LED power supply PFC voltage regulation circuit

Abstract

The utility model discloses a PFC (Power Factor Correction) voltage regulation circuit of an LED (Light Emitting Diode) power supply. A topological structure of the LED power supply consists of PFC boosting, linear constant-current control and PFC voltage regulation control. PFC voltage regulation control is the specific implementation content of the scheme, an implementation circuit provides basic voltage through a VCC, a resistor R8 and a resistor R10, a resistor R9 and a resistor R11 detect the voltage of a constant-current power tube, an error integrator is composed of an operational amplifier U3 and a capacitor C4, and the integrator generates a control signal to change the gain of a PFC voltage detection circuit through a resistor R7 and a diode D4. A closed-loop control circuit is formed to adjust the PFC voltage, so that the Vf value of the lamp bead becomes high or low, and the voltage of the constant-current power tube is constant all the time. The problems that the efficiency of the LED power supply is reduced and the temperature rise of the LED power supply is increased due to the change of the Vf value of the LED lamp bead are solved, the overall implementation is simple, the cost is low, and safety and reliability are realized.

Description

Technical Field

[0001] The utility model relates to the technical field of LED power supplies, in particular to a PFC voltage regulating circuit for an LED power supply. Background Art

[0002] During the operation of LED lamps, the temperature of the lamp bead body increases, which will cause the Vf value of the lamp bead to decrease, resulting in an increase in the voltage of the constant current power tube, thereby increasing the power loss of the constant current power tube, reducing the efficiency of the LED power supply, and increasing the temperature rise of the LED power supply. Heat dissipation treatment needs to be added during design, resulting in an increase in design costs. Utility Model Content

[0003] In view of the problems existing in the prior art, the utility model discloses a PFC voltage regulating circuit for an LED power supply, comprising: 1. a diode D1, a diode D2, a bridge rectifier D3, a diode D4, an inductor L1, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, an N-channel MOS transistor Q1, an N-channel MOS transistor Q2, a linear constant current control chip U1, a PFC control chip U2, an operational amplifier U3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, and an LED lamp bead; an AC power supply is input to the bridge rectifier D3, and the bridge rectifier D3 is connected in parallel with the capacitor C1; the inductor L1 is connected in series with the diode D2 and then in parallel with the diode D1, the positive electrode of the diode D1 is connected to the capacitor C1, and the negative electrode is connected to the negative electrode of the diode D2; the negative electrode of the N-channel MOS transistor Q1 is connected to the positive electrode of the diode D2, and the negative electrode of the N-channel MOS transistor Q1 is connected to the positive electrode of the diode D2. The G terminal is connected to the GATE port of the PFC control chip U2; one end of the resistor R1 is connected to the S terminal of the N-channel MOS tube Q1, and the other end is connected to the capacitor C1; one end of the capacitor C2 is connected to the cathode of the diode D2, and the other end is connected to the capacitor C1;

[0004] The linear constant current control chip U1 port HV is connected to the cathode of the diode D2; one end of the resistor R2 is connected to the linear constant current control chip U1 port FB, and the other end is connected to the D pole of the N-channel MOS transistor Q2. The G pole of the N-channel MOS transistor Q2 is connected to the GATE port of the linear constant current control chip U1, and the S pole of the N-channel MOS transistor Q2 is connected to the CS port of the linear constant current control chip U1; one end of the resistor R3 is connected to the CS port of the linear constant current control chip U1, and the other end is connected to the capacitor C2; one end of the resistor R5 is connected to the FB port of the linear constant current control chip U1, and the other end is connected to the capacitor C2; after several LED lamp beads are connected in series, one end is connected to the D pole of the N-channel MOS transistor Q2, and the other end is connected to the HV port of the linear constant current control chip U1;

[0005] One end of capacitor C3 is connected to port VS of the PFC control chip U2, and the other end is grounded; one end of resistor R4 is connected to port VS of the PFC control chip U2, and the other end is connected to the cathode of diode D2; one end of resistor R6 is connected to port VS of the PFC control chip U2, and the other end is grounded; port CS of the PFC control chip U2 is connected to the S-pole of the N-channel MOS transistor Q1; after resistor R7 and diode D4 are connected in series, one end of resistor R7 is connected to port VS of the PFC control chip U2, and the cathode of diode D4 is connected to the output of operational amplifier U3; one end of capacitor C4 is connected to the cathode of diode D4, and the other end is connected to the inverting input of operational amplifier U3; one end of resistor R9 is connected to the non-inverting input of operational amplifier U3, and the other end is connected to the D-pole of N-channel MOS transistor Q2; one end of resistor R8 is connected to the inverting input of operational amplifier U3, and the other end is connected to VOC; after resistors R10 and R11 are connected in series, the two ends are connected to the inverting input and non-inverting input of operational amplifier U3, respectively.

[0006] As a preferred technical solution of the present invention, the bridge rectifier D3 is grounded, one port of the PFC control chip U2 is connected to VOC, and the other port is grounded.

[0007] As a preferred technical solution of the present invention, one port of the linear constant current control chip U1 is grounded.

[0008] As a preferred technical solution of the present invention, the resistor R10 and the resistor R11 are both grounded.

[0009] The beneficial effects of the utility model are as follows: the utility model provides a method for detecting the constant current power tube voltage to control the PFC voltage in a closed loop, so that the constant current power tube voltage is constant, and the problem of reduced efficiency of the LED power supply and increased temperature rise of the LED power supply caused by changes in the Vf value of the LED lamp beads is solved. The overall implementation is simple, low cost, safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the specific embodiments or the description of the prior art. In all the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0011] Figure 1 This is the circuit diagram of the utility model; DETAILED DESCRIPTION

[0012] Example 1

[0013] like Figure 1As shown, the utility model discloses a PFC voltage regulating circuit for an LED power supply, 1. It includes a diode D1, a diode D2, a bridge rectifier D3, a diode D4, an inductor L1, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, an N-channel MOS transistor Q1, an N-channel MOS transistor Q2, a linear constant current control chip U1, a PFC control chip U2, an operational amplifier U3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, and an LED lamp bead; an AC power input bridge rectifier D3, the bridge rectifier D3 is connected in parallel with the capacitor C1; the inductor L1 is connected in series with the diode D2 and then in parallel with the diode D1, the positive electrode of the diode D1 is connected to the capacitor C1, and the negative electrode is connected to the negative electrode of the diode D2; the negative electrode of the N-channel MOS transistor Q1 is connected to the positive electrode of the diode D2, and the negative electrode of the N-channel MOS transistor Q1 is connected to the positive electrode of the diode D2. The G terminal is connected to the GATE port of the PFC control chip U2; one end of the resistor R1 is connected to the S terminal of the N-channel MOS tube Q1, and the other end is connected to the capacitor C1; one end of the capacitor C2 is connected to the cathode of the diode D2, and the other end is connected to the capacitor C1;

[0014] The linear constant current control chip U1 port HV is connected to the cathode of the diode D2; one end of the resistor R2 is connected to the linear constant current control chip U1 port FB, and the other end is connected to the D pole of the N-channel MOS transistor Q2. The G pole of the N-channel MOS transistor Q2 is connected to the GATE port of the linear constant current control chip U1, and the S pole of the N-channel MOS transistor Q2 is connected to the CS port of the linear constant current control chip U1; one end of the resistor R3 is connected to the CS port of the linear constant current control chip U1, and the other end is connected to the capacitor C2; one end of the resistor R5 is connected to the FB port of the linear constant current control chip U1, and the other end is connected to the capacitor C2; after several LED lamp beads are connected in series, one end is connected to the D pole of the N-channel MOS transistor Q2, and the other end is connected to the HV port of the linear constant current control chip U1;

[0015] One end of capacitor C3 is connected to port VS of the PFC control chip U2, and the other end is grounded; one end of resistor R4 is connected to port VS of the PFC control chip U2, and the other end is connected to the cathode of diode D2; one end of resistor R6 is connected to port VS of the PFC control chip U2, and the other end is grounded; port CS of the PFC control chip U2 is connected to the S-pole of the N-channel MOS transistor Q1; after resistor R7 and diode D4 are connected in series, one end of resistor R7 is connected to port VS of the PFC control chip U2, and the cathode of diode D4 is connected to the output of operational amplifier U3; one end of capacitor C4 is connected to the cathode of diode D4, and the other end is connected to the inverting input of operational amplifier U3; one end of resistor R9 is connected to the non-inverting input of operational amplifier U3, and the other end is connected to the D-pole of N-channel MOS transistor Q2; one end of resistor R8 is connected to the inverting input of operational amplifier U3, and the other end is connected to VOC; after resistors R10 and R11 are connected in series, the two ends are connected to the inverting input and non-inverting input of operational amplifier U3, respectively.

[0016] The operating principle of this utility model is that the LED power supply topology consists of a PFC boost, linear constant current control, and PFC voltage regulation control. The PFC voltage regulation control is a specific implementation of this solution. The implementation circuit comprises VCC, resistors R8, and R10 to provide the base voltage. Resistors R9 and R11 detect the voltage of the constant current power tube. An operational amplifier U3 and capacitor C4 form an error integrator. The integrator generates a control signal that, through resistor R7 and diode D4, varies the gain of the PFC voltage detection circuit. This closed-loop control circuit adjusts the PFC voltage, increasing or decreasing the Vf value of the lamp beads while maintaining a constant voltage on the constant current power tube.

[0017] Components not described in detail herein are prior art.

[0018] Although the specific embodiments of the present invention are described in detail above, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by ordinary technicians in this field, various changes can be made without departing from the purpose of the present invention. Modifications or deformations that do not involve creative work are still within the scope of protection of the present invention.

Claims

1. A PFC voltage regulation circuit for an LED power supply, characterized by: It includes a diode D1, a diode D2, a bridge rectifier D3, a diode D4, an inductor L1, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, an N-channel MOS tube Q1, an N-channel MOS tube Q2, a linear constant current control chip U1, a PFC control chip U2, an operational amplifier U3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, and an LED lamp bead; the AC power input is a bridge rectifier D3, and the bridge rectifier D3 is connected in parallel with the capacitor C1; the inductor L1 is connected in series with the diode D2 and then in parallel with the diode D1, the positive electrode of the diode D1 is connected to the capacitor C1, and the negative electrode is connected to the negative electrode of the diode D2; the D electrode of the N-channel MOS tube Q1 is connected to the positive electrode of the diode D2, and the G electrode of the N-channel MOS tube Q1 is connected to the GATE port of the PFC control chip U2; one end of the resistor R1 is connected to the N-channel MOS tube Q1 S pole, and the other end is connected to capacitor C1; one end of capacitor C2 is connected to the cathode of diode D2, and the other end is connected to capacitor C1; the linear constant current control chip U1 port HV is connected to the cathode of diode D2; one end of resistor R2 is connected to the linear constant current control chip U1 port FB, and the other end is connected to the D pole of N-channel MOS transistor Q2, the G pole of N-channel MOS transistor Q2 is connected to the GATE port of linear constant current control chip U1, and the S pole of N-channel MOS transistor Q2 is connected to the CS port of linear constant current control chip U1; one end of resistor R3 is connected to the CS port of linear constant current control chip U1, and the other end is connected to capacitor C2; one end of resistor R5 is connected to the FB port of linear constant current control chip U1, and the other end is connected to capacitor C2; after several LED lamp beads are connected in series, one end is connected to the D pole of N-channel MOS transistor Q2, and the other end is connected to the HV port of linear constant current control chip U1; One end of capacitor C3 is connected to port VS of the PFC control chip U2, and the other end is grounded; one end of resistor R4 is connected to port VS of the PFC control chip U2, and the other end is connected to the cathode of diode D2; one end of resistor R6 is connected to port VS of the PFC control chip U2, and the other end is grounded; port CS of the PFC control chip U2 is connected to the S-pole of the N-channel MOS transistor Q1; after resistor R7 and diode D4 are connected in series, one end of resistor R7 is connected to port VS of the PFC control chip U2, and the cathode of diode D4 is connected to the output of operational amplifier U3; one end of capacitor C4 is connected to the cathode of diode D4, and the other end is connected to the inverting input of operational amplifier U3; one end of resistor R9 is connected to the non-inverting input of operational amplifier U3, and the other end is connected to the D-pole of N-channel MOS transistor Q2; one end of resistor R8 is connected to the inverting input of operational amplifier U3, and the other end is connected to VOC; after resistors R10 and R11 are connected in series, the two ends are connected to the inverting input and non-inverting input of operational amplifier U3, respectively.

2. The LED power supply PFC voltage regulation circuit according to claim 1, characterized in that: The bridge rectifier D3 is grounded. One port of the PFC control chip U2 is connected to VOC, and the other port is grounded.

3. The LED power supply PFC voltage regulation circuit according to claim 1, characterized in that: One port of the linear constant current control chip U1 is grounded.

4. The LED power supply PFC voltage regulation circuit according to claim 1, characterized in that: The resistor R10 and the resistor R11 are both grounded.

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