are selected from the same model and production batch and grouped according to key parameters, and all static voltage equalizing resistors in the shared voltage equalizing branch are high-precision passive components with the same nominal resistance value, it can be considered that: The on-resistance of each MOSFET satisfies: ; The on-resistance of each IGBT satisfies: The inherent on-state voltage drop of each IGBT satisfies ; The resistance values ​​of each static voltage equalizing resistor satisfy the following: Based on the above parameter consistency assumption, the steady-state on-current flowing through each MOSFET switching branch is of the same magnitude and is denoted as . The steady-state conduction current flowing through each IGBT switching branch is of the same magnitude and is denoted as . The current flowing through each MOSFET switching branch is different from the current flowing through each IGBT switching branch. Furthermore, under closed-loop control of the drive circuit to achieve the same gate voltage, the current will be automatically allocated based on the transfer characteristics of the MOSFET and IGBT. The ratio is calculated using the following formula: ; in, The overall on-state voltage drop of the high-voltage switching circuit; The on-resistance of a single MOSFET; The on-resistance of a single IGBT; This is the inherent on-state voltage drop of a single IGBT. When hour, It depends on the on-state voltage drop of each MOSFET switching branch; when hour, It depends on the on-state voltage drop of each IGBT switching branch. Therefore Defined as: ; As can be seen from the above formulas, the high-voltage switching circuit composed of MOSFETs and IGBTs exhibits different on-state voltage drops under different currents. Considering that the on-state voltage drop of IGBTs at high currents will be less than that of MOSFETs, an IGBT series branch can be added to reduce the overall on-state voltage drop of the high-voltage switching circuit, thereby optimizing conduction losses.

[0065] The total conduction loss of the high-voltage switching circuit in this embodiment includes two parts: the power semiconductor branch loss and the common static voltage equalization branch loss. The total conduction loss of the high-voltage switching circuit is defined by the following formula: ; in, Let be the total conduction loss of the cascode high-voltage switching circuit with multiplexed voltage-equalizing branches after expanding the number of switching branches to m+1, where x is the total number of MOSFET switching branches and y is the total number of IGBT switching branches. , Let x be the on-resistance losses of all MOSFET switching branches. Let y be the on-resistance loss of each IGBT branch. The losses are due to the inherent on-state voltage drop of the IGBT. To address the static power consumption generated by the shared static equalizing resistor branch, in practical applications, the ratio of x to y can be adjusted to flexibly adapt to the loss optimization requirements under different load current conditions.

[0066] One embodiment of the present invention provides a control method for a common-source cascode high-voltage switch circuit with multiplexed voltage-equalizing branches, applicable to any embodiment of the present invention. The method includes: A drive signal is injected between the input and negative output terminals of the first drive unit, i.e., between the gate and source of the voltage-equalizing branch multiplexed cascode high-voltage switch circuit, to turn on the circuit. The drive signal is high-level, and its amplitude is greater than the sum of the on-state voltage drops of the n-1 avalanche diodes and the normally open semiconductor devices in any of the n-1 arbitrary switch branches. This ensures that each normally open semiconductor device receives sufficient gate bias and achieves full conduction, avoiding increased conduction losses due to insufficient drive. After the circuit enters steady-state conduction, each switch branch can automatically achieve current sharing according to the drive closed loop. For circuits using a hybrid MOSFET and IGBI branch configuration, different numbers of these two types of switch branches can be matched to adapt to the low on-state voltage drop requirements under different current conditions, optimizing the overall conduction loss and operating efficiency of the circuit.

[0067] A disconnect signal is injected between the input and negative output terminals of the drive unit, i.e., between the gate and source terminals of the high-voltage switching circuit, to disconnect the voltage equalization branch multiplexed common-source common-gate high-voltage switching circuit. The disconnect signal is either zero or negative. When the disconnect signal is negative, the negative level is not lower than the minimum rated gate-source voltage of any normally open semiconductor device, preventing damage from negative overvoltage at the device's gate and source. During the turn-off process, each parallel branch uses the voltage equalization branch to achieve dynamic and static voltage equalization, ensuring voltage stress balance at each stage of the device, while suppressing the risk of false turn-on during turn-off transients, and improving the stability and reliability of the switch turn-off process.

[0068] This invention employs a shared voltage-equalizing branch design under a common-source, common-gate architecture, allowing multiple switching branches to reuse the same voltage-equalizing branch consisting of a dynamic voltage-equalizing capacitor, a static voltage-equalizing resistor, and an avalanche diode. This eliminates the need for separate voltage-equalizing components for each switching branch, reducing the number of passive components. Furthermore, the current-carrying capacity can be flexibly adjusted by increasing or decreasing the number of switching branches, achieving modular expansion of current capacity. Through the reuse of same-level drive units, a single N... The driving unit, consisting of a channel depletion-mode MOSFET, two resistors, and one capacitor, provides a stable and consistent gate bias for all switching branches at the same level using only one set of driving components. This reduces the number of driving-side components while ensuring the synchronization of switching actions of devices in each switching branch, enhancing the overall driving capability of the circuit. Each switching branch can achieve automatic current sharing based on the unified gate driving conditions and the inherent transfer characteristics of the devices. Branches with the same type of devices can naturally share the steady-state current, and hybrid MOSFET and IGBT branches can autonomously complete current distribution according to their respective conduction characteristics, eliminating the need for additional active current sharing sampling circuits and control algorithms, thus reducing system control complexity. At the same time, the circuit supports flexible configuration of the ratio of branches consisting entirely of MOSFETs to branches consisting entirely of IGBTs. By utilizing the advantages of the on-state voltage drop of the two types of devices in different current ranges, it can adapt to the operating requirements of multiple operating conditions. In high-current operating scenarios, the overall on-state voltage drop can be reduced by increasing the number of IGBT switching branches, effectively optimizing the total conduction loss of the circuit and improving operating efficiency.

[0069] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0070] Those skilled in the art will clearly understand that, for convenience and simplicity, the specific working process of the device described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0071] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A common-source, common-grid high-voltage switching circuit with multiplexed voltage-equalizing branches, characterized in that, include: Several parallel switch branches, a common voltage equalization branch, and a common drive unit branch; Each switch branch includes n switch units; The common voltage equalization branch includes: at least n dynamic voltage equalization capacitors, n static voltage equalization resistors, and n-1 diodes; the common drive unit branch includes n drive units; In each common voltage equalization branch, the first terminal of the first dynamic voltage equalization capacitor is connected to the first terminal of the first switching unit in each switching branch, and the second terminal of the first dynamic voltage equalization capacitor is connected to the input terminal of the second driving unit; the first terminal of the i-th dynamic voltage equalization capacitor is connected to the first terminal of the i-th static voltage equalization resistor, the second terminal of the i-th dynamic voltage equalization capacitor is connected to the second terminal of the i-th static voltage equalization resistor, the second terminal of the (i-1)-th voltage equalization capacitor is connected to the first terminal of the i-th dynamic voltage equalization capacitor; the first terminal of the n-th dynamic voltage equalization capacitor is connected to the input terminal of the n-th driving unit, and the second terminal of the n-th dynamic voltage equalization capacitor is connected to the second terminal of the n-th switching unit in each switching branch. The cathode of the first diode is connected to the input terminal of the second driving unit, and the anode of the first diode is connected to the input terminal of the first driving unit; the cathode of the (n-1)th diode is connected to the input terminal of the nth driving unit, and the anode of the (n-1)th diode is connected to the input terminal of the (n-1)th driving unit; the cathode of the kth diode is connected to the input terminal of the (k+1)th driving unit, and the anode of the kth diode is connected to the input terminal of the kth driving unit. The negative output terminal of the first driving unit is connected to the first terminal of the first switching unit in each switching branch, and the positive output terminal of the first driving unit is connected to the third terminal of the first switching unit in each switching branch; the negative output terminal of the i-th driving unit is connected to the first terminal of the i-th switching unit in each switching branch, and the positive output terminal of the i-th driving unit is connected to the third terminal of the i-th switching unit in each switching branch; where 1 < i ≤ n, 1 < k < n, n 2.

2. The voltage equalization branch multiplexing type common source common grid high voltage switching circuit as described in claim 1, characterized in that, The switching unit includes a normally open semiconductor device and a gate resistor; the source of the normally open semiconductor device serves as the first terminal of the switching unit, the drain of the normally open semiconductor device serves as the second terminal of the switching unit, the gate of the normally open semiconductor device is connected to one end of the gate resistor, and the other end of the gate resistor serves as the third terminal of the switching unit.

3. The voltage equalization branch multiplexing type common source common grid high voltage switching circuit as described in claim 1, characterized in that, The diode is an avalanche diode.

4. The voltage equalization branch multiplexing type common source common grid high voltage switching circuit as described in claim 1, characterized in that, The drive unit includes an RC parallel branch, a voltage divider resistor, and a field-effect transistor; In each driving unit, the source of the field-effect transistor serves as the positive output terminal of the driving unit; one end of the voltage divider resistor is connected to the source of the field-effect transistor, and the other end of the voltage divider resistor is connected to the gate of the field-effect transistor; one end of the RC parallel branch is connected to the gate of the field-effect transistor, and the other end of the RC parallel branch serves as the negative output terminal of the i-th driving unit.

5. The voltage equalization branch multiplexing type common source common grid high voltage switching circuit as described in claim 4, characterized in that, The field-effect transistors of the driving units are all N-channel depletion-type MOSFETs.

6. The voltage equalization branch multiplexing type common source common grid high-voltage switching circuit as described in claim 2, characterized in that, The switching unit further includes a clamping diode. In each switching unit, the cathode of the clamping diode is connected to the gate of the normally open semiconductor device, and the anode of the clamping diode is connected to the source of the normally open semiconductor device.

7. The voltage equalization branch multiplexing type common source common grid high voltage switching circuit as described in claim 1, characterized in that, The normally open semiconductor devices in the switching branches are all IGBTs or MOSFETs.

8. The voltage equalization branch multiplexing type common source common grid high voltage switching circuit as described in claim 7, characterized in that, When all normally open semiconductor devices in the switching branch are MOSFETs, the MOSFETs are N-channel enhancement-mode MOSFETs.

9. A control method for a common-source, common-grid high-voltage switch circuit with multiplexed voltage-equalizing branches, characterized in that, Applied to the voltage equalization branch multiplexing type common source common grid high voltage switching circuit as described in claim 1; The control method for the voltage equalization branch multiplexing type common source common grid high voltage switch circuit includes: A drive signal is injected between the input terminal and the negative output terminal of the first drive unit to turn on the voltage equalization branch multiplexed common source common gate high voltage switch circuit. The drive signal is a high level, which is greater than the on-state voltage drop of n-1 normally open semiconductor devices plus the on-state voltage drop of n-1 avalanche diodes in any switch branch.

10. The control method for a common-source, common-grid high-voltage switch circuit with multiplexed voltage-equalizing branches as described in claim 9, characterized in that, Also includes: A disconnect signal is injected between the input terminal and the negative output terminal of the driving unit to disconnect the voltage equalization branch multiplexed common source common gate high voltage switch circuit; wherein, the disconnect signal is zero level or negative level; when the disconnect signal is negative level, the negative level is not lower than the minimum rated value of the gate-source voltage of any normally open semiconductor device.

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