Switching power supply and switching power supply circuit thereof

Abstract

The utility model provides a switching power supply and switching power supply circuit thereof, wherein the circuit comprises: input surge protection circuit; high voltage rectifier circuit is connected with input surge protection circuit and has high voltage rectifier diode for converting alternating current input into high voltage pulsating direct current; power conversion circuit is connected with high voltage rectifier circuit and is used for converting high voltage pulsating direct current into high frequency low voltage pulse electricity; output rectification filter circuit is connected with power conversion circuit; EMC filter circuit is connected with power conversion circuit at one end and is connected with output rectification filter circuit at the other end; further comprising: diode static protection circuit is connected in parallel at both ends of high voltage rectifier circuit; diode static protection circuit and EMC filter circuit, input surge protection circuit jointly constitute static discharge path and are used for limiting and reducing the static voltage applied at both ends, the utility model discloses effectively limit and reduce the static voltage at both ends of high voltage rectifier diode, promote the anti static ability and reliability of power supply system.

Description

Technical Field

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

[0002] In the switching power supply of devices such as electricity meters, the AC input is rectified by a high-voltage rectifier diode and converted into high-voltage DC power. Then, it is converted into low-voltage DC power by a power conversion circuit and a transformer. To meet electromagnetic compatibility requirements, a Y capacitor is usually connected between the primary and secondary sides.

[0003] However, when the secondary side or auxiliary terminals are subjected to electrostatic discharge (ESD), the static electricity can be transferred to the primary side high-voltage rectifier diodes through the transformer or Y capacitor. If the ESD level is high or the diode's ESD immunity is insufficient, it can easily lead to diode breakdown, thereby causing power supply failure. In the existing technology, high-voltage rectifier diodes rely solely on their own ESD immunity to "harden" against ESD shocks, lacking an effective protective structure and thus exhibiting insufficient reliability. Utility Model Content

[0004] To address the shortcomings of existing technologies, one of the objectives of this application is to provide a switching power supply circuit that effectively limits and reduces the electrostatic voltage across the high-voltage rectifier diode, thereby improving the anti-static capability and reliability of the power supply system.

[0005] A switching power supply circuit, comprising:

[0006] Input surge protection circuit;

[0007] A high-voltage rectifier circuit is connected to the input surge protection circuit and has a high-voltage rectifier diode for converting AC input into high-voltage pulsating DC current.

[0008] A power conversion circuit, connected to the high-voltage rectifier circuit, is used to convert the high-voltage pulsating DC power into high-frequency low-voltage pulsed power.

[0009] An output rectifier and filter circuit, connected to the power conversion circuit, is used to rectify the high-frequency low-voltage pulse electricity into low-voltage DC electricity.

[0010] An EMC filter circuit, one end of which is connected to the power conversion circuit, and the other end of which is connected to the output rectifier filter circuit; further comprising:

[0011] A diode electrostatic discharge (ESD) protection circuit is connected in parallel across the high-voltage rectifier circuit. The diode ESD protection circuit, together with the EMC filter circuit and the input surge protection circuit, forms an ESD discharge path to limit and reduce the ESD voltage applied across the two ends.

[0012] Preferably, the diode electrostatic discharge protection circuit includes a capacitor CY2, which is connected in parallel across at least one high-voltage rectifier diode in the high-voltage rectifier circuit.

[0013] Preferably, the input surge protection circuit includes multiple varistors, which are respectively connected between the AC input lines.

[0014] Preferably, the high-voltage rectifier circuit includes a plurality of high-voltage rectifier diodes.

[0015] Preferably, the power conversion circuit includes a capacitor C1, a high-frequency transformer T1, and a PWM power conversion circuit. The capacitor C1 is used to convert the high-voltage pulsating DC power from the rectifiers D1 to D3 into a stable high-voltage DC power. The PWM power conversion circuit is used to convert the high-voltage DC power on C1 into high-frequency high-voltage pulse power and then into high-frequency low-voltage pulse power through the high-frequency transformer T1, which is then transmitted to the secondary side.

[0016] Preferably, the output rectifier and filter circuit includes a low-voltage rectifier diode and a filter capacitor for outputting a stable low-voltage DC power.

[0017] This utility model also discloses a switching power supply, which includes the switching power supply circuit described in any of the above technical solutions.

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

[0019] This invention, by adding a diode electrostatic protection circuit and combining it with the original circuit structure, constructs an electrostatic discharge path, effectively limiting and reducing the electrostatic voltage across the high-voltage rectifier diode, thereby improving the anti-static capability and reliability of the power supply system. Attached Figure Description

[0020] Figure 1 This is a connection diagram for a switching power supply circuit. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] Example:

[0023] A switching power supply circuit, such as Figure 1 As shown, it includes:

[0024] Input surge protection circuit: Includes varistors MOV1, MOV2, and MOV3. Varistor MOV1 is connected to AC input terminals L1 and L2; MOV2 is connected to AC input terminals L2 and L3; and MOV3 is connected to AC input terminal L3 and the neutral terminal N. Varistors MOV1, MOV2, and MOV3 function as surge voltage protection devices, effectively reducing surge voltage impacts at AC input terminals L1, L2, L3, and N.

[0025] High-voltage rectifier circuit: It has high-voltage rectifier diodes D1, D2, and D3. The anode of D1 is connected to the AC input terminal L1 and one end of MOV1, and the cathode is connected to the downstream power conversion circuit. The anode of D2 is connected to the AC input terminal L2 and one end of MOV1 and MOV2, and the cathode is connected to the downstream power conversion circuit. The anode of D3 is connected to the AC input terminal L3 and one end of MOV2 and MOV3, and the cathode is connected to the downstream power conversion circuit. The high-voltage rectifier diodes D1 to D3 convert the AC input into high-voltage pulsating DC power.

[0026] Power conversion circuit: It has capacitor C1, high-frequency transformer T1 and PWM power conversion circuit. The capacitor C1 is connected to the output terminal of the high-voltage rectifier circuit, that is, the cathode of the high-voltage rectifier diodes D1, D2 and D3, which converts the high-voltage pulsating DC current from D1~D3 into stable high-voltage DC current. The input terminal of the PWM power conversion circuit is connected to both ends of the capacitor C1 (i.e. the positive and negative terminals of the high-voltage DC current), and the output terminal is connected to the primary winding of the high-frequency transformer T1. The PWM power conversion circuit converts the high-voltage DC current on C1 into high-frequency high-voltage pulse current, and then converts it into high-frequency low-voltage pulse current through the high-frequency transformer T1 and transmits it to the secondary side.

[0027] Output rectifier and filter circuit: It has a low-voltage diode D4 and a capacitor C2. The anode of the low-voltage diode D4 is connected to the secondary winding of the high-frequency transformer T1. The low-voltage diode D4 rectifies the high-frequency low-voltage pulse current transmitted from the high-frequency transformer T1. The cathode of the low-voltage diode D4 is connected to the positive terminal of the capacitor C2 and serves as the output terminal (Vout) to provide a stable low-voltage DC current to the downstream load (such as the electricity meter system). The negative terminal of the capacitor C2 is connected to the secondary side grounding network (GND), forming a complete filtering and power supply circuit.

[0028] EMC filter circuit: It has a capacitor CY1. One end of the capacitor CY1 is connected to the DC+ network of the primary power conversion circuit, and the other end is connected to the GND network of the secondary output rectifier filter circuit. The EMC filter circuit can filter out high-frequency noise.

[0029] The above is a simplified description of existing technologies.

[0030] It also includes: a diode electrostatic discharge protection circuit: having a capacitor CY2 connected in parallel across at least one high-voltage rectifier diode in the high-voltage rectifier circuit.

[0031] In the aforementioned switching power supply circuit, when there is high electrostatic interference in the secondary weak current Vout network or GND network, because the AC potential of L1 / L2 / L3 / N on the primary side is relatively low, CY1 will bypass the electrostatic discharge to the DC+ network on the primary side. The electrostatic voltage potential of the DC+ network will increase, and the electrostatic discharge will be applied to the cathodes of the high-voltage rectifier diodes D1, D2, and D3, as well as one end of CY2 in the diode electrostatic protection circuit. At this time, the "diode electrostatic protection circuit", "input surge protection circuit", and "EMC filter circuit" together form an electrostatic discharge path, suppressing and significantly reducing the electrostatic voltage level from the cathode to the anode of the high-voltage rectifier diodes D1, D2, and D3, thereby improving the anti-static capability of the high-voltage rectifier diodes.

[0032] To further illustrate the principle of this utility model and facilitate understanding, the secondary side is set to withstand a relatively high electrostatic charge of 8kV. The potentials of AC currents L1, L2, L3, and N relative to the 8kV electrostatic charge are 0V, and the varistor voltage parameter is 470V. These values ​​are set here solely for ease of understanding the circuit principle of this utility model. Therefore:

[0033] CY2 is connected in parallel across the high-voltage rectifier diode D1 and in series with CY1, connected to L1. When an 8kV electrostatic discharge is applied to the output Vout or GND network on the secondary side, the electrostatic discharge across D1 will be bypassed to L1 by CY2. Furthermore, due to the series connection of CY1 and CY2, the electrostatic voltage level across D1 is limited to [value missing]. .

[0034] CY2 and MOV1 are connected in series and then in parallel across the high-voltage rectifier diode D2, and in series with CY1, connected to L2. When an 8kV electrostatic discharge is applied to the output Vout or GND network on the secondary side, the electrostatic discharge across D2 will be bypassed to L2 by CY2 and the varistor MOV1. Due to its device characteristics, the voltage across the varistor will be limited to the varistor voltage value when a high voltage is present. Simultaneously, due to the series connection of CY1 and CY2, the electrostatic voltage level across D2 is limited to... .

[0035] CY2 and MOV2 are connected in series and then in parallel across the high-voltage rectifier diode D3, and in series with CY1, connected to L3. When an 8kV electrostatic discharge is applied to the output Vout or GND network on the secondary side, the electrostatic discharge across D2 will be bypassed to L3 by CY2 and the varistor MOV1. Due to its device characteristics, the voltage across the varistor will be limited to the varistor voltage value when a high voltage is present. Simultaneously, due to the series connection of CY1 and CY2, the electrostatic voltage level across D3 is limited to... .

[0036] As can be seen, based on the electrostatic voltage levels across D1, D2, and D3, by setting the capacitance ratio of CY1 to CY2, the electrostatic voltage levels across the high-voltage rectifier diodes D1, D2, and D3 can be limited, making their electrostatic voltage levels much lower than the diodes' inherent electrostatic discharge (ESD) capability. This improves the ESD capability of the high-voltage rectifier diodes and reduces the risk of circuit failure. For ease of understanding, assuming CY2 = 2CY1, the ESD level across D1 is limited to 2 / 3 * 8kV = 5.33kV, and the ESD levels across D2 and D3 are limited to 2 / 3 * 8kV + 470V = 5.8kV. Therefore, the actual ESD voltage experienced by D1, D2, and D3 is less than 8kV, far below the diodes' breakdown threshold, thus improving their ESD capability.

[0037] Furthermore, since both capacitors CY1 and CY2 are adjustable capacitors, the capacitance ratio of capacitors CY1 and CY2 can be directly adjusted without replacing capacitors CY1 and CY2, thus conveniently adjusting the required electrostatic discharge limiting voltage value.

[0038] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the design concept of the present invention should fall within the protection scope of the present invention. The technical content for which protection is sought in the present invention has been fully described in the claims.

Claims

1. A switching power supply circuit, comprising: Input surge protection circuit; A high-voltage rectifier circuit is connected to the input surge protection circuit and has a high-voltage rectifier diode for converting AC input into high-voltage pulsating DC current. A power conversion circuit, connected to the high-voltage rectifier circuit, is used to convert the high-voltage pulsating DC power into high-frequency low-voltage pulsed power. An output rectifier and filter circuit, connected to the power conversion circuit, is used to rectify the high-frequency low-voltage pulse electricity into low-voltage DC electricity. An EMC filter circuit, one end of which is connected to the power conversion circuit, and the other end of which is connected to the output rectifier filter circuit; characterized in that it further includes: A diode electrostatic discharge (ESD) protection circuit is connected in parallel across the high-voltage rectifier circuit. The diode ESD protection circuit, together with the EMC filter circuit and the input surge protection circuit, forms an ESD discharge path to limit and reduce the ESD voltage applied across the two ends.

2. The switching power supply circuit according to claim 1, characterized in that, The diode electrostatic discharge protection circuit includes a capacitor CY2, which is connected in parallel across at least one high-voltage rectifier diode in the high-voltage rectifier circuit.

3. The switching power supply circuit according to claim 1, characterized in that, The input surge protection circuit includes multiple varistors, which are connected between the AC input lines respectively.

4. A switching power supply circuit according to claim 1, characterized in that, The high-voltage rectifier circuit includes multiple high-voltage rectifier diodes.

5. A switching power supply circuit according to claim 1, characterized in that, The power conversion circuit includes a capacitor C1, a high-frequency transformer T1, and a PWM power conversion circuit. The capacitor C1 is used to convert the high-voltage pulsating DC power into a stable high-voltage DC power. The PWM power conversion circuit is used to convert the high-voltage DC power on C1 into high-frequency high-voltage pulse power and then into high-frequency low-voltage pulse power through the high-frequency transformer T1, which is then transmitted to the secondary side.

6. A switching power supply circuit according to claim 1, characterized in that, The output rectifier and filter circuit includes a low-voltage rectifier diode and a filter capacitor, which are used to output a stable low-voltage DC power.

7. A switching power supply, characterized in that, It includes the switching power supply circuit described in any one of claims 1 to 6.

Images