A reverse voltage ringing elimination circuit

Abstract

The utility model relates to the field of power electronics, especially a kind of elimination circuit of reverse voltage ringing, the same name end of the first winding of mutual inductor L and the different name end of the second winding of ringing elimination module's anode are all electrically connected with the output end anode of synchronous rectification module, and the different name end of the first winding of mutual inductor L is used as the output end anode of elimination circuit;The same name end of the second winding of mutual inductor L and the control end of ringing elimination module are electrically connected;The cathode of ringing elimination module is electrically connected with the output end cathode of synchronous rectification module, and is used as the output end cathode of elimination circuit;When the MOS tube of synchronous rectification module is turned off, mutual inductor L drives ringing elimination module to turn off, and ringing elimination module absorbs reverse voltage ringing;Solve the problem that reverse voltage ringing is generated when synchronous rectification module is turned off, leading to the serious problem of EMI electromagnetic interference of circuit.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and in particular to a circuit for eliminating reverse voltage ringing. Background Technology

[0002] In a power supply circuit, after power-on, the secondary winding of the transformer outputs high-frequency AC power to the rectifier module. The rectifier module converts the high-frequency AC power into DC pulse voltage, which is then transmitted to subsequent circuits or loads. However, the rectifier module is usually composed of MOSFETs forming a synchronous rectifier module. When the MOSFETs are turned off, due to their own and the parasitic parameters in the circuit, reverse (spike) voltage ringing is generated, resulting in severe EMI electromagnetic interference in the circuit. Utility Model Content

[0003] To address the aforementioned shortcomings, the purpose of this invention is to propose a reverse voltage ringing elimination circuit to solve the problem of severe EMI electromagnetic interference caused by reverse voltage ringing when the synchronous rectifier module is turned off.

[0004] To achieve this objective, the present invention adopts the following technical solution: A reverse voltage ringing elimination circuit includes a current transformer L1 and a ringing elimination module; the positive terminal of the ringing elimination module, the same-name terminal of the first winding and the opposite-name terminal of the second winding of the current transformer L1 are all electrically connected to the positive terminal of the output terminal of the synchronous rectification module, and the opposite-name terminal of the first winding of the current transformer L1 is used as the positive terminal of the output terminal of the elimination circuit. The same-name terminal of the second winding of the current transformer L1 is electrically connected to the control terminal of the ringing elimination module. The negative terminal of the ringing cancellation module is electrically connected to the negative terminal of the output terminal of the synchronous rectification module, and the negative terminal of the ringing cancellation module is used as the negative terminal of the output terminal of the cancellation circuit. When the MOSFET of the synchronous rectification module is turned off, the current transformer L1 drives the ringing elimination module to turn off, and the ringing elimination module absorbs reverse voltage ringing. When the MOS transistor of the synchronous rectification module is turned on, the current transformer L1 drives the ringing elimination module to turn on, and the ringing elimination module provides power to the output terminal of the synchronous rectification module.

[0005] Furthermore, it also includes a frequency selection module; the same-name terminal of the second winding of the current transformer L1 is electrically connected to the control terminal of the ringing elimination module via the frequency selection module.

[0006] Furthermore, the ringing cancellation module includes a MOSFET Q1 and a capacitor C1; the source of the MOSFET Q1 is used as the positive terminal of the ringing cancellation module, the gate of the MOSFET Q1 is used as the control terminal of the ringing cancellation module, one end of the capacitor C1 is used as the negative terminal of the ringing cancellation module; the drain of the MOSFET Q1 and the other end of the capacitor C1 are electrically connected. When the MOS transistor Q1 is turned off, the ringing cancellation module is turned off; When the MOS transistor Q1 is turned on, the ringing cancellation module is turned on.

[0007] Furthermore, the ringing cancellation module also includes a resistor R1 and a Zener diode D1; the resistor R1 is connected in parallel between the source and gate of the MOS transistor Q1, and the anode and cathode of the Zener diode D1 are electrically connected to the source and gate of the MOS transistor Q1, respectively.

[0008] Furthermore, the frequency selection module includes a resistor R2 and a capacitor C2; the same-name terminal of the second winding of the current transformer L1 is connected in series with the capacitor C2 and the resistor R2, and then electrically connected to the control terminal of the ringing elimination module.

[0009] Furthermore, it also includes a capacitor EC1; the positive terminal of the capacitor EC1 is electrically connected to the opposite terminal of the first winding of the current transformer L1, and the negative terminal of the capacitor EC1 is electrically connected to the negative terminal of the ringing elimination module.

[0010] The technical solution provided by this utility model can include the following beneficial effects: the first winding of the current transformer L1 automatically senses the DC pulse voltage output by the synchronous rectification module (the DC pulse voltage changes with the MOS transistor of the synchronous rectification module being turned off or on), and the second winding of the current transformer L1 will generate an induced voltage through mutual inductance with the first winding, thereby controlling the ringing elimination module to follow the MOS transistor of the synchronous rectification module to be turned off or on, so as to absorb reverse voltage ringing when the MOS transistor of the synchronous rectification module is turned off, thereby achieving the purpose of eliminating reverse voltage ringing. When the MOS transistor of the synchronous rectification module is turned on, it provides power to the output terminal of the synchronous rectification module, thereby improving the efficiency of the application circuit (i.e., the circuit connected to the output terminal of the elimination circuit). Attached Figure Description

[0011] Figure 1 This is a circuit diagram of a reverse voltage ringing elimination circuit according to one embodiment of the present invention.

[0012] The components include: current transformer L1, ringing elimination module 1, synchronous rectification module 2, frequency selection module 3, MOSFET Q1, capacitor C1, resistor R1, Zener diode D1, resistor R2, capacitor C2, and capacitor EC1. Detailed Implementation

[0013] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0014] In the description of embodiments of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of embodiments of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0015] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model according to the specific circumstances.

[0016] The following is combined with Figure 1 This describes a reverse voltage ringing elimination circuit according to an embodiment of the present invention.

[0017] A reverse voltage ringing elimination circuit includes a current transformer L1 and a ringing elimination module 1; the positive terminal of the ringing elimination module 1, the same-name terminal of the first winding and the opposite-name terminal of the second winding of the current transformer L1 are all electrically connected to the positive terminal of the output terminal of the synchronous rectification module 2, and the opposite-name terminal of the first winding of the current transformer L1 is used as the positive terminal of the output terminal of the elimination circuit. The same-name terminal of the second winding of the current transformer L1 is electrically connected to the control terminal of the ringing elimination module 1; The negative terminal of the ringing cancellation module 1 is electrically connected to the negative terminal of the output of the synchronous rectification module 2, and the negative terminal of the ringing cancellation module 1 is used as the negative terminal of the output of the cancellation circuit. When the MOSFET of synchronous rectification module 2 is turned off, the current transformer L1 drives the ringing elimination module 1 to turn off, and the ringing elimination module 1 absorbs the reverse voltage ringing. When the MOSFET of the synchronous rectification module 2 is turned on, the current transformer L1 drives the ringing elimination module 1 to turn on, and the ringing elimination module 1 provides power to the output terminal of the synchronous rectification module 2.

[0018] In a preferred embodiment of the reverse voltage ringing elimination circuit proposed in this utility model, such as... Figure 1 As shown, the first winding of the current transformer L1 automatically senses the DC pulse voltage output by the synchronous rectification module 2 (the DC pulse voltage changes as the MOSFET of the synchronous rectification module 2 is turned off or on). The second winding of the current transformer L1 will generate an induced voltage through mutual inductance with the first winding, thereby controlling the ringing elimination module 1 to turn off or on in accordance with the MOSFET of the synchronous rectification module 2. This achieves the purpose of absorbing reverse voltage ringing when the MOSFET of the synchronous rectification module 2 is turned off, thus eliminating reverse voltage ringing. When the MOSFET of the synchronous rectification module 2 is turned on, it provides power to the output terminal of the synchronous rectification module 2, thereby improving the efficiency of the application circuit (i.e., the circuit connected to the output terminal of the elimination circuit).

[0019] Furthermore, it also includes a frequency selection module 3; the same-name terminal of the second winding of the current transformer L1 is electrically connected to the control terminal of the ringing elimination module 1 via the frequency selection module 3.

[0020] In this embodiment, the second winding of the current transformer L1 is used to control the on or off of the ringing elimination module 1. Therefore, a frequency selection module 3 can be set between the same-name terminal of the second winding of the current transformer L1 and the control terminal of the ringing elimination module 1 to further filter the signal transmitted from the second winding of the current transformer L1, so as to adjust the response timing of the ringing elimination module 1 according to actual needs and expand more control methods for the ringing elimination module 1.

[0021] Furthermore, the ringing cancellation module 1 includes a MOSFET Q1 and a capacitor C1; the source of the MOSFET Q1 is used as the positive terminal of the ringing cancellation module 1, the gate of the MOSFET Q1 is used as the control terminal of the ringing cancellation module 1, one end of the capacitor C1 is used as the negative terminal of the ringing cancellation module 1; the drain of the MOSFET Q1 and the other end of the capacitor C1 are electrically connected. When MOSFET Q1 is turned off, ringing cancellation module 1 is turned off; When MOSFET Q1 is turned on, the ringing cancellation module 1 is turned on.

[0022] In this embodiment, the ringing elimination module 1 is preferably composed of a MOSFET Q1 and a capacitor C1. When the MOSFET Q1 is turned off, the reverse voltage ringing will charge the parasitic capacitance of the MOSFET Q1 and the capacitor C1, thereby eliminating (or absorbing) the reverse voltage ringing. When the MOSFET Q1 is turned on, the charged capacitor C1 can provide power to the output terminal of the synchronous rectification module 2 and play a clamping protection role for the output terminal of the synchronous rectification module 2.

[0023] Furthermore, the ringing cancellation module 1 also includes a resistor R1 and a Zener diode D1; the resistor R1 is connected in parallel between the source and gate of the MOSFET Q1, and the anode and cathode of the Zener diode D1 are electrically connected to the source and gate of the MOSFET Q1, respectively.

[0024] In this embodiment, in order to ensure the normal operation of MOSFET Q1, resistor R1 is used as the gate-source bias resistor of MOSFET Q1, and Zener diode D1 is used for overvoltage protection of MOSFET Q1.

[0025] Furthermore, the frequency selection module 3 includes a resistor R2 and a capacitor C2; the same-name terminal of the second winding of the current transformer L1 is connected in series with the capacitor C2 and the resistor R2, and then electrically connected to the control terminal of the ringing elimination module 1.

[0026] In this embodiment, the frequency selection module 3 is preferably composed of a resistor R2 and a capacitor C2. It has a simple structure. By adjusting the selection of resistor R2 and capacitor C2, a specific frequency band can be selected, and the timing of the subsequent ringing elimination module 1 can be controlled.

[0027] Furthermore, it also includes capacitor EC1; the positive terminal of capacitor EC1 is electrically connected to the opposite terminal of the first winding of transformer L1, and the negative terminal of capacitor EC1 is electrically connected to the negative terminal of ringing elimination module 1.

[0028] In this embodiment, in order to further reduce signal noise, it is preferable to connect a capacitor EC1 in parallel at the output of the cancellation circuit for filtering.

[0029] Other configurations and operations of the reverse voltage ringing elimination circuit according to the embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0030] In this specification, the terms "embodiment," "example," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0031] Although embodiments of the present invention have been shown and described, those skilled in the art will understand 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 claims and their equivalents.

Claims

1. A circuit for eliminating reverse voltage ringing, characterized in that: It includes a current transformer L1 and a ringing elimination module; the positive terminal of the ringing elimination module, the same-name terminal of the first winding and the opposite-name terminal of the second winding of the current transformer L1 are all electrically connected to the positive terminal of the output terminal of the synchronous rectification module, and the opposite-name terminal of the first winding of the current transformer L1 is used as the positive terminal of the output terminal of the elimination circuit. The same-name terminal of the second winding of the current transformer L1 is electrically connected to the control terminal of the ringing elimination module. The negative terminal of the ringing cancellation module is electrically connected to the negative terminal of the output terminal of the synchronous rectification module, and the negative terminal of the ringing cancellation module is used as the negative terminal of the output terminal of the cancellation circuit. When the MOSFET of the synchronous rectification module is turned off, the current transformer L1 drives the ringing elimination module to turn off, and the ringing elimination module absorbs reverse voltage ringing. When the MOS transistor of the synchronous rectification module is turned on, the current transformer L1 drives the ringing elimination module to turn on, and the ringing elimination module provides power to the output terminal of the synchronous rectification module.

2. The reverse voltage ringing elimination circuit according to claim 1, characterized in that: It also includes a frequency selection module; the same-name terminal of the second winding of the current transformer L1 is electrically connected to the control terminal of the ringing elimination module via the frequency selection module.

3. The reverse voltage ringing elimination circuit according to claim 1, characterized in that: The ringing cancellation module includes a MOSFET Q1 and a capacitor C1; the source of the MOSFET Q1 is used as the positive terminal of the ringing cancellation module, the gate of the MOSFET Q1 is used as the control terminal of the ringing cancellation module, one end of the capacitor C1 is used as the negative terminal of the ringing cancellation module, and the drain of the MOSFET Q1 and the other end of the capacitor C1 are electrically connected. When the MOS transistor Q1 is turned off, the ringing cancellation module is turned off; When the MOS transistor Q1 is turned on, the ringing cancellation module is turned on.

4. The reverse voltage ringing elimination circuit according to claim 3, characterized in that: The ringing cancellation module also includes a resistor R1 and a Zener diode D1; the resistor R1 is connected in parallel between the source and gate of the MOS transistor Q1, and the anode and cathode of the Zener diode D1 are electrically connected to the source and gate of the MOS transistor Q1, respectively.

5. The reverse voltage ringing elimination circuit according to claim 2, characterized in that: The frequency selection module includes a resistor R2 and a capacitor C2; the same-name terminal of the second winding of the current transformer L1 is connected in series with the capacitor C2 and the resistor R2, and then electrically connected to the control terminal of the ringing elimination module.

6. The reverse voltage ringing elimination circuit according to claim 1, characterized in that: It also includes a capacitor EC1; the positive terminal of the capacitor EC1 is electrically connected to the opposite terminal of the first winding of the current transformer L1, and the negative terminal of the capacitor EC1 is electrically connected to the negative terminal of the ringing elimination module.

Images