Digital dimming control method using PID algorithm

Abstract

The invention discloses a digital dimming control method using a PID algorithm. The method comprises a first step of initializing a program, and setting an initial setting value (power constant value) and an upper limit and a lower limit of a target value, wherein the upper limit and the lower limit are respectively X and Y; a second step of receiving an external constant power sampling value Next_Point, and calculating a current difference ek_0 between a setting value MB and the sampling value, that is, ek_0=MB-Next_Point; a third step of calculating a target value increment so as to obtain an amount of increase or decrease Udk of a target value, adjusting the target value according to the PID algorithm so as to obtain a target value Uk after PID adjustment; a fourth step of exchanging the setting value and a sampling difference; and a fifth step of comparing the target value with a set threshold, and finally returning the target value undergone PID adjustment to a master program to change an output frequency. The method has the beneficial effects that output frequency adjustment is changed and the power is stabilized by using a PID algorithm formula; if a feedback voltage is high, the output frequency is increased, if the feedback voltage is low, the output frequency is decreased; and the power is output steadily through sampling and high-speed cycling of PID calculation.

Description

technical field [0001] The invention relates to the field of digital dimming, in particular to a digital dimming control method using a PID algorithm. Background technique [0002] In a circuit for controlling a light-emitting device (such as a gas discharge lamp, HID), it is often necessary to provide a dimming function. There are mainly two types of dimming methods in the prior art, one is analog dimming, which faces a very serious problem of output current accuracy. Almost every HID driver uses some kind of series resistor to discern the current flow. The current discrimination voltage (VSNS) is selected by compromising low power loss and high signal-to-noise ratio. Tolerances, offsets and delays in the drive result in a relatively constant error. To reduce the output current in a closed-loop system, VSNS must be reduced. This in turn degrades the accuracy of the output current, and ultimately, the output current cannot be specified, controlled, or guaranteed. [000...

AI Technical Summary

Problems solved by technology

However, there are still problems such as power instability in practical applications, and the overshoot of the driving current will also have a certain impact on the life of the HID chip.

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