Self-triggering square wave pulse generator based on capacitive coupling energy harvesting

Abstract

The application discloses a self-triggering square wave pulse generator based on capacitive coupling energy extraction, which comprises a power supply unit, a current-limiting protection resistor, a pulse forming main circuit and a driving circuit; the power supply unit supplies power for the pulse forming main circuit through the current-limiting protection resistor; the driving circuit adjusts the on-off of the switch tube of the pulse forming main circuit, so that the pulse forming main circuit outputs pulses; the application can provide a discharge loop with a smaller time constant for gate-source charge, improve the off-delay time of each stage of the Marx circuit; meanwhile, the application can also provide a charging loop with a smaller time constant for the equivalent output capacitor of the main switch, shorten the output trailing edge of each stage of the Marx circuit.

Description

Technical Field

[0001] The present invention relates to the field of pulse generators, in particular to a self-triggered square wave pulse generator based on capacitive coupling energy extraction. Background Art

[0002] Solid-state Marx pulse generators have been widely used in fields such as biomedicine, plasma processing, and food processing. In Marx circuits, the stepwise increase in potential during pulse discharge necessitates reliable switch isolation and drive. Typically, this requires isolated transmission of control signals and isolated power supply for signal power amplification. A common approach employs a power converter based on magnetic coupling isolation in conjunction with signal isolation (such as fiber optic converters, optocoupler chips, and magnetic coupling chips). However, the use of magnetic coupling elements (magnetic cores and coils) and signal isolation measures increases the size and cost of the device. An improved approach integrates a magnetic core-coupled gate drive circuit, which can simultaneously transmit control signals and drive energy to the switch for direct switch actuation, eliminating the need for signal isolation and significantly reducing costs. However, this approach's operating frequency is limited by the core's limited low frequency, and the conditioning circuitry on the core's secondary side increases system complexity.

[0003] Unlike the magnetic coupling method that uses coil coupling, capacitive coupling technology uses capacitor voltage division to obtain energy, which has more advantages in terms of system volume, cost and complexity. Among them, the self-triggered Marx circuit topology based on capacitive coupling technology can complete the switching control of all Marx levels through an external control signal without taking any isolation measures, which greatly reduces the system volume and complexity. However, during the switch-off phase, the charge stored in the capacitors at both ends of the gate and source will be discharged through the load, and the charging of the equivalent output capacitor of the switch also passes through the load resistance. The large time constant causes the switch to turn off slowly and gradually increases the turn-off delay, which will cause the output pulse to tail. This phenomenon is particularly significant under high-impedance load conditions.

[0004] In summary, the main methods currently used for switch isolation and drive in Marx circuits are magnetic coupling isolation technology and capacitive coupling technology. Although capacitive coupling technology has a simple structure and is easy to operate and control, it suffers from problems such as delayed switch-off and pulse tailing under high-resistance loads. Its square wave pulse output capability is limited, further restricting the application prospects of self-triggered Marx. Summary of the Invention

[0005] The purpose of the present invention is to provide a self-triggered square wave pulse generator based on capacitive coupling energy extraction, including a power supply unit, a current limiting protection resistor, a pulse shaping main circuit, and a drive circuit;

[0006] The power supply unit supplies power to the pulse shaping main circuit through a current limiting protection resistor;

[0007] The driving circuit adjusts the on / off of the switch tube of the pulse shaping main circuit so that the pulse shaping main circuit outputs pulses externally;

[0008] The pulse shaping main circuit includes n-stage pulse generating circuits connected in series, each stage of the pulse generating circuit includes an isolation diode D i , energy storage capacitor C i 、N-MOSFET S ni and P-MOSFET S pi ; Among them, N-MOSFET and P-MOSFET serve as the main switch and shaping switch of the pulse shaping main circuit; i=1,2,…,n;

[0009] The driving circuit includes a first-level external signal driving control unit and an n-1-level pulse driving unit;

[0010] The pulse driving unit includes an energy-taking capacitor and an energy-dissipating resistor.

[0011] Furthermore, the external signal driving control unit receives the external control signal and transmits it to the first-stage pulse generating circuit, so that the N-MOSFET S of the first-stage pulse generating circuit is turned on. n1 and P-MOSFET S p1 Driven by external control signal;

[0012] Each pulse driving unit is connected to other driving pulse generating circuits except the first stage, so that the j-th driving pulse generating circuit is driven in sequence by capacitor coupling; j=2, 3, ... n.

[0013] Furthermore, the energy dissipation resistor is used to continuously consume gate-source charge during the pulse output stage, thereby generating unbalanced charge and reversing the gate-source voltage polarity during charge redistribution at the trailing edge of the pulse, thereby meeting the negative voltage drive requirements of the P-MOSFET.

[0014] Furthermore, the self-triggering square wave pulse generator outputs a pulse voltage of -nU0; U0 is the output voltage of the power supply unit.

[0015] Furthermore, the charging voltage range of the self-triggering square wave pulse generator is 0-600V, and the pulse width range is 200ns-1000ns.

[0016] Furthermore, the circuit topology of the pulse drive unit is as follows:

[0017] Diode D i Series capacitor C i Back-connected P-MOSFET S pi ;

[0018] Diode D i Connect N-MOSFET S ni ;

[0019] N-MOSFET S ni and P-MOSFET S pi Cascode connection.

[0020] Furthermore, in the pulse drive unit, the energy-taking capacitor C Pj Connected across the source of the switch of the previous stage (j-1) and the gate of the switch of the current stage (j); j = 2, 3, ..., n;

[0021] Energy dissipation resistor and N-MOSFET S ni connect.

[0022] Furthermore, the equivalent input capacitance C issj N-MOSFET S ni and P-MOSFET S pi The sum of equivalent input capacitance;

[0023] Furthermore, the operating modes of the self-triggered square wave pulse generator include a charging mode, a pulse discharge mode, a drive energy dissipation mode, a pulse cutoff mode, and a recovery mode.

[0024] Furthermore, when the self-triggered square wave pulse generator is in charging mode, the N-MOSFETS n1 Turn off, P-MOSFETS p1 The remaining switches in the pulse shaping main circuit are in the off state, and the energy storage capacitor C i Through the body diode of the previous (i-2) P-MOSFET and the first-stage switch S p1 Charge to U0; U0 is the output voltage of the power supply unit;

[0025] When the self-triggered square wave pulse generator is in pulse discharge mode, the N-MOSFETS n1 On, P-MOSFETS p1 Shutdown, C pj -C issj Branch C i Charging; when C issj The voltage across both ends reaches the N-MOSFET turn-on threshold voltage V gsnth When the N-MOSFETS of the j-th pulse generating circuit nj On, P-MOSFETS pj Turn off, repeat this process until the main switches of the pulse generating circuits at all levels are turned on, and a -nU0 pulse voltage output is generated on the load; j = i + 1;

[0026] When the self-triggered square wave pulse generator is in the driving energy dissipation mode, the equivalent input capacitance of each stage of the pulse generating circuit releases energy to the parallel energy dissipation resistor, and the energy dissipation resistor continuously consumes the gate-source charge during the pulse output stage;

[0027] When the self-triggered square wave pulse generator is in pulse cutoff mode, under the control of external signal, the P-MOSFETS p1 On, N-MOSFETS n1 Shutdown, C iss2 with C p2 Parallel, C issj is reversely charged to the P-MOSFET turn-on threshold voltage V gspth , N-MOSFETS of the j-th pulse generation circuit nj Immediately turn off, P-MOSFETS p1 Repeat this process until the main switches of the pulse generating circuits at all levels are all turned off and the shaping switches are all turned on;

[0028] When the self-triggered square wave pulse generator is in recovery mode, C iss with C p The parallel connection will pass through the parallel resistor R gs and the current limiting resistor releases the charge until C iss with C p When the voltage returns to zero potential, each switch returns to the working state of charging mode.

[0029] The technical effect of the present invention is unquestionable. The present invention proposes to introduce a common source and common gate structure composed of an N-channel metal oxide semiconductor field effect transistor (N-MOSFET) and a P-channel metal oxide semiconductor field effect transistor (P-MOSFET) into a Marx circuit, so as to realize the complementary conduction state of the main switch and the shaping switch when working under single drive control.

[0030] The present invention proposes a negative voltage driving technology based on capacitive coupling energy extraction. By adding a discharge resistor, an unbalanced charge is generated in the pulse flat-top stage, and then the gate-source voltage polarity is reversed at the trailing edge of the pulse to drive the P-MOSFET to turn on.

[0031] The present invention introduces a common source and common gate structure component, and the Marx circuit has a pulse trailing edge shaping capability under the driving of a single capacitive coupling signal.

[0032] In the present invention, a gate-source resistor is connected in parallel, so that the P-MOSFET can obtain sufficient negative voltage drive at the trailing edge of the pulse.

[0033] The present invention can provide a discharge circuit with a smaller time constant for the gate-source charge, thereby improving

[0034] The Marx circuit reduces the turn-off delay at each stage; it also provides a charging loop with a smaller time constant for the equivalent output capacitance of the main switch, shortening the output trailing edge of each stage of the Marx circuit. Compared with existing topologies, this circuit can significantly shorten the tail of the pulse output overall. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the overall structure of the pulse generator;

[0036] Figure 2 is the circuit topology;

[0037] Figure 3 The circuit topology of the self-triggered square wave pulse generator in different working modes; Figure 3 (a) is charging mode; Figure 3 (b) is the pulse discharge mode; Figure 3 (c) is the driving energy dissipation mode; Figure 3 (d) is the pulse discharge mode; Figure 3 (e) is recovery mode;

[0038] Figure 4 (a) is a simplified equivalent circuit; Figure 4 (b) is the self-triggered gate voltage;

[0039] Figure 5 It is a prototype of an 8-level self-triggered square wave pulse generator;

[0040] Figure 6 (a) is the output voltage waveform of each level (pulse width 500ns); Figure 6 (b) is the load voltage waveform (pulse width 300-600ns). DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to the following examples, but it should not be understood that the scope of the present invention is limited to the following examples. Without departing from the above technical ideas of the present invention, various substitutions and modifications can be made according to common technical knowledge and customary means in the art, and all should be included in the scope of protection of the present invention.

[0042] Example 1:

[0043] See also Figures 1 to 6 , a self-triggered square wave pulse generator based on capacitor coupling energy extraction, including a power supply unit, a current limiting protection resistor, a pulse shaping main circuit, and a driving circuit;

[0044] The power supply unit supplies power to the pulse shaping main circuit through a current limiting protection resistor;

[0045] The driving circuit adjusts the on / off of the switch tube of the pulse shaping main circuit so that the pulse shaping main circuit outputs pulses externally;

[0046] The pulse shaping main circuit includes n-stage pulse generating circuits connected in series, each stage of the pulse generating circuit includes an isolation diode D i , energy storage capacitor C i 、N-MOSFET S ni and P-MOSFET S pi ; Among them, N-MOSFET and P-MOSFET serve as the main switch and shaping switch of the pulse shaping main circuit; i=1,2,…,n;

[0047] The driving circuit includes a first-level external signal driving control unit and an n-1-level pulse driving unit;

[0048] The pulse driving unit includes an energy-taking capacitor and an energy-dissipating resistor.

[0049] The external signal driving control unit receives the external control signal and transmits it to the first-stage pulse generating circuit, so that the N-MOSFET S n1 and P-MOSFET S p1 Driven by external control signal;

[0050] Each pulse driving unit is connected to other driving pulse generating circuits except the first stage, so that the j-th driving pulse generating circuit is driven in sequence by capacitor coupling; j=2, 3, ... n.

[0051] The energy dissipation resistor is used to continuously consume the gate-source charge during the pulse output stage, thereby generating unbalanced charge and reversing the gate-source voltage polarity during charge redistribution at the trailing edge of the pulse, thereby meeting the negative voltage drive requirements of the P-MOSFET.

[0052] The output pulse voltage of the self-triggering square wave pulse generator is -nU0; U0 is the output voltage of the power supply unit.

[0053] The charging voltage range of the self-triggering square wave pulse generator is 0-600V, and the pulse width range is 200ns-1000ns.

[0054] The circuit topology of the pulse drive unit is as follows:

[0055] Diode D i Series capacitor C i Back-connected P-MOSFET S pi ;

[0056] Diode D i Connect N-MOSFET S ni ;

[0057] N-MOSFET S ni and P-MOSFET S piCascode connection.

[0058] In the pulse drive unit, the energy-taking capacitor C pj Connected across the source of the switch of the previous stage (j-1) and the gate of the switch of the current stage (j); j = 2, 3, ..., n;

[0059] The equivalent input capacitance Cissj is the sum of the equivalent input capacitances of N-MOSFET Sni and P-MOSFET Spi; the energy dissipation resistor is the sum of the equivalent input capacitances of N-MOSFET Sni and P-MOSFET Spi. ni connect.

[0060] The working modes of the self-triggered square wave pulse generator include charging mode, pulse discharge mode, drive energy dissipation mode, pulse cutoff mode, and recovery mode.

[0061] When the self-triggered square wave pulse generator is in charging mode, the N-MOSFETS n1 Turn off, P-MOSFETS p1 The remaining switches in the pulse shaping main circuit are in the off state, and the energy storage capacitor C i After the first (i-2) P-MOSFET body diode and S p1 Charge to U0; U0 is the output voltage of the power supply unit;

[0062] When the self-triggered square wave pulse generator is in pulse discharge mode, the N-MOSFETS n1 On, P-MOSFETS p1 Shutdown, C pj -C issj Branch C i Charging; when C issj The voltage across both ends reaches the N-MOSFET turn-on threshold voltage V gsnth When the N-MOSFETS of the j-th pulse generating circuit nj On, P-MOSFETS pj Turn off, repeat this process until the main switches of the pulse generating circuits at all levels are turned on, and a -nU0 pulse voltage output is generated on the load; j = i + 1;

[0063] When the self-triggered square wave pulse generator is in the driving energy dissipation mode, the equivalent input capacitance of each stage of the pulse generating circuit releases energy to the parallel energy dissipation resistor, and the energy dissipation resistor continuously consumes the gate-source charge during the pulse output stage;

[0064] When the self-triggered square wave pulse generator is in pulse cutoff mode, under the control of external signal, the P-MOSFETS p1 On, N-MOSFETS n1 Shutdown, C iss2 with C p2 Parallel, Cissj is reversely charged to the P-MOSFET turn-on threshold voltage V gspth , N-MOSFETS of the j-th pulse generation circuit nj Immediately turn off, P-MOSFETS p1 Repeat this process until the main switches of the pulse generating circuits at all levels are all turned off and the shaping switches are all turned on;

[0065] When the self-triggered square wave pulse generator is in recovery mode, C iss with C p The parallel connection will pass through the parallel resistor R gs and the current limiting resistor releases the charge until C iss with C p When the voltage returns to zero potential, each switch returns to the working state of charging mode.

[0066] Example 2:

[0067] A self-triggered square wave pulse generator based on capacitive coupling energy extraction includes a power supply unit, a current limiting protection resistor, a pulse shaping main circuit, and a drive circuit;

[0068] The power supply unit supplies power to the pulse shaping main circuit through a current limiting protection resistor;

[0069] The driving circuit adjusts the on / off of the switch tube of the pulse shaping main circuit so that the pulse shaping main circuit outputs pulses externally;

[0070] The pulse shaping main circuit includes n-stage pulse generating circuits connected in series, each stage of the pulse generating circuit includes an isolation diode D i , energy storage capacitor C i 、N-MOSFET S ni and P-MOSFET S pi ; Among them, N-MOSFET and P-MOSFET serve as the main switch and shaping switch of the pulse shaping main circuit; i=1,2,…,n;

[0071] The driving circuit includes a first-level external signal driving control unit and an n-1-level pulse driving unit;

[0072] The pulse driving unit includes an energy-taking capacitor and an energy-dissipating resistor.

[0073] Example 3:

[0074] The self-triggered square wave pulse generator based on capacitor coupling energy extraction has the same technical content as embodiment 2. Furthermore, the external signal driving control unit receives the external control signal and transmits it to the first-stage pulse generating circuit, so that the N-MOSFET S of the first-stage pulse generating circuit n1 and P-MOSFET Sp1 Driven by external control signal;

[0075] Each pulse driving unit is connected to other driving pulse generating circuits except the first stage, so that the j-th driving pulse generating circuit is driven in sequence by capacitor coupling; j=2, 3, ... n.

[0076] Example 4:

[0077] A self-triggered square wave pulse generator based on capacitive coupling energy extraction has the same technical content as any one of Examples 2-3. Furthermore, the energy dissipation resistor is used to continuously consume the gate-source charge during the pulse output stage, thereby generating unbalanced charge, and reversing the gate-source voltage polarity when the charge is redistributed at the trailing edge of the pulse, thereby meeting the negative voltage drive requirements of the P-MOSFET.

[0078] Example 5:

[0079] The self-triggering square wave pulse generator based on capacitor coupling energy extraction has the same technical content as any one of Examples 2-4. Furthermore, the output pulse voltage of the self-triggering square wave pulse generator is -nU0; U0 is the output voltage of the power supply unit.

[0080] Example 6:

[0081] A self-triggered square wave pulse generator based on capacitive coupling energy extraction has the same technical content as any one of Examples 2-5. Furthermore, the charging voltage range of the self-triggered square wave pulse generator is 0-600V, and the pulse width range is 200ns-1000ns.

[0082] Example 7:

[0083] The self-triggered square wave pulse generator based on capacitive coupling energy extraction has the same technical content as any one of Examples 2-6. Furthermore, the circuit topology of the pulse driving unit is as follows:

[0084] Diode D i Series capacitor C i Back-connected P-MOSFET S pi ;

[0085] Diode D i Connect N-MOSFET S ni ;

[0086] N-MOSFET S ni and P-MOSFET S pi Cascode connection.

[0087] Example 8:

[0088] The self-triggered square wave pulse generator based on capacitor coupling energy extraction has the same technical content as any one of embodiments 2-7. Furthermore, in the pulse driving unit, the energy extraction capacitor C pj Connected across the source of the switch of the previous stage (j-1) and the gate of the switch of the current stage (j), j = 2, 3, ..., n;

[0089] Energy dissipation resistor and N-MOSFET S ni connect.

[0090] Example 9:

[0091] The self-triggered square wave pulse generator based on capacitor coupling energy extraction has the same technical content as any one of embodiments 2-8. Furthermore, the equivalent input capacitance C issj N-MOSFET S ni and P-MOSFET S pi The sum of equivalent input capacitance;

[0092] Example 10:

[0093] The self-triggered square wave pulse generator based on capacitive coupling energy extraction has the same technical content as any one of Examples 2-9. Furthermore, the working modes of the self-triggered square wave pulse generator include charging mode, pulse discharge mode, drive energy discharge mode, pulse cutoff mode, and recovery mode.

[0094] Example 11:

[0095] The self-triggered square wave pulse generator based on capacitor coupling energy extraction has the same technical content as any one of embodiments 2-10. Furthermore, when the self-triggered square wave pulse generator is in charging mode, the N-MOSFETS n1 Turn off, P-MOSFETS p1 The remaining switches in the pulse shaping main circuit are in the off state, and the energy storage capacitor C i Through the body diode of the first (i-2) P-MOSFET and the first-stage switch S p1 Charge to U0; U0 is the output voltage of the power supply unit;

[0096] When the self-triggered square wave pulse generator is in pulse discharge mode, the N-MOSFETS n1 On, P-MOSFETS p1 Shutdown, C pj -C issj Branch C i Charging; when C issj The voltage across both ends reaches the N-MOSFET turn-on threshold voltage V gsnth When the N-MOSFETS of the j-th pulse generating circuit nj On, P-MOSFETS pjTurn off, repeat this process until the main switches of the pulse generating circuits at all levels are turned on, and a -nU0 pulse voltage output is generated on the load; j = i + 1;

[0097] When the self-triggered square wave pulse generator is in the driving energy dissipation mode, the equivalent input capacitance of each stage of the pulse generating circuit releases energy to the parallel energy dissipation resistor, and the energy dissipation resistor continuously consumes the gate-source charge during the pulse output stage;

[0098] When the self-triggered square wave pulse generator is in pulse cutoff mode, under the control of external signal, the P-MOSFETS p1 On, N-MOSFETS n1 Shutdown, C iss2 with C p2 Parallel, C issj is reversely charged to the P-MOSFET turn-on threshold voltage V gspth , N-MOSFETS of the j-th pulse generation circuit nj Immediately turn off, P-MOSFETS p1 Repeat this process until the main switches of the pulse generating circuits at all levels are all turned off and the shaping switches are all turned on;

[0099] When the self-triggered square wave pulse generator is in recovery mode, C iss with C p The parallel connection will pass through the parallel resistor R gs and the current limiting resistor releases the charge until C iss with C p When the voltage returns to zero potential, each switch returns to the working state of charging mode.

[0100] Example 12:

[0101] A self-triggering square wave pulse generator based on capacitor coupling energy extraction includes a power supply unit, a pulse generator main circuit, and a drive circuit.

[0102] In the main circuit of the pulse generator, each stage of the circuit contains an isolation diode, an N-MOSFET and a P-MOSFET; in the drive circuit, except for the first stage which is driven and controlled by an external signal, the remaining stages contain an energy-sampling capacitor and an energy-dissipating resistor.

[0103] The main switch and shaping switch in the Marx circuit are played by N-MOSFET and P-MOSFET connected in common source and common gate, and single drive control is achieved by inter-stage capacitor coupling.

[0104] A drain resistor is connected in parallel between the gate and source of the passively controlled switch, which can continuously consume the gate-source charge during the pulse output stage, thereby generating unbalanced charge and reversing the gate-source voltage polarity when the charge is redistributed at the trailing edge of the pulse, thereby meeting the negative voltage drive requirements of the P-MOSFET.

[0105] By selecting the switch type, energy-taking capacitor and gate-source resistance parameters, it is theoretically possible to achieve a charging voltage of 0-600V and an adjustable pulse width of 200ns-1000ns under single drive.

[0106] The pulse generator can output any number of modules.

[0107] Current limiting protection resistor (R c ), pulse shaping main circuit, drive circuit. In the pulse shaping main circuit, D1~D n For high voltage isolation diodes, C1~C n is the energy storage capacitor, S n1 ~S nn is the pulse shaping main switch, S p1 ~S pn It is a pulse shaping switch; in the driving circuit, the first stage S n1 and S p1 It is driven by an external control signal, and the rest of the levels are driven in sequence by capacitor coupling, including an energy-taking capacitor C p and a driving resistor R gs . C iss For switch S nn With S pn Common equivalent input capacitance. R L is the load resistance, and the circuit can generate a negative polarity high voltage pulse of nU0 on the load.

[0108] (1) Charging mode. Under the control of external signal, switch S n1 Shutdown, S p1 The other switches are in the off state, and the energy storage capacitors C1 to C n Via switch S p1 Or the P-MOSFET body diode is charged to U0.

[0109] (2) Pulse discharge mode. Under the control of external signal, the first stage switch S n1 conduction, S p1 Shutdown, C p2 -C iss2 The branch is charged by C1. iss2 The voltage across the terminals reaches the N-MOSFET turn-on threshold voltage (V gsnth ), the second-stage switch S n2 conduction, S p2Similarly, the third-stage switch S n3 conduction, S p3 At this point, all main switches at all levels are turned on, and a -3U0 pulse voltage output is generated on the load.

[0110] (3) Drive energy dissipation mode. In the flat-top stage of the output pulse, the equivalent input capacitors of each stage will release energy to the parallel energy dissipation resistor, but the energy-taking capacitor has no discharge path, making C iss with C p A charge imbalance occurs.

[0111] (4) Pulse cutoff mode. Under the control of external signal, switch S n1 Shutdown, S p1 conduction, C iss2 with C p2 In parallel, due to C p2 The charge is greater than C iss2 The charge, C iss2 is reversely charged to the P-MOSFET turn-on threshold voltage (V gspth ), the second-stage switch S n2 Will shut down immediately, S p2 It will be turned on immediately. Similarly, the third-stage switch S n3 Shutdown, S p3 Keep conducting. At this point, all main switches of each level are turned off and the shaping switches are turned on.

[0112] (5) Recovery mode. In this stage, C iss with C p The parallel connection will pass through the parallel resistor R gs And the current limiting protection resistor releases the charge, and finally C iss with C p When the voltage returns to zero potential, each switch returns to the working state of charging mode.

[0113] Parameter selection:

[0114] The equivalent circuit of the switch is shown in the figure, where each equivalent capacitor can be obtained from the C in the switch parameter manual. rss 、C oss and C iss Calculated. C iss is the sum of N-MOSFET and P-MOSFET, formula (1). The charging voltage is U0. The capacitor coupling self-triggered gate-source voltage is shown in the figure. The pulse discharge transient can be charged to V t1 , then slowly discharge to V t2 , reversely charged to V t3 .

[0115] C iss =Cgsn +C gsp +C gdn +C gdp (1)

[0116]

[0117] Formula (1) describes C iss is the sum of the equivalent input capacitance of N-MOSFET and P-MOSFET; Formula (2) describes the energy-taking capacitance C p With V t1 The calculation relationship between V t2 With (V t1 、R gs and C p )Calculation relationship, t w is the pulse discharge time; Formula (4) describes V t3 With (V t1 、V t2 and C p ) calculation relationship; Formula 5 limits V t1 、V t2 and V t3 The value range is determined by the gate threshold value and safe withstand voltage value of the switch.

[0118] Level 8 experimental prototype test:

[0119] Experimental parameters: charging voltage 500V, current limiting protection resistor 5kΩ, Marx level 8, main switch STP13NM60N, shaping switch IXTT16P60P, isolation diode HS5M, energy storage capacitor 2.2uF, energy extraction capacitor 220pF, energy dissipation resistor Rgs 390Ω, load resistor R L 1kΩ.

Claims

1. A self-triggered square wave pulse generator based on capacitive coupling, characterized by: It includes power supply unit, current limiting protection resistor, pulse shaping main circuit and driving circuit; The power supply unit supplies power to the pulse shaping main circuit through a current limiting protection resistor; The driving circuit adjusts the on / off of the switch tube of the pulse shaping main circuit so that the pulse shaping main circuit outputs pulses externally; The pulse shaping main circuit includes n-stage pulse generating circuits connected in series, each stage of the pulse generating circuit includes an isolation diode D i , energy storage capacitor C i 、N-MOSFET S ni and P-MOSFET S pi ; Among them, N-MOSFET and P-MOSFET serve as the main switch and shaping switch of the pulse shaping main circuit; i=1,2,…,n; The driving circuit includes a first-level external signal driving control unit and an n-1-level pulse driving unit; The pulse driving unit includes an energy-taking capacitor C p and energy dissipation resistor R gs ; Equivalent input capacitance C issj N-MOSFET S ni and P-MOSFET S pi The sum of equivalent input capacitance; The working modes of the self-triggered square wave pulse generator include charging mode, pulse discharge mode, drive energy dissipation mode, pulse cutoff mode, and recovery mode; When the self-triggered square wave pulse generator is in charging mode, the N-MOSFETS n1 Turn off, P-MOSFETS p1 The remaining switches in the pulse shaping main circuit are in the off state, and the energy storage capacitor C i Through the body diode of the first (i-2) P-MOSFET and the first-stage switch S p1 Charge to U0; U0 is the output voltage of the power supply unit; When the self-triggered square wave pulse generator is in pulse discharge mode, the N-MOSFETS n1 On, P-MOSFETS p1 Shutdown, C pj -C issj Branch C i Charging; when C issj The voltage across both ends reaches the N-MOSFET turn-on threshold voltage V gsnth When the N-MOSFETS of the j-th pulse generating circuit nj On, P-MOSFETS pj Turn off, repeat this process until the main switches of the pulse generating circuits at all levels are turned on, and a -nU0 pulse voltage output is generated on the load; j = i + 1; When the self-triggered square wave pulse generator is in the driving energy dissipation mode, the equivalent input capacitance of each stage of the pulse generating circuit releases energy to the parallel energy dissipation resistor, and the energy dissipation resistor continuously consumes the gate-source charge during the pulse output stage; When the self-triggered square wave pulse generator is in pulse cutoff mode, under the control of external signal, the P-MOSFETS p1 On, N-MOSFETS n1 Shutdown, C iss2 with C p2 Parallel, C issj is reversely charged to the P-MOSFET turn-on threshold voltage V gspth , N-MOSFETS of the j-th pulse generation circuit nj Immediately turn off, P-MOSFETS p1 Repeat this process until the main switches of the pulse generating circuits at all levels are all turned off and the shaping switches are all turned on; When the self-triggered square wave pulse generator is in recovery mode, C iss with C p The parallel connection will pass through the parallel resistor R gs and the current limiting resistor releases the charge until C iss with C p When the voltage returns to zero potential, each switch returns to the working state of charging mode.

2. The self-triggered square wave pulse generator based on capacitive coupling energy extraction according to claim 1, characterized in that: The external signal driving control unit receives the external control signal and transmits it to the first-stage pulse generating circuit, so that the N-MOSFET S n1 and P-MOSFET S p1 Driven by external control signal; Each pulse driving unit is connected to other driving pulse generating circuits except the first stage, so that the j-th driving pulse generating circuit is driven in sequence by capacitor coupling; j=2, 3, ... n.

3. The self-triggered square wave pulse generator based on capacitive coupling energy extraction according to claim 1, characterized in that: The energy dissipation resistor is used to continuously consume the gate-source charge during the pulse output stage, thereby generating unbalanced charge and reversing the gate-source voltage polarity during charge redistribution at the trailing edge of the pulse, thereby meeting the negative voltage drive requirements of the P-MOSFET.

4. The self-triggered square wave pulse generator based on capacitive coupling energy extraction according to claim 1, characterized in that: The output pulse voltage of the self-triggering square wave pulse generator is -nU0; U0 is the output voltage of the power supply unit.

5. The self-triggered square wave pulse generator based on capacitive coupling energy extraction according to claim 1, characterized in that: The charging voltage range of the self-triggering square wave pulse generator is 0-600V, and the pulse width range is 200ns-1000ns.

6. The self-triggered square wave pulse generator based on capacitive coupling energy extraction according to claim 1, characterized in that: The circuit topology of the pulse drive unit is as follows: Diode D i Series capacitor C i Back-connected P-MOSFET S pi ; Diode D i Connect N-MOSFET S ni ; N-MOSFET S ni and P-MOSFET S pi Cascode connection.

7. The self-triggered square wave pulse generator based on capacitive coupling energy extraction according to claim 6, characterized in that: In the pulse drive unit, the energy-taking capacitor C Pj Connected across the source of the previous stage switch and the gate of the current stage switch; j = 2, 3, ..., n; Energy dissipation resistor and N-MOSFET S ni connect.

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