RGB led based white light control system with quasi-uniform color metric

A feedback control system for controlling a plant operation comprising:

• a controller portion for providing a control signal in response to an error signal, said controller portion having a first response bandwidth and a transfer function C(s) defined as C(s)=Kp+KI/s, wherein Kp and KI, are constant real matrices;
• a plant portion for receiving said control signal and generating an output signal, said plant portion having a second response bandwidth, and a DC gain matrix defined as G, wherein said first response bandwidth is smaller than said second response bandwidth;
• a feedback portion for measuring said desired output signal having a DC gain matrix defined as Q;
• and
• an adder coupled to said feedback portion configured to measure said error signal based on said measured output signal and a desired input signal such that
• Re{(eig((I−GKpQ)−1GKIQ)}<0,
• wherein Re {eig . . . } stands for the real part of the eigen value of the matrix, and I is the identity matrix.

A method in a control system for generating a desired white light by a plurality of Red, Green and Blue light emitting diodes (LEDs) comprising the steps of:

• sensing a white light generated by said plurality of LEDs to measure the color coordinates of said white light, wherein said color coordinates are defined in a first color space;
• transforming said coordinates of said generated white light to a second color space;
• providing reference color coordinates corresponding to said desired white light, wherein said reference color coordinates are expressed in said second color space;
• generating an error color coordinate corresponding to a difference between said desired white light color coordinates and said generated white light color coordinates;
• and
• generating a drive signal for driving said LEDs.