Self-triggering square wave pulse generator based on capacitance coupling energy taking

Abstract

The invention discloses a self-triggering square-wave pulse generator based on capacitive coupling energy taking. The self-triggering square-wave pulse generator comprises a power supply unit, a current-limiting protection resistor, a pulse shaping main circuit and a driving circuit, the power supply unit supplies power to the pulse shaping main circuit through the current-limiting protection resistor. The drive circuit adjusts on-off of a switching tube of the pulse shaping main circuit, so that the pulse shaping main circuit outputs pulses outwards. According to the invention, a discharge loop with a smaller time constant can be provided for gate-source charges, and the turn-off delay of each stage of the Marx circuit is improved; and meanwhile, a charging loop with a smaller time constant is provided for the equivalent output capacitor of the main switch, and the output trailing edge of each stage of the Marx circuit is shortened.

Description

Technical Field

[0001] The 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 biomedicine, plasma processing, food processing and other fields. In the practice of Marx circuits, since the potential rises step by step during pulse discharge, reliable switch isolation drive is required. Generally, switch isolation drive requires isolated transmission of control signals and isolated power supply for signal power amplification. Among them, a common method is to use a power converter based on magnetic coupling isolation with signal isolation (such as fiber optic converter, optical coupling chip, magnetic coupling chip, etc.). However, the use of magnetic coupling units (magnetic cores and coils) and signal isolation measures will increase the size and cost of the device. Another improved method integrates a core-coupled gate drive circuit, which can simultaneously transmit the control signal and drive energy to the switch to directly drive the switch, which does not require signal isolation measures and greatly reduces costs. However, the operating frequency of this method is limited by the fact that the magnetic core cannot be too low, and the conditioning circuit on the secondary side of the magnetic core increases the complexity of the system.

[0003] Unlike the magnetic coupling method that uses coil coupling, the capacitive coupling technology uses capacitor voltage division to extract 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 switch control of all levels of Marx through an external control signal without taking any isolation measures, which greatly reduces the system volume and complexity. However, in the switch-off phase, the charge stored in the capacitors at both ends of the gate source will be discharged through the load, and the charging of the switch equivalent output capacitor also passes through the load resistance. The larger time constant causes the switch to shut down slowly and gradually increase the shutdown delay, which will cause the output pulse to tail. This phenomenon is particularly significant under high impedance load conditions.

[0004] In summary, the current methods for switch isolation driving in Marx circuits mainly include magnetic coupling isolation technology and capacitive coupling technology. Although the capacitive coupling technology has a simple structure and is easy to operate and control, it has problems such as delayed shutdown and pulse tailing when the switch is under high resistance load. It is limited in square wave pulse output capability, which further limits 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 driving circuit;

[0006] The power supply unit supplies power to the pulse shaping main circuit via 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 ; Wherein, N-MOSFET and P-MOSFET are used 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 n1 and P-MOSFET S p1 Driven by external control signal;

[0012] Each pulse driving unit is respectively 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 output pulse voltage of the self-triggered square wave pulse generator is -nU 0 ; U 0 is the output voltage of the power supply unit.

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

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

[0017] The diode Di is connected in series with the capacitor Ci and then connected to the P-MOSFET S pi ;

[0018] Diode Di connects N-MOSFET S ni ;

[0019] N-MOSFETS 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 For N-MOSFET S ni and P-MOSFET S pi The sum of equivalent input capacitance;

[0023] Furthermore, the working modes of the self-triggered square wave pulse generator include a charging mode, a pulse discharge mode, a drive energy release 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 first (i-2) P-MOSFET and the first-stage switch S p1 Charge to USB 0 ; U 0 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 the two 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 -nU is generated on the load 0 Pulse voltage output; j = i + 1;

[0026] When the self-triggered square wave pulse generator is in the driving energy dissipation mode, the equivalent input capacitors of the pulse generating circuits at each level release energy to the parallel energy dissipation resistors, and the energy dissipation resistors continuously consume gate-source charges 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 The process is repeated 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 protection resistor releases the charge until C iss With C p The voltage returns to zero potential and 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 a complementary conduction state when the main switch and the shaping switch are working under single drive control.

[0030] The present invention proposes a negative voltage driving technology based on capacitive coupling energy extraction. By adding an energy dissipation 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 drive of a capacitive coupling single signal.

[0032] The present invention connects a gate-source resistor 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 loop with a smaller time constant for the gate-source charge, improve the turn-off delay of each level of the Marx circuit, and also provide a charging loop with a smaller time constant for the equivalent output capacitor of the main switch, shortening the output trailing edge of each level of the Marx circuit. Compared with the existing topology, this circuit can significantly shorten the tail of the pulse output as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is the overall structure of the pulse generator;

[0035] Figure 2 The circuit topology

[0036] Figure 3 The circuit topology of the self-triggered square wave pulse generator in different working modes; Figure 3 (a) for; Figure 3 (b) is pulse discharge mode; Figure 3 (c) is the driving energy dissipation mode; Figure 3 (d) is pulse discharge mode; Figure 3 (e) is recovery mode;

[0037] Figure 4 (a) is a simplified equivalent circuit; Figure 4 (b) is the self-triggered gate voltage;

[0038] Figure 5 It is a prototype of an 8-level self-triggered square wave pulse generator;

[0039] Figure 6 (a) is the output voltage of each level (pulse width 500ns); Figure 6 (b) is the load voltage waveform (pulse width 300-600ns). DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0041] Embodiment 1:

[0042] 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;

[0043] The power supply unit supplies power to the pulse shaping main circuit via a current limiting protection resistor;

[0044] 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;

[0045] 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 ; Wherein, N-MOSFET and P-MOSFET are used as the main switch and shaping switch of the pulse shaping main circuit; i = 1, 2, ..., n;

[0046] The driving circuit includes a first-level external signal driving control unit and an n-1-level pulse driving unit;

[0047] The pulse driving unit includes an energy taking capacitor and an energy dissipating resistor.

[0048] 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 S p1 Driven by external control signal;

[0049] Each pulse driving unit is respectively 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.

[0050] The energy dissipation resistor is used to continuously consume gate-source charge during the pulse output stage, thereby generating unbalanced charge, and reverse 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.

[0051] The output pulse voltage of the self-triggered square wave pulse generator is -nU 0 ; U 0 is the output voltage of the power supply unit.

[0052] The charging voltage range of the self-triggered square wave pulse generator is 0-600V, and the pulse width range is 200ns-1000ns.

[0053] The circuit topology of the pulse drive unit is as follows:

[0054] The diode Di is connected in series with the capacitor Ci and then connected to the P-MOSFET S pi ;

[0055] Diode Di connects N-MOSFET S ni ;

[0056] N-MOSFETS ni and P-MOSFET S pi Cascode connection.

[0057] 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;

[0058] The equivalent input capacitance Cissj is the sum of the equivalent input capacitance of N-MOSFET Sni and P-MOSFET Spi; the energy dissipation resistor is ni connect.

[0059] 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.

[0060] 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 USB 0 ; U 0 is the output voltage of the power supply unit;

[0061] 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 the two 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 -nU is generated on the load 0 Pulse voltage output; j = i + 1;

[0062] When the self-triggered square wave pulse generator is in the driving energy dissipation mode, the equivalent input capacitors of the pulse generating circuits at each level release energy to the parallel energy dissipation resistors, and the energy dissipation resistors continuously consume gate-source charges during the pulse output stage;

[0063] 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 The process is repeated until the main switches of the pulse generating circuits at all levels are all turned off and the shaping switches are all turned on;

[0064] 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 protection resistor releases the charge until C iss With C p The voltage returns to zero potential and each switch returns to the working state of charging mode.

[0065] Embodiment 2:

[0066] A self-triggering square wave pulse generator based on capacitor coupling energy extraction includes a power supply unit, a current limiting protection resistor, a pulse shaping main circuit, and a drive circuit;

[0067] The power supply unit supplies power to the pulse shaping main circuit via a current limiting protection resistor;

[0068] 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;

[0069] 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 ; Wherein, N-MOSFET and P-MOSFET are used as the main switch and shaping switch of the pulse shaping main circuit; i = 1, 2, ..., n;

[0070] The driving circuit includes a first-level external signal driving control unit and an n-1-level pulse driving unit;

[0071] The pulse driving unit includes an energy taking capacitor and an energy dissipating resistor.

[0072] Embodiment 3:

[0073] 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 S p1 Driven by external control signal;

[0074] Each pulse driving unit is respectively 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.

[0075] Embodiment 4:

[0076] 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 discharge resistor is used to continuously consume the gate-source charge in 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.

[0077] Embodiment 5:

[0078] A self-triggered square wave pulse generator based on capacitive coupling energy extraction, the technical content of which is the same as any one of Embodiments 2-4, further, the output pulse voltage of the self-triggered square wave pulse generator is -nU 0 ; U 0 is the output voltage of the power supply unit.

[0079] Embodiment 6:

[0080] 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.

[0081] Embodiment 7:

[0082] The self-triggered square wave pulse generator based on capacitive coupling energy extraction has the same technical content as any one of Embodiments 2-6. Furthermore, the circuit topology of the pulse driving unit is as follows:

[0083] The diode Di is connected in series with the capacitor Ci and then connected to the P-MOSFET S pi ;

[0084] Diode Di connects N-MOSFET S ni ;

[0085] N-MOSFETS ni and P-MOSFET S piCascode connection.

[0086] Embodiment 8:

[0087] 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;

[0088] Energy dissipation resistor and N-MOSFET S ni connect.

[0089] Embodiment 9:

[0090] A self-triggered square wave pulse generator based on capacitor coupling energy extraction, the technical content of which is the same as any one of Embodiments 2-8, and further, the equivalent input capacitance Cissj is the sum of the equivalent input capacitances of N-MOSFET Sni and P-MOSFET Spi;

[0091] Embodiment 10:

[0092] A self-triggered square wave pulse generator based on energy extraction through capacitive coupling, the technical content of which is the same as any one of Examples 2-9. Furthermore, the working modes of the self-triggered square wave pulse generator include a charging mode, a pulse discharge mode, a drive energy discharge mode, a pulse cutoff mode, and a recovery mode.

[0093] Embodiment 11:

[0094] 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. Further, 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 USB 0 ; U 0 is the output voltage of the power supply unit;

[0095] 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 the two ends reaches the N-MOSFET turn-on threshold voltage V gsnthWhen 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 -nU is generated on the load 0 Pulse voltage output; j = i + 1;

[0096] When the self-triggered square wave pulse generator is in the driving energy dissipation mode, the equivalent input capacitors of the pulse generating circuits at each level release energy to the parallel energy dissipation resistors, and the energy dissipation resistors continuously consume gate-source charges during the pulse output stage;

[0097] 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 The process is repeated until the main switches of the pulse generating circuits at all levels are all turned off and the shaping switches are all turned on;

[0098] 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 protection resistor releases the charge until C iss With C p The voltage returns to zero potential and each switch returns to the working state of charging mode.

[0099] Embodiment 12:

[0100] A self-triggering square wave pulse generator based on capacitor coupling energy extraction comprises a power supply unit, a pulse generator main circuit and a drive circuit.

[0101] 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 driving circuit, except for the first stage which is driven and controlled by an external signal, the remaining stages contain an energy-taking capacitor and an energy-discharging resistor.

[0102] The main switch and shaping switch in the Marx circuit are played by N-MOSFET and P-MOSFET connected with common source and common gate, and single drive control is realized by inter-stage capacitor coupling.

[0103] 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.

[0104] By selecting the switch, energy extraction 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.

[0105] The pulse generator can output any number of modules.

[0106] Current limiting protection resistor (R c ), pulse shaping main circuit, and driving circuit. In the pulse shaping main circuit, D 1 ~D n is a high voltage isolation diode, C 1 ~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 other stages are driven in sequence by capacitor coupling energy extraction, including an energy extraction 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, the circuit can generate nU on the load 0 Negative polarity high voltage pulse.

[0107] (1) Charging mode. Under the control of external signals, switch S n1 Shutdown, S p1 The other switches are in the off state, and the energy storage capacitor C 1 ~C n Via switch S p1 or the P-MOSFET body diode charges to U 0 .

[0108] (2) Pulse discharge mode. Under the control of external signals, the first-stage switch S n1 On, S p1 Shutdown, C p2 -C iss2 Branch C 1 Charging, when C iss2The voltage across the terminals reaches the N-MOSFET turn-on threshold voltage (V gsnth ), the second-stage switch S n2 On, S p2 Similarly, the third-stage switch S n3 On, S p3 At this point, all the main switches at each level are turned on, and -3U is generated on the load. 0 Pulse voltage output.

[0109] (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 resistors, but the energy-collecting capacitors have no discharge path, making C iss With C p There is a charge imbalance.

[0110] (4) Pulse cutoff mode. Under the control of external signal, switch S n1 Shutdown, S p1 On, 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 will be turned on immediately. Similarly, the third-stage switch S n3 Shutdown, S p3 Keep conducting. At this point, all the main switches of each level are turned off and the shaping switches are turned on.

[0111] (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 The voltage returns to zero potential and each switch returns to the working state of charging mode.

[0112] Parameter selection:

[0113] The switch equivalent circuit is shown in the figure, where each equivalent capacitor can be obtained from the C rss , C oss and C iss Calculated. C iss The sum of N-MOSFET and P-MOSFET, formula (1). The charging voltage is U 0 The capacitor-coupled 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 , in the pulse cut-off transient state, reversely charges to V t3 .

[0114] C iss =C gsn +C gsp +C gdn +C gdp (1)

[0115]

[0116]

[0117]

[0118]

[0119] Formula (1) describes C iss is the sum of the equivalent input capacitance of N-MOSFET and P-MOSFET; Formula (2) describes the energy extraction 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 according to the gate threshold and safe withstand voltage of the switch.

[0120] 8-level experimental prototype test:

[0121] 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 energy extraction, characterized in that: It includes a power supply unit, a current limiting protection resistor, a pulse forming main circuit, and a drive circuit. The power supply unit supplies power to the pulse shaping main circuit via 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 ; Wherein, N-MOSFET and P-MOSFET are used 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 the energy dissipation resistor R gs .

2. The self-triggered square wave pulse generator based on capacitive coupling energy extraction according to claim 1 is 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 of the first-stage pulse generating circuit n1 and P-MOSFET S p1 Driven by external control signal; Each pulse driving unit is respectively 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 is characterized in that: The energy dissipation resistor is used to continuously consume gate-source charge during the pulse output stage, thereby generating unbalanced charge, and reverse 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 is characterized in that: The output pulse voltage of the self-triggered 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 is characterized in that: The charging voltage range of the self-triggered 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 is characterized in that: The circuit topology of the pulse drive unit is as follows: The diode Di is connected in series with the capacitor Ci and then connected to the P-MOSFET S pi ; Diode Di connects N-MOSFET S ni ; N-MOSFETS 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 is 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; j=2,3,…,n. Energy dissipation resistor and N-MOSFET S ni connect.

8. The self-triggered square wave pulse generator based on capacitive coupling energy extraction according to claim 6 is characterized in that: Equivalent input capacitance C issj For N-MOSFET S ni and P-MOSFET S pi Sum of equivalent input capacitance.

9. The self-triggered square wave pulse generator based on capacitive coupling energy extraction according to claim 1, characterized in that: 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.

10. The self-triggered square wave pulse generator based on capacitive coupling energy extraction according to claim 9, characterized in that: 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 The first (i-2) P-MOSFET body diode 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 the two 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 all 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 capacitors of the pulse generating circuits at each level release energy to the parallel energy dissipation resistors, and the energy dissipation resistors continuously consume gate-source charges 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 The process is repeated 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 protection resistor releases the charge until C iss With C p The voltage returns to zero potential and each switch returns to the working state of charging mode.

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