CN115727016A - Electronic system with heat dissipation and feedforward active noise control function - Google Patents

Abstract

An electronic system with heat dissipation and feedforward active noise control functions comprises a fan module, an embedded controller, an error microphone, an active noise reduction controller and a loudspeaker module. The error microphone captures noise and outputs a corresponding error signal when the electronic system is in operation. The active noise reduction controller calculates narrow-band noise related to actual single-blade fundamental frequency noise or actual BPF fundamental frequency noise in noise generated by the fan module in actual operation according to the error signal and fan information provided by the embedded controller, and then drives the loudspeaker module in sequence to provide an opposite-phase noise signal. The value of the error signal is adjusted to 0 by adaptively adjusting the reverse noise signal to offset the noise generated when the electronic system operates, thereby providing the functions of heat dissipation and noise reduction.

Description

Electronic system with heat dissipation and feedforward active noise control function

Technical Field

The invention provides an electronic system with heat dissipation and feedforward active noise control functions, and particularly relates to an electronic system with heat dissipation and feedforward active narrow-band noise control functions.

Background

In modern information society, computer systems have become an indispensable information tool for most people. In order to prevent the components from being overheated and thus causing power reduction or damage, a fan is generally used in a computer system to provide a heat dissipation function for exhausting heat generated inside the computer system or sucking cold air outside the computer system.

The rotating speed and the static pressure of the fan determine the air flow of the fan, the noise generated when the fan operates is approximately proportional to the quintic root of the rotating speed, and the higher the rotating speed is, the stronger the heat dissipation capacity is, but the larger the noise is. As the function of the cpu becomes stronger, the waste heat generated inside the device increases, and the trend of miniaturization reduces the heat flow efficiency, so that it is an important issue how to achieve both heat dissipation and noise reduction.

Disclosure of Invention

The invention provides an electronic system with heat dissipation and feedforward active noise control functions, which comprises a fan module, an embedded controller, an error microphone, an active noise reduction controller and a loudspeaker module. The fan module operates according to a fan control signal to provide a heat dissipation function. The embedded controller is used for providing the fan control signal and a synchronous signal, wherein the synchronous signal comprises information of the structure and the operation setting of the fan module. The error microphone is used for detecting noise generated when the electronic system operates so as to provide a corresponding error signal. The active noise reduction controller is used for solving an actual single-blade fundamental frequency and an actual blade passing frequency fundamental frequency when the fan module runs according to the synchronous signal and the error signal, and generating a loudspeaker control signal according to the actual single-blade frequency point and the actual blade passing frequency fundamental frequency. The loudspeaker module is used for generating an inverse noise signal according to the loudspeaker control signal, wherein the inverse noise signal at least comprises a first noise elimination waveform and a second noise elimination waveform, the first noise elimination waveform is an inverse signal related to the actual single-blade fundamental frequency, and the second noise elimination waveform is an inverse signal related to the actual blade passing frequency fundamental frequency.

Drawings

Fig. 1 is a functional block diagram of an electronic system with heat dissipation and feedforward active noise control according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of an implementation of an active noise reduction controller according to an embodiment of the present invention.

FIG. 3 is a flow chart illustrating operation of an electronic system according to an embodiment of the present invention.

Wherein the reference numerals are as follows:

10: processor with a memory having a plurality of memory cells

20: fan module

30: embedded controller

40: loudspeaker module

50: error microphone

60: active noise reduction controller

62: frequency calculator

64: signal generator

66: digital filter

68: loudspeaker drive circuit

70: secondary path compensation transfer function module

72: secondary path transfer function module

74: noise weighting and conversion module

76: adaptive filter

100: electronic system

310-350: step (ii) of

S _FG : fan control signal

S _MIC : loudspeaker control signal

S _SYN : synchronization signal

y (n): noise signal of opposite phase

y' (n): correcting an inverted noise signal

e (n): error signal

e' (n): post-processing error signal

d (n): noise signal

Detailed Description

Fig. 1 is a functional block diagram of an electronic system 100 with heat dissipation and feedforward active noise control according to an embodiment of the invention. The electronic system 100 includes a processor 10, a fan module 20, an Embedded Controller (EC) 30, a speaker module 40, an error microphone 50, and an Active Noise Cancellation (ANC) controller 60.

The processor 10 may be a Central Processing Unit (CPU) or a Graphics Processing Unit (GPU), which is a key operation engine in the electronic system 100, responsible for executing instructions and programs required by the operating system, and is also a main source of waste heat in the electronic system 100.

The fan module 20 may have different structures according to its types, and mainly utilizes a motor to drive the blades to rotate, so as to bring the cooler air into the inside of the case, and discharge the hotter air inside, thereby achieving the heat dissipation effect. In the present invention, the fan module 20 is configured to provide a fan control signal S according to the embedded controller 30 _FG To operate, fan control signal S _FG The larger the value of (b), the faster the motor speed in the fan module 20, the stronger the heat dissipation effect, but also the larger the noise. Fan module 20 will typically be the primary source of noise during operation of electronic system 100. In one embodiment, the fan control signal S _FG The square wave signal may be a Pulse Width Modulation (PWM) square wave signal, and the duty cycle is changed to adjust the rotation speed of the motor in the fan module 20. In one embodiment, fan module 20 may include one or more axial fans or centrifugal fans. However, the number of fans, the type of fans, and the driving manner of the fans included in the fan module 20 are not intended to limit the scope of the present invention.

The embedded controller 30 stores the EC codes for the various operations of the associated electronic system 100 and the timing of the important signals at power-on. In the power-off state, the embedded controller 30 will always keep running to wait for the power-on information of the user; in the power-on state, the embedded controller 30 controls the standby/sleep state of the system, the keyboard controller, the charging indicator, and the rotation speed of the motor in the fan module 20. The embedded controller 30 typically includes a temperature sensor (not shown in FIG. 1) to monitor the operating temperature of the processor 10 and output a fan control signal S accordingly _FG . The higher the operating temperature of the processor 10, the higher the fan control signal S _FG The greater the duty cycle of (c), the faster the motor speed in the fan module 20; the lower the operating temperature of the processor 10, the lower the fan control signal S _FG The smaller the duty cycle and the slower the motor speed in the fan module 20.

The speaker module 40 is an electronic component that converts an electronic signal into an acoustic signal, and generally includes a diaphragm (diaphragm) and a driving circuit including an electromagnet and a voice coil. The speaker module 40 may provide a speaker control signal S according to the ANC controller 60 _MIC To operate when the loudspeaker control signal S _MIC When the current passes through the voice coil, the voice coil vibrates along with the frequency of the current, and the vibrating diaphragm connected with the voice coil naturally vibrates, so that the surrounding air is pushed to vibrate to generate sound. In the embodiment of the present invention, the diaphragm of the speaker module 40 is disposed in the air outlet structure of the fan module 20, and can be controlled according to the speaker control signal S _MIC To generate an inverted noise signal y (n).

The error microphone 50 is used for capturing noise during operation of the electronic system 100 and outputting a corresponding error signal e (n) to the ANC controller 60, wherein d (n) represents a noise signal to be eliminated during operation of the electronic system 100. Since fan module 20 is the main noise source, error microphone 50 may be located near the outlet of fan module 20. The error microphone 50 may detect noise through a primary path and a secondary path: the main path is related to the signal transmission path between the fan module 20 and the error microphone 50, and the noise signal d (n) is captured through the main path; the secondary path is associated with the signal transmission path between the speaker module 40 and the error microphone 20, and a corrected inverse noise signal y' (n) of the associated inverse noise signal y (n) is extracted through the secondary path. In more detail, the error signal e (n) output by the error microphone 50 is the difference between the noise signal d (n) and the corrected inverse noise signal y' (n), and a smaller value of the error signal e (n) represents a better noise reduction effect. In one embodiment, the error microphone 50 may be a digital Micro Electro Mechanical System (MEMS) microphone with high thermal resistance, high vibration resistance, and high radio frequency interference resistance. However, the type of error microphone 50 does not limit the scope of the present invention.

ANC controller 60 may receive a synchronization signal S from embedded controller 30 _SYN And an error signal e (n) from the error microphone 50, wherein the synchronization signal S _SYN IncludedInformation regarding the configuration (e.g., number of fan blades) and operational settings (e.g., motor speed in different modes) of the fan module 20. According to the synchronization signal S _SYN And an error signal e (n), the ANC controller 60 can calculate the narrow band noise in the noise generated by the fan module 20 during the actual operation, and then provide the speaker control signal S _MIC So as to drive the speaker module 40, the inverted noise signal y (n) provided by the speaker module 40 can effectively cancel the noise signal d (n), i.e. the error signal e (n) is reduced to 0 as much as possible.

Fig. 2 is a schematic diagram of an implementation of the ANC controller 60 according to an embodiment of the present invention. ANC controller 60 includes a frequency calculator 62, a signal generator 64, a digital filter 66, a speaker driver circuit 68, a secondary path compensation transfer function module 70, a secondary path transfer function module 72, a noise weighting and conversion module 74, and an adaptive filter 76.

FIG. 3 is a flowchart illustrating the operation of the electronic system 100 according to the present invention, which includes the following steps:

step 310: the error microphone 50 captures the noise and provides a corresponding error signal e (n).

Step 320: synchronization signal S provided by ANC controller 60 from embedded controller 30 _SYN The number of fan blades in the fan module 20 and the motor speed in each mode are obtained, and the corresponding reference signal x (n) is calculated.

Step 330: ANC controller 60 determines the actual single-blade fundamental frequency, actual frequency multiplication, and actual BPF of fan module 20 during operation based on error signal e (n) and reference signal x (n), and provides speaker control signal S accordingly _MIC 。

Step 340: the speaker module 40 controls the signal S according to the speaker _MIC An inverted noise signal y (n) is generated.

Step 350: ANC controller 60 provides a corrected reference signal x '(n) for secondary path corrected reference signal x (n), and corrects inverted noise signal y (n) to provide a corrected inverted noise signal y' (n); step 310 is performed.

In step 310, the error microphone 50 captures noise and provides a corresponding error signal e (n) when the electronic system 100 is in operation. As previously discussed, the error signal e (n) provided by the error microphone 50 is the difference between the noise signal d (n) and the corrected inverted noise signal y' (n), and the noise signal d (n) is primarily derived from the rotation of the fan blades when the fan module 20 is operating.

The noise source of fan module 20 during operation is from the airflow caused by the rotation of the motor, wherein the narrow frequency component may be derived from the thickness noise caused by the volume displacement generated by the motion of the fan blades, or the Blade Passing Frequency (BPF) noise caused by the variable load force of the fan blade surface (axial lift force and pull force of the fan surface). Since the BPF and associated harmonics are related to the pressure disturbances generated as each fan blade passes a fixed reference point, certain narrow frequency noise is generated when the blade tip generates periodic pressure waves. Therefore, in step 320, the frequency calculator 62 of the ANC controller 60 may calculate the frequency according to the synchronization signal S provided by the embedded controller 30 _SYN The motor speed, the single-blade frequency point and the blade number of the fan module 20 are known, wherein the BPF is the product of the motor speed and the blade number of the fan module 20. Assuming that the number of blades of the fan module 20 is 37, the following table shows the data calculated by the frequency calculator 62, but does not limit the scope of the present invention. The motor speed is in units of rpm and the frequency is in hertz.

Motor speed	Fundamental frequency	Frequency doubling	Frequency tripling	Quadruple frequency	Number of blades	BPF	BPFx2	BPFx3
									500	8.3	16.6	24.9	33.2	37	307.1	614.2	921.3
1000	16.6	33.2	49.8	66.4	37	614.2	1228.4	1842.6
									1500	25	50	75	100	37	925	1850	2775
2000	33.3	66.6	99.9	133.2	37	1232.1	2464.2	3696.3
									2500	41.7	83.4	125.1	166.8	37	1542.9	3085.8	4628.7
3000	50	100	150	200	37	1850	3700	5550
									3500	58.3	116.6	174.9	233.2	37	2157.1	4314.2	6471.3
4000	66.7	133.4	200.1	266.8	37	2467.9	4935.8	7403.7
									4500	75	150	225	300	37	2775	5550	8325
5000	83.3	166.6	249.9	333.2	37	3082.1	6164.2	9246.3
									5500	91.6	183.2	274.8	366.4	37	3389.2	6778.4	10167.6
5700	95	190	285	380	37	3515	7030	10545

Watch 1

Next, the signal generator 64 of the ANC controller 60 generates a reference signal x (n) according to the data calculated by the frequency calculator 62, wherein the reference signal x (n) includes information such as an estimated frequency multiplication of the fan module 20, an estimated BPF, and a sound pressure spectrum (dBSPL) at different motor speeds, so as to determine a reference power value of the speaker control signal smc, and the power value of the speaker control signal smc can be changed by adjusting the parameter W (Z) of the digital filter 66.

In steps 330 and 340, digital filter 66 of ANC controller 60 drives speaker driver circuit 68 to output speaker control signal smc according to error signal e (n) and reference signal x (n), and thus drives speaker module 40 to provide inverse noise signal y (n), where W (Z) represents an adjustable operating parameter of digital filter 66.

White noise (white noise) transmitted to the fan module 20 during operation and the characteristics of the speaker module 40 itself affect the secondary path between the speaker module 40 and the error microphone 50, assuming that the reverse-phase noise signal y (n) currently provided by the speaker module 40 can completely cancel the noise signal d (n), but after being transmitted through the secondary path, the reverse-phase noise signal y (n) captured by the error microphone 50 may not completely cancel the noise signal d (n) due to signal attenuation or distortion. Therefore, in step 350, the secondary path compensation transfer function module 70 of the ANC controller 60 can obtain the estimated signal S ^ (Z) of the secondary path from the embedded controller 30, and then correct the reference signal x (n) according to the estimated signal S ^ (Z) to provide the corrected reference signal x' (n). The secondary path transfer function block 72 of ANC controller 60 may be a spectrum analyzer that measures the actual frequency response S (Z) of the secondary path and corrects the inverse noise signal y (n) accordingly to provide a corrected inverse noise signal y' (n) to compensate for the effect of the secondary path on signal transmission.

The noise weighting and converting module 74 is coupled to the error microphone 50, and can process the error signal e (n) measured by the error microphone 50 according to a specific signal weighting method and a specific signal converting method, and then transmit the processed error signal e' (n) to the adaptive filter 76. In one embodiment, the noise weight conversion module 74 may process the error signal e (n) using an a-weight (a weighting) and a Fast Fourier Transform (FFT). However, the signal weighting method and the signal transformation method used by the noise weighting transformation module 74 are not limited to the scope of the present invention.

The adaptive filter 76, coupled to the secondary path compensation transfer function module 70 and the noise weighting transformation module 74, processes the corrected reference signal x '(n) and the processed error signal e' (n) according to a specific algorithm, thereby adjusting the parameter W (Z) of the digital filter 66. More specifically, the corrected reference signal x '(n) includes information of the motor speed, the estimated single-blade fundamental frequency, the estimated frequency multiplication, the estimated BPF, and the like of the fan module 20, and the adaptive filter 76 can obtain information of the related narrow-band noise, such as the actual single-blade fundamental frequency, the actual frequency multiplication, the actual BPF, and the like during the operation of the fan module 20 according to the processed error signal e' (n), and further adjust the parameter W (Z) of the digital filter 66 accordingly. As such, when the digital filter 66 drives the speaker driving circuit 68 to output the speaker control signal SMIC, the inverted noise signal y (n) generated by the speaker module 40 reflects the actual operating condition of the fan module 20 and the current noise reduction level. More specifically, the inverted noise signal y (n) comprises a first noise cancellation waveform and a second noise cancellation waveform, wherein the first noise cancellation waveform is an inverted signal related to the actual single-blade fundamental frequency, and the second noise cancellation waveform is an inverted signal related to the actual BPF fundamental frequency.

In one embodiment, the adaptive filter 76 may process the corrected reference signal x '(n) and the processed error signal e' (n) according to a Least Mean Square (LMS) algorithm. However, the algorithm used by the adaptive filter 76 is not limiting to the scope of the present invention.

In summary, in the electronic system 100 of the present invention, the error microphone 50 captures noise and outputs a corresponding error signal, and the ANC controller 60 calculates a narrow-band noise (an actual single-blade fundamental frequency noise or an actual BPF fundamental frequency noise) in the noise generated by the fan module 20 during actual operation according to the error signal and the fan information provided by the embedded controller 30, and then drives the speaker module 40 to provide an inverse-phase noise signal y (n), so that the inverse-phase noise signal y (n) can cancel the noise generated during operation of the electronic system 100. By adaptively adjusting the inverse noise signal to adjust the value of the error signal to 0, the present invention can achieve both heat dissipation and noise reduction.

The above-mentioned embodiments are merely preferred embodiments of the present invention, and all equivalent changes and modifications made by the claims of the present invention should be covered by the scope of the present invention.

Claims (10)

1. An electronic system with heat dissipation and feedforward active noise control functions, comprising:

the fan module is used for operating according to a fan control signal to provide a heat dissipation function;

an embedded controller for providing the fan control signal and a synchronization signal, wherein the synchronization signal comprises information of the structure and operation setting of the fan module;

an error microphone for detecting the noise generated by the electronic system during operation to provide a corresponding error signal;

an active noise reduction controller for:

calculating an actual single-blade fundamental frequency and an actual blade passing frequency fundamental frequency when the fan module runs according to the synchronous signal and the error signal; and

generating a loudspeaker control signal according to the actual single-blade frequency point and the actual blade passing frequency fundamental frequency; and

a speaker module for generating an inverse noise signal according to the speaker control signal, wherein the inverse noise signal at least comprises a first noise cancellation waveform and a second noise cancellation waveform, the first noise cancellation waveform is an inverse signal related to the actual single-blade fundamental frequency, and the second noise cancellation waveform is an inverse signal related to the actual blade passing frequency fundamental frequency.

2. The electronic system of claim 1, wherein the active noise reduction controller comprises:

a frequency calculator for calculating an estimated single-blade fundamental frequency, an estimated single-blade frequency multiplication and an estimated blade passing frequency fundamental frequency of the fan module according to the synchronous signal;

a signal generator for generating a reference signal according to the estimated single-blade fundamental frequency, the estimated single-blade frequency multiplication and the estimated blade passing frequency fundamental frequency; and

a digital filter for performing operation on the reference signal to determine a reference power value of the speaker control signal.

3. The electronic system of claim 2, wherein the active noise reduction controller further comprises:

an adaptive filter for adjusting the parameters used by the digital filter in performing the operation according to the reference signal and the error signal, thereby adaptively adjusting the power value of the speaker control signal.

4. The electronic system of claim 3, wherein:

the adaptive filter uses a least mean square algorithm to process the reference signal and the error signal.

5. The electronic system of claim 3, wherein the active noise reduction controller further comprises:

a secondary path compensation transfer function module, coupled to the embedded controller, for receiving an estimated signal of a secondary path, and correcting the reference signal according to the estimated signal of the secondary path to provide a corrected reference signal; and

a noise weighting and converting module for processing the error signal according to a specific signal weighting method and a specific signal converting method to provide a processed error signal, wherein:

the secondary path is associated with a signal transfer path between the speaker module and the error microphone; and is provided with

The adaptive filter adjusts parameters used by the digital filter in performing operations according to the corrected reference signal and the processed error signal.

6. The electronic system of claim 5, wherein the active noise reduction controller further comprises:

a secondary path transfer function module for measuring the actual frequency response of the secondary path and correcting the inverse noise signal accordingly to provide a corrected inverse noise signal.

7. The electronic system of claim 5, wherein the active noise reduction controller is further configured to adjust parameters used by the digital filter in performing operations according to the corrected reference signal and the processed error signal, and further adaptively adjust the power level of the speaker control signal to reduce the error signal.

8. The electronic system as recited in claim 1, wherein the error microphone is disposed at an outlet of the fan module.

9. The electronic system of claim 1, wherein the active noise reduction controller is further configured to:

measuring an actual frequency response of a signal transfer path between the speaker module and the error microphone; and

the inverse noise signal is corrected according to the actual frequency response to provide a corrected inverse noise signal.

10. The electronic system of claim 2, wherein the active noise reduction controller is further configured to:

receiving an estimated frequency response of a signal transfer path between the speaker module and the error microphone from the embedded controller; and

the reference signal is corrected according to the estimated frequency response to provide a corrected reference signal.

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