Four-tube parallel bare core integrated three-phase full-bridge inverter power device

Abstract

The invention discloses a three-phase full-bridge inverter power device integrated by four tubes connected in parallel and bare cores, and belongs to the technical field of power electronic power modules. The device comprises a ceramic substrate, a three-phase full-bridge inverter circuit, a current sampling circuit and a secondary step-down power supply circuit, the three-phase full-bridge inverter circuit is composed of six power switch modules; the current sampling circuit is integrated on a lower bridge arm and provides an over-current protection interface; and the secondary step-down power supply circuit realizes single power supply. The current capacity and the power density are improved through the four-tube parallel connection and 2 * 2 arrangement design, the problems that in the prior art, current is insufficient, heat dissipation is poor, the size is large, and power supply is complex are solved, and the device is suitable for long-time operation scenes under severe working conditions.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of power electronic power modules, in particular to a three-phase full-bridge inverter power device with four-gate parallel bare chip integration. BACKGROUND

[0002] The motor driver is the core equipment to realize the speed and direction control of the motor. The three-phase full-bridge inverter circuit inside the motor driver as the core unit of power transmission is called the "power heart" and directly determines the upper limit of the performance of the driver. With the increasing requirements of industrial equipment, aerospace and other fields on the motor driver, the power module is required to have the following key characteristics: high power density to meet the small installation requirements, large current capacity to drive the stable operation of the medium voltage motor, strong heat dissipation capacity to cope with the thermal stress when working at large current, and long-term reliability to meet the continuous operation requirements under severe working conditions. Especially for the open-loop controlled motor driver, the fast response characteristics further aggravate the current / thermal stress of the power module, and higher challenges are put forward to the comprehensive performance of the module. The existing technology has explored the packaging and integration of the power module, but there are still the following significant deficiencies:

[0003] (1) Insufficient current capacity: some solutions use single tube or single chip design, even if multiple tubes are used in parallel, the arrangement of the bare chips leads to uneven current distribution, which cannot effectively expand the rated current and power capacity of the module, and it is difficult to meet the large current demand of the medium voltage motor driver;

[0004] (2) Contradiction between heat dissipation and volume: the traditional plastic packaging or the solution using DBC substrate has large thermal resistance and limited heat dissipation capacity, and when pursuing large current capacity, the volume of the module increases, which cannot balance the miniaturization and high heat dissipation performance;

[0005] (3) Lack of integrated protection mechanism: most power modules do not integrate current sampling function, the control end cannot detect the working current of the module in real time, it is difficult to realize overcurrent protection, and the running safety of the motor driving system is reduced;

[0006] (4) Insufficient reliability: the existing solution has less consideration for the long-term reliability of the power module and the substrate, especially under severe working conditions, the selection of the substrate material and the arrangement of the bare chips lead to insufficient current carrying capacity and thermal cycle resistance of the module;

[0007] (5) Complex power supply mode: the existing power module does not integrate the step-down power supply circuit, the driving module needs to introduce an additional control power supply, which cannot realize single power supply, increases the wiring complexity and cost of the system. SUMMARY

[0008] To solve the above technical problems, the embodiment of the present disclosure provides a four-parallel-die integrated three-phase full-bridge inverter power device. The four-parallel-die design of each bridge arm 4 MOSFET dies greatly expands the rated current and power capacity of the power module. The combination of the thick-film die integration process and the AMB substrate reduces the module volume while improving the power density, meeting the miniaturization installation requirements.

[0009] In a first aspect, the embodiment of the present disclosure provides a four-parallel-die integrated three-phase full-bridge inverter power device, which comprises a three-phase full-bridge inverter circuit, a current sampling circuit, a secondary voltage reduction power supply circuit, and an AMB ceramic substrate.

[0010] The three-phase full-bridge inverter circuit is composed of six power switch modules with the same structure, forming A, B, and C three-phase bridge arms.

[0011] The AMB ceramic substrate is a physical carrier and structural fixing carrier for MOSFET dies of the three-phase full-bridge inverter circuit, sampling resistors of the current sampling circuit, and various components of the secondary voltage reduction power supply circuit. High integration and miniaturization are achieved through zoned and regular layout, and low-impedance electrical connection channels are provided through copper wiring.

[0012] The current sampling circuit is composed of three parallel sampling resistors.

[0013] The secondary voltage reduction power supply circuit shares the input power supply with the three-phase full-bridge inverter circuit, reduces the input power supply to the required low-voltage supply voltage at the control end, and outputs through independent terminals.

[0014] In some embodiments of the present disclosure, the four dies are arranged in a matrix and connected in parallel, forming a four-parallel-die structure.

[0015] In some embodiments of the present disclosure, the three-phase full-bridge inverter circuit does not contain a driving resistor.

[0016] In some embodiments of the present disclosure, the current sampling circuit is respectively connected to the three-phase lower bridge arm power switch modules. By detecting the current flowing through each phase lower bridge arm module, the working current of the whole phase is indirectly obtained, and the three-phase current is monitored and protected.

[0017] In some embodiments of the present disclosure, the current sampling circuit is composed of three sampling resistors with the same structure and parameters. The independent configuration mode of one phase one resistor is adopted. The first one corresponds to the A-phase lower bridge arm, the second one corresponds to the B-phase lower bridge arm, and the third one corresponds to the C-phase lower bridge arm, ensuring independent detection and mutual non-interference of the three-phase current.

[0018] In some embodiments of the present disclosure, each phase bridge arm includes an upper bridge arm power switch module and a lower bridge arm power switch module.

[0019] In some embodiments of the present disclosure, four silicon-based MOSFET bare chips are built in each power switch module.

[0020] In some embodiments of the present disclosure, the secondary voltage reduction power supply circuit is composed of four types of core components, including rectifier diodes, voltage dividing resistors, filter capacitors, and voltage stabilizing tubes. All components are selected from power devices with strong temperature resistance and suitable for thick film integrated technology.

[0021] In some embodiments of the present disclosure, the power supply end of the upper bridge arm power switch module is specially connected to the positive pole of the direct current power supply, and the output end is connected to the output end of the lower bridge arm module in the same group to control the inflow of the positive pole current.

[0022] In some embodiments of the present disclosure, the power supply end of the lower bridge arm power switch module is specially connected to the negative pole of the direct current power supply, and the output end is connected to the output end of the upper bridge arm module in the same group to control the inflow of the negative pole current.

[0023] The present disclosure provides a three-phase full-bridge inverter power device with four parallel bare chips, and the technical solutions provided by the embodiments of the present disclosure at least bring the following beneficial effects:

[0024] (1) The current capacity and power density are significantly improved. Through the design of parallel connection of four MOSFET bare chips in each bridge arm (2x2 matrix arrangement), compared with the single tube or 4x1 arrangement scheme, the current distribution and parasitic inductance loop are effectively optimized, and the rated current and power capacity of the power module are greatly expanded. At the same time, the combination of thick film bare chip integrated technology and AMB substrate not only reduces the module volume but also improves the power density, meeting the miniaturization installation demand.

[0025] (2) Excellent heat dissipation performance. The low thermal resistance characteristic of the AMB ceramic substrate and the direct welding process of the bare chip reduce the heat loss on the heat transfer path, can quickly conduct the heat generated during large current work, solve the heat dissipation problem of the medium voltage motor driver under large current stress, and improve the working stability and service life of the module.

[0026] (3) High operation safety. The integrated current sampling circuit provides a real-time current detection interface for the control end, realizes accurate overcurrent protection, and avoids damage to the module due to overload; the design of independent grid signal extraction facilitates flexible configuration of the driving circuit on the control side, further improving the safety and flexibility of system control.

[0027] (4) The wiring is simple and reliable, the integration of the secondary voltage reduction power supply circuit realizes single power supply of the module, and additional control power supply is not required, which simplifies the power supply design and wiring complexity of the system and reduces the system cost; the high reliability of the AMB substrate and the structural stability of the 2x2 bare chip arrangement enable the module to adapt to long-time operation requirements in harsh working conditions such as aerospace, and the current-carrying capacity and thermal cycle resistance are significantly better than those of the prior art.

[0028] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and are not limiting to the present application. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure or the prior art, the drawings required to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 It is a schematic diagram of the circuit principle of the three-phase full-bridge inverter power device.

[0031] Figure 2 It is a schematic diagram of the circuit layout of the three-phase full-bridge inverter power device. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present disclosure more clear, the present disclosure will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and do not limit the present disclosure.

[0033] Before the technical solutions of the present disclosure are described in detail, the technical background and technical terms involved in the technical solutions are described:

[0034] AMB (Active Metal Brazing, active metal brazing): an advanced connection process specially used to realize the metallurgical combination of ceramics and metals, and its core product (AMB ceramic substrate) is widely used in power electronic power modules as a core bearing and heat dissipation component.

[0035] DBC (Direct Bonded Copper, direct bonded copper substrate): an electric power electronic packaging substrate that realizes the direct combination of ceramic substrate and copper layer through high-temperature diffusion process, which is widely used in power modules with medium and low power density as a core component for bearing power components, conducting current and dissipating heat.

[0036] The three-phase full-bridge inverter power device provided by this invention is suitable for three-phase DC brushless motor drivers. Figure 1 This is a schematic diagram of the circuit principle of a three-phase full-bridge inverter power device.

[0037] The power device includes a three-phase full-bridge inverter circuit, a current sampling circuit, a secondary step-down power supply circuit, and an AMB ceramic substrate.

[0038] The three-phase full-bridge inverter circuit consists of six identical power switch modules, forming three-phase bridge arms A, B, and C. Each phase bridge arm includes an upper bridge arm power switch module and a lower bridge arm power switch module. Each power switch module has four silicon-based MOSFET bare cores. The four bare cores are arranged in a matrix and connected in parallel to form a four-tube parallel structure. The three-phase full-bridge inverter circuit does not contain a drive resistor.

[0039] The AMB ceramic substrate serves as the physical carrier and structural fixation carrier for the bare MOSFET cores of the three-phase full-bridge inverter circuit, the sampling resistors of the current sampling circuit, and various components of the secondary step-down power supply circuit. It achieves high integration and miniaturization through partitioned and orderly layout, and provides low-impedance electrical connection channels through copper-clad wiring.

[0040] The current sampling circuit consists of three parallel sampling resistors, which are respectively connected to the lower arm power switch modules of the three phases. By detecting the current flowing through the lower arm module of each phase, the overall operating current of that phase is indirectly obtained, thereby realizing separate monitoring and overcurrent protection of the three phase currents.

[0041] The secondary step-down power supply circuit shares the input power supply with the three-phase full-bridge inverter circuit, stepping down the input power supply to the low-voltage supply required by the control terminal, and outputting it through an independent terminal.

[0042] The following is a detailed introduction to each of the above components:

[0043] Component 1: Three-phase full-bridge inverter circuit

[0044] The core function of a three-phase full-bridge inverter circuit is to convert the input DC power (such as battery or DC bus power) into three-phase AC power, ultimately driving a three-phase brushless DC motor (controlling speed and direction). It's called a full-bridge inverter in contrast to a half-bridge inverter. A full-bridge inverter achieves complete current commutation and voltage regulation. The three phases correspond to the motor's A, B, and C windings, requiring three sets of AC power with a 120° phase difference to drive the motor. In the aforementioned three-phase full-bridge inverter circuit, six four-transistor parallel power switching modules are arranged in pairs to form independent bridge arms for phases A, B, and C. The two parallel power switching modules in each group serve as the upper bridge arm connected to the positive terminal and the lower bridge arm connected to the negative terminal, respectively. Through the 120° phase difference between the three phases and the complementary conduction of the upper and lower bridge arms, the DC power is inverted into three-phase AC power, ultimately driving the motor to operate smoothly. This design also meets the core requirements of high current, strong heat dissipation, and high integration. A detailed explanation follows:

[0045] (1) Basic unit: 6 power switch modules with the same structure

[0046] These six power switching modules are the basic units of the entire three-phase full-bridge inverter circuit, such as... Figure 1 As shown. The identical structure is not simply a matter of identical appearance, but rather a complete uniformity from internal components and electrical interfaces to process packaging. Each power switch module is designed to precisely meet the core requirements of high current, strong heat dissipation, and high integration. Specific functions and details are as follows:

[0047] Consistency and functionality of internal structure: Each power switch module incorporates four 250V silicon MOSFET (Si MOSFET) bare cores. These four bare cores are not randomly arranged, but rather connected in a 2×2 matrix parallel connection. Compared to the existing 4×1 arrangement, this arrangement optimizes current distribution, reduces parasitic inductance loops, and allows the four bare cores to evenly distribute the current, preventing damage to a single bare core due to current concentration and overload. The source and drain of the four bare cores are shorted using a thick-film printing process to ensure synchronous current conduction and turn-off, while the gate is independently led out, providing a basis for flexible configuration of drive signals at the control end.

[0048] Standardization of electrical interfaces: Each power switch module has three types of fixed interfaces to ensure compatibility with the overall circuit. First, the power supply terminal, used to connect to the positive or negative terminal of the DC bus to provide operating power to the power switch module; second, the output terminal, used to connect to the intermediate node of the bridge arm to transfer the conduction current of the power switch module to the corresponding phase winding of the motor; and third, the gate control terminal, used to receive drive signals from the control chip (such as an MCU or driver chip) to control the turn-on and turn-off timing of the power switch module.

[0049] Uniformity of process packaging: All six power switch modules are soldered to a predetermined area on an AMB (Active Metal Brazing) ceramic substrate using a thick-film bare-core integration process. The low thermal resistance of the AMB substrate ensures heat dissipation for the modules, while the standardized soldering positions allow the six modules to be evenly distributed on the substrate, avoiding local heat accumulation and further improving the stability of module operation.

[0050] This standardized modular design reduces process complexity and production costs, facilitating mass production and subsequent maintenance and replacement. On the other hand, it ensures that the current carrying capacity, conduction characteristics, and heat dissipation efficiency of the six modules are completely consistent, making the working state of the three-phase bridge arm symmetrical and balanced, avoiding the imbalance of three-phase current caused by differences in module performance, which in turn affects the stability of motor operation.

[0051] (2) Functional grouping: A, B, C three-phase bridge arms

[0052] The six standardized power switch modules are divided into three groups of two, namely A, B, and C. Each group constitutes an independent bridge arm for one phase. These three bridge arms are the core functional carriers for realizing three-phase inversion. Their specific functions and details are as follows:

[0053] Grouping logic and connection relationship: Each bridge arm corresponds to a winding of a three-phase brushless DC motor (A-phase bridge arm corresponds to the A-phase winding of the motor, B-phase bridge arm corresponds to the B-phase winding of the motor, and C-phase bridge arm corresponds to the C-phase winding of the motor). The two module output terminals of each bridge arm converge at an intermediate node, which is directly connected to the winding terminal of the corresponding phase of the motor to form a dedicated current channel between the module group and the motor winding, ensuring that the three-phase current does not interfere with each other and is transmitted independently.

[0054] Core Function: The core function of each phase bridge arm is to convert the electrical energy from the DC power supply into the AC power of the corresponding phase and output it to the motor windings. Since the smooth rotation of a three-phase brushless DC motor depends on three sets of AC currents with a strict phase difference of 120°, the A, B, and C phase bridge arms need to output AC currents with phases successively lagging by 120° under the drive of control signals. This phase difference can form a continuously rotating magnetic field inside the motor, thereby driving the motor rotor to rotate stably. This is the purpose of the three-phase design.

[0055] The design of three independent bridge arms is suitable for applications that drive three-phase brushless DC motors. Each bridge arm consists of two power switching modules, which provides a structural basis for the complementary operation of the upper and lower bridge arms and doubles the current carrying capacity of each phase bridge arm, adapting to the high current drive requirements of medium-voltage motors.

[0056] (3) Internal structure of the power switch module: the upper bridge arm power switch module and the lower bridge arm power switch module

[0057] Although the two power switching modules in each phase arm have identical structures, their connection positions and functional divisions in the circuit are completely different. They form a complementary and synergistic relationship, working together to generate and regulate the AC power of the corresponding phase. Their specific functions and details are as follows:

[0058] Connection and function of the upper arm power switch module: The power supply terminal of the upper arm power switch module is specifically connected to the positive terminal (P terminal) of the DC power supply. The output terminal and the output terminal of the lower arm module in the same group are connected to the same intermediate node (i.e., the node connecting the corresponding phase winding of the motor). Its function is to control the inflow of positive current. When the control signal triggers the module to conduct, the current of the positive terminal of the DC power supply will flow through the module to the intermediate node, and then flow into the corresponding phase winding of the motor to provide driving power for the motor. When the module is turned off, the path of positive current is cut off, and the power supply to the phase winding stops.

[0059] Connection and function of the lower bridge arm power switch module: The power supply terminal of the lower bridge arm power switch module is specifically connected to the negative terminal (GND) of the DC power supply, and its output terminal is also connected to the output terminal of the upper bridge arm module at the same intermediate node. Its function is twofold: first, to control the return current of the negative terminal. When this module is turned on, the current in the corresponding phase winding of the motor will flow into this module through the intermediate node and eventually return to the negative terminal of the DC power supply, forming a complete current loop; second, to coordinate with the upper bridge arm to adjust the output voltage. By alternating the conduction of the lower bridge arm module with the upper bridge arm module, the duration of the current in the winding is changed, thereby adjusting the amplitude of the output voltage.

[0060] In terms of operational logic, the upper and lower bridge arm power switch modules have strictly complementary operating timings and must never be turned on simultaneously. If both are turned on at the same time, a direct short circuit loop will be formed between the positive terminal of the DC power supply, the upper bridge arm module, the lower bridge arm module, and the negative terminal of the DC power supply, instantly generating an extremely large current and burning out the modules and the power supply. The circuit design of this invention does not contain drive resistors; therefore, this short-circuit protection relies entirely on the precise timing control of the control signals. Simultaneously, by adjusting the on-time ratio of the two modules (i.e., PWM pulse width modulation), the effective value of the output voltage of that phase can be changed, thereby regulating the motor speed. A higher on-time ratio results in a larger output voltage and a faster motor speed; conversely, a lower on-time ratio results in a slower speed.

[0061] Component 2: AMB ceramic substrate

[0062] The AMB ceramic substrate is the core carrier and performance guarantee of the thick-film bare-die integration process for the power module of this invention. Its design and application directly determine the current carrying capacity, heat dissipation efficiency, and long-term operational reliability of the power module. As a dedicated mounting substrate for all MOSFET bare dies, the AMB ceramic substrate achieves stable fixation of all MOSFET bare dies through the synergistic cooperation of the thick-film bare-die integration process and the welding process. During the process, the bare dies are precisely positioned and welded to a preset area on the substrate surface. The welding nodes are tight and firm, providing stable mechanical support for the bare dies and constructing an efficient electrical connection and heat conduction channel. This ensures that the bare dies will not experience displacement or poor contact under high current operating conditions, laying the foundation for the structural integrity of the power module. Compared with traditional DBC substrates and aluminum substrates, the AMB ceramic substrate has three core performance advantages, and these advantages precisely match the application requirements of the power module of this invention.

[0063] The AMB ceramic substrate and the three-phase full-bridge inverter circuit, current sampling circuit, and secondary step-down power supply circuit are not simply in a carrier-carrying relationship, but rather a mutually compatible one. The substrate provides the foundation for the performance guarantee of these three circuits, and the functional requirements of these three circuits in turn determine the design parameters of the substrate, as detailed below:

[0064] The three-phase full-bridge inverter circuit is the power core of the module. Its high current, high heat generation, and symmetrical operation characteristics are precisely matched with the performance of the AMB substrate. The six power switching modules (each module has four bare MOSFETs) of the three-phase full-bridge inverter circuit are arranged on the AMB substrate in an "A / B / C three-phase bridge arm" configuration. The upper and lower bridge arm modules of each phase are symmetrically distributed. The four bare MOSFETs in each module are soldered in a 2×2 matrix. The size of the AMB substrate and its copper plating layout perfectly match this structure, ensuring balanced current paths for each module and avoiding localized current concentration. The "four-MOSFET parallel" design of the three-phase full-bridge inverter circuit needs to handle ultra-high current, and the thickened copper plating layer (≥0.5mm) and strong current-carrying capacity of the AMB substrate provide sufficient current for each phase. The eight bare MOSFETs in the bridge arm (four in each of the upper and lower arms) provide a stable current transmission path, preventing overheating or malfunctions caused by insufficient current carrying capacity. The three-phase full-bridge inverter circuit is the main heat source of the module (24 bare MOSFETs working simultaneously). The low thermal resistance of the AMB substrate is key to heat dissipation. The heat generated by the bare MOSFETs is directly conducted to the substrate through the soldering interface and then quickly diffused, ensuring that the operating temperature of each bare MOSFET is controlled within a safe range, avoiding performance degradation of the bare MOSFETs due to thermal stress, and ensuring symmetrical operation of the three-phase bridge arms (temperature balance to avoid three-phase current imbalance).

[0065] The current sampling circuit is the core of the module's safety monitoring, and its accurate detection requirements also rely on the support of the AMB substrate. The three parallel sampling resistors of the current sampling circuit are fixed to a predetermined area under the AMB substrate by welding. The flat surface of the substrate and the robust welding process ensure a low-impedance, secure electrical connection between the sampling resistors and the source terminals of the lower arms of the three-phase full-bridge, avoiding sampling errors caused by changes in contact resistance and ensuring the accuracy of current detection. The sampling resistors generate heat during operation; if the temperature is too high, the resistance value will drift, affecting sampling accuracy. The AMB substrate's efficient heat dissipation capability quickly dissipates the heat from the sampling resistors, maintaining a stable operating temperature and preventing overcurrent protection threshold deviations due to temperature drift, ensuring the control terminal can accurately identify the module's operating current. The partitioned layout design of the AMB substrate centrally arranges the sampling resistors under the three-phase full-bridge, isolating them from the secondary step-down power supply circuit. Simultaneously, the ceramic substrate of the substrate has insulating properties, preventing electromagnetic interference from the large current signal of the three-phase full-bridge to the sampling circuit, ensuring the purity of the sampling signal.

[0066] The secondary buck power supply circuit is the core of the module's single-power supply, and its safe voltage reduction requirement is critically guaranteed by the AMB substrate. All components of the secondary buck power supply circuit (diodes D1~D3, resistors R4~R6, capacitor C10, and Zener diode M7) are integrated and soldered in a separate area on the right side of the AMB substrate. The compact layout design of the substrate achieves the integrated integration of the buck circuit and the power module without occupying the space of the three-phase full-bridge and sampling circuit, providing a structural foundation for single-power supply. When the secondary buck power supply circuit is working, the resistors and diodes will generate heat. Overheating will lead to a decrease in buck efficiency and output voltage fluctuations. The low-resistance heat dissipation characteristics of the AMB substrate can quickly dissipate this heat, preventing the buck circuit from triggering protection or being damaged due to overheating. This ensures that it can stably step down the high-voltage power supply to the low voltage required by the control terminal (such as 20V), guaranteeing stable power supply to the control terminal. The input side of the secondary buck power supply circuit is connected to the high-voltage power supply, and the output side is connected to the low-voltage control terminal. The ceramic substrate of the AMB substrate has excellent insulation properties, which can achieve electrical isolation between the high-voltage area and the low-voltage area, preventing high-voltage leakage from damaging the control terminal. At the same time, the copper-clad wiring of the substrate provides a low-impedance current transmission path for the buck circuit, reducing voltage loss and ensuring bucking accuracy.

[0067] It is evident that the AMB ceramic substrate is the common basic platform for the three circuits mentioned above. The high integration and high current requirements of these three circuits, in turn, dictate that the substrate must be made of AMB material (rather than DBC / aluminum substrate), and this functionality is achieved through design adaptations such as partitioned layout and thickened copper plating.

[0068] Component 3: Current sampling circuit

[0069] The design of the current sampling circuit revolves around accurately acquiring three-phase current, supporting independent overcurrent protection, and adapting to highly integrated and high-current scenarios. It works in deep collaboration with the three-phase full-bridge inverter circuit and AMB ceramic substrate, and is a key functional unit for achieving safe operation and precise control of the module.

[0070] The core function of this circuit is to detect the operating current of the three-phase bridge arms (A, B, and C) in real time and accurately, providing a clean and reliable current feedback signal to the control terminal. Ultimately, it achieves two main goals: first, to support closed-loop regulation of the three-phase current by the control terminal (such as a current closed-loop algorithm adapted to motor speed control); and second, to trigger overcurrent protection. When the current of one or more phases exceeds the rated threshold, the control terminal can quickly cut off the drive signal of the corresponding bridge arm, preventing the bare core of the MOSFET and the motor winding from burning out due to overload, thus solving the pain point that most power modules do not integrate current sampling function.

[0071] The current sampling circuit consists of three sampling resistors with identical structure and parameters, arranged in an independent configuration of one resistor per phase. The first resistor corresponds to the lower bridge arm of phase A, the second to the lower bridge arm of phase B, and the third to the lower bridge arm of phase C, ensuring independent detection and non-interference of the three-phase currents. The selected resistor must be suitable for the high-current scenario of four transistors in parallel in this invention. For example, a 2W power rating and a 10mΩ resistance alloy sampling resistor should be used (alloy materials have a low temperature coefficient and high stability, which can reduce the impact of temperature drift on sampling accuracy). The power rating design must ensure that it does not overheat or overload when a large current flows through it, and the resistance value selection must balance sampling accuracy (too small a resistance results in a weak signal, while too large a resistance results in energy loss), ultimately achieving a low-loss, high-precision sampling effect.

[0072] The three sampling resistors are connected in parallel (not physically in parallel, but rather each is independently connected to its corresponding phase circuit, with the signal terminals connected in parallel to sum), ensuring that each resistor only detects the operating current of its corresponding phase, avoiding cross-phase interference. Each sampling resistor is connected in series between the source of the power switch module of the corresponding phase's lower bridge arm and the common node of the circuit (power supply negative terminal GND). Since the operating current of each phase needs to flow back to the power supply negative terminal through the lower bridge arm module in this invention, the sampling resistor connected in series here can completely capture the entire operating current of that phase (including the total current of the four transistors in parallel), ensuring that the detection results are complete and without omissions or deviations. The signal output terminals of the three sampling resistors converge to a Vsense signal interface (i.e., voltage sampling terminal), which is independently led out to an external connection terminal at the edge of the module, facilitating direct connection of the control terminal (such as an MCU or ADC sampling chip) via wires without the need for additional wiring modifications. The sampling resistor is physically isolated from the high-current region of the three-phase full-bridge inverter circuit and the high- and low-voltage regions of the secondary step-down power supply circuit through the partitioned layout of the AMB ceramic substrate. Furthermore, the ceramic substrate has excellent insulation properties, which prevents electromagnetic interference from high-current and high-voltage signals on the sampling signal and ensures the purity of the Vsense signal.

[0073] The three sampling resistors of the current sampling circuit are centrally located in the lower region of the AMB ceramic substrate, adjacent to the lower arm power switch module of the three-phase full-bridge inverter circuit. This layout design has three major advantages: First, it shortens the connection path between the sampling resistors and the lower arm module, reducing line impedance and minimizing signal loss and delay. Second, the centralized layout facilitates concentrated heat dissipation, leveraging the efficient heat dissipation capabilities of the AMB substrate to quickly dissipate the small amount of heat generated by the sampling resistors during operation, preventing resistance drift due to excessive temperature. Third, it isolates the circuit from the secondary step-down power supply circuit, further reducing the risk of electromagnetic interference. The sampling resistors are fixed to the pre-set pads on the AMB substrate using a thick-film soldering process. The soldering nodes must meet the requirements of low contact resistance and high mechanical strength. Low contact resistance prevents contact point overheating or signal distortion, while high mechanical strength withstands harsh conditions such as vibration and thermal cycling, ensuring long-term reliability of the circuit connection and full compatibility with the thick-film bare-core integration process of the entire module.

[0074] The working principle of the current sampling circuit will be explained below in the context of an operational scenario:

[0075] (1) Current detection process: When the module is working, the working current of the three-phase bridge arms A, B and C flows back to the negative terminal of the power supply through their respective lower bridge arm power switch modules. During this process, the current will flow through the sampling resistor of the corresponding phase. According to Ohm's law (U=IR), a weak voltage signal proportional to the current will be generated across the sampling resistor (e.g., when 100A current flows through a 10mΩ resistor, a 1V voltage signal will be generated).

[0076] (2) Signal transmission and processing: The three-phase voltage signals generated by the three sampling resistors are synchronously transmitted to the control terminal through the Vsense interface. The ADC (analog-to-digital converter) chip built into the control terminal converts the analog voltage signals into digital signals, and then calculates the real-time operating current of each phase (derived in reverse by the resistance value of the calibration resistor).

[0077] (3) Overcurrent protection action: The control terminal presets the rated threshold of the three-phase current (such as the maximum carrying current of the 250V Si MOSFET) and compares the detected three-phase current value with the threshold in real time. If the current of a certain phase exceeds the threshold, the control terminal will cut off the gate drive signal of the bridge arm of that phase within microseconds, so that both the upper and lower bridge arm modules are turned off, blocking the current path of that phase. If multiple phases are overcurrent at the same time, all bridge arm drive signals will be cut off synchronously until the fault is cleared, maximizing the protection of the module and motor safety.

[0078] (4) Adapting to PWM modulation scenarios: Since the three-phase full-bridge inverter circuit operates in PWM (pulse width modulation) mode, the current has high-frequency pulsation. The low parasitic inductance design of the sampling resistor (alloy material + short lead layout) can avoid high-frequency interference caused by pulsating current, ensuring that the sampling signal can accurately follow the current change and not affect the real-time adjustment accuracy of the control terminal.

[0079] Component 4: Secondary step-down power supply circuit

[0080] The secondary step-down power supply circuit is the core functional unit for achieving single-power supply in the power module of this invention. Its design revolves around four core objectives: high-efficiency step-down, stable power supply, integrated layout, and safe heat dissipation. It works in deep collaboration with the three-phase full-bridge inverter circuit and AMB ceramic substrate to solve the pain point of power modules not integrating step-down power supply and requiring the introduction of an additional control power supply. It provides a clean and reliable low-voltage power supply to the control end and is a key support for achieving high integration and ease of use in the power module.

[0081] The core function of the secondary step-down power supply circuit is to precisely step down the input high-voltage power supply (compatible with the operating voltage of 250V Si MOSFETs) to the low-voltage supply voltage (20V) required by the control terminal (such as gate driver chips and MCUs) through a series of processes including rectification, voltage division, filtering, and voltage regulation, ultimately achieving two core objectives:

[0082] Integrated power supply: It shares the same power input with the three-phase full-bridge inverter circuit, eliminating the need for an additional independent control power supply. This enables the module to be powered by a single power supply, simplifying system wiring and power supply design and reducing user costs.

[0083] Stable and reliable power supply: In the high current and high heat generation module working environment, it maintains the stability of output voltage (small ripple and narrow voltage fluctuation range), while having good heat dissipation capacity to avoid the reduction of step-down efficiency or circuit damage due to overheating, and ensures the continuous and stable operation of the control end.

[0084] The secondary step-down power supply circuit consists of four core components: rectifier diodes, voltage divider resistors, filter capacitors, and Zener diodes. All components are high-temperature resistant power devices adapted to thick-film integrated circuit technology. The circuit's power input terminal is directly connected to the power supply terminal (P terminal, i.e., the positive DC power supply) of the three-phase full-bridge inverter circuit, sharing the same input power supply with the three-phase full-bridge, eliminating the need for an additional independent power supply interface and achieving a single power input structure. The circuit's low-voltage output terminal is independently led out as the control terminal, directly connected to the external connection terminal at the edge of the module, facilitating direct access to the control terminal (gate driver chip, MCU). The output voltage is stable at 20V, meeting the conventional power supply requirements of control components. The circuit's ground terminal (GND) is connected to the module's common ground network, sharing the same ground plane with the three-phase full-bridge inverter circuit and current sampling circuit, ensuring consistent potential across all circuits and avoiding signal interference caused by ground potential differences.

[0085] The circuit is physically isolated from the three-phase full-bridge inverter circuit and the current sampling circuit through the partitioned layout of the AMB ceramic substrate (independently arranged in the right area of ​​the substrate), avoiding electromagnetic interference from the large current and high voltage signals of the three-phase full-bridge to the step-down circuit; relying on the insulating properties of the ceramic substrate of the AMB ceramic substrate, the "high voltage input side" and "low voltage output side" of the step-down circuit are electrically isolated, avoiding damage to the control terminal components caused by high voltage leakage and ensuring power supply safety.

[0086] Figure 2 This is a schematic diagram of the circuit layout of a three-phase full-bridge inverter power device. The main body of the diagram is a rectangular AMB ceramic substrate with mounting holes at the edges (e.g., the four corners) for module mounting. The substrate surface is a thick-film copper-clad circuit area. The MOSFET bare die layout area is distributed on the substrate in six 2×2 matrix arrangements, each group corresponding to four SiMOSFET bare dies (a total of 24 dies) for one arm of the three-phase full-bridge inverter. Each group of bare die areas is connected by copper-clad circuitry on the substrate surface (black traces in the diagram), achieving electrical connection between the source and drain of the bare die, matching the circuit topology of the three-phase full-bridge inverter.

[0087] In practical applications, the selection of components used in three-phase full-bridge inverter power devices is as follows:

[0088] Si MOSFET bare core: Model selected is 250V / 30A specification, 4 chips per bridge arm, 24 chips in total;

[0089] AMB ceramic substrate: The ceramic material is AlN (aluminum nitride), the copper cladding thickness is 0.3mm, and the substrate size is designed to be 50mm×40mm according to the module power requirements;

[0090] Sampling resistor: High-precision alloy sampling resistors are selected, with a resistance of 10mΩ and a power of 2W, and three are set in parallel;

[0091] Secondary step-down circuit components: Resistors R4 and R5 are 100kΩ (power 1 / 4W), R6 is 470Ω (power 1 / 2W); Diode D2 is a 20V Schottky diode, D1 and D3 are ordinary rectifier diodes; Capacitor C10 is a 10uF / 50V ceramic capacitor; MOSFET M7 is an N-channel enhancement-mode MOSFET (20V / 5A).

[0092] The layout and connection of the above components are as follows: 24 SiMOSFET bare cores are divided into 6 groups of 4 cores each, corresponding to 6 bridge arms. Each group of bare cores adopts a 2×2 matrix layout with a spacing of 1.5mm between the cores to ensure uniform heat dissipation and consistent current path. The sampling resistors are arranged in parallel below the full-bridge circuit and soldered to the copper-clad area of ​​the AMB substrate. The two ends of the three resistors are connected in parallel through copper-clad lines, and the Vsense terminal is led out to the module pins. The components of the secondary buck circuit are concentrated on the side of the module. Resistors, diodes, and capacitors are fixed to the substrate through through-hole or surface mount methods. The MOSFET M7 is tightly attached to the copper-clad substrate to improve heat dissipation. The gates of all bare cores are independently led out to the module pins (AL1~AL4, BL1~BL4, CL1~CL4, etc.) to facilitate the control side to configure drive resistors and drive signals according to requirements. The source and drain are connected to the adjacent bridge arms, power supply, and output terminals through copper-clad lines.

[0093] The fabrication of a three-phase full-bridge inverter power unit includes the following aspects:

[0094] AM substrate pretreatment: The AMB ceramic substrate is cleaned and dried to remove surface impurities and ensure welding reliability;

[0095] Component positioning and brazing: The bare Si MOSFET core, sampling resistor, and secondary step-down circuit components are positioned according to the layout diagram, and high-temperature brazing is performed using silver-based solder to form a strong electrical and mechanical connection between the components and the copper-clad substrate.

[0096] Bonding and wiring connection: For fine-pitch pins such as gates in bare dies, gold wire bonding is used to connect them to the copper-clad circuitry on the substrate.

[0097] Testing and Packaging: Perform continuity testing, insulation testing, current-voltage characteristic testing, and heat dissipation testing on the module. After passing the tests, perform surface protection treatment (such as coating with conformal coating) to complete the packaging.

[0098] The above describes the components, hardware circuit layout, component selection, and manufacturing process of the three-phase full-bridge inverter power device. The following describes the workflow of the three-phase full-bridge inverter power device. When the power module is connected to the power supply, the secondary power supply step-down circuit reduces the input voltage to the voltage required by the control terminal (e.g., 12V or 5V) to power the control circuit, achieving single-supply power supply functionality. The control terminal outputs drive signals through independent gate terminals to control the MOSFET bare cores of each bridge arm to turn on or off. The three-phase full-bridge circuit converts DC power to three-phase AC power to drive the three-phase brushless DC motor. During operation, the sampling resistor monitors the current of the lower bridge arm in real time. The control terminal obtains the current signal through the Vsense terminal. When the current exceeds a set threshold, the MOSFET of the corresponding bridge arm is immediately turned off to achieve overcurrent protection. The AMB substrate and thick-film bare core integration process ensure rapid heat dissipation from the module, maintaining the module's operation within a safe temperature range.

[0099] The three-phase full-bridge inverter power device of the present invention was tested, and the results showed that the rated current of the three-phase full-bridge inverter power device can reach 200A, the power density is ≥5W / cm³, the thermal resistance is ≤0.5℃ / W, and there is no performance degradation during long-term operation (1000h). It can be widely used in medium-voltage three-phase DC brushless motor drivers, industrial frequency converters, new energy equipment and other fields.

[0100] It is understood that the same / similar parts between the various embodiments of the methods described above in this specification can be referred to each other. Each embodiment focuses on the differences from other embodiments, and relevant parts can be referred to the description of other method embodiments.

[0101] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this disclosure can be achieved, and this is not limited herein.

[0102] The specific embodiments described above do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A three-phase full-bridge inverter power device with four paralleled bare dies, characterized in that, The device comprises a three-phase full-bridge inverter circuit, a current sampling circuit, a secondary voltage reduction power supply circuit and an AMB ceramic substrate; The three-phase full-bridge inverter circuit is composed of six power switch modules with the same structure, forming A, B and C three-phase bridge arms. The AMB ceramic substrate is a physical carrier and structural fixing carrier of MOSFET bare chips of the three-phase full-bridge inverter circuit, sampling resistors of the current sampling circuit and various components of the secondary voltage reduction power supply circuit, which realizes high integration and miniaturization through partitioned and regular layout, and provides a low-impedance electrical connection channel through copper wiring. The current sampling circuit is composed of three sampling resistors arranged in parallel. The secondary voltage reduction power supply circuit shares the input power supply with the three-phase full-bridge inverter circuit, reduces the input power supply to the low voltage supply voltage required by the control end, and outputs through an independent terminal.

2. The apparatus of claim 1, wherein, The four bare chips are arranged in a matrix and connected in parallel, forming a four-tube parallel structure.

3. The apparatus of claim 1, wherein, The three-phase full-bridge inverter circuit does not contain a driving resistor.

4. The apparatus of claim 1, wherein, The current sampling circuit is connected to the lower bridge arm power switch module of each phase, respectively, indirectly obtains the working current of the whole phase by detecting the current flowing through each lower bridge arm module, and realizes the separate monitoring and overcurrent protection of the three-phase current.

5. The apparatus of claim 4, wherein, The current sampling circuit is composed of three sampling resistors with the same structure and parameters, and adopts an independent configuration mode of one resistor per phase, the first resistor corresponds to the A-phase lower bridge arm, the second resistor corresponds to the B-phase lower bridge arm, and the third resistor corresponds to the C-phase lower bridge arm, ensuring independent detection and mutual non-interference of the three-phase current.

6. The apparatus of claim 1, wherein, Each phase bridge arm comprises an upper bridge arm power switch module and a lower bridge arm power switch module.

7. The apparatus of claim 6, wherein, Each power switch module is built-in four silicon-based MOSFET bare chips.

8. The apparatus of claim 1, wherein, The secondary voltage reduction power supply circuit is composed of four types of core components, i.e. rectifier diodes, voltage dividing resistors, filter capacitors and voltage stabilizing tubes, and all components are selected from power devices with strong temperature resistance and adaptive thick film integrated technology.

9. The apparatus of claim 1, wherein, The power supply end of the upper bridge arm power switch module is specially connected to the positive pole of the direct current power supply, and the output end is connected to the output end of the lower bridge arm module of the same group to control the inflow of the positive pole current.

10. The apparatus of claim 1, wherein, The power supply end of the lower bridge arm power switch module is specially connected to the negative pole of the direct current power supply, and the output end is connected to the output end of the upper bridge arm module of the same group to control the inflow of the positive pole current.

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