LED power supply with temperature safety protection

Abstract

The utility model discloses an LED power supply with temperature safety protection. The LED power supply comprises a power output module, a temperature detection module, a signal unidirectional module, a voltage detection module, a current detection module and a constant-voltage and constant-current control module. The signal one-way module can output a current signal A to the voltage detection module and a current signal B to the current detection module when the temperature detection module detects that the temperature exceeds a preset value, and outputs an adjusting signal FB to the power output module through the constant-voltage and constant-current control module, so as to reduce the voltage and / or current output to the load; by detecting the temperature of the key element in the power supply, the output voltage and / or current are automatically adjusted and reduced, the total power output by the power supply is reduced, the loss power of the power supply during working is also reduced, the temperature of the key element is enabled to be within a safe area, and the power supply is enabled not to be interrupted and damaged.

Description

Technical Field

[0001] The utility model relates to the field of LED switching power supplies, in particular to an LED power supply with temperature safety protection. Background Art

[0002] Traditional LED switching power supplies are designed to output a set voltage and current to light up the LED lamp bead module under specific usage conditions. When the temperature at the power supply installation location rises abnormally or dust increases, affecting heat dissipation, or the fan of the power supply itself is damaged, the temperature of the internal IC or high-power components of the power supply will be too high, causing damage to the power supply components or excessively high surface temperature of the power supply, which will cause lighting interruption or cause component overheating, smoking and fire, etc., especially in critical lighting occasions, such as underground passage lighting and tunnel lighting, as well as hazardous goods occasions, such as gas stations and chemical workshop lighting, which require better power supplies. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides an LED power supply with temperature safety protection.

[0004] An embodiment of the utility model adopts a technical solution to solve the technical problem: an LED power supply with temperature safety protection, including a power output module, a temperature detection module, a signal unidirectional module, a voltage detection module, a current detection module and a constant voltage and constant current control module;

[0005] The input end of the power output module is connected to an external power supply;

[0006] The temperature detection module is connected to the input end of the signal unidirectional module and is used to detect the temperature of the key temperature element in the power supply;

[0007] The first output end of the signal unidirectional module is connected to the voltage detection module, and the second output end is connected to the current detection module;

[0008] The voltage detection module is connected to the first output terminal of the power output module and one end of the load respectively, and the current detection module is connected to the second output terminal of the power output module and the other end of the load respectively;

[0009] The constant voltage and constant current control module is connected to the voltage detection module and the current detection module respectively, and the output adjustment signal FB is connected to the power output module;

[0010] The signal unidirectional module can output current signal A to the voltage detection module and output current signal B to the current detection module when the temperature detection module detects that the temperature exceeds the preset value, and output adjustment signal FB to the power output module through the constant voltage and constant current control module to reduce the voltage and / or current output to the load.

[0011] As one of the preferred embodiments of the present utility model, the power output module includes an inductor L1, a switching transistor QP, a switching transistor QF, a diode DP, a diode DF, a capacitor EC1, a capacitor EC2, a resistor RS2, a resistor RS3, a main control chip IC1, and a transformer T1;

[0012] One end of the inductor L1 is connected to one end of the rectified external power supply. The other end of the inductor L1 is respectively connected to the anode of the diode DP and the input end of the switching transistor QP. The cathode of the diode DP is respectively connected to one end of the capacitor EC1, the main control chip IC1, and one end of the primary winding of the transformer T1. The control end of the switching transistor QP is connected to the main control chip IC1. The output end of the switching transistor QP is respectively connected to one end of the resistor RS2 and the main control chip IC1. The other end of the resistor RS2 is respectively connected to the other end of the external power supply, the other end of the capacitor EC1, one end of the resistor RS3, and the GND terminal;

[0013] The input end of the switching transistor QF is connected to the other end of the primary winding of the transformer T1, the control end is connected to the main control chip IC1, and the output end is respectively connected to the main control chip IC1 and the other end of the resistor RS3;

[0014] One end of the secondary winding of the transformer T1 is connected to one end of the capacitor EC2 and the subsequent circuit through the diode DF. The other end of the secondary winding of the transformer T1 is respectively connected to the other end of the capacitor EC2 and the subsequent circuit.

[0015] As one of the preferred embodiments of the present utility model, the constant voltage and constant current control module includes an operational amplifier UV, an operational amplifier UI, an optocoupler OP1, a resistor R21, a resistor R22, a resistor R31, a resistor R32, a capacitor C21, a capacitor C31, a diode DV, and a diode DI;

[0016] The positive input end of the operational amplifier UV is connected to the reference voltage VF1. The negative input end is respectively connected to the voltage detection module and one end of the resistor R21. The output end is respectively connected to one end of the resistor R22 and one end of the capacitor C21. The other end of the resistor R21 is connected to the other end of the capacitor C21. The other end of the resistor R22 is respectively connected to one end of the light emitter of the optocoupler OP1 and the anode of the diode DI through the diode DV. The other end of the light emitter of the optocoupler OP1 is connected to the VCC terminal. Both ends of the light receiver of the optocoupler OP1 are connected to the power output module;

[0017] The positive input end of the operational amplifier UI is connected to the reference voltage VF2. The negative input end is respectively connected to the current detection module and one end of the resistor R31. The output end is respectively connected to one end of the resistor R32 and one end of the capacitor C31. The other end of the resistor R31 is connected to the other end of the capacitor C31. The other end of the resistor R32 is connected to the cathode of the diode DI.

[0018] As one of the preferred embodiments of the present utility model, the signal unidirectional module includes a first output signal path and a second output signal path. The input end of the first output signal path is respectively connected to the output end of the temperature detection module and the input end of the second output signal path; the output end of the first output signal path is connected to the voltage detection module for outputting a current signal A; the output end of the second output signal path is connected to the current detection module for outputting a current signal B.

[0019] As one of the preferred embodiments of the present utility model, the first output signal path includes a diode DA and a resistor RA. The anode of the diode DA is respectively connected to the output end of the temperature detection module and the input end of the second output signal path, and the output end of the diode DA is connected to the voltage detection module via the resistor RA.

[0020] As one of the preferred embodiments of the present utility model, the first output signal path includes a triode QA and a resistor RA. The base of the triode QA is respectively connected to the output end of the temperature detection module and the input end of the second output signal path, the emitter of the triode QA is connected to the voltage detection module via the resistor RA, and the collector of the triode QA is connected to the VCC terminal.

[0021] As one of the preferred embodiments of the present utility model, the first output signal path includes an operational amplifier UA, a diode DA and a resistor RA. The positive input terminal of the operational amplifier UA is respectively connected to the output end of the temperature detection module and the input end of the second output signal path, the output end of the operational amplifier UA is connected to the anode of the diode DA, the cathode of the diode DA is connected to the negative input terminal of the operational amplifier UA and is connected to the voltage detection module via the resistor RA.

[0022] As one of the preferred embodiments of the present utility model, the second output signal path includes a diode DB, a resistor RB, a resistor R2 and a resistor R3. One end of the resistor R2 is respectively connected to the output end of the temperature detection module and the input end of the first output signal path, the other end of the resistor R2 is connected to one end of the resistor R3 and is connected to the current detection module via the diode DB and the resistor RB, and the other end of the resistor R3 is connected to the GND terminal.

[0023] As one of the preferred embodiments of the present utility model, the second output signal path includes a triode QB, a resistor RB, a resistor R2 and a resistor R3. One end of the resistor R2 is respectively connected to the output end of the temperature detection module and the input end of the first output signal path, the other end of the resistor R2 is respectively connected to one end of the resistor R3 and the base of the triode QB, the emitter of the triode QB is connected to the current detection module via the resistor RB, the collector of the triode QB is connected to the VCC terminal, and the other end of the resistor R3 is connected to the GND terminal.

[0024] As one of the preferred embodiments of the present utility model, the second output signal path includes an operational amplifier UB, a diode DB, a resistor RB, a resistor R2, and a resistor R3. One end of the resistor R2 is respectively connected to the output end of the temperature detection module and the input end of the first output signal path. The other end of the resistor R2 is respectively connected to one end of the resistor R3 and the positive input end of the operational amplifier UB. The output end of the operational amplifier UB is connected to the anode of the diode DB. The cathode of the diode DB is connected to the negative input end of the operational amplifier UB and is connected to the current detection module via the resistor RB. The other end of the resistor R3 is connected to the GND terminal.

[0025] Advantages of the present utility model: An LED power supply with temperature safety protection includes a power output module, a temperature detection module, a signal unidirectional module, a voltage detection module, a current detection module, and a constant voltage and constant current control module. The temperature detection module is connected to the input end of the signal unidirectional module. The first output end of the signal unidirectional module is connected to the voltage detection module, and the second output end is connected to the current detection module. The signal unidirectional module can output a current signal A to the voltage detection module and a current signal B to the current detection module when the temperature detection module detects that the temperature exceeds a preset value, and output an adjustment signal FB to the power output module via the constant voltage and constant current control module to reduce the voltage and / or current output to the load. By detecting the temperature of key components inside the power supply, the output voltage and / or current is automatically adjusted and reduced, achieving a reduction in the total power output by the power supply, and at the same time reducing the power loss during the operation of the power supply, making the temperature of the key components within a safe range, so that the power supply will not interrupt operation and be damaged. Description of the Drawings

[0026] The above and / or additional aspects and advantages of the present utility model will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0027] Figure 1 is a schematic block diagram of an LED power supply with temperature safety protection;

[0028] Figure 2 is a circuit schematic diagram of the power output module;

[0029] Figure 3 is a circuit schematic diagram of the constant voltage and constant current control module;

[0030] Figure 4 is a circuit schematic diagram of the first embodiment of the signal unidirectional module;

[0031] Figure 5 is a circuit schematic diagram of the second embodiment of the signal unidirectional module;

[0032] Figure 6It is the circuit schematic diagram of the third embodiment of the signal unidirectional module;

[0033] Figure 7 It is the circuit schematic diagram of the first embodiment of the first output signal path;

[0034] Figure 8 It is the circuit schematic diagram of the second embodiment of the first output signal path;

[0035] Figure 9 It is the circuit schematic diagram of the third embodiment of the first output signal path;

[0036] Figure 10 It is the circuit schematic diagram of the first embodiment of the second output signal path;

[0037] Figure 11 It is the circuit schematic diagram of the second embodiment of the second output signal path;

[0038] Figure 12 It is the circuit schematic diagram of the third embodiment of the second output signal path. Detailed implementation manners

[0039] This part will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the drawings. The function of the drawings is to supplement the description of the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the protection scope of the present invention.

[0040] In the description of the present invention, the meaning of "a plurality of" is two or more. Understandings such as "greater than", "less than", and "exceeding" do not include the present number, and understandings such as "above", "below", and "within" include the present number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0041] In the description of the present invention, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by "up", "down", "front", "back", "left", "right", etc., is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0042] In the present utility model, unless otherwise clearly defined, terms such as "arranged", "installed", "connected", etc. shall be understood in a broad sense. For example, they can be directly connected, or indirectly connected through an intermediate medium; they can be fixedly connected, or detachably connected, or integrally formed; they can be mechanically connected; they can be the communication inside two components or the interaction relationship between two components. Those skilled in the art can reasonably determine the specific meanings of the above terms in the present utility model in combination with the specific content of the technical solution.

[0043] Referring to Figures 1 to 12 , an LED power supply with temperature safety protection includes a power output module 10, a temperature detection module 20, a signal unidirectional module 30, a voltage detection module 40, a current detection module 50, and a constant voltage and constant current control module 60;

[0044] The input end of the power output module 10 is connected to an external power supply;

[0045] The temperature detection module 20 is connected to the input end of the signal unidirectional module 30 and is used to detect the temperature on the key temperature element in the power supply;

[0046] The first output end of the signal unidirectional module 30 is connected to the voltage detection module 40, and the second output end is connected to the current detection module 50;

[0047] The voltage detection module 40 is respectively connected to the first output end of the power output module 10 and one end of the load, and the current detection module 50 is respectively connected to the second output end of the power output module 10 and the other end of the load;

[0048] The constant voltage and constant current control module 60 is respectively connected to the voltage detection module 40 and the current detection module 50, and the output adjustment signal FB is connected to the power output module 10;

[0049] When the temperature detection module 20 detects that the temperature exceeds the preset value, the signal unidirectional module 30 can output a current signal A to the voltage detection module 40, output a current signal B to the current detection module 50, and output an adjustment signal FB to the power output module 10 through the constant voltage and constant current control module 60 to reduce the current output to the load.

[0050] In the present utility model, the working principle is as follows:

[0051] 1) Referring to Figure 1 , specifically, the temperature detection module 20 is connected to the signal unidirectional module 30. The signal unidirectional module 30 divides the signal into two paths. One path is connected to the Vi node of the voltage detection module 40, and the other path is connected to the Ii node of the current detection module 50. The node Vi and the node Ii are connected to the constant voltage and constant current control module 60;

[0052] Among them, the voltage detection module 40 includes a resistor RV1 and a resistor RV2. One end of the resistor RV1 is connected to the first output end of the power output module 10. The other end of the resistor RV1 is respectively connected to the first output end of the signal unidirectional module 30, the constant voltage and constant current control module 60, and one end of the resistor RV2. The other end of the resistor RV2 is respectively connected to the current detection module 50 and the GND terminal, and is used for outputting voltage detection control; the current detection module 50 includes a resistor RI1 and a resistor RS1. One end of the resistor RI1 is respectively connected to the second output end of the signal unidirectional module 30 and the constant voltage and constant current control module 60. The other end of the resistor RI1 is respectively connected to one end of the resistor RS1 and the other end of the load. The other end of the resistor RS1 is connected to the GND terminal, and is used for outputting current detection control;

[0053] The constant voltage and constant current control module 60 connects the adjustment signal FB to the power output module 10 to form a closed-loop control.

[0054] 2) Referring to Figures 1 - 2 , in some embodiments, the power output module 10 includes an inductor L1, a switching transistor QP, a switching transistor QF, a diode DP, a diode DF, a capacitor EC1, a capacitor EC2, a resistor RS2, a resistor RS3, a main control chip IC1, and a transformer T1; one end of the inductor L1 is connected to one end of the rectified external power supply. The other end of the inductor L1 is respectively connected to the anode of the diode DP and the input end of the switching transistor QP. The cathode of the diode DP is respectively connected to one end of the capacitor EC1, the main control chip IC1, and one end of the primary winding of the transformer T1. The control end of the switching transistor QP is connected to the main control chip IC1. The output end of the switching transistor QP is respectively connected to one end of the resistor RS2 and the main control chip IC1. The other end of the resistor RS2 is respectively connected to the other end of the external power supply, the other end of the capacitor EC1, one end of the resistor RS3, and the GND terminal; the input end of the switching transistor QF is connected to the other end of the primary winding of the transformer T1, the control end is connected to the main control chip IC1, and the output end is respectively connected to the main control chip IC1 and the other end of the resistor RS3; one end of the secondary winding of the transformer T1 is connected to one end of the capacitor EC2 and the subsequent circuit through the diode DF, and the other end of the secondary winding of the transformer T1 is respectively connected to the other end of the capacitor EC2 and the subsequent circuit.

[0055] Specifically, the power supply is input from the input port. After basic rectification and filtering, it is transmitted to the PFC power factor correction circuit 11 composed of an inductor L1, a switching transistor QP, a diode DP, and a capacitor EC1, which raises the input voltage to a typical DC 400V. For an LED power supply with an input power greater than 25W, the PFC power factor correction circuit 11 is very necessary to pass the harmonic test of the electromagnetic compatibility certification; a flyback switching power supply circuit is composed of a transformer T1, a switching transistor QF, a diode DF, and a capacitor EC2. The primary winding of the transformer T1 and the switching transistor QF constitute the switching action of the input-side switching pulse. The secondary winding of the transformer T1, the diode DF, and the capacitor EC2 constitute the output pulse rectification circuit. The main control chip IC1 is connected to the output side OP1B of the optocoupler OP1. The constant voltage and constant current control module 60 transmits the control signal to the output side OP1B of the optocoupler OP1 through the input side OP1A of the optocoupler OP1. The main control chip IC1 detects the magnitude of the operating current on the output side OP1B of the optocoupler OP1, and then adjusts the duty cycle of the PWM drive signal transmitted to the control end of the switching transistor QF to achieve a stable output voltage or current value.

[0056] It should be noted that the power output module 10 is used to output a stable voltage and current. The power output module 10 is not limited to an isolated or non-isolated scheme, nor is it limited to a buck or boost scheme, and all are within the scope of the present invention.

[0057] 3) Refer to Figure 1 , in some embodiments, the temperature detection module 20 includes a thermistor NTC and a resistor R1. The thermistor NTC is installed on the key temperature element inside the power supply and one end is connected to the VCC terminal, and the other end is respectively connected to the signal unidirectional module 30 and one end of the resistor R1. The other end of the resistor R1 is connected to the GND terminal.

[0058] Specifically, the key temperature element of the power supply is selected through testing during product design. The temperature detection module 20 is used to detect the actual operating temperature of the key temperature element. The thermistor NTC and the resistor R1 are connected in series to a stable voltage VCC. At different temperatures, the actual resistance value of the thermistor NTC changes, and a voltage signal Vt reflecting the temperature can be output.

[0059] 4) Refer to Figure 1 and Figure 3, in some embodiments, the constant voltage and constant current control module 60 includes an operational amplifier UV, an operational amplifier UI, an optocoupler OP1, a resistor R21, a resistor R22, a resistor R31, a resistor R32, a capacitor C21, a capacitor C31, a diode DV, and a diode DI; the non-inverting input terminal of the operational amplifier UV is connected to a reference voltage VF1, the inverting input terminal is respectively connected to the voltage detection module 40 and one end of the resistor R21, the output terminal is respectively connected to one end of the resistor R22 and one end of the capacitor C21, the other end of the resistor R21 is connected to the other end of the capacitor C21, the other end of the resistor R22 is respectively connected to one end of the light-emitting device of the optocoupler OP1 and the anode of the diode DI through the diode DV, the other end of the light-emitting device of the optocoupler OP1 is connected to the VCC terminal, and both ends of the light-receiving device of the optocoupler OP1 are connected to the power output module 10; the non-inverting input terminal of the operational amplifier UI is connected to a reference voltage VF2, the inverting input terminal is respectively connected to the current detection module 50 and one end of the resistor R31, the output terminal is respectively connected to one end of the resistor R32 and one end of the capacitor C31, the other end of the resistor R31 is connected to the other end of the capacitor C31, and the other end of the resistor R32 is connected to the cathode of the diode DI.

[0060] Specifically, the voltage signal VS output by the voltage detection module 40 is input to the inverting input terminal of the operational amplifier UV inside the constant voltage and constant current control module 60. The operational amplifier UV functions as a comparator in this circuit. The voltage VS and a set reference voltage VF1 are simultaneously input to the operational amplifier UV. After the magnitude comparison inside the operational amplifier UV, the output signal passes through the resistor R22, the diode DV, and is connected to the power supply VCC through the input side OP1A of the optocoupler OP1. The control signal finally passes through the light-emitting diode inside the input side OP1A of the optocoupler OP1, is transmitted through light to the photosensitive triode on the output side OP1B of the optocoupler OP1, and the current on the photosensitive triode on the output side OP1B of the optocoupler OP1 is injected into the main control chip IC1 of the power output module 10. The main control chip IC1 outputs an adjusted PWM signal to control the operation of the switching transistor QF, and at the same time, the voltage of the output ports U+ / U- is controlled. The capacitor C21 and the resistor 21 form a basic loop compensation circuit to make the circuit work more stably.

[0061] Similarly, the voltage signal IS output by the current detection unit 50 is input to the inverting input terminal of the operational amplifier UI inside the constant voltage and constant current control module 60. The operational amplifier UI functions as a comparator in this circuit. The voltage IS and a set reference voltage VF2 are simultaneously input to the operational amplifier UI. After the magnitude comparison inside the operational amplifier UI, the output signal passes through the resistor R32, the diode DI, and is connected to the power supply VCC through the input side OP1A of the optocoupler OP1. The control signal finally passes through the light-emitting diode inside the input side OP1A of the optocoupler OP1, and is transmitted through light to the photosensitive triode on the output side OP1B of the optocoupler OP1. The current on the photosensitive triode on the output side OP1B of the optocoupler OP1 is injected into the main control chip IC1 of the power output module 10. The main control chip IC1 outputs an adjusted PWM signal to control the operation of the switching tube QF, and at the same time, the current of the output ports U+ / U- is controlled; the capacitor C31 and the resistor 31 form a basic loop compensation circuit to make the circuit work more stably.

[0062] 5) Refer to Figure 1 、 Figures 4 - 6 and

[0063] ① As the first embodiment of the signal unidirectional module 30, refer to Figure 1 、 Figure 4 、 Figure 7 and Figure 10 and

[0064] Specifically, the voltage Vt output by the temperature detection module 20 is input to the signal unidirectional module 30. After passing through the signal unidirectional module 30, two current signals are output. One is the current signal A output through the diode DA and the resistor RA, and the other is the current signal B output through the resistors R2 and R3 for voltage division and then through the diode DB and the resistor RB. In this circuit, the diodes DA and DB perform the signal unidirectional function.

[0065] ② As the second embodiment of the signal unidirectional module 30, refer to Figure 1 、 Figure 5 、 Figure 8 and Figure 11 . The first output signal path 31 includes the triode QA and the resistor RA. The base of the triode QA is respectively connected to the output terminal of the temperature detection module 20 and the input terminal of the second output signal path 32. The emitter of the triode QA is connected to the voltage detection module 40 through the resistor RA, and the collector of the triode QA is connected to the VCC terminal. The second output signal path 32 includes the triode QB, the resistor RB, the resistor R2, and the resistor R3. One end of the resistor R2 is respectively connected to the output terminal of the temperature detection module 20 and the input terminal of the first output signal path 31. The other end of the resistor R2 is respectively connected to one end of the resistor R3 and the base of the triode QB. The emitter of the triode QB is connected to the current detection module 50 through the resistor RB, the collector of the triode QB is connected to the VCC terminal, and the other end of the resistor R3 is connected to the GND terminal.

[0066] Specifically, the voltage Vt output by the temperature detection module 20 is input to the signal unidirectional module 30. After passing through the signal unidirectional module 30, two current signals are output. One is the current signal A output through the triode QA and the resistor RA, and the other is the current signal B output through the resistors R2 and R3 for voltage division and then through the triode QB and the resistor RB. In this circuit, the triodes QA and QB perform the signal unidirectional function and also have the function of signal buffering and amplification.

[0067] ③ As the third embodiment of the signal unidirectional module 30, refer to Figure 1 、 Figure 6 、 Figure 9 and Figure 12, the first output signal path 31 includes an operational amplifier UA, a diode DA, and a resistor RA. The positive input terminal of the operational amplifier UA is respectively connected to the output terminal of the temperature detection module 20 and the input terminal of the second output signal path 32. The output terminal of the operational amplifier UA is connected to the anode of the diode DA. The cathode of the diode DA is connected to the negative input terminal of the operational amplifier UA and is connected to the voltage detection module 40 via the resistor RA. The second output signal path 32 includes an operational amplifier UB, a diode DB, a resistor RB, a resistor R2, and a resistor R3. One end of the resistor R2 is respectively connected to the output terminal of the temperature detection module 20 and the input terminal of the first output signal path 31. The other end of the resistor R2 is respectively connected to one end of the resistor R3 and the positive input terminal of the operational amplifier UB. The output terminal of the operational amplifier UB is connected to the anode of the diode DB. The cathode of the diode DB is connected to the negative input terminal of the operational amplifier UB and is connected to the current detection module 50 via the resistor RB. The other end of the resistor R3 is connected to the GND terminal.

[0068] Specifically, the voltage Vt output by the temperature detection module 20 is input to the signal unidirectional module 30. After passing through the signal unidirectional module 30, two current signals are output. One is the current signal A output through the operational amplifier UA, the diode DA, and the resistor RA, and the other is the current signal B output through the operational amplifier UB, the diode DB, and the resistor RB after the voltage division by the resistors R2 and R3. In this circuit, the operational amplifier UA and the operational amplifier UB play a signal unidirectional function and also have a signal buffering and amplifying function, with better temperature characteristics.

[0069] ④ It should be noted that

[0070] 6) After power-on, the power output module 10 outputs voltage to the load. Under normal operating conditions, when the temperature on the thermistor NTC in the temperature detection module 20 does not exceed the designed value, the Vt voltage is relatively low, and the Vt voltage is lower than the voltages at the nodes Vi and Ii respectively. Then the signal unidirectional module 30 will not output the current signal A and the current signal B, and the state mode is:

[0071] The signal unidirectional module 30 forms an open-circuit relationship mode with the voltage detection module 40;

[0072] The signal unidirectional module 30 forms an open-circuit relationship mode with the current detection module 50;

[0073] The voltage detection module 40 divides the output voltage into Vi and feeds it back to the constant voltage and constant current control module 60. The constant voltage and constant current control module 60 outputs an adjustment signal FB to the power output module 10 to complete the closed-loop control of the output voltage. The basic result is to output a nominal voltage value, meeting the voltage requirements under normal usage conditions;

[0074] Similarly, the current detection module 50 converts the output current into a voltage Ii through the resistor RS1 and feeds it back to the constant voltage and constant current control module 60. The constant voltage and constant current control module 60 outputs an adjustment signal FB to the power output module 10 to complete the closed-loop control of the output current. As a result, the nominal current value is output, meeting the current requirements under normal operating conditions.

[0075] When operating under abnormal conditions, the temperature on the thermistor NTC in the temperature detection module 20 gradually exceeds the designed value. As the temperature rises, the resistance value of the thermistor NTC becomes smaller, causing the Vt voltage to gradually increase and be transmitted to the signal unidirectional module 30.

[0076] As the Vt voltage gradually increases, the signal unidirectional module 30 will gradually output a current signal A. The higher the temperature, the greater the current, showing a certain linear relationship.

[0077] As the Vt voltage gradually increases, the signal unidirectional module 30 will gradually output a current signal B. The higher the temperature, the greater the current, showing a certain linear relationship.

[0078] The signal unidirectional module 30 forms a connection with the voltage detection module 40. The current signal A is input into the voltage detection module 40. The voltage detection module 40 feeds back the output mixed voltage signal Vi to the constant voltage and constant current control module 60. The constant voltage and constant current control module 60 outputs an adjustment signal FB to the power output module 10 to complete the closed-loop control of the output voltage. As a result, the output voltage drops proportionally. For a resistive LED lighting source module load, when the voltage drops, the output current also drops, and the output power also drops, thereby reducing the working loss power of the key components. Then its body temperature also drops, achieving temperature protection and realizing the safety protection of the entire power supply product.

[0079] Similarly, the signal unidirectional module 30 forms a connection with the current detection module 50. The current signal B is input into the current detection module 50. The current detection module 50 outputs the mixed voltage signal Ii. The voltage Ii is fed back to the constant voltage and constant current control module 60. The constant voltage and constant current control module 60 outputs an adjustment signal FB to the power output module 10 to complete the closed-loop control of the output current. As a result, the output current drops proportionally. For a resistive load, when the current drops, the output voltage also drops, and the output power also drops, thereby reducing the working temperature of the key components, achieving temperature protection, and realizing the safety protection of the entire power supply product.

[0080] 7) The advantages of the present utility model are as follows: By detecting the temperature of the key components in the power supply, the present utility model automatically adjusts and reduces the output voltage and / or current, thereby reducing the total power output by the power supply. At the same time, the loss power during the operation of the power supply is also reduced, keeping the temperature of the key components within a safe range, so that the power supply will not interrupt operation or be damaged.

[0081] Certainly, the present utility model is not limited to the above embodiments. Those skilled in the art can make equivalent deformations or substitutions without departing from the spirit of the present utility model, and these equivalent deformations and substitutions are all included within the scope defined by the claims of this application.

Claims

1. An LED power supply with temperature safety protection, characterized in that: It comprises a power output module (10), a temperature detection module (20), a signal unidirectional module (30), a voltage detection module (40), a current detection module (50) and a constant voltage and constant current control module (60); The input end of the power output module (10) is connected to an external power supply; The temperature detection module (20) is connected to the input end of the signal unidirectional module (30) and is used to detect the temperature of a key temperature element in the power supply; The first output end of the signal unidirectional module (30) is connected to the voltage detection module (40), and the second output end is connected to the current detection module (50); The voltage detection module (40) is respectively connected to the first output end of the power output module (10) and one end of the load, and the current detection module (50) is respectively connected to the second output end of the power output module (10) and the other end of the load; The constant voltage and constant current control module (60) is connected to the voltage detection module (40) and the current detection module (50) respectively, and the output adjustment signal FB is connected to the power output module (10); The signal unidirectional module (30) can output a current signal A to the voltage detection module (40), output a current signal B to the current detection module (50) when the temperature detection module (20) detects that the temperature exceeds a preset value, and output an adjustment signal FB to the power output module (10) via the constant voltage and constant current control module (60) to reduce the voltage and / or current output to the load.

2. The LED power supply with temperature safety protection according to claim 1, characterized in that: The power output module (10) comprises an inductor L1, a switch tube QP, a switch tube QF, a diode DP, a diode DF, a capacitor EC1, a capacitor EC2, a resistor RS2, a resistor RS3, a main control chip IC1 and a transformer T1; One end of the inductor L1 is connected to one end of the external power supply after rectification, the other end of the inductor L1 is respectively connected to the anode of the diode DP and the input end of the switch tube QP, the cathode of the diode DP is respectively connected to one end of the capacitor EC1, the main control chip IC1 and one end of the primary winding of the transformer T1, the control end of the switch tube QP is connected to the main control chip IC1, the output end of the switch tube QP is respectively connected to one end of the resistor RS2 and the main control chip IC1, and the other end of the resistor RS2 is respectively connected to the other end of the external power supply, the other end of the capacitor EC1, one end of the resistor RS3 and the GND end; The input end of the switch tube QF is connected to the other end of the primary winding of the transformer T1, the control end is connected to the main control chip IC1, and the output end is connected to the main control chip IC1 and the other end of the resistor RS3 respectively; One end of the secondary winding of the transformer T1 is connected to one end of the capacitor EC2 and the subsequent circuit via the diode DF, and the other end of the secondary winding of the transformer T1 is connected to the other end of the capacitor EC2 and the subsequent circuit respectively.

3. The LED power supply with temperature safety protection according to claim 1, characterized in that: The constant voltage and constant current control module (60) comprises an operational amplifier UV, an operational amplifier UI, an optical coupler OP1, a resistor R21, a resistor R22, a resistor R31, a resistor R32, a capacitor C21, a capacitor C31, a diode DV, and a diode DI; The positive input end of the operational amplifier UV is connected to the reference voltage VF1, the reverse input end is respectively connected to the voltage detection module (40) and one end of the resistor R21, the output end is respectively connected to one end of the resistor R22 and one end of the capacitor C21, the other end of the resistor R21 is connected to the other end of the capacitor C21, the other end of the resistor R22 is respectively connected to one end of the optical coupler OP1 light emitter and the anode of the diode DI via the diode DV, the other end of the optical coupler OP1 light emitter is connected to the VCC end, and the two ends of the optical coupler OP1 light receiver are connected to the power output module (10); The positive input terminal of the operational amplifier UI is connected to the reference voltage VF2, the reverse input terminal is respectively connected to the current detection module (50) and one end of the resistor R31, the output terminal is respectively connected to one end of the resistor R32 and one end of the capacitor C31, the other end of the resistor R31 is connected to the other end of the capacitor C31, and the other end of the resistor R32 is connected to the cathode of the diode DI.

4. The LED power supply with temperature safety protection according to claim 1, characterized in that: The signal unidirectional module (30) comprises a first output signal path (31) and a second output signal path (32); the input end of the first output signal path (31) is respectively connected to the output end of the temperature detection module (20) and the input end of the second output signal path (32); the output end of the first output signal path (31) is connected to the voltage detection module (40) for outputting the current signal A; the output end of the second output signal path (32) is connected to the current detection module (50) for outputting the current signal B.

5. The LED power supply with temperature safety protection according to claim 4, characterized in that: The first output signal path (31) comprises a diode DA and a resistor RA, the anode of the diode DA being connected to the output end of the temperature detection module (20) and the input end of the second output signal path (32) respectively, and the output end of the diode DA being connected to the voltage detection module (40) via the resistor RA.

6. The LED power supply with temperature safety protection according to claim 4, characterized in that: The first output signal path (31) comprises a transistor QA and a resistor RA, the base of the transistor QA being connected to the output end of the temperature detection module (20) and the input end of the second output signal path (32) respectively, the emitter of the transistor QA being connected to the voltage detection module (40) via the resistor RA, and the collector of the transistor QA being connected to the VCC end.

7. The LED power supply with temperature safety protection according to claim 4, characterized in that: The first output signal path (31) comprises an operational amplifier UA, a diode DA and a resistor RA, the positive input end of the operational amplifier UA being respectively connected to the output end of the temperature detection module (20) and the input end of the second output signal path (32), the output end of the operational amplifier UA being connected to the anode of the diode DA, the cathode of the diode DA being connected to the reverse input end of the operational amplifier UA and being connected to the voltage detection module (40) via the resistor RA.

8. The LED power supply with temperature safety protection according to claim 4, characterized in that: The second output signal path (32) comprises a diode DB, a resistor RB, a resistor R2 and a resistor R3, one end of the resistor R2 is respectively connected to the output end of the temperature detection module (20) and the input end of the first output signal path (31), the other end of the resistor R2 is connected to one end of the resistor R3 and is connected to the current detection module (50) via the diode DB and the resistor RB, and the other end of the resistor R3 is connected to the GND end.

9. The LED power supply with temperature safety protection according to claim 4, characterized in that: The second output signal path (32) comprises a transistor QB, a resistor RB, a resistor R2 and a resistor R3, one end of the resistor R2 is respectively connected to the output end of the temperature detection module (20) and the input end of the first output signal path (31), the other end of the resistor R2 is respectively connected to one end of the resistor R3 and the base of the transistor QB, the emitter of the transistor QB is connected to the current detection module (50) via the resistor RB, the collector of the transistor QB is connected to the VCC terminal, and the other end of the resistor R3 is connected to the GND terminal.

10. The LED power supply with temperature safety protection according to claim 4, characterized in that: The second output signal path (32) comprises an operational amplifier UB, a diode DB, a resistor RB, a resistor R2 and a resistor R3, one end of the resistor R2 is respectively connected to the output end of the temperature detection module (20) and the input end of the first output signal path (31), the other end of the resistor R2 is respectively connected to one end of the resistor R3 and the positive input end of the operational amplifier UB, the output end of the operational amplifier UB is connected to the anode of the diode DB, the cathode of the diode DB is connected to the reverse input end of the operational amplifier UB and is connected to the current detection module (50) via the resistor RB, and the other end of the resistor R3 is connected to the GND end.

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