|
YAO Jianjun
WANG Liquan
College of Mechanical and Electrical
Engineering,
Harbin Engineering University,
Harbin 150001, China
JIANG Hongzhou
WU Zhenshun
HAN Junwei
School of
Mechatronics Engineering,
Harbin Institute of Technology,
Harbin 150001, China |
|
|
ADAPTIVE FEED-FORWARD COMPENSATOR FOR
HARMONIC CANCELLATION IN ELECTRO- HYDRAULIC SERVO SYSTEM
Abstract:
Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic distortion of the output signal. The method for harmonic cancellation based on adaptive filter is proposed. The task is accomplished by generating reference signals with frequency that should be eliminated from the output. The reference inputs are weighted by the adaptive filter in such a way that it closely matches the harmonic. The output of the adaptive filter is a harmonic replica and is injected to the fundamental signal such that the output harmonic is cancelled leaving the desired signal alone, and the total harmonic distortion (THD) is greatly reduced. The weights of filter are adjusted online according to the control error by using least-mean-square (LMS) algorithm. Simulation results performed with a hydraulic system demonstrate the efficiency and validity of the proposed adaptive feed-forward compensator (AFC) control scheme.
Key words:
Adaptive filter Adaptive feed-forward compensator Least-mean-square algorithm Dead zone Harmonic distortion |