An AC input rectifier filter circuit

Abstract

This utility model relates to the field of rectifier and filter circuits, and more particularly to an AC input rectifier and filter circuit, including a rectifier bridge, a transformer, an anti-interference module, and an overvoltage protection module. A second safety Y capacitor CY2 and a third safety Y capacitor CY3 are connected in series. The third safety Y capacitor CY3 is connected to the N terminal of the mains power supply, and the second safety Y capacitor CY2 is connected to the L terminal of the mains power supply. The overvoltage protection module includes a varistor MOV1. The positive input terminal of a common-mode inductor L1 is connected to the L terminal of the mains power supply. The positive and negative output terminals of the common-mode inductor L1 are connected to the input terminals of the rectifier bridge, respectively. The positive output terminal of the rectifier bridge is connected to the positive terminal of a storage capacitor C3, and the negative output terminal of the rectifier bridge is connected to the negative terminal of the storage capacitor C3. The positive terminal of the storage capacitor C3 is connected to the transformer, and the transformer outputs 12V. This circuit enhances the anti-interference capability of the circuit by optimizing the design of the rectifier and filter circuit; at the same time, the introduction of overvoltage protection components such as a varistor improves the overvoltage protection capability of the circuit.

Description

Technical Field

[0001] This utility model relates to the field of rectifier and filter circuits, and more particularly to an AC input rectifier and filter circuit. Background Technology

[0002] In the field of power electronics, AC input rectifier and filter circuits, as a key component of power supply systems, bear the important task of converting alternating current (AC) into stable direct current (DC). However, existing AC input rectifier and filter circuits have some design shortcomings that affect their performance and reliability. First, existing rectifier and filter circuits lack sufficient anti-interference capabilities. During AC input, interference signals from the power grid (such as electromagnetic noise and surge voltage) can easily interfere with the circuit, affecting the rectification and filtering effect and potentially damaging components. This interference not only reduces the stability of the power supply system but may also adversely affect subsequent circuits. Second, existing rectifier and filter circuits are inadequate in overvoltage protection. In extreme situations such as abnormally high grid voltage or lightning strikes, without effective overvoltage protection measures, components in the circuit may be damaged by excessively high voltages. This can lead to power system failure and may also threaten equipment safety. Summary of the Invention

[0003] To address the aforementioned issues, this invention provides an AC input rectifier and filter circuit. This circuit enhances its anti-interference capability by optimizing the design of the rectifier and filter circuit; simultaneously, it incorporates overvoltage protection components such as varistors to improve the circuit's overvoltage protection capability.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is: an AC input rectifier and filter circuit, including a rectifier bridge, a transformer, an anti-interference module, and an overvoltage protection module. The anti-interference module includes a common-mode inductor L1, a second safety Y capacitor CY2, and a third safety Y capacitor CY3. The second safety Y capacitor CY2 and the third safety Y capacitor CY3 are connected in series. The third safety Y capacitor CY3 is connected to the N terminal of the mains power supply, and the second safety Y capacitor CY2 is connected to the L terminal of the mains power supply. The overvoltage protection module includes a varistor. MOV1, the two ends of the varistor MOV1 are connected to the L terminal of the mains power supply and the N terminal of the mains power supply, respectively. The positive input terminal of the common mode inductor L1 is connected to the L terminal of the mains power supply, and the negative input terminal of the common mode inductor L1 is connected to the N terminal of the mains power supply. The positive output terminal and the negative output terminal of the common mode inductor L1 are connected to the input terminal of the rectifier bridge, respectively. The positive output terminal of the rectifier bridge is connected to the positive terminal of the energy storage capacitor C3, and the negative output terminal of the rectifier bridge is connected to the negative terminal of the energy storage capacitor C3. The positive terminal of the energy storage capacitor C3 is connected to the transformer, and the output terminal of the transformer outputs 12V.

[0005] Furthermore, it also includes a discharge circuit, with a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The first resistor R1 and the second resistor R2 are connected in series, with the first resistor R1 connected to the L terminal of the mains power supply and the second resistor R2 connected to the N terminal of the mains power supply. The third resistor R3 and the fourth resistor R4 are connected in series, with the fourth resistor R4 connected to the L terminal of the mains power supply and the third resistor R3 connected to the N terminal of the mains power supply. The node between the first resistor R1 and the second resistor R2 is connected to the node between the third resistor R3 and the fourth resistor R4.

[0006] Furthermore, it also includes a protection circuit, which includes a first fuse F1, a second fuse F2, and a thermistor NTC1. The first fuse F1 and the second fuse F2 are both connected in series with the mains L terminal, and the node between the first fuse F1 and the second fuse F2 is connected to one end of the mains L terminal via a varistor MOV1. At the same time, the thermistor NTC1 is connected between the first fuse F1 and the first resistor R1.

[0007] Furthermore, the anti-interference module also includes a first safety Y capacitor CY1, one end of which is connected to the positive output of the rectifier bridge, and the other end of which is grounded.

[0008] Furthermore, it also includes a secondary clamping circuit, which includes a fourth capacitor C4, a fifth resistor R5, and a third diode D3. The positive terminal of the third diode D3 is connected to the negative terminal of the transformer's input, and the negative terminal of the third diode D3 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the positive output terminal of the rectifier bridge. At the same time, the negative terminal of the third diode D3 is also connected to the positive output terminal of the rectifier bridge through the fourth capacitor C4. The positive output terminal of the rectifier bridge is connected to the positive input terminal of the transformer.

[0009] Furthermore, it also includes a buffer circuit, a second diode D2, a first capacitor C1, and a sixth resistor R6. The positive output terminal of the transformer is connected to one end of the sixth resistor R6 through the first capacitor C1, and the other end of the sixth resistor R6 outputs 12V. At the same time, the positive output terminal of the transformer is connected to the positive terminal of the second diode D2, and the negative terminal of the second diode D2 is connected to the other end of the sixth resistor R6.

[0010] The beneficial effects of this utility model are as follows:

[0011] 1. By using a rectifier bridge, transformer, and energy storage capacitor in combination, effective rectification and filtering of AC power are achieved, resulting in a stable DC power output. Simultaneously, the safety capacitors and common-mode inductors in the anti-interference module further suppress interference components in the circuit, improving the filtering effect.

[0012] 2. The anti-interference module and overvoltage protection module in this utility model work together to effectively suppress electromagnetic interference and surge voltage in the circuit, enhance the electromagnetic compatibility of the circuit, and enable it to operate stably in various electromagnetic environments.

[0013] 3. The discharge circuit can quickly release residual charge in the circuit after power is cut off, avoiding safety hazards such as electric shock caused by charge accumulation. At the same time, the fuse and thermistor in the protection circuit can cut off the circuit in time when the current is too high, protecting circuit components from damage and improving the reliability and service life of the circuit.

[0014] 4. The AC input rectifier and filter circuit of this utility model is not only applicable to the switching power supply part in charging piles, but can also be widely used in other occasions that require AC / DC conversion, such as home appliances, industrial automation equipment and other fields, and has broad market prospects and application value. Attached Figure Description

[0015] Figure 1 This is a specific circuit diagram of an AC input rectifier and filter circuit. Detailed Implementation

[0016] Please see Figure 1 As shown, this utility model relates to an AC input rectifier and filter circuit, including a rectifier bridge, a transformer, an anti-interference module, and an overvoltage protection module. The anti-interference module includes a common-mode inductor L1, a second safety Y capacitor CY2, and a third safety Y capacitor CY3. The second safety Y capacitor CY2 and the third safety Y capacitor CY3 are connected in series. The third safety Y capacitor CY3 is connected to the N terminal of the mains power supply, and the second safety Y capacitor CY2 is connected to the L terminal of the mains power supply. The overvoltage protection module includes a varistor MOV1. The two ends of the sensitive resistor MOV1 are connected to the L terminal and the N terminal of the mains power supply, respectively. The positive input terminal of the common mode inductor L1 is connected to the L terminal of the mains power supply, and the negative input terminal of the common mode inductor L1 is connected to the N terminal of the mains power supply. The positive and negative output terminals of the common mode inductor L1 are connected to the input terminals of the rectifier bridge, the positive output terminal of the rectifier bridge is connected to the positive terminal of the energy storage capacitor C3, the negative output terminal of the rectifier bridge is connected to the negative terminal of the energy storage capacitor C3, and the positive terminal of the energy storage capacitor C3 is connected to the transformer. The output terminal of the transformer outputs 12V.

[0017] An AC input rectifier and filter circuit includes a rectifier bridge, a transformer, an anti-interference module, and an overvoltage protection module. The anti-interference module includes a common-mode inductor L1, a second safety Y capacitor CY2, and a third safety Y capacitor CY3. The second and third safety Y capacitors CY2 and CY3 are connected in series, with the third safety Y capacitor CY3 connected to the N terminal of the mains power supply, and the second safety Y capacitor CY2 connected to the L terminal of the mains power supply. The overvoltage protection module includes a varistor MOV1, with its two ends connected to the L and N terminals of the mains power supply, respectively. The positive input terminal of the common-mode inductor L1 is connected to the L terminal of the mains power supply, and the negative input terminal of the common-mode inductor L1 is connected to the N terminal of the mains power supply. The positive and negative output terminals of the common-mode inductor L1 are connected to the input terminals of the rectifier bridge, the positive output terminal of the rectifier bridge is connected to the positive terminal of a storage capacitor C3, and the negative output terminal of the rectifier bridge is connected to the negative terminal of the storage capacitor C3. The positive terminal of the storage capacitor C3 is connected to the transformer, and the transformer outputs 12V.

[0018] The mains power (220V AC) first passes through an interference suppression module. This module consists of a common-mode inductor L1 and two safety-certified Y capacitors (CY2 and CY3). CY2 and CY3 are connected in series, connected to the L (live) and N (neutral) terminals of the mains power supply, respectively. Their function is to suppress common-mode interference signals from the mains power supply, which may be caused by other equipment in the power grid or natural phenomena (such as lightning). The common-mode inductor L1 is also connected between the L and N terminals of the mains power supply. It utilizes the impedance characteristics of inductance to AC power to further suppress common-mode interference signals, ensuring a cleaner current entering subsequent circuits. After being processed by the interference suppression module, the mains power enters the rectifier bridge. The rectifier bridge is a bridge structure composed of four diodes, and its function is to convert AC power to DC power. During the positive half-cycle of the mains power, two diodes in the rectifier bridge conduct, directing current from the L terminal through the bridge to the positive terminal of the storage capacitor C3. During the negative half-cycle, the other two diodes conduct, directing current from the N terminal through the bridge to the positive terminal of the storage capacitor C3 (actually, the current flows out through the negative terminal of the bridge, but effectively charges the positive terminal of C3). In this way, the rectifier bridge converts AC to DC. The output of the rectifier bridge is connected to the storage capacitor C3. The function of C3 is to smooth the rectified DC, reducing voltage fluctuations. Because the rectified DC still has a certain pulsating component, C3 can charge and discharge to smooth these fluctuations, making the output voltage more stable. The smoothed DC then enters the transformer for voltage reduction. The transformer uses the principle of electromagnetic induction to convert the high-voltage DC to the required low-voltage DC (12V in this example). The output of the transformer is connected to subsequent circuits, providing them with a stable 12V DC power supply.

[0019] The circuit also includes an overvoltage protection module, consisting of a varistor MOV1. MOV1 is a resistor with non-linear volt-ampere characteristics; when the voltage in the circuit exceeds its rated value, its resistance decreases rapidly, thus limiting the current in the circuit. When an overvoltage condition occurs (such as a sudden increase in mains voltage), MOV1 responds quickly, absorbing the overvoltage energy and converting it into heat, thereby protecting the circuit components from damage.

[0020] Furthermore, it also includes a discharge circuit, with a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The first resistor R1 and the second resistor R2 are connected in series, with the first resistor R1 connected to the L terminal and the second resistor R2 connected to the N terminal. The third resistor R3 and the fourth resistor R4 are connected in series, with the fourth resistor R4 connected to the L terminal and the third resistor R3 connected to the N terminal. The node between the first resistor R1 and the second resistor R2 is connected to the node between the third resistor R3 and the fourth resistor R4.

[0021] Working principle: This discharge circuit consists of a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4, connected as follows: The first resistor R1 and the second resistor R2 are connected in series. One end of the first resistor R1 is connected to the L terminal of the mains power supply, and one end of the second resistor R2 is connected to the N terminal of the mains power supply. The third resistor R3 and the fourth resistor R4 are also connected in series, but in the opposite manner to R1 and R2; that is, one end of the fourth resistor R4 is connected to the L terminal of the mains power supply, and one end of the third resistor R3 is connected to the N terminal of the mains power supply. The node between the first resistor R1 and the second resistor R2 is connected to the node between the third resistor R3 and the fourth resistor R4, forming a discharge loop.

[0022] When the circuit is operating normally, the mains power is rectified and filtered by components such as the rectifier bridge to provide DC power to subsequent circuits. At this time, the resistor in the discharge circuit mainly serves to limit current and divide voltage, having little impact on the normal operation of the circuit. However, when the circuit is powered off or the mains power suddenly disappears, the storage capacitor C3 still stores a large amount of charge. Without the discharge circuit, this charge may remain in the capacitor for a long time, potentially even forming a dangerous high voltage. The discharge circuit exists to provide a discharge path after the circuit is powered off, allowing the charge in the storage capacitor C3 to be released quickly. Specifically, when the circuit is powered off, the storage capacitor C3 begins to discharge through the discharge circuit. Current flows from the positive terminal of capacitor C3, passes through the resistor in the discharge circuit, and finally flows back to the negative terminal of capacitor C3. Due to the presence of the resistor, the discharge process is not instantaneous but requires a certain amount of time. However, this method ensures that the charge in the capacitor is completely released within a safe time.

[0023] The presence of a discharge circuit ensures that the charge in the storage capacitor is released quickly and safely after power is cut off. This avoids potential hazards to personnel or equipment from residual high voltage in the capacitor. Charge remaining in the capacitor for a long time can damage the capacitor itself or other components in the circuit. Timely release of this charge through the discharge circuit can extend the lifespan of the equipment.

[0024] Furthermore, it also includes a protection circuit, which includes a first fuse F1, a second fuse F2, and a thermistor NTC1. The first fuse F1 and the second fuse F2 are both connected in series with the L terminal, and the node between the first fuse F1 and the second fuse F2 is connected to one end of the L terminal with the varistor MOV1. At the same time, the thermistor NTC1 is connected between the first fuse F1 and the first resistor R1.

[0025] Both fuses F1 and F2 are connected in series with the L terminal of the mains power supply, serving as overcurrent protection devices in the circuit. When an overcurrent or short circuit occurs, the fuses will melt due to excessive current, thus cutting off the circuit and preventing equipment damage or fires. The junction between fuses F1 and F2 is connected to one end of the L terminal of a varistor MOV1. The varistor MOV1 suppresses overvoltages in the circuit. When the voltage exceeds its rated value, MOV1 quickly conducts, absorbing the overvoltage energy and dissipating it as heat. If the overvoltage lasts for a long time or has a large energy, it may cause a sharp increase in the current in the circuit. In this case, fuse F1 or F2 will melt, further protecting the circuit and equipment.

[0026] The thermistor NTC1 is connected between the first fuse F1 and the first resistor R1. NTC1 is a negative temperature coefficient thermistor, meaning its resistance decreases as temperature increases. When the circuit is first powered on, the current flowing through NTC1 generates heat, temporarily lowering its resistance and limiting the inrush current during startup. As the circuit stabilizes, the temperature of NTC1 gradually decreases, and its resistance returns to normal, having minimal impact on the normal operation of the circuit.

[0027] The combined use of fuses and varistors effectively prevents overcurrent, short circuits, and overvoltage in the circuit, improving circuit safety. The current-limiting function of the thermistor reduces inrush current during circuit startup, further protecting the circuit and equipment. As a one-time protective component, the fuse quickly melts and disconnects the circuit when a fault occurs, preventing the fault from escalating. The addition of varistors and thermistors ensures that the circuit maintains high reliability under various abnormal conditions.

[0028] Furthermore, the anti-interference module also includes a first safety Y capacitor CY1, one end of which is connected to the positive output of the rectifier bridge, and the other end of which is grounded.

[0029] The common-mode inductor L1, along with the second safety Y capacitor CY2 and the third safety Y capacitor CY3, are connected in series to suppress common-mode interference from the mains power. The common-mode inductor utilizes the impedance characteristics of inductance to AC current, while the Y capacitors provide a low-impedance path to guide the common-mode interference current to ground, effectively reducing the impact of common-mode interference on the circuit. One end of the first safety Y capacitor CY1 is connected to the positive output terminal of the rectifier bridge, and the other end is grounded. This connection method helps suppress differential-mode interference. Differential-mode interference is an interference signal existing between the phase line (live wire L) and the neutral line (neutral wire N) of the circuit. When the positive output terminal of the rectifier bridge (i.e., the positive terminal of the DC power supply) is grounded through CY1, CY1 provides a low-impedance path to ground for differential-mode interference, thereby reducing the impact of differential-mode interference on subsequent circuits. Through the combined use of the common-mode inductor L1, Y capacitors CY2 and CY3, and CY1, the anti-interference module can comprehensively suppress both common-mode and differential-mode interference from the mains power, ensuring a cleaner current entering subsequent circuits.

[0030] Furthermore, it also includes a secondary clamping circuit, which includes a fourth capacitor C4, a fifth resistor R5, and a third diode D3. The positive terminal of the third diode D3 is connected to the negative terminal of the transformer's input, and the negative terminal of the third diode D3 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the positive output terminal of the rectifier bridge. At the same time, the negative terminal of the third diode D3 is also connected to the positive output terminal of the rectifier bridge through the fourth capacitor C4. The positive output terminal of the rectifier bridge is connected to the positive input terminal of the transformer.

[0031] When the rectifier bridge outputs a positive voltage, the third diode D3 is in reverse cutoff because its positive terminal potential is lower than its negative terminal potential. Under normal operating conditions, the DC voltage output by the rectifier bridge supplies power to the transformer through the positive input terminal. However, when transient overvoltages or surge voltages occur in the circuit, these high voltages may generate back electromotive force through the transformer's leakage inductance or other parasitic inductances, attempting to pull down the voltage or cause oscillations. At this time, the secondary clamping circuit comes into play. The fourth capacitor C4, as an energy storage element, can absorb part of the energy from this transient overvoltage. Simultaneously, the fifth resistor R5, combined with the third diode D3, forms a discharge circuit. When the transient overvoltage disappears, the charge stored in C4 discharges through R5 and D3, ensuring the circuit quickly returns to normal operating conditions. The forward conduction characteristic of D3 allows for a discharge path when needed, while R5 limits the magnitude of the discharge current, preventing damage to the circuit.

[0032] Furthermore, it also includes a buffer circuit, a second diode D2, a first capacitor C1, and a sixth resistor R6. The positive output terminal of the transformer is connected to one end of the sixth resistor R6 through the first capacitor C1, and the other end of the sixth resistor R6 outputs 12V. At the same time, the positive output terminal of the transformer is connected to the positive terminal of the second diode D2, and the negative terminal of the second diode D2 is connected to the other end of the sixth resistor R6.

[0033] When the transformer outputs a positive voltage, current flows through the first capacitor C1 to the sixth resistor R6, providing a stable 12V voltage to the subsequent circuits. The first capacitor C1 acts as an energy storage and filter, smoothing voltage fluctuations at the transformer output and ensuring output voltage stability. The second diode D2 provides reverse protection. When a transient reverse voltage occurs at the transformer output, D2 quickly conducts, short-circuiting the reverse voltage to ground, thus protecting the subsequent circuits from reverse voltage impacts. The sixth resistor R6 acts as a current-limiting resistor, limiting the current flowing through the circuit to prevent excessive current from damaging it.

[0034] The above embodiments are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made to the technical solutions of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. An AC input rectifier filter circuit, characterized by: The system includes a rectifier bridge, transformer, anti-interference module, and overvoltage protection module. The anti-interference module comprises a common-mode inductor (L1), a second safety Y-capacitor (CY2), and a third safety Y-capacitor (CY3). The second and third safety Y-capacitors (CY2 and CY3) are connected in series, with the third safety Y-capacitor (CY3) connected to the neutral (N) terminal of the mains power supply, and the second safety Y-capacitor (CY2) connected to the low (L) terminal of the mains power supply. The overvoltage protection module includes a varistor (MOV1). The varistor (MOV1)... The two ends are connected to the L terminal and N terminal of the mains power supply, respectively. The positive input terminal of the common mode inductor (L1) is connected to the L terminal of the mains power supply, and the negative input terminal of the common mode inductor (L1) is connected to the N terminal of the mains power supply. The positive output terminal and the negative output terminal of the common mode inductor (L1) are connected to the input terminal of the rectifier bridge, respectively. The positive output terminal of the rectifier bridge is connected to the positive terminal of the energy storage capacitor (C3), and the negative output terminal of the rectifier bridge is connected to the negative terminal of the energy storage capacitor (C3). The positive terminal of the energy storage capacitor (C3) is connected to the transformer, and the output terminal of the transformer outputs 12V.

2. An AC input rectifier filter circuit as claimed in claim 1, characterized in that: It also includes a discharge circuit, a first resistor (R1), a second resistor (R2), a third resistor (R3), and a fourth resistor (R4). The first resistor (R1) and the second resistor (R2) are connected in series, with the first resistor (R1) connected to the L terminal of the mains power supply and the second resistor (R2) connected to the N terminal of the mains power supply. The third resistor (R3) and the fourth resistor (R4) are connected in series, with the fourth resistor (R4) connected to the L terminal of the mains power supply and the third resistor (R3) connected to the N terminal of the mains power supply. The node between the first resistor (R1) and the second resistor (R2) is connected to the node between the third resistor (R3) and the fourth resistor (R4).

3. An AC input rectifier filter circuit as claimed in claim 2, characterized in that: It also includes a protection circuit, which includes a first fuse (F1), a second fuse (F2), and a thermistor (NTC1). The first fuse (F1) and the second fuse (F2) are both connected in series with the mains L terminal, and the node between the first fuse (F1) and the second fuse (F2) is connected to one end of the mains L terminal via a varistor (MOV1). At the same time, the thermistor (NTC1) is connected between the first fuse (F1) and the first resistor (R1).

4. An AC input rectifier filter circuit as claimed in claim 3, characterized in that: The anti-interference module also includes a first safety Y capacitor (CY1), one end of which is connected to the positive output of the rectifier bridge, and the other end of which is grounded.

5. An AC input rectifier filter circuit as claimed in claim 4, characterized in that: It also includes a secondary clamping circuit, which consists of a fourth capacitor (C4), a fifth resistor (R5), and a third diode (D3). The positive terminal of the third diode (D3) is connected to the negative terminal of the transformer's input, and the negative terminal of the third diode (D3) is connected to one end of the fifth resistor (R5). The other end of the fifth resistor (R5) is connected to the positive output terminal of the rectifier bridge. At the same time, the negative terminal of the third diode (D3) is also connected to the positive output terminal of the rectifier bridge through the fourth capacitor (C4). The positive output terminal of the rectifier bridge is connected to the positive input terminal of the transformer.

6. An AC input rectifier filter circuit as claimed in claim 5, characterized in that: It also includes a buffer circuit, a second diode (D2), a first capacitor (C1), and a sixth resistor (R6). The positive output terminal of the transformer is connected to one end of the sixth resistor (R6) through the first capacitor (C1), and the other end of the sixth resistor (R6) outputs 12V. At the same time, the positive output terminal of the transformer is connected to the positive terminal of the second diode (D2), and the negative terminal of the second diode (D2) is connected to the other end of the sixth resistor (R6).

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