阅读说明：本技术 为音频放大器供电的方法和音频放大器系统和扬声器系统 (Method for supplying power to an audio amplifier, audio amplifier system and loudspeaker system ) 是由 不公告发明人 于 2021-05-11 设计创作，主要内容包括：本发明涉及一种为音频放大器供电的方法,该方法包括以下步骤：在音频信号处理器中接收输入音频信号,在音频信号处理器中延迟输入音频信号以产生延迟的音频信号,通过分析输入音频信号以计算音频信号处理器中的功率需求估计,并由音频信号处理器根据功率需求估计为直流-直流转换器选择功率转换设置。该方法还包括以下步骤：将功率输入提供给直流-直流转换器,根据功率转换设置来转换功率输入以提供功率输出,使用功率输出为音频放大器供电,以及从音频信号处理器向音频放大器提供延迟的音频信号,以产生放大的音频信号。本发明还涉及音频放大器系统和扬声器系统。(The invention relates to a method for supplying power to an audio amplifier, comprising the following steps: the method includes receiving an input audio signal in an audio signal processor, delaying the input audio signal in the audio signal processor to produce a delayed audio signal, calculating a power demand estimate in the audio signal processor by analyzing the input audio signal, and selecting a power conversion setting for the dc-to-dc converter by the audio signal processor based on the power demand estimate. The method further comprises the following steps: the method includes providing a power input to a dc-to-dc converter, converting the power input according to a power conversion setting to provide a power output, powering an audio amplifier using the power output, and providing a delayed audio signal from an audio signal processor to the audio amplifier to produce an amplified audio signal. The invention also relates to an audio amplifier system and a loudspeaker system.)

1. A method of powering an audio amplifier (1), comprising the steps of:

receiving an input audio signal (2) in an audio signal processor (3);

-delaying the input audio signal (2) in the audio signal processor (3) to produce a delayed audio signal (4);

predicting a power demand estimate (5) by analyzing the input audio signal (2) to calculate the power demand estimate (5) in the audio signal processor (3);

the audio signal processor (3) selecting a power conversion setting (6) for a DC-DC converter (7) based on the power demand estimate (5);

-providing a power supply input (8) to the dc-dc converter (7);

switching the power input (8) according to the power switching setting (6) to provide a power output (9);

-powering the audio amplifier (1) using the power output (9);

-providing the delayed audio signal (4) from the audio signal processor (3) to the audio amplifier (1) to produce an amplified audio signal (10).

2. Method for powering an audio amplifier (1) according to claim 1, characterized in that the method comprises the step of charging an energy storage (11) using the power output (9), wherein the energy storage (11) stores energy of the power output (9) and distributes the energy to the audio amplifier (1), wherein the step of powering the audio amplifier (1) comprises using the power distributed by the energy storage (11).

3. A method of powering an audio amplifier (1) according to claim 2, wherein the energy storage (11) is based on one or more auxiliary capacitors (12) associated with the dc-dc converter (7).

4. A method of powering an audio amplifier (1) according to claim 1, wherein the step of delaying the input audio signal (2) comprises delaying the input audio signal (2) by a delay duration (27), wherein the delay duration (27) ranges from 1 to 100 milliseconds.

5. A method of powering an audio amplifier (1) according to claim 4, wherein the delay duration (27) ranges from 2 to 50 milliseconds.

6. A method of powering an audio amplifier (1) according to claim 4, wherein the delay duration (27) ranges from 5 to 20 milliseconds.

7. Method of powering an audio amplifier (1) according to claim 4, wherein the step of predicting the power demand estimate (5) comprises analyzing the input audio signal (2) within an analysis time window, wherein a ratio of a duration of the analysis time window and the delay duration (27) is in a range of 0.1 to 10.

8. Method of powering an audio amplifier (1) according to claim 7, wherein the ratio of the duration of the analysis time window and the delay duration (27) is in the range of 0.2 to 5.

9. Method of powering an audio amplifier (1) according to claim 7, wherein the ratio of the duration of the analysis time window and the delay duration (27) is in the range of 0.5 to 2.

10. A method of powering an audio amplifier (1) according to claim 7, wherein the step of predicting the power demand estimate (5) comprises calculating the power demand estimate (5) using the amplitude of the input audio signal (2).

11. A method of powering an audio amplifier (1) according to claim 10, wherein the step of predicting the power demand estimate (5) comprises calculating the power demand estimate (5) using a transducer impedance transfer function, wherein the transducer impedance transfer function is indicative of an impedance of a speaker transducer (17) receiving the amplified audio signal (10).

12. A method of powering an audio amplifier (1) according to claim 10, wherein the step of predicting the power demand estimate (5) comprises integrating the amplitude of the input audio signal (2) within the analysis time window to calculate the power demand estimate (5).

13. A method of powering an audio amplifier (1) according to claim 11, wherein the step of predicting the power demand estimate (5) comprises calculating the power demand estimate (5) by the formula

PDE＝∫TITF×IAS²dx，

Wherein PDE is the power requirement estimate (5), TITF is the transducer impedance transfer function, IAS is the input audio signal (2), and integration is performed on the basis of the input audio signal (2) within the analysis time window.

14. A method of powering an audio amplifier (1) according to claim 1, wherein the step of selecting the power conversion setting (6) comprises selecting an output voltage of the power output (9) using a voltage transfer function (13), wherein the voltage transfer function (13) is based on the power demand estimate (5).

15. A method of powering an audio amplifier (1) according to claim 14, wherein the voltage transfer function (13) is based on a voltage look-up table.

16. A method of powering an audio amplifier (1) according to claim 1, wherein the step of selecting the output voltage is based on a peak amplitude of the input audio signal (2).

17. A method of powering an audio amplifier (1) according to claim 1, wherein the step of selecting the power conversion setting (6) comprises selecting a maximum output current of the power output (9) using a current transfer function (14), wherein the current transfer function (14) is based on the power demand estimate (5).

18. A method of powering an audio amplifier (1) according to claim 17, wherein the current transfer function (14) is based on a current look-up table.

19. A method of powering an audio amplifier (1) according to claim 1, wherein the method comprises applying a dynamic range compression (15) to any of the input audio signal (2,2') and the delayed audio signal (4) in the audio signal processor (3), wherein the dynamic range compression (15) is based on the power requirement estimation (5).

20. A method of powering an audio amplifier (1) according to claim 1, wherein the use of amplifier power of the audio amplifier is measured, and wherein the power conversion setting (6) is based on the use of the amplifier power.

21. A method of powering an audio amplifier (1) as claimed in claim 1, wherein the dc-dc converter (7) is a switched-mode boost converter.

22. An audio amplifier system (30) comprising:

an audio signal processor (3) for receiving an input audio signal (2,2') and providing an output audio signal (4) based on the input audio signal (2, 2');

a DC-DC converter (7) powered by a power input (8) for converting the power input (8) to provide a power output (9);

an audio amplifier (1) powered by the power output (9) for amplifying the output audio signal (4) to generate an amplified audio signal (10);

characterized in that the audio signal processor (3) comprises:

-an audio signal delay operation (18) for generating the output audio signal (4) by delaying the input audio signal (2, 2');

an audio signal analysis operation (20) for calculating a power demand estimate (5) from the amplitude of the input audio signal (2,2') and outputting a power conversion control output (6) in dependence on the power demand estimate (5);

wherein the DC-DC converter (7) receives the power conversion control output (6) and converts the power input (8) in accordance with the power conversion control output (6) to provide the power output (9).

23. Audio amplifier system (30) according to claim 22, wherein the audio amplifier system (30) is arranged for performing a method of powering an audio amplifier (1) according to claim 1.

24. A speaker system (31) comprising:

a loudspeaker transducer (17);

the audio amplifier system (30) of claim 24,

wherein the amplified audio signal (10) is provided to the speaker transducer (17) to reproduce the amplified audio signal (10) as sound pressure waves.

Technical Field

The invention belongs to the technical field of power supply for an audio amplifier, and particularly relates to a loudspeaker system based on an audio amplifier system.

Background

Powering an audio amplifier with a power converter typically results in the power converter requiring a high peak current due to the high peak factor of typical audio signals. This is particularly problematic in current-limited systems. The audio power output of these systems may therefore be severely limited and may therefore have significant audio distortion.

Furthermore, based on the current demand of the audio signal, the power converter does not have to operate at its maximum power efficiency, its operating current and operating voltage are typically lower than its maximum current and voltage output.

Furthermore, since resistive losses are proportional to the square of the current, high peak factors of the audio signal result in relatively high resistive losses.

US patent application US2015/0349737 teaches boosting the voltage level of the battery to a boosted voltage level across a boost capacitor at the output of the boost stage, the current not exceeding a preselected one of the input current limits, and the boosted voltage level being higher than the voltage level of the battery and higher than the supply voltage required by the audio amplifier to output a predefined maximum peak power to the load.

Disclosure of Invention

The inventors have made the following invention after finding the above-mentioned problems and challenges relating to the audio amplifier. The invention can improve the efficiency and audio power of the audio amplifier system.

The invention relates to a method for supplying power to an audio amplifier, comprising the following steps: the method includes receiving an input audio signal in an audio signal processor, delaying the input audio signal in the audio signal processor to produce a delayed audio signal, calculating a power demand estimate in the audio signal processor by analyzing the input audio signal, and selecting a power conversion setting for the dc-to-dc converter by the audio signal processor based on the power demand estimate. The method further comprises the following steps: the method includes providing a power input to a dc-to-dc converter, converting the power input according to a power conversion setting to provide a power output, powering an audio amplifier using the power output, and providing a delayed audio signal from an audio signal processor to the audio amplifier to produce an amplified audio signal.

In an exemplary embodiment of the invention, the audio signal processor is a digital signal processor receiving an input audio signal. The signal is analyzed over an analysis time window of 10 milliseconds to predict a power demand estimate by integrating the squared magnitude of the signal divided by the impedance. Based on this, a power conversion setting of the dc-dc converter is selected by selecting an output voltage and a maximum output current of the dc-dc converter. In this embodiment, the dc-dc converter is a switch-mode boost converter powered by a current-limited battery and receives an input from the audio signal processor, wherein the input is indicative of a selected power conversion setting such that the dc-dc converter operates at a corresponding output voltage and maximum output current. In the audio signal processor, the input audio signal is delayed by 10 milliseconds to generate a delayed audio signal. The delayed audio signal is provided to an audio amplifier that is powered by the output of the dc-to-dc converter and produces an amplified audio signal. When the input audio signal includes a large peak, the calculated power demand increases, and therefore the output voltage of the dc-dc converter also increases, and energy is stored in at least one capacitor associated with the dc-dc converter. When the peak reaches the audio amplifier as a delayed audio signal, the audio amplifier uses the stored energy to properly amplify the peak and generate an amplified audio signal with minimal distortion while maintaining a fixed or a range of input currents.

By dynamically predicting the power demand estimate and selecting power conversion settings according to embodiments of the invention, the dc-dc converter can be operated with the best possible efficiency without compromising sound quality, which is advantageous for system efficiency in general.

Furthermore, delaying the audio signal may improve the flattening of the peak current demand curve, especially when the dc-dc converter is associated with an energy storage. Due to the equality of the power dissipated in the resistive circuit and said currentIn proportion, i.e. P ═ IV ═ I²R, therefore, the smoothing of the input current reduces power consumption, so delaying the audio signal may minimize power consumption. By dynamically predicting the power demand estimate and selecting the power conversion settings, peak current, the peak current demand of the dc-dc converter can be reduced, and therefore power consumption can be minimized without compromising sound quality, which is advantageous.

It is therefore an object of embodiments of the described invention to reduce the crest factor of the input current of a dc-dc converter to reduce power consumption.

In general, reducing power consumption is advantageous for any type of device, but is particularly useful for current limiting devices, such as battery powered devices connected through a USB connection or through an ethernet connection. In such a device, the invention may be utilized to increase the audio power output, extending the range of applications of the device, which is advantageous. Furthermore, in battery powered devices, the invention may be used to extend battery life, which is advantageous.

Features of the present invention include its ability to operate a boost converter, such as a switch mode boost converter, with optimum efficiency compared to the prior art. Furthermore, the invention may avoid unnecessarily fast charging of the energy store at high currents to further reduce power consumption, since the current limit control will charge the energy store at the required minimum current. Enveloping the audio signal within the allowed delay time.

Predicting the power demand reduces the crest factor of the power demand of the DC-DC converter compared to tracking the output voltage of the audio amplifier, thereby significantly improving efficiency and audio output power.

One aspect of the invention relates to an audio amplifier system comprising: an audio signal processor configured to receive an input audio signal and to provide an output audio signal based on the input audio signal; a DC-DC converter powered by the power input and arranged to convert the power input to provide a power output; and an audio amplifier powered by the power output and arranged to amplify the output audio signal to produce an amplified audio signal. The audio signal processor includes a delay operation that generates the output audio signal by delaying the input audio signal, and an audio signal analysis operation that calculates a power requirement estimate based on the magnitude of the input audio signal to output a power conversion control output based on the latter. The DC-DC converter receives the power conversion control output and converts the power control output according to the power to provide power output.

The output audio signal may thus be understood as a delayed audio signal. The power conversion control output may be understood as a communicated representation of the power conversion setting and may therefore indicate, for example, a dc level or voltage.

In embodiments of the invention, the audio amplifier system may perform any of the methods of the invention. Thus, the audio amplifier system may comprise any elements necessary to perform any of the methods.

Any audio amplifier system according to said invention may have the same advantages as the method of said invention.

An aspect of the invention relates to a speaker system. The loudspeaker system comprises a loudspeaker transducer to which the amplified audio signal is supplied, and an audio amplifier system according to the invention which reproduces the amplified audio signal as sound pressure waves.

In an embodiment of the invention, the loudspeaker system may perform any one of the methods of the invention. Thus, the loudspeaker system may comprise any elements necessary for performing any of the methods of the invention.

Any loudspeaker system according to the invention may have the same advantages as the method according to the invention.

Drawings

Various embodiments of the present invention will now be described with reference to the accompanying drawings, in which

FIG. 1 shows an exemplary embodiment of the present invention;

FIG. 2 shows another exemplary embodiment of the present invention;

3 a-3 d show audio signal processing and energy storage in one embodiment of the invention;

4 a-4 b illustrate representations of an exemplary voltage transfer function and an exemplary current transfer function in one embodiment of the present invention;

FIG. 5 illustrates a method according to an embodiment of the present invention.

Description of the element reference numerals

1 Audio Amplifier 2,2' input Audio Signal

3 audio signal processor 4 delayed audio signal

5 Power demand estimation 6 Power supply transition settings

7 dc-dc converter 8 power input

9 power output 10 amplified Audio Signal

11 energy store 12 auxiliary capacitor

13 voltage transfer function 14 current transfer function

15 dynamic range compression 16 cell

17 speaker transducer 18 audio signal delay operation

19 dynamic range compression transfer function 20 audio signal analysis operation

21 output voltage representation 22 maximum output current representation

23 peak detection analysis 24 addition

25 amplifier power usage measurement 26 stored energy

27 delay duration 28 equalization filter

29 audio signal peak structure 30 audio amplifier system

31 speaker system S1-S8 method steps

Detailed Description

In this application, the power requirement estimation may be considered as a calculation result showing the power required to amplify the delayed audio signal in the audio amplifier. The required power may be accumulated power, accounting for energy stored in the energy storage. For example, the power requirements may increase before the audio amplifier needs to be powered. The calculation of the power requirements is performed in the audio signal processor and therefore the calculation can be done digitally.

The setting of the power conversion may refer to one or more controllable output settings or parameters of the dc-dc converter. The power conversion setting may be indicative of an output voltage, an output current, a maximum output voltage, a maximum output current, and/or a conversion efficiency of the dc-dc converter. For example, in some embodiments of the present invention, selecting a power conversion setting includes selecting an output voltage. In some other embodiments of the present invention, selecting a power conversion setting includes selecting an output current or a conversion mode. In some other embodiments of the present invention, selecting the power conversion setting includes selecting an output voltage and a maximum output current. It is noted, however, that the power conversion arrangement according to the invention is not limited to these examples.

A dc-dc converter may refer to an electronic circuit or an electromechanical device that converts a dc source from one voltage level to another. In an exemplary embodiment of the invention, the dc-dc converter is arranged to increase the voltage level while correspondingly decreasing the current level. The dc-dc converter of the invention should be at least partly controllable, for example in that the output voltage is controllable. In some embodiments of the invention, the dc-dc converter is a switched-mode boost converter. The invention is not limited to this embodiment, however, the dc-dc converter may also be a SEPIC converter,a converter, or a flyback converter.

The audio signal processor in the present invention may be a digital signal processor in general, but the present invention is not limited to this embodiment, and it may perform necessary operations based on an analog circuit.

In embodiments of the present invention, various power, voltage, current, digital, and/or analog signals may be communicated within and between elements of an embodiment by means of wired or wireless communication. For example, in an embodiment where the audio signal processor is a digital signal processor, the communication performed within the digital signal processor is mainly digitized, but the digital signal processor may also receive and output analog signals, such as an input audio signal and a delayed audio signal, through an analog-to-digital converter and a digital-to-analog converter. In another example, the dc-dc converter may be controlled/regulated by an analog signal provided by the audio signal processor and input and output power at the same time. Thus, the power, signals, and their communications in this application are not limited to a particular type.

Fig. 1 shows an exemplary embodiment of the present invention. The audio amplifier 1 is here supplied by a dc-dc converter 7 regulated by the audio signal processor 3. This adjustment ensures that the audio amplifier 1 is provided with sufficient power with efficient power conversion and minimal audio distortion.

The audio signal processor 3 is a digital signal processor 3. Here, the input audio signal 2 is delayed by applying an audio signal delay operation 18 to generate a delayed audio signal 4, which delayed audio signal 4 is provided to the audio amplifier 1.

The input audio signal 2 is analyzed in an audio signal analysis operation 20 to calculate a power demand estimate 5. In some embodiments, the power requirement estimate 5 is calculated based on the amplitude of the input audio signal 2, which may be the squared amplitude of the signal, which may be the integral of the squared amplitude of the signal within some analysis time window, which matches the delay time, or which corresponds to a significant fraction of the delay window. When performing the power estimation calculation, the system impedance transfer function compensation may also be applied to the signal to represent the impedance of the speaker system.

Based on the power demand estimate 5, a power conversion setting 6 for the dc-dc converter 7 is selected. In the embodiment shown, the power conversion arrangement 6 is related to the output voltage of the power output 9 of the dc-dc converter 7; at this time, if the power conversion setting 6 is changed, the output voltage is also changed. The dc-dc converter 7 receives a power input 8 and converts it to a power output 9 according to the power conversion settings 6.

The power output 9 is provided to the audio amplifier 1 to power it. The audio amplifier 1 also receives a delayed audio signal 4 which is arranged to be amplified using a power output 9. In this exemplary embodiment, the delay on the delayed audio signal 4 ensures that the analysis in the audio signal processor 3 can be carried out smoothly and that the output voltage can be adjusted so that any delayed output signal 4 sent to the audio amplifier 1 can be amplified accordingly with the adjusted output voltage to produce the amplified audio signal 10.

In some embodiments of the invention there is a delay in the audio signal 4 applied to the input audio signal 2 to produce the delayed audio signal so that the dc-dc converter 7 can store the energy before the energy is used by the audio amplifier 1. For example, if the input audio signal 2 comprises a signal peak of large amplitude, the delay ensures that the energy storage can be charged before the signal peak reaches the audio amplifier 1. When a signal peak in the delayed audio signal 4 reaches the audio amplifier 1, the audio amplifier 1 may amplify the delayed audio signal 4 with the stored energy. An appropriately timed and regulated energy store may reduce the magnitude of the peak current demand of the power input 8, as the controller will only select the minimum peak current required to reach a certain voltage value on the output capacitor that can meet the peak voltage and peak power requirements of the upcoming audio waveform.

Due to the audio signal delay operation 18, the prediction of the power demand estimate 5, and the selection of the power conversion setting 6, the dc-dc converter 7 can be operated at a setting that is most favorable for conversion efficiency. The storage of energy makes it possible to reduce the peak current requirements of the power input 8, further increasing the effectiveness of the system and increasing the audio power output.

Fig. 2 shows another embodiment of the present invention. The embodiment of fig. 2 has some elements added to the embodiment shown in fig. 1.

The input audio signal 2' is first filtered in an equalization filter 28 before the dynamic range compression 15. The equalization filter 28 may be used to compensate for transfer functions, such as the transfer function of the speaker transducer 17 and/or the acoustic environment of the system. The equalization filter 28 may be preprogrammed into the audio signal processor 3 or may be adjustable by a user of the system.

The dynamic range compression 15 is controlled at least in part by the audio signal analysis operation 20 and computationally predicts a power demand estimate. In this embodiment, the dynamic range compression transfer function 19 adjusts the dynamic range compression 15 (which may be based on a look-up table). The transfer function 19 converts the calculated power demand estimate 5 into a compression upper amplitude threshold for dynamic range compression 15. The amplitude of the input audio signal 2' above the threshold is reduced. In this way, adjusting the dynamic range compression 15 may minimize distortion of the amplified delayed audio signal 4 due to insufficient power supplied to the audio amplifier 1, which may occur in audio signals of a substantially long duration.

Due to the effect of the equalization filter 28 and the dynamic range compression 15, the input audio signal 2' initially provided to the audio signal processor 3 and the predicted input audio signal 2 for the power demand estimation 5 are not necessarily identical. However, in the present application the term "input audio signal" may be used to refer to any of the input audio signals 2, 2'.

The input audio signal 2 is delayed by an audio signal delay operation 18 to generate a delayed audio signal 4.

In the audio signal analysis operation 20, the power demand estimate 5 is predicted by calculation. The calculated power demand estimate 5 is used as a basis for selecting the power conversion settings for the dc-dc converter 7 and dynamic range compression. The audio signal analysis operation 20 uses a portion of the input audio signal 2 that is within a certain analysis time window for analysis based on the input audio signal 2. The duration of the analysis time window is close to the duration of the delay of the input audio signal 2 in the audio signal delay operation 18 to generate the delayed audio signal 4. The squared magnitude of the input audio signal is integrated over an analysis time window to calculate a power demand estimate 5. In various embodiments of the present invention, the integration is performed in the time domain and/or the frequency domain. The calculation may further take into account the amplifier transfer function and/or the transducer impedance transfer function, and may further utilize models and/or measurements of external sensor inputs or system component temperatures to improve the accuracy of the power prediction.

In the illustrated embodiment, the audio signal analysis operation 20 also receives input of an amplifier power usage measurement 25, and the power demand estimation 5 may rely on this measurement 25. For example, the power demand estimate 5 is calculated based on one or more prediction coefficients indicative of the power demand of the audio amplifier 1. The prediction coefficient may be a pre-factor or an offset in the integration of the input audio signal 2. The amplifier power usage measurements 25 can then be used to update any prediction coefficients to ensure the accuracy and precision of the power demand estimate 5.

In other embodiments of the present invention, the amplifier power usage measurement 25 may be used to select the power conversion setting 6. The power demand estimation 5 is not based on the amplifier power usage measurement 25, but the voltage transfer function 13 and/or the current transfer function 14 are based on the amplifier power usage measurement 25.

The calculated power demand estimate 5 may be used as an input to the voltage transfer function 13, the current transfer function 14, and the dynamic range compression transfer function 19. In the voltage transfer function 13, the temporary output voltage is set based on the power demand estimation 5. In the current transfer function 14, the maximum output current is set. Similarly, in the dynamic range compression transfer function 19, a compression upper limit amplitude threshold value of the dynamic range compression 15 is set. Each of these transfer functions 13,14, 19 may be based on a separate look-up table or mathematical function, thereby converting a certain value of the power demand estimate 5 into a certain output of each transfer function 13,14, 19.

The power conversion arrangement 6 is established based on the output of the voltage transfer function 13 and the current transfer function 14. The power conversion arrangement 6 comprises an output voltage representation 21 and a maximum output current representation 22, which output voltage representation 21 and maximum output current representation 22 are passed to the dc-dc converter 7 for regulation and control.

The output voltage and its representation 21 is based on the output of the voltage transfer function 13 (i.e. the tentative output voltage) and also on the peak detection analysis 23. In peak detection analysis 23, the input audio signal 2 is analyzed to detect the presence of any peaks within the analysis time window having an amplitude greater than a peak amplitude threshold. The peak detection analysis 23 provides an output which is added to the temporary output voltage in an addition operation 24. Upon detection of an audio signal peak having an amplitude greater than a threshold, a peak voltage offset provided by the peak detection analysis is added to the temporary output voltage to produce an output voltage. If there is no such peak within the analysis time window, no peak voltage offset is added, when the output voltage is equal to the temporary output voltage.

The power conversion arrangement 6 (i.e. the representation of the output voltage 21 and the representation of the maximum output current 22) is provided to the dc-dc converter 7 to regulate it. In this embodiment, the dc-dc converter receives a power input 8 provided by a battery 16, but it is noted that other power sources may be used according to other embodiments of the invention. The dc-dc converter converts the power input 8 into a power output 9. For example, the dc-dc converter 7 is based on a switched-mode boost converter that can increase the voltage of the power input 8 to generate the power output 9. Accordingly, the current of the power output 9 is typically lower than the current of the power input 8. Switched mode boost converters can typically be regulated by varying the duration of the switch opening and/or closing, such as by altering the duty cycle.

The dc-dc converter 7 may further include a filter. The filter may be made of a capacitor to reduce noise such as voltage ripple. The dc-dc converter 7 may further comprise stabilizing means, such as a PID controller (proportional integral derivative controller), which ensures stabilization of the power output of the dc-dc converter 7.

The dc-dc converter 7, such as a switched-mode boost converter, may have a built-in energy storage, e.g. a capacitor. The capacitor is necessary for the operation of the dc-dc converter 7. As shown in fig. 2, the dc-dc converter 7 is also connected to an energy storage 11 based on an auxiliary capacitor 12. The energy storage 11 may be used to store energy of the power output 9 when the output of the energy storage 11 is larger than the power requirement of the audio amplifier 1.

The audio amplifier 1 receives power from the dc-dc converter 7 and the energy storage 11 to amplify the delayed audio signal 4 into an amplified audio signal 10. The amplified audio signal 10 is supplied to a speaker transducer 17, and the speaker transducer 17 reproduces the amplified audio signal 10 as sound pressure waves.

Due to the audio signal delay operation 18, the prediction of the power demand estimate 5, and the selection of the power conversion setting 6, the dc-dc converter 7 can be operated at a setting that is most favorable for conversion efficiency. The storage of energy may reduce the peak current requirements of the power input 8, further improving the efficiency of the system and increasing the audio power output.

Fig. 3 a-3 d show audio signal processing and energy storage in an embodiment of the invention. These four figures show exemplary representations of the input audio signal 2, the delayed audio signal 4, the power demand estimate 5 and the stored energy 26, respectively. In each figure, the delay duration 27 is shown for comparison. The x-axis in each figure is the time axis, where the progression of time occurs in a direction from left to right.

The curves shown in fig. 3 a-3 d indicate how signal processing and energy storage may occur in some embodiments of the invention, for example, in the embodiment shown in fig. 2.

Fig. 3a shows an exemplary input audio signal 2 of the audio amplifier system, e.g. the envelope of the input audio signal 2. Initially, the amplitude of the input audio signal is relatively low, with several small peaks of low amplitude; subsequently, a local audio signal peak structure 29 occurs; and then a low amplitude peak appears.

Fig. 3b shows an exemplary delayed audio signal 4 based on the input audio signal shown in fig. 3a, e.g. the envelope of the delayed audio signal 4 based on the input audio signal shown in fig. 3 a. The delayed audio signal 4 is shifted in time corresponding to the delay duration 27. For ease of comparison, the delay duration has been marked in the figure. The delayed audio signal 4 is then substantially similar to the input audio signal 2, having a similar audio signal peak structure 29, but delayed in time.

Fig. 3c shows an exemplary power demand estimate 5 based on the input audio signal 2, wherein the power demand estimate increases in the direction of the y-axis in fig. 3 c. Each point in the power demand estimation 5 curve is generated based on the integration of the input audio signal 2 in an analysis time window that extends backwards in time and has the same length as the delay duration 27 shown. The input audio signal 2 increases, the power demand estimate 5 also increases, and when the amplitude of the input audio signal 2 decreases, the power demand estimate 5 also decreases, but with a delay corresponding to the delay duration 27. Thus, the illustrated power demand estimate 5 initially increases relatively slowly, and then the power demand estimate 5 increases significantly at the audio signal peak structure 29 of the input audio signal 2 and subsequently decreases at the audio signal peak structure 29 of the delayed audio signal 4. The curve of the power demand estimate 5 has a top hat shape determined by the duration of the analysis time window and the audio signal peak structure 29.

Fig. 3d shows the variation with time of the stored energy 26 in the y-direction on fig. 3d, which stored energy 26 is based on the delayed audio signal 4 and the power demand estimate 5. The power demand estimation 5 determines the power output 9 of the dc-dc converter 7. The power output is provided to an audio amplifier and an energy storage. The audio amplifier receives the delayed audio signal and uses the power supply accordingly. The energy store is in the energy store (e.g., energy store 11 in fig. 2) when the power provided by the dc-dc amplifier is greater than the power used by the audio amplifier, and the audio amplifier is at least partially powered by the energy stored in the energy store when the power provided by the dc-dc amplifier is less than the power used by the audio amplifier. Thus, the amplitude of the power demand estimate 5 increases the stored energy 26, while the amplitude of the delayed audio signal 4 decreases the stored energy 26. Thus, in fig. 3d, the stored energy is initially relatively flat. As the power demand increases near the audio signal peak structure 29 of the input audio signal 2, the stored energy 26 also starts to gradually increase. When the delayed audio signal 4 has a smaller amplitude, the stored energy 26 continues to grow. The stored energy 26 decreases rapidly around the audio signal peak structure 29 of the delayed audio signal 4. In the example shown here, the audio amplifier requires more energy than is provided by the dc-dc converter alone, and therefore also uses the stored energy 26. Note that after the audio signal peak structure 29 of the delayed audio signal 4, the stored energy is reduced again. Thus, the power demand estimate is relatively accurate in view of the actual power demand, and therefore sufficient energy is stored before the audio signal peak structure 29 is amplified.

The graphical representations shown in fig. 3 a-3 d show the delayed input audio signal 4, the calculated power demand estimate 5, and how the energy 26 is stored and dispersed in the energy storage in one embodiment of the invention. Note that this curve and its shape are illustrative examples and should not be construed as limiting the invention. The signal processing and energy storage can thus be varied in a number of ways within the scope of the invention as specified in the claims.

Fig. 4 a-4 b show representations of an exemplary voltage transfer function 13 and an exemplary current transfer function 14 according to an embodiment of the invention.

The curves 13,14 shown in fig. 4 a-4 b indicate how the signal processing takes place in some embodiments of the invention, e.g. in the embodiment shown in fig. 2.

The horizontal direction (i.e., the x-axis direction) in both figures represents the input power demand estimate, where the input power demand estimate increases in the direction along the horizontal arrow. In fig. 4a, the vertical direction (i.e., the y-axis direction) represents the output voltage of the dc-dc converter, which increases in the direction of the vertical arrow, and in fig. 4b, the vertical direction represents the maximum output current of the dc-dc converter, which increases in the direction of the vertical arrow.

According to some embodiments of the invention, when the power demand estimate 5 has been calculated, the selection of the power conversion arrangement 6 comprises selecting an output voltage and/or a maximum output current through the voltage transfer function 13 and the current transfer function 14. For example, the power demand estimate 5 may correspond to a point on the vertical axis in fig. 4 a-4 b at which the corresponding output voltage and the corresponding maximum output current are selected.

Note that the shapes of the exemplary voltage transfer function 13 and the exemplary current transfer function 14 of fig. 4a and 4b are complementary to each other, such that an increase in the power demand estimate will always result in an increase in the output voltage or maximum output current. The shape of the transfer functions 13,14 ensures that the dc-dc converter operates at the optimum maximum current over a wide range of power demand estimates. Furthermore, the shape of the transfer functions 13,14 also ensures that the output voltage never falls below a minimum value.

According to some embodiments of the invention, the transfer functions 13,14 are based on look-up tables. According to some other embodiments of the invention, the transfer functions 13,14 are based on mathematical functions, such as piecewise linear functions.

It is noted that the curves of fig. 4 a-4 b and their shapes are illustrative examples and should not be construed as limiting the invention. The signal processing may thus be varied in a number of ways within the scope of the invention as specified in the claims.

Fig. 5 shows a method according to an embodiment of the invention. The method comprises eight steps S1-S8.

In a first step S1 of the method, an input audio signal is received in an audio signal processor.

In a next step S2 of the method, the audio signal is delayed in the audio signal processor to generate a delayed audio signal.

In the next step S3 of the method, a power demand estimate is predicted. The power demand estimate is calculated by analyzing the input audio signal in an audio signal processor.

In a next step S4 of the method, the audio signal processor selects a power conversion setting for the dc-dc converter based on the power requirement estimate. The power conversion setting may be indicative of an output voltage of the dc-dc converter.

In a next step S5 of the method, the power input is provided to the dc-dc converter, i.e. the dc-dc converter is powered by the power input.

In a next step S6 of the method, the power input is converted to a power output according to the power conversion setting.

In a next step S7 of the method, the power output is used to power an audio amplifier.

In a next step S8 of the method, the delayed audio signal is provided by the audio signal processor to an audio amplifier to generate an amplified audio signal. Amplifying the power based on the power output.

Note that the present invention is not limited to a particular order of steps.

Various embodiments of the present invention are presented below without reference to the specific figures:

in one embodiment of the invention, the method of the invention comprises the step of charging an energy storage with the power output, wherein the energy storage is arranged to store energy of the power output and to distribute the energy to the audio amplifier, wherein the step of powering the audio amplifier comprises using the power distributed by the energy storage.

In typical embodiments, the energy storage is used to store the remaining power, which is the remaining power provided by the dc-dc converter and not used by the audio amplifier; similarly, the energy storage provides power to the audio amplifier when the dc-dc converter itself cannot provide sufficient power. In this way, the energy storage may facilitate smoothing of the current demand, which is advantageous as it may reduce power consumption and increase audio power output.

In some embodiments, the energy storage is integrated in the dc-dc converter by incorporating one or more capacitors in the switch-mode boost converter.

In one embodiment of the invention, the energy storage is based on one or more auxiliary capacitors associated with the dc-dc converter.

Capacitors are suitable as the energy storage of the present invention, since capacitors may facilitate a rapid alternation of storage and dispersion of electrical energy as required by exemplary embodiments of the present invention.

In an embodiment of the invention, the step of delaying the input audio signal comprises delaying the input audio signal by a delay duration, wherein the delay duration is in the range from 1 millisecond to 100 milliseconds, such as from 2 milliseconds to 50 milliseconds, such as from 5 milliseconds to 20 milliseconds, such as 10 milliseconds.

In an embodiment of the invention, the step of predicting the power demand estimate comprises analyzing the input audio signal within an analysis time window, wherein a ratio between a duration of the analysis time window and the delay time is in a range of 0.1 to 10, such as 0.2 to 5, such as 0.5 to 2, such as 1.

In an exemplary embodiment of the invention, the delay duration and the duration of the analysis time window are the same, e.g. 10 ms or 15 ms. However, the two durations may also be different, for example 20 milliseconds and 30 milliseconds respectively.

The duration of the window should be sufficient for performing the analysis and implementing the power conversion settings for the dc-dc converter.

Furthermore, the duration of the time window may also facilitate energy to be stored. For example, when a typical audio peak occurs in the input audio signal, the energy store may store sufficient energy for the duration of the delay to amplify the peak as it reaches the audio amplifier through the delayed audio signal.

In typical embodiments, the analysis time window is continuously updated, and the duration between two updates of the analysis time window is significantly shorter than the duration of the analysis time window. For example, in one embodiment, the duration of the analysis time window is 5 milliseconds, but is updated every 0.5 milliseconds. Thus, a new power demand estimate is calculated every 0.5 milliseconds.

In one embodiment of the invention, predicting the power demand estimate comprises calculating the power demand estimate using the amplitude of the input audio signal.

The power consumption of an audio amplifier is typically dependent on the amplitude of the audio signal to be amplified. Therefore, it is advantageous to take the amplitude of the audio signal into account when calculating the power requirement estimate.

The calculations involving the amplitude may further include calculating an absolute value of the amplitude, calculating a square value of the amplitude, finding a peak value of the amplitude, identifying audio signals having amplitudes greater than an amplitude threshold, and the like.

In an embodiment of the invention, predicting the power demand estimate comprises calculating the power demand estimate using an amplifier transfer function, wherein the amplifier transfer function is related to the audio amplifier.

The power consumption of an audio amplifier may depend on the frequency of the audio signal. It is therefore advantageous to take into account the characteristics of the audio amplifier, such as the power requirement estimate can be calculated by the amplifier transfer function.

In one embodiment of the invention, predicting the power demand estimate comprises calculating the power demand estimate using a transducer impedance transfer function, wherein the transducer impedance transfer function is indicative of an impedance of a speaker transducer, wherein the speaker receives the amplified audio signal.

The ability of a loudspeaker transducer to convert electrical energy to acoustic energy is typically frequency dependent. The conversion efficiency of the speaker transducer will affect the power used by the amplifier. Therefore, it is advantageous to consider the transducer impedance transfer function when calculating the power demand estimate.

In one embodiment of the invention, predicting the power demand estimate comprises integrating the amplitude of the input audio signal over the analysis time window to calculate the power demand estimate.

Performing the integration is advantageous because it enables the shape of the input audio signal, e.g. the width of the audio signal peaks, to be taken into account, which is advantageous for accurately powering the audio amplifier.

In one embodiment of the invention, predicting the power demand estimate comprises calculating the power demand estimate by a formula. The formula is:

PDE＝∫TITF×IAS²dx，

wherein PDE is the power demand estimate, TITF is the transducer impedance transfer function, IAS is the input audio signal, and integration is performed based on the input audio signal within the analysis time window.

In some embodiments of the invention, the power demand estimate is calculated in the time domain, i.e. the integration variable dx indicates time. In some other embodiments of the invention, the power demand estimate is calculated in frequency space, i.e. the integral variable dx indicates the frequency. For example, a Fast Fourier Transform (FFT) is applied to the input audio signal within an analysis time window and the total power of the sensor is obtained by multiplying the FFT with the transducer impedance and integrating over all frequency bins.

Using the above formula to calculate the power requirement estimate is advantageous because the square of the input audio signal indicates the actual power required for amplification. In addition, the system impedance transfer function is considered in the calculation.

In one embodiment of the invention, the step of selecting the power conversion setting comprises changing a first power conversion setting to a second power conversion setting, wherein the first power conversion setting is associated with a first conversion efficiency of the dc-dc converter and the second power conversion setting is associated with a second conversion efficiency of the dc-dc converter, wherein the second conversion efficiency is greater than the first conversion efficiency.

Conversion efficiency may be understood as the power efficiency with which a dc-dc converter converts a power input into a power output.

Changing the first power conversion setting to the second power conversion setting to increase the efficiency of conversion of the power input to the power output is advantageous because it may reduce the power consumption of the dc-dc converter.

In one embodiment of the invention, the step of selecting the power conversion setting comprises selecting an output voltage of the power output using a voltage transfer function, wherein the voltage transfer function is based on the power demand estimate.

Selecting the output voltage of the dc-dc converter is advantageous because controlling the output voltage is a way to directly control the power consumption of the dc-dc controller and the associated energy storage of the audio amplifier. Estimating the voltage transfer function as an input with the power requirement is a flexible and simple way of selecting the output voltage.

In one embodiment of the invention, the voltage transfer function is based on a voltage look-up table.

In an embodiment of the invention, the voltage transfer function is based on a mathematical function.

The voltage look-up table is a flexible and simple voltage transfer function that is easy to implement in, for example, a digital signal processor. The voltage lookup table of the present invention is not limited to any particular shape or type and may be similar to a mathematical function, a piecewise function, or may reflect the optimum efficiency of the dc-dc converter.

In an embodiment of the invention, the selection of the output voltage is based on a peak amplitude of the input audio signal.

The selection of the output voltage based on the peak amplitude of the input audio signal may be combined with the calculated power demand estimate. For example, in one embodiment of the invention, a power demand estimate is calculated by integrating the input audio signal over an analysis time window, and the temporary output voltage is generated based on the power demand estimate. Further, peak detection analysis specifically analyzes the input audio signal to detect the presence of any audio peaks whose peak amplitude is above a peak amplitude threshold within an analysis time window. Upon detection of such a peak, a peak voltage offset is added to the temporary output voltage to produce an output voltage. The temporary output voltage is the output voltage if the amplitude of no audio peak exceeds the peak amplitude threshold. Thus, the method of this embodiment is able to detect the peak value and change the output voltage of the dc-dc converter accordingly.

As mentioned above, selecting the output voltage based on the peak amplitude of the input audio signal is advantageous because it allows a more accurate output voltage to be selected, which ensures both a high efficiency of the dc-dc converter and an accurate amplification of the delayed audio signal.

In an embodiment of the invention, the step of selecting the power conversion setting comprises selecting a maximum output current of the power output using a current transfer function, wherein the current transfer function is based on the power demand estimate.

Some dc-dc converters are associated with a controllable maximum output current of their power output. The maximum output current may be related to the power efficiency of the power conversion. Therefore, it is advantageous to actively select the maximum output current to improve efficiency while ensuring that sufficient current is available for the audio amplifier and/or the energy storage. The current transfer function with power demand as input is a flexible and simple way to select the maximum output current.

In one embodiment of the invention, the current transfer function is based on a current look-up table.

In an embodiment of the invention, the current transfer function is based on a mathematical function.

The current lookup table is a flexible and simple type of current transfer function that is easy to implement in, for example, a digital signal processor. The current lookup table according to the present invention is not limited to any particular shape or type, and may be similar to a mathematical function, a piecewise function, or may reflect the optimal efficiency of the dc-dc converter.

Typically, the voltage transfer function and the current transfer function should be used separately or in combination to ensure that the power output provided by the dc-dc converter is sufficient to power the audio amplifier, e.g., in combination with an associated energy store.

In one embodiment of the invention, the method of the invention comprises the steps of: applying an equalization filter to the input audio signal prior to predicting the power demand estimate.

Applying an equalization filter is advantageous because it allows the input audio signal to be changed to the frequency response of the audio amplifier system to adapt it to a particular application. The equalization filter should preferably be applied before predicting the power demand estimate, since the prediction should rely on the filtered input audio signal to calculate an accurate and precise power demand estimate.

Equalization filters may generally increase or decrease based on the energy of a particular frequency range of the input audio signal.

In one embodiment of the invention, the inventive method comprises the step of applying dynamic range compression to any of said input audio signal and said delayed audio signal in said audio signal processor, wherein said dynamic range compression is estimated based on said power requirement.

Some embodiments of the invention have limited capacity to store energy for the audio amplifier, or limited audio amplification range. In some of these embodiments, dynamic range compression of an audio signal may advantageously reduce audio distortion that may otherwise occur when a long audio signal with large amplitude is reached.

In embodiments of the present invention, dynamic range compression may be applied to an input audio signal or a delayed audio signal.

The Dynamic Range Compression (DRC)15 may be implemented by a transfer function (e.g., a look-up table).

If the DRC15 is implemented before the delay and the output of the DRC is input to the power estimate, the system may be provided with a power compression feedback loop that may allow the system to adjust the output power to a fixed level. This may be accomplished by triggering the DRC15 to compress the output when the system power prediction exceeds a certain level and allowing the DRC15 to stop only when the power prediction is below a certain level. This can be further improved by using a complete PID controller, or just PI or PD control. The power limit adjustment function is very useful for the power limiting system to achieve as high a sound output as possible.

It is advantageous to base the dynamic range compression on a power demand estimate, since the power demand estimate indicates the power required by the audio amplifier, which in turn indicates whether the audio amplifier has sufficient power.

In one embodiment of the invention, the amplifier power usage of the audio amplifier is measured and the power conversion setting is based on the amplifier power usage.

If the actual power usage of the audio amplifier is measured, for example by sensing the current and/or voltage supplied to the audio amplifier, the prediction of the selection of the power conversion setting can be improved. The power conversion settings may be selected based on prediction coefficients incorporated in the voltage transfer function or the current transfer function. The prediction coefficients may be updated periodically based on measured amplifier power usage to optimize accuracy and precision.

In some embodiments of the invention, the power conversion settings may be used indirectly based on amplifier power. For example, calculating the power demand estimate may be based on measured amplifier power usage and the power conversion setting based on the power demand estimate.

In one embodiment of the invention, the dc-dc converter is a boost converter.

A boost converter may be understood as a dc-dc converter which generates an output voltage which is greater than its input voltage/source voltage, i.e. its dc input voltage is lower than its output voltage. Accordingly, the output current is less than the input current.

The use of a boost converter is advantageous, because the voltage requirements in many applications are higher than the voltage of a power supply without a boost converter (e.g. a USB connection),

in an embodiment of the invention, the dc-dc converter is a switched-mode boost converter.

The use of a switch-mode boost converter is advantageous because it is simple, efficient and controllable. It may generally comprise at least one regularly switched transistor, a diode, and an inductor. It may also comprise a capacitor for, for example, storing energy. It may further comprise one or more filters, such as input/output filters, for reducing noise.

In one embodiment of the invention, the dc-dc converter is associated with a PID controller.

For example, the switch-mode boost converter may be connected to and at least partially controlled by a PID controller that ensures stabilization of the power/voltage/current output of the switch-mode boost converter.

In some embodiments, the PID controller is integrated in the dc-dc converter.

Stabilizing the output of the dc-dc converter is advantageous because it can ensure the correctness of audio amplification.

In one embodiment of the invention, the audio signal processor is a digital signal processor.

The use of a digital signal processor is advantageous because it makes the adaptation of the inventive method easier. Digital signal processors may typically have integrated analog-to-digital converters and digital-to-analog converters. The input audio signal may be provided to the digital signal processor by an analog-to-digital converter before processing the input audio signal. Similarly, the delayed audio signal may be provided to a digital-to-analog converter before being provided to an audio amplifier.

In one embodiment of the invention, the power input is provided by a battery.

In an embodiment of the invention, the power input is provided by a USB connection.

In one embodiment of the invention, the power input is provided over an ethernet connection.

Examples of power supplies such as USB connections, ethernet connections and current limited batteries are of interest to the present invention because the current available in the present invention is limited. Furthermore, the power limit may be adapted to the state or quality of the power supply, e.g. if the battery is in a low state of charge, the internal resistance may increase, where the power output may be more limited than when the battery is in a high state of charge. For example, USB or ethernet power supplies have power negotiation protocols that limit the power supply to different levels depending on the functionality of the source device.

In one embodiment of the invention the inventive method comprises the step of providing said amplified audio signal to a loudspeaker transducer, which reproduces said amplified audio signal as sound pressure waves.

In one embodiment of the invention, an audio amplifier system may perform any of the disclosed methods of the invention. Thus, the audio amplifier system may comprise any elements necessary for performing any of the disclosed methods.

Any audio amplifier system according to the invention may have the same advantages as the method in the invention.

In one embodiment of the invention the audio amplifier system comprises a loudspeaker transducer, such that the audio amplifier system is a loudspeaker system, wherein the amplified audio signal is provided to the loudspeaker transducer, which reproduces the amplified audio signal as sound pressure waves.

Any loudspeaker system according to the invention may have the same advantages as the method of the invention.

Embodiments of the invention may include various processing parameters and combinations of system elements, such as analysis operations, delay durations, durations of analysis time windows and their timing relative to the delay durations, transfer functions, capacitors, power supplies, dc-dc converters, and the like. For various embodiments, the system elements and parameters described above may be selected to tailor the audio amplifier system for a particular application. This selection may be performed by a person skilled in the art to control the audio output power, distortion, power consumption, processing power, analysis quality, delay, etc. within a certain range. Thus, the implementation of embodiments of the invention may vary depending on the actual application of the audio amplifier system.

As is apparent from the above, the present invention relates to a method and system for powering an audio amplifier. By delaying the input audio signal before it is provided to the audio amplifier, the input audio signal may be analyzed to predict a power demand estimate. Based on this estimate, a power conversion setting, such as the output voltage of a dc-dc converter powering the audio amplifier, may be set. Any remaining output power of the dc-dc converter may be stored in the energy storage. The invention can realize the optimal DC-DC converter operation and store energy, thereby reducing resistance loss and increasing audio output power.

The above embodiments are merely illustrative of the principles and utilities of the present application and are not intended to limit the application. It is noted that detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of the present application.