Switching power supply preceding-stage high-low voltage composite indicating circuit

Abstract

The utility model belongs to the field of power equipment, and relates to a switching power supply preceding-stage high-low voltage composite indicating circuit, which comprises a protection circuit, a constant-value voltage driving circuit, an overvoltage driving circuit and a rectification filter circuit, and is characterized in that the constant-value voltage driving circuit is electrically connected with the protection circuit, the overvoltage driving circuit and the rectification filter circuit; the constant-value voltage driving circuit and the overvoltage driving circuit are electrically connected with the LED indicating lamp; the constant-value voltage driving circuit is composed of a third diode D3, a first voltage-regulator tube ZD1, a first resistor R1, a second resistor R2 and a first capacitor C1, and the ZD1 is switched on to drive an indicating lamp LED1 to be turned on; the overvoltage driving circuit is composed of a comparator U1, a sixth diode D6, a second voltage-regulator tube ZD2, a TVS tube D7, resistors R3-R8 and capacitors C2-C3, and can drive an indicating lamp LED1 to flicker in an overvoltage state. According to the utility model, a single indicating lamp and a small number of components are adopted, and power supply preceding-stage high-low voltage composite multi-state indication is realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of electric power equipment, and more specifically, is a high-low voltage composite indicating circuit for the front stage of a switching power supply, which can indicate the state of AC power supply from low voltage to overvoltage with only a single indicating lamp. Background Art

[0002] With the advent of the post-PC era, voltage acquisition and monitoring technology has penetrated into various industries and people's daily lives. The widespread application of voltage acquisition and monitoring technology has realized real-time monitoring of power supply systems.

[0003] At present, most of the voltage collection and monitoring of power devices use PT voltage transformers plus AD digital-to-analog conversion chips, combined with single-chip microcomputers to realize real-time monitoring and indication of power supply voltage. If the voltage indication part is on the high-voltage AC side, isolation and safety issues need to be considered. For this reason, it is also necessary to add isolation devices such as photocouplers to realize the low-voltage part driving the high-voltage part indication circuit. In this case, not only will the circuit be more complicated and the cost will be higher, but the AD digital-to-analog conversion chip and single-chip microcomputer may have problems such as program deviation, interference and crash, and the reliability is not high. Utility Model Content

[0004] The utility model designs a high-low voltage composite indication circuit for the front stage of a switching power supply, which can indicate the state of the power supply from low voltage to overvoltage with only a single indicator light. The technical solution adopted by the utility model is as follows:

[0005] A switching power supply front-stage high-low voltage composite indication circuit, comprising a protection circuit, a fixed-value voltage drive circuit, an overvoltage drive circuit and a rectifier filter circuit, wherein the fixed-value voltage drive circuit is electrically connected to the protection circuit, the overvoltage drive circuit and the rectifier filter circuit respectively, and the fixed-value voltage drive circuit and the overvoltage drive circuit are electrically connected to LED indicator lights respectively;

[0006] The fixed voltage driving circuit includes a third diode D3, the positive electrode of D3 is connected to the protection circuit, the negative electrode of D3 is connected to the negative electrode of the first voltage regulator ZD1, the positive electrode of ZD1 is connected to one end of the first resistor R1, the other end of R1 is connected to one end of the second resistor R2, the other end of R2 is connected to the positive electrode of the LED lamp, one end of the first capacitor C1 is grounded, the other end of C1 is connected between R1 and R2, and the negative electrode of the LED lamp is grounded;

[0007] The overvoltage driving circuit includes a sixth diode D6, the positive electrode of D6 is connected between R1 and R2, the negative electrode of D6 is connected to the negative electrode of the second voltage regulator tube ZD2, the positive electrode of ZD2 is connected to one end of the third resistor R3, the other end of R3 is connected to the output end of the comparator U1, one end of the sixth resistor R6 is connected to the output end of U1, the other end of R6 is connected to the positive electrode of the LED lamp, the positive input end of the power supply of U1 is connected to the positive electrode of ZD2, the negative input end of the power supply of U1 is grounded, the same-direction input end of U1 is connected to one end of the fifth resistor R5, R5 The other end is connected to the other end of R3, the reverse input end of U1 is connected to one end of the eighth resistor R8 and one end of the third capacitor C3, the other end of R8 is connected to the output end of U1, and the other end of C3 is grounded, one end of the fourth resistor R4 is connected to the positive electrode of ZD2, and the other end of R4 is connected to the same-direction input end of U1, one end of the seventh resistor R7 is connected to the same-direction input end of U1, and the other end of R7 is grounded, one end of the second capacitor C2 is connected to the positive electrode of ZD2, and the other end of C2 is grounded, one end of the TVS tube D7 is connected to the positive electrode of ZD2, and the other end of D7 is grounded.

[0008] Preferably, the protection circuit includes a varistor RVS1 and a power inductor LR1, the AC live wire ACL of the AC input port J1 is respectively connected to one end of RVS1 and LR1, the AC neutral wire ACN of J1 is respectively connected to GND and the other end of RVS1, the other end of RVS1 is grounded, and the other end of LR1 is connected to the positive electrode of D3 in the fixed voltage drive circuit.

[0009] Preferably, the rectifier and filter circuit includes a first diode D1, an anode of D1 is connected to an anode of a third diode D3 in the fixed voltage drive circuit, a cathode of D1 is connected to an anode of a second diode D2, a cathode of D2 is connected to one end of an X-capacitor CX1, the other end of CX1 is connected to an anode of a fifth diode D5, a cathode of D5 is connected to an anode of a fourth diode D4, a cathode of D4 is grounded, a cathode of a switching power supply is connected to a cathode of D2, a cathode of the switching power supply is connected to a cathode of D5, and the X-capacitor CX1 is connected between the positive and negative electrodes of the switching power supply.

[0010] Beneficial effects of the utility model:

[0011] Compared with the existing voltage acquisition indication circuit, the utility model is applied to the high-voltage side of the front stage of the switching power supply, adopts a single indicator light and a small number of components, does not involve the software part, and can realize the high and low voltage composite multi-state indication of the front stage of the power supply, with low cost and high reliability. It can also be used for three-phase voltage state indication, and the circuit has good scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0013] Figure 1It is the electrical connection diagram of the high and low voltage composite indication circuit in the front stage of the switching power supply;

[0014] Figure 2 It is a schematic diagram of the structure and principle of the high and low voltage composite indication circuit in the front stage of the switching power supply. DETAILED DESCRIPTION

[0015] The technical solution of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present utility model, rather than all of the embodiments.

[0016] like Figure 1 , 2 As shown, a high-low voltage composite indication circuit of the front stage of a switching power supply, the fixed voltage drive circuit is electrically connected to the protection circuit, the overvoltage drive circuit and the rectifier filter circuit respectively, the fixed voltage drive circuit and the overvoltage drive circuit are electrically connected to the LED indicator light respectively, the AC power input is connected to the protection circuit, and the rectifier filter circuit is connected to the switching power supply.

[0017] Protection circuit: including varistor RVS1 and power inductor LR1. The AC live wire ACL of the AC input port J1 is connected to RVS1 and one end of LR1 respectively. The AC neutral wire ACN of J1 is connected to GND and the other end of RVS1 respectively. The other end of RVS1 is grounded, and the other end of LR1 is connected to the fixed voltage drive circuit. The varistor RVS1 can discharge a large current in time when a lightning surge interference occurs at the AC input port J1, and clamp the voltage at a lower level. The power inductor LR1 is used for decoupling to ensure that the front-stage varistor acts first when there is a lightning surge interference.

[0018] Fixed voltage driving circuit: the positive electrode of the third diode D3 is connected to the other end of LR1 of the protection circuit, the negative electrode of D3 is connected to the negative electrode of the first voltage regulator ZD1, the positive electrode of ZD1 is connected to one end of the first resistor R1, the other end of R1 is connected to one end of the second resistor R2, the other end of R2 is connected to the positive electrode of the LED lamp, one end of the first capacitor C1 is grounded, and the other end is connected between R1 and R2, the negative electrode of the LED lamp is grounded, and the overvoltage driving circuit is connected between R1 and R2.

[0019] The fixed voltage driving circuit is composed of a third diode D3, a first voltage regulator ZD1, a first resistor R1, a second resistor R2 and a first capacitor C1. The voltage regulation value of the first voltage regulator ZD1 should be 80% of the peak voltage of the AC rated voltage, so that when the AC input voltage is higher than 80% of the rated voltage, the first voltage regulator ZD1 is turned on. The third diode D3 rectifies the AC sinusoidal voltage into a DC pulsating voltage. When the peak value of the DC pulsating voltage (equal to the AC rated peak voltage before rectification) is higher than the voltage regulation value of the first voltage regulator ZD1, the first voltage regulator ZD1 is turned on, and after current limiting by R1 and R2 and filtering by C1, the indicator LED1 is driven to light up. The brightness of the indicator LED1 is positively correlated with the AC power supply voltage.

[0020] Overvoltage drive circuit: The anode of the sixth diode D6 is connected between R1 and R2, the cathode of D6 is connected to the cathode of the second voltage regulator ZD2, the anode of ZD2 is connected to one end of the third resistor R3, the other end of R3 is connected to the output end of the comparator U1, one end of the sixth resistor R6 is connected to the output end of U1, the other end of R6 is connected to the anode of the LED lamp (also connected to the other end of R2), the positive input end of the power supply of U1 is connected to the positive electrode of ZD2, the negative input end of the power supply of U1 is grounded, and the same-direction input end of U1 is connected to one end of the fifth resistor R5 , the other end of R5 is connected to the other end of R3, the reverse input end of U1 is connected to one end of the eighth resistor R8 and one end of the third capacitor C3, the other end of R8 is connected to the output end of U1, and the other end of C3 is grounded, one end of the fourth resistor R4 is connected to the positive electrode of ZD2, and the other end of R4 is connected to the same-direction input end of U1, one end of the seventh resistor R7 is connected to the same-direction input end of U1, and the other end of R7 is grounded, one end of the second capacitor C2 is connected to the positive electrode of ZD2, and the other end of C2 is grounded, one end of the TVS tube D7 is connected to the positive electrode of ZD2, and the other end of D7 is grounded.

[0021] The overvoltage drive circuit is composed of a comparator U1, a sixth diode D6, a second voltage regulator ZD2, a TVS tube D7, resistors R3~R8, and capacitors C2~C3. The sixth diode D6 ensures that the current flows into the overvoltage drive circuit in one direction. When the AC input voltage is higher than 120% of the rated voltage, the second voltage regulator ZD2 is turned on and the current flows into the overvoltage drive circuit. The TVS tube D7 prevents damage to the comparator U1 when an overvoltage occurs. The second capacitor C2 is used for energy storage and filtering when the comparator U1 is powered. The comparator U1, resistors R3~R8, and the third capacitor C3 form a PWM wave generation circuit, which can drive the indicator LED1 to flash in an overvoltage state.

[0022] Rectification and filtering circuit: The positive electrode of the first diode D1 is connected to the positive electrode of the third diode D3 in the fixed voltage driving circuit, the negative electrode of D1 is connected to the positive electrode of the second diode D2, the negative electrode of D2 is connected to one end of the X capacitor CX1, the other end of CX1 is connected to the positive electrode of the fifth diode D5, the negative electrode of D5 is connected to the positive electrode of the fourth diode D4, and the negative electrode of D4 is grounded. The positive electrode of the switching power supply is connected to the negative electrode of D2, the negative electrode of the switching power supply is connected to the positive electrode of D5, and the X capacitor CX1 is connected between the positive and negative electrodes of the switching power supply.

[0023] The rectifier and filter circuit is composed of diodes D1, D2, D4, D5 and safety X capacitor CX1. Diodes D1, D2, D4, D5 are used for rectification, and X capacitor CX1 is used for filtering.

[0024] The meaning of GND in the figure stands for the neutral line. GND means the common terminal, or the ground, but this ground is not the real earth. It is a ground assumed for application and provides a potential reference for other nodes.

[0025] When the AC power supply voltage J1 connected is lower than 80% of the rated voltage, the indicator light goes out; when the power supply voltage is higher than 80% of the rated voltage and lower than 120% of the rated voltage, ZD1 is turned on, ZD2 is turned off, the overvoltage drive circuit does not work, the output end of U1 is in a high-resistance state, the current only flows through R2 and LED, the indicator light is on, and the degree of brightness reflects the current voltage level; when the power supply voltage is higher than 120% of the rated voltage, ZD1 and ZD2 are both turned on, the overvoltage drive circuit starts to work, and the output end of U1 cyclically outputs high and low level PWM waves. When the output is low level, the LED light is in the off state, the current only flows through R2 and R6, not through the LED, and the LED is not bright; when the output is high level, the LED light is in the on state, the current flows through R2, R6 and merges into the LED, and the LED is bright. So when the power supply voltage is higher than 120% of the rated voltage, the LED flashes cyclically. The indicator light flashes. This circuit can be used in the front stage of the switching power supply to indicate the current power supply voltage state.

[0026] In the prior art, there are known circuit structures that can be substituted to achieve the same function: protection circuit, rectification and filtering circuit.

[0027] Under the requirements of low AC power supply voltage acquisition accuracy, high stability, low cost, and single LED lamp multi-function indication, the utility model abandons the solution of AD acquisition plus single-chip microcomputer plus isolation drive, and directly deploys a high-low voltage composite indication circuit at the front stage of the switching power supply, that is, the high-voltage primary side. Through the combination of a fixed-value voltage drive circuit and an overvoltage drive circuit (the overvoltage drive circuit can only be started under the premise that the fixed-value voltage drive circuit is started), the high-low voltage composite multi-state indication function requirement of the front stage of the power supply is realized.

[0028] In the embodiments of the utility model, the technical features not described in detail are all existing technologies or conventional technical means and will not be described in detail here.

[0029] Finally, it should be noted that the above embodiments are only specific implementation methods of the present utility model, which are used to illustrate the technical solution of the present utility model, rather than to limit it, and the protection scope of the present utility model is not limited thereto. Those skilled in the art should understand that any technician familiar with the technical field can modify the technical solution recorded in the above embodiments within the technical scope disclosed by the present utility model, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solution of the embodiment of the present utility model, and should be covered within the protection scope of the present utility model.

Claims

1. A high-low voltage composite indication circuit for the front stage of a switching power supply, characterized in that: It includes a protection circuit, a fixed-value voltage driving circuit, an overvoltage driving circuit and a rectifier and filter circuit, wherein the fixed-value voltage driving circuit is electrically connected to the protection circuit, the overvoltage driving circuit and the rectifier and filter circuit respectively, and the fixed-value voltage driving circuit and the overvoltage driving circuit are electrically connected to the LED indicator light respectively; The fixed voltage driving circuit includes a third diode D3, the positive electrode of D3 is connected to the protection circuit, the negative electrode of D3 is connected to the negative electrode of the first voltage regulator ZD1, the positive electrode of ZD1 is connected to one end of the first resistor R1, the other end of R1 is connected to one end of the second resistor R2, the other end of R2 is connected to the positive electrode of the LED lamp, one end of the first capacitor C1 is grounded, the other end of C1 is connected between R1 and R2, and the negative electrode of the LED lamp is grounded; The overvoltage driving circuit includes a sixth diode D6, the positive electrode of D6 is connected between R1 and R2, the negative electrode of D6 is connected to the negative electrode of the second voltage regulator tube ZD2, the positive electrode of ZD2 is connected to one end of the third resistor R3, the other end of R3 is connected to the output end of the comparator U1, one end of the sixth resistor R6 is connected to the output end of U1, the other end of R6 is connected to the positive electrode of the LED lamp, the positive input end of the power supply of U1 is connected to the positive electrode of ZD2, the negative input end of the power supply of U1 is grounded, the same-direction input end of U1 is connected to one end of the fifth resistor R5, R5 The other end is connected to the other end of R3, the reverse input end of U1 is connected to one end of the eighth resistor R8 and one end of the third capacitor C3, the other end of R8 is connected to the output end of U1, and the other end of C3 is grounded, one end of the fourth resistor R4 is connected to the positive electrode of ZD2, and the other end of R4 is connected to the same-direction input end of U1, one end of the seventh resistor R7 is connected to the same-direction input end of U1, and the other end of R7 is grounded, one end of the second capacitor C2 is connected to the positive electrode of ZD2, and the other end of C2 is grounded, one end of the TVS tube D7 is connected to the positive electrode of ZD2, and the other end of D7 is grounded.

2. A switching power supply front-stage high-low voltage composite indication circuit according to claim 1, characterized in that: The protection circuit includes a varistor RVS1 and a power inductor LR1. The AC live wire ACL of the AC input port J1 is connected to one end of RVS1 and LR1 respectively, the AC neutral wire ACN of J1 is connected to GND and the other end of RVS1 respectively, the other end of RVS1 is grounded, and the other end of LR1 is connected to the positive electrode of D3 in the fixed voltage drive circuit.

3. A switching power supply front-stage high-low voltage composite indication circuit according to claim 1, characterized in that: The rectifier and filter circuit comprises a first diode D1, an anode of D1 is connected to an anode of a third diode D3 in a fixed voltage driving circuit, a cathode of D1 is connected to an anode of a second diode D2, a cathode of D2 is connected to one end of an X capacitor CX1, the other end of CX1 is connected to an anode of a fifth diode D5, a cathode of D5 is connected to an anode of a fourth diode D4, a cathode of D4 is grounded, a cathode of a switching power supply is connected to a cathode of D2, a cathode of the switching power supply is connected to a cathode of D5, and the X capacitor CX1 is connected between the positive and negative electrodes of the switching power supply.

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