Marx circuit switch tube driving non-magnetic core PCB coil driving structure

Abstract

The utility model belongs to high -voltage pulse power supply technical field, concretely for a kind of for MARX circuit switch tube drive's non-magnetic core PCB coil drive structure.The utility model drive structure adopts the non-magnetic core coil of PCB planarization wiring, primary coil and secondary coil are respectively laid in the different metal layer of same PCB, layer is separated by insulating medium, and energy and signal transmission are realized by electromagnetic coupling.Adjusting pulse parameter control gate level, so that it has voltage amplitude adjustable, wide dynamic range and fast level conversion characteristics, to adapt to the gate drive demand of different types power device.The utility model whole structure is more compact, it is convenient to multistage stack;Realization using PCB technology, without complex winding process, suitable for mass production and guarantee consistency.

Description

Technical Field

[0001] This utility model belongs to the field of high voltage pulse power supply technology, specifically relating to a coreless PCB coil driving structure. Background Technology

[0002] In an n-level all-solid-state Marx pulse source, there are numerous switching devices that need to operate in groups, and the switching actions of each group have a time difference. Therefore, the drive circuit must provide multiple independent drive signals. To prevent electromagnetic interference (EMI) or surge spikes on the high-voltage side from damaging the drive control chip, reliable electrical isolation must be provided between the drive side and the power side of the gate driver.

[0003] In existing literature, common isolation methods mainly include the following categories: optical fiber and magnetic transformers are two commonly used signal isolation methods in solid-state Marx generators. Optical isolation converts electrical signals into optical signals, transmits them via optical fiber, and then restores them to electrical signals in the optical receiver. This method has several advantages, including strong resistance to electromagnetic interference, high isolation voltage, support for long-distance transmission, and wide bandwidth. Magnetic isolation typically uses a multi-stage transformer structure with a shared primary winding connected in series. When the drive current passes through the series-connected primary winding, each secondary winding can synchronously obtain a trigger signal, which is a typical way to achieve synchronous control. Using a magnetic core to transmit the drive signal eliminates the need for an additional isolation power supply module and provides a high isolation voltage, which not only significantly improves the output amplitude of the drive signal but also reduces the overall cost of the pulse source.

[0004] However, using core transformers for isolation in all-solid-state Marx pulse sources has certain limitations. Each stage in a Marx circuit requires one or two core isolation transformers. The cores themselves are relatively large, and as the multi-stage stacking structure of Marx increases, the overall system size grows significantly, severely limiting the miniaturization of high-voltage pulse modules. Furthermore, core isolation transformers are prone to increased losses and deterioration of parasitic parameters at high frequencies, which also hinders the development of high-voltage pulse modules towards higher frequencies. Simultaneously, the cores have saturation limitations, restricting the signal pulse width, making them unsuitable for wide-pulse output applications.

[0005] In existing MARX circuits, the driving switching devices typically rely on core transformers for isolation and power transfer. However, core transformers are large, complex to wind, have limited bandwidth, and are difficult to arrange in multi-stage stacked MARX circuits, which is detrimental to the miniaturization and high-frequency operation of the system. Utility Model Content

[0006] The purpose of this invention is to provide a coreless PCB coil driving structure to replace the traditional core transformer in MARX circuits, thereby achieving miniaturization, integration, and high-frequency driving.

[0007] The present invention provides a coreless PCB transformer driving structure suitable for driving MARX circuit switching transistors. In the driving part, a coreless coil with PCB planar wiring is adopted. The primary coil and the secondary coil are respectively arranged on different metal layers of the same PCB, and the layers are separated by an insulating medium. Energy and signal transmission are achieved through electromagnetic coupling.

[0008] The driving mechanism of this novel drive structure is based on the energy storage and release characteristics of the magnetizing inductor in a coreless transformer: under the action of an excitation pulse, the primary-side magnetizing inductor first stores energy and then transfers the energy to the secondary side after the pulse ends, thereby completing the switching between positive and negative levels on the gate capacitor. Unlike traditional core transformers that rely on the core to directly transmit energy, this scheme can flexibly control the gate level by adjusting the pulse parameters, possessing characteristics such as adjustable voltage amplitude, wide dynamic range, and fast level transition, and can adapt to the gate driving requirements of different types of power devices.

[0009] The entire MARX circuit adopts a three-layer stacked structure, consisting of a primary excitation layer, a coreless transformer layer, and a secondary drive layer from top to bottom. Each PCB layer has pre-drilled pads and vias at corresponding locations, and vertical interconnection is achieved through soldering, forming a compact modular stacked structure. This design ensures the independence of each functional module while facilitating system miniaturization, integration, and multi-level cascading, meeting the application requirements of high-voltage pulse power supplies in terms of compactness and scalability.

[0010] The main technical features and advantages of this design are:

[0011] Compared with existing technologies, this invention eliminates the traditional magnetic core structure, making the driver more compact and facilitating multi-level stacking; it is implemented using PCB technology, eliminating the need for complex winding processes, making it suitable for mass production and ensuring consistency; its gate level can be flexibly adjusted, covering a wide dynamic range of negative voltage turn-off and positive voltage turn-on, thus adapting to the gate capacitance and rated voltage requirements of different types of power devices; at the same time, the three-layer stacked modular design effectively saves horizontal space, which is beneficial to the miniaturization and integration of MARX systems. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a coreless PCB transformer.

[0013] Figure 2 This utility model presents a partial illustration of the drive structure of a coreless PCB transformer.

[0014] Figure 3 This is a diagram of a three-layer stacked PCB driver module.

[0015] Figure 4 This is a diagram of a coreless coil and the MARX main circuit.

[0016] Figure 5 This is the rectangular wave output of the MARX prototype of this system under typical load.

[0017] Figure 6 This is the stepped rectangular wave output of the MARX prototype of this system under typical load. Detailed Implementation

[0018] like Figure 1 As shown, the coreless PCB transformer in this embodiment adopts a planar helical coil structure. Two coreless coils with planar PCB wiring are used as the primary coil and the secondary coil. The primary coil and the secondary coil are arranged on different metal layers of the PCB, separated by an insulating medium, thereby avoiding the defects of traditional core transformers, such as large size and complex winding.

[0019] The PCB dielectric material is FR-4, with a relative permittivity of approximately 4.4 and a dielectric strength greater than 20kV / mm. The transformer has a symmetrical double-layer planar spiral structure with an overall size of 15mm × 15mm. Both the primary and secondary coils have 15 turns, with an inner radius of approximately 2mm and an outer radius of approximately 7.2mm, and are respectively located on the top and bottom layers of the PCB.

[0020] like Figure 2 As shown, the circuit topology of the drive structure in this embodiment mainly consists of a primary-side excitation module, a coreless transformer isolation module, and a secondary drive module. Wherein:

[0021] The primary-side excitation module has a capacitor connected in parallel across its positive and negative terminals to provide a stable voltage for the full-bridge circuit. The full-bridge circuit consists of four MOSFET switches Q1, Q2, Q3, and Q4. Q1 and Q3 are connected in series on the left side of the DC power supply, and Q2 and Q4 are connected in series on the right side. The drains of Q1 and Q2, and the sources of Q3 and Q4, are connected to the positive and negative terminals of the DC bus, respectively. The midpoints of Q1 and Q3, and Q2 and Q4, serve as the two AC output terminals of the full bridge. An RC branch consisting of a resistor and a capacitor connected in parallel is connected in series between the two midpoints to absorb and balance energy. The AC output of the full bridge is connected to the primary winding of a coreless transformer.

[0022] The primary-side full-bridge output signal is coupled to the secondary-side winding through the primary side of the transformer.

[0023] The secondary drive module includes two power switches Q5 and Q6, four diodes D1, D2, D3, and D4, and six Zener diodes Z1, Z2, Z3, Z4, Z5, and Z6, with the following connections: the anode of D1 is connected to one end A of the transformer secondary winding, and the cathode is connected to the C terminal of capacitor C2; the anode of D3 is connected to the other end B of the secondary winding, and the cathode is also connected to the C terminal; the anode of D2 is connected to the C terminal of capacitor C, and the cathode is connected to the drain of power switch Q5; the anode of D4 is connected to the D terminal of capacitor D, and the cathode is connected to the drain of power switch Q6; the source of Q5 is connected to secondary winding A, and the source of Q6 is connected to secondary winding B. Zener diodes: Z1 and Z2 are connected in series and then in parallel across secondary terminals A and B, with the anode of Z1 connected to A, the anode of Z2 connected to B, and the cathodes connected together; Z3 and Z4 are connected across capacitors C and D respectively; the anode of Z5 is connected to the gate of Q5, and the cathode is connected to the drain of Q6; the anode of Z6 is connected to the gate of Q6, and the cathode is connected to the drain of Q5.

[0024] This driver mainly includes:

[0025] Primary excitation module: used to generate positive and negative polarity pulse signals;

[0026] Coreless PCB transformer: It consists of primary and secondary coils arranged on different layers of PCB, separated only by the PCB dielectric layer. It does not contain magnetic core material and relies on electromagnetic coupling to achieve signal and energy transmission.

[0027] Secondary drive module: Connected to the power switch in the MARX circuit, it receives pulses transmitted by the secondary coil and performs level shaping to reliably drive the switch to turn on or off.

[0028] The system driving process can be divided into the following four stages:

[0029] Phase 1: The primary-side excitation module generates a positive narrow pulse drive signal, which is coupled to the secondary side via a coreless transformer. In the secondary drive circuit, the gate capacitor is reverse-charged, thereby forming a negative voltage of a certain magnitude on the gate capacitor. At the same time, the primary-side magnetizing inductor is charged, storing electromagnetic energy to provide power for subsequent level changes.

[0030] Phase 2: As the positive pulse ends, the primary-side excitation module shuts down, and the magnetizing inductor of the coreless transformer begins to release its stored energy to the secondary side. This process transfers energy to the gate capacitor, causing it to transition from a negative voltage state to a positive voltage state, thus forming the positive drive level of the gate.

[0031] Phase 3: The primary-side excitation module generates a narrow negative pulse, which is transmitted to the secondary side through a coreless transformer, causing the gate capacitor to charge forward, thereby establishing a positive voltage across its terminals. Simultaneously, the primary-side magnetizing inductor recharges, storing energy to support the subsequent negative level switching.

[0032] Phase 4: After the negative pulse ends, the excitation module is turned off. The magnetizing inductor of the coreless transformer releases the stored energy to the secondary side, driving the gate capacitance to change in the negative voltage direction, thus achieving the negative voltage level required for turn-off.

[0033] like Figure 3 As shown, the three-layer stacked PCB driving system of this invention consists of a primary driving layer, a MARX and a coreless transformer layer, and a secondary driving layer. The middle layer comprises the MARX circuit body and the coreless PCB transformer, responsible for voltage superposition and signal isolation; the upper layer is the primary driving module, used to generate narrow pulses of positive and negative polarities; and the lower layer is the secondary driving module, connected to the power switching transistor, to complete the positive and negative switching of the gate voltage.

[0034] like Figure 4 As shown, the MARX circuit in this embodiment adopts a 12-stage series structure. Each stage includes two power switches. For example, the first stage includes Sa1 and Sb1, the second stage includes Sa2 and Sb2, and so on, with the 12th stage including Sa12 and Sb12, for a total of 24 switches. To ensure that each switch can obtain an independent gate drive signal, the system is designed with 24 drive channels. Correspondingly, the coreless transformer section of the intermediate layer integrates 24 planar spiral coil units, which are labeled one-to-one with the switch numbers: the primary side is labeled as Ta1 to Ta12, corresponding to Sa1 to Sa12 of stages 1 to 12; the secondary side is labeled as Tb1 to Tb12, corresponding to Sb1 to Sb12 of stages 1 to 12, and is used for signal coupling and isolation between the primary and secondary sides, respectively. The primary driver layer provides 24 positive and negative pulse signals, which are transmitted to the secondary driver layer via 24 coreless transformer units. The secondary driver layer then outputs the signals to the gates of 24 power switching transistors, thereby achieving precise synchronous driving of the entire MARX circuit.

[0035] The three-layer module has pre-reserved pads and vias at corresponding positions, and vertical electrical interconnection is achieved through soldering, forming a compact and reliable stacked drive system. This structure ensures both isolation and synchronization of multiple drive signals, and facilitates the miniaturization and mass production of the system, meeting the application requirements of multi-stage MARX circuits in high-voltage pulse power supplies.

[0036] The driver in this embodiment has been verified in a MARX circuit prototype. Test results show that the driving waveform remains stable within the operating frequency range of 1kHz to 200kHz; the gate level can be flexibly adjusted between -15V and +20V, meeting the driving requirements of various power devices such as SiC and GaN. With a three-layer stacked structure, the planar dimensions of a single driving unit are controlled to 25mm × 25mm, with a thickness of approximately 5mm. The overall system thickness after three-layer stacking is approximately 7cm, resulting in a compact structure suitable for multi-stage cascade applications.

[0037] Figure 5 and Figure 6 The system's MARX prototype demonstrates rectangular and stepped rectangular wave outputs under typical loads: steep rising / falling edges, stable and symmetrical positive and negative level amplitudes; the stepped wave exhibits consistent amplitudes at each step and smooth transitions between steps, demonstrating good channel synchronization and inter-stage consistency; meanwhile, modular stacking and independent channel driving support flexible configuration and expansion of the number of stages and steps.

[0038] The above results collectively verify that the proposed drive / isolation architecture and three-layer stacked structure can reliably drive multi-stage MARX circuits and obtain stable and controllable output waveforms within the operating range of 1kHz to 200kHz.

[0039] Furthermore, this invention is not limited to using FR-4 as the dielectric material; polyimide (PI), high-frequency and high-speed plates (such as the Rogers series), etc., can also be selected according to the withstand voltage and frequency requirements to improve insulation strength and high-frequency performance. The coil line width and spacing can be adjusted within the range of 0.1mm to 0.5mm, and the copper thickness is preferably 35μm to 70μm to meet different current carrying capacities.

[0040] Furthermore, the coreless transformer structure in the driver can employ not only helical coil arrangements but also concentric loop structures or staggered parallel line structures, thereby further optimizing the coupling coefficient and parasitic parameters. The three-layer stacked structure can also be expanded to four or more layers, for example, by adding an isolation layer or heat dissipation layer between the coreless transformer layer and the secondary drive module to improve system reliability and heat dissipation performance.

[0041] Since it contains no magnetic core material, the coreless transformer in this embodiment does not suffer from magnetic saturation, thus maintaining stable coupling performance even under high frequency and large amplitude pulses. The PCB solid-state structure has high mechanical reliability and thermal stability, avoiding the risks of magnetic loss and temperature rise at high frequencies inherent in traditional magnetic core transformers.

Claims

1. A coreless PCB coil driving structure for driving switching transistors in MARX circuits, characterized in that, A coreless coil employing PCB planar routing is used, in which the primary coil and secondary coil are respectively laid on different metal layers of the same PCB, separated by an insulating medium, and energy and signal transmission are achieved through electromagnetic coupling.

2. The coreless PCB coil driving structure for driving the switching transistor in a MARX circuit according to claim 1, characterized in that, By adjusting the pulse parameters to control the gate level, it can be made to have adjustable voltage amplitude, wide dynamic range and fast level switching characteristics, so as to adapt to the gate drive requirements of different types of power devices.

3. The coreless PCB coil driving structure for driving the switching transistor in a MARX circuit according to claim 2, characterized in that, The circuit topology consists of a primary-side excitation module, a coreless transformer isolation module, and a secondary drive module; wherein: The primary-side excitation module has a capacitor connected in parallel across its positive and negative terminals to provide a stable voltage for the full-bridge circuit. The full-bridge circuit consists of four MOSFET switches (Q1, Q2, Q3, Q4). The first and third MOSFET switches (Q1 and Q3) are connected in series on the left side of the DC power supply, and the second and fourth MOSFET switches (Q2 and Q4) are connected in series on the right side of the DC power supply. The drains of the first and second MOSFET switches (Q1 and Q2) and the sources of the third and fourth MOSFET switches (Q3 and Q4) are connected to the positive and negative terminals of the DC bus, respectively. The midpoints of the first and third MOSFET switches (Q1 and Q3) and the second and fourth MOSFET switches (Q2 and Q4) serve as the two AC output terminals of the full bridge. An RC branch consisting of a resistor and a capacitor connected in parallel is connected in series between the two midpoints to absorb and balance energy. The AC output of the full bridge is connected to the primary winding of a coreless transformer. The primary-side full-bridge output signal is coupled to the secondary-side winding through the primary side of the transformer; The secondary drive module includes two power switches (Q5, Q6), four diodes (D1, D2, D3, D4), and six Zener diodes (Z1, Z2, Z3, Z4, Z5, Z6), connected as follows: the anode of the first diode (D1) is connected to one terminal A of the transformer secondary, and the cathode is connected to terminal C of capacitor C2; the anode of the third diode (D3) is connected to the other terminal B of the secondary, and the cathode is also connected to terminal C; the anode of the second diode (D2) is connected to terminal C of capacitor C, and the cathode is connected to the drain of the first power switch (Q5); the anode of the fourth diode (D4) is connected to terminal D of capacitor D, and the cathode is connected to the drain of the second power switch (Q6); the source of the first power switch (Q5) is connected to secondary terminal A, and the source of the second power switch (Q6) is connected to secondary terminal B; the Zener diodes: the first and second Zener diodes (Z1 and Z2) are connected in series and then in parallel across terminals A and B of the secondary, wherein the first Zener diode (Z1) The anode of the first Zener diode (Z2) is connected to A, the anode of the second Zener diode (Z2) is connected to B, and the cathodes are connected together; the third and fourth Zener diodes (Z3 and Z4) are connected across capacitors C and D respectively; the anode of the fifth Zener diode (Z5) is connected to the gate of the first power switch (Q5), and the cathode is connected to the drain of the second power switch (Q6); the anode of the sixth Zener diode (Z6) is connected to the gate of the second power switch (Q6), and the cathode is connected to the drain of the first power switch (Q5).

4. The coreless PCB coil driving structure for driving the switching transistor in a MARX circuit according to any one of claims 1 to 3, characterized in that, The MARX circuit is a three-layer stacked structure, consisting of a primary excitation layer, a coreless transformer layer, and a secondary drive layer from top to bottom. Each PCB layer has pre-reserved pads and vias at corresponding positions, and vertical interconnection is achieved through soldering to form a compact modular stacked structure.

5. The coreless PCB coil driving structure for driving the switching transistor in a MARX circuit according to claim 4, characterized in that, The MARX circuit adopts a 12-stage series structure, with each stage including two power switches. Specifically, the first stage includes two power switches Sa1 and Sb1, the second stage includes two power switches Sa2 and Sb2, and so on, with the 12th stage including two power switches Sa12 and Sb12, for a total of 24 switches. To ensure that each switch can obtain an independent gate drive signal, 24 drive channels are designed. Correspondingly, the coreless transformer section of the intermediate layer integrates 24 planar spiral coil units, which are labeled one-to-one according to the switch numbers: the primary side is labeled as Ta1 to Ta12, corresponding to the power switches Sa1 to Sa12 of stages 1 to 12; the secondary side is labeled as Tb1 to Tb12, corresponding to the power switches Sb1 to Sb12 of stages 1 to 12, which are used for signal coupling and isolation between the primary and secondary sides, respectively. The primary driver layer provides 24 positive and negative pulse signals, which are transmitted to the secondary driver layer via 24 coreless transformer units. The secondary driver layer then outputs the signals to the gates of 24 power switching transistors, thereby achieving precise synchronous driving of the entire MARX circuit.

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