CN219304696U - Capacitor discharge control circuit and equipment - Google Patents

Abstract

The present application relates to a capacitor discharge control circuit and equipment. The circuit includes a switching power supply control circuit, a discharge circuit, a transistor and an auxiliary circuit, wherein the switching power supply control circuit is used to connect to the mains, one end of the discharge circuit is used to connect the switching power supply control circuit through an isolation transformer, and the other end of the discharge circuit is used for Discharge, the second pole of the transistor is connected to the other end of the discharge circuit, the third pole of the transistor is used for grounding, one end of the auxiliary circuit is used to connect the switching power supply control circuit through the isolation transformer, and the other end of the auxiliary circuit is connected to the first pole of the transistor; The auxiliary circuit is used to control the conduction of the transistor to discharge the discharge circuit when the control circuit of the switching power supply is in a non-working state; thus, the application enables the discharge circuit to discharge quickly by setting the transistor and the auxiliary circuit, and the circuit structure is simple and The cost is lower.

Description

Capacitor discharge control circuit and equipment

technical field

The present application relates to the technical field of capacitor discharge, in particular to a capacitor discharge control circuit and equipment.

Background technique

As the switching power supply is widely used in the lighting field and other fields, the switching power supply has many advantages such as high efficiency, long life, and small size; when the switching power supply is working, the large-capacity electrolytic capacitor at the output end will store a large amount of energy. The energy stored in these large electrolytic capacitors will not be released quickly, and the output terminal of the power supply will maintain a certain voltage for a long time.

However, in some switching power supply applications, this energy needs to be released quickly. Existing switching power supplies generally use resistive loads for discharge. If the resistance value is too small, it will affect the efficiency of the power supply. If the resistance value is too large, the discharge will be slow, which cannot meet the needs The problem of discharge effect; when other circuits are used to control the load discharge, there are problems of complicated circuit structure and high cost.

Utility model content

Based on this, it is necessary to address the above-mentioned technical problems and provide a capacitive discharge control circuit and device that can achieve the desired discharge effect, has a simple circuit structure, and is low in cost.

In a first aspect, the present application provides a capacitor discharge control circuit. The capacitor discharge control circuit includes:

Switching power supply control circuit, the switching power supply control circuit is used to connect to the mains;

Discharge circuit, one end of the discharge circuit is used to connect the switching power supply control circuit through the isolation transformer, and the other end of the discharge circuit is used for discharge;

A transistor, the second pole of the transistor is connected to the other end of the discharge circuit, and the third pole of the transistor is used for grounding;

Auxiliary circuit, one end of the auxiliary circuit is used to connect the switching power supply control circuit through the isolation transformer, and the other end of the auxiliary circuit is connected to the first pole of the transistor; the auxiliary circuit is used to control the conduction of the transistor when the switching power supply control circuit is in a non-working state to discharge the discharge circuit.

In one of the embodiments, the discharge circuit includes a first diode and a first energy storage unit;

The cathode of the first diode is connected to the secondary side winding of the isolation transformer, and the anode of the first diode is connected to one end of the first energy storage unit; one end of the first energy storage unit is used for discharging, and the other end of the first energy storage unit One end is connected to the secondary side winding of the isolation transformer, and the other end of the first energy storage unit is also used for grounding.

In one of the embodiments, the auxiliary circuit includes a second diode, a second energy storage unit and a resistance element;

The cathode of the second diode is connected to the secondary side winding of the isolation transformer, and the anode of the second diode is connected to one end of the second energy storage unit; one end of the second energy storage unit is connected to one end of the resistance element, and the second energy storage unit The other end of the second energy storage unit is also used for grounding; the other end of the resistance element is connected to the first pole of the transistor.

In one of the embodiments, the resistive element includes a first resistor and a second resistor;

One end of the first resistor is respectively connected to one end of the second energy storage unit and one end of the second resistor, the other end of the first resistor is connected to the other end of the second resistor, and the other end of the second resistor is connected to the first pole of the transistor.

In one of the embodiments, the first energy storage unit includes a first capacitor, and the second energy storage unit includes a second capacitor;

The capacitance of the first capacitor is greater than the capacitance of the second capacitor.

In one of the embodiments, the circuit further includes a third resistor;

One end of the third resistor is connected to the second pole of the transistor, and the other end of the third resistor is connected to the other end of the discharge circuit.

In one embodiment, one end of the switching power supply control loop is used to connect to the mains, and the other end of the switching power supply control loop is connected to the primary side winding of the isolation transformer.

In one of the embodiments, the circuit further includes a switching element;

One end of the switching element is used to connect to the mains, and the other end of the switching element is connected to the switching power supply control circuit.

In one embodiment, the transistor is a triode or a MOS transistor.

In a second aspect, the present application also provides a capacitor discharge control device. The device includes the above-mentioned capacitive discharge control circuit.

The above capacitor discharge control circuit and equipment, the circuit includes a switching power supply control circuit, a discharge circuit, a transistor and an auxiliary circuit, wherein the switching power supply control circuit is used to connect to the mains, and one end of the discharge circuit is used to connect to the switching power supply control circuit through an isolation transformer , the other end of the discharge circuit is used for discharging, the second pole of the transistor is connected to the other end of the discharge circuit, the third pole of the transistor is used for grounding, one end of the auxiliary circuit is used to connect the switching power supply control circuit through the isolation transformer, and the other end of the auxiliary circuit One end is connected to the first pole of the transistor; the auxiliary circuit is used to control the conduction of the transistor to discharge the discharge circuit when the switching power supply control circuit is in a non-working state; thus, the application makes the discharge circuit discharge by setting the transistor and the auxiliary circuit Capable of rapid discharge, simple circuit structure and low cost.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the traditional technology. Obviously, the accompanying drawings in the following description are only the present invention For some embodiments of the application, those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the structural block diagram of the capacitor discharge control circuit in an embodiment;

Fig. 2 is the circuit structural diagram of discharge circuit in an embodiment;

Fig. 3 is the circuit structure diagram of auxiliary circuit in an embodiment;

Fig. 4 is a circuit structure diagram of a capacitor discharge control circuit in an embodiment;

FIG. 5 is a circuit structure diagram of a capacitor discharge control circuit in another embodiment.

Detailed ways

In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the application are given in the drawings. However, the present application can be embodied in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of this application more thorough and comprehensive.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used herein in the specification of the application are only for the purpose of describing specific embodiments, and are not intended to limit the application.

It can be understood that the terms "first", "second" and the like used in this application may be used to describe various elements herein, but these elements are not limited by these terms. These terms are only used to distinguish one element from another element. For example, a first resistance could be termed a second resistance, and, similarly, a second resistance could be termed a first resistance, without departing from the scope of the present application. Both the first resistance and the second resistance are resistances, but they are not the same resistance.

It can be understood that "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if the connected circuits, modules, units, etc. have the transmission of electrical signals or data between each other.

When used herein, the singular forms "a", "an" and "the/the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising/comprising" or "having" etc. specify the presence of stated features, integers, steps, operations, components, parts or combinations thereof, but do not exclude the presence or addition of one or more The possibility of other features, integers, steps, operations, components, parts or combinations thereof.

At present, in some switching power supply applications, this energy needs to be released quickly. For example, switching power supplies used in LED (Light Emitting Diode, light-emitting diode) lighting need to quickly release the energy stored in the output large electrolytic capacitor when it is turned off, so as to quickly reduce the power consumption. The voltage of the LED lamp is used to prevent the flashback after the LED lamp is turned off. Improving this performance index is also necessary for the life of the LED and the user experience. However, there are a variety of existing measures to control and improve this performance index. When other circuits are used to control the discharge of large electrolytic capacitors, there are problems of complicated circuit structure and high cost.

This application relates to a capacitor discharge control circuit and equipment. The circuit structure is simple, and it can be realized only by adding an auxiliary winding and several electronic components on the secondary side of the transformer. It has the advantages of low cost, fast response speed, obvious effect, and reliable performance. .

In one embodiment, as shown in FIG. 1 , the present application provides a capacitor discharge control circuit, which includes:

Switching power supply control circuit 110, the switching power supply control circuit 110 is used to connect to the mains;

A discharge circuit 120, one end of the discharge circuit 120 is used to connect the switching power supply control circuit 110 through an isolation transformer, and the other end of the discharge circuit 120 is used for discharge;

A transistor 130, the second pole of the transistor 130 is connected to the other end of the discharge circuit 120, and the third pole of the transistor 130 is used for grounding;

Auxiliary circuit 140, one end of the auxiliary circuit 140 is used to connect the switching power supply control circuit 110 through the isolation transformer, and the other end of the auxiliary circuit 140 is connected to the first pole of the transistor 130; In the case of , the control transistor 130 is turned on to discharge the discharge loop.

Specifically, as shown in Figure 1, when the switching power supply control circuit 110 is in the working state, both the discharge circuit 120 and the auxiliary circuit 130 receive the output voltage of the switching power supply control circuit 110 through the isolation transformer, and at this time the auxiliary circuit 130 receives The voltage value received is slightly greater than the voltage value received by the discharge circuit 120, and the transistor 130 is in a non-conductive state at this time; when the switching power supply control circuit is in a non-working state, the voltage value output by the auxiliary circuit 130 drops, making the discharge circuit The voltage value output by 120 is greater than the voltage value output by the auxiliary circuit 130, and the transistor 130 is in an on state at this time, so that the discharge circuit 120 can be quickly discharged, and Vout+ in FIG. 1 is used for discharge.

In some examples, an isolation transformer can refer to a device that uses the principle of electromagnetic induction to change AC voltage, and its main functions include voltage conversion, current conversion, impedance conversion, isolation, voltage stabilization (magnetic saturation transformer), etc. The isolation transformer includes an iron core (or magnetic core) and a coil. The coil has two or more windings. The winding connected to the AC power supply is called the primary side winding, and the remaining windings are called the secondary side winding. When the primary side winding of the isolation transformer is connected to the AC power supply, an alternating magnetic flux is generated in the iron core, and the alternating magnetic flux induces an alternating current on the secondary side winding.

In one of the embodiments, as shown in FIG. 2, the discharge circuit may include a first diode (D1) and a first energy storage unit (C1);

The cathode of the first diode (D1) is connected to the secondary side winding of the isolation transformer, and the anode of the first diode (D1) is connected to one end of the first energy storage unit (C1); the first energy storage unit (C1) One end is used for discharging, the other end of the first energy storage unit (C1) is connected to the secondary side winding of the isolation transformer, and the other end of the first energy storage unit (C1) is also used for grounding.

Specifically, when the switching power supply control loop is in the working state, the first diode (D1) receives the voltage transmitted by the secondary side winding of the isolation transformer and rectifies it, and the rectified voltage can be used for the first storage The energy storage unit (C1) is charged; when the switching power supply control circuit is in a non-working state, after the transistor is turned on, the first energy storage unit can be quickly discharged, and Vout+ in Figure 1 is used for discharge.

Further, the first energy storage unit ( C1 ) may refer to an element capable of storing electric energy, for example, a battery or an inductor, and an inductor is used as an example for illustration in this embodiment of the present application.

In one of the embodiments, as shown in FIG. 3, the auxiliary circuit may include a second diode (D2), a second energy storage unit (C2) and a resistance element;

The negative pole of the second diode (D1) is connected to the secondary side winding of the isolation transformer, and the positive pole of the second diode (D1) is connected to one end of the second energy storage unit (C2); the second energy storage unit (C2) One end is connected to one end of the resistance element, the other end of the second energy storage unit (C2) is respectively connected to the secondary side winding of the isolation transformer and the other end of the resistance element, and the other end of the second energy storage unit (C2) is also used for grounding; The other end of the resistance element is connected to the first pole of the transistor.

Specifically, when the switching power supply control loop is in the working state, the second diode (D2) receives the voltage transmitted by the secondary side winding of the isolation transformer and rectifies it, and the rectified voltage can be used for the second storage The energy unit (C2) is charged; when the switching power supply control circuit is in a non-working state, the voltage output by the second energy storage unit (C2) is quickly discharged through the resistance element, so that the voltage value output by the second energy storage unit (C2) The voltage drops rapidly, and the voltage flows to the transistor through the resistance element. At this time, the output voltage value of the first energy storage unit (C1) is greater than the output voltage value of the second energy storage unit (C2), and the transistor is in the conduction state, so that the first energy storage unit (C1) The energy cell (C1) is discharged rapidly.

In one of the embodiments, as shown in FIG. 3, the resistance element may include a first resistor (R1) and a second resistor (R2);

One end of the first resistor (R1) is respectively connected to one end of the second energy storage unit (C2) and one end of the second resistor (R2), and the other end of the first resistor (R1) is connected to the other end of the second resistor (R2), The other end of the second resistor ( R2 ) is connected to the first pole of the transistor.

Specifically, as shown in Figure 3, when the switching power supply control circuit is in a non-working state, the voltage output by the second energy storage unit (C2) is quickly discharged through the first resistor (R1), so that the second energy storage unit The voltage value output by (C2) drops rapidly, and this voltage flows to the transistor through the second resistor (R2), at this time, the voltage value output by the first energy storage unit (C1) is greater than the voltage value output by the second energy storage unit (C2), The transistor is turned on to quickly discharge the first energy storage unit (C1).

In one of the embodiments, the first energy storage unit includes a first capacitor, and the second energy storage unit includes a second capacitor;

The capacitance of the first capacitor is greater than the capacitance of the second capacitor.

Specifically, the first energy storage unit (C1) shown in FIG. 2 is a first capacitor, the second energy storage unit (C2) shown in FIG. 3 is a second capacitor, and the capacitance of the first capacitor is greater than that of the first capacitor. The capacitance of the second capacitor; therefore, when the switching power supply control circuit is in a non-working state, the switching power supply control circuit stops charging the first capacitor and the second capacitor. Since the first capacitor is a large-capacity capacitor, the stored energy is relatively large And the impedance of the discharge circuit is relatively large, so it cannot be discharged quickly; the second capacitor is a small-capacity capacitor, and the stored energy is very small. Rapid discharge through the first resistor causes the output voltage of the second capacitor to drop rapidly, and this voltage is sent to the transistor through the second resistor. The first pole provides a voltage lower than that of the second pole of the transistor, and the transistor is turned on so as to quickly discharge the first capacitor.

In one of the embodiments, as shown in FIG. 4, the circuit may further include a third resistor (R3);

One end of the third resistor (R3) is connected to the second pole of the transistor (Q1), and the other end of the third resistor (R3) is connected to the other end of the discharge circuit.

Specifically, as shown in FIG. 4, the second capacitor is rapidly discharged through the first resistor so that the voltage at V1+ drops rapidly, and this voltage provides a voltage lower than the second electrode of the transistor to the first electrode of the transistor through the second resistor, and the transistor is turned on. The first capacitor is quickly discharged through the third resistor (R3).

In one embodiment, one end of the switching power supply control loop is used to connect to the mains, and the other end of the switching power supply control loop is connected to the primary side winding of the isolation transformer.

Specifically, the switching power supply control circuit outputs voltage to the secondary side winding of the isolation transformer through the primary side winding of the isolation transformer.

In one of the embodiments, as shown in Figure 5, the circuit further includes a switching element (K1);

One end of the switch element (K1) is used to connect to the mains, and the other end of the switch element (K1) is connected to the switching power supply control circuit.

Specifically, as shown in Figure 5, when the switching element (K1) is in the closed state, the switching power supply control loop is in the working state; when the switching element (K1) is in the non-closed state, the switching power supply control loop is in the non- working status.

In one embodiment, the transistor is a triode or a MOS transistor.

Specifically, this application uses a triode as an example for illustration, wherein the first pole of the transistor may refer to the base of the triode, the second pole of the transistor may refer to the emitter of the triode, and the third pole of the transistor may refer to the collector of the triode .

In an embodiment, the present application also provides a capacitor discharge control device. The device includes the above-mentioned capacitive discharge control circuit.

Specifically, as shown in Figure 5, the capacitor discharge control device includes the above-mentioned capacitor discharge control circuit. When the switching element is in the closed state, the switching power supply control circuit enters the working state, and drives the primary side winding of the isolation transformer to enter the working state. At the same time, the secondary side winding of the isolation transformer also starts to output voltage, and after being rectified by the first diode, the output voltage (Vout+) will be charged to the first capacitor (large capacitance), and the output voltage (Vout+) will be charged to the second capacitor after being rectified by the second diode. Capacitor (small capacitance) charging output voltage (V1+); rationally design the secondary side winding of the isolation transformer so that the rectified V1+ voltage is slightly greater than the Vout+ voltage, so that when the switching power supply control circuit enters the working state, the V1+ voltage passes through the second The resistor provides a voltage greater than the emitter of the triode to the base of the triode (the triode can also be selected as a P-type MOS tube), so that the triode is cut off, and the third resistor is not turned on.

When the switching element is in the non-closed state, the switching power supply control circuit is in the non-working state, driving the primary side winding of the isolation transformer to enter the non-working state, and at the same time, the secondary side winding of the isolation transformer also stops the first capacitor and the second capacitor. Charging, because the first capacitor is a large-capacity capacitor, the stored energy is relatively large and the impedance of the discharge circuit is relatively large, so it cannot be discharged quickly; the second capacitor is a small-capacity capacitor, the stored energy is very small, and the rapid discharge through the first resistor makes it The voltage of V1+ drops rapidly, and this voltage provides a voltage lower than the emitter of the triode to the base of the triode (the triode can also be a P-type MOS tube) through the second resistor to make the triode conduct, and the third resistor conducts to quickly discharge the first capacitor ;

By reasonably selecting the resistance values of the first resistor, the second resistor and the third resistor and the parameters of the transistor, the effect of quickly discharging the large-capacity output capacitor of the switching power supply can be achieved.

In the description of this specification, descriptions referring to the terms "some embodiments", "other embodiments", "ideal embodiments" and the like mean that specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in this specification. In at least one embodiment or example of the utility model. In this specification, schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

The technical features of the above embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be It is considered to be within the range described in this specification.

The above-mentioned embodiments only express several implementation modes of the present application, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be determined by the appended claims.

Claims (10)

1. A capacitor discharge control circuit, characterized in that the circuit comprises: A switching power supply control circuit, the switching power supply control circuit is used to connect to the mains; A discharge circuit, one end of the discharge circuit is used to connect the switching power supply control circuit through an isolation transformer, and the other end of the discharge circuit is used for discharge; a transistor, the second pole of the transistor is connected to the other end of the discharge circuit, and the third pole of the transistor is used for grounding; An auxiliary circuit, one end of the auxiliary circuit is used to connect the switching power supply control circuit through the isolation transformer, and the other end of the auxiliary circuit is connected to the first pole of the transistor; When the power supply control loop is in a non-working state, the transistor is controlled to be turned on so as to discharge the discharge loop. 2. The capacitor discharge control circuit according to claim 1, wherein the discharge circuit comprises a first diode and a first energy storage unit; The cathode of the first diode is connected to the secondary side winding of the isolation transformer, and the anode of the first diode is connected to one end of the first energy storage unit; one end of the first energy storage unit is used for For discharging, the other end of the first energy storage unit is connected to the secondary side winding of the isolation transformer, and the other end of the first energy storage unit is also used for grounding. 3. The capacitor discharge control circuit according to claim 2, wherein the auxiliary circuit comprises a second diode, a second energy storage unit and a resistance element; The cathode of the second diode is connected to the secondary side winding of the isolation transformer, and the anode of the second diode is connected to one end of the second energy storage unit; one end of the second energy storage unit is connected to One end of the resistance element and the other end of the second energy storage unit are respectively connected to the secondary side winding of the isolation transformer and the other end of the resistance element, and the other end of the second energy storage unit is also used for grounding; the other end of the resistance element is connected to the first pole of the transistor. 4. The capacitor discharge control circuit according to claim 3, wherein the resistive element comprises a first resistor and a second resistor; One end of the first resistor is respectively connected to one end of the second energy storage unit and one end of the second resistor, the other end of the first resistor is connected to the other end of the second resistor, and the second resistor The other end is connected to the first pole of the transistor. 5. The capacitive discharge control circuit according to claim 3, wherein the first energy storage unit comprises a first capacitor, and the second energy storage unit comprises a second capacitor; The capacitance of the first capacitor is greater than the capacitance of the second capacitor. 6. The capacitor discharge control circuit according to any one of claims 1 to 5, wherein the circuit further comprises a third resistor; One end of the third resistor is connected to the second pole of the transistor, and the other end of the third resistor is connected to the other end of the discharge circuit. 7. The capacitor discharge control circuit according to any one of claims 1 to 5, wherein one end of the switching power supply control loop is used to connect to the mains, and the other end of the switching power supply control loop is connected to the isolated The primary winding of the transformer. 8. The capacitor discharge control circuit according to any one of claims 1 to 5, wherein the circuit further comprises a switching element; One end of the switching element is used to connect to the mains, and the other end of the switching element is connected to the switching power supply control circuit. 9. The capacitor discharge control circuit according to claim 1, wherein the transistor is a triode or a MOS transistor. 10. A capacitive discharge control device, comprising the capacitive discharge control circuit according to any one of claims 1-9.

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