Output current adjustable and controllable LED driver and driving method

The invention discloses an output current adjustable and controllable LED (Light-emitting Diode) driver and a driving method. The driver comprises an EMI (Electro-Magnetic Interference) rectifier bridge circuit, an energy storage inductor, an isolated unit, an energy storage capacitor, a power grid quality control unit, an energy coupling unit, a first electronic switch, a second electronic switch, a power control unit, an output current control unit, an intelligent control unit, a first voltage sampling circuit, a second voltage sampling circuit, a third voltage sampling circuit, a first current sampling unit, a second current sampling unit, a third current sampling unit, a fourth current sampling unit and a fifth current sampling unit. The driver can perform closed-loop control and adjustment on current output to an LED load according to a nonlinear relationship of the V-I (Voltage-Current) characteristic of the LED load, optimizes power output to the LED load, is high in driving efficiency, long in service