Circuit capable of satisfying EMI and preventing surge high voltage from damaging internal capacitor of module
By absorbing surge voltage through a unidirectional conducting device connected in parallel in the PFC circuit, the problem of easy damage to the internal circuitry of the power module is solved. At the same time, EMI filtering and surge protection are achieved, saving module design space.
Patent Information
- Application Number
- CN202422350920.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2026-01-27
- Estimated Expiration
- 2034-09-25
AI Technical Summary
Existing power modules are prone to internal electrical damage when exposed to surge voltages, and EMI filtering circuits cannot effectively provide surge protection.
In a PFC circuit, a unidirectional conducting device, such as a diode or a field-effect transistor, is connected in parallel to absorb surge voltage, ensuring that the internal capacitor is not damaged, while maintaining the EMI filtering function.
It effectively protects internal capacitors from surge high voltage damage, reduces EMI interference, and saves module design space.
Smart Images
Figure CN223843690U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of power supplies, specifically a circuit that satisfies both EMI requirements and prevents surge high voltage damage to the internal capacitors of the module. Background Technology
[0002] Due to size limitations, power brick-type modules can only accommodate ceramic capacitors and surface-mount inductors as filtering components. In AC brick power supplies, high-voltage energy storage capacitors can only be placed outside the module. Since the ceramic capacitors inside the module and the external energy storage capacitors are placed on different boards and are far apart, a surface-mount inductor is connected in series between these two capacitors for EMI considerations. This inductor and the ceramic capacitors form a filtering circuit to suppress EMI.
[0003] The AC module input first goes to the PFC circuit, where ceramic capacitors are placed at the PFC output for filtering. External capacitor C4 is what stabilizes the output. However, since the distance between C1 and C4 is usually quite far, an inductor L1 is used to filter high-frequency noise on the line.
[0004] The input is connected to the AC power grid, and will inevitably encounter surge voltages. For example, the induced voltage from a lightning strike at the moment the power equipment is switched on will be reflected on the input line and transmitted to the power module input terminal. Because of the presence of the L1 inductor in this circuit, the inductor will block voltage changes, so a large voltage spike will be generated on C1-C3 during surge voltage, which may damage the capacitors or even other electronic components. Utility Model Content
[0005] The purpose of this invention is to provide a circuit that satisfies both EMI requirements and prevents surge high voltage damage to the internal capacitors of the module, thereby solving the problems mentioned in the background art.
[0006] To achieve the above objectives, this utility model provides the following technical solution: a circuit that satisfies both EMI and prevents surge high voltage damage to the internal capacitors of the module, including a PFC circuit. One end of the PFC circuit is connected to an input power supply, and the output end of the PFC circuit is connected to an inductor L1. Capacitors C1, C2, and C3 are connected at the junction between the PFC circuit and the inductor L1, respectively. Capacitors C1, C2, and C3 are all connected in parallel and grounded. A unidirectional conducting device is connected in parallel across the two ends of the inductor L1. Capacitor C4 is connected to the output end of the inductor L1, and capacitor C4 is connected in parallel with the inductor L1. The output end of the inductor L1 is connected to a base-collector voltage.
[0007] Preferably, the unidirectional conducting device is a diode.
[0008] Preferably, the unidirectional conducting device is a field-effect transistor.
[0009] Preferably, the unidirectional conducting device is a thyristor.
[0010] Compared with the prior art, the beneficial effects of this utility model are:
[0011] This invention uses a parallel unidirectional conducting device to allow the surge voltage to pass through its forward conduction, and the surge energy is absorbed by the energy storage capacitor, thereby ensuring that the internal components are not damaged by overvoltage. The unidirectional conduction characteristic of the diode will not affect the filtering function of the inductor L1, which reduces EMI interference and provides surge protection. Moreover, the structure is simple and saves a lot of board space in the module design. Attached Figure Description
[0012] Figure 1 This is a circuit diagram illustrating how this utility model satisfies both EMI requirements and prevents surge high voltage damage to the internal capacitors of the module. Detailed Implementation
[0013] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0014] Please see Figure 1 This utility model provides a technical solution: a circuit that satisfies EMI and solves the problem of surge high voltage damaging the internal capacitors of the module, including a PFC circuit. One end of the PFC circuit is connected to an input power supply, and the output end of the PFC circuit is connected to an inductor L1. Capacitors C1, C2, and C3 are connected at the junction between the PFC circuit and the inductor L1, respectively. Capacitors C1, C2, and C3 are all connected in parallel and grounded. A unidirectional conducting device is connected in parallel across the two ends of the inductor L1. The unidirectional conducting device is a diode. In some embodiments, the unidirectional conducting device can be a field-effect transistor or a thyristor.
[0015] A capacitor C4 is connected to the output terminal of inductor L1. The capacitor C4 is connected in parallel with inductor L1. The output terminal of inductor L1 is connected to the base-collector voltage. A unidirectional conducting device is connected in parallel with inductor L1. After passing through the parallel unidirectional conducting device, the surge voltage is forward conducted, and the surge energy is absorbed by the energy storage capacitor, thereby ensuring that the internal components are not damaged by overvoltage. The unidirectional conducting characteristic of the diode does not affect the filtering function of inductor L1. It reduces EMI interference and provides surge protection. Moreover, the structure is simple and saves a lot of board space in the module design.
[0016] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A circuit that satisfies both EMI requirements and prevents surge high voltage damage to the internal capacitors of a module, comprising a PFC circuit, characterized in that: One end of the PFC circuit is connected to an input power supply, and the output end of the PFC circuit is connected to an inductor L1. Capacitors C1, C2, and C3 are connected at the junction between the PFC circuit and the inductor L1, respectively. Capacitors C1, C2, and C3 are all connected in parallel and grounded. A unidirectional conducting device is connected in parallel across the two ends of the inductor L1. Capacitor C4 is connected to the output end of the inductor L1, and capacitor C4 is connected in parallel with the inductor L1. The output end of the inductor L1 is connected to a base-collector voltage.
2. The circuit according to claim 1, which satisfies both EMI requirements and prevents surge high voltage damage to the internal capacitors of the module, is characterized in that: The unidirectional conducting device is a diode.
3. The circuit according to claim 1, which satisfies both EMI requirements and prevents surge high voltage damage to the internal capacitors of the module, is characterized in that: The unidirectional conducting device is a field-effect transistor.
4. The circuit according to claim 1 that satisfies both EMI requirements and prevents surge high voltage damage to the internal capacitors of the module, characterized in that: The unidirectional conducting device is a thyristor.