Low voltage LED linear drive circuit

Abstract

The present invention discloses a low-voltage LED linear drive circuit, comprising: a shaping circuit, a load circuit, a voltage sampling circuit, a voltage control circuit, a current limiting circuit, an energy storage circuit, a first switch circuit and a second switch circuit. When the instantaneous value of the input quasi-sinusoidal voltage is low, the control voltage collected by the voltage sampling circuit is low, the voltage control circuit and the first switch circuit are turned on, the second switch circuit is turned off, and the input quasi-sinusoidal voltage and the energy storage circuit simultaneously supply power to the load circuit; when the instantaneous value of the input quasi-sinusoidal voltage is high, the control voltage collected by the voltage sampling circuit is high, the voltage control circuit and the first switch circuit are turned off, the second switch circuit is turned on, the input quasi-sinusoidal voltage supplies power to the load circuit, and charges the energy storage circuit at the same time. The present invention has a simple structure and can effectively maintain a high efficiency of the system under a low LED conduction voltage drop state.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic drive circuit control, and in particular relates to a low-voltage LED linear drive circuit. Background Art

[0002] As a new and efficient light source, LED is widely used in lighting in various fields due to its long life, low energy consumption, energy saving and environmental protection. The lighting of LED requires a driving circuit. However, the existing driving circuit has low efficiency under the condition of low LED conduction voltage drop. Higher loss is dissipated in the constant current device, and the reliability of the system is very poor. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a low-voltage LED linear drive circuit, which can directly drive low-voltage LED lamp beads, save system costs, and improve the overall efficiency of the system, thereby improving the reliability of the system.

[0004] In order to achieve the above object, the technical solution of the present invention is as follows:

[0005] Low voltage LED linear drive circuit, including:

[0006] A shaping circuit is used to rectify the input AC full-wave into a quasi-sinusoidal voltage;

[0007] a load circuit including one or more LEDs connected in series;

[0008] A voltage sampling circuit is connected between V+ and V- of the input quasi-sinusoidal voltage, and is used to collect the control voltage, thereby controlling the on and off of the voltage control circuit;

[0009] a voltage control circuit connected in series with the load circuit and connected in parallel with the energy storage circuit via a second switch circuit;

[0010] A current limiting circuit is connected in series with the load circuit. After the load circuit and the current limiting circuit are connected in series, they are then connected in parallel with the first switch circuit. The current limiting circuit is used to limit the current value flowing through the load circuit.

[0011] When the instantaneous value of the input quasi-sinusoidal voltage is low, the control voltage collected by the voltage sampling circuit is low, the voltage control circuit and the first switch circuit are turned on, the second switch circuit is turned off, and the input quasi-sinusoidal voltage and the energy storage circuit simultaneously supply power to the load circuit;

[0012] When the instantaneous value of the input quasi-sinusoidal voltage is high, the control voltage collected by the voltage sampling circuit is high, the voltage control circuit and the first switch circuit are turned off, the second switch circuit is turned on, and the input quasi-sinusoidal voltage powers the load circuit and charges the energy storage circuit at the same time.

[0013] The low-voltage LED linear drive circuit of the present invention has a simple structure and can effectively maintain a higher efficiency of the system under a lower LED conduction voltage drop state.

[0014] On the basis of the above technical solution, the following improvements can be made:

[0015] As a preferred solution, the first switching circuit includes: a diode D1, and the second switching circuit includes: a diode D2; the anode of the diode D1 is respectively connected to the cathode of the diode D2 and the energy storage circuit, and the cathode of the diode D1 is connected to the load circuit; the anode of the diode D2 is respectively connected to the current limiting circuit and the voltage control circuit, and the cathode of the diode D2 is respectively connected to the anode of the diode D1 and the energy storage circuit.

[0016] The above preferred solution has a simple structure and low component cost.

[0017] As a preferred solution, the voltage control circuit is implemented by a voltage-controlled current limiting circuit, and the current limiting value of the voltage-controlled current limiting circuit decreases as the control voltage increases.

[0018] The above preferred solution has a simple structure and safe and reliable working state conversion.

[0019] As a preferred solution, the voltage-controlled current limiting circuit includes: a voltage-controlled constant current source I1 and a current-limiting sampling resistor R; the control voltage can control the magnitude of the output current of the voltage-controlled constant current source I1.

[0020] The above preferred solution has a simple structure, high circuit safety performance and good control effect.

[0021] As a preferred solution, the voltage-controlled constant current source I1 and the current-limiting sampling resistor R are connected in series, and the series-connected voltage-controlled constant current source I1 and the current-limiting sampling resistor R are then connected in parallel with the energy storage circuit.

[0022] The above preferred solution is adopted, and the structure is simple.

[0023] As a preferred solution, the constant current source I1 is connected in parallel with the energy storage circuit and then connected in series with the current limiting sampling resistor R.

[0024] The above preferred solution has a simple structure, high circuit safety performance and a current switching protection function.

[0025] As a preferred solution, the voltage control circuit is implemented by a voltage-controlled resistor circuit, and the resistance value of the voltage-controlled resistor circuit increases with the increase of the control voltage.

[0026] The above preferred solution has a simple structure and low cost.

[0027] As a preferred solution, the voltage-controlled resistor circuit includes: an NMOS transistor MN101, an NMOS transistor MN102 and a resistor R3;

[0028] The source of MN101 is connected to the input quasi-sinusoidal voltage V- and the source of MN102 respectively, the gate thereof is connected to the control voltage, and the drain thereof is connected to the gate of MN102 and the resistor R3 respectively;

[0029] The source of MN102 is connected to the input quasi-sinusoidal voltage V- and the source of MN101 respectively, the gate thereof is connected to the drain of MN101 and the resistor R3 respectively, and the drain thereof is connected to the load circuit and the positive electrode of the diode D2 respectively;

[0030] One end of the resistor R3 is connected to the drain of MN101 and the gate of MN102 respectively, and the other end thereof is connected to the internal power supply Vdc.

[0031] The above preferred solution has a simple structure, uses simple components and has low cost.

[0032] As a preferred solution, the voltage sampling circuit includes: a resistor R1 and a resistor R2 connected in series, and the output voltage between the resistor R1 and the resistor R2 is the control voltage.

[0033] By adopting the above preferred solution, the performance of the circuit is more stable.

[0034] As a preferred solution, the energy storage circuit is one or more capacitors C connected in parallel.

[0035] By adopting the above preferred solution, when multiple capacitors C are connected in parallel, the amount of electricity stored is greater. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A module diagram of a low-voltage LED linear drive circuit provided in an embodiment of the present invention.

[0037] Figure 2 This is one of the circuit diagrams of the low-voltage LED linear drive circuit provided by the embodiment of the present invention.

[0038] Figure 3 A curve diagram showing the change of the current limit value (I_VCS) with the control voltage (Vc) in the voltage-controlled current limiting circuit provided in an embodiment of the present invention.

[0039] Figure 4 The second circuit diagram of the low-voltage LED linear drive circuit provided in the embodiment of the present invention.

[0040] Figure 5 The third circuit diagram of the low-voltage LED linear drive circuit provided in the embodiment of the present invention.

[0041] Figure 6 The fourth circuit diagram of the low-voltage LED linear drive circuit provided in the embodiment of the present invention.

[0042] Figure 7 The fifth circuit diagram of the low-voltage LED linear drive circuit provided in the embodiment of the present invention.

[0043] Figure 8 A curve diagram showing the variation of the resistance value (R_VCS) of the voltage-controlled resistor circuit provided in an embodiment of the present invention with the control voltage (Vc).

[0044] Fig. 9 Circuit diagram six of the low-voltage LED linear drive circuit provided in an embodiment of the present invention.

[0045] Fig.10 This is circuit diagram seven of the low-voltage LED linear drive circuit provided in an embodiment of the present invention.

[0046] Among them: 1. Shaping circuit, 2. Load circuit, 3. Voltage sampling circuit, 4. Voltage control circuit, 5. Current limiting circuit, 6. Energy storage circuit, 7. First switch circuit, 8. Second switch circuit. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0048] In order to achieve the purpose of the present invention, some embodiments of the low-voltage LED linear drive circuit, such as Figure 1 As shown, the low voltage LED linear drive circuit includes:

[0049] A shaping circuit 1, used for rectifying the input alternating current into a quasi-sinusoidal voltage;

[0050] A load circuit 2, comprising a plurality of LEDs connected in series;

[0051] A voltage sampling circuit 3 is connected between V+ and V- of the input quasi-sinusoidal voltage, and is used to collect the control voltage, thereby controlling the on and off of the voltage control circuit 4;

[0052] a voltage control circuit 4, which is connected in series with the load circuit 2 and in parallel with the energy storage circuit 6 via a second switch circuit 8;

[0053] A current limiting circuit 5 is connected in series with the load circuit 2. After the load circuit 2 is connected in series with the current limiting circuit 5, it is connected in parallel with the first switch circuit 7. The current limiting circuit 5 is used to limit the current value flowing through the load circuit 2;

[0054] When the instantaneous value of the input quasi-sinusoidal voltage is low, the control voltage collected by the voltage sampling circuit 3 is low, the voltage control circuit 4 and the first switch circuit 7 are turned on, the second switch circuit 8 is turned off, and the input quasi-sinusoidal voltage and the energy storage circuit 6 simultaneously supply power to the load circuit 2;

[0055] When the instantaneous value of the input quasi-sinusoidal voltage is high, the control voltage collected by the voltage sampling circuit 3 is high, the voltage control circuit 4 and the first switch circuit 7 are turned off, the second switch circuit 8 is turned on, and the input quasi-sinusoidal voltage supplies power to the load circuit 2 and charges the energy storage circuit 6 at the same time.

[0056] like Figure 2 As shown, the first switch circuit 7 includes: a diode D1, and the second switch circuit 8 includes: a diode D2; the anode of the diode D1 is respectively connected to the cathode of the diode D2 and the energy storage circuit 6, and the cathode of the diode D1 is connected to the load circuit 2; the anode of the diode D2 is respectively connected to the current limiting circuit 5 and the voltage control circuit 4, and the cathode of the diode D2 is respectively connected to the anode of the diode D1 and the energy storage circuit 6.

[0057] The energy storage circuit 6 is a capacitor C.

[0058] The low-voltage LED linear drive circuit of the present invention has a simple structure, and a quasi-sinusoidal voltage is present between V+ and V- after full-wave rectification of alternating current.

[0059] When the instantaneous value of the input quasi-sinusoidal voltage is low, the control voltage collected by the voltage sampling circuit 3 is low, the voltage control circuit 4 and the diode D1 are turned on, the diode D2 is turned off, and the input quasi-sinusoidal voltage and the capacitor C simultaneously power the LED; when the instantaneous value of the input quasi-sinusoidal voltage is high, the control voltage collected by the voltage sampling circuit 3 is high, the voltage control circuit 4 and the diode D1 are turned off, the diode D2 is turned on, the input quasi-sinusoidal voltage powers the LED and charges the capacitor C at the same time.

[0060] The present invention uses simple components to realize the driving of LEDs, and can effectively maintain a high efficiency of the system under a low LED conduction voltage drop state.

[0061] like Figure 3 As shown, in order to further optimize the implementation effect of the present invention, in some other embodiments, the remaining characteristic technologies are the same, the difference is that the voltage control circuit 4 is implemented by a voltage-controlled current limiting circuit 5, and the current limiting value of the voltage-controlled current limiting circuit 5 decreases with the increase of the control voltage.

[0062] The above preferred solution is adopted, and the structure is simple.

[0063] like Figure 4As shown, further, the voltage-controlled current limiting circuit 5 includes: a voltage-controlled constant current source I1 and a current-limiting sampling resistor R; the control voltage can control the magnitude of the output current of the voltage-controlled constant current source I1. The voltage-controlled constant current source I1 and the current-limiting sampling resistor R are connected in series, and the series-connected voltage-controlled constant current source I1 and the current-limiting sampling resistor R are then connected in parallel with the capacitor C.

[0064] The above preferred solution is adopted, and the structure is simple. Figure 5 The specific circuit structure of the voltage-controlled current limiting circuit 5 is further shown.

[0065] like Figure 6 As shown, in order to further optimize the implementation effect of the present invention, in some other embodiments, the remaining characteristic technologies are the same, the difference is that the voltage control circuit 4 is implemented by a voltage-controlled current limiting circuit 5, and the current limiting value of the voltage-controlled current limiting circuit 5 decreases with the increase of the control voltage.

[0066] The voltage-controlled current limiting circuit 5 includes: a voltage-controlled constant current source I1 and a current-limiting sampling resistor R; the control voltage can control the magnitude of the output current of the voltage-controlled constant current source I1. The voltage-controlled constant current source I1 is connected in parallel with the capacitor C and then in series with the current-limiting sampling resistor R.

[0067] The above preferred solution has a simple structure, high circuit safety performance and a current switching protection function. Figure 7 The specific circuit structure of the voltage-controlled current limiting circuit 5 is further shown.

[0068] like Figure 8 As shown, in order to further optimize the implementation effect of the present invention, in some other implementations, the remaining characteristic technologies are the same, the difference is that the voltage control circuit 4 is implemented by a voltage-controlled resistor circuit, and the resistance value of the voltage-controlled resistor circuit increases with the increase of the control voltage.

[0069] The above preferred solution has a simple structure and low cost.

[0070] like Fig. 9 As shown, further, the voltage-controlled resistor circuit includes: an NMOS transistor MN101, an NMOS transistor MN102 and a resistor R3;

[0071] The source of MN101 is connected to the input quasi-sinusoidal voltage V- and the source of MN102 respectively, the gate thereof is connected to the control voltage, and the drain thereof is connected to the gate of MN102 and the resistor R respectively;

[0072] The source of MN102 is connected to the input quasi-sinusoidal voltage V- and the source of MN101 respectively, the gate thereof is connected to the drain of MN101 and the resistor R3 respectively, and the drain thereof is connected to the load circuit 2 and the positive electrode of the diode D2 respectively;

[0073] One end of the resistor R3 is connected to the drain of MN101 and the gate of MN102 respectively, and the other end thereof is connected to the internal power supply Vdc.

[0074] The above preferred solution has a simple structure and uses simple components and low cost compared with the voltage-controlled current limiting circuit 5 .

[0075] like Fig.10 As shown, in order to further optimize the implementation effect of the present invention, in some other implementations, the remaining characteristic technologies are the same, except that the current limiting circuit 5 specifically includes: an amplifier, a power tube and a current limiting sampling resistor R.

[0076] By adopting the above preferred solution, the performance of the circuit is more stable.

[0077] In order to further optimize the implementation effect of the present invention, in some other embodiments, the remaining characteristic technologies are the same, except that, Figure 1 As shown, the voltage sampling circuit 3 includes: a resistor R1 and a resistor R2 connected in series, and the output voltage between the resistor R1 and the resistor R2 is the control voltage.

[0078] By adopting the above preferred solution, the structure is simple and the performance of the circuit is more stable.

[0079] In order to further optimize the implementation effect of the present invention, in some other implementations, the remaining characteristic technologies are the same, except that the energy storage circuit 6 is a plurality of capacitors C connected in parallel.

[0080] The above preferred solution has a simple structure and a larger power storage capacity.

[0081] Regarding the preferred embodiments of the present invention, it should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. Low voltage LED linear drive circuit, including: A shaping circuit is used to rectify the input AC full-wave into a quasi-sinusoidal voltage; a load circuit including one or more LEDs connected in series; It is characterized by further comprising: A voltage sampling circuit is connected between V+ and V- of the input quasi-sinusoidal voltage, and is used to collect the control voltage, thereby controlling the on and off of the voltage control circuit; a voltage control circuit connected in series with the load circuit and connected in parallel with the energy storage circuit via a second switch circuit; A current limiting circuit is connected in series with the load circuit. After the load circuit is connected in series with the current limiting circuit, it is connected in parallel with the first switch circuit. The current limiting circuit is used to limit the current value flowing through the load circuit; When the instantaneous value of the input quasi-sinusoidal voltage is low, the control voltage collected by the voltage sampling circuit is low, the voltage control circuit and the first switch circuit are turned on, the second switch circuit is turned off, and the input quasi-sinusoidal voltage and the energy storage circuit simultaneously supply power to the load circuit; When the instantaneous value of the input quasi-sinusoidal voltage is high, the control voltage collected by the voltage sampling circuit is high, the voltage control circuit and the first switch circuit are turned off, the second switch circuit is turned on, and the input quasi-sinusoidal voltage supplies power to the load circuit and charges the energy storage circuit at the same time; The voltage control circuit is implemented by a voltage-controlled resistor circuit, and the resistance value of the voltage-controlled resistor circuit increases as the control voltage increases; When the voltage control circuit is implemented by a voltage-controlled resistor circuit, the voltage-controlled resistor circuit includes: an NMOS transistor MN101, an NMOS transistor MN102 and a resistor R3; The source of MN101 is connected to the input quasi-sinusoidal voltage V- and the source of MN102 respectively, the gate thereof is connected to the control voltage, and the drain thereof is connected to the gate of MN102 and the resistor R3 respectively; The source of MN102 is connected to the input quasi-sinusoidal voltage V- and the source of MN101 respectively, the gate thereof is connected to the drain of MN101 and the resistor R3 respectively, and the drain thereof is connected to the load circuit and the positive electrode of the diode D2 respectively; One end of the resistor R3 is connected to the drain of MN101 and the gate of MN102 respectively, and the other end thereof is connected to the internal power supply Vdc; The voltage sampling circuit comprises: a resistor R1 and a resistor R2 connected in series, and the output voltage between the resistor R1 and the resistor R2 is the control voltage; The energy storage circuit is one or more capacitors C connected in parallel.

2. The low voltage LED linear drive circuit according to claim 1, characterized in that: The first switch circuit includes: a diode D1, and the second switch circuit includes: a diode D2; The anode of the diode D1 is connected to the cathode of the diode D2 and the energy storage circuit respectively, and the cathode of the diode D1 is connected to the load circuit; The anode of the diode D2 is connected to the current limiting circuit and the voltage control circuit respectively, and the cathode of the diode D2 is connected to the anode of the diode D1 and the energy storage circuit respectively.

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