Gallium nitride device application system suitable for frequency conversion refrigerator

Abstract

The invention relates to a gallium nitride device application system suitable for a frequency conversion refrigerator, which comprises a user interaction module for receiving temperature setting input of a user and generating a target temperature setting signal; the main control module receives a target temperature setting signal and receives a real-time temperature sampling signal from the temperature sensor; the drive control module receives a compressor start-stop control signal and generates a gallium nitride drive pulse signal based on the signal; the gallium nitride power module receives a gallium nitride driving pulse signal, controls the on-off state of a plurality of gallium nitride MOS devices based on the signal, and generates a high-frequency alternating current driving signal; the compressor module receives the high-frequency AC drive signal and operates at a variable speed based on the high-frequency AC drive signal. According to the gallium nitride device application system suitable for the frequency conversion refrigerator, the problems of low system efficiency, slow temperature control response and high operation noise caused by the use of a silicon-based power device in a traditional frequency conversion refrigerator can be solved.

Description

Technical Field

[0001] This invention relates to the field of frequency conversion drive and control technology for refrigeration equipment, and specifically to a gallium nitride device application system suitable for frequency conversion refrigerators. Background Technology

[0002] In the field of inverter refrigerators, the compressor's drive and control technology is the core factor affecting its energy efficiency, noise, and temperature control accuracy. Currently, most inverter refrigerators on the market use drive solutions based on insulated-gate bipolar transistors (IGBTs) or traditional metal-oxide-semiconductor field-effect transistors (MOSFETs). These silicon-based power devices have inherent limitations in their physical characteristics: First, their switching frequency is relatively low, which limits the modulation accuracy of the compressor drive waveform, resulting in large motor torque ripple and thus audible operating noise and vibration. Second, at higher operating frequencies, their switching and conduction losses increase significantly, which not only reduces the overall energy conversion efficiency of the drive board but also generates a large amount of heat, forcing the system to use a larger heat sink, increasing cost and size, and restricting the optimal layout of the refrigerator's internal space. Third, the slower switching speed causes a delay in the system's response to control commands, affecting the speed and accuracy of the temperature control loop, making it difficult to achieve rapid cooling or precise temperature fluctuation control.

[0003] With increasingly stringent energy-saving and environmental protection standards and rising user demands for quiet operation and precise temperature control, existing technologies are showing signs of bottlenecks. Although gallium nitride (GaN), as a wide-bandgap semiconductor material, theoretically possesses excellent characteristics such as high electron mobility, high critical breakdown electric field, and extremely low switching losses, making it highly suitable for high-frequency, high-efficiency power electronics applications, a mature and systematic solution has yet to be developed for the specific and complex application scenario of variable frequency refrigerators. This solution addresses the challenges of reliably and efficiently integrating GaN devices into existing temperature control and drive systems, and resolving a series of engineering issues related to drive protection, electromagnetic compatibility, and system adaptation. Therefore, developing an application system specifically designed for variable frequency refrigerators, deeply integrating the characteristics of GaN devices, and optimizing system architecture and control strategies is of significant practical importance for overcoming existing technological bottlenecks and enhancing product competitiveness. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a gallium nitride (GaN) device application system for variable frequency refrigerators, which solves the problems of low system efficiency, slow temperature control response, and high operating noise caused by the use of silicon-based power devices in traditional variable frequency refrigerators. This is achieved by reconstructing the compressor drive architecture with GaN power devices as the core. The system first uses a user interaction module to set the temperature and generate a target signal; the main control module compares the real-time temperature and generates a start / stop control signal; the drive control module receives this signal and, through its internal power factor correction, DC-DC conversion, and variable frequency control unit, generates a dedicated GaN drive pulse signal; the GaN power module, based on this pulse signal, controls the on / off state of multiple GaN devices at high speed and precision, generating a high-frequency AC drive signal; finally, the compressor module achieves stepless and smooth variable speed operation based on this high-frequency signal. The entire solution utilizes the high switching frequency and low conduction loss characteristics of GaN devices, combined with a closed-loop link from temperature control to drive, to achieve fast and precise temperature regulation, higher energy efficiency, and lower operating noise.

[0005] This invention provides a gallium nitride device application system suitable for frequency conversion refrigerators, comprising:

[0006] The user interaction module receives the user's temperature setting input and generates a target temperature setting signal.

[0007] The main control module receives the target temperature setting signal and the real-time temperature sampling signal from the temperature sensor. It generates compressor start / stop control signals by comparing the real-time temperature with the set temperature.

[0008] The drive control module receives the compressor start / stop control signal and generates a gallium nitride drive pulse signal based on the signal. The drive control module integrates a PFC circuit, a DC / DC conversion unit, and a frequency converter control unit to realize power factor correction, DC-DC conversion, and frequency conversion control of the input power supply.

[0009] Gallium nitride power module: The gallium nitride power module receives gallium nitride drive pulse signal and controls the on / off state of multiple gallium nitride MOS devices based on the signal to generate high-frequency AC drive signal;

[0010] The compressor module receives a high-frequency AC drive signal and operates at a variable speed based on the high-frequency AC drive signal;

[0011] The user interaction module, main control module, drive control module, gallium nitride power module, and compressor module are connected in sequence.

[0012] In one embodiment of the present invention, the user interaction module includes an input unit for receiving user touch or button operations and a display unit for displaying the refrigerator's operating status and set parameters. The input unit converts the user's temperature setting operation into a digital instruction and generates a target temperature setting signal. The display unit receives operating status feedback signals from the main control module and displays the current temperature, set temperature, and compressor operating status in real time. The user interaction module is connected to the main control module through an isolated communication line to ensure electrical isolation between the low-voltage control signals and the high-voltage drive components, thereby improving the system's anti-interference capability and human-machine interaction safety.

[0013] In one embodiment of the present invention, the main control module includes a microprocessor unit and a signal conditioning circuit. The signal conditioning circuit filters and amplifies the analog voltage signals collected by temperature sensors from multiple distributed locations, converts them into real-time temperature sampling signals, and transmits them to the microprocessor unit. The microprocessor unit has a pre-stored temperature control algorithm. By periodically comparing the numerical difference between the real-time temperature sampling signal and the target temperature setting signal, it dynamically generates a compressor start-stop control signal containing start, speed adjustment, and stop commands. This signal is further electrically isolated by an optocoupler and then transmitted to the drive control module.

[0014] In one embodiment of the present invention, the power factor correction circuit in the drive control module adopts an interleaved parallel topology to improve the harmonic suppression and power factor compensation effect of the AC input power supply. Its output terminal is connected to a high-voltage electrolytic capacitor to stabilize the DC bus voltage. The DC-DC conversion unit is an isolated resonant converter to convert the high-voltage DC power after correction and filtering into low-voltage DC power suitable for subsequent control. The frequency conversion control unit is a core control chip that generates a pulse width modulation signal with variable duty cycle and variable frequency as a gallium nitride drive pulse signal according to the frequency command inside the compressor start / stop control signal.

[0015] In one embodiment of the present invention, the gallium nitride power module includes a driver chip, a gate drive circuit, and multiple gallium nitride metal-oxide-semiconductor field-effect transistors with a full-bridge or half-bridge structure. The driver chip receives gallium nitride drive pulse signals and performs level conversion and current amplification. Then, the gate drive circuit generates a drive voltage that meets the fast switching requirements of gallium nitride devices. The turn-on and turn-off timing of each gallium nitride transistor is precisely controlled, thereby inverting DC power into a high-frequency AC drive signal with adjustable amplitude and frequency. The fundamental frequency of the signal changes continuously within a preset range according to the compressor speed regulation requirements.

[0016] In one embodiment of the present invention, the gallium nitride power module further includes a temperature detection unit and an overcurrent protection unit integrated thereon. The temperature detection unit monitors the junction temperature of the gallium nitride metal oxide semiconductor field-effect transistor in real time and generates a junction temperature feedback signal which is transmitted to the drive control module. The overcurrent protection unit collects the power circuit current in real time through a sampling resistor and generates a shutdown signal when the current exceeds a preset threshold. The frequency conversion control unit of the drive control module can receive the junction temperature feedback signal and the shutdown signal in real time, and dynamically adjust the parameters of the gallium nitride drive pulse signal or perform protective shutdown accordingly to prevent the gallium nitride device from being damaged due to overheating or overcurrent.

[0017] In one embodiment of the present invention, the compressor module is a scroll or rotary compressor driven by a brushless DC motor or a permanent magnet synchronous motor. It has an embedded position sensor for real-time detection of the motor rotor position and generation of a position feedback signal. The position feedback signal is fed back to the frequency converter control unit of the drive control module. The frequency converter control unit combines the speed command in the compressor start-stop control signal with the position feedback signal and uses a field-oriented control or direct torque control algorithm to correct the phase and frequency of the gallium nitride drive pulse signal in real time, thereby achieving smooth adjustment of the compressor speed and efficient and stable operation.

[0018] In one embodiment of the present invention, the system further includes a system power supply unit connected between the user interaction module, the main control module, and the drive control module. The system power supply unit draws power from the AC input power supply and sequentially passes through electromagnetic compatibility filtering, rectification, and multi-channel isolated DC-DC conversion steps to provide a first low-voltage DC power supply to the user interaction module, a second low-voltage DC power supply to the main control module and its auxiliary sensors, and a third low-voltage DC power supply to the control chip in the drive control module. Electrical isolation between the power supplies is achieved through isolation transformers or isolation power supply chips to ensure the stability and safety of the control system.

[0019] In one embodiment of the present invention, a bidirectional status communication link is also established between the main control module and the drive control module. While the main control module sends the compressor start-stop control signal to the drive control module, the drive control module feeds back the drive status signal to the main control module in real time, including the DC bus voltage value, power module temperature, output current value and fault code. The main control module is equipped with status monitoring logic, which can analyze the drive status signal and issue a warning message through the user interaction module when an abnormality is detected. At the same time, it adjusts or stops issuing the compressor start-stop control signal according to the preset strategy.

[0020] In one embodiment of the present invention, the temperature control algorithm executed by the main control module is an adaptive fuzzy proportional-integral-differential algorithm. This algorithm dynamically calculates and outputs a compressor target speed command based on the difference and rate of change between the real-time temperature sampling signal and the target temperature setting signal. The target speed command is encoded in the compressor start-stop control signal, enabling the system to adjust the compressor operating frequency nonlinearly and smoothly according to the changes in the internal heat load of the refrigerator. This achieves precise temperature control while minimizing frequent compressor start-stop and speed changes, improving energy efficiency and reducing operating noise.

[0021] This invention provides a gallium nitride (GaN) device application system for variable frequency refrigerators. The system addresses this issue by reconstructing the compressor drive architecture around GaN power devices. The system first uses a user interaction module to set the temperature and generate a target signal. The main control module compares the real-time temperature and generates a start / stop control signal. The drive control module receives this signal and, through its internal power factor correction, DC-DC conversion, and frequency conversion control unit, generates a dedicated GaN drive pulse signal. Based on this pulse signal, the GaN power module rapidly and precisely controls the switching on and off of multiple GaN devices, generating a high-frequency AC drive signal. Finally, the compressor module uses this high-frequency signal to achieve stepless and smooth variable speed operation. The entire solution utilizes the high switching frequency and low conduction loss characteristics of GaN devices, combined with a closed-loop link from temperature control to drive, to achieve rapid and precise temperature regulation, higher energy efficiency, and lower operating noise. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of 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.

[0023] Figure 1 This is a system architecture diagram for a gallium nitride device application system suitable for frequency conversion refrigerators;

[0024] Figure 2 A schematic diagram illustrating the working principle of one embodiment of the present invention. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0026] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0027] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0028] Please see Figure 1-2 The diagram illustrates a gallium nitride (GaN) device application system for a variable frequency refrigerator according to the present invention. The system includes a user interaction module that receives the user's temperature setting input and generates a target temperature setting signal; a main control module that receives the target temperature setting signal and a real-time temperature sampling signal from a temperature sensor, and generates a compressor start / stop control signal by comparing the real-time temperature with the set temperature; a drive control module that receives the compressor start / stop control signal and generates a GaN drive pulse signal based on the signal, wherein the drive control module integrates a PFC circuit, a DC / DC conversion unit, and a variable frequency control unit to achieve power factor correction, DC-DC conversion, and variable frequency control of the input power supply; a GaN power module that receives the GaN drive pulse signal and controls the on / off state of multiple GaN MOS devices based on the signal to generate a high-frequency AC drive signal; and a compressor module that receives the high-frequency AC drive signal and operates at a variable speed based on the high-frequency AC drive signal. The user interaction module, main control module, drive control module, GaN power module, and compressor module are connected sequentially.

[0029] Figure 1As shown, the system of this invention constructs a core control and drive architecture for a variable frequency refrigerator based on gallium nitride (GaN) power semiconductor technology. Its fundamental purpose is to comprehensively improve the operational efficiency, control precision, and reliability of the refrigerator compressor, a major energy-consuming component, through material innovation and system-level optimization. This system is not simply a replacement of GaN devices; rather, it reconstructs and deeply adapts the entire signal and control chain, from the human-machine interface to the final load, based on GaN's superior characteristics of high frequency, high efficiency, and high temperature resistance. This results in a highly collaborative, responsive, and significantly optimized energy conversion efficiency solution. The core working principle of the system is embodied in a clear closed-loop control process: it begins with the user setting their cooling needs, generates control commands through intelligent decision-making, then precisely converts electrical energy into the high-frequency drive energy required by the compressor through high-performance power electronic conversion, and finally completes temperature regulation through load execution, continuously feeding back the status for dynamic adjustments. Specifically, the physical and logical foundation of the entire system consists of a closely cooperating sequence of five modules. The initial module is the user interaction module, which is the only direct interface between the system and the user. It plays a crucial role in translating human subjective temperature control intentions into machine-readable and processable digital commands. Its operation involves receiving temperature setting inputs from the user via touchscreen, physical buttons, or knobs. This input is captured by the module's internal sensing and encoding circuitry, and after anti-shake and verification processes, a uniformly formatted and clearly defined digital signal—the target temperature setting signal. This signal not only contains the specific temperature value desired by the user but also typically carries additional instruction codes such as quick-cooling mode and energy-saving mode. Simultaneously, the user interaction module also integrates information feedback. Its internal display unit, whether an LCD screen or a digital tube array, continuously receives operational status feedback signals from downstream systems, particularly the main control module, and decodes these signals into visually understandable information. This includes real-time displays of the refrigerator's current temperature in the refrigerator and freezer compartments, the user's previously set target temperature, whether the compressor is in working or standby mode, and potential fault alarm icons. To ensure the safety and anti-interference capabilities of the control system, the user interaction module is not directly connected to the subsequent high-voltage or high-current control components. Instead, it uses an isolated communication line constructed with optocouplers or digital isolation chips to electrically isolate the generated target temperature setting signal before reliably transmitting it to the next stage—the main control module. This design effectively prevents interference signals such as voltage surges and ground noise from the power side from entering the low-voltage human-machine interface, ensuring user safety and improving system stability. As the brain and decision-making center of the entire control system, the main control module bears the heavy responsibility of information aggregation, logical judgment, and generation of core control commands.It continuously receives information streams from two key directions: first, the target temperature setting signal from the upstream user interaction module, representing the system's control objective; and second, real-time data from a network of temperature sensors distributed across multiple key temperature measurement points in the refrigerator, freezer, evaporator, and condenser. These temperature sensors, such as negative temperature coefficient thermistors or digital temperature sensors, convert the sensed temperature physical quantity into weak analog voltage or digital signals. These raw signals first enter the signal conditioning circuit of the main control module. The signal conditioning circuit is a preprocessing unit specifically designed to handle weak analog signals. Internally, it typically includes an amplification circuit composed of operational amplifiers to amplify the microvolt or millivolt-level sensor signals to a range suitable for analog-to-digital converter sampling; it also includes passive or active filtering circuits composed of resistors and capacitors to suppress high-frequency noise and power frequency interference introduced by sources such as the power supply and compressor motor, ensuring the purity and accuracy of the temperature sampling signal. The filtered and amplified signal is then converted into a standardized real-time temperature sampling signal and transmitted to the core of the module—the microprocessor unit. A microprocessor unit is a single-chip microcomputer with built-in or external memory, pre-stored with the temperature control algorithm program necessary for system operation. This algorithm periodically (e.g., several times per second) reads the real-time temperature sampling signal and compares it with the target temperature setpoint signal, calculating the temperature deviation and its rate of change. Based on these calculations, the microprocessor unit executes preset control logic. For example, when the actual temperature in the refrigerator compartment continuously exceeds the set temperature by a certain threshold, it determines that refrigeration needs to be activated, and dynamically generates a compressor start / stop control signal. This signal is not a simple switching quantity, but a digitally encoded instruction set containing rich control information, including at least a start or stop command identifier, the desired initial or target compressor operating frequency, and possible acceleration commands. Also for system safety and reliability considerations, the compressor start / stop control signal generated by the main control module typically passes through another electrical isolation barrier, such as an optocoupler, before being sent to the subsequent drive control module. The input of the optocoupler is driven by the microprocessor of the main control module, while the output is directly facing the drive control side. This achieves electrical isolation between the control circuit and the power drive circuit, effectively blocking the interference and potential damage risk to the precision control circuit caused by the ground potential fluctuations generated by the high-power switching action.

[0030] Specifically, the drive control module is the crucial bridge connecting low-voltage control and high-voltage drive, serving as the power conversion and signal generation center that transforms logical control commands into actual physical driving force. This module receives isolated compressor start / stop control signals from the main control module. Its primary task is to interpret the control intent contained in the signal: if it's a start command, it needs to prepare to generate the power signal to drive the compressor motor; if it's a stop command, it needs to safely shut off the power output. To achieve this goal, the drive control module highly integrates three functionally interconnected and collaborative core units: a power factor correction unit, a DC-DC conversion unit, and a frequency converter control unit. The power factor correction unit typically employs a boost converter topology based on a dedicated control chip. Its core function is to process the AC input power from the mains grid. Through high-frequency switching control, it forces the input current waveform to track the input voltage waveform, thereby raising the system's input power factor to near 1. This not only meets increasingly stringent international energy efficiency and electromagnetic compatibility standards and reduces harmonic pollution to the grid but also utilizes grid energy more effectively and reduces line losses. After power factor correction, the electrical energy is rectified and smoothed to form a stable high-voltage direct current (DC), which is stored in high-voltage electrolytic capacitors inside the module, forming the system's DC bus. The DC-DC converter unit is responsible for converting this high-voltage DC bus voltage into low-voltage DC power supplies of different voltage levels required by the frequency converter control unit and other auxiliary circuits. To ensure safety and suppress noise, this converter unit often uses an isolated topology, such as a flyback or LLC resonant converter, achieving electrical isolation through a high-frequency transformer to output stable and clean low-voltage DC. The soul of the entire module—the frequency converter control unit—is usually a digital signal processor or microcontroller specifically designed for motor drives. It deeply analyzes the frequency and speed commands in the compressor start-stop control signals, and combines them with its internally embedded motor control algorithms (such as space vector pulse width modulation algorithms) to generate a series of precisely timed pulse width modulation waveforms with dynamically adjustable duty cycles and frequencies, i.e., gallium nitride drive pulse signals. The characteristics of this signal are crucial; its frequency determines the fundamental frequency of the AC power that ultimately drives the compressor motor, while its duty cycle and modulation mode determine the effective value and waveform quality of the voltage applied to the motor, directly affecting the motor's torque, efficiency, and noise and vibration levels. In summary, from the user interaction module to the drive control module, the system completes an advanced control process from user intent acquisition to intelligent decision-making and drive command generation. The user interaction module initializes human-machine dialogue and command input, generating a clear target temperature setting signal; the main control module, as the central processing unit, integrates target setting and environmental feedback, and generates compressor start-stop control signals containing complex operating strategies through intelligent algorithms; the drive control module, as a professional power-to-signal converter, translates and amplifies the logic control signals into precise gallium nitride drive pulse signals that can directly command subsequent gallium nitride power switching actions.These three modules are progressively layered, with the signal form evolving from temperature settings representing human thought to digital codes representing machine instructions, ultimately transforming into pulse sequences that precisely control the switching timing of power semiconductors. This lays a solid foundation for subsequent high-efficiency power conversion and motor drive. The entire front-end signal chain design fully considers electrical isolation, noise suppression, signal fidelity, and intelligent control, ensuring that control intentions can be accurately, stably, and safely transmitted and executed under complex electromagnetic environments and long-term operating conditions. This is the prerequisite and guarantee for the reliable and efficient operation of the entire gallium nitride inverter drive system. The subsequent gallium nitride power modules and compressor modules are powerful actuators under these precise instructions, working together to complete the ultimate mission of efficiently converting electrical energy into cooling capacity.

[0031] Furthermore, the core actuator and energy conversion link of the system described in this invention are specifically embodied in the physical implementation and fine-tuning process from the drive control module to the compressor module. This part converts logical instructions into actual mechanical work, and its performance directly determines the energy efficiency, noise, vibration, and control accuracy of the entire refrigerator system. The drive control module, as a crucial link between the upper and lower layers, has an extremely precise internal structure and working mechanism. The power factor correction circuit integrated in this module is not a simple boost chopper, but rather employs a more advanced multiphase interleaved parallel topology. In this architecture, two or more power factor correction units with identical structures operate in parallel, but their high-frequency switching control signals are phase-shifted. This design offers several core advantages: First, it significantly increases the ripple frequency of the input current while substantially reducing its amplitude. This translates to superior harmonic suppression of the front-end AC input power supply, easily meeting the most stringent electromagnetic compatibility standards. Second, the interleaved parallel connection reduces the effective current flowing through individual magnetic components and switching devices, minimizing component conduction losses and temperature rise, and improving local reliability. Finally, it enhances the system's power handling capacity and dynamic response speed. After deep correction and processing by this circuit, the current and voltage waveforms are essentially in phase, achieving an extremely high power factor and enabling high-quality, high-efficiency utilization of grid power. The high-voltage DC output from the correction circuit is not used directly but is instead supplied to a substantial high-voltage electrolytic capacitor bank for energy storage and smoothing. These capacitors act like a stable energy reservoir, absorbing minor fluctuations from the input side and providing instantaneous high-current support for the subsequent inverter stage. This ensures that the DC bus voltage remains stable even under sudden changes in compressor load, forming the cornerstone of the entire power conversion chain's reliable operation. Following this is the DC-DC converter unit, whose core task is to safely and efficiently convert the hundreds of volts from the high-voltage DC bus into low-voltage DC power, such as 12 volts, 5 volts, or 3.3 volts, required by the logic circuits, control chips, and potentially front-end sensing circuits of the drive control module. To achieve this goal and ensure system safety, this unit commonly employs isolated resonant converter technology, such as an inductor-inductor-capacitor resonant converter. This topology utilizes the resonant characteristics of inductors and capacitors, enabling the main power switching transistors to perform switching operations under zero voltage or zero current conditions—the so-called soft switching. Soft switching technology virtually eliminates the losses caused by voltage and current overlap during the switching process, raising the efficiency of DC-DC conversion to unprecedented levels. Simultaneously, electrical isolation is achieved through the magnetic coupling of a high-frequency transformer, completely separating the high-voltage and low-voltage sides. This not only ensures the safety of personnel and equipment in the subsequent low-voltage control circuits but also completely blocks the transmission of power ground noise to sensitive control ground, creating a clean operating environment for the frequency converter control unit. This unit typically provides multiple independent and isolated outputs, supplying different functional circuits respectively, further avoiding common ground interference.

[0032] In one embodiment of the present invention, the intelligent core of the entire drive control module—the frequency converter control unit—is a highly integrated dedicated motor control chip or digital signal processor. It receives and decodes the compressor start / stop control signal from the main control module, the target speed or frequency command contained within which forms the basis of its operation. However, its function extends far beyond simple signal forwarding. The unit internally incorporates complex motor control algorithms, such as space vector pulse width modulation (SVM). This algorithm can more fully utilize the DC bus voltage, generating pulse width modulation waveforms with lower harmonic content and higher voltage utilization. Based on the target speed, the frequency converter control unit calculates and generates in real time a set of pulse width modulation signals with a specific frequency, a specific phase difference, and a duty cycle that varies sinusoidally—the aforementioned gallium nitride drive pulse signal. The fundamental frequency of this signal determines the final AC frequency applied to the compressor motor, while its modulation method determines the waveform quality and voltage amplitude of the AC power. To achieve smoother and more energy-efficient control, the unit also integrates soft-start and soft-stop control logic. Upon receiving the start command, the drive signal at the target frequency is not immediately output. Instead, the soft-start logic controls the output frequency to gradually increase from zero Hz along a preset, gentle slope curve (e.g., increasing by a few Hz per second) to the target value. Correspondingly, during shutdown, the soft-stop logic controls the frequency to smoothly decrease from the current value to zero along a preset slope. This process, through the subsequent power module, enables the compressor motor to achieve slow acceleration and deceleration, fundamentally suppressing the huge starting current surge and mechanical stress caused by traditional hard start-stop, playing a decisive role in extending compressor bearing life and reducing starting noise. The gallium nitride drive pulse signal generated by the drive control module is precisely sent to the gallium nitride power module. This module is where the fundamental transformation of electrical energy occurs and is the key stage for the properties of gallium nitride materials to be fully utilized. Its core components include a dedicated drive chip, a gate drive circuit, and a full-bridge or half-bridge power switch array composed of multiple gallium nitride metal-oxide-semiconductor field-effect transistors. Due to the extremely low gate charge and extremely fast switching speed of gallium nitride devices, traditional drive circuits are no longer suitable. Therefore, a dedicated driver chip is responsible for receiving the pulse width modulation signal from the frequency converter control unit and performing necessary level shifting and current amplification. Subsequently, a carefully designed gate drive circuit generates a drive voltage that meets the requirements of gallium nitride (GaN) devices, possessing precise timing and sufficient drive capability. This drive voltage must have very steep rise and fall edges to ensure that the GaN transistors can operate within their optimal switching range, while also avoiding excessively fast edges that could cause severe electromagnetic interference and voltage overshoot. Under the control of the drive signal, the upper and lower arm GaN transistors in the full-bridge or half-bridge circuit alternately turn on and off according to a strict interlocked timing sequence, "cutting" and reconstructing the smooth DC current into a high-frequency AC square wave with adjustable amplitude and frequency.By modulating the pulse width modulation signal in real time, the effective voltage and fundamental frequency of the AC square wave can be continuously varied, thereby forming the high-frequency AC drive signal required to drive the compressor module. Its fundamental frequency can be continuously adjusted within a wide range from low speed to high speed according to the refrigeration demand, which is the physical basis for realizing variable frequency speed control.

[0033] like Figure 1As shown, to ensure the long-term reliable operation of this high-performance but relatively fragile gallium nitride power module under complex operating conditions, active protection and monitoring units are highly integrated within the module. The temperature detection unit typically uses a negative temperature coefficient thermistor or temperature-sensing diode closely attached to or integrated on the gallium nitride device substrate to sense changes in the junction temperature of the power transistor in real time and generate a continuous junction temperature feedback signal. The overcurrent protection unit, through a milliohm-level precision sampling resistor or current transformer, collects the current in the main power circuit in real time. Once the instantaneous current value exceeds a preset safety threshold (e.g., due to load stall or short circuit), the protection circuit will activate within nanoseconds, generating a hard shutdown signal. These two crucial protective feedback signals are transmitted back to the frequency converter control unit of the drive control module in real time. The variable frequency control unit incorporates corresponding protection algorithms. When it receives a junction temperature feedback signal indicating excessively high temperature, it dynamically reduces the carrier frequency or modulation depth of the output pulse width modulation signal to mitigate switching losses and thus aid in cooling. When the temperature reaches the absolute safety limit or an overcurrent shutdown signal is received, it immediately blocks all pulse width modulation outputs, performs a protective shutdown, and uploads the fault code to the main control module via a status communication link. This combination of local rapid protection and global intelligent management constructs a robust safety defense for the gallium nitride power module. Finally, the high-quality, high-frequency AC drive signal generated by the gallium nitride power module is applied to the compressor module. Modern variable frequency refrigerators generally use scroll or rotary compressors driven by brushless DC motors or permanent magnet synchronous motors, which offer advantages such as high efficiency, low noise, and a wide speed range. The motor incorporates high-resolution position sensors, such as Hall sensors or encoders, to continuously detect the precise angular position of the motor rotor and generate a real-time position feedback signal. This signal is crucial for achieving high-performance closed-loop motor control. This position feedback signal is rapidly fed back to the variable frequency control unit of the drive control module. The variable frequency control unit is currently running advanced algorithms such as field-oriented control or direct torque control. These algorithms take the speed command given in the compressor start-stop control signal as the target and the position feedback signal as the actual state. Through complex vector transformations and real-time calculations, they accurately calculate the optimal voltage vector that should be applied to the motor at the current moment, including its magnitude and phase. Subsequently, the algorithm immediately adjusts the parameters of the gallium nitride drive pulse signal it is generating, correcting its pulse width and phase, thereby changing the instantaneous state of the high-frequency AC drive signal output by the gallium nitride power module. This process continues at an extremely high frequency (typically tens of thousands of times per second), forming a dynamic and precise closed-loop control. As a result, the compressor motor can accurately track the speed command with extremely smooth torque, minimal jitter, and maximum efficiency. Whether operating stably at a low speed to maintain temperature or rapidly accelerating to a high speed for rapid cooling, it can respond quickly and transition smoothly.This precise control not only maximizes energy efficiency but also fundamentally reduces mechanical vibration and operating noise caused by torque pulsations and sudden speed changes. This allows the refrigerator to maintain strong cooling capacity while achieving near-silent operation, enhancing user comfort. From the intelligent signal generation of the drive control module to the efficient energy conversion and active protection of the gallium nitride power module, and then to the precise closed-loop execution and status feedback of the compressor module, these three interconnected links form a dynamic, adaptive, and high-performance energy and motion control closed loop. This fully transforms the theoretical advantages of gallium nitride devices into superior user experience and energy efficiency indicators for the entire refrigerator.

[0034] like Figure 2The diagram illustrates an embodiment of the present invention. This embodiment provides a specific application system for a gallium nitride (GaN) device in a variable frequency refrigerator, whose hardware architecture and signal flow clearly reflect the core concept of the invention. The system starts with AC mains input, which first enters a driver board integrating filtering, power factor correction, and DC-DC conversion functions. The AC power passes through a carefully designed electromagnetic compatibility (EMC) filter circuit at the input, which consists of a common-mode inductor, a differential-mode inductor, and a safety capacitor. Its primary task is to filter out conducted interference from the power grid and suppress high-frequency noise generated by the local switching power supply from feeding back to the grid, ensuring that the system meets stringent EMC standards and providing a relatively clean power environment for subsequent circuits. The filtered AC power is then sent to the power factor correction circuit. In this embodiment, the circuit employs a highly efficient active boost topology, driven by a dedicated control chip that operates a high-speed switching transistor. By actively shaping the input current waveform to closely follow the sinusoidal waveform of the input voltage, the system's input power factor is raised to a high level close to 1.0. This not only significantly reduces reactive power loss and improves the utilization rate of the power grid but also reduces harmonic pollution to the grid. The output of the power factor correction circuit is connected to a substantial high-voltage electrolytic capacitor bank. These capacitors together form a stable high-voltage DC bus, acting like an energy reservoir. This smooths the voltage ripple after rectification and provides instantaneous high-current support during sudden changes in compressor load, ensuring the stability of the bus voltage and laying a solid energy foundation for the subsequent inverter stage. The high-voltage DC bus directly supplies power to the subsequent power inverter section and is also connected to an isolated DC-DC converter circuit, typically a flyback or resonant switching power supply. This circuit safely and efficiently converts hundreds of volts of high-voltage DC into a set of isolated low-voltage DC power supplies, such as 12V, 5V, and 3.3V. These low-voltage power supplies specifically power the system's control chips, sensor circuits, and display panels, etc. Through the electrical isolation of the transformer, power ground noise interference to sensitive control circuits is completely blocked. The system's control core consists of a frequency converter control integrated circuit and a higher-level control system. Working together, they achieve intelligent decision-making from temperature sensing to power drive. The variable frequency control integrated circuit (VFC) located on the driver board is the direct generator of compressor drive commands. It is a highly integrated dedicated motor control chip with advanced algorithms such as space vector pulse width modulation (SVM) embedded internally. This chip receives commands from a higher-level control system, containing key parameters such as the compressor's target operating frequency and torque. Based on these commands, the VFC performs real-time calculations, generating six pulse width modulation signals with strictly interlocked timing sequences and sinusoidally varying duty cycles. These signals are the core control pulses driving the gallium nitride (GaN) power switches.Meanwhile, the control system motherboard, located somewhere inside the refrigerator, acts as the "brain." It continuously collects temperature sensor signals distributed in key locations such as the refrigerator compartment, freezer compartment, and evaporator, and compares this real-time temperature data with the target temperature set by the user through the display panel. Through an embedded adaptive control algorithm, the main control board accurately calculates the required cooling capacity and converts it into specific compressor speed commands, which are then sent to the inverter control integrated circuit on the drive board via communication lines, thus forming a closed-loop temperature control outer loop. The display panel, as the human-machine interface, not only receives user operations such as temperature settings and mode selections but also intuitively displays real-time temperature, operating status, and fault alarm information provided by the control system motherboard, forming a complete information input and feedback channel.

[0035] Furthermore, the most innovative part of this embodiment lies in the power execution unit, namely the inverter bridge arm and drive circuit composed of gallium nitride (GaN) metal-oxide-semiconductor (MOSFET) field-effect transistors. The six pulse-width modulation (PWM) signals generated by the frequency conversion control integrated circuit are first fed into dedicated GaN gate driver chips. Due to the extremely high switching speed and unique drive requirements of GaN devices, traditional drive schemes are no longer applicable. These dedicated driver chips can provide precise negative voltage turn-off, rapid level transitions, and powerful instantaneous drive current, ensuring that each GaN transistor can be quickly and reliably turned on and off at the optimal time. The driven signals are finally applied to the gates of the six GaN transistors in the three-phase full-bridge inverter circuit. In this embodiment, these GaN devices are compactly arranged on the driver board, and thanks to their superior high-frequency characteristics, they can switch at speeds far exceeding those of traditional silicon devices. Under the control of precise timing pulses, the three bridge arms "cut" and reconstruct the high-voltage DC bus voltage into a three-phase symmetrical high-frequency AC current with adjustable amplitude and frequency. This ultimately drives the three-phase AC drive signal for the compressor's brushless DC motor or permanent magnet synchronous motor. The extremely low on-resistance and near-zero switching losses of gallium nitride (GaN) devices are fully utilized here, significantly improving the efficiency of the inverter stage and greatly reducing heat generation. This allows for the use of smaller heat sinks, contributing to the miniaturization and weight reduction of the overall drive board. Furthermore, the drive board integrates a precise current sampling circuit and temperature monitoring point to monitor the output current of the inverter bridge arms and the case temperature of the GaN devices in real time. Once overcurrent or overheating is detected, the protection circuit immediately activates, feeding back the fault signal to the frequency converter control integrated circuit and the main control system, achieving millisecond-level rapid protection and greatly enhancing system reliability.

[0036] like Figure 1As shown, the high-efficiency, high-precision three-phase AC drive signal generated by the gallium nitride inverter bridge is transmitted to the compressor through a reliable electrical connection. This compressor uses a high-performance permanent magnet synchronous motor with an embedded position sensor that feeds back the real-time rotor position signal to the inverter control integrated circuit on the drive board, thus forming a complete inner loop of motor closed-loop control. This inner loop, combined with the aforementioned outer loop of temperature control, forms a dual closed-loop control system. In the inner loop, the inverter control integrated circuit corrects the phase and amplitude of the pulse width modulation signal in real time based on position feedback and speed commands, ensuring the motor operates smoothly with minimal torque pulsation and maximum efficiency, achieving precise control whether maintaining a constant temperature at low speed or rapidly cooling at high speed. In the outer loop, the main control system dynamically adjusts the speed command based on temperature deviation, ensuring a perfect match between cooling capacity and heat load. The entire workflow begins with user settings, is achieved through intelligent decision-making and efficient energy conversion, and culminates in precise execution. When the internal temperature of the refrigerator drops to the set value, the main control system issues a stop command, and the inverter control integrated circuit initiates a soft-stop program, smoothly reducing the compressor speed to a stop, avoiding pressure shocks and noise caused by sudden shutdown. In summary, this embodiment, by deeply integrating gallium nitride devices with an optimized filtering, correction, and control architecture, constructs a high-efficiency, low-noise, and highly reliable variable frequency drive solution from AC input to mechanical output. This fully verifies the significant technological advancements and practical value of this invention in improving refrigerator energy efficiency, noise levels, and control precision.

[0037] This invention provides a gallium nitride (GaN) device application system for variable frequency refrigerators, which solves the problem by reconstructing the compressor drive architecture with GaN power devices as the core. The system first uses a user interaction module to set the temperature and generate a target signal; the main control module compares the real-time temperature and generates a start / stop control signal; the drive control module receives this signal and, through its internal power factor correction, DC-DC conversion, and frequency conversion control unit, generates a dedicated GaN drive pulse signal; the GaN power module, based on this pulse signal, rapidly and precisely controls the switching on and off of multiple GaN devices, generating a high-frequency AC drive signal; finally, the compressor module achieves stepless and smooth variable speed operation based on this high-frequency signal. The entire solution utilizes the high switching frequency and low conduction loss characteristics of GaN devices, combined with a closed-loop link from temperature control to drive, to achieve rapid and precise temperature regulation, higher energy efficiency, and lower operating noise.

[0038] Therefore, the gallium nitride device application system for variable frequency refrigerators provided by the present invention can solve the problems of low system efficiency, slow temperature control response and high operating noise caused by the use of silicon-based power devices in traditional variable frequency refrigerators.

[0039] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A gallium nitride device application system suitable for variable frequency refrigerators, characterized in that, Comprise: a user interaction module that receives a user's temperature setting input and generates a target temperature setting signal; a main control module that receives the target temperature setting signal and receives a real-time temperature sampling signal from a temperature sensor, generates a compressor start-stop control signal by comparing the real-time temperature with the set temperature; a drive control module that receives the compressor start-stop control signal and generates a gallium nitride drive pulse signal based on the signal, wherein the drive control module is integrated with a PFC circuit, a DC / DC conversion unit and a frequency conversion control unit to achieve power factor correction, DC conversion and frequency conversion control of the input power supply; a gallium nitride power module that receives the gallium nitride drive pulse signal and controls the on-off state of a plurality of gallium nitride MOS devices based on the signal to generate a high-frequency AC drive signal; a compressor module that receives the high-frequency AC drive signal and operates at a variable speed based on the high-frequency AC drive signal; wherein the user interaction module, the main control module, the drive control module, the gallium nitride power module and the compressor module are connected in sequence.

2. A system suitable for GaN device applications in a variable frequency refrigerator according to claim 1, wherein, The user interaction module includes an input unit for receiving user touch or key operation and a display unit for displaying the refrigerator running state and set parameters, the input unit converts the user's temperature setting operation into a digital instruction and generates the target temperature setting signal, and the display unit receives the running state feedback signal from the main control module and displays the current temperature, set temperature and compressor working state in real time, the user interaction module is connected with the main control module through an isolation communication line to ensure the electrical isolation between the weak current control signal and the strong current drive part, and improve the system anti-interference ability and human-computer interaction safety.

3. The system of claim 1, wherein the system is adapted for use in a variable frequency refrigerator GaN device application system. The main control module includes a microprocessor unit and a signal conditioning circuit, the signal conditioning circuit filters and amplifies the analog voltage signals collected from a plurality of distributed temperature sensors, converts them into real-time temperature sampling signals and transmits them to the microprocessor unit, the microprocessor unit has a pre-stored temperature control algorithm, which dynamically generates the compressor start-stop control signal containing start, speed regulation and stop instructions by periodically comparing the numerical difference between the real-time temperature sampling signal and the target temperature setting signal, and the signal is further transmitted to the drive control module after electrical isolation by an optoelectronic coupler.

4. The system of claim 1, wherein the system is adapted for use in a variable frequency refrigerator GaN device application system. The power factor correction circuit in the drive control module adopts an interleaved parallel topology to improve the harmonic suppression and power factor compensation effect of the AC input power supply, and the output end is connected with a high-voltage electrolytic capacitor to stabilize the DC bus voltage; the DC conversion unit is an isolated resonant converter for converting the corrected and filtered high-voltage DC into low-voltage DC suitable for subsequent control; the frequency conversion control unit is a core control chip that generates a pulse width modulation signal with variable duty cycle and variable frequency as the gallium nitride drive pulse signal according to the frequency instruction inside the compressor start-stop control signal.

5. The system of claim 1, wherein the system is adapted for use in a variable frequency refrigerator GaN device application system. The gallium nitride power module comprises a driving chip, a gate drive circuit and a plurality of gallium nitride metal oxide semiconductor field effect transistors in a full-bridge or half-bridge structure, the driving chip receives the gallium nitride driving pulse signal and performs level conversion and current amplification, and then generates a driving voltage meeting the fast switching requirement of the gallium nitride device through the gate drive circuit, so as to accurately control the on and off timing of each gallium nitride transistor, thereby inverting the direct current into the high-frequency alternating current driving signal with adjustable amplitude and frequency, and the fundamental frequency of the signal continuously changes in a preset range according to the compressor speed regulation requirement.

6. The system of claim 1, wherein the system is adapted for use in a variable frequency refrigerator GaN device application system. The gallium nitride power module further comprises a temperature detection unit and an overcurrent protection unit integrated thereon, the temperature detection unit monitors the junction temperature of the gallium nitride metal oxide semiconductor field effect transistor in real time and generates a junction temperature feedback signal transmitted to the driving control module, the overcurrent protection unit collects the power loop current in real time through a sampling resistor and generates an off signal when the current exceeds a preset threshold, and the frequency conversion control unit of the driving control module can receive the junction temperature feedback signal and the off signal in real time, and dynamically adjust the parameters of the gallium nitride driving pulse signal or perform protective shutdown according to the signals, so as to prevent the gallium nitride device from being damaged due to overheating or overcurrent.

7. The system of claim 1, wherein the system is adapted for use in a variable frequency refrigerator GaN device application system. The compressor module is a scroll or rotary compressor driven by a brushless direct current motor or a permanent magnet synchronous motor, and a position sensor is embedded in the compressor module for detecting the motor rotor position in real time and generating a position feedback signal, the position feedback signal is fed back to the frequency conversion control unit of the driving control module, the frequency conversion control unit combines the speed instruction in the compressor start-stop control signal and the position feedback signal, and adopts a field-oriented control or direct torque control algorithm to correct the phase and frequency of the gallium nitride driving pulse signal in real time, so as to realize smooth adjustment of the compressor speed and efficient and stable operation of the compressor.

8. The system of claim 1, wherein the system is adapted for use in a GaN device application system of a variable frequency refrigerator. The system further comprises a system power supply unit connected between the user interaction module, the main control module and the driving control module, the system power supply unit takes power from an alternating current input power supply, and sequentially performs electromagnetic compatibility filtering, rectification and multi-channel isolated direct current conversion steps, respectively provides a first low-voltage direct current power supply for the user interaction module, a second low-voltage direct current power supply for the main control module and its attached sensors, and a third low-voltage direct current power supply for the control chip in the driving control module, and the power supplies are electrically isolated through an isolation transformer or an isolation power supply chip, thereby ensuring the stability and safety of the control system.

9. The system of claim 1, wherein the system is suitable for use in a variable frequency refrigerator GaN device application system. A bidirectional state communication link is further established between the main control module and the driving control module, the main control module sends the compressor start-stop control signal to the driving control module, the driving control module feeds back a driving state signal including the direct current bus voltage value, the power module temperature, the output current value and the fault code to the main control module in real time, a state monitoring logic is provided in the main control module, which can analyze the driving state signal and issue a warning information through the user interaction module when an abnormality is judged, and simultaneously adjusts or stops sending the compressor start-stop control signal according to a preset strategy.

10. The system of claim 1, wherein the system is suitable for use in a variable frequency refrigerator GaN device application system. The temperature control algorithm executed by the master module is an adaptive fuzzy proportional integral differential algorithm, which dynamically calculates and outputs a compressor target rotating speed instruction according to the difference between a real-time temperature sampling signal and a target temperature setting signal and the change rate thereof, the target rotating speed instruction being encoded in the compressor start-stop control signal, so that the system can nonlinearly and smoothly adjust the compressor operating frequency according to the change of the internal heat load of the refrigerator, thereby achieving accurate temperature control while minimizing the frequent start-stop and rotating speed mutation of the compressor, improving the energy efficiency and reducing the operating noise.

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