The basic knowledge of the LED power supply:
LED power supply from the power source of the traditional lamps and lanterns is completely different, the first LED not by directly using the conventional power grid voltage, in order to satisfy the requirement of the LED special voltage, current, must according to the characteristics of the LED light source design special voltage switching equipment, LED to work properly, different design methods, will only have different performance and conversion efficiency of LED power supply, so only efficient power to make the LED light source stability of fai its biggest advantage, otherwise will not be able to highlight LED energy-saving special. Let us understand the knowledge of the LED power supply in detail.
First of all, the LED power supply according to the drive mode can be divided into two broad categories:
First, constant current drive power supply:
(1) constant current drive circuit of the output current is constant, and the output dc voltage is different with the size of the load resistance within a certain range, load resistance is small, the output voltage is low, the greater the load resistance, the higher the output voltage.
(2)constant current circuit is not afraid of load short circuit, but it is forbidden to load completely open.
(3)LED constant current drive circuit drive is ideal, but the price is relatively high.
(4)maximum current and voltage value should be paid attention to use, it limits the use of the LED quantity;
Second, the voltage type:
(1)When the voltage regulator circuit, to determine the various parameters of the output voltage is fixed, and the output current is as the load increase and decrease and change;
(2) Regulating circuit is not afraid of open load, but it is forbidden to load completely short circuit.
(3)With voltage driving circuit to drive the LED, each string need to add the appropriate resistance can make average a string of LED display brightness;
(4)Brightness will be affected by rectification of voltage change.
Other according to the design of the circuit structure is divided into six categories
(1) resistor, capacitor step-down by capacitance step-down, when used in flashing, as a result of the action of charge and discharge, through the LED current is great, easy to damage the chip. Vulnerable to the impact of power grid voltage fluctuation, low power efficiency and low reliability.
(2) resistance step-down method: through resistance step-down, by the interference of power grid voltage change is bigger, it is not easy to make it regulated power supply, step-down resistance consumes a large part of energy, so this way of electricity power efficiency is very low, and reliable of the system is also lower.
(3) the conventional transformer step-down method: the power of small size, weight, overweight, power efficiency is low, usually only 45% ~ 60%, so general rarely use, reliability is not high.
(4) the electronic transformer step-down method: low power efficiency, voltage range is not wide, general 180 ~ 240 v, moire interference.
(5) the way of RCC step-down switching power supply, voltage range is wide, the power efficiency is higher, generally can be 70% ~ 80%, is widely used. Because of this kind of control mode of the oscillation frequency is discontinuous, switching frequency is not easy to control, load voltage ripple coefficient is big, abnormal load adaptability is poor.
(6)PWM control mode switching power supply : mainly consists of four parts, the input rectifier filter parts, the output rectifier filter, PWM voltage control, switch energy conversion part. The basic working principle of PWM switching voltage stabilizer is changes in input voltage, the parameters of internal and external load, the control circuit by the control signal and reference signal difference of closed loop feedback, adjusting conduction the pulse width of the main circuit switching devices, make the switch power supply output voltage or current stability (i.e., the corresponding regulated power supply and constant current power supply), high power efficiency, generally can be 80% ~ 90%, the output voltage, current stability. Generally this kind of circuit has perfect protection, belongs to the high reliability of power supply.
Buy lights, lamps and lanterns in daily life, the boss might be asked if you need a half drive or all-wheel drive power supply, or whether you need wide voltage. Often half drive is 180 v to 240 v or 80 v to 130 v, according to the actual situation choose the right, you all drive and wide voltage in fact is a meaning, just different theories, is refers to the 80 v ~ 240 v power supply can be used