LED power terminologywhat is a led driver power supplyTime:2021-03-23 / Read:131
LED drive power supply is the power supply conversion into a specific voltage and current to drive LED light power converter, usually: LED drive power input includes high voltage AC (i.e., power supply), low voltage DC, high voltage DC, low voltage and high frequency AC (such as the output of electronic transformer).
When youchoosing and design the LED drive power supply, we often see that some LED drive power products have many professional terms， These are some of the things we need to consider:
Isolation and non-isolation: At present, in the general LED drive power supply market, there is a distinction between non-isolated design and isolated drive power. The non-isolated design is limited to double-insulated products, such as replacement products for light bulbs, where the LED and the entire product are integrated and sealed in non-conductive plastic, so the end user does not have any risk of electric shock. Secondary products are isolated and relatively expensive, but where users can access the LED and output wiring (usually in the case of LED lighting and street lighting applications), this product is indispensable. The LED drive power supply with isolation transformer or electrical isolation means that the LED can be directly touched by hand without electric shock. Although the LED drive power supply without an isolation transformer can still achieve partial mechanical insulation with the help of a protective casing, the LED at this time cannot be directly contacted during operation. Therefore, the safety factor of isolation relative to non-isolation has improved a lot.
The problem of constant current accuracy of the primary side: The production accuracy of the transformation is difficult to control, resulting in a large output current drift when the primary side solution uses a low-quality transformer. Therefore, the primary side solution has been improved to increase the secondary side constant current control circuit, which is more complicated than the ordinary primary side solution, but compared with the flyback solution, the optocoupler can still be omitted, and the system has the highest cost performance. The primary side solution is to control the output power and current completely on the AC primary side, the most accurate can achieve 5% constant current accuracy, and the secondary side only needs a simple output circuit. The primary side mainly relies on the feedback of the auxiliary side to control the output voltage, relies on the current limiting resistor to control the primary side current, and at the same time multiplies the turns ratio to control the accuracy of the output current. The original-side solution inherits the various advantages of the isolated flyback circuit, while the structure is simple, and it can achieve small size and low cost. It has become the mainstream driver at present.
Resistance-capacitance step-down: Use the impedance of the capacitor under AC to limit the input current, so as to obtain a DC level to power the LED. This driving mode has a simple structure and low cost, but the input is non-isolated, which has potential safety hazards. Moreover, the conversion efficiency is very low, and constant current control cannot be achieved.
High power factor: Power factor is the requirement of the power grid on the load. Generally, there are no mandatory indicators for electrical appliances below 70 watts. Although the power factor of a single electrical appliance with low power is lower, it has little effect on the power grid, but if everyone lights up at night, if the load of the same kind is too concentrated, it will cause serious pollution to the power grid. For LED driving power supplies of 30 watts to 40 watts, there may be certain index requirements for power factors.
High efficiency: LED is an energy-saving product, and the efficiency of the drive power supply should be high. It is especially important for the structure where the power supply is installed in the luminaire. Because the luminous efficiency of the LED decreases as the temperature of the LED increases, the heat dissipation of the LED is very important. The efficiency of the power supply is high, and its power consumption is small.
Surge protection: The ability of LEDs to resist surges is relatively poor, especially the ability to resist reverse voltage. It is also important to strengthen protection in this area. Some LED lights are installed outdoors, such as LED street lights. Due to the initiation of the grid load and the induction of lightning strikes, various surges will invade from the grid system, and some surges will cause damage to the LED. Therefore, the LED drive power supply must have the ability to suppress the intrusion of surges and protect the LED from damage.
Protection method: The protection mainly refers to the external power supply, such as the LED waterproof power supply. This power supply can meet the requirements of waterproof and moisture-proof. If the outdoor street lamp and cast light lamp shell is used, it must be also light-resistant.
Line regulation: It changes linearly within the specified range of the percentage of the input voltage to the output voltage.
Load regulation: the rate of change of the output current when the load changes within a predetermined range.
Ripple noise: refers to the output voltage of the DC power supply. It is not particularly smooth and unstable voltage output, as noise ripples.
Overvoltage protection: refers to a protection method that disconnects the power supply or reduces the voltage of the controlled equipment when the voltage of the protected line exceeds a predetermined maximum value.
Over-temperature protection: When the temperature of the power supply exceeds the maximum temperature it can withstand during the use of the power supply, the power supply will automatically stop working. In order to avoid damage to the motherboard components, the power supply will automatically start working after the temperature of the power supply drops , Or restart manually.
Short-circuit protection: protection for short-circuit faults caused by electrical short-circuiting of conductors of unequal potential in the power supply system.