Gallium nitride HEMT-based sliding mode driver special for deep hole drilling

Abstract

The invention discloses a sliding mode driver special for deep hole drilling based on a gallium nitride HEMT, and solves the problems of high-frequency vibration driving, multi-axis collaboration and electromagnetic interference suppression in deep hole processing through deep fusion of a wide bandgap semiconductor technology and an intelligent control algorithm. According to the main technical scheme, a GaN HEMT is adopted to construct a full-bridge power circuit, and feeding / translation dual-mode switching is achieved based on a matrix power bus. And designing a sliding mode surface containing an integral-differential item and a dynamic gain reaching law, inhibiting traditional sliding mode buffeting through synthesis of an equivalent control item and a switching control item, and realizing + / -2 [mu] m vibration amplitude tracking precision in combination with a high-frequency injection item and a gain adaptive mechanism. The LLC resonant converter based on the GaN HEMT is combined with model prediction control, and the PCB layout optimized by three-dimensional electromagnetic simulation is matched, so that the EMI noise is reduced, and the multi-axis collaborative electromagnetic compatibility is guaranteed. The GaN source inductance is reduced to be below 0.5 nH by adopting Kelvin connection and symmetric layout, 5-10ns self-adaptive dead zone adjustment is realized through a digital isolator, and reliable operation under a high-frequency working condition is ensured by combining a cascode driving structure and liquid cooling heat dissipation. The invention provides a new method for improving the deep hole machining efficiency.

Description

(1) Technical Field

[0001] The present invention relates to the field of precision mechanical drive technology, and specifically to a special sliding mode driver for deep hole drilling based on gallium nitride HEMT, which is applicable to drill control scenarios that require high current, high speed, and high-precision control in robots, precision machining equipment, etc. (2) Background Art

[0002] With the rapid development of power electronics technology, motor drivers are increasingly widely used in fields such as industrial automation, electric vehicles, and household appliances. Traditional motor drivers usually use silicon-based power devices (such as MOSFET or IGBT), which have been widely used in the past few decades and have promoted the progress of power electronics technology. However, with the continuous improvement of the performance requirements for motor drivers in application scenarios, the limitations of silicon-based power devices have gradually emerged.

[0003] From the research field of material characteristics, silicon-based power devices have a relatively low switching frequency, usually in the range of dozens of kilohertz (kHz), which limits the dynamic response speed and power density of motor drivers. Secondly, silicon-based devices generate relatively large energy losses during high-frequency switching processes, resulting in a decrease in system efficiency. Especially in high-power applications, the energy loss problem is particularly prominent. In addition, the on-resistance of silicon-based devices is relatively high, resulting in relatively large conduction losses under high-current conditions, further exacerbating the temperature rise problem. These factors not only affect the performance of motor drivers but also increase the difficulty and cost of heat dissipation design.

[0004] To solve the above problems, researchers have begun to explore the application of new semiconductor materials in power devices. Gallium nitride (GaN), as a wide-bandgap semiconductor material, has received extensive attention due to its excellent physical properties. Compared with silicon materials, gallium nitride has higher electron mobility, higher breakdown electric field, and lower on-resistance. These characteristics enable gallium nitride power devices to operate at higher switching frequencies while significantly reducing switching losses and conduction losses. In addition, the high-temperature operating ability of gallium nitride devices also gives them significant advantages in high-power applications.

[0005] Although gallium nitride HEMT (high electron mobility transistor) power devices have many theoretical advantages, their practical applications in the field of motor drives still face some technical challenges. Firstly, the drive circuit design of gallium nitride HEMT power devices is relatively complex, and precise control of the gate voltage is required to avoid device damage. Secondly, high-frequency switching operations introduce relatively large electromagnetic interference (EMI), which poses higher requirements for circuit layout and filtering design. In addition, the reliability and long-term stability of gallium nitride devices still need to be further verified, especially in harsh working environments (such as high temperature, high humidity, vibration, etc.).

[0006] Therefore, there is an urgent need for a special sliding mode driver for deep hole drilling based on gallium nitride HEMT to solve the above technical problems, give full play to the performance advantages of gallium nitride devices, and improve the overall performance and reliability of the motor driver. Based on this need, the present invention proposes an innovative design scheme for a sliding mode driver, aiming to achieve efficient, high-precision, and high-reliability motor drive. (III) Summary of the Invention

[0007] The present invention proposes a special sliding mode driver for deep hole drilling based on gallium nitride HEMT, which solves key technical problems such as high-frequency vibration drive, multi-axis coordinated control, and electromagnetic interference suppression in deep hole machining by integrating wide bandgap semiconductor technology and advanced control algorithms.

[0008] The present invention proposes a special sliding mode driver for deep hole drilling based on gallium nitride HEMT, and the method includes the following steps:

[0009] S1. Adopt the full-bridge topology dynamic reconstruction technology: Use GaN HEMT to construct a full-bridge power circuit, and realize the dynamic switching of the hardware architecture through the matrix power bus. In the feed mode, the full-bridge output drives the linear motor winding, and nanometer-level positioning accuracy is achieved based on sinusoidal PWM control; in the translation mode, switch to the rotary motor drive, and adopt the space vector modulation (SVPWM) algorithm to support wide speed range control of 0 - 6000 rpm, meeting the dual-mode requirements of axial feed and radial translation in deep hole drilling.

[0010] S2. Adaptive sliding mode control algorithm: Aiming at the tracking error problem of high-frequency chattering-assisted drilling, design a sliding mode surface including an integral term and a differential term, combine the dynamic gain adjustment reaching law, and suppress the chattering phenomenon of traditional sliding mode control through the component synthesis of the equivalent control term and the switching control term. The algorithm integrates a high-frequency injection term and a gain adaptive mechanism to compensate the cutting load disturbance in real time, ensuring the vibration amplitude tracking accuracy (±2μm) and the dynamic response speed.

[0011] S3. High-frequency resonant drive system: Based on the LLC resonant converter of GaN HEMT, utilize its nanosecond-level switching characteristics and zero reverse recovery loss to increase the switching frequency to the MHz level, reducing the power loss by 80%. Combine the model predictive control (MPC) algorithm to adjust the vibration waveform parameters in real time through rolling optimization, and optimize the PCB layout through three-dimensional electromagnetic simulation to suppress high-frequency EMI noise and ensure the electromagnetic compatibility of multi-axis coordinated control.

[0012] S4. Optimization Design of High-Frequency Half-Bridge Inverter: Aiming at the driving requirements of the deep hole drilling spindle motor, Kelvin connection and symmetric layout are adopted to reduce the parasitic inductance of GaN parallel devices (<0.5 nH). Combining with digital isolators, 5-10 ns adaptive dead-time regulation is realized to avoid shoot-through of the bridge arm. The drive circuit adopts a cascode structure, integrates an RC buffer network to suppress gate oscillation, and combines with a liquid cooling system to ensure the reliable operation of GaN devices under high-frequency conditions;

[0013] Further, the sliding mode surface of the sliding mode control algorithm described in step S2 that includes the vibration frequency tracking error is:

[0014] where e(t) = x(t) - x d (t) is the system state tracking error; A d sin(ω d t) is the desired vibration waveform, with the amplitude A d and frequency ω d adjustable; λ, η are the sliding mode surface adjustment parameters.

[0015] Further, the dynamic parameter reaching law of the sliding mode control algorithm described in step S2 is:

[0014] where k2(t) = k 2_base + α|e(t)| (α > 0 is the gain adjustment coefficient), γA d ω d cos(ω d t) is the high-frequency injection term, and ∈ is the smoothing factor.

[0016] Further, the final control input of the sliding mode control algorithm described in step S2 is:

[0017] u(t) = u eq (t) + u sw (t)

[0018] Equivalent control term:

[0019]

[0020] Switching control term:

[0021] where B is the control input matrix and f(x) is the system nonlinear model

[0022] The beneficial effects of the present invention are:

[0023] By combining the high-frequency characteristics of GaN devices with the sliding mode control algorithm, the present invention significantly improves the machining efficiency and surface quality of deep hole drilling. At the same time, through topology reconstruction and electromagnetic compatibility optimization, multi-axis collaborative control and stable operation under complex working conditions are achieved. In this field, a new method is provided for realizing vibration-assisted drilling. (IV) BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the system block diagram of a dedicated sliding mode driver for deep hole drilling based on GaN HEMT of the present invention;

[0025] Figure 2 is the structural block diagram of the switching module of a dedicated sliding mode driver for deep hole drilling based on GaN HEMT of the present invention;

[0026] Figure 3 is the flowchart of the sliding mode control algorithm of a dedicated sliding mode driver for deep hole drilling based on GaN HEMT of the present invention. (V) SPECIFIC EMBODIMENTS

[0027] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention.

[0028] As Figure 1 shown, the present invention constructs a full-bridge reconfigurable drive circuit based on GaN HEMT, and the core adopts a matrix power bus design. The topology dynamic switching is realized through a solid-state relay array controlled by FPGA:

[0029] (1) In the feed mode, the full-bridge output is connected to the linear motor winding, and the DSP generates a sinusoidal PWM wave with dead-time compensation, and realizes a positioning accuracy of ±5 nm through the GaN driver;

[0030] (2) When switching to the translation mode, the reconstructed bridge arm is connected to the spindle motor, and the SVPWM algorithm based on the flux observer is enabled, and the wide speed range control is realized in cooperation with the resolver feedback.

[0031] As Figure 2 shown, the implementation of the sliding mode control algorithm of the present invention includes three stages:

[0032] (a) Establish a vibration tracking error model, and collect the x(t) signal in real time through a laser displacement sensor, and compare it with the preset A d sin(ω d t) desired trajectory to generate e(t).

[0033] (b) Construct an adaptive sliding mode surface in the DSP, dynamically adjust the gain coefficient k2(t) according to the change of cutting load, and update the λ and η parameters through online identification by least squares.

[0034] (c) Adopt a double-loop control architecture. The inner loop calculates the equivalent control term u eq (t) based on a disturbance observer, and the outer loop generates the switching control term u sw (t) through a hysteresis comparator, and finally synthesize the modulation signal.

[0035] Implementation step 3: The hardware implementation of the high-frequency drive system includes:

[0036] (1) Adopt the LLC resonant network design to increase the switching frequency of the GaN HEMT to 2 MHz, and utilize its zero reverse recovery characteristic to reduce the resonant loss;

[0037] (2) Embed the MPC algorithm in the DSP, perform rolling optimization every 50 μs, and adjust the vibration amplitude in combination with the current loop prediction model;

[0038] (3) Adopt a six-layer PCB stacking design, insert a shielding layer between the power layer and the signal layer, optimize the impedance of the key signal path through Ansys HFSS simulation, and achieve EMI suppression in the 30 MHz - 1 GHz frequency band.

[0039] Implementation step 4: Construct a high-frequency half-bridge inverter:

[0040] (1) The power module uses two GaN HEMTs to form the upper and lower tubes, and each tube is configured with an independent Kelvin source lead-out. The loop inductance is reduced to 0.3 nH through the interleaved wire bonding process;

[0041] (2) The drive circuit uses a digital isolator, integrates the adaptive dead-time compensation function, and dynamically adjusts the dead-time according to the bus voltage fluctuation;

[0042] (3) Add a ferrite bead and a TVS tube in the gate drive loop to form a buffer network, and limit the dV / dt of the switching transient within 50 V / ns;

[0043] (4) The heat dissipation system uses a direct liquid-cooled substrate to ensure that the temperature of the GaN junction will not be too high.

[0044] The above-disclosed is only a preferred embodiment of the present invention. Of course, it cannot be used to limit the scope of the rights of the present invention. Those of ordinary skill in the art can understand the implementation of all or part of the above processes, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.

Claims

1. A special sliding mode driver for deep hole drilling based on gallium nitride HEMT, characterized in that The switching circuit can control a full-bridge motor drive circuit with GaN HEMT as the power conversion device to drive the feed motor and the translation motor in different application situations, realizing the hardware architecture of feed / translation dual-mode switching. The full-bridge topology reconstruction technology is adopted to realize the dynamic multiplexing of a single full-bridge circuit through a matrix power bus: (1) Feeding mode: The full-bridge output is connected to the linear motor winding and driven by sinusoidal PWM to achieve nanometer-level feeding accuracy; (2) Translation mode: The bridge arm is switched to rotary motor drive, space vector modulation (SVPWM) is enabled, and a wide speed range of 0-6000rpm is supported.

2. A sliding mode driver for deep hole drilling based on gallium nitride HEMT according to claim 1, characterized in that: A sliding mode control algorithm is added for chatter-assisted drilling, including the sliding mode surface of the vibration frequency tracking error: Where e(t) = x(t) - x d (t) is the system state tracking error; A d sin(ω d t) is the expected vibration waveform, amplitude A d , frequency ω d Adjustable; λ, η are sliding surface adjustment parameters. Dynamic parameter reaching law: Where k2(t)=k 2_base +α|e(t)|(α>0 is the gain adjustment coefficient),γA d ω d cos(ω d t) is the high frequency injection term, and ∈ is the smoothing factor. Final control input: u(t)=u eq (t)+u sw (t) Equivalent Controls: Toggle Controls: Where B is the control input matrix and f(x) is the nonlinear model of the system.

3. A sliding mode driver for deep hole drilling based on gallium nitride HEMT according to claim 1, characterized in that The use of gallium nitride power devices, with their wide bandgap semiconductor characteristics, shows significant advantages at the material level: high electron mobility supports nanosecond switching speeds, and the switching loss is reduced by up to 80% compared to traditional silicon-based IGBT devices. Since the jitter-assisted drilling is a precision machining technology, its core is to improve cutting efficiency through high-frequency axial vibration, which requires the drive system to have fast dynamic response capabilities. Therefore, the use of gallium nitride power devices provides a physical basis for building high-frequency resonant drive circuits. The LLC resonant converter is constructed using GaN HEMT devices, and the model predictive control (MPC) algorithm is implemented in conjunction with a digital signal processor (DSP), and the jitter amplitude accuracy is controlled within the range of ±2μm. Through the PCB layout optimized by three-dimensional finite element electromagnetic simulation, the system EMI noise is reduced by 15dBμV, providing electromagnetic compatibility guarantee for multi-axis collaborative control.

4. The deep hole drilling dedicated sliding mode driver based on gallium nitride HEMT according to claim 1, characterized in that: A high-frequency half-bridge inverter for deep hole drilling spindle motor is proposed, and the parallel layout of GaN devices is optimized to reduce parasitic inductance. The high-frequency half-bridge inverter consists of two GaN HEMTs, the middle node is connected to the motor winding, the upper and lower tubes are complementary switches, and the power is supplied by the DC bus; the Kelvin connection is used to separate the power circuit and the drive circuit, and the source inductance of the GaN device is reduced to below 0.5nH; a symmetrical PCB layout is used to balance the current distribution of parallel GaN devices; the reverse conduction characteristics of GaN devices are used to shorten the dead time to 5-10ns (traditional Si devices require 50-100ns); integrated digital isolators realize nanosecond-level dead time adaptive adjustment to avoid bridge arm direct conduction. The cascode drive structure (GaN+Si MOSFET combination) is adopted to improve the anti-interference ability of the drive, and an RC buffer circuit is added in the drive loop to suppress the gate oscillation caused by dV / dt.

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