Multi-channel LED current equalization drive circuit

Abstract

The invention discloses a multi-channel LED current equalization drive circuit. The traditional drive circuit is complicated and has high cost. In the invention, a positive input end of a high-frequency AC voltage pulse generating circuit is connected with a positive end of an external DC input power supply, a negative input end of the high-frequency AC voltage pulse generating circuit is connected with a negative end of the external DC input power supply, one output end of the high-frequency AC voltage pulse generating circuit is connected with one end of an inductor Lr, the other end of theinductor Lr is connected with one end of a capacitor Cr, and the other end of the capacitor Cr is respectively connected with a positive input end of a forward rectifying circuit and a negative inputend of a backward rectifying circuit; and the other output end of the high-frequency AC voltage pulse generating circuit is connected with a negative input end of the forward rectifying circuit and apositive input end of the backward rectifying circuit. The currents of two parallel subcircuits are equalized by the charge and discharge equalization of the capacitor, and the number of LEDs with equalized currents can be increased by one time under the condition of same output voltage.

Description

technical field [0001] The invention belongs to the technical field of switching power supplies and relates to an LED driving circuit. Specifically, it is a drive circuit that utilizes the principle of capacitor charge-discharge balance and current transformers to realize load current balance of even-numbered LEDs. Background technique [0002] LEDs need to be driven by constant current. In some high-power lighting applications, LEDs usually need to be used in series or in parallel. When LEDs are used in parallel, each channel needs constant current control, which increases the circuit cost. Therefore, for LEDs, direct series connection is the easiest way, but if too many LEDs are connected in series, on the one hand, the output voltage of the driver will be higher, which increases the cost of circuit components; on the other hand, if one of the LEDs fails, the entire string will The LED light fails, so it's not very reliable from a system point of view. [0003] figure ...

AI Technical Summary

Problems solved by technology

Although this technology is feasible in principle, there are some shortcomings in practical application, which affect its practical application, such as: (1) The discreteness of transformer excitation inductance will affect the current sharing degree of multiple output currents

(2) When a certain load is short-circuited, since only the capacitor is filtered, the corresponding transformer of this road is equivalent to a short-circuit, resulting in a change in the total excitation inductance connected in series on the primary side, thereby affecting the steady-state gain of the converter and increasing the Difficult to control, thus seriously reducing the reliability of the converter

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