LED driving power supply

Abstract

The present invention discloses an LED driving power supply, comprising: an operational amplifier, a voltage regulating circuit, a voltage dividing circuit, a voltage stabilizing circuit, a PWM controller, and a DC power supply; the DC power supply is connected to the in-phase input terminal of the operational amplifier through the voltage regulating circuit; the voltage dividing circuit of the DC power supply is connected to the reverse input terminal of the operational amplifier; the output terminal of the operational amplifier is connected to the PWM controller through the voltage stabilizing circuit. The present invention adjusts the magnitude of the voltage at the input terminal of the operational amplifier by setting a voltage regulating circuit, so that the output current of the LED driving power supply changes with the magnitude of the voltage at the input terminal of the operational amplifier, and controls the temperature of the LED driving power supply and the lamp beads within a fixed range, thereby effectively protecting the components and lamp beads in the LED driving power supply, so that the two will not fail due to the deterioration of temperature, thereby ensuring the stability and safety of the subway lighting system.

Description

Technical Field

[0001] The invention belongs to the technical field of LED driving, and in particular relates to an LED driving power supply. Background Art

[0002] In the field of subway lighting systems, almost all of them now use LEDs. The LED driver usually uses a switching power supply. Most of them work in a constant current mode. The power supply is often installed together with the lamp beads. The heat of the lamp beads and the heat of the power supply itself work together, which will cause the temperature of the power supply and the lamp beads to rise. Therefore, this constant current working mode has the following disadvantages: 1. When the ambient temperature is relatively bad, especially when it is high, the LED driver power supply will continue to heat up; 2. The voltage of the LED chip itself will also rise with the temperature rise, so the load of the power supply is further increased; 3. The temperature rise of the power supply and the lamp beads will cause a vicious cycle. The lamp beads and the power supply are prone to failure due to excessive temperature; 4. The LED power supply with protection function automatically cuts off the power, causing the lamp to fail to work continuously. Based on this, some power supplies take over-temperature protection, that is, when the temperature reaches a certain value, the power supply automatically cuts off the power. This solution does not fundamentally solve the problem and will also make the lighting system unable to work normally. Summary of the invention

[0003] In order to overcome the above technical defects, the present invention provides an LED driving power supply, which controls the temperature of the LED driving power supply and lamp beads within a fixed range, thereby ensuring the stability and safety of the subway lighting system.

[0004] In order to solve the above problems, the present invention is implemented according to the following technical solutions:

[0005] An LED driving power supply includes: an operational amplifier, a voltage regulating circuit, a voltage dividing circuit, a voltage stabilizing circuit, a PWM controller, and a DC power supply;

[0006] The DC power supply is connected to the in-phase input terminal of the operational amplifier through the voltage regulating circuit; the voltage divider circuit of the DC power supply is connected to the inverting input terminal of the operational amplifier; and the output terminal of the operational amplifier is connected to the PWM controller through the voltage stabilizing circuit.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: by setting a voltage regulating circuit to adjust the voltage at the input end of the operational amplifier, the voltage output by the operational amplifier changes, and the output current of the PWM changes with the change of the voltage, so that the temperature of the LED driving power supply and the lamp beads are controlled within a fixed range, thereby effectively protecting the components and lamp beads in the LED driving power supply, so that the two will not fail due to temperature deterioration, thereby ensuring the stability and safety of the subway lighting system.

[0008] As a further improvement of the present invention, the voltage regulating circuit includes: a first resistor, a second resistor and a third resistor, and the LED driving power supply also includes a fourth resistor;

[0009] The DC power supply is connected to the non-inverting input terminal of the operational amplifier through the first resistor, the second resistor and the fourth resistor in sequence; the DC power supply is grounded through the first resistor, the second resistor and the third resistor in sequence.

[0010] As a further improvement of the present invention, the second resistor is an adjustable resistor.

[0011] As a further improvement of the present invention, the third resistor is a thermistor.

[0012] As a further improvement of the present invention, the third resistor is a negative temperature coefficient thermistor.

[0013] As a further improvement of the present invention, the voltage divider circuit includes: a fifth resistor and a sixth resistor, and the LED driving power supply also includes a seventh resistor;

[0014] The DC power supply is connected to the inverting input terminal of the operational amplifier through the fifth resistor and the seventh resistor in sequence; the DC power supply is grounded through the fifth resistor and the sixth resistor in sequence.

[0015] As a further improvement of the present invention, the voltage stabilizing circuit includes: an eighth resistor and a voltage stabilizing diode; the output end of the operational amplifier is connected to the PWM controller through the eighth resistor, and the operational amplifier is grounded through the eighth resistor.

[0016] As a further improvement of the present invention, the LED driving power supply further includes a ninth resistor, and the in-phase input terminal of the operational amplifier is connected to the output terminal of the operational amplifier through the ninth resistor.

[0017] As a further improvement of the present invention, the LED driving power supply further includes a tenth resistor, and the inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier through the tenth resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 It is a circuit diagram of the LED driving power supply described in the embodiment. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0021] Example

[0022] The present invention discloses an LED driving power supply, which is characterized in that it comprises: an operational amplifier U1, a voltage regulating circuit, a voltage dividing circuit, a voltage stabilizing circuit, a PWM controller, and a direct current power supply VCC; the direct current power supply VCC is connected to the in-phase input terminal of the operational amplifier U1 through the voltage regulating circuit; the direct current power supply voltage dividing circuit is connected to the reverse input terminal of the operational amplifier U1; the output terminal of the operational amplifier U1 is connected to the PWM controller through the voltage stabilizing circuit, the power supply pin of the operational amplifier U1 is connected to the direct current power supply VCC, and the ground pin of the operational amplifier U1 is grounded.

[0023] In the above embodiment, the voltage regulating circuit includes: a first resistor R1, a second resistor R2 and a third resistor R3, and the LED driving power supply also includes a fourth resistor R4; the DC power supply is connected to the in-phase input terminal of the operational amplifier U1 through the first resistor R1, the second resistor R2 and the fourth resistor R4 in sequence; the DC power supply VCC is grounded through the first resistor R1, the second resistor R2 and the third resistor R3 in sequence, wherein the first resistor R1 is a common resistor, the second resistor R2 is an adjustable resistor, and the third resistor R3 is a thermistor.

[0024] Preferably, the third resistor R3 is a negative temperature coefficient thermistor.

[0025] In the above embodiment, the voltage divider circuit includes: a fifth resistor R5 and a sixth resistor R6, and the LED driving power supply also includes a seventh resistor R7; the DC power supply is connected to the reverse input terminal of the operational amplifier U1 through the fifth resistor R5 and the seventh resistor R7 in sequence; the DC power supply VCC is grounded through the fifth resistor R5 and the sixth resistor R6 in sequence.

[0026] In the above embodiment, the voltage stabilizing circuit includes: an eighth resistor R8 and a voltage stabilizing diode D1; the output end of the operational amplifier U1 is connected to the PWM controller through the eighth resistor R8, and the operational amplifier U1 is grounded through the eighth resistor R8.

[0027] In the above embodiment, a ninth resistor R9 is further included, and the non-inverting input terminal of the operational amplifier U1 is connected to the output terminal of the operational amplifier U1 through the ninth resistor R9.

[0028] In the above embodiment, a tenth resistor R10 is further included, and the inverting input terminal of the operational amplifier U1 is connected to the output terminal of the operational amplifier U1 through the tenth resistor R10.

[0029] Next, this embodiment is further explained in conjunction with the specific implementation process, as follows:

[0030] The fifth resistor R5 and the sixth resistor R6 form a voltage divider circuit, which serves as a reference voltage for the current control signal. The first resistor R1, the second resistor R2 and the third resistor R3 form a voltage regulating circuit. The first resistor R1 is a common resistor, the second resistor R2 is an adjustable resistor, and the third resistor R3 is a thermistor with a negative temperature coefficient. When the temperature changes, the resistance of the third resistor R3 changes, and the voltage at the connection point between the second resistor R2 and the third resistor R3 also changes accordingly. The voltage thereat is connected to the in-phase input terminal of the operational amplifier U1 through the fourth resistor. The first resistor R1-seventh resistor R7, ninth resistor R9 and tenth resistor R10 form a subtractor. When the temperature of the third resistor R3 is low, the voltage at the upper end of the third resistor R3 is much higher than the reference voltage at the upper end of the sixth resistor R6. At this time, the operational amplifier U1 outputs a maximum voltage value. Through the eighth resistor R8 and the voltage stabilizing diode D1, the voltage is stabilized at a fixed value. In this embodiment, the value is 2.4V, and the voltage is connected to the current control terminal of the PWM controller. When the temperature of the third resistor R3 rises to 70°C, the resistance of the third resistor R3 decreases and the voltage drops. At this time, the voltage output by the operational amplifier U1 also drops. When the temperature of the third resistor R3 rises to 80°C, the resistance of the third resistor R3 further decreases and the voltage continues to drop. At this time, the output voltage of the operational amplifier U1 also drops to below 2.4V, and the current output of the PWM controller also decreases accordingly, thereby controlling the current at the output end of the operational amplifier U1, controlling the temperature of the LED driver power supply and the lamp beads within a certain range, and effectively protecting the components and lamp beads in the LED driver power supply from failure due to temperature deterioration, thereby ensuring the stability and safety of the subway lighting system.

[0031] The voltage input to the PWM changes, causing the current output by the PWM to change. For details about this part, please refer to the prior art and will not be described in detail here.

[0032] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Therefore, any modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An LED driving power supply, characterized in that: include: Operational amplifier, voltage regulating circuit, voltage dividing circuit, voltage stabilizing circuit, PWM controller, DC power supply; The DC power supply is connected to the in-phase input terminal of the operational amplifier through the voltage regulating circuit; the DC power supply is connected to the inverting input terminal of the operational amplifier through the voltage dividing circuit; the output terminal of the operational amplifier is connected to the PWM controller through the voltage stabilizing circuit; The voltage regulating circuit includes: a first resistor, a second resistor and a third resistor, and the LED driving power supply also includes a fourth resistor; The DC power supply is connected to the non-inverting input terminal of the operational amplifier through the first resistor, the second resistor and the fourth resistor in sequence; the DC power supply is connected to the ground through the first resistor, the second resistor and the third resistor in sequence; The second resistor is an adjustable resistor; The third resistor is a thermistor; The third resistor is a negative temperature coefficient thermistor; The voltage divider circuit includes: a fifth resistor and a sixth resistor, and the LED driving power supply also includes a seventh resistor; The DC power supply is connected to the reverse input terminal of the operational amplifier through the fifth resistor and the seventh resistor in sequence; the DC power supply is connected to the ground through the fifth resistor and the sixth resistor in sequence; The voltage stabilizing circuit comprises: an eighth resistor and a voltage stabilizing diode; the output end of the operational amplifier is connected to the PWM controller via the eighth resistor, and the operational amplifier is grounded via the eighth resistor; It also includes a ninth resistor, and the in-phase input terminal of the operational amplifier is connected to the output terminal of the operational amplifier through the ninth resistor; A tenth resistor is also included, and the inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier through the tenth resistor.

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