An ionization pulse generating device based on a phase-shifted half-bridge zero-voltage switching

Abstract

The application discloses an ionization pulse generation device based on a phase-shift half-bridge zero-voltage switch, which comprises a transformer isolation circuit, a driving and bootstrap circuit, a main switch circuit and a series resonance circuit. A control signal is input into the transformer isolation circuit, and is output to the driving and bootstrap circuit after being isolated by the transformer. The driving and bootstrap circuit drives and boots the switch tube in the main switch circuit according to the isolated control signal, so that a high-voltage direct-current signal is shaped into a pulse signal. In addition, the parallel capacitor of the MOS tube in the main switch circuit and the series resonance circuit constitute a resonance loop. Through continuous charging and discharging processes, the drain-source voltage of each MOS tube in the main switch circuit is reduced to 0 before being turned on and turned off, and zero-voltage switching is completed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of neutron generators, and more particularly relates to an ionization pulse generating device based on a phase-shifted half-bridge zero-voltage switch. BACKGROUND

[0002] A neutron generator is a self-controllable, monochromatic and portable neutron source, which can play an important role in nuclear logging, neutron irradiation, aerospace, medical treatment and other application scenarios, and the neutron generator is a controllable neutron source, which has no radioactivity when not working, and is more environmentally friendly and safe than traditional chemical sources. In response to the needs of national development, the demand for high-quality neutron generators in the market is also increasing, and the optimization of hardware circuit is the top priority of the current work.

[0003] The neutron yield of the neutron generator is determined by the filament current, ionization pulse and target pressure. The filament current releases deuterium-tritium gas by heating the tungsten filament, the deuterium-tritium gas is then ionized by the high-voltage ionization pulse to release deuterium-tritium ions, and finally the deuterium-tritium ions are accelerated by the target pressure to hit the target nucleus to generate neutrons. The ionization pulse directly determines the yield of deuterium-tritium ions, and the yield of deuterium-tritium ions directly determines the yield of neutrons. The design principle of the ionization pulse generating device is basically based on a bridge circuit, and the traditional ionization pulse generating device has large switching loss, which can cause the device to heat during operation, and even reduce the service life of the device over time.

[0004] The traditional ionization pulse generating device has the advantages of stable pulse waveform, small interference and the like, and is widely used in the technical field of neutron generators. However, there is still a lack of ionization pulse generating devices with simple circuit and zero-voltage switching characteristics. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide an ionization pulse generating device based on a phase-shifted half-bridge zero-voltage switch, which drives the main switch circuit by driving the MOS tube with the MOS tube, and at the same time increases the zero-voltage switching technology, so that the entire circuit is more simplified and the switching loss is reduced.

[0006] In order to achieve the above-mentioned purpose of the application, the ionization pulse generating device based on a phase-shifted half-bridge zero-voltage switch comprises:

[0007] A transformer isolation circuit comprises two transformers and four current-limiting resistors; each transformer has a primary winding and three secondary windings, and is used for electrical isolation to prevent mutual interference between voltage signals; the current-limiting resistors are connected in series across the primary windings of the transformers, and are used to limit the current in the circuit to prevent the current from being too large to burn out the devices; four low-voltage control signals RSON, RSOFF, LSON and LSOFF are input to the primary windings of the transformers, and are output from the secondary windings of the transformers to a driving and bootstrap circuit after being isolated by the transformers, so as to realize isolation between the low-voltage control signals and a direct-current high-voltage signal HV in a main switching circuit.

[0008] A driving and bootstrap circuit comprises 12 MOS transistors, each two MOS transistors form a group, and six groups of MOS transistors are respectively connected to six groups of secondary windings of the transformers in the transformer isolation circuit, so as to form six branches which have the same function and are used for driving and bootstrapping the main switching circuit.

[0009] In each group of MOS transistors, the gate of the first MOS transistor is connected to the non-polar end of the secondary winding of the transformer, the source is connected to the polar end of the secondary winding of the transformer, and the drain is connected to the gate of the second MOS transistor; the gate of the second MOS transistor is connected to the drain of the first MOS transistor, the source is connected to the non-polar end of the secondary winding of the transformer, and the drain is connected to the main switching circuit.

[0010] In the first branch, the driving and bootstrap process for one cycle of the main switching circuit is as follows: when RSON is high and RSOFF is low, the gate-source voltage difference Vgs1 of the MOS transistor Q1 is less than the turn-on voltage, so Q1 is turned off, and the source voltage of Q1 is applied to the drain through the body diode inside Q1, so that the gate-source voltage difference Vgs2 of the MOS transistor Q2 is greater than the turn-on voltage, thereby making Q2 conductive, and the drain voltage of Q2 is 0; at this time, in the main switching circuit, the gate-source voltage difference Vgs13 of the MOS transistor Q13 is greater than the turn-on voltage, so Q13 is turned on; when RSON is low and RSOFF is high, the gate-source voltage difference Vgs1 of the MOS transistor Q1 is greater than the turn-on voltage, so Q1 is turned on, and the drain voltage of Q1 is 0; at this time, the gate-source voltage difference Vgs2 of the MOS transistor Q2 is less than the turn-on voltage, so Q2 is turned off, and the source voltage of Q2 is applied to the drain through the body diode inside Q2; at this time, in the main switching circuit, the gate-source voltage difference Vgs13 of the MOS transistor Q13 is less than the turn-on voltage, so Q13 is turned off.

[0011] Similarly, the driving and bootstrap process for one cycle of the main switching circuit by the other branches is the same.

[0012] A main switch circuit comprises six groups of MOS tubes, diodes and capacitors; the gate and source of each MOS tube are respectively connected to the gate and drain of the second MOS tube in each group of MOS tubes in the driving and bootstrap circuit; the drain and source of each MOS tube are respectively connected in parallel with a diode and a capacitor, and the adjacent two MOS tubes are connected in series through the source and drain.

[0013] The drain of the first MOS tube Q13 is connected to an external input DC high voltage signal HV, and the source of the sixth MOS tube Q18 is connected to ground GND; when Q13, Q14 and Q15 are turned on and Q16, Q17 and Q18 are turned off, the main switch circuit outputs the DC high voltage signal HV; when Q13, Q14 and Q15 are turned off and Q16, Q17 and Q18 are turned on, the main switch circuit outputs a low voltage signal of 0V; thus the alternate turn-on and turn-off time of each MOS tube in the main switch circuit is controlled through the driving and bootstrap circuit, so as to obtain a pulse high voltage signal with a corresponding duty ratio.

[0014] A series resonant circuit comprises an inductor L r , a capacitor C r , a rectifier diode D r , a transformer T r and a load R L ; one end of the inductor L r is connected to the midpoint of the main switch circuit, and the other end is connected to the primary same end of the transformer T r ; one end of the capacitor C r is connected to the ground, and the other end is connected to the primary opposite end of the transformer T r ; the secondary of the transformer T r is connected in series with the rectifier diode D r and the load R L .

[0015] By controlling the switch timing of the main switch circuit, the inductor and capacitor in the series resonant circuit work in the resonant state, and form a charge and discharge circuit with the parallel capacitor in the MOS tube in the main switch circuit, so that the drain-source voltage of each MOS tube in the main switch circuit before being turned on and turned off is 0, and the zero voltage switch is completed.

[0016] The invention is achieved as follows:

[0017] This invention relates to an ionization pulse generation device based on a phase-shifted half-bridge zero-voltage switch, comprising a transformer isolation circuit, a drive and bootstrap circuit, a main switching circuit, and a series resonant circuit. A control signal is input to the transformer isolation circuit, isolated by the transformer, and then output to the drive and bootstrap circuit. The drive and bootstrap circuit drives and bootstraps the switching transistors in the main switching circuit according to the isolated control signal, thereby shaping the high-voltage DC signal into a pulse signal. Furthermore, the parallel capacitors of the MOSFETs in the main switching circuit and the series resonant circuit form a resonant circuit. Through continuous charging and discharging, the drain-source voltage of each MOSFET in the main switching circuit drops to 0 before being turned on and off, thus completing the zero-voltage switch.

[0018] Meanwhile, the ionization pulse generation device based on the phase-shifted half-bridge zero-voltage switch of the present invention also has the following beneficial effects:

[0019] (1) The use of transformer isolation circuit can effectively reduce the interference and influence of high voltage signal on low voltage signal;

[0020] (2) Compared with the form of driving MOS transistors by driving chips, the form of driving MOS transistors by MOS transistors designed in this invention makes the circuit more concise and the cost lower.

[0021] (3) Zero-voltage switching technology can minimize switching losses, reduce the heat generation of the switching transistor, and increase the service life of the device. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the ionization pulse generation device based on the phase-shifted half-bridge zero-voltage switch of the present invention;

[0023] Figure 2 This is a circuit diagram of the ionization pulse generation device based on the phase-shifted half-bridge zero-voltage switch of the present invention; Detailed Implementation

[0024] The specific embodiments of the present invention will now be described with reference to the accompanying drawings to enable those skilled in the art to better understand the invention. It should be particularly noted that in the following description, detailed descriptions of known functions and designs that might obscure the main content of the invention will be omitted here.

[0025] Example

[0026] Figure 1 This is a schematic diagram of the ionization pulse generation device based on the phase-shifted half-bridge zero-voltage switch of the present invention.

[0027] In this embodiment, as shown in FIG1, an ionization pulse generating device based on a phase-shifted half-bridge zero-voltage switch of the present invention includes: a transformer isolation circuit, a drive and bootstrap circuit, a main switch circuit and a series resonant circuit.

[0028] Now we combine Figure 2 The above four circuits and working process are described in detail as follows:

[0029] The transformer isolation circuit includes two transformers T1, T2 and four current-limiting resistors R1, R2, R3, R4; wherein the structure of each transformer is a primary and three secondaries, for electrical isolation to prevent mutual interference between voltage signals;

[0030] The current-limiting resistors are respectively connected in series at both ends of the transformer primary, for limiting the current size of the loop to prevent the burning of devices due to excessive current; four low-voltage control signals RSON, RSOFF, LSON, LSOFF are input by the transformer primary, and after isolation by the transformer, are output to the drive and bootstrap circuit by the secondary, to realize the isolation between the low-voltage control signal and the DC high-voltage signal HV in the main switch circuit;

[0031] In this embodiment, as shown in Figure 2 R1, R2 are connected in series at both ends of the transformer T1, and two low-voltage control signals RSON, RSOFF are input by the transformer T1 primary after passing through R1, R2, and are output to the drive and bootstrap circuit by the transformer T1 secondary after isolation by the transformer T1; R3, R4 are connected in series at both ends of the transformer T2, and two low-voltage control signals LSON, LSOFF are input by the transformer T2 primary after passing through R3, R4, and are output to the drive and bootstrap circuit by the transformer T2 secondary after isolation by the transformer T2

[0032] The drive and bootstrap circuit is composed of 12 MOS transistors, and each two MOS transistors form a group, as shown in Figure 2 Q1, Q2 form a group, Q3, Q4 form a group, and so on, Q11, Q12 form a group;

[0033] The six groups of MOS transistors are respectively connected to the six groups of transformer secondaries in the transformer isolation circuit, forming six branches with the same function, for driving and bootstrapping the main switch circuit;

[0034] Among each group of MOS transistors, the gate of the first MOS transistor is connected to the opposite end of the transformer secondary, the source is connected to the same end of the transformer secondary, and the drain is connected to the gate of the second MOS transistor; the gate of the second MOS transistor is connected to the drain of the first MOS transistor, the source is connected to the opposite end of the transformer secondary, and the drain is connected to the main switch circuit;

[0035] In this embodiment, as shown in Figure 2As shown, the gate of Q1 is connected to the opposite end of the secondary of transformer T1, the source of Q1 is connected to the same end of the secondary of transformer T1, the drain of Q1 is connected to the gate of Q2, the gate of Q2 is connected to the drain of Q1, the source of Q2 is connected to the opposite end of the secondary of transformer T1, and the drain of Q2 is connected to the main switch circuit;

[0036] As shown, when RSON is high and RSOFF is low, the gate-source voltage Vgs1 of Q1 is less than the threshold voltage, so Q1 is off, and the source voltage of Q1 is applied to the drain of Q1 through the body diode of Q1, so that the gate-source voltage Vgs2 of Q2 is greater than the threshold voltage, thus Q2 is on, and the drain voltage of Q2 is 0; as shown, Figure 2 As shown, the gate voltage of Q13 is the drain voltage of Q1, and the source voltage of Q13 is the drain voltage of Q2, so the gate-source voltage Vgs13 of Q13 in the main switch circuit is greater than the threshold voltage, thus Q13 is on; when RSON is low and RSOFF is high, the gate-source voltage Vgs1 of Q1 is greater than the threshold voltage, thus Q1 is on, and the drain voltage of Q1 is 0; at this time, the gate-source voltage Vgs2 of Q2 is less than the threshold voltage, thus Q2 is off, and the source voltage of Q2 is applied to the drain of Q2 through the body diode of Q2; as shown, Figure 2 As shown, the gate voltage of Q13 is the drain voltage of Q1, and the source voltage of Q13 is the drain voltage of Q2, so the gate-source voltage Vgs13 of Q13 in the main switch circuit is less than the threshold voltage, thus Q13 is off;

[0037] Similarly, the driving and bootstrap process of the other branches on the main switch circuit in one cycle is the same, which will not be described here;

[0038] The main switch circuit comprises six groups of MOS tubes, diodes and capacitors; the gate and source of each MOS tube are respectively connected to the gate and drain of the second MOS tube of each group of MOS tubes in the driving and bootstrap circuit, the drain and source of each MOS tube are respectively connected in parallel with a diode and a capacitor, and two adjacent MOS tubes are connected in series through the source and drain;

[0039] In this embodiment, as shown, Figure 2As shown, Q13, D1 and C1 form a group, the drain and source of Q13 are connected in parallel with D1 and C1 respectively, the gate and source of Q13 are connected to the gate and drain of Q2 in the driving and bootstrap circuit respectively, the drain of Q13 is connected to the input DC high voltage signal HV, the source of Q18 is connected to the ground GND, the source of Q13 and the drain of Q14 are connected between two adjacent MOS transistors, the source of Q14 and the drain of Q15 are connected, and so on, so that the six MOS transistors in the main switch circuit are connected in series;

[0040] When Q13, Q14 and Q15 are turned on and Q16, Q17 and Q18 are turned off, the main switch circuit outputs the DC high voltage signal HV, and when Q13, Q14 and Q15 are turned off and Q16, Q17 and Q18 are turned on, the main switch circuit outputs the low voltage signal of 0V; therefore, by controlling the alternating on and off time of each MOS transistor in the main switch circuit through the driving and bootstrap circuit, the pulse high voltage signal with corresponding duty ratio is obtained.

[0041] The series resonance circuit comprises an inductor L r , a capacitor C r , a rectifier diode D r , a transformer T r and a load R L ; one end of the inductor L r is connected to the midpoint of the main switch circuit, and the other end is connected to the primary same end of the transformer T r ; one end of the capacitor C r is connected to the ground, and the other end is connected to the primary opposite end of the transformer T r ; the secondary of the transformer T r is connected in series with the rectifier diode D r and the load R L .

[0042] By controlling the switching sequence of the main switch circuit, the inductor and capacitor in the series resonance circuit work in the resonance state, and form a charging and discharging circuit with the parallel capacitor of the MOS transistor in the main switch circuit, so that the drain-source voltage of each MOS transistor in the main switch circuit before being turned on and turned off is 0, thereby completing the zero voltage switching of the main switch circuit.

[0043] Now we will describe in detail the zero voltage switching process of one switching cycle T1-T5 of the main switch circuit in combination with the series resonance circuit, which is as follows:

[0044] At time Tl, Q13-Q15 are on, Q16-Q18 are off, at this time there are two loops of current in the main switch circuit and the series resonant circuit, one is composed of HV, Q13-Q15, Lr, Tr, Cr, GND, this loop makes HV act on the primary of Tr; the other is composed of HV, Q13-Q15, C4-C6, GND, this loop charges the capacitor C4-C6.

[0045] The circuit state changes from time Tl to time T2, Q13-Q15 are off, Q16-Q18 are off, at this time Q13-Q15 are off with zero voltage. Due to the resonant inductance characteristic, the current cannot be abruptly changed and still maintains the original flow direction, at this time there are two loops of current in the main switch circuit and the series resonant circuit, one is composed of HV, C1-C3, Lr, Tr, Cr, this loop charges the capacitor C1-C3; the other loop is composed of C4-C6, Lr, Tr, Cr, this loop discharges the capacitor C4-C6 until the capacitor C4-C6 is discharged to zero.

[0046] The circuit state changes from time T2 to time T3, Q13-Q15 are off, Q16-Q18 are on, because at this time the voltage across C4-C6 is zero, Q16-Q18 are on with zero voltage. Due to the resonant characteristic, the current on Lr drops to zero and reverses, at this time the loop of current in the main switch circuit and the series resonant circuit is composed of Lr, Q16-Q18, Cr, Tr.

[0047] The circuit state changes from time T3 to time T4, Q13-Q15 are off, Q16-Q18 are off, because at this time the voltage across C4-C6 is zero, Q16-Q18 are off with zero voltage. At this time there are two loops of current in the main switch circuit and the series resonant circuit, one is composed of Lr, C4-C6, Cr, Tr, this loop charges the capacitor C4-C6; the other loop is composed of Lr, C1-C3, HV, Cr, Tr, GND, this loop discharges the capacitor C1-C3 until C1-C3 is discharged to zero.

[0048] The circuit state changes from time T4 to time T5, Q13-Q15 are on, Q16-Q18 are off, because at this time the voltage across C1-C3 is zero, Q13-Q15 are on with zero voltage. The current on Lr drops to zero and reverses, at this time there are two loops of current in the main switch circuit and the series resonant circuit, one is composed of HV, Q13-Q15, Lr, Tr, Cr, GND, this loop makes the power voltage act on the primary of Tr; the other is composed of HV, Q13-Q15, C4-C6, this loop charges the capacitor C4-C6.

[0049] While the foregoing specific embodiments of the application have been described in some detail to provide a clear understanding thereof, it will be apparent to those of ordinary skill in the art that numerous modifications can be made to the specific embodiments described without departing from the spirit and scope of the application defined by the appended claims.

Claims

1. An ionization pulse generation device based on a phase-shifted half-bridge zero-voltage switch, characterized in that, include: A transformer isolation circuit includes two transformers and four current-limiting resistors. Each transformer has one primary and three secondary windings for electrical isolation, preventing interference between voltage signals. The current-limiting resistors are connected in series across the primary winding to limit the current in their respective circuits, preventing excessive current from burning out components. Four low-voltage control signals, RSON, RSOFF, LSON, and LSOFF, are input from the primary winding, isolated by the transformer, and then output from the secondary winding to the drive and bootstrap circuit, achieving isolation between the low-voltage control signals and the DC high-voltage signal HV in the main switching circuit. A drive and bootstrap circuit consists of 12 MOSFETs, with each pair of MOSFETs forming a group. The six groups of MOSFETs are individually connected to the secondary windings of the six transformers in the transformer isolation circuit, forming six branches with identical functions, used to drive and bootstrap the main switching circuit. In each group of MOSFETs, the gate of the first MOSFET is connected to the opposite terminal of the transformer secondary winding, the source is connected to the same terminal of the transformer secondary winding, and the drain is connected to the gate of the second MOSFET; the gate of the second MOSFET is connected to the drain of the first MOSFET, the source is connected to the opposite terminal of the transformer secondary winding, and the drain is connected to the main switching circuit. The first branch performs a one-cycle drive and bootstrap process for the main switching circuit as follows: When RSON is high and RSOFF is low, the gate-source voltage difference Vgs1 of MOSFET Q1 is less than the turn-on voltage, so Q1 is turned off. The source voltage of Q1 is applied to the drain through the body diode inside Q1, making the gate-source voltage difference Vgs2 of MOSFET Q2 greater than the turn-on voltage, thus turning Q2 on, and the drain voltage of Q2 is 0. At this time, in the main switching circuit, the gate-source voltage difference Vgs1 of MOSFET Q13... Since voltage 3 is greater than the turn-on voltage, Q13 is turned on. When RSON is low and RSOFF is high, the gate-source voltage difference Vgs1 of MOSFET Q1 is greater than the turn-on voltage, so Q1 is turned on, and the drain voltage of Q1 is 0. At this time, the gate-source voltage difference Vgs2 of MOSFET Q2 is less than the turn-on voltage, so Q2 is turned off, and the source voltage of Q2 is applied to the drain through the body diode inside Q2. At this time, in the main switching circuit, the gate-source voltage difference Vgs13 of MOSFET Q13 is less than the turn-on voltage, so Q13 is turned off. Similarly, the other branches drive the main switching circuit for one cycle in the same way as the bootstrap process. A main switching circuit includes six groups of MOSFETs, diodes, and capacitors; the gate and source of each MOSFET are individually connected to the gate and drain of the second MOSFET in each group of MOSFETs in the drive and bootstrap circuits, and a diode and a capacitor are connected in parallel across the drain and source of each MOSFET, and adjacent MOSFETs are connected in series through the source and drain connection. The drain of the first MOSFET Q13 is connected to the externally input DC high-voltage signal HV, and the source of the sixth MOSFET Q18 is grounded to GND. When Q13, Q14, and Q15 are turned on, and Q16, Q17, and Q18 are turned off, the main switching circuit outputs the DC high-voltage signal HV. When Q13, Q14, and Q15 are turned off, and Q16, Q17, and Q18 are turned on, the main switching circuit outputs a low-level signal of 0V. Therefore, by controlling the alternating on and off times of each MOSFET in the main switching circuit through the drive and bootstrap circuits, a pulse high-voltage signal with the corresponding duty cycle can be obtained. A series resonant circuit, including inductor L r Capacitor C r 1 Rectifier diode D r Transformer T r and load R L Inductance L r One end is connected to the midpoint of the main switch circuit, and the other end is connected to transformer T. r The primary terminal of the capacitor; capacitor C r One end is connected to ground, and the other end is connected to transformer T. r Primary heteronym terminal; transformer T r The secondary and rectifier diode D r and load R L Series; By controlling the switching timing of the main switching circuit, the inductor and capacitor in the series resonant circuit are made to work in a resonant state, and together with the parallel capacitor of the MOSFET in the main switching circuit, they form a charging and discharging circuit, so that the drain-source voltage of each MOSFET in the main switching circuit drops to 0 before being turned on and off, thus completing zero-voltage switching.

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