A hopper dryer controller step-down power module

Abstract

The utility model discloses a kind of injection molding hopper dryer controller step-down power module, comprising: input power terminal, for connecting direct-current power supply;Step-down controller;Three-stage parallel input filter capacitor group, including large-capacity electrolytic capacitor, medium-capacity capacitor and small-capacity high-frequency capacitor;Inductance, connect the switch output end of the step-down controller;Schottky freewheeling diode, anode ground, cathode connects the node between the inductance and the switch output end of the step-down controller;Two-stage output filter capacitor group, including large-capacity output capacitor and high-frequency filter capacitor;Feedback voltage division network, including pull-up resistor and pull-down resistor, connect between output end and the feedback input end of the step-down controller;Bootstrap capacitor, connect between the bootstrap end and switch output end of the step-down controller.This injection molding hopper dryer controller step-down power module has the characteristics of high efficiency, low noise, high reliability.

Description

Technical Field

[0001] This utility model relates to a step-down power supply module for a plastic injection hopper dryer controller. Background Technology

[0002] Plastic injection molding and extrusion are indispensable processes in modern industrial production. To ensure the processing quality of plastic raw materials, almost all injection molding and extrusion processes require drying to remove moisture adsorbed in the plastic granules. This is because most engineering plastics have a certain degree of hygroscopicity; if the moisture content is too high, hydrolysis will occur during high-temperature processing, leading to a decrease in the mechanical properties of the product and defects such as bubbles, discoloration, or yellowing on the surface.

[0003] The hopper dryer is a key piece of equipment in this process. It heats air and blows it into a hopper containing plastic raw materials, causing the materials to lose moisture at a specific temperature. Modern hopper dryers are generally equipped with sophisticated control systems to monitor and adjust parameters such as drying temperature, airflow, and time, while also collecting information such as material level and humidity. These control systems typically include microcontrollers, various sensors, communication modules, and human-machine interfaces, all requiring a stable 5V DC power supply.

[0004] Traditional hopper dryer controller power supply designs mainly employ two methods: one is a linear regulator (such as the 7805 series), which has the advantages of simple design and low cost, but its efficiency is low. Especially when the input voltage is high, the excess energy is dissipated as heat, which wastes energy and increases the heat dissipation burden; the other is a switching power supply built with discrete components. Although the efficiency is improved, due to the dispersed layout of components, it often occupies a large PCB area, and the electromagnetic interference (EMI) control is poor, which can easily affect the measurement accuracy of temperature and airflow sensors in the dryer.

[0005] Furthermore, the working environment of plastic processing equipment generally involves harsh factors such as high temperature, dust, and vibration. In particular, hopper dryers typically operate at temperatures ranging from 80-150℃, and the electronic components of the controller operate under these high temperatures for extended periods, making heat dissipation a significant issue. Simultaneously, dust generated during the transportation and handling of plastic granules can enter the controller, accumulating on the circuit board and affecting heat dissipation and electrical insulation performance.

[0006] In this special environment, existing power modules face several major problems: first, insufficient heat dissipation leads to a shortened lifespan of components; second, insufficient anti-interference capability affects the measurement accuracy of sensors.

[0007] Therefore, there is an urgent need to develop a step-down power supply module specifically designed for the controller of injection molding hopper dryer, which can operate efficiently and reliably in high-temperature and dusty environments, has good electromagnetic compatibility, and is compatible with multiple input voltages to meet the special needs of modern plastic processing equipment. Utility Model Content

[0008] The purpose of this invention is to provide a step-down power supply module for a plastic injection hopper dryer controller. This step-down power supply module for a plastic injection hopper dryer controller features high efficiency, low noise, and high reliability.

[0009] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0010] A step-down power supply module for a plastic injection hopper dryer controller includes: an input power terminal for connecting to a DC power supply; a step-down controller; a three-stage parallel input filter capacitor bank, including a large-capacity electrolytic capacitor, a medium-capacity capacitor, and a small-capacity high-frequency capacitor; an inductor connected to the switching output terminal of the step-down controller; a Schottky freewheeling diode, with its anode grounded and its cathode connected to the node between the inductor and the switching output terminal of the step-down controller; a two-stage output filter capacitor bank, including a large-capacity output capacitor and a high-frequency filter capacitor; a feedback voltage divider network, including pull-up resistors and pull-down resistors, connected between the output terminal and the feedback input terminal of the step-down controller; and a bootstrap capacitor connected between the bootstrap terminal and the switching output terminal of the step-down controller.

[0011] The present invention is further configured such that the three capacitors in the three-stage parallel input filter capacitor bank adopt a decreasing capacitance design, wherein the large-capacity electrolytic capacitor is 330μF, the medium-capacity capacitor is 10μF, and the small-capacity high-frequency capacitor is 100nF, forming a wideband filter structure.

[0012] The present invention is further configured such that: the inductor adopts a large inductance value of 15μH, and together with the Schottky freewheeling diode, forms a low current ripple step-down conversion structure.

[0013] The present invention is further configured such that the connection traces between the buck controller, the inductor, the Schottky freewheeling diode and the output capacitor form a layout with minimum loop area.

[0014] The present invention is further configured such that the Schottky freewheeling diode has a withstand voltage of 40V, which is used to adapt to a wide range of input voltages of 12-24V.

[0015] The present invention is further configured such that the large-capacity output capacitor in the dual-stage output filter capacitor bank is 220μF and the high-frequency filter capacitor is 100nF, forming a dual suppression structure for low-frequency ripple and high-frequency spike.

[0016] The present invention is further configured such that the pull-up resistor and pull-down resistor of the feedback voltage divider network are configured to stabilize the output voltage at 5V.

[0017] The present invention is further configured such that: the bootstrap capacitor is connected to the bootstrap terminal and the switch output terminal of the buck controller through the shortest possible trace, forming a high-side drive circuit with the smallest loop area.

[0018] In summary, this utility model has the following beneficial effects:

[0019] Three-stage parallel input filter structure: This invention employs a three-stage parallel input filter capacitor bank consisting of a large-capacity electrolytic capacitor (330μF), a medium-capacity capacitor (10μF), and a small-capacity high-frequency capacitor (100nF) to form a wide-bandwidth filter structure. This decreasing capacitance design leverages the filtering advantages of each capacitor at different frequency bands: the large capacitor handles low-frequency ripple, the medium-capacity capacitor filters mid-frequency interference, and the small-capacity high-frequency capacitor suppresses high-frequency spikes. This effectively prevents external interference from entering the system and also prevents the module's own switching noise from being transmitted to other devices, improving the stability and anti-interference capability of the entire control system.

[0020] Low electromagnetic interference design: This invention employs an external Schottky diode combined with a 15μH large inductor for a low-noise design, reducing current ripple and switching noise at the source. The wiring between the step-down controller, inductor, Schottky freewheeling diode, and output capacitor forms a minimum loop area layout, reducing the loop area compared to standard designs and lowering radiated EMI. This low-EMI design is particularly important for sensitive sensors in hopper dryers, and in practical applications, it can improve temperature control accuracy by approximately 1-2℃, making the drying process more precise and controllable.

[0021] Wide input voltage adaptability: The Schottky freewheeling diode in this design has a 40V withstand voltage, which, in conjunction with the feedback voltage divider network, enables the module to operate stably under a wide input voltage range of 12-24V, outputting a constant 5V voltage. This design allows the same module to adapt to various power supply environments, connecting to the 12V adapter of a stand-alone drying unit or the 24V busbar of a centralized feeding system. This reduces the variety of items in inventory, significantly simplifies spare parts management, and lowers maintenance costs and equipment downtime.

[0022] Dual-band output filtering design: This utility model's dual-stage output filter capacitor bank includes a 220μF large-capacity output capacitor and a 100nF high-frequency filter capacitor, forming a dual suppression structure for low-frequency ripple and high-frequency spikes. This is crucial for the microprocessor, communication circuits, and sensor signal conditioning circuits in the dryer controller, reducing power supply noise interference to measurements and improving the stability of the entire control system. Simultaneously, the large-capacity output capacitor provides sufficient energy storage capacity, enhancing the system's anti-interference capability. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of this utility model. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings.

[0025] like Figure 1 As shown, this utility model provides a step-down power supply module for a plastic injection hopper dryer controller, including an input power terminal (DC1), a step-down controller (U11), a three-stage parallel input filter capacitor bank (C21, C22, C23), an inductor (L2), a Schottky freewheeling diode (D4), a two-stage output filter capacitor bank (C24, C25), a feedback voltage divider network (R39, R40), and a bootstrap capacitor (C20).

[0026] The input power terminal (DC1) is used to connect to a DC power supply and adopts a standard DC power socket, compatible with common 2.1mm or 2.5mm coaxial power plugs. The terminal is mounted via on-board soldering, ensuring a secure connection and reliable contact, and can withstand frequent plugging and unplugging operations.

[0027] The buck controller (U11) is the core control component of the entire module. It uses an integrated circuit chip in a PowerPAD package, typically the TPS54331. The buck controller (U11) is installed in the central area of ​​the circuit board, close to the input capacitor array, so that VIN (pin 7) is close to the input power supply and PH (pin 8) points towards the inductor, optimizing the trace length.

[0028] The three-stage parallel input filter capacitor bank consists of a large-capacity electrolytic capacitor (C21), a medium-capacity capacitor (C22), and a small-capacity high-frequency capacitor (C23). These three capacitors are designed with decreasing capacitance values: the large-capacity electrolytic capacitor (C21) is 330μF, the medium-capacity capacitor (C22) is 10μF, and the small-capacity high-frequency capacitor (C23) is 100nF, forming a wideband filter structure. The large electrolytic capacitor (C21) is vertically mounted close to the power input; the medium-capacity capacitor (C22) and the small-capacity high-frequency capacitor (C23) are surface-mounted, placed around the large-capacity electrolytic capacitor (C21) to form a star-shaped layout. This structure allows each capacitor to leverage its filtering advantages across different frequency bands: the large capacitor handles low-frequency ripple, the medium-capacity capacitor filters intermediate-frequency interference, and the small-capacity high-frequency capacitor suppresses high-frequency spikes, collectively forming a wideband filter network from 10Hz to 100MHz.

[0029] The inductor (L2) is connected to the switching output (PH) of the buck controller (U11) and features a large 15μH inductance value. The inductor is mounted immediately adjacent to the PH (pin 8) output of the buck controller (U11). The input and PH pins are directly connected using wide traces, and the output points towards the output capacitor. The large inductance value, combined with the switching frequency (approximately 330kHz), creates low current ripple characteristics, effectively reducing electromagnetic radiation and losses.

[0030] The Schottky freewheeling diode (D4) has its anode grounded and its cathode connected to the node between the inductor (L2) and the switching output (PH) of the buck controller (U11). The diode is in an SMD package, typically SMA or SMB type, model B340A, with a 40V withstand voltage to accommodate a wide input voltage range of 12-24V. An extended copper layer surrounds the diode to increase heat dissipation area and reduce operating temperature. The connection traces between the Schottky freewheeling diode and the buck controller, inductor, and output capacitor form a minimum loop area layout, reducing parasitic inductance and electromagnetic radiation.

[0031] The dual-stage output filter capacitor bank includes a large-capacity output capacitor (C24) and a high-frequency filter capacitor (C25). The large-capacity output capacitor (C24) is 220μF and is vertically mounted; the high-frequency filter capacitor (C25) is 100nF and is surface-mounted. The two are closely arranged to form a dual suppression structure for low-frequency ripple and high-frequency spikes. The large-capacity output capacitor (C24) primarily handles low-frequency load changes, providing energy reserves; the high-frequency filter capacitor (C25) is used to suppress high-frequency switching noise. Together, they provide a clean DC power supply to the subsequent circuitry.

[0032] The feedback voltage divider network includes pull-up resistors (R39) and pull-down resistors (R40), connected between the output terminal and the feedback input (VSENSE) of the buck controller (U11). The pull-up and pull-down resistors are configured to stabilize the output voltage at 5V; their specific values ​​need to be calculated and determined based on the controller's internal reference voltage. The sampling resistors are arranged in series, with R39 connected to the output terminal and R40 connected to ground. The sampling signal lines use thin traces but are kept short to reduce noise interference. The feedback network is kept at an appropriate distance from the main power loop to avoid interference from switching noise on the sampling signal.

[0033] The bootstrap capacitor (C20) is connected between the bootstrap terminal (BOOT) and the switching output terminal (PH) of the buck controller (U11). It is a surface-mount ceramic capacitor with a capacitance of 100nF. The bootstrap capacitor (C20) is connected to the bootstrap terminal (BOOT) and the switching output terminal of the buck controller through the shortest possible trace, forming a high-side drive circuit with the smallest loop area, ensuring sufficient and stable gate drive voltage for the high-side MOSFET.

[0034] The working principle of this invention is as follows: The input DC power supply is connected to a three-stage parallel input filter capacitor bank (C21, C22, C23) through the input power terminal (DC1) for filtering and energy storage. The high-side MOSFET inside the buck controller (U11) switches the energy of the input power supply to the inductor (L2) through the switch output terminal (PH). When the switch is on, the current in the inductor (L2) rises linearly, and energy is stored in the inductor (L2); when the switch is off, the Schottky freewheeling diode (D4) conducts, providing a loop for the current in the inductor (L2), and the current in the inductor (L2) decreases linearly, transferring energy to the output capacitor and the load. The output voltage is fed back to the feedback input terminal (VSENSE) of the controller through the feedback voltage divider network (R39, R40), compared with the internal reference voltage, and the controller adjusts the switching duty cycle to stabilize the output voltage at 5V. The bootstrap capacitor (C20) provides a floating power supply for the high-side drive circuit inside the controller, ensuring that the high-side MOSFET can be fully turned on. The dual-stage output filter capacitor bank (C24, C25) filters the output voltage, eliminates switching ripple, and provides a clean DC power supply for the subsequent circuits.

[0035] Furthermore, in practical applications, the step-down power supply module of this utility model can be finely adjusted according to the different requirements of the hopper dryer controller: for applications requiring higher output current, the current rating of the inductor (L2) and the current capacity of the diode (D4) can be increased accordingly; for applications that particularly value low noise, the inductor value can be appropriately increased to 22μH or 33μH to further reduce current ripple; for applications with particularly tight space, a step-down controller integrating power MOSFETs and diodes can be considered to reduce the overall size.

[0036] This utility model's step-down power supply module, through reasonable structural design and component selection, solves the thermal management, electromagnetic interference, and compatibility problems faced by traditional power supplies in injection molding hopper dryer controllers. It provides a high-efficiency, low-noise, and high-reliability power supply solution, which is especially suitable for plastic processing equipment that operates stably for a long time in dusty and high-temperature environments.

[0037] The present invention employs the following experiments to evaluate the technical effectiveness of the step-down power supply module for the controller of the injection molding hopper dryer.

[0038] 1. Verification employs a comparative testing method, comparing the performance of this utility model's step-down power supply module with two traditional power supply solutions (linear regulator and conventional switching power supply). The test environment simulates the real operating conditions of the hopper dryer controller, including ambient temperature cycling tests (25℃ to 85℃) and electromagnetic interference tests. Parameter measurements are performed using professional equipment such as thermal imagers, high-precision oscilloscopes, spectrum analyzers, and power analyzers. Each test is repeated five times, and the average value is taken to ensure data reliability.

[0039] 2. Technical Effect Comparison Table

[0040] 3. Verification Methods and Results

[0041] Thermal management performance testing: An 85℃ high-temperature environmental chamber was used to simulate the high-temperature working environment of a hopper dryer, while plastic dust was added to the PCB surface to simulate actual working conditions. After 8 hours of continuous full-load operation, the controller junction temperature of this PowerPAD module was only 88℃, far lower than the 125℃ of a linear regulator and the 110℃ of a conventional switching power supply. Thermal imaging analysis showed that heat was evenly distributed on both sides of the PCB with no obvious hot spots, while traditional solutions formed obvious hot spots around key components, accelerating aging.

[0042] EMI Suppression Testing: Conducted and radiated interference (EMI) of the three solutions in the 10kHz-30MHz frequency band was measured using a spectrum analyzer. This module radiated 68dBμV at the critical 150kHz frequency, 17dB lower than the conventional switching power supply. When the module was connected to a temperature measurement system equipped with a type K thermocouple (sensitivity 40μV / ℃), the temperature reading jitter of this module solution was only ±0.5℃, while the conventional switching power supply solution reached ±2.3℃, verifying the positive impact of low-EMI design on sensitive sensors.

[0043] Energy conversion efficiency testing: Efficiency was measured at different load currents (0.5A, 1A, 2A) under both 12V and 24V input voltages. This module achieved an efficiency of 87% with a 24V input and a 2A load, compared to only 20.8% for a linear regulator and approximately 75% for a conventional switching power supply. This efficiency improvement directly translates to reduced heat generation; under the same operating conditions, this module generates approximately 76% less heat than a linear solution and approximately 48% less heat than a conventional switching solution.

[0044] Wide voltage compatibility testing: The stability and efficiency of the module were tested when the input voltage continuously varied from 10V to 30V. The results show that this module can maintain the output voltage within 5V±2% within the range of 12-26V, with an efficiency of over 80%. Traditional solutions usually require designing different module models for different input voltage ranges, leading to increased inventory and maintenance complexity.

[0045] 4. Verification Conclusion

[0046] Through comprehensive testing and verification, the step-down power supply module of this utility model exhibits excellent performance in high-temperature and dusty environments. Its core technological advantages include: a three-dimensional heat dissipation structure that effectively reduces the controller junction temperature by 20-30% and extends its service life by 2-5 times; a low-EMI design that reduces electromagnetic interference by 17dB and significantly improves the measurement accuracy of the temperature sensor; high energy conversion efficiency (318% higher than linear solutions) that reduces heat generation and optimizes overall system heat dissipation; and wide voltage adaptability that allows the same module to be used in various drying equipment, greatly simplifying spare parts management. These advantages make this module particularly suitable for long-term stable operation in demanding industrial environments such as injection molding hopper dryer controllers, effectively addressing the shortcomings of traditional power supply modules in terms of high temperature, reliability, and compatibility.

Claims

1. A step-down power supply module for a plastic injection hopper dryer controller, characterized in that, include: Input power terminal (DC1) is used to connect a DC power supply; Step-down controller (U11); The three-stage parallel input filter capacitor bank includes a large-capacity electrolytic capacitor (C21), a medium-capacity capacitor (C22), and a small-capacity high-frequency capacitor (C23). An inductor (L2) is connected to the switching output (PH) of the buck controller (U11); A Schottky freewheeling diode (D4) is connected to a node between the inductor (L2) and the switching output terminal (PH) of the buck controller (U11). A two-stage output filter capacitor bank, including a large-capacity output capacitor (C24) and a high-frequency filter capacitor (C25); The feedback voltage divider network, including pull-up resistors (R39) and pull-down resistors (R40), is connected between the output terminal and the feedback input terminal (VSENSE) of the buck controller (U11); The bootstrap capacitor (C20) is connected between the bootstrap terminal (BOOT) and the switching output terminal (PH) of the buck controller (U11).

2. The step-down power supply module for the controller of the injection molding hopper dryer according to claim 1, characterized in that, The three capacitors in the three-stage parallel input filter capacitor bank adopt a decreasing capacitance design, with the large-capacity electrolytic capacitor (C21) being 330μF, the medium-capacity capacitor (C22) being 10μF, and the small-capacity high-frequency capacitor (C23) being 100nF, forming a wideband filter structure.

3. The step-down power supply module for the controller of the injection molding hopper dryer according to claim 1, characterized in that, The inductor (L2) is designed with a large inductance value of 15μH, and together with the Schottky freewheeling diode (D4), it forms a step-down conversion structure with low current ripple.

4. The step-down power supply module for the injection molding hopper dryer controller according to claim 1, characterized in that, The connection traces between the buck controller (U11), the inductor (L2), the Schottky freewheeling diode (D4), and the large-capacity output capacitor (C24) form a layout with minimum loop area.

5. The step-down power supply module for the controller of the injection molding hopper dryer according to claim 1, characterized in that, The Schottky freewheeling diode (D4) has a voltage rating of 40V and is used to adapt to a wide input voltage range of 12-24V.

6. The step-down power supply module for the controller of the injection molding hopper dryer according to claim 1, characterized in that, The dual-stage output filter capacitor bank includes a large-capacity output capacitor (C24) of 220μF and a high-frequency filter capacitor (C25) of 100nF, forming a dual suppression structure for low-frequency ripple and high-frequency spikes.

7. The step-down power supply module for the controller of the injection molding hopper dryer according to claim 1, characterized in that, The pull-up resistor (R39) and pull-down resistor (R40) of the feedback voltage divider network are configured to stabilize the output voltage at 5V.

8. The step-down power supply module for the controller of the injection molding hopper dryer according to claim 1, characterized in that, The bootstrap capacitor (C20) is connected to the bootstrap terminal (BOOT) and the switching output terminal (PH) of the buck controller (U11) via the shortest path, forming a high-side drive circuit with the smallest loop area.

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