A power supply filter circuit and a power supply

Abstract

A power filter circuit and power supply, the power filter circuit includes filter module, PWM module, switch module and output module, the input end of filter module is connected first power port, the output end of filter module is connected the input end of PWM module and the input end of switch module, the controlled end of switch module is connected the control end of PWM module, the feedback end of PWM module is connected the output module, the output end of switch module is connected the input end of output module, the output end of output module is connected the second power port, the embodiment of the utility model realizes wide frequency noise absorption and voltage clamping through the collaborative work of filter module, PWM module, switch module and output module, has the advantages of efficient inhibition wide frequency noise, fast dynamic response and compact structure reduces cost.

Description

Technical Field

[0001] This utility model relates to the field of power supply technology, specifically to a power supply filtering circuit and a power supply. Background Technology

[0002] In medical electronic equipment, power quality directly affects the system's performance and reliability. A common practice is to incorporate filtering and voltage regulation at the power input, such as using a small capacitor in parallel for high-frequency bypass, employing an RC / LC network to suppress ripple and spikes, and then using a linear regulator or switching regulator to power the load.

[0003] However, the power supplies in existing medical electronic devices mostly use RC or LC passive networks, or linear regulators and switching regulators to form the power supply front end. Among them, the RC structure is simple, but it is insufficient for suppressing low-frequency ripple and transient surges; although LC can improve low-frequency ripple, it requires a large inductor / capacitor, which increases the size and cost, and its effect on suppressing MHz-level spikes is limited; linear regulators have low efficiency, generate a lot of heat, and lack the ability to dynamically absorb large input fluctuations; ordinary switching regulators focus on energy conversion, and if they lack wideband suppression at the input end and clamping / smoothing at the output end, they are prone to overshoot, ringing and electromagnetic interference at the moment of load change or plugging and unplugging, making it difficult to meet the comprehensive indicators of high-frequency noise, low-frequency ripple and surge suppression and stable output under the conditions of small size and low cost. Utility Model Content

[0004] The purpose of this utility model is to address the defects and deficiencies of the existing technology by providing a power supply filtering circuit, including a filtering module, a PWM module, a switching module, and an output module. The input terminal of the filtering module is connected to a first power port, the output terminal of the filtering module is connected to the input terminal of the PWM module and the input terminal of the switching module, the controlled terminal of the switching module is connected to the control terminal of the PWM module, the feedback terminal of the PWM module is connected to the output module, the output terminal of the switching module is connected to the input terminal of the output module, and the output terminal of the output module is connected to a second power port.

[0005] Furthermore, the filtering module includes a capacitor C1 and an inductor L1. The capacitor C1 is located between the first power port and the second power port. One end of the inductor L1 is connected to the capacitor C1 and the first power port, and the other end of the inductor L1 is connected to the switching module and the PWM module.

[0006] Furthermore, the switching module includes a switching transistor Q1, the controlled terminal of the switching transistor Q1 is connected to the control terminal of the PWM module, the input terminal of the switching transistor Q1 is connected to the other end of the inductor L1, and the output terminal of the switching transistor Q1 is connected to the output module.

[0007] Furthermore, the switching module also includes a diode D1, a resistor R1, and a capacitor C2. The cathode of the diode D1 is connected to one end of the capacitor C2 and the output terminal of the switching transistor Q1. The anode of the diode D1 is connected to one end of the resistor R1, the power supply terminal of the PWM module, and the input terminal of the switching transistor Q1. The other end of the resistor R1 and the other end of the capacitor C2 are connected to the second power port.

[0008] Furthermore, the PWM module includes a PWM control unit, a capacitor C3 is provided between the ground terminal and the power supply terminal of the PWM control unit, and a resistor R2 is provided between the power supply terminal of the PWM control unit and the input terminal of the switching module.

[0009] Furthermore, the output module includes a Zener diode ZD1, the cathode of which is connected to the output terminal of the switching module, and the anode of which is connected to the second power supply port.

[0010] Furthermore, the output module also includes a resistor R3 and a load resistor RL, one end of which is connected to the output terminal of the switching module, and the other end is connected to the second power port.

[0011] Furthermore, the switching transistor Q1 is a transistor.

[0012] On the other hand, this utility model also provides a power supply, including the power supply filtering circuit described above.

[0013] This utility model embodiment utilizes the coordinated operation of a filtering module, a PWM module, a switching module, and an output module. At the input end, LC filtering suppresses high-frequency interference, and the PWM module dynamically adjusts the duty cycle of the switching module. Combined with the Zener diode at the output end, it achieves wideband noise absorption and voltage clamping. It has the advantages of efficient suppression of wideband noise, fast dynamic response, and compact structure that reduces costs. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a circuit structure block diagram of an embodiment of the present utility model; Figure 2 This is a schematic diagram of the circuit principle of an embodiment of the present utility model; Figure label: 100. Filtering circuit; 200. PWM module; 300. Switch module; 400. Output module. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the accompanying drawings.

[0017] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive element, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] In existing technologies, power supply systems for medical electronic devices generally employ an architecture combining RC or LC passive filter networks with linear regulators or switching regulators. While the RC structure is simple, it struggles to effectively suppress low-frequency ripple and transient surges. Although LC networks improve low-frequency characteristics, they require large inductors and capacitors, limiting device miniaturization. Linear regulators suffer from low efficiency and high heat generation, while ordinary switching regulators are prone to output overshoot and electromagnetic interference during dynamic response, making it difficult to achieve a balance between wideband noise suppression and stable output within a compact space. When medical devices encounter sudden load changes or external interference, traditional power supply systems may experience voltage fluctuations, affecting the normal operation of precision electronic circuits.

[0021] To address the aforementioned issues, a power supply architecture capable of simultaneously suppressing high-frequency noise, absorbing low-frequency ripple, and optimizing dynamic response is needed. In traditional solutions, passive filtering and active voltage regulation modules often operate independently, lacking a coordinated control mechanism. Introducing pulse width modulation (PWM) technology to actively intervene in the filtering process can improve the system's adaptability to input fluctuations. Combining switching actions with feedback control can create multiple suppression paths across different frequency bands. Simultaneously, it is necessary to avoid the increased size caused by complex circuitry; therefore, modular design is needed to integrate filtering, control, and output functions.

[0022] Therefore, refer to Figure 1 This application proposes a power supply filtering circuit, including a filtering module, a PWM module 200, a switching module 300, and an output module 400. The input terminal of the filtering module is connected to a first power supply port, the output terminal of the filtering module is connected to the input terminals of the PWM module 200 and the switching module 300, the controlled terminal of the switching module 300 is connected to the control terminal of the PWM module 200, the feedback terminal of the PWM module 200 is connected to the output module 400, the output terminal of the switching module 300 is connected to the input terminal of the output module 400, and the output terminal of the output module 400 is connected to a second power supply port.

[0023] Among them, the filtering module refers to the circuit unit that performs preliminary filtering of the input power supply; the PWM module 200 refers to the control module that generates pulse width modulation signals; the switching module 300 refers to the module that contains semiconductor devices that control the conduction power path, which can be implemented by field-effect transistors or insulated gate bipolar transistors, and quickly switches the current path according to the control signal; the output module 400 refers to the circuit unit that performs final regulation of the processed electrical energy.

[0024] Compared with existing technologies, the filtering and voltage regulation functions in traditional solutions are implemented independently by discrete components. However, this application realizes the dynamic coordination of each module through the feedback control of the PWM module 200, which can simultaneously suppress MHz-level high-frequency spikes and low-frequency ripple interference in the power supply system of medical equipment and effectively absorb instantaneous surge energy.

[0025] Furthermore, refer to Figure 2 This application proposes a filtering module including a capacitor C1 and an inductor L1. The capacitor C1 is located between the first power port and the second power port. One end of the inductor L1 is connected to the capacitor C1 and the first power port, and the other end of the inductor L1 is connected to the switching module 300 and the PWM module 200.

[0026] In this design, capacitor C1 is a filter capacitor connected across the power input terminal, which can be implemented using an electrolytic capacitor or a ceramic capacitor. It is used to absorb high-frequency noise and stabilize the input voltage. Inductor L1 is a filter inductor connected in series in the power path, which can be implemented using a ferrite core inductor or a wire-wound inductor. It is used to suppress low-frequency ripple and limit current surges. Capacitor C1 is connected in parallel between the first power port and the second power port, forming a high-frequency bypass path on the input side, which can quickly absorb high-frequency interference signals at the power input terminal. One end of inductor L1 is connected to capacitor C1 and the first power port, and the other end is connected to the switching module 300 and the PWM module 200. Through the inductance characteristics, it impedes instantaneous changes in current, thereby filtering out low-frequency ripple. Capacitor C1 and inductor L1 together form an LC filter structure, which simultaneously achieves high-frequency noise suppression and low-frequency ripple attenuation in a compact layout, avoiding the size increase problem caused by too many discrete components in traditional RC or LC networks.

[0027] This application further proposes a switching module 300 including a switching transistor Q1. The controlled terminal of the switching transistor Q1 is connected to the control terminal of the PWM module 200, the input terminal of the switching transistor Q1 is connected to the other end of the inductor L1, and the output terminal of the switching transistor Q1 is connected to the output module 400. The controlled terminal of the switching transistor Q1 refers to the pin that receives external control signals, which can be implemented using the gate or base terminal. The switching transistor Q1's on and off frequencies are controlled by receiving the pulse width modulation signal from the PWM module 200. The input terminal of the switching transistor Q1 refers to the current input path connecting the switching transistor Q1 and the inductor L1, which can be implemented using the drain or collector terminal. It is used to receive the electrical energy filtered by the inductor L1. The output terminal of the switching transistor Q1 refers to the current output path connecting the switching transistor Q1 and the output module 400, which can be implemented using the source or emitter terminal. It is used to transfer the regulated electrical energy to the voltage regulation stage of the output module 400.

[0028] Specifically, the controlled terminal of the switching transistor Q1 receives pulse signals from the PWM module 200 to control its on / off cycle. Its input terminal is connected to inductor L1 to receive filtered electrical energy, and its output terminal transfers the electrical energy to the voltage regulation unit of the output module 400. When the PWM module 200 adjusts the pulse width according to the feedback signal from the output module 400, the on-time of the switching transistor Q1 changes accordingly, thereby regulating the voltage stability of the output module 400. For example, during sudden load changes or input voltage fluctuations, the PWM module 200 dynamically adjusts the duty cycle of the switching transistor Q1 to maintain the voltage of the output module 400 within a preset range.

[0029] This application further proposes that the switching module 300 also includes a diode D1, a resistor R1, and a capacitor C2. The cathode of the diode D1 is connected to one end of the capacitor C2 and the output terminal of the switching transistor Q1, and the anode of the diode D1 is connected to one end of the resistor R1, the power supply terminal of the PWM module 200, and the input terminal of the switching transistor Q1. The other end of the resistor R1 and the other end of the capacitor C2 are connected to the second power supply port. When the switching transistor Q1 is in the on state, the inductor L1 stores energy. At this time, the diode D1 is in the off state due to reverse bias. The capacitor C2 forms a discharge circuit with the second power supply port through the resistor R1 to maintain the stability of the output voltage. When the switching transistor Q1 is off, the reverse electromotive force generated by the inductor L1 causes the diode D1 to conduct in the forward direction, forming a freewheeling path to release the inductor's stored energy. At the same time, the capacitor C2 quickly absorbs the high-frequency noise at the output terminal of the switching transistor through the diode D1, and the resistor R1 limits the current change at the power supply terminal of the PWM module 200, thereby synergistically suppressing surge voltage and high-frequency interference.

[0030] This application further proposes a power supply filtering circuit. The PWM module 200 includes a PWM control unit. A capacitor C3 is provided between the ground terminal and the power supply terminal of the PWM control unit, and a resistor R2 is provided between the power supply terminal of the PWM control unit and the input terminal of the switching module 300.

[0031] The PWM control unit refers to the integrated circuit module that generates pulse width modulation signals. Specifically, it can be implemented using a dedicated chip with error amplification, oscillation and driving functions. It is used to adjust the duty cycle of the switching module 300 according to the feedback signal from the output module 400.

[0032] Among them, capacitor C3 refers to the filter element connected between the power supply terminal and the ground terminal of the PWM control unit. Specifically, it can be implemented using a ceramic capacitor or an electrolytic capacitor, which is used to absorb high-frequency noise in the power supply line and maintain the stability of the operating voltage of the PWM control unit.

[0033] Among them, resistor R2 is a current-limiting element connected in series between the power supply terminal of the PWM control unit and the input terminal of the switching module 300. Specifically, it can be implemented by using a metal film resistor or a carbon film resistor to limit the current surge from the input terminal of the switching module 300 to the power supply terminal of the PWM control unit, and at the same time form an RC filter network with capacitor C3.

[0034] Preferably, the PWM control unit can use a PWM controller of model OB2273AMP, or other dedicated PWM control chips or microcontroller modules with the same or similar functions to achieve error amplification, oscillation and driving functions.

[0035] Specifically, the PWM control unit generates a feedback signal by detecting voltage changes in the output module 400, and adjusts the duty cycle of the PWM signal output to the switching module 300. Capacitor C3 bypasses high-frequency interference at the power supply terminal of the PWM control unit, preventing power supply noise from affecting the generation accuracy of the PWM signal; resistor R2 forms impedance isolation between the input terminal of the switching module 300 and the power supply terminal of the PWM control unit, suppressing voltage surges caused by switching actions from interfering with the power supply quality of the PWM control unit.

[0036] It should be noted that the combination structure of the above-mentioned PWM control unit, capacitor C3 and resistor R2 is a common design method in this field, which can be implemented by those skilled in the art without creative effort. Therefore, equivalent substitutions can be made by using the same or similar circuit structures without departing from the concept of this application.

[0037] Reference Figure 2 This application further proposes that the output module 400 includes a Zener diode ZD1, the cathode of which is connected to the output terminal of the switch module 300, and the anode of which is connected to the second power supply port. The Zener diode ZD1 is a semiconductor device with reverse breakdown voltage characteristics. When the voltage at the output terminal of the switch module 300 increases due to load changes or input fluctuations, the Zener diode ZD1 enters the reverse breakdown state, and the voltage between its cathode and anode is clamped to the breakdown voltage value. At this time, the current exceeding the breakdown voltage flows through the Zener diode to the second power supply port, thereby suppressing the abnormal rise of the output voltage.

[0038] This embodiment can effectively suppress voltage overshoot and ringing caused by sudden load changes or insertion / removal, ensuring the stability of the output voltage and avoiding device damage due to overvoltage.

[0039] Reference Figure 2 This application further proposes that the output module 400 also includes a load resistor RL. One end of the load resistor RL is connected to the output terminal of the switching module 300, and the other end is connected to the second power supply port. The load resistor RL is a resistive element connected in parallel across the output module 400, which can be a carbon film resistor, a metal film resistor, or a wire-wound resistor. The load resistor RL is used to prevent voltage spikes from occurring in the switching module 300 under no-load or light-load conditions due to the inability to release energy. When the switching module 300 is in the on state, the energy stored in the inductor is transferred to the output terminal through the switching transistor. At this time, the load resistor RL and the Zener diode together form a current discharge path, converting excess energy into heat energy for consumption, thereby suppressing instantaneous fluctuations in the output voltage. When the load changes abruptly or the device is plugged in or unplugged, the load resistor RL can maintain a minimum current loop, avoiding abnormal feedback signals from the PWM module 200 due to sudden changes in loop impedance, thereby reducing the probability of ringing.

[0040] Preferably, the switching transistor Q1 is a transistor, which can achieve fast switching action while maintaining low cost and effectively reduce high-frequency ringing and electromagnetic interference.

[0041] In one embodiment, the output module 400 further includes a resistor R3, one end of which is connected to the cathode of the Zener diode ZD1, and the other end is connected to the switching module 300. By introducing the resistor R3 into the output module 400 and forming a synergistic suppression structure with the Zener diode ZD1, this embodiment achieves active-passive joint suppression of switching node overshoot, inductor flyback ringing, and the resulting EMI without significantly increasing the size and cost. This further improves the broadband stability and electromagnetic compatibility margin of the power supply for medical electronic equipment in a compact space.

[0042] Furthermore, this application proposes a power supply including a power filtering circuit. The power filtering circuit includes a filtering module, a PWM module 200, a switching module 300, and an output module 400. The input terminal of the filtering module is connected to a first power port, the output terminal of the filtering module is connected to the input terminals of the PWM module 200 and the switching module 300, the controlled terminal of the switching module 300 is connected to the control terminal of the PWM module 200, the feedback terminal of the PWM module 200 is connected to the output module 400, the output terminal of the switching module 300 is connected to the input terminal of the output module 400, and the output terminal of the output module 400 is connected to a second power port.

[0043] Compared to existing technologies, traditional power supply front-ends using RC or LC passive filter networks struggle to simultaneously suppress high-frequency noise and attenuate low-frequency ripple, and require large inductors or capacitors. This application, however, utilizes the collaborative operation of the filter module and the PWM module 200 to suppress interference over a wide frequency range, while simultaneously reducing energy loss through the efficient switching characteristics of the switching module 300. Furthermore, the voltage regulation design of the output module 400 effectively handles voltage fluctuations caused by sudden load changes or insertion / removal, preventing overshoot and ringing.

[0044] Through the above technical solutions, this application can simultaneously achieve high-frequency noise suppression, low-frequency ripple attenuation, and dynamic surge absorption in a compact structure, thereby improving the stability and reliability of power output. It is especially suitable for medical electronic equipment that is sensitive to electromagnetic interference and requires long-term stable operation.

[0045] The above is only used to illustrate the technical solution of this utility model and not to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of this utility model, as long as they do not depart from the spirit and scope of the technical solution of this utility model, should be covered within the scope of the claims of this utility model.

Claims

1. A power supply filtering circuit, characterized in that, The system includes a filter module, a PWM module (200), a switch module (300), and an output module (400). The input terminal of the filter module is connected to a first power supply port. The output terminal of the filter module is connected to the input terminal of the PWM module (200) and the input terminal of the switch module (300). The controlled terminal of the switch module (300) is connected to the control terminal of the PWM module (200). The feedback terminal of the PWM module (200) is connected to the output module (400). The output terminal of the switch module (300) is connected to the input terminal of the output module (400). The output terminal of the output module (400) is connected to a second power supply port.

2. The power supply filtering circuit according to claim 1, characterized in that, The filtering module includes a capacitor C1 and an inductor L1. The capacitor C1 is located between the first power port and the second power port. One end of the inductor L1 is connected to the capacitor C1 and the first power port, and the other end of the inductor L1 is connected to the switching module (300) and the PWM module (200).

3. The power supply filtering circuit according to claim 2, characterized in that, The switching module (300) includes a switching transistor Q1, the controlled terminal of the switching transistor Q1 is connected to the control terminal of the PWM module (200), the input terminal of the switching transistor Q1 is connected to the other end of the inductor L1, and the output terminal of the switching transistor Q1 is connected to the output module (400).

4. The power supply filtering circuit according to claim 3, characterized in that, The switching module (300) further includes a diode D1, a resistor R1, and a capacitor C2. The cathode of the diode D1 is connected to one end of the capacitor C2 and the output terminal of the switching transistor Q1. The anode of the diode D1 is connected to one end of the resistor R1, the power supply terminal of the PWM module (200), and the input terminal of the switching transistor Q1. The other end of the resistor R1 and the other end of the capacitor C2 are connected to the second power supply port.

5. The power supply filtering circuit according to claim 1, characterized in that, The PWM module (200) includes a PWM control unit, a capacitor C3 is provided between the ground terminal and the power supply terminal of the PWM control unit, and a resistor R2 is provided between the power supply terminal of the PWM control unit and the input terminal of the switching module (300).

6. The power supply filtering circuit according to claim 5, characterized in that, The output module (400) includes a Zener diode ZD1, the cathode of which is connected to the output terminal of the switching module (300), and the anode of which is connected to the second power supply port.

7. The power supply filtering circuit according to claim 6, characterized in that, The output module (400) further includes a resistor R3 and a load resistor RL. One end of the resistor R3 and the load resistor RL are connected to the output terminal of the switch module (300), and the other end is connected to the second power port.

8. The power supply filtering circuit according to claim 3, characterized in that, The switching transistor Q1 is a transistor.

9. A power supply, characterized in that, Includes the power supply filtering circuit as described in any one of claims 1-8.

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