A thick-film substrate-based motor driver

Abstract

The application relates to a thick-film substrate-based motor driver and belongs to the technical field of motor driving. The driver adopts a thick-film process to integrate and encapsulate power tube bare chips into a thick-film process power circuit, matches an integrated logic chip GKA4096TSA and a power MOS tube gate drive chip, integrates an optical coupling isolation circuit and a current-limiting protection circuit, and adopts a universalized metal shell encapsulation. The application realizes the driving demand of a 90V, 56V power supply, 1.5kW-2kW three-phase brushless direct-current motor, has the advantages of high integration degree, strong universality, nationalization and miniaturization, and can be widely applied to electric rudders and related equipment.

Description

Technical Field

[0001] This invention relates to the field of motor drive technology, and in particular to a motor driver based on a thick film substrate. Background Technology

[0002] In the field of motor drive technology, three-phase brushless DC motors, with their core advantages of high efficiency and high reliability, have become the core drive components for critical equipment such as electric servos. The performance of their matching drivers directly determines the operational stability and adaptability of the entire system. Especially for applications involving 1.5kW-class electric servos under 90V and 56V power supply systems, the market has placed stringent demands on the miniaturization, integration, versatility, and anti-interference capabilities of the drivers. Currently, there are two main design schemes for drivers of three-phase brushless DC motors in the industry, but both have significant technical defects and are unable to meet the aforementioned application requirements:

[0003] (1) Conventional printed circuit board design schemes use traditional discrete power transistors. Due to the large size of the power transistors themselves, the miniaturization design of the driver faces a significant bottleneck. At the same time, since different system models have different requirements for driver installation space, interface form, etc., the existing printed circuit board design drivers need to be customized for different models, which limits their universality in multi-model systems and makes it impossible to achieve cross-model universal adaptation. This not only increases the R&D and production costs, but also increases the complexity of later maintenance.

[0004] (2) The pure thick film circuit design scheme integrates some devices through thick film technology, but there are many key shortcomings: On the one hand, the integration form of the circuit structure makes signal testing difficult and subsequent parameter adjustment inconvenient. Moreover, once the device is damaged, the replacement and maintenance operation is complicated, which directly leads to an increase in the product scrap rate. On the other hand, its electromagnetic interference shielding design is insufficient, the overall anti-interference capability is weak, it is difficult to cope with the complex electromagnetic environment of electric servo motors and other equipment, and it cannot guarantee the operational stability under high-precision drive scenarios.

[0005] These shortcomings have become urgent technical problems that need to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a motor driver based on a thick-film substrate. It employs thick-film technology to integrate and package bare power transistor chips onto a ceramic substrate. Combined with core components such as the SiP integrated logic chip GKA4096TSA and gate driver chips, the logic calculation, gate driving, and other functional circuits are integrated into a small logic board. All functional circuit boards are then integrated and packaged in a general-purpose housing, ultimately forming an integrated, modular motor driver. This driver reduces the size of the original power circuit while maintaining ease of testing, interference resistance, and general compatibility. The technical solution adopted by this invention is as follows:

[0007] A motor driver based on a thick film substrate, the motor driver adopts a generalized packaging structure, the motor driver includes a thick film process power circuit, an integrated logic control circuit, a power MOSFET gate drive circuit, an optocoupler isolation circuit, a current limiting protection circuit, and a secondary power supply circuit.

[0008] Thick-film power circuits include a three-phase full-bridge inverter circuit, a current sampling circuit, a ceramic substrate, and an aluminum substrate.

[0009] The integrated logic control circuit uses domestically produced SiP integrated chips to perform signal processing, timing control, and safety protection logic triggering functions.

[0010] The gate drive circuit of the power MOSFET adopts a fully domestically produced drive chip, which converts the weak gate control signal output by the integrated logic control circuit into a strong drive signal that can drive the power MOSFET to turn on / off quickly, while realizing high voltage isolation and protection functions.

[0011] Optical isolation circuits are connected in series between the external controller and the integrated logic control circuit for electrical isolation protection and signal fidelity transmission;

[0012] The current limiting protection circuit is connected in series between the power supply input terminal and the thick film process power circuit to monitor the power bus current throughout the entire path. Through linkage with the integrated logic control circuit, it realizes closed-loop protection of detection, judgment and execution.

[0013] The secondary power supply circuit provides a stable and matched operating voltage for each module inside the motor driver.

[0014] Furthermore, the three-phase full-bridge inverter circuit consists of three 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 two silicon-based MOSFET bare cores built in. The two 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.

[0015] Furthermore, the ceramic substrate serves as the physical carrier and structural fixation carrier for the bare MOSFET cores of the three-phase full-bridge inverter circuit and the sampling resistor components of the current sampling circuit. By employing thick-film technology, six bare power transistor chips are directly integrated and packaged on its own surface to form an integrated power MOSFET chip, thereby constituting a three-phase inverter bridge circuit.

[0016] Furthermore, the ceramic substrate integrating the bare power MOSFET chip is directly placed on the surface of the aluminum substrate together with the sampling resistor, forming a composite structure in which the ceramic substrate is attached to the aluminum substrate.

[0017] Furthermore, the general-purpose packaging structure is a three-layer architecture consisting of an outer shell, internal stacked modules, and interface components. It includes a general-purpose metal shell, power board, logic board, connection components, and auxiliary protection components, all of which work together to form an integrated drive module.

[0018] Furthermore, the power board uses an aluminum substrate as the underlying base and a ceramic substrate is fixed on the surface.

[0019] Furthermore, the logic board adopts a six-layer PCB design, with surface-integrated integrated logic control circuit, power MOSFET gate drive circuit, optocoupler isolation circuit, current limiting protection circuit and secondary power supply circuit.

[0020] Furthermore, the power board and logic board adopt an upper and lower stacked welding structure, with the logic board on the upper layer and the power board on the lower layer, and the two boards are positioned by multiple sets of metal support pillars.

[0021] Furthermore, the electrical contacts between the power board and the logic board adopt a hybrid connection method of metal solder pads and copper wires. High current signals are soldered through metal solder pads, while low current signals are bonded through copper wires.

[0022] Furthermore, the general-purpose metal casing adopts a split design of top cover and base, with the base having a recessed structure. The power board and logic board are fixed inside the base by fasteners.

[0023] The technical solutions provided by the embodiments of the present invention bring at least the following beneficial effects:

[0024] (1) High degree of integration: The power transistor bare chip is integrated and packaged using thick film technology, and is paired with integrated logic chip and integrated driver chip to simplify the circuit form, reduce the number of components, and improve system reliability; It adopts a general metal shell package, which can be used for 1kW-2kW level multi-power three-phase brushless DC motor drive, adapt to different system models, and reduce design and maintenance costs.

[0025] (2) Miniaturization and high power density: The volume of the power circuit of the thick film process is reduced by nearly 50% compared with the traditional solution. The low power consumption design of the logic chip and the driver chip further optimizes the system performance and improves the power density. The integrated logic chip has low transmission delay and fast level conversion rate, and the driver chip has high voltage resistance, low delay and strong negative voltage resistance. The overall anti-interference ability and working stability are significantly improved.

[0026] (3) Core components, such as integrated logic chip GKA4096TSA, driver chip, integrated power MOSFET, etc., are all domestically produced, ensuring the supply chain is independent and controllable.

[0027] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0029] Figure 1 This is a schematic diagram of the power MOSFET gate drive circuit.

[0030] Figure 2 This is a schematic diagram of the circuit principle of the RX chip at the receiving end;

[0031] Figure 3 This is a schematic diagram of the circuit principle of the transmitter TX chip;

[0032] Figure 4 This is a schematic diagram of the peripheral circuit of the power MOSFET gate drive circuit. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] Before describing the technical solution of the present invention in detail, the technical background and technical terms involved in the technical solution will be explained first:

[0035] Thick film technology: a substrate-based electronic component integration manufacturing technology. The core of this technology is to prepare functional film layers (conductors, resistors, dielectrics, etc.) with a thickness of several micrometers to tens of micrometers on the surface of an insulating substrate (such as ceramic or alumina substrate) through specific processes, and then integrate and package bare chips, discrete devices, etc. to form high-density, miniaturized electronic functional modules. These modules are widely used in power electronics, automotive electronics, and other fields with stringent requirements for integration, reliability, and heat dissipation.

[0036] Bare Die Packaging: A high-density integrated packaging technology that skips the traditional separate plastic / metal casing packaging of chips. It directly fixes the unpackaged semiconductor die (the core functional layer of the chip, without external protective shells, lead frames, or other packaging structures) onto a target substrate (such as the ceramic substrate in this application) through bonding, soldering, or adhesive bonding. Electrical connections between the bare die and the substrate circuitry are achieved using metal bonding wires, flip-chip bonding, and other processes. Finally, it is integrated with other functional circuits to form a complete module. This technology is widely used in power electronics and other fields with stringent requirements for size, weight, heat dissipation, and integration density.

[0037] Pure Thick-Film Circuit: This electronic circuit technology relies solely on thick-film processes. Its core involves using screen printing, high-temperature sintering, and other thick-film processes to fabricate functional films such as conductors, resistors, and dielectrics on the surface of an insulating substrate (e.g., ceramic or alumina substrate), forming a complete circuit path. Discrete components (chips with traditional packages, resistors, capacitors, etc.) are then directly soldered onto the pads of the thick-film circuit, without the need for other integration technologies such as bare-chip packaging, System-in-Package (SiP), or multilayer printed circuit boards, ultimately forming a fully functional circuit module. This technology was once widely used in electronic devices with low integration requirements and certain environmental adaptability needs, but its limitations have gradually become apparent in high-precision, miniaturized, and general-purpose applications.

[0038] The motor driver of this invention adopts a universal packaging structure. The motor driver includes a thick-film power circuit, an integrated logic control circuit, a power MOSFET gate drive circuit, an optocoupler isolation circuit, a current limiting protection circuit, and a secondary power supply circuit. These will be described in detail below.

[0039] 1. Thick-film power circuit

[0040] Thick-film power circuits include a three-phase full-bridge inverter circuit, a current sampling circuit, a ceramic substrate, and an aluminum substrate.

[0041] 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 two silicon-based MOSFET bare cores built in. The four bare cores are arranged in a matrix and connected in parallel to form a four-transistor parallel structure. The three-phase full-bridge inverter circuit does not contain a drive resistor.

[0042] The ceramic substrate serves as the physical carrier and structural fixation carrier for components such as the bare MOSFET cores of the three-phase full-bridge inverter circuit and the sampling resistors of the current sampling circuit. It achieves high integration and miniaturization through partitioned and orderly layout, and provides low-impedance electrical connection channels through copper-clad wiring.

[0043] 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.

[0044] The core function of the ceramic substrate is as a carrier for power device integration and power conversion. It employs thick-film technology to directly integrate and package six bare power transistor chips onto its surface, forming an integrated power MOSFET chip, which then constitutes a three-phase inverter bridge circuit. This design reduces the size of traditional discrete power MOSFETs from 53mm×42mm×5.1mm to 20mm×20mm×1.5mm, a reduction of nearly 50% in volume, fundamentally solving the problems of large power transistor size and high integration difficulty in traditional drivers. The ceramic substrate itself possesses excellent insulation and high-temperature resistance, enabling it to meet the high-density packaging requirements of bare-chip integration. It directly undertakes the core function of power conversion, receiving gate drive signals and controlling the energization state of the motor windings, providing power support for motor operation.

[0045] The core function of the aluminum substrate is heat dissipation and a physical support platform. Its key advantage is its extremely high thermal conductivity (far superior to the heat dissipation efficiency of traditional printed circuit boards and ceramic substrates). While it cannot directly integrate power devices or perform power conversion, it is specifically designed to support the ceramic substrate (and the integrated power MOSFET chip on it) and the power sampling resistor. Because the power density is significantly increased after integration into the ceramic substrate, a large amount of heat is generated during operation. The aluminum substrate, through its close contact with the ceramic substrate, can quickly conduct this heat to the driver's metal casing, preventing damage to the power devices due to overheating and ensuring stable operation of the driver under high-power conditions up to 1.5kW. The ceramic substrate, integrating the bare power MOSFET chip, is directly placed on the surface of the aluminum substrate along with the power sampling resistor, forming a composite structure of ceramic substrate attached to the aluminum substrate. This composite structure is the core component of the driver's power board.

[0046] In practical applications, to further improve heat dissipation efficiency and connection stability, the aluminum substrate and ceramic substrate are typically tightly bonded together using a thermally conductive medium (such as thermal grease) to ensure unimpeded heat conduction. Simultaneously, thermal grease is also applied between the aluminum substrate and the driver's standard metal casing, and they are secured with fasteners, forming a complete heat dissipation path: ceramic substrate → thermally conductive medium → aluminum substrate → thermally conductive medium → metal casing, maximizing the thermal conductivity advantage of the aluminum substrate. Furthermore, the fixing method of the ceramic and aluminum substrates must be adapted to the overall structure of the driver to ensure that they do not shift or detach under harsh environments such as high vibration and wide temperature variations, guaranteeing structural reliability.

[0047] 2. Integrated logic control circuit

[0048] The integrated logic control circuit is the control core of the motor driver of this invention, undertaking key functions such as signal processing, timing control, and safety protection logic triggering. Its design, through the use of domestically produced integrated chips and a precise control mechanism, achieves performance advantages of low power consumption, fast response, and high reliability. Specific technical details are as follows:

[0049] (1) Core chip and process characteristics

[0050] The integrated logic control circuit uses the domestically produced System in Package (SiP) integrated chip GKA4096TSA as the core component. This chip is manufactured based on the 0.35um BCDSiGe process and is a dedicated chip specifically designed for 90V power supply and 1kW to 2kW level 3-phase brushless DC motor drive scenarios. It achieves complete independent control from the underlying process to packaging, eliminating the dependence on imported logic chips.

[0051] The chip features a wide operating voltage range of 5V-20V, which, compared to the narrow voltage adaptability of similar logic chips, allows it to be compatible with power supply fluctuations in various electric servo systems without the need for an additional voltage conversion module, simplifying the circuit structure. In terms of power consumption control, the chip excels: the typical static operating current is only 10nA, and the typical dynamic operating current is 10uA, far lower than the power consumption of logic circuits built with traditional discrete components (typically in the μA to mA range), effectively reducing the overall power consumption of the driver and improving the endurance of the electric servo system. Regarding signal response performance, the chip's switching speed and delay parameters are industry-leading: the typical turn-on delay is 40ns (at Vcc=12V), the typical turn-off delay is 35ns, and the typical level transition time is only 15ns. The low transmission delay and fast level transition rate accurately match the requirements of high-speed PWM (Pulse Width Modulation) control, ensuring the real-time performance of motor commutation and speed regulation, and avoiding motor jitter or efficiency loss caused by signal delay.

[0052] (2) Precise control mechanism for EN enable pin

[0053] To address the logic errors caused by voltage fluctuations during motor driver power-on, the integrated logic chip GKA4096TSA features a dedicated EN enable pin. Hierarchical control is implemented via external control circuitry or an RC delay circuit. The specific control logic is as follows:

[0054] Power-on initialization phase: After the driver is connected to 90V power supply, the secondary power supply circuit starts and outputs working voltage to the logic control circuit. At this time, the peripheral control circuit or RC delay circuit will keep the EN enable pin in a low level state, forcing all output signals of the chip to be low level, ensuring that the 6 power MOSFETs of the 3-phase inverter bridge are in the off state, and avoiding false turn-on at the moment of power-on.

[0055] Stable operation startup phase: After the secondary power supply voltage stabilizes and the driver modules complete initialization, the peripheral control circuit or RC delay circuit will trigger the EN enable pin to turn on with a delay (the delay time can be adjusted according to system requirements through RC parameters). The chip switches from standby state to normal working state and begins to receive and process external signals.

[0056] This control mechanism eliminates the risk of logic disorder at the moment of power-on by imposing timing constraints at the hardware level. Its EN control and the logical relationship between power supply, input, and output ensure the visualization and verifiability of the control logic.

[0057] The signal transmission and function implementation of integrated logic control circuits revolve around the core process of signal isolation input, logic calculation, drive signal output, and protection logic triggering. The technical details of each step are as follows:

[0058] 1) Signal Input and Isolation Adaptation: The input terminal of the circuit is directly connected to the output terminal of the optocoupler isolation circuit, receiving two core signals after electrical isolation: the motor commutation signal (F / R, used to control the forward and reverse rotation of the motor) and the speed control signal (PWM, used to adjust the motor speed). Through cooperation with the optocoupler isolation circuit, the influence of external electromagnetic interference on the logic control circuit is effectively blocked, ensuring the integrity and accuracy of the input signal.

[0059] 2) Logic Solving and Drive Signal Generation: The chip integrates a high-precision logic solving unit, capable of real-time processing of the isolated F / R and PWM signals. Based on the state of the F / R signal (forward or reverse), the solving unit matches the corresponding motor commutation timing; combined with the duty cycle of the PWM signal, it precisely controls the conduction time of the power MOSFET, ultimately generating 6 gate control signals that strictly match the motor commutation sequence. The timing accuracy and level driving capability of these signals are fully adapted to the input requirements of the subsequent MOSFET gate floating ground isolation drive circuit.

[0060] 3) Protection Logic Triggering and Collaboration: The signal input terminal of the circuit is also connected to the output terminal of the current limiting protection circuit to receive the current monitoring signal of the power bus in real time. When the current limiting protection circuit detects that the bus current exceeds the preset safety threshold (such as in the case of motor overload, short circuit fault, etc.), it will output an overcurrent protection signal to the logic control circuit. After receiving the signal, the chip will immediately start the emergency protection logic, quickly calculate and output a shutdown signal, and control all power MOSFETs to turn off synchronously through the gate drive circuit, cutting off the power supply to the motor and preventing damage to the power devices and the motor due to overcurrent.

[0061] The aforementioned integrated logic control circuit, through a single-chip integrated design, significantly reduces the number of components and simplifies the circuit form compared to traditional logic circuits built with discrete components such as resistors, capacitors, and logic gates. This results in a reduction of the logic control section's size by more than 30%, while also reducing the impact of parasitic parameters caused by discrete component connections and improving circuit stability. Its wide voltage operating range (5V-20V) adapts to different power supply scenarios, ultra-low power consumption (10nA static / 10uA dynamic) reduces system energy consumption, and fast signal response (delay ≤40ns) ensures motor control accuracy. All parameters are superior to similar logic control solutions, meeting the stringent performance requirements of electric servos for their drivers. The core chip, GKA4096TSA, is entirely domestically developed, eliminating the risk of being "held back" by imported components. Furthermore, the chip uses mature 0.35um BCDSiGe technology, and its operating temperature range covers -55℃ to 125℃, meeting the reliability requirements of harsh environments. The peripheral control circuit of the EN enable pin supports parameter adjustment and can optimize the delay time according to the starting characteristics of different motor models; the logic calculation unit has reserved an expansion interface, which can be configured by software to adapt to three-phase brushless DC motors of different power levels from 1kW to 2kW, which is consistent with the universal design concept of the driver.

[0062] 3. Power MOSFET gate drive circuit

[0063] Figure 1 This is a schematic diagram of the power MOSFET gate drive circuit. The power MOSFET gate drive circuit is the core of the motor driver in this invention for power amplification and isolation. It is responsible for converting the weak gate control signal output from the integrated logic control circuit into a strong drive signal capable of rapidly turning the power MOSFET on / off, while simultaneously achieving the crucial functions of high-voltage isolation and reliable protection. Its design is based on a fully domestically produced chip and innovative architecture, taking into account high voltage withstand capability, low latency, and strong anti-interference characteristics. Specific technical details are as follows:

[0064] (1) Core chip and architecture design

[0065] The core component of the power MOSFET gate drive circuit is a fully domestically produced driver chip. This chip adopts SiP (System in Package) integration technology, which breaks through the design limitations of traditional single-chip gate drivers. It adopts a high-voltage capacitor isolator architecture, which integrates two independent chips, RX (receiver) chip and TX (transmitter) chip, to achieve the dual functions of signal transmission and high-voltage isolation.

[0066] 1) Internal structure and functional division of the chip

[0067] RX (Receiver) Chip: Figure 2 This is a schematic diagram of the circuit principle of the receiver RX chip. The receiver RX chip integrates a high-voltage isolation capacitor, a differential amplifier (Diff AMP), a demodulator (Demodulator), an undervoltage lockout loop (UVLO), a driver, an low-dropout output (LDO), a band gap reference circuit, and a bias circuit. Among these, the high-voltage isolation capacitor is the core isolation component, directly manufactured from the oxide layer in the chip process. It has a simple and reliable structure, a withstand voltage exceeding 2000V, and can effectively block the influence of the high voltage on the power bus on the low-voltage control circuit. The differential amplifier enhances the anti-interference capability of the input signal, the demodulator restores the modulated signal transmitted by the TX chip to the original control signal, the LDO circuit provides stable power to the internal low-voltage module, the band gap circuit provides a precise reference voltage, and the UVLO circuit monitors the supply voltage in real time to ensure that the chip shuts down the output in time when the voltage is abnormal, protecting the power devices.

[0068] TX (transmitter) chip: Figure 3 This is a schematic diagram of the transmitter TX chip. The transmitter TX chip integrates an Input Interface, Logic Control, Modulator, UVLO (Undervoltage Detection Loop), Driver, LDO (Low Dropout Detection), Band Gap, BIAS (Bias Circuit), and Delay Circuit. The input interface is specifically adapted to the gate control signals output by the integrated logic control circuit. The logic control circuit is responsible for the initial signal shaping and timing calibration. The modulator converts the digital control signal into a high-frequency modulated signal suitable for high-voltage isolation transmission. The delay circuit can fine-tune the signal transmission timing to ensure matching with the switching characteristics of the power MOSFET. The UVLO circuit also has undervoltage monitoring functionality to prevent the chip from malfunctioning when the power supply is unstable.

[0069] 2) Key performance parameters

[0070] The chip is optimized for driving 1kW to 2kW three-phase brushless DC motors with 90V power supply.

[0071] With a withstand voltage rating of up to 700V, far exceeding the actual requirements of a 90V power supply system, it provides ample safety margin; the propagation delay is less than 35ns, ensuring a fast response of the gate control signal and avoiding energy loss caused by power MOSFET switching delay; the quiescent current is less than 10mA, and the low-power design reduces the overall energy consumption of the driver; it has a -5V negative voltage withstand capability, which can withstand the impact of voltage fluctuations and adapt to complex electromagnetic environments; the high dV / dt anti-interference capability can effectively suppress electromagnetic interference generated during power device switching and ensure signal transmission integrity; the power supply input range is 10V-20V, which is compatible with the secondary power supply output of different electric servo systems; both VDD (low voltage power supply terminal) and BST (bootstrap power supply terminal) have integrated UVLO undervoltage protection circuits, which automatically shut down the output when the supply voltage is lower than the preset threshold to prevent damage to the power MOSFET due to insufficient drive.

[0072] The high-voltage and low-voltage functional circuits are designed separately and electrically isolated through internal isolation capacitors, ensuring high safety. It adopts a rail-to-rail output mode with output pull-in current of 4A / 6A respectively, which can quickly charge and discharge the gate parasitic capacitance of the power MOSFET, ensuring the power MOSFET to turn on and off quickly and reducing switching losses. The operating temperature range covers -55℃ to 125℃, making it suitable for extreme environmental conditions.

[0073] (2) Design of peripheral auxiliary circuits

[0074] To ensure reliable driving of the upper-arm power MOSFET, a dedicated upper-bridge drive auxiliary circuit is designed around the gate drive circuit of the power MOSFET. This circuit, consisting of diode V4 and capacitor C19, forms a bootstrap drive scheme. The parameter selection is closely related to the characteristics of the power MOSFET and the switching frequency, ensuring sufficient drive capability and circuit safety. Figure 4 This is a schematic diagram of the peripheral circuit of the power MOSFET gate drive circuit. Specific technical details are as follows:

[0075] 1) Design of bootstrap capacitor C19

[0076] Function: When the lower bridge arm power MOSFET is turned on, C19 is charged through the power supply Vcc; when the upper bridge arm control signal is high, C19 discharges as a temporary power supply to charge the gate parasitic capacitance of the upper bridge arm power MOSFET, thereby realizing the turn-on control of the upper bridge arm MOSFET.

[0077] Capacitance calculation: Accurate calculation is required based on the gate charge of the power MOSFET and the operating voltage of the driver chip. The calculation formula is as follows:

[0078] C19>2Qg / (VCC-10-1.5-0.9);

[0079] Where Qg is the gate charge of a single power MOSFET in the 3-phase inverter bridge, and VCC is the operating voltage of the driver chip.

[0080] Actual selection: To ensure drive stability and reserve sufficient design margin, the actual selected capacitance value is 2-3 times the calculated value, and the withstand voltage rating is fixed at 50V, taking into account both withstand voltage performance and size requirements.

[0081] 2) Design of bootstrap diode V4

[0082] Function: When the power MOSFET in the upper bridge arm is turned on, it blocks the high voltage on the power bus, preventing high voltage from flowing back into the driver chip and bootstrap capacitor C19, thus avoiding device damage; at the same time, it reduces the feedback charge loss from C19 to the power supply Vcc, ensuring the charging efficiency of C19.

[0083] Selection requirements: Fast recovery diodes should be given priority, and their reverse leakage current should be as small as possible to reduce charge loss; the voltage rating of the diode must be consistent with that of the power MOSFET to ensure high voltage blocking capability; the reverse recovery time trr should not be greater than 200ns to avoid circuit loss and interference caused by excessive recovery time.

[0084] Forward current calculation: It needs to be calculated based on the gate charge of the power MOSFET, the quiescent current of the driver chip, the transferred charge, and the switching frequency. The calculation formula is as follows:

[0085] IF = 2Qgf + Iqbs(max) + Qlsf;

[0086] Where Qg is the gate charge of the power MOSFET, Iqbs(max) is the maximum static current of the driver chip, Qls is the transferred charge of the diode, and f is the switching frequency (i.e., the PWM control frequency).

[0087] (3) Signal transmission and working principle

[0088] The working process of the power MOSFET gate drive circuit revolves around signal reception, modulation, isolation transmission, demodulation, amplification, driving, and expansion, working in conjunction with integrated logic control circuits and thick-film power circuits. The specific process is as follows:

[0089] Signal reception: The TX chip receives 6 gate control signals (corresponding to the 6 power MOSFETs of the three-phase inverter bridge) output by the integrated logic control circuit through the input interface. These signals are low-voltage weak drive signals and cannot directly drive the power MOSFETs.

[0090] Signal modulation: The logic control circuit inside the TX chip shapes and calibrates the input signal, and then the modulator converts it into a high-frequency modulated signal. This modulated signal can effectively resist electromagnetic interference during high-voltage isolation transmission and ensure signal integrity.

[0091] Isolation transmission: The modulated signal is transmitted through the high-voltage isolation capacitor inside the RX chip. The isolation capacitor blocks the electrical connection between the high-voltage side and the low-voltage side, allowing only the signal to pass through, thus achieving high-voltage isolation.

[0092] Signal demodulation and amplification: After the RX chip receives the modulated signal, the demodulator restores it to the original gate control signal, then the differential amplifier enhances the signal strength, and finally the internal driver circuit amplifies the weak signal into a strong drive signal with a pull-in current of 4A / 6A.

[0093] Power MOSFET drive: The amplified strong drive signal is output to the gate of the power MOSFET in the thick film process power circuit, controlling the power MOSFET to turn on / off according to a preset timing sequence, realizing the alternating energization of the motor windings; at the same time, during PWM speed regulation, the drive signal follows the change of PWM duty cycle, precisely controlling the conduction time of the power MOSFET and adjusting the motor input power.

[0094] (4) Coordination with other circuits

[0095] Coordination with integrated logic control circuit: The input terminal of the circuit (TX chip input interface) is directly connected to the output terminal of the integrated logic control circuit to receive precise gate control signal timing; at the same time, when the integrated logic control circuit receives the overcurrent protection signal from the current limiting protection circuit, it will output a shutdown command, and the power MOSFET gate drive circuit will respond immediately to cut off the drive signal to the power MOSFET, thereby realizing overcurrent protection.

[0096] Coordination with thick-film power circuits: The output of the circuit is directly connected to the gate of the power MOSFET. The voltage amplitude and current capability of the drive signal are precisely matched with the gate characteristics of the power MOSFET to ensure that the power MOSFET operates in the optimal switching state. The bootstrap drive scheme provides a stable drive power supply to the upper bridge arm power MOSFET by linking with the conduction state of the lower bridge arm power MOSFET, thereby realizing the reliable operation of the 3-phase inverter bridge.

[0097] Undervoltage protection coordination: The UVLO circuit inside the chip is linked with the secondary power supply circuit of the driver to monitor the supply voltage in real time. When the secondary power supply output voltage is lower than the preset safety threshold, the UVLO circuit triggers protection and immediately shuts off the drive signal output to prevent the power MOSFET from overheating and being damaged due to insufficient conduction caused by insufficient drive voltage.

[0098] The core driver chip of the aforementioned power MOSFET gate drive circuit is entirely domestically developed, with independent control over chip design, manufacturing process, and packaging and testing. High-voltage isolation capacitors, manufactured using an oxide layer, withstand voltages exceeding 2000V. Compared to traditional pure PN junction voltage designs, they offer more stable isolation performance, lower delay, and the same negative voltage withstand capability as positive voltage withstand, adapting to complex voltage environments. The circuit primarily utilizes low-voltage transistors, significantly reducing the difficulty of chip design and driver hardware layout. The integrated high-voltage isolation capacitor process improves simulation accuracy, ensuring consistency between the design and actual mass production, and reducing product development cycle and cost. A 4A / 6A pull-sink current output and a propagation delay of less than 35ns precisely match the driving requirements of 1kW to 2kW power MOSFETs, reducing switching losses and improving overall driver efficiency. A wide power supply range (10V-20V) adapts to secondary power supplies in different systems, offering strong versatility. It integrates UVLO undervoltage protection and high-voltage isolation protection functions, and works with the high-voltage blocking protection of the external bootstrap diode to form a multi-protection system, which greatly improves the reliability of the driver and reduces the failure rate.

[0099] 4. Optocoupler isolation circuit

[0100] Optocoupler isolation circuits serve as signal isolation barriers for motor drivers. Their core function is to achieve electrical isolation between external control signals and internal low-voltage control circuits, block electromagnetic interference and high-voltage crosstalk, ensure the integrity of signal transmission and the safety of control circuits, and provide reliable input for the accurate calculation of subsequent integrated logic control circuits.

[0101] The optocoupler isolation circuit, connected in series between the external controller and the integrated logic control circuit, is the key interface connecting the external control terminal and the internal control core. Its core function is reflected in two main dimensions:

[0102] Electrical isolation protection: The control signals output by the external controller (motor commutation signal F / R, speed control signal PWM) are completely electrically isolated from the internal integrated logic control circuit. The direct electrical connection between the high-voltage side (power bus 90V) and the low-voltage side (logic circuit 5V-20V) is cut off to prevent high voltage in the power circuit from entering the control side. This avoids damage to the integrated logic chip GKA4096TSA and the external controller due to high voltage surges, and also eliminates interference caused by ground potential differences between different circuit modules.

[0103] Signal fidelity transmission: While achieving isolation, it accurately restores the timing and amplitude characteristics of external control signals, ensuring that the forward and reverse logic of commutation signals and the PWM duty cycle of speed control signals are not distorted. This provides an accurate signal input basis for integrated logic control circuits and avoids abnormal motor operation (such as commutation jitter and reduced speed control accuracy) caused by signal distortion.

[0104] The coordination between the optocoupler isolation circuit and other circuits is as follows:

[0105] (1) Coordination with integrated logic control circuit: The isolated signal output by the optocoupler is directly connected to the signal input terminal of the integrated logic chip GKA4096TSA. Its output level (high level ≥ 4.5V, low level ≤ 0.5V) is precisely matched with the chip input threshold, ensuring that the chip can accurately identify the signal logic;

[0106] (2) Isolation and coordination with power circuit: By electrically isolating the strong electromagnetic interference (dV / dt interference) generated during the switching process of the power MOSFET, the strong electromagnetic interference (dV / dt interference) is blocked from entering the control side, avoiding signal calculation errors in the logic chip due to interference. At the same time, it prevents the high voltage fault on the power side (such as power MOSFET breakdown) from spreading to the external controller, forming a double protection.

[0107] (3) Coordination with system power supply: The power supply of the optocoupler input terminal is taken from the power supply of the external controller, and the power supply of the output terminal is taken from the secondary power supply inside the driver (from the same source as the integrated logic control circuit). The two power supply systems are independent of each other and have no common ground interference, further ensuring the isolation effect;

[0108] (4) Signal integrity assurance: In view of the high frequency characteristics of the speed control signal (PWM), the selection of optocouplers focuses on controlling the consistency of transmission delay. Optocouplers used to transmit F / R signals and PWM signals in the same driver are selected from the same batch of devices to ensure that the delay deviation of the two signals is ≤10ns, so as to avoid the timing misalignment of motor commutation and speed control due to inconsistent signal delay. At the same time, the pull-up resistor value at the output of the optocoupler is designed with impedance matching to reduce the oscillation of signal rising / falling edges and ensure signal fidelity.

[0109] 5. Current limiting protection circuit

[0110] The current-limiting protection circuit is the core of the safety protection for the motor driver of this invention. Its core function is to monitor the power bus current in real time and accurately throughout the entire path. It provides microsecond-level response and graded protection against various overcurrent faults such as motor overload, winding short circuit, and abnormal conduction of the power MOSFET. Without affecting normal operation, it cuts off the power output path, preventing core components from burning out or suffering irreversible performance damage. It also has fault diagnosis and status feedback capabilities, providing full lifecycle safety assurance for the drive system. Specific technical details are as follows:

[0111] The current limiting protection circuit is connected in series between the 90V and 56V power input terminals and the thick-film process power circuit. It acts as a safety gate on the power transmission path, and its core function covers three dimensions, while ensuring comprehensive protection and timely response:

[0112] Full-condition current monitoring: It not only monitors the load current when the motor is running stably, but also accurately captures the inrush current at the moment of startup, the dynamic current fluctuation during speed regulation, and the instantaneous large current spike during sudden faults, achieving dead-angle current perception and ensuring that any abnormal current scenario can be identified.

[0113] Graded fault response: Based on the degree of overcurrent, it is divided into two levels of mechanism: overload protection and short circuit protection. In case of overload (current exceeds the rated value by 1.2-1.5 times), derating operation or delayed shutdown is triggered first to avoid false triggering; in case of short circuit (current exceeds the rated value by more than 3 times), forced shutdown is executed immediately to resist the impact of instantaneous large current.

[0114] Safety linkage and status feedback: Through hard-wired linkage with integrated logic control circuit, closed-loop protection of detection, judgment and execution is realized; at the same time, a fault feedback interface is reserved to output overcurrent fault signals to external controllers, which facilitates system problem location, and supports manual / automatic reset mode to adapt to the fault handling needs of different application scenarios.

[0115] The current limiting protection circuit does not operate independently, but rather works in deep collaboration with other core circuits of the driver to form a multi-layered, fast-response, and safe and controllable protection system.

[0116] (1) Synergy with integrated logic control circuits

[0117] Priority linkage: The overcurrent protection signal is directly connected to the dedicated INT pin of the integrated logic chip GKA4096TSA through a hard wire. The response priority of this pin is higher than that of the commutation signal (F / R) and the speed control signal (PWM), ensuring that the protection action is executed first in case of a fault and avoiding logic conflicts.

[0118] Dynamic threshold adjustment: The logic chip can be configured by software to adjust the threshold voltage of the comparator to adapt to the rated current of motors with different power levels from 1kW to 2kW (e.g., set the overload threshold to 10A for a 1kW motor and 20A for a 2kW motor), thereby improving the versatility of the driver.

[0119] Fault recording and diagnosis: After receiving the protection signal, the logic chip records the time of the fault occurrence, the fault type (overload / short circuit), and the current value at the time of the fault, and feeds it back to the external controller through the communication interface for easy troubleshooting later.

[0120] (2) Synergy with the gate drive circuit of power MOSFET

[0121] Fast shutdown linkage: The shutdown command output by the logic chip directly triggers the chip's emergency shutdown pin (SD pin). The response time of this pin is ≤10ns, which is faster than the normal shutdown path, ensuring that the power MOSFET is turned off in the shortest possible time.

[0122] Dual undervoltage protection: The internal UVLO undervoltage protection and current limiting protection complement each other. If the current limiting protection circuit fails and the power MOSFET experiences a sudden voltage drop due to overcurrent, the UVLO circuit will trigger undervoltage shutdown to prevent device damage.

[0123] (3) Synergy with thick film process power circuits

[0124] Full-path monitoring: The sampling resistor is connected in series at the power bus input terminal to directly monitor the total current of the 3-phase inverter bridge, ensuring that any abnormal conduction of any power MOSFET (such as normal conduction caused by gate breakdown) can be quickly detected and triggered for protection.

[0125] Heat dissipation coordination: Both the sampling resistor and the integrated power MOSFET are arranged on an aluminum substrate. The high thermal conductivity of the aluminum substrate can quickly dissipate the power loss of the sampling resistor, avoid resistance drift caused by overheating, and ensure detection accuracy.

[0126] (4) Coordination with secondary power supply circuit

[0127] Power redundancy protection: The secondary power supply circuit provides independent power (12V±5%) for the current limiting protection circuit and integrates overvoltage / undervoltage protection to ensure that the current limiting protection circuit can still work stably when the power supply fluctuates.

[0128] Fault power failure linkage: In the event of a severe short circuit fault, the current limiting protection circuit can trigger the output shutdown of the secondary power supply circuit through the logic chip, completely cutting off the power supply to all modules inside the driver and preventing the fault from spreading.

[0129] 6. Secondary power supply circuit

[0130] The secondary power supply circuit is a key supporting unit of the integrated motor driver of this invention. Its core function is to provide stable and matched operating voltages for the various modules inside the driver, ensuring the reliable implementation of core functions such as logic operations, gate driving, and signal isolation. This circuit adopts a highly integrated design, integrating with the logic control circuit, gate driving circuit, etc., on the logic board. Electromagnetic compatibility is optimized through multi-layer board partitioning, avoiding power supply noise from interfering with other sensitive circuits.

[0131] In terms of voltage conversion, the secondary power supply circuit receives the externally input 90V main power supply voltage, which is converted by a high-efficiency linear voltage regulator circuit to output multiple precise and stable low-voltage power supplies. Specifically, it provides a wide-range (5V-20V) power supply for the integrated logic chip GKA4096TSA, meeting the operating voltage requirements of its 0.35um BCDSiGe process and ensuring the chip's low-power operation characteristics of 10nA static and 10uA dynamic; it provides a 10V-20V compliant power supply for the power MOSFET gate driver chip, supporting the normal operation of its internal LDO (low dropout output circuit), BandGap (bandgap reference), and driver circuit, ensuring the driver chip achieves performance indicators such as 700V withstand voltage and less than 35ns propagation delay; and it provides isolated and stable power supplies for the optocoupler isolation circuit and current limiting protection circuit. The optocoupler isolation power supply must meet the insulation requirements for signal isolation transmission, while the current limiting protection circuit power supply ensures the accuracy of current acquisition and protection signal output.

[0132] The circuit features a comprehensive voltage stabilization and protection mechanism, integrating overvoltage and undervoltage protection functions. When the input voltage fluctuates abnormally or the output voltage exceeds the set threshold, it can quickly cut off the output or activate clamping protection to prevent damage to core components such as logic chips and driver chips due to abnormal voltage. The built-in filtering module effectively reduces power ripple and noise through multi-stage capacitor filtering and electromagnetic interference suppression design, ensuring power quality and providing a foundation for the accuracy of logic calculation and the integrity of gate drive signals. In addition, the circuit also features low power consumption characteristics, consistent with the overall miniaturization and low power consumption design concept of the driver. Its own power consumption is controlled at an extremely low level, without affecting the overall power density improvement of the driver.

[0133] The design of the secondary power supply circuit is compatible with the stacked soldering architecture of the logic board and power board. The electrical contacts are reliably connected to the external pins and internal modules through metal solder pads and copper wires. Its power supply stability directly determines the processing accuracy of the commutation signal (F / R) and speed control signal (PWM) of the 3-phase brushless motor, as well as the response speed of the overcurrent protection signal. It is an important guarantee for achieving the goals of driver integration, generalization, and miniaturization, ensuring that the driver provides continuous and stable power support for 1kW to 2kW 3-phase brushless DC motors within the operating temperature range of -55℃ to 125℃.

[0134] 7. Standardized packaging structure

[0135] The universal packaging structure adopted by the motor driver of this invention is the core carrier for achieving multi-scenario adaptation, high integration density, and strong environmental tolerance. Through layered integration, standardized design, and multi-functional fusion architecture, the power board, logic board, and various auxiliary components are packaged into an integrated module, which not only ensures the stable operation of the internal circuit, but also realizes the universal application of different system models, while taking into account the stringent requirements of heat dissipation, electromagnetic shielding, and vibration resistance.

[0136] (1) Key performance parameters of the generalized packaging structure

[0137] The core positioning of the universal packaging structure is as a carrier for functional integration, a bridge for universal adaptation, and a barrier for environmental protection. Regarding universal adaptation, standardized dimensions, mounting interfaces, and electrical interfaces allow the driver to be adapted to various models of 1kW to 2kW 90V-powered three-phase brushless DC motors without structural modifications. In terms of integrated compactness, a layered layout and high-density packaging maximize the reduction of overall volume. Combined with thick-film technology and integrated chips, the driver size is reduced by more than 50% compared to traditional solutions. Regarding reliability protection, multiple protection functions, including heat dissipation, electromagnetic shielding, vibration resistance, and sealing, are integrated to ensure long-term stable operation of the driver in a wide temperature range of -55℃ to 125℃, high vibration, and strong electromagnetic interference environments.

[0138] The general-purpose packaging structure has a three-layer architecture: outer shell, internal stacked modules, and interface components. The core components include a general-purpose metal shell, power board, logic board, connection components, and auxiliary protection components. All parts work together to form an integrated driver module.

[0139] Universal metal housing: As the outer protective layer and functional carrier of the encapsulation structure, it is made of high-strength aluminum alloy (such as 6061-T6), CNC machined and surface-conductively anodized, combining lightweight, high rigidity, electromagnetic shielding and heat dissipation characteristics; the housing is designed with standardized dimensions (such as 80mm long × 60mm wide × 10mm high) to fit the installation space of mainstream electric servos, and multiple sets of mounting holes are reserved to accommodate different system fixing methods.

[0140] Power board: The core load-bearing component, with an aluminum substrate as the bottom base, and a ceramic substrate power circuit (integrated power MOSFET chip), power sampling resistor, filter capacitor and other power devices fixed on the surface, forming a composite power load-bearing structure of "aluminum substrate + ceramic substrate", which is both the core path for power signal transmission and the key carrier for heat dissipation.

[0141] Logic board: The core carrier for integrated control and drive. It adopts a six-layer PCB design and integrates integrated logic control circuit (GKA4096TSA chip), power MOSFET gate drive circuit, optocoupler isolation circuit, current limiting protection circuit and secondary power supply circuit. Multi-layer wiring and partitioned layout improve integration density and electromagnetic compatibility.

[0142] Connection components: including metal solder pads, copper wires, board-to-board connectors and external interface terminals, are responsible for the internal electrical connection between the power board and the logic board, as well as the external connection between the driver and the external power supply, controller and motor.

[0143] Auxiliary protective components include thermal grease, shock-absorbing pads, sealant, grounding posts, etc., used to enhance heat dissipation, vibration resistance, sealing protection and electromagnetic shielding performance.

[0144] (2) Layered integration and internal connection design

[0145] The stacked layout of the power board and logic board adopts a "top and bottom stacked welding" structure, with the logic board on the upper layer and the power board on the lower layer. The two boards are positioned by four sets of metal support pillars with a spacing of 3mm to 5mm. This ensures that the electrical clearance meets the high voltage insulation requirements (≥2mm) and also reserves space for heat dissipation and welding connections. The stacked design increases the three-dimensional space utilization of the driver by 40% and significantly reduces the overall volume.

[0146] Internal electrical connections: The electrical contacts between the power board and the logic board adopt a hybrid connection method of "metal solder pads + copper wire". High current signals (such as power bus and motor winding connection terminals) are soldered with copper metal solder pads with a thickness of 0.5mm to 1mm to reduce contact resistance and parasitic inductance and avoid high current heating; small signals (such as control signals and protection signals) are bonded with gold-plated copper wires with a diameter of 25μm to 50μm to adapt to high-density pin layout; all solder joints adopt ultrasonic welding process with a welding strength ≥5N to adapt to high vibration environment.

[0147] Secondary power supply circuit integration: The secondary power supply circuit (providing stable 5V / 12V power to the logic board and driver circuit) is integrated into the edge area of ​​the logic board. The 90V input voltage is converted to low voltage through the linear voltage regulator circuit on the board. The power module is connected to the power area of ​​the logic board through wide copper foil wiring to reduce power supply noise.

[0148] (3) Metal casing and protective design

[0149] Housing structure details: The housing adopts a split design of "top cover + base". The base has a recessed structure, and the power board and logic board are fixed inside the base with fasteners. The top cover is fastened to the base with 4 Phillips head countersunk screws. The joint is equipped with a silicone sealing gasket, and the sealing level reaches IP65, which can effectively prevent dust, moisture and salt spray, and is suitable for harsh environments. The inner wall of the housing has 3 longitudinal heat dissipation ribs that are attached to the surface of the aluminum substrate of the power board to increase the heat dissipation contact area.

[0150] Electromagnetic shielding design: The aluminum alloy shell itself constitutes a complete electromagnetic shielding cavity. The surface contact resistance after conductive oxidation treatment is ≤0.1Ω, which can effectively shield the influence of external electromagnetic interference (EMI) on the internal circuit, while blocking the leakage of electromagnetic radiation generated by the internal power MOSFET switch. The inside of the shell is sprayed with conductive shielding paint, and a grounding spring is set between the logic board and the shell to ensure a reliable connection between the grounding plane of the logic board and the shell, further improving the shielding effect (shielding effectiveness ≥40dB@1GHz).

[0151] Vibration and shock resistant design: The power board and logic board are isolated from the base by anti-vibration pads (made of silicone rubber, Shore 70A hardness). The anti-vibration pads are 2mm to 3mm thick and can absorb 10g to 20g of vibration impact. All fasteners (screws, support columns) are designed to prevent loosening (with anti-loosening washers or anti-loosening adhesive) to avoid loosening of connections due to vibration. Chips and key components are all surface-mount packaged with lead length ≤1mm to reduce the risk of stress fracture caused by vibration.

[0152] (4) Heat dissipation structure design

[0153] Multi-level heat dissipation path: A three-level heat dissipation architecture of "device-substrate-casing-environment" is adopted. The power MOSFET chip is mounted on the ceramic substrate, and the ceramic substrate is attached to the aluminum substrate with thermal grease (thermal conductivity ≥3.0W / (m·K)). The bottom of the aluminum substrate and the heat dissipation fins of the casing base are tightly attached with thermal grease and tightened with 4 bolts. The bolt torque is controlled between 5N.m and 8N.m to ensure that there are no gaps in heat conduction. The heat dissipation fins on the surface of the casing increase the heat dissipation area (30% more than a smooth surface). Under natural heat dissipation conditions, it can meet the heat dissipation requirements of 2kW power conditions. If enhanced heat dissipation is required, the casing is provided with heat sink installation interface, which can be expanded with forced air cooling or water cooling modules.

[0154] Enhanced local heat dissipation: The aluminum substrate area under heat-generating devices such as power sampling resistors and DC-DC power modules uses thickened copper foil (thickness ≥105μm) and has thermally conductive vias (0.8mm diameter, 2mm spacing) to quickly conduct heat to the back of the aluminum substrate; small heat sinks (copper material, size 5mm×5mm×2mm) are mounted on the surface of the driver chip and integrated logic chip GKA4096TSA on the logic board, and are attached to the chip with thermally conductive adhesive to assist in heat dissipation.

[0155] (5) Logic board partition layout design

[0156] As a multi-layer PCB, the logic board adopts the layout principle of "functional partitioning + signal isolation" to further improve electromagnetic compatibility and reliability.

[0157] Zoning Layout: The logic board is divided into four main areas: power supply area, digital control area, analog signal area, and power drive area. The power supply area is close to the secondary power supply module and uses wide copper foil wiring and decoupling capacitor array (0.1μF ceramic capacitor + 10μF tantalum capacitor) to suppress power supply noise. The digital control area (integrating GKA4096TSA chip) is located in the center of the logic board, away from power devices. A 2mm wide grounding isolation strip is set between the analog signal area (optical isolation circuit, current limiting protection circuit) and the digital control area. The power drive area is close to the edge of the logic board and is connected to the signal interface of the power board nearby to shorten the drive signal path.

[0158] Wiring rules: High-speed signals (such as PWM signals and drive signals) should use impedance-controlled wiring (characteristic impedance 50Ω) with a length ≤5cm to avoid signal reflection; differential signals (such as differential output of sampling resistors) should use equal-length, parallel wiring with a spacing of 0.3mm to 0.5mm to improve anti-interference capability; power wiring and signal wiring should maintain a spacing of ≥3mm to avoid electromagnetic coupling.

[0159] (6) General standardization implementation method

[0160] A standardized packaging structure achieves seamless compatibility with different system models through size and interface standardization.

[0161] Standardized dimensions: The length, width, and height of the housing are designed to be fixed specifications (e.g., 80mm×60mm×25mm). The mounting holes adopt a symmetrical layout of 4 holes with a diameter of 3mm and a hole spacing of 70mm (length) and 50mm (width), which is compatible with the mounting hole distribution of mainstream electric servos. Traditional drives can be directly replaced without modifying the mounting structure.

[0162] Interface standardization: Standardized interface components are integrated on the side of the casing, including:

[0163] Power interface: Uses a 2-pin connector, compatible with 90V DC power input, and features reverse connection protection (opposite layout of positive and negative pins).

[0164] Signal interface: It adopts an 8-pin connector, integrating commutation signal (F / R), speed control signal (PWM), reset signal, fault feedback signal, etc. The pin definitions are standardized and compatible with the output interfaces of different external controllers.

[0165] Motor interface: Uses 3-pin connector to connect to 3-phase motor windings, with pin spacing ≥2mm to meet high voltage insulation requirements;

[0166] All interfaces are secured with snap-fit ​​fasteners, with a plug-in / plug-out life of ≥1000 cycles and a contact resistance of ≤10mΩ.

[0167] Functional Adaptation: The logic board has a reserved parameter debugging interface, which can modify the timing of the integrated logic chip GKA4096TSA by modifying the resistor and capacitor parameters to adapt to the rated current and starting characteristics of motors with different power ratings from 1kW to 2kW; the sampling resistor value of the power board can be adjusted by replacing the plug-in resistor (reserved resistor pad), and in conjunction with the threshold adjustment of the current limiting protection circuit, overcurrent protection adaptation for different motors can be achieved without modifying the package structure.

[0168] (7) Coordination and cooperation with other modules

[0169] The standardized packaging structure does not exist independently, but rather works closely with the core circuitry inside the driver, forming a linkage between structural support and functional dependence:

[0170] Synergy with the power board: The heat dissipation architecture of the housing provides a heat dissipation channel for the ceramic substrate power circuit. The tight fit between the aluminum substrate and the housing ensures that the heat of the integrated power MOSFET is dissipated quickly, supporting a high power output of 1.5kW. The high-voltage insulation design of the housing (internal electrical clearance ≥2mm) matches the 90V and 56V operating voltage of the power bus, avoiding the risk of high-voltage breakdown.

[0171] Synergy with the logic board: The partitioned layout of the logic board complements the electromagnetic shielding function of the casing. The casing blocks external electromagnetic interference, and the grounding isolation strip of the logic board suppresses electromagnetic coupling of the internal circuits, jointly ensuring the stable operation of the integrated logic chip and driver chip. The vibration-resistant design of the casing protects the precision components on the logic board and prevents the solder joints from falling off or the chips from failing due to vibration.

[0172] Synergy with optocoupler isolation circuit and current limiting protection circuit: The sealed protection function of the housing prevents environmental factors such as moisture and salt spray from affecting the performance of sensitive devices such as optocouplers and comparators; electromagnetic shielding reduces interference signals from false triggering of the protection circuit, ensuring the detection accuracy and response reliability of the current limiting protection circuit.

[0173] In summary, the technical solution of this invention addresses the problems of difficult testing, poor anti-interference, and large size and limited versatility of existing pure thick-film circuit motor drivers, as well as pure printed circuit board designs. It adopts a thick-film substrate + bare chip integrated packaging, fully domestically produced components, and a universal metal packaging design to construct a modular motor driver integrating logic control, gate drive, optocoupler isolation, and current limiting protection. The low-power, fast-response logic chip, fabricated using a 0.35um BCDSiGe process, achieves a high-voltage (700V) and low-latency (<35ns) gate drive circuit through a high-voltage capacitor isolation architecture. It also utilizes a thick-film integration process that reduces the size of discrete power MOSFETs by nearly 50%. Furthermore, the logic board and power board employ stacked soldering and multi-layer board partitioning to optimize electromagnetic compatibility. This solution ultimately achieves stable driving of 1kW to 2kW three-phase brushless DC motors powered by 90V or 56V. It achieves the technical effects of high driver integration, fewer components, significantly reduced size, and lower power consumption. Furthermore, the universal packaging can be adapted to multiple system models, and the use of all domestically produced components ensures independent control. The operating temperature range covers -55℃ to 125℃, significantly improving the practicality and reliability of the driver.

[0174] 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.

[0175] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. 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 invention should be included within the scope of protection of this invention.

Claims

1. A motor driver based on a thick-film substrate, characterized in that, The motor driver adopts a generalized packaging structure and includes a thick-film process power circuit, an integrated logic control circuit, a power MOSFET gate drive circuit, an optocoupler isolation circuit, a current limiting protection circuit, and a secondary power supply circuit. Thick-film power circuits include a three-phase full-bridge inverter circuit, a current sampling circuit, a ceramic substrate, and an aluminum substrate. The integrated logic control circuit uses domestically produced SiP integrated chips to perform signal processing, timing control, and safety protection logic triggering functions. The gate drive circuit of the power MOSFET adopts a fully domestically produced drive chip, which converts the weak gate control signal output by the integrated logic control circuit into a strong drive signal that can drive the power MOSFET to turn on / off quickly, while realizing high voltage isolation and protection functions. Optical isolation circuits are connected in series between the external controller and the integrated logic control circuit for electrical isolation protection and signal fidelity transmission; The current limiting protection circuit is connected in series between the power supply input terminal and the thick film process power circuit to monitor the power bus current throughout the entire path. Through linkage with the integrated logic control circuit, it realizes closed-loop protection of detection, judgment and execution. The secondary power supply circuit provides a stable and matched operating voltage for each module inside the motor driver; The three-phase full-bridge inverter circuit consists of three power switch modules with the same structure, 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. 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 current.

2. The motor driver based on a thick-film substrate according to claim 1, characterized in that, Each power switch module has two built-in silicon-based MOSFET bare cores; the two 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.

3. A motor driver based on a thick-film substrate according to claim 1, characterized in that, The ceramic substrate serves as the physical carrier and structural fixation carrier for the bare MOSFET cores of the three-phase full-bridge inverter circuit and the sampling resistors of the current sampling circuit. By employing thick-film technology, six bare power transistor chips are directly integrated and packaged on its own surface to form an integrated power MOSFET chip, thereby constituting a three-phase inverter bridge circuit.

4. A motor driver based on a thick-film substrate according to claim 3, characterized in that, A ceramic substrate integrating a power MOSFET bare chip is directly placed on the surface of an aluminum substrate along with a sampling resistor, forming a composite structure in which the ceramic substrate is attached to the aluminum substrate.

5. A motor driver based on a thick-film substrate according to claim 1, characterized in that, The general-purpose packaging structure is a three-layer architecture consisting of an outer shell, internal stacked modules, and interface components. It includes a general-purpose metal shell, power board, logic board, connection components, and auxiliary protection components. All parts work together to form an integrated drive module.

6. A motor driver based on a thick-film substrate according to claim 5, characterized in that, The power board uses an aluminum substrate as its base and a ceramic substrate is fixed on its surface.

7. A motor driver based on a thick-film substrate according to claim 5, characterized in that, The logic board adopts a six-layer PCB design, with integrated logic control circuit, power MOSFET gate drive circuit, optocoupler isolation circuit, current limiting protection circuit and secondary power supply circuit integrated on the surface.

8. A motor driver based on a thick-film substrate according to claim 1 or 7, characterized in that, The power board and logic board adopt an upper and lower stacked welding structure, with the logic board on the upper layer and the power board on the lower layer. The two boards are positioned by multiple sets of metal support pillars.

9. A motor driver based on a thick-film substrate according to claim 5, characterized in that, The electrical contacts between the power board and the logic board use a hybrid connection method of metal solder pads and copper wires. High current signals are soldered through metal solder pads, while low current signals are bonded through copper wires.

10. A motor driver based on a thick-film substrate according to claim 5, characterized in that, The general-purpose metal casing adopts a split design of top cover and base. The base has a groove structure, and the power board and logic board are fixed inside the base with fasteners.

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