An ultrasonic drive source transducer based on gallium nitride devices and its control method.

Abstract

This invention provides an ultrasonic driving source transducer based on gallium nitride (GaN) devices and its control method. The ultrasonic driving source transducer includes: an auxiliary power supply system, a microcontroller driving circuit, a DC power supply, a full-bridge main circuit, a sampling circuit, a digital control module, and a signal filtering and biasing circuit. The auxiliary power supply system is connected to the microcontroller driving circuit, the digital control module, and the signal filtering and biasing circuit. The microcontroller driving circuit is connected to the digital control module, the signal filtering and biasing circuit is connected to the sampling circuit, and the digital control module is connected to the signal filtering and biasing circuit. The DC power supply is connected to the full-bridge main circuit, which is connected to both the microcontroller driving circuit and the sampling circuit. The full-bridge main circuit includes four MOSFETs made of gallium nitride. Due to the high switching speed of the MOSFETs, a PR control strategy is used on the microcontroller to cooperate with the external circuit, thereby achieving zero steady-state error tracking of the fundamental frequency and ensuring that the power supply always operates in the optimal state.

Description

[Technical Field]

[0001] This invention relates to the field of ultrasonic technology, and in particular to an ultrasonic driving source transducer based on gallium nitride devices and its control method. [Background Technology]

[0002] Ultrasonic welding is a special joining technology that is widely used in industry due to its characteristics such as fast welding speed, high weld strength, low requirements for surface cleaning of welded parts, and no restrictions on weldability in solid-state welding.

[0003] However, ultrasonic welding also has drawbacks. The power required for ultrasonic welding is related to the thickness and hardness of the workpiece, and the resonant point is affected by temperature and amplitude during the welding process, leading to a decrease in the power factor. With the development of ultrasonic technology, ultrasonic drive sources have received much attention from researchers. However, the problems of ultrasonic drive source transducers operating in the low-to-medium frequency range (40-50 kHz), insufficient tracking performance, and low power factor still need to be solved. [Summary of the Invention]

[0004] In view of this, embodiments of the present invention provide an ultrasonic driving source transducer based on gallium nitride devices and a control method thereof, in order to solve the problems that ultrasonic driving source transducers can only operate in the low-to-medium frequency range (40-50KHz), have insufficient tracking performance, and have low power factor.

[0005] On one hand, embodiments of the present invention provide an ultrasonic driving source transducer based on a gallium nitride device, comprising:

[0006] Auxiliary power supply system, microcontroller drive circuit, DC power supply, full-bridge main circuit, sampling circuit, digital control module and signal filtering and biasing circuit;

[0007] The auxiliary power supply system is connected to the microcontroller drive circuit, the digital control module, and the signal filtering bias circuit, respectively. The microcontroller drive circuit is connected to the digital control module, the signal filtering bias circuit is connected to the sampling circuit, the digital control module is connected to the signal filtering bias circuit, the DC power supply is connected to the full-bridge main circuit, and the full-bridge main circuit is connected to the microcontroller drive circuit and the sampling circuit.

[0008] The full-bridge main circuit includes four metal-oxide-semiconductor field-effect transistors (MOSFETs) made of gallium nitride.

[0009] Optionally, each metal-oxide-semiconductor field-effect transistor is connected in parallel with a diode.

[0010] Optionally, the positive terminal of the DC power supply is connected to the drain of the first metal-oxide-semiconductor field-effect transistor (MOSFET), the positive terminal of the DC power supply is connected to the drain of the second MOSFET, the negative terminal of the DC power supply is connected to the source of the third MOSFET, the negative terminal of the DC power supply is connected to the source of the fourth MOSFET, the source of the first MOSFET is connected to the drain of the third MOSFET, the source of the second MOSFET is connected to the drain of the fourth MOSFET, the midpoint of the upper and lower bridge arms of the first and third MOSFETs is connected to an LC filter circuit, and the midpoint of the upper and lower bridge arms of the second and fourth MOSFETs is connected to the LC filter circuit.

[0011] Optionally, the source of the first metal-oxide-semiconductor field-effect transistor and the drain of the third metal-oxide-semiconductor field-effect transistor are connected to an inductor, the source of the second metal-oxide-semiconductor field-effect transistor and the drain of the fourth metal-oxide-semiconductor field-effect transistor are connected to a capacitor, the inductor is connected to the capacitor, and the inductor and the capacitor are connected to a resistor.

[0012] Optionally, the resistor is connected in parallel with the voltmeter, and the resistor is also connected in parallel with the sampling circuit.

[0013] Optionally, the source of the first metal-oxide-semiconductor field-effect transistor and the drain of the third metal-oxide-semiconductor field-effect transistor are connected to the first end of an inductor; the source of the second metal-oxide-semiconductor field-effect transistor and the drain of the fourth metal-oxide-semiconductor field-effect transistor are connected to the second end of a capacitor; the second end of the inductor is connected to the first end of the capacitor; the second end of the inductor and the first end of the capacitor are connected to the first end of a resistor; and the second end of the capacitor is connected to the second end of the resistor.

[0014] Optionally, the digital control module includes a microcontroller.

[0015] Optionally, the microcontroller is used to implement a proportional resonant (PR) controller.

[0016] On the other hand, embodiments of the present invention provide a control method for an ultrasonic driving source transducer based on a gallium nitride device, applied to the aforementioned ultrasonic driving source transducer based on a gallium nitride device, the method comprising:

[0017] During the DC power supply process, the microcontroller outputs pulse width modulation (PWM) which, through the microcontroller drive circuit, controls the gate of the MOSFET, thereby controlling the switching transistor's on and off state. The voltage is taken from the midpoint of the two upper and lower bridge arms and output through an LC filter circuit.

[0018] The output voltage is sampled by the sampling circuit, the voltage divider resistor value is calculated to determine the transformation ratio, and the output voltage is taken out according to the voltage division ratio of the resistor. The taken voltage enters the signal filtering bias circuit.

[0019] The signal bias filter circuit filters the input signal and raises it according to the set bias voltage to obtain a positive voltage in the full range, so that the first data flowing into the microcontroller is within the sampling range of its analog-to-digital converter.

[0020] In the microcontroller, the first data collected is filtered by the amplitude limiting filter method, and then the root mean square method is used to obtain the effective value. The error is obtained by comparing the effective value with the expected value.

[0021] The parameters in the frequency domain are converted to the time domain by the PR controller. The PR controller is then used to compensate the loop in the time domain. The output of the PR controller controls the duty cycle of the PWM, which in turn controls the microcontroller drive circuit to drive the MOSFET.

[0022] On the other hand, embodiments of the present invention provide a gallium nitride MOSFET, which is applied to the above-mentioned ultrasonic drive source transducer based on gallium nitride devices.

[0023] The ultrasonic drive source transducer provided in this embodiment of the invention includes: an auxiliary power supply system, a microcontroller drive circuit, a DC power supply, a full-bridge main circuit, a sampling circuit, a digital control module, and a signal filtering bias circuit. The auxiliary power supply system is connected to the microcontroller drive circuit, the digital control module, and the signal filtering bias circuit. The microcontroller drive circuit is connected to the digital control module, the signal filtering bias circuit is connected to the sampling circuit, the digital control module is connected to the signal filtering bias circuit, the DC power supply is connected to the full-bridge main circuit, and the full-bridge main circuit is connected to the microcontroller drive circuit and the sampling circuit. The full-bridge main circuit includes four metal-oxide-semiconductor field-effect transistors made of gallium nitride. Due to the high switching speed of MOSFETs, a PR control strategy is adopted on the microcontroller to cooperate with the external circuit, thereby achieving zero steady-state error tracking of the fundamental frequency and ensuring that the power supply always operates in the optimal state. [Attached Image Description]

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A circuit diagram of an ultrasonic driving source transducer based on a gallium nitride device is provided in an embodiment of the present invention;

[0026] Figure 2 A circuit diagram of another ultrasonic drive source transducer based on a gallium nitride device provided in an embodiment of the present invention;

[0027] Figure 3 Bode plot of a PR controller provided in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram illustrating the relationship between breakdown voltage and on-resistance of different materials according to an embodiment of the present invention.

Detailed Implementation Methods

[0029] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0030] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0032] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0033] During operation, ultrasonic drive sources experience parameter variations due to various reasons, causing the frequency to deviate from the desired value. Therefore, frequency tracking technology is needed to address this issue. The influence of mains voltage also causes slight fluctuations in the ultrasonic power supply's output power, which can lead to various problems over time. Maintaining constant power is therefore crucial, requiring power control technology. Impedance matching is equally important in ultrasonic drive source design. It ensures that the input impedance equals the output impedance and can also be used for tuning, controlling the voltage and current to remain in phase to maximize output power.

[0034] There are several methods for frequency tracking and locking of ultrasonic transducers, including acoustic tracking and locking, electrical tracking and locking, maximum current tracking and locking, and phase-locked loop (PLL) tracking and locking. The acoustic tracking and locking method converts the transducer's mechanical oscillation into an electrical signal via acoustic coupling. This electrical signal is then phase-shifted, frequency-selected, and amplified to the desired frequency. The amplitude and phase information of the transducer can be detected to determine if the required resonant frequency has been reached. The electrical tracking and locking method involves loading a capacitor across the transducer and using the voltage across the capacitor for feedback. The peaking coil connected to the transducer needs to be adjusted to cause self-excited oscillation, operating at its resonant frequency. The maximum current tracking and locking method utilizes the minimum impedance at the resonant point. By continuously varying the frequency of the transducer's input voltage and judging the effective value of the output current, it determines whether the transducer is operating at its resonant frequency. Therefore, the transducer may operate in a non-resonant state throughout the process. The phase-locked loop (PLL) tracking method involves feedback within a voltage-controlled oscillator (VCO) and phase comparison with a given signal to obtain the phase difference signal. This phase difference signal contains high-frequency components, which require filtering by a loop filter. Finally, the high-frequency signal is fed back into the VCO to achieve automatic tracking. A comparison of the advantages and disadvantages of various transducer frequency tracking methods can be summarized in Table 1 below.

[0035] Table 1 As shown in Table 1 above, the acoustic tracking lock method has a simple circuit structure, but the transducer is both an action element and a sensing element, which has a significant impact on the measurement results; the electrical tracking lock method has a relatively simple acquisition circuit, but it is only used when the resonant point offset range is small, otherwise manual correction is required; the maximum current tracking lock method has a simple principle, but requires a long cycle; the phase-locked loop tracking lock method has high accuracy, but is prone to false locking and deadlock.

[0036] Compared with the above methods, the use of PR control combined with software algorithms in digital control technology can achieve frequency locking. Even if there is a deviation in the resonant frequency, the software algorithm will adjust the frequency and PR parameters according to the feedback to achieve frequency locking.

[0037] When digital control technology is applied to ultrasonic transducers, if the operating frequency of the power supply remains fixed at the previous resonant state, changes in load parameters will cause synchronous changes in the resonant frequency. This will result in a difference between the power supply output frequency and the load resonant frequency, thus failing to achieve the desired effect. Therefore, the power supply control strategy must consider multiple operating modes. Among these, using proportional resonant control (PR) at high operating frequencies (60K-80KHz) to achieve zero steady-state error tracking of the fundamental frequency is a better operating mode, ensuring that the power supply always operates in its optimal state. PR control is implemented by ensuring that the load has a sufficiently large open-loop gain at the output frequency, making the closed-loop curve infinitely close to 0dB at the output frequency, ultimately stabilizing the output frequency and achieving zero steady-state error tracking.

[0038] An embodiment of the present invention provides an ultrasonic driving source transducer based on a gallium nitride device. Figure 1 This is a circuit diagram of an ultrasonic driving source transducer based on a gallium nitride device, provided in one embodiment of the present invention. Figure 1 As shown, the ultrasonic drive source transducer includes: an auxiliary power supply system 1, a microcontroller drive circuit 2, a DC power supply 3, a full-bridge main circuit 4, a sampling circuit 5, a digital control module 6, and a signal filtering and biasing circuit 7.

[0039] The auxiliary power supply system 1 is connected to the microcontroller drive circuit 2, the digital control module 6, and the signal filtering bias circuit 7, respectively. The microcontroller drive circuit 2 is connected to the digital control module 6, the signal filtering bias circuit 7 is connected to the sampling circuit 5, the digital control module 6 is connected to the signal filtering bias circuit 7, the DC power supply 3 is connected to the full-bridge main circuit 4, and the full-bridge main circuit 4 is connected to the microcontroller drive circuit 2 and the sampling circuit 5.

[0040] The full-bridge main circuit 4 includes four metal-oxide-semiconductor field-effect transistors (MOSFETs) made of gallium nitride, a diode corresponding to each MOSFET, and an LC filter circuit.

[0041] Another ultrasonic drive source transducer based on gallium nitride devices is provided in one embodiment of the present invention. Figure 2A circuit diagram of another ultrasonic drive source transducer based on a gallium nitride device provided in an embodiment of the present invention is shown below. Figure 2 As shown, the ultrasonic drive source transducer includes: an auxiliary power supply system 1, a microcontroller drive circuit 2, a DC power supply 3, a full-bridge main circuit 4, a sampling circuit 5, a digital control module 6, and a signal filtering and biasing circuit 7.

[0042] The auxiliary power supply system 1 is connected to the microcontroller drive circuit 2, the digital control module 6, and the signal filtering bias circuit 7, respectively. The microcontroller drive circuit 2 is connected to the digital control module 6, the signal filtering bias circuit 7 is connected to the sampling circuit 5, the digital control module 6 is connected to the signal filtering bias circuit 7, the DC power supply 3 is connected to the full-bridge main circuit 4, and the full-bridge main circuit 4 is connected to the microcontroller drive circuit 2 and the sampling circuit 5.

[0043] In one embodiment of the present invention, the four metal-oxide-semiconductor field-effect transistors made of gallium nitride are a first metal-oxide-semiconductor field-effect transistor 41, a second metal-oxide-semiconductor field-effect transistor 42, a third metal-oxide-semiconductor field-effect transistor 43, and a fourth metal-oxide-semiconductor field-effect transistor 44. In one embodiment of the present invention, the positive terminal of the DC power supply 3 is connected to the drain of the first metal-oxide-semiconductor field-effect transistor 41, the positive terminal of the DC power supply 3 is connected to the drain of the second metal-oxide-semiconductor field-effect transistor 42, the negative terminal of the DC power supply 3 is connected to the source of the third metal-oxide-semiconductor field-effect transistor 43, the negative terminal of the DC power supply 3 is connected to the source of the fourth metal-oxide-semiconductor field-effect transistor 44, the source of the first metal-oxide-semiconductor field-effect transistor 41 is connected to the drain of the third metal-oxide-semiconductor field-effect transistor 43, the source of the second metal-oxide-semiconductor field-effect transistor 42 is connected to the drain of the fourth metal-oxide-semiconductor field-effect transistor 44, the midpoint of the upper and lower bridge arms of the first metal-oxide-semiconductor field-effect transistor 41 and the third metal-oxide-semiconductor field-effect transistor 43 is connected to an LC filter circuit, and the midpoint of the upper and lower bridge arms of the second metal-oxide-semiconductor field-effect transistor 42 and the fourth metal-oxide-semiconductor field-effect transistor 44 is connected to an LC filter circuit.

[0044] In one embodiment of the present invention, a first metal-oxide-semiconductor field-effect transistor 41 is connected in parallel with a first diode 45, a second metal-oxide-semiconductor field-effect transistor 42 is connected in parallel with a second diode 46, a third metal-oxide-semiconductor field-effect transistor 43 is connected in parallel with a third diode 47, and a fourth metal-oxide-semiconductor field-effect transistor 44 is connected in parallel with a fourth diode 48.

[0045] In one embodiment of the present invention, the source of the first metal-oxide-semiconductor field-effect transistor 41 and the drain of the third metal-oxide-semiconductor field-effect transistor 43 are connected to the inductor 49, the source of the second metal-oxide-semiconductor field-effect transistor 42 and the drain of the fourth metal-oxide-semiconductor field-effect transistor 44 are connected to the capacitor 50, the inductor 49 is connected to the capacitor 50, and the inductor 49, the capacitor 50 and the resistor 51 are connected.

[0046] In one embodiment of the present invention, resistor 51 is connected in parallel with voltmeter 52, and resistor 51 is connected in parallel with sampling circuit 5.

[0047] In one embodiment of the present invention, the source of the first metal-oxide-semiconductor field-effect transistor 41 and the drain of the third metal-oxide-semiconductor field-effect transistor 43 are connected to the first end of the inductor 49, the source of the second metal-oxide-semiconductor field-effect transistor 42 and the drain of the fourth metal-oxide-semiconductor field-effect transistor 44 are connected to the second end of the capacitor 50, the second end of the inductor 49 is connected to the first end of the capacitor 50, the second end of the inductor 49 and the first end of the capacitor 50 are connected to the first end of the resistor 51, and the second end of the capacitor 50 is connected to the second end of the resistor 51.

[0048] In one embodiment of the present invention, the digital control module 6 includes a microcontroller.

[0049] In one embodiment of the present invention, a microcontroller is used to implement a PR controller. The PR controller can increase the fundamental frequency, thereby effectively suppressing steady-state error. The PR controller adopts the following form:

[0050]

[0051] Among them, K p K is the proportionality coefficient. r ξ is the resonance coefficient, ξ1 and ξ2 are the damping ratios of the resonant element (ξ1 > ξ2), ω n G is the resonant angular frequency. i (s) is the transfer function of the PR controller.

[0052] Figure 3 A Bode plot of a PR controller provided in one embodiment of the present invention, such as Figure 3 As shown, the parameters are: ξ1 = 1, ξ2 = 0.01, ω n =100 at ω n It provides a large gain at ω, while at ω n A significant negative phase shift will be introduced in the vicinity. To minimize the impact of the negative phase shift on the phase margin, the cutoff frequency needs to be much greater than [the required frequency]. Compared to proportional-integral (PI) controllers, both modify the transfer function through gain. The difference lies in the PR controller's gain on the fundamental frequency, which is K. p +K r This is very advantageous for the fundamental frequency.

[0053] In one embodiment of the present invention, the material of the metal-oxide-semiconductor field-effect transistor includes gallium nitride.

[0054] Based on the aforementioned ultrasonic driving source based on gallium nitride (GaN) devices, one embodiment of this invention provides a control method for an ultrasonic driving source based on GaN devices. The principle of the GaN-based ultrasonic driving source transducer is that during the DC power supply 3, the microcontroller outputs pulse width modulation (PWM), which, through the microcontroller drive circuit 2, controls the gate of the GaN MOSFET, thereby controlling the switching transistor's on and off states. The voltage is taken from the midpoint of the two upper and lower bridge arms and filtered by an LC filter circuit to achieve voltage output. In transient analysis, the output waveform is accumulated from countless instantaneous chopping cycles. Therefore, the microcontroller needs to ensure that the duty cycle during the switching process changes sinusoidally. Simultaneously, a higher switching frequency is more beneficial to the output voltage. Macroscopically, the MOSFET will experience greater losses. This method enables open-loop control. In open-loop control, the output voltage changes due to variations in the input voltage, thus the voltage output cannot be stable. Based on this, a sampling circuit 5 samples the output voltage. The hardware determines the turns ratio by calculating the voltage divider resistor values. The output voltage is extracted according to the voltage division ratio of the resistors, and the extracted voltage enters the signal filtering and biasing circuit 7. The signal filtering bias circuit 7 filters the input signal, boosting it with a pre-set bias voltage and outputting a positive voltage across the entire range. This ensures the integrity of signal sampling to the maximum extent possible within the sampling range of the analog-to-digital converter (ADC) of the microcontroller. In the microcontroller, the acquired data is software-filtered using an amplitude-limiting filter, and the effective value is obtained using the root mean square method. This effective value is then compared with the expected value to obtain the error value. The error is compensated in the time domain using a PR controller. Theoretically, the parameters of the PR controller in the time domain are derived from the frequency domain. The output of the PR controller controls the duty cycle of the PWM signal, thereby controlling the microcontroller driver circuit 2 to drive the gallium nitride MOSFET.

[0055] One embodiment of the present invention provides a gallium nitride MOSFET that can be applied to the above-mentioned ultrasonic drive source transducer based on gallium nitride devices.

[0056] Gallium nitride (GaN) has attracted significant attention due to its high bandgap, high velocity, and high saturation electric intensity. GaN's larger bandgap—the energy required to ionize atoms and generate free electrons—is a fundamental characteristic that makes it highly attractive for high-power and high-temperature applications. Furthermore, its high charge carrier mobility and high saturation velocity are highly advantageous for high-current and high-frequency operation. Since the number of intrinsic carriers generated depends on the bandgap energy, a larger bandgap is a key factor in high-temperature operation and chemical inertness. High bandgap energy can also lead to a high intrinsic breakdown electric field, allowing for higher breakdown voltages. In recent years, improvements in material processing and device packaging have resulted in increasingly prominent features for GaN devices, including ultra-high blocking voltage, lower on-resistance, low switching losses, and adaptability to high-temperature operating environments.

[0057] Table 2 is a comparison table of the physical properties of various semiconductor materials, as shown in Table 2 below.

[0058] Table 2

[0059]

[0060] Figure 4 This is a schematic diagram illustrating the relationship between breakdown voltage and on-resistance of different materials according to an embodiment of the present invention, as shown in Table 2. Figure 4 It is evident that gallium nitride (GaN) possesses many superior properties compared to the previous two generations of semiconductor materials. GaN has a wider bandgap, directly determining the device's breakdown voltage and maximum operating temperature. Compared to the other three semiconductor materials, GaN has a lower relative permittivity, but it still maintains the conductivity expected of a semiconductor. (See Table 2...) Figure 4 It is known that the bandgap of gallium nitride (GaN) is three times that of silicon (Si), and the breakdown field strength of GaN is 3.3 × 10⁶ V / cm, which is 12 times that of Si (3 × 10⁵ V / cm), ensuring the high-voltage withstand capability of GaN devices. Using GaN MOSFETs with a larger bandgap in the main circuit structure offers several advantages. A larger bandgap results in higher electron mobility, leading to increased switching frequency, lower on-resistance, reduced switching losses, higher thermal conductivity for better heat dissipation, reduced system cooling requirements, higher breakdown field strength for higher voltage withstand levels, and faster saturation speed for faster switching speeds and better high-frequency characteristics.

[0061] In the technical solution provided by this invention, the ultrasonic drive source transducer includes: an auxiliary power supply system, a microcontroller drive circuit, a DC power supply, a full-bridge main circuit, a sampling circuit, a digital control module, and a signal filtering bias circuit. The auxiliary power supply system is connected to the microcontroller drive circuit, the digital control module, and the signal filtering bias circuit. The microcontroller drive circuit is connected to the digital control module, the signal filtering bias circuit is connected to the sampling circuit, the digital control module is connected to the signal filtering bias circuit, the DC power supply is connected to the full-bridge main circuit, and the full-bridge main circuit is connected to the microcontroller drive circuit and the sampling circuit. The full-bridge main circuit includes four metal-oxide-semiconductor field-effect transistors made of gallium nitride. Due to the high switching speed of MOSFETs, a PR control strategy is adopted on the microcontroller to cooperate with the external circuit, thereby achieving zero steady-state error tracking of the fundamental frequency and ensuring that the power supply always operates in the optimal state.

[0062] In the technical solution provided by the embodiments of the present invention, the ultrasonic drive source transducer adopts PR adjustment, such as... Figure 3 As shown, by utilizing the infinite gain characteristic of PR control at a fixed frequency point, theoretically, zero steady-state error tracking can be achieved. This invention takes a single-phase full-bridge as the research object and designs a digital control strategy using PR regulation in the high-frequency discrete domain (above 60kHz). It utilizes the fast response of the inner current loop combined with the proportional resonance of the outer voltage loop to obtain a high-precision tracking output voltage (60kHz-80kHz). Traditional PI control inevitably suffers from insufficient tracking performance in the closed-loop process, exhibiting phase and amplitude differences. PR control, however, can incorporate multiple resonant gain points based on system characteristics, suppressing harmonic components and effectively increasing the open-loop gain at the desired frequency. By changing the parameters, it is possible to achieve 0dB at the desired frequency point, realizing zero steady-state error tracking.

[0063] In the technical solution provided by the embodiments of the present invention, in combination with the requirements of the ultrasonic drive source transducer, a MOSFET made of gallium nitride process can be used, with a switching frequency of up to 2MHz, an internal resistance of 50mΩ, and a propagation delay of 20ns, ensuring a MHz-level operating frequency. The current process has reached the point where no external protection components are required, the overcurrent protection response time is less than 100ns, and low voltage protection is provided for all power rails.

[0064] The technical solution provided in this invention uses a control strategy to solve the problems in the prior art where the transducer operates in the low-to-medium frequency range (40 to 50 kHz), has low power, insufficient tracking performance, and low power factor.

[0065] This invention proposes a PR-controlled ultrasonic drive source transducer based on gallium nitride devices, which can provide ultrasonic drive source signals from 60kHz to 80kHz. When combined with a full-bridge circuit built with gallium nitride MOSFETs, it can generate a large power.

[0066] In the technical solution provided by the embodiments of the present invention, PR control is adopted for control. Compared with PI control, PR control can effectively suppress steady-state error and achieve zero steady-state error tracking. With the hardware combined with the third-generation semiconductor gallium nitride process MOSFET, the switching loss is effectively reduced at the same switching frequency.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ultrasonic driving source transducer based on gallium nitride devices, characterized in that, include: Auxiliary power supply system, microcontroller drive circuit, DC power supply, full-bridge main circuit, sampling circuit, digital control module and signal filtering and biasing circuit; The auxiliary power supply system is connected to the microcontroller drive circuit, the digital control module, and the signal filtering bias circuit, respectively. The microcontroller drive circuit is connected to the digital control module, the signal filtering bias circuit is connected to the sampling circuit, the digital control module is connected to the signal filtering bias circuit, the DC power supply is connected to the full-bridge main circuit, and the full-bridge main circuit is connected to the microcontroller drive circuit and the sampling circuit. The full-bridge main circuit includes four metal-oxide-semiconductor field-effect transistors (MOSFETs) made of gallium nitride. The digital control module includes a microcontroller, which is used to implement a proportional resonant (PR) controller. The PR controller adopts the following form: Among them, K p K is the proportionality coefficient. r ξ is the resonance coefficient, ξ1 and ξ2 are the damping ratios of the resonant element (ξ1>ξ2), ω n G is the resonant angular frequency. i (s) is the transfer function of the PR controller; The positive terminal of the DC power supply is connected to the drain of the first metal-oxide-semiconductor field-effect transistor (MOSFET), the positive terminal of the DC power supply is connected to the drain of the second MOSFET, the negative terminal of the DC power supply is connected to the source of the third MOSFET, the negative terminal of the DC power supply is connected to the source of the fourth MOSFET, the source of the first MOSFET is connected to the drain of the third MOSFET, the source of the second MOSFET is connected to the drain of the fourth MOSFET, the midpoint of the upper and lower bridge arms of the first and third MOSFETs is connected to an LC filter circuit, and the midpoint of the upper and lower bridge arms of the second and fourth MOSFETs is connected to the LC filter circuit.

2. The ultrasonic drive source transducer according to claim 1, characterized in that, Each metal-oxide-semiconductor field-effect transistor is connected in parallel with a diode.

3. The ultrasonic drive source transducer according to claim 1, characterized in that, The source of the first metal-oxide-semiconductor field-effect transistor and the drain of the third metal-oxide-semiconductor field-effect transistor are connected to an inductor; the source of the second metal-oxide-semiconductor field-effect transistor and the drain of the fourth metal-oxide-semiconductor field-effect transistor are connected to a capacitor; the inductor is connected to the capacitor; and the inductor and the capacitor are connected to a resistor.

4. The ultrasonic drive source transducer according to claim 3, characterized in that, The resistor is connected in parallel with the voltmeter, and the resistor is also connected in parallel with the sampling circuit.

5. The ultrasonic drive source transducer according to claim 3, characterized in that, The source of the first metal-oxide-semiconductor field-effect transistor and the drain of the third metal-oxide-semiconductor field-effect transistor are connected to the first end of an inductor. The source of the second metal-oxide-semiconductor field-effect transistor and the drain of the fourth metal-oxide-semiconductor field-effect transistor are connected to the second end of a capacitor. The second end of the inductor is connected to the first end of the capacitor. The second end of the inductor and the first end of the capacitor are connected to the first end of a resistor. The second end of the capacitor is connected to the second end of the resistor.

6. A control method for an ultrasonic drive source transducer based on gallium nitride devices, characterized in that, The method, applied to an ultrasonic drive source transducer based on a gallium nitride device as described in any one of claims 1 to 5, comprises: During the DC power supply process, the microcontroller outputs pulse width modulation (PWM) which, through the microcontroller drive circuit, controls the gate of the MOSFET, thereby controlling the switching transistor's on and off state. The voltage is taken from the midpoint of the two upper and lower bridge arms and output through an LC filter circuit. The output voltage is sampled by the sampling circuit, the voltage divider resistor value is calculated to determine the transformation ratio, and the output voltage is taken out according to the voltage division ratio of the resistor. The taken voltage enters the signal filtering bias circuit. The signal filtering bias circuit filters the input signal and raises it according to the set bias voltage to obtain a positive voltage in the full range, so that the first data flowing into the microcontroller is within the sampling range of its analog-to-digital converter. In the microcontroller, the first data collected is filtered by the amplitude limiting filter method, and then the root mean square method is used to obtain the effective value. The error is obtained by comparing the effective value with the expected value. The parameters in the frequency domain are converted to the time domain by the PR controller. The PR controller is then used to compensate the loop in the time domain. The output of the PR controller controls the duty cycle of the PWM, which in turn controls the microcontroller drive circuit to drive the MOSFET.

7. A gallium nitride MOSFET, characterized in that, Applied to the ultrasonic drive source transducer based on gallium nitride devices as described in any one of claims 1 to 5.

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