Circuit for suppressing surge current

Abstract

The utility model discloses a circuit for suppressing surge current. The circuit comprises a rectification output module, a filtering module, a surge suppression module, a boost module and a high-voltage capacitor output module. The first output end of the rectification output module is electrically connected with the filtering module, the output end of the filtering module is electrically connected with the boosting module, and the boosting module is electrically connected with the high-voltage capacitance output module; the second output end of the rectification output module is electrically connected with the surge suppression module, and the surge suppression module is electrically connected with the high-voltage capacitance output module.

Description

Technical Field

[0001] The utility model belongs to the technical field of electronic circuits, and particularly relates to a circuit for suppressing inrush current. Background Art

[0002] In order to prevent power grid pollution, in the field of switched-mode power supplies, mandatory harmonic test standards have been formulated for medium and high-power switched-mode power supplies in various countries. Therefore, in order to make the switched-mode power supply meet the harmonic test requirements, it is usually necessary to add a power factor correction (PFC) circuit at the front end of the switched-mode power supply.

[0003] PFC (Power Factor Correction), also known as power factor correction, mainly controls the waveform of the input current to make it synchronous with the input voltage waveform, improves the power factor, reduces the harmonic content, and can solve the electromagnetic interference and electromagnetic compatibility problems caused by the serious distortion of the current waveform due to capacitive loads.

[0004] In order to increase the PF value (power factor) of medium and high-power switched-mode power supplies and make the inrush current normal during startup, in common switched-mode power supply designs, a negative temperature coefficient thermistor (NTC) is connected in series at the input end of the main circuit to suppress the inrush current of the switched-mode power supply. However, this method has relatively large energy losses, resulting in low working efficiency and increased working temperature. Another solution is to connect a high-power resistor in series at the input main circuit end and connect a relay in parallel beside it. After the power supply starts and operates stably, the current no longer passes through this resistor, and the relay conducts to bypass this resistor, thereby suppressing the inrush current of the switched-mode power supply. However, this method has a high cost. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a circuit for suppressing inrush current to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the utility model provides the following technical solutions:

[0007] A circuit for suppressing inrush current includes a rectifier output module, a filtering module, an inrush current suppression module, a boosting module, and a high-voltage capacitor output module; the first output end of the rectifier output module is electrically connected to the filtering module, the output end of the filtering module is electrically connected to the boosting module, and the boosting module is electrically connected to the high-voltage capacitor output module; the second output end of the rectifier output module is electrically connected to the inrush current suppression module, and the inrush current suppression module is electrically connected to the high-voltage capacitor output module.

[0008] Preferably, the surge suppression module includes at least one resistor unit and a unidirectional diode. The second output terminal of the rectification output module is electrically connected to the resistor unit. The resistor unit is electrically connected to the first end of the unidirectional diode. The second end of the unidirectional diode is electrically connected to the input terminal of the high-voltage capacitor output module.

[0009] Preferably, the resistor unit of the surge suppression module is a thermistor.

[0010] Preferably, the filtering module includes a first capacitor, a second capacitor, and a first inductor. The first inductor is connected in series between the first output terminal of the rectification output module and the input terminal of the boost module. The first capacitor is connected in parallel between the first output terminal of the rectification output module and the intermediate node. The second capacitor is connected in parallel between the intermediate node and the input terminal of the boost module.

[0011] Preferably, the filtering module further includes a third capacitor, and the third capacitor is connected in parallel between the input terminal of the boost module and the intermediate node.

[0012] Preferably, the filtering module further includes a fuse resistor, and the fuse resistor is connected in parallel with the first inductor.

[0013] Preferably, the rectification output module includes a voltage input unit and a diode rectifier bridge. The output terminal of the voltage input unit is used to output alternating current. The voltage input unit is electrically connected to the input terminal of the diode rectifier bridge. The output terminal of the rectifier bridge is electrically connected to the input terminal of the filtering module.

[0014] Preferably, the boost module includes a second inductor and a boost diode. The first end of the second inductor is electrically connected to the output terminal of the filtering module. The second end of the second inductor is electrically connected to the first end of the boost diode. The second inductor and the boost diode are connected in series. The boost diode is electrically connected to the input terminal of the high-voltage capacitor output module.

[0015] Preferably, the high-voltage capacitor output module includes a plurality of capacitor units connected in parallel.

[0016] Advantages of the present utility model:

[0017] 1. In this application, the circuit for suppressing inrush current can suppress inrush current by providing a bypass path composed of a thermistor and a unidirectional diode.

[0018] 2. In this application, the circuit for suppressing inrush current uses a thermistor. As the thermistor operates, its resistance value decreases, reducing the energy consumed for heat dissipation and thus saving energy.

[0019] 3. In the present application, the circuit for suppressing inrush current adopts a first inductor. On the one hand, the inductor is relatively small to facilitate the passage of the DC part in the pulsed direct current, so as to complete the filtering function; on the other hand, when the power supply is turned on, the current cannot pass through instantaneously.

[0020] Other features and advantages of the present utility model will be described in detail in the subsequent specific implementation part. Brief Description of the Drawings

[0021] Figure 1 : Schematic flow diagram of the present utility model.

[0022] Figure 2 : Schematic circuit diagram of the present utility model.

[0023] Reference numerals in the drawings: 1, rectifier output module; 2, inrush current suppression module; 3, filtering module; 4, boost module; 5, high-voltage capacitor output module. Specific Embodiments

[0024] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model.

[0025] Please refer to Figure 1-2 ; The present application discloses a circuit for suppressing inrush current.

[0026] This embodiment provides a circuit for suppressing inrush current, including a rectifier output module 1, a filtering module 3, an inrush current suppression module 2, a boost module 4 and a high-voltage capacitor output module 5 to optimize the current distribution and suppress the inrush current.

[0027] Refer to Figure 1 , In this embodiment, the circuit for suppressing inrush current mainly has two charging paths:

[0028] The first path:

[0029] The rectifier output module 1 converts the input alternating current into pulsed direct current, and the pulsed direct current can pass through the inrush current suppression module 2 and finally reach the high-voltage capacitor output module 5 to charge the high-voltage capacitor output module 5;

[0030] The second path:

[0031] The rectifier output module 1 converts the input alternating current into pulsed direct current, and the pulsed direct current can pass through the filtering module 3, the boost module 4 and finally reach the high-voltage capacitor output module 5 to charge the high-voltage capacitor output module 5;

[0032] And because the filtering module 3 includes a first inductor and the boost module 4 includes a second inductor, the first charging path cannot pass current instantaneously when the power supply is turned on, effectively suppressing the inrush current.

[0033] Specifically, referring to Figure 2 , the rectifier output module 1 includes a voltage input unit and a diode rectifier bridge. The output terminal of the voltage input unit is used to output alternating current and is electrically connected to the input terminal of the diode rectifier bridge. Through the rectification of the diode rectifier bridge, the pulsed direct current rectified by the diode rectifier bridge can be output.

[0034] The first output terminal of the rectifier output module 1 is electrically connected to the filter module 3. The filter module 3 includes a first inductor, a first capacitor, a second capacitor, and a third capacitor. The first inductor is connected in series between the third output terminal of the diode rectifier bridge and the first terminal of the boost module 4. The first capacitor is connected in parallel between the third output terminal of the rectifier output module 1 and the intermediate node, the second capacitor is connected in parallel between the intermediate node and the first terminal of the boost module 4, the third capacitor is connected in parallel between the first terminal of the boost module 4 and the intermediate node, and the second capacitor and the third capacitor are connected in parallel.

[0035] When the circuit is operating normally, the pulsed current output from the diode rectifier bridge contains a direct current part and an alternating current part. Due to the large inductive reactance of the first inductor, it is difficult for the alternating current in the pulsed current output from the diode rectifier bridge to pass through, while the direct current in the pulsed current output from the diode rectifier bridge can pass through smoothly; the capacitive reactance of the first capacitor makes it difficult for the direct current part to pass through, while the alternating current part can pass through smoothly. Therefore, the first capacitor and the second capacitor can effectively eliminate the alternating current part in the pulsed current output from the diode rectifier bridge, that is, perform filtering. In order to further improve the filtering effect in the filter circuit and filter out the alternating current part, in this embodiment, the third capacitor can have a relatively large capacitance value. In addition, the filter module 3 further includes a fuse resistor, which is connected in parallel with the first inductor and is used to protect the first inductor and thus protect the circuit.

[0036] The input terminal of the boost module 4 is electrically connected to the output terminal of the filter module 3. The boost module 4 includes a second inductor and a boost diode. The first end of the second inductor is electrically connected to the second end of the first inductor, the second end of the second inductor is electrically connected to the first end of the boost diode, the second inductor and the boost diode are connected in series, and the other end of the boost diode is electrically connected to the input terminal of the high-voltage capacitor output module 5.

[0037] The high-voltage capacitor output module 5 includes a plurality of parallel-connected capacitor units for energy storage and voltage stabilization.

[0038] To suppress the inrush current, the second output terminal of the rectifier output module 1 is electrically connected to the inrush current suppression module 2. The inrush current suppression module 2 includes at least one resistance unit and a unidirectional diode. The second output terminal of the rectifier output module 1 is electrically connected to the resistance unit, the resistance unit is electrically connected to the first end of the unidirectional diode, and the second end of the unidirectional diode is electrically connected to the input terminal of the high-voltage capacitor output module 5. In a preferred embodiment, the resistance unit of the inrush current suppression module 2 is a thermistor (NTC) to effectively suppress the inrush current at the moment of power-on.

[0039] The specific working process is as follows:

[0040] When the power supply starts, the voltage input unit outputs alternating current, and the voltage of the alternating current is not limited. In this embodiment, the voltage of the output alternating current is 220V. The input alternating current is converted into pulsed direct current after passing through the diode rectifier bridge, forming two charging paths:

[0041] The first charging path:

[0042] The pulsed direct current after rectification directly charges the high-voltage capacitor through the thermistor TR1 (NTC) and the unidirectional diode D2.

[0043] Since there is no inductive element in this path, the current can be established quickly, so that at the moment of power-on, the high-voltage capacitor is charged prior to the second charging path.

[0044] The second charging path:

[0045] The direct current after rectification passes through the filter circuit composed of the first inductor L1. After filtering by the first capacitor, the second capacitor and the third capacitor, the high-frequency noise is further filtered out, effectively suppressing the electromagnetic interference from the input terminal to the output terminal, while maintaining a low insertion loss and good frequency response characteristics; then it passes through the second inductor L2 and the boost diode D1, and finally charges the high-voltage capacitor.

[0046] Since two inductive elements are connected in series in the second path, at the moment of power-on, the inductor current cannot change suddenly, so the current establishment speed is slower than that of the first charging path.

[0047] At the moment of power-on, since there is no inductive element in the first charging path, the current can quickly pass through the NTC resistor and the diode D2 to charge the high-voltage capacitor in advance, thereby suppressing the instantaneous large current impact. This pre-charging process significantly reduces the inrush current of the main PFC circuit. As the high-voltage capacitor is gradually charged to a certain voltage, the internal resistance of the main PFC circuit gradually decreases and begins to dominate the charging process.

[0048] When the device is powered on and enters the normal working state, since the internal resistance of the PFC main circuit in the second charging path is lower than that of the first charging path (NTC resistor path), and the output voltage generated after passing through the L1 π-type filter, L2 PFC inductor, and boost diode D1 in this path is higher than the DC voltage after the bridge rectifier, the first charging path will stop working. At this time, the current mainly passes through the second charging path, that is, the L1 π-type filter, L2 PFC inductor, and boost diode D1, and continues to charge the high-voltage capacitor.

[0049] This configuration not only realizes the efficient charging of the high-voltage capacitor, but also reduces the temperature rise during circuit operation and improves the overall working efficiency.

[0050] For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above-described exemplary embodiments, and the present utility model can be implemented in other specific forms without departing from the spirit or basic characteristics of the present utility model. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present utility model. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0051] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A circuit for suppressing surge current, characterized in that: It includes a rectifier output module, a filter module, a surge suppression module, a boost module and a high-voltage capacitor output module; the first output end of the rectifier output module is electrically connected to the filter module, the output end of the filter module is electrically connected to the boost module, and the boost module is electrically connected to the high-voltage capacitor output module; the second output end of the rectifier output module is electrically connected to the surge suppression module, and the surge suppression module is electrically connected to the high-voltage capacitor output module.

2. A circuit for suppressing surge current according to claim 1, characterized in that: The surge suppression module includes at least one resistance unit and a unidirectional diode, the second output end of the rectifier output module is electrically connected to the resistance unit, the resistance unit is electrically connected to the first end of the unidirectional diode, and the second end of the unidirectional diode is electrically connected to the input end of the high-voltage capacitor output module.

3. A circuit for suppressing surge current according to claim 2, characterized in that: The resistance unit of the surge suppression module is a thermistor.

4. The circuit for suppressing surge current according to claim 1, characterized in that: The filtering module includes a first capacitor, a second capacitor and a first inductor. The first inductor is connected in series between the first output end of the rectifier output module and the input end of the boost module. The first capacitor is connected in parallel between the first output end of the rectifier output module and the intermediate node; the second capacitor is connected in parallel between the intermediate node and the input end of the boost module.

5. A circuit for suppressing surge current according to claim 4, characterized in that: The filtering module further includes a third capacitor, and the third capacitor is connected in parallel between the input end of the boost module and the intermediate node.

6. The circuit for suppressing surge current according to claim 4, characterized in that: The filter module further includes a fuse resistor, and the fuse resistor is connected in parallel with the first inductor.

7. The circuit for suppressing surge current according to claim 1, characterized in that: The rectifier output module includes a voltage input unit and a diode rectifier bridge. The output end of the voltage input unit is used to output alternating current. The voltage input unit is electrically connected to the input end of the diode rectifier bridge. The output end of the rectifier bridge is electrically connected to the input end of the filter module.

8. The circuit for suppressing surge current according to claim 1, characterized in that: The boost module includes a second inductor and a boost diode, the first end of the second inductor is electrically connected to the output end of the filter module, the second end of the second inductor is electrically connected to the first end of the boost diode, the second inductor is connected in series with the boost diode, and the boost diode is electrically connected to the input end of the high-voltage capacitor output module. 9 . The circuit for suppressing surge current according to claim 1 , wherein the high-voltage capacitor output module comprises a plurality of capacitor units connected in parallel.

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