CN104780644B - A kind of Novel constant-flow voltage stabilizing inverse-excitation type LED drive power - Google Patents

Abstract

The present invention designs a new constant-current regulated flyback LED drive power supply, which features: (1) The current control loop adopts the integral limit saturation (Anti‑windup) algorithm based on conditional action technology to realize constant current control, and the voltage control loop Single-cycle control technology is used to realize voltage regulation control. (2) The two control loops output the PWM signal with adjustable duty ratio through the "AND" logic unit to control the turn-on and turn-off of the switch tube on the primary side of the transformer. Through the "AND" logic module, there is an "interlock" relationship between the current control loop and the voltage control loop. The constant current output is realized through the current control loop, the voltage regulation function is realized through the function of the voltage control loop, and when the output current is too high, through this "interlock" relationship, the voltage control loop will limit the voltage to a stable maximum The voltage value, thereby limiting the increase of the output current, protects the LED load. (3) A PWM dimming link is added to the input end of the "AND" logic module to realize PWM dimming.

Description

A new constant current regulated flyback LED drive power supply

technical field

The invention relates to an LED driving power supply, which belongs to the field of electronic technology, especially the field of high-frequency switching power supply.

Background technique

LED light sources have the advantages of high efficiency, long life, safety, environmental protection and energy saving, and wide color gamut. They are widely used in lighting fields such as home lighting, road lighting, and vehicle lighting, and gradually become the next-generation lighting source to replace traditional light sources. Since the LED light source is a nonlinear load and it is sensitive to the temperature of the working environment, a constant current drive method is generally used. The constant current drive can eliminate the current change caused by the forward voltage change caused by the system temperature and process lamp factors, ensure the consistency of the brightness and chromaticity of the LED light source, and can prolong the service life of the LED light source, so the LED drive power supply Generally higher constant current accuracy is required.

Traditional LED drive power generally adopts PI control based on voltage and current negative feedback. This circuit is simple and easy to implement, but has slow dynamic response, low steady-state accuracy, and weak anti-disturbance ability.

Contents of the invention

The present invention mainly aims at the traditional LED driving power generally using PI control based on voltage and current negative feedback. This kind of circuit is simple and easy to implement, but has slow dynamic response, low steady-state precision and weak anti-disturbance ability. A new type of constant current voltage regulator is designed. Flyback LED driver power supply.

The constant current controller based on the anti-windup algorithm of the conditional action technology adopts the anti-windup algorithm of the conditional action technology to realize feedback control on the sampled output current signal and achieve the purpose of constant current.

The voltage stabilizing controller based on single-cycle control technology uses single-cycle control technology to perform feedback control on the sampled output voltage signal to achieve the purpose of voltage stabilization.

Adding a PWM dimming module can adjust the PWM duty cycle of the output current at the output terminal, and realize a pulse current PWM dimming.

Add the "AND" logic module, take the constant current controller based on the conditional technology Anti-windup algorithm, the voltage regulator controller based on the single cycle control technology, and the PWM signal output by the PWM dimming module as its input signal, and output a The PWM signal after the logic "AND" operation is sent to the power switch tube to control the on and off of the power switch tube to realize the conversion of energy from the primary side to the secondary side in the flyback power conversion unit.

The beneficial effects of the present invention are:

(1) The current control loop adopts the anti-windup algorithm based on conditional action technology to realize constant current control, and the voltage control loop adopts single-cycle control technology to realize voltage stabilization control.

(2) The two control loops output the PWM signal with adjustable duty ratio through the "AND" logic unit to control the turn-on and turn-off of the switch tube on the primary side of the transformer. Through the "AND" logic module, there is an "interlock" relationship between the current control loop and the voltage control loop. The constant current output is realized through the current control loop, the voltage regulation function is realized through the function of the voltage control loop, and when the output current is too high, through this "interlock" relationship, the voltage control loop will limit the voltage to a stable maximum The voltage value, thereby limiting the increase of the output current, protects the LED load.

(3) A PWM dimming link is added to the input end of the "AND" logic module to realize PWM dimming.

Description of drawings

Figure 1 is a block diagram of the overall structure of the LED drive power supply.

Figure 2 is the LED main circuit diagram.

Figure 3 is a schematic diagram of a voltage regulator controller based on single-cycle control technology.

Figure 4 is a schematic diagram of a constant current controller based on the conditional technology Anti-windup algorithm.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, the circuit of the present invention includes: an AC input rectification filter unit, a flyback power conversion unit, an output rectification filter unit, a voltage/current sampling unit, a constant current controller based on the conditional technology Anti-windup algorithm, Voltage regulator controller, PWM dimming module, and logic module based on single-cycle control technology; the AC input rectification and filtering unit, flyback power conversion unit, output rectification and filtering unit, and voltage/current feedback sampling unit form the LED The main circuit part of the drive power supply; the constant current controller based on the conditional technology Anti-windup algorithm, the voltage regulator controller based on the single-cycle control technology, the PWM dimming module, and the "AND" logic module form the LED drive power supply. Peripheral control circuit; the AC input rectification and filtering unit converts AC mains power into DC pulse voltage and inputs it to the flyback power conversion unit; the flyback power conversion unit includes an RCD buffer circuit, a high-frequency transformer, and a power switch tube. When the high-frequency transformer is turned off, the primary side of the high-frequency transformer stores the electric energy, and when the switch tube is turned on, the high-frequency transformer transfers the electric energy to the secondary side, that is, the output terminal; the voltage/current sampling unit is responsible for sampling the voltage and current signals of the output terminal and respectively The voltage sampling signal and current sampling signal are sent to the input terminals of the voltage stabilizing controller based on single-cycle control technology and the constant current controller based on conditional technology Anti-windup algorithm, in which the voltage sampling unit is realized by a voltage divider network, and the current sampling unit It is realized by using a Hall current sensor; the constant current controller based on the conditional technology Anti-windup algorithm adopts the conditional technology Anti-windup algorithm to realize feedback control of the sampled output current signal and achieve the purpose of constant current; the described The voltage stabilizing controller based on single-cycle control technology uses single-cycle control technology to perform feedback control on the sampled output voltage signal to achieve the purpose of voltage stabilization; the PWM dimming module can adjust the PWM duty cycle of the output current at the output terminal to achieve a A pulse current PWM dimming; the "AND" logic module uses the constant current controller based on the conditional technology Anti-windup algorithm, the voltage regulator controller based on single-cycle control technology, and the PWM signal output by the PWM dimming module as It inputs a signal and outputs a PWM signal after a logic "AND" operation, and sends this PWM signal to the power switch tube to control the on and off of the power switch tube, so as to realize the energy in the flyback power conversion unit from the primary side to secondary side conversion.

As shown in Figure 2, the main circuit structure consists of a rectifier bridge, a flyback conversion circuit (Flyback), an output rectification filter circuit, and a voltage and current sampling circuit. C ₂ is the input filter capacitor. Resistor R ₁ and diode D ₂ form a simple buffer circuit. Transformer T ₁ and switch tube Q ₁ form a flyback conversion circuit. Let the duty cycle _of switch tube Q1 be , the switching period is T _S , the switch on time is T _on , the off time is T _off , the input current is i ₁ , the transformer turns ratio is N ₁ : N ₂ , the average output voltage is V _o , and the switch tube Q ₁ According to the periodic on-off of PWM, during the T _off = DT _S period when Q ₁ is turned on, the voltage V _S is added to the winding N ₁ after the power supply passes through the bridge rectifier module DG ₁ , the current i ₁ rises linearly, and the magnetic flux of N ₁ increases. The energy storage of the inductor increases, the diode D1 reverses the cut _- off, and the load LED current is controlled by the capacitor Provide; during T _off = (1-D) T _S when Q ₁ is turned off, N ₁ freewheels through the freewheeling diode D ₂ , and at the same time transfers energy to the secondary side winding N ₂ , the secondary side winding current i ₂ And the magnetic flux Φ decreases from the maximum value, D ₁ conducts, thereby converting the magnetic energy of the transformer into electrical energy to supply power to the load. _The voltage divider network composed _of ^R'1 and ^R'2 constitutes _a sampling circuit with an output average voltage V _o , and the potential signal corresponding to the output current I _o can be obtained by sampling the potential _on R _i through the voltage divider network ^R'3 and ^R'4 .

As shown in Figure 3, it is a schematic diagram of a voltage regulator controller based on single-cycle control technology. According to the single-cycle governing equations of the flyback converter:

Comparing u ₁ (t) and u ₂ (t), the duty cycle D can be determined. According to formula (1), the single-cycle control link needs an integral link, as long as u ₁ (t) and u ₂ ( t) to determine the transient duty cycle d and its average value d ^' . u ₁ (t) is a triangular wave, which is obtained by an integrator with a reset switch formed by the error amplifier, u ₂ (t) is obtained by operation of the input signal of the current detection terminal, and then u ₁ (t) and u ₂ ( t) Access the high-speed comparator.

As shown in Figure 4, it is a schematic diagram of a constant current controller based on the anti-windup algorithm of conditional technology.

The output state of the integrator is:

According to formula (2) when the integrator is not saturated, that is, u _n = u _s , the output of the integrator q = k _p e / t , at this time the constant current controller is a common PI controller, and the output current I _o is according to PI The control law follows the given current I _ref ; when the integrator is saturated, u _n > u _s , the output q of the integrator drops, so that the integrator exits saturation and maintains the linear continuity of the output of the constant current controller, so that I _o =I _ref , to improve the dynamic performance of the system and the steady-state accuracy of the output current.

As shown in Figure 4, the PWM signal output by the constant current controller based on the conditional technology Anti-windup control algorithm, the PWM signal output by the voltage regulator controller based on single-cycle control and the PWM signal of the PWM dimmer are "ANDed". The logic module outputs a PWM signal to control the switching off of the switch tube.

Claims (1)

1. a kind of Novel constant-flow voltage stabilizing inverse-excitation type LED drive power, its feature include, exchange input rectifying filter unit, flyback Power conversion unit, output rectification filter unit, voltage/current sampling unit, based on conditioning technology Anti-windup calculate The constant-current controller of method, the voltage-stabilizing controller based on one-cycle control, PWM light-adjusting modules, "AND" logic module；The friendship Flow input rectifying filter unit, flyback sourse converter unit, output rectification filter unit, voltage/current sampling unit composition originally The main circuit part of LED drive power；The constant-current controller based on conditioning technology Anti-windup algorithms, it is based on The voltage-stabilizing controller of one-cycle control, PWM light-adjusting modules, "AND" logic module form the outer of this LED drive power and contained Circuit processed；Electric main is converted to DC pulse voltage and is input to flyback sourse conversion list by exchange input rectifying filter unit Member；The flyback sourse converter unit includes RCD buffer circuits, high frequency transformer, power switch pipe, when power switch pipe turns off When high frequency transformer primary side electrical power storage is got up, it is i.e. defeated to be delivered to secondary side by high frequency transformer for electric energy when switching tube turns on Go out end；The voltage/current sampling unit is responsible for the voltage and current signal of sampled output and respectively by voltage sampling signal Voltage-stabilizing controller based on one-cycle control is sent to current sampling signal and based on conditioning technology Anti- The input of the constant-current controller of windup algorithms, wherein voltage sampling unit are using potential-divider network realization, current sampling unit Realized using Hall current sensor；The constant-current controller based on conditioning technology Anti-windup algorithms, using bar Part working technology Anti-windup algorithms realize feedback control to the output current signal sampled and reach the purpose of constant current； The voltage-stabilizing controller based on one-cycle control is entered using one-cycle control to the output voltage signal sampled Row feedback control reaches voltage stabilizing purpose；The PWM light-adjusting modules can adjust the PWM duty cycle of output end output current, realize A kind of pulse current PWM light modulations；The "AND" logic module, by the constant current based on conditioning technology Anti-windup algorithms Controller, the voltage-stabilizing controller based on one-cycle control, the pwm signal of PWM light-adjusting modules output as its input signal, And a pwm signal after logic "and" operation is exported, and this pwm signal is transported to power switch pipe, control work( The conducting and shut-off of rate switching tube, realize conversion of the energy from primary side to secondary side in flyback sourse converter unit.