Active Noise Absorption Method and Device with Resonance Frequency Tracking

Abstract

This invention provides a noise absorption method and device with an adjustable conical shaped annular aperture on a Helmholtz resonator composed of a Helmholtz resonant cavity, a resonance control package, a sensing & actuating modules and a controller. The resonant cavity harvests noise energy by tracking of the noise resonance frequency which is achieved by adjusting the aperture openness between a movable conical shell and the resonant cavity according to a resonance control algorithm of combination of FFT (Fourier Fast Transform) adjustment and PLL (Phase-Locked Loop control) adjustment.

Meanwhile, the controller applies a driving current into a coil attached to the movable conical shell based on DXHS (Delayed-X Harmonic Synthesizer) algorithm, so that harvested noise energy on the movable conical shell can be absorbed with maximum efficiency. Additionally, a part of the noise energy is dissipated by resonant air friction flowing through the annular aperture on the cavity.

Claims

1. An active noise absorption method and device, comprising: a Helmholtz resonator (resonant cavity) with an adjustable conical shaped annular aperture used for harvesting noise energy; a resonance control package including a movable conical shell with coil and two magnetic poles served as an actuator for tracking dominant frequency of noise source and absorbing converted vibrational energy taken by the movable conical shell; a sensing & actuating modules used to amplify, filter sensing signals, and to drive a driving coil which current is measured; a group of sensors including two acoustic sensors positioned outside and inside of the resonator, an accelerometer of the movable conical shell and a current sensor of the driving coil; and a controller configured to acquire the sensor signals and calculate output in real time in accordance with control algorithm to ensure resonance is tracked and harvested energy is absorbed efficiently by applying a required current to the driving coil.

2. An algorithm of resonance control for tracking of absorbed noise dominant frequency is performed by adjusting opening gap of a conical annular aperture between the resonant cavity and the movable conical shell by means of adjustment of manual screw nuts for selection of operating frequency band and adaptively combined adjustment of FFT (Fourier Fast Transform) coarse adjustment and PLL (Phase-Locked Loop) fine adjustment.

3. An algorithm of absorbing control is used to maximize absorption of vibrational energy on the movable conical shell produced by the resonance by means of controlling vibrational velocity vector of the movable conical shell to match with velocity vector of ideal control target using DXHS (Delayed-X Harmonic Synthesizer) algorithm which controls electromagnetic force to absorb a balance energy flow on the movable conical shell coming from the resonant air.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0132] The foregoing and/or other objects features, and advantages of the invention will become more apparent from the following description of a preferred embodiment with reference to the accompany drawings in which like reference numerals designate like elements and wherein:

[0133] FIG. 1A is a vertical cross-sectional view of the absorber according to embodiment of the invention, taken along line 1-1 of FIG. 1B;

[0134] FIG. 1B is a top plane view of the FIG. 1A;

[0135] FIG. 1C is a transverse cross-sectional view, taken along line 3-3 of the FIG. 1A;

[0136] FIG. 2 is a control block diagram illustrating architecture of the active noise absorption method and device with resonance frequency tracking;

[0137] FIG. 3 is a block diagram of electro-mechanical model of the movable conical shell.

REFERENCE MARKS IN THE DRAWINGS

[0138] 10 Top Cover [0139] 11 Cylindrical Housing [0140] 12 Bottom Cover [0141] 13 Resonant Cavity [0142] 20 Upper Magnetic Pole [0143] 21 Magnet [0144] 22 Lower Magnetic Pole [0145] 23 Fastener for Magnetic Components [0146] 25 Through Holes of the Lower Magnetic Pole [0147] 30 Trilobal Metal Springs [0148] 31 Fastener for Outer Ends of the Trilobal Metal Springs [0149] 32 Upper Screw Nuts of the Fastener for the Outer Ends [0150] 33 Lower Screw Nuts of the Fastener for the Outer Ends [0151] 34 Bracket of Conical shaped Shell [0152] 36 Fastener for the Bracket of Conical Shell [0153] 37 Driving Coil Winding on Inner Wall of the Bracket of Conical Shell [0154] 40 Conical Angle of Conical Shaped Annular Aperture [0155] 41 Opening Gap of Conical Shaped Annular Aperture [0156] 42 Diameter of Upper Conical Aperture of the CavityD.sub.0 [0157] 50 Acoustic Sensor Outside of the Resonant Cavity [0158] 51 Acoustic Sensor Inside of the Resonant Cavity [0159] 52 Accelerometer attached into the Bracket of Conical Shaped Shell [0160] 53 Current Sensor of the Driving Coil [0161] 60 Mechanical Schematic of the absorber [0162] 100 Controller of the Method and Device [0163] 101 Voltage Control Signal for the Driving Coil [0164] 102 Generator of PWM/PDM for Bridge Driving [0165] 110 Sensing Module [0166] 120 Actuating Module [0167] 130 Absorbing Control Unit [0168] 131 Parameters of Ideal Control Target of the Movable Conical Shell [0169] 132 Signal Integral [0170] 133 Generator of Target Signal [0171] 134 Signal Combiner [0172] 135 Update Module of DXHS algorithm [0173] 136 FFT calculation Module of .sub.in [0174] 137 Initial Parameters Module [0175] 140 Resonance Control Unit [0176] 141 FFT calculation Module of .sub.ex [0177] 142 Look-up Table for .sub.ox.sub.o [0178] 143 Signal Combiner [0179] 144 Electro-kinetic Coefficient [0180] 145 Resistance of the Driving Coil [0181] 150 Phase-Locked Loop [0182] 151 Normalized Module [0183] 152 /2 Phase Shift Module [0184] 153 Normalized Module [0185] 154 Signal Product [0186] 155 Lowpass Filter Module [0187] 156 Look-up Table for u.sub.dx.sub.o [0188] 160 Calibration Unit of the Control Parameters [0189] 161 Driving Coil Current Capture Module [0190] 162 Calibration Module for the Control Parameters [0191] 200 Electric-kinetic Model of the Movable Conical Shell [0192] 201 Acoustic Signal Outside of the Resonant Cavity [0193] 202 Acoustic Signal Inside of the Resonant Cavity [0194] 203 Acceleration Signal of the Movable Conical Shell [0195] 204 Voltage Signal for the Driving Coil [0196] 205 Current Signal for the Driving Coil [0197] 211 Lowpass Filter Module for Measurement Current [0198] 212 Electro-kinetic Coefficient for x.sub.0 [0199] 213 Aerodynamic Transfer Function of the Movable Conical Shell [0200] 214 Signal Combiner [0201] 215 Velocity Transfer Function of the Movable Conical Shell [0202] 216 Differential Module [0203] 217 Potential inducing Coefficient [0204] 218 Signal Combiner [0205] 231 Lowpass Filter Module for Measurement Current [0206] 232 Resistance of the Driving Coil [0207] 233 Signal Combiner [0208] 234 High-pass Filter Module for Measurement Current [0209] 235 First-order Proportional Differential Module [0210] 236 Electro-kinetic Coefficient