How to confirm the reliability of LED power supply
1. Several indicator forms describing the impact of input voltage on output voltage
(1) Voltage stabilization coefficient
① Absolute voltage stabilization coefficient K
When the load remains constant, the ratio of the output DC voltage change △ Uo of the regulated power supply to the input grid voltage change △ Ui, i.e. K=△ Uo/△ Ui.
② Relative voltage stabilization coefficient S
When the load remains constant, the ratio of the relative change △ Uo/Uo of the output DC voltage Uo of the regulator to the relative change △ Ui/Ui of the input grid voltage Ui is denoted as S=△ Uo/Uo/△ Ui/Ui.
(2) Grid adjustment rate
When the input grid voltage changes by+/-10% from the rated value, the relative change in the output voltage of the regulated power supply is sometimes expressed in absolute value.
(3) Voltage stability
The voltage stability of a voltage regulator is defined as the relative change in output voltage △ Uo/Uo (percentage) caused by the variation of input voltage within the specified range while maintaining the load current at any value within the rated range.
2. Several indicator forms of the influence of load on output voltage
(1) Load regulation rate (also known as current regulation rate)
The maximum relative change in output voltage when the load current changes from zero to its maximum value at the rated grid voltage, commonly expressed as a percentage and sometimes as an absolute change.
(2) Output resistance (also known as equivalent internal resistance or internal resistance)
At rated grid voltage, if the output voltage changes △ Uo due to the load current variation △ IL, the output resistance is Ro=| △ Uo/△ IL | Ω.
3. Several indicator forms of ripple voltage
(1) Maximum Ripple Voltage
The absolute value of output voltage ripple (including noise) at rated output voltage and load current is usually expressed as peak or effective value.
(2) Ripple factor Y (%)
At rated load current, the ratio of the effective value Urms of the output ripple voltage to the output DC voltage Uo is Y=Umrs/Uox100%.
(3) Ripple voltage suppression ratio
At the specified ripple frequency (e.g. 50HZ), the ratio of the ripple voltage Ui~in the input voltage to the ripple voltage Uo~in the output voltage, that is, the ripple voltage suppression ratio=Ui~/Uo~.
