Online Detection Device and Method for Speaker Load Short Circuit and Open Circuit Based on Class D Power Amplifier

Abstract

The application discloses a loudspeaker load short-circuit and open-circuit online detection device and method based on a class-D power amplifier, which comprises a current collection module, a current prediction module, a comparator and a fault decision module, the input end of the comparator is used for comparing the collected upper tube current and lower tube current with the predicted current I EXPECT after the comparison of the collected upper tube current and lower tube current with the predicted current by the comparator, the result is judged by the fault decision module, and the corresponding feedback signal is sent. The detection scheme does not interfere with the sound spectrum played by the loudspeaker, the detection device can quickly and effectively detect, is high in efficiency and low in cost.

Description

Technical Field

[0001] This invention belongs to the field of loudspeaker technology, specifically relating to an online detection device and method for short-circuit and open-circuit faults in loudspeaker loads based on a Class D power amplifier. Background Technology

[0002] Electric vehicles are rapidly gaining popularity, and people are paying increasing attention to driving comfort and safety. As a key component affecting the driving experience, the in-vehicle audio system is undergoing a comprehensive upgrade. The number of speakers has increased from the traditional four to 8-24. Furthermore, with the increasing number of motors and the growing complexity of thermal and battery management systems in electric vehicles, the number of wiring harnesses inside the vehicle is increasing, creating a complex web that demands higher reliability. Speaker wiring is relatively long, running inside the vehicle. Standard in-vehicle audio systems typically check the speaker status before powering on. Traditional testing methods mainly involve pre-power-on diagnostics, but these methods cannot provide real-time speaker status checks after the system is powered on, nor can they proactively issue fault warnings while driving, impacting safety, especially in scenarios where the in-vehicle audio system is needed for emergency assistance.

[0003] Speaker short-circuit and open-circuit detection essentially involves injecting a specific voltage into the speaker load using an audio power amplifier, then detecting the corresponding current (or injecting a certain current and detecting the voltage across the speaker). The impedance of the speaker is then determined based on the relationship between the voltage and current. Regardless of the method (voltage injection or current injection), the core issue is that a test signal of a specific frequency must be provided. This test signal must not interfere with the sound spectrum (sound content) being played by the speaker, or in other words, it must not fall within the speaker's designed operating frequency range.

[0004] Therefore, there is an urgent need to propose an online detection device and method for short circuit and open circuit of speaker load based on Class D power amplifier. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an online detection device and method for short-circuit and open-circuit faults in speaker loads based on a Class D power amplifier.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] This invention provides an online short-circuit / open-circuit detection device for speaker loads based on a Class D power amplifier, comprising a current acquisition module, a current prediction module, a comparator, and a fault determination module.

[0008] The current acquisition module is used to acquire and record the current of the upper and lower tubes;

[0009] The current prediction module is used to predict the current I based on the input audio signal, the power amplifier system gain, and the speaker impedance. EXPECT Overlay offset;

[0010] The input terminal of the comparator is electrically connected to the output terminals of the current acquisition module and the current prediction module, and is used to compare the acquired upper tube current and lower tube current with the predicted current I after superimposing the offset. EXPECT Compare;

[0011] The input terminal of the fault judgment module is electrically connected to the output terminal of the comparator. It is used to determine whether the speaker load has an open circuit fault or a short circuit fault based on the comparison result of the comparator and the magnitude of the current predicted current value, and to issue a corresponding feedback signal.

[0012] Preferably, the current prediction module includes a bandpass filter, a first multiplier, a second multiplier, a first divider, a second divider, a first adder, and a second adder;

[0013] The input of the bandpass filter is electrically connected to the audio signal of the Class D audio amplifier to obtain a set frequency band range f. L -f H The audio signal inside;

[0014] The input terminals of the first and second multipliers are electrically connected to the output terminal of the bandpass filter, for use in converting the set frequency band range f L -f H The audio signal inside is multiplied by the power amplifier gain G;

[0015] The input of the first divider is electrically connected to the output of the first multiplier, and is used to convert the gained set frequency band range f L -f H The first offset is formed by dividing the audio signal within the frequency band by the maximum impedance of the speaker in that frequency band.

[0016] The input of the second divider is electrically connected to the output of the second multiplier, and is used to convert the gained set frequency band range f L -f H The second offset is formed by dividing the audio signal within the frequency band by the minimum impedance of the speaker in that frequency band.

[0017] The input terminals of the first adder and the second adder are electrically connected to the output terminals of the first divider and the second divider, respectively, for use in predicting the current I. EXPECT The first offset and the second offset are superimposed respectively.

[0018] Preferably, the fault determination module includes a load open-circuit detection module, which is configured to:

[0019] S11. For the upper and lower transistor currents of the Class D audio power amplifier, if within the set counting period 1 / f... L The internal current is always greater than the predicted current I after the first offset is added. EXPECT If so, no open-circuit fault occurs in the speaker load;

[0020] S12. For the upper and lower transistor currents of the Class D audio power amplifier, if within the set counting period 1 / f... L The internal current is always less than the predicted current I after the first offset is added. EXPECT And the predicted current I EXPECT Greater than the set threshold I THR If the speaker load has an open circuit fault, an open circuit alarm will be reported; if it occurs within the set counting period 1 / f L The internal current is always less than the predicted current I after the first offset is added. EXPECT And the predicted current I EXPECT Not exceeding the set threshold I THR If not, the test result is deemed invalid.

[0021] Preferably, the fault determination module includes a load short-circuit detection module, which is configured as follows:

[0022] S21. For the upper and lower transistor currents of the Class D audio power amplifier, if within the set counting period 1 / f... L The internal current is always less than the predicted current I after adding the second offset. EXPECT If so, no short circuit fault occurs in the speaker load;

[0023] S22. For the upper and lower transistor currents of the Class D audio power amplifier, if within the set counting period 1 / f... L The internal current is always greater than the predicted current I after adding the second offset. EXPECT And the predicted current I EXPECT Greater than the set threshold I THR If a short circuit fault occurs in the speaker load, a speaker short circuit alarm will be reported; if it occurs within the set counting period 1 / f L The internal current is always greater than the predicted current I after adding the second offset. EXPECT And the predicted current I EXPECT Less than the set threshold I THR If not, the test result is deemed invalid.

[0024] Preferably, the present invention also provides an online detection method for short-circuit and open-circuit of speaker load based on a Class D power amplifier. The method is applied to the aforementioned online detection device for short-circuit and open-circuit of speaker load based on a Class D power amplifier, and includes the following steps:

[0025] S1. Speaker load open circuit detection: Current sampling is performed on the upper transistor current of OUTP and OUTN of the Class D audio power amplifier, as well as the lower transistor current of OUTP and OUTN, during each PWM cycle; if within a certain counting cycle 1 / f... L The output current of the internal audio Class D power amplifier is always less than the predicted current I. EXPECT Furthermore, the output current of the Class D audio amplifier is greater than the set threshold I. THR If the test result is valid, the horn open-circuit alarm will be reported.

[0026] S2, Speaker Load Short Circuit Detection: Current sampling is performed on the upper and lower transistors (OUTP and OUTN) of the Class D audio amplifier during each PWM cycle; if within a certain counting period 1 / f... L The output current of the internal audio Class D power amplifier is always greater than the predicted current I. EXPECT Furthermore, the output current of the Class D audio amplifier is greater than the set threshold I. THR If the test result is found to be valid, a short-circuit alarm for the horn will be reported.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention compares the collected upper and lower tube currents with the predicted current using a comparator, and then the fault determination module determines the result and sends a corresponding feedback signal. This test does not interfere with the sound spectrum played by the speaker, and the detection device can perform detection quickly and effectively, with high efficiency and low cost. Attached Figure Description

[0029] Figure 1 This is a basic framework diagram of the Class D audio amplifier in this invention;

[0030] Figure 2 This is a schematic diagram of the working principle of the speaker load open circuit detection module in this invention;

[0031] Figure 3 This is a schematic diagram illustrating the working principle of the speaker load short-circuit detection module in this invention. Detailed Implementation

[0032] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0033] This embodiment provides an online short-circuit / open-circuit detection device for a speaker load based on a Class D power amplifier, including a current acquisition module, a current prediction module, a comparator, and a fault decision module. The fault decision module includes an open-circuit detection module and a short-circuit detection module. The internal block diagram of the Class D audio power amplifier is shown below. Figure 1 As shown. The signal processor is responsible for processing the digital audio signal (usually a discrete digital signal sampled from 8kHz to 192kHz), such as bass enhancement, frequency response compensation, amplitude limiting, etc.; the digital-to-analog converter upsamples the processed audio signal to a higher frequency (e.g., 384kHz or 768kHz) for digital-to-analog conversion to obtain an analog audio signal; the gain adjustment module further amplifies the analog audio signal; the modulator modulates the low-frequency audio signal (usually 20Hz to 20kHz) to a higher switching frequency, typically 384kHz to 2.1MHz. The amplitude of the audio signal is reflected in the PWM (Pulse Width Modulation); the larger the audio signal amplitude, the larger the duty cycle of the PWM signal. The output PWM signal of the modulator is sent to the gate driver, which provides a certain current driving capability to create a certain voltage difference between the gate and source of the NMOS transistor, thereby turning the output MOS transistor on or off. MOSFETs switch at high frequencies, with only two transistors on at a time. This can be achieved either by the following patterns: audio current flows from the upper MOSFET of OUTP to the lower MOSFET of OUTN; audio current flows from the upper MOSFET of OUTN to the lower MOSFET of OUTP; audio current flows from the upper MOSFETs of OUTP / OUTN through the upper MOSFETs of OUTN / OUTP and then back to the upper MOSFETs of OUTP / OUTN via PVDD; or audio current flows from the lower MOSFETs of OUTP / OUTN through the lower MOSFETs of OUTN / OUTP and then back to the lower MOSFETs of OUTP / OUTN via GND. The four MOSFETs in a Class D amplifier continuously switch at high frequencies. Each MOSFET completes its switching within several consecutive PWM cycles, and the average current flowing through the speaker (after ripple current filtering) should be equal to the average current of each MOSFET (after ripple current filtering).

[0034] The current acquisition module is used to acquire the current of the upper tube and the current of the lower tube, and record the maximum value within a certain period of time.

[0035] The current prediction module is used to predict the current I based on the input audio signal, the power amplifier system gain, and the speaker impedance. EXPECT Superimposed offset. Specifically, the current prediction module includes a bandpass filter, a first multiplier, a second multiplier, a first divider, a second divider, a first adder, and a second adder; the input of the bandpass filter is electrically connected to the audio signal of the Class D audio amplifier to obtain a set frequency band range f. L -f H The audio signal within the specified frequency band; the input terminals of the first multiplier and the second multiplier are electrically connected to the output terminal of the bandpass filter, used to convert the audio signal within the specified frequency band range f. L -f HThe audio signal within is multiplied by the power amplifier gain G; the input of the first divider is electrically connected to the output of the first multiplier, used to multiply the amplified frequency range f. L -f H The audio signal within the range is divided by the maximum impedance of the speaker in that frequency band to form a first offset; the input of the second divider is electrically connected to the output of the second multiplier, used to adjust the gain of the set frequency band range f. L -f H The audio signal within the frequency band is divided by the minimum impedance of the speaker in that frequency band to form a second offset; the input terminals of the first adder and the second adder are electrically connected to the output terminals of the first divider and the second divider, respectively, for use in predicting the current I. EXPECT The first offset and the second offset are superimposed respectively.

[0036] The input terminal of the comparator is electrically connected to the output terminals of the current acquisition module and the current prediction module, and is used to compare the acquired upper tube current and lower tube current with the predicted current I after superimposing the offset. EXPECT Compare them.

[0037] The input terminal of the fault judgment module is electrically connected to the output terminal of the comparator. It is used to determine whether the speaker load has an open circuit fault, short circuit fault, short circuit to power supply fault, or short circuit to ground fault based on the comparison result of the comparator and the current predicted current, and to issue corresponding feedback signals.

[0038] like Figure 2 As shown, the fault judgment module includes a load open-circuit detection module, which is configured to: S11, detect the upper and lower tube currents of the Class D audio power amplifier, and if the currents are within a set counting period 1 / f... L The internal current is always greater than the predicted current I after the first offset is added. EXPECT If no open-circuit fault occurs in the speaker load, then S12, for the upper and lower tube currents of the Class D audio power amplifier, if within the set counting period 1 / f L The internal current is always less than the predicted current I after the first offset is added. EXPECT And the predicted current I EXPECT Greater than the set threshold I THR If the speaker load has an open circuit fault, an open circuit alarm will be reported; if it occurs within the set counting period 1 / f L The internal current is always less than the predicted current I after the first offset is added. EXPECT And the predicted current I EXPECT Not exceeding the set threshold I THR If not, the test result is deemed invalid.

[0039] like Figure 3As shown, the fault judgment module also includes a load short-circuit detection module, which is configured as follows: S21, for the upper and lower tube currents of the audio Class D power amplifier, if within a set counting period 1 / f... L The internal current is always less than the predicted current I after adding the second offset. EXPECT If no short circuit fault occurs in the speaker load, then S22, for the upper and lower tube currents of the Class D audio power amplifier, if within the set counting period 1 / f L The internal current is always greater than the predicted current I after adding the second offset. EXPECT And the predicted current I EXPECT Greater than the set threshold I THR If a short circuit fault occurs in the speaker load, a speaker short circuit alarm will be reported; if it occurs within the set counting period 1 / f L The internal current is always greater than the predicted current I after adding the second offset. EXPECT And the predicted current I EXPECT Not exceeding the set threshold I THR If not, the test result is deemed invalid.

[0040] In this embodiment, the detection frequency range of each of the load open circuit detection module, load short circuit detection module, load short circuit to power supply detection module, and load short circuit to ground detection module, the maximum impedance of the speaker in the corresponding frequency band, and the preset threshold I are defined. THR and predicted current I EXPECT The offsets are all adjusted according to the actual application conditions.

[0041] This embodiment also provides an online short-circuit / open-circuit detection method for speaker loads based on a Class D power amplifier. The method is applied to the aforementioned online short-circuit / open-circuit detection device for speaker loads based on a Class D power amplifier, and includes the following steps:

[0042] S1. Speaker load open circuit detection: Current sampling is performed on the upper transistor current of OUTP and OUTN of the Class D audio power amplifier, as well as the lower transistor current of OUTP and OUTN, during each PWM cycle; if within a certain counting cycle 1 / f... L The output current of the internal audio Class D power amplifier is always less than the predicted current I. EXPECT Furthermore, the output current of the Class D audio amplifier is greater than the set threshold I. THR If the test result is valid, the horn open-circuit alarm will be reported.

[0043] S2, Speaker Load Short Circuit Detection: Current sampling is performed on the upper and lower transistors (OUTP and OUTN) of the Class D audio amplifier during each PWM cycle; if within a certain counting period 1 / f... L The output current of the internal audio Class D power amplifier is always greater than the predicted current I.EXPECT Furthermore, the output current of the Class D audio amplifier is greater than the set threshold I. THR If the test result is found to be valid, a short-circuit alarm for the horn will be reported.

[0044] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An online short-circuit and open-circuit detection device for speaker loads based on a Class D power amplifier, characterized in that, It includes a current acquisition module, a current prediction module, a comparator, and a fault determination module. The current acquisition module is used to acquire and record the current of the upper and lower tubes; The current prediction module is used to predict the current I based on the input audio signal, the power amplifier system gain, and the speaker impedance. EXPECT The current prediction module includes a bandpass filter, a first multiplier, a second multiplier, a first divider, a second divider, a first adder, and a second adder. The input of the bandpass filter is electrically connected to the audio signal of the Class D audio amplifier to obtain a set frequency band range f. L -f H The audio signal within the specified frequency band; the input terminals of the first multiplier and the second multiplier are electrically connected to the output terminal of the bandpass filter, used to convert the audio signal within the specified frequency band range f. L -f H The audio signal within is multiplied by the power amplifier system gain; the input of the first divider is electrically connected to the output of the first multiplier, used to multiply the gained set frequency band range f. L -f H The audio signal within the range is divided by the maximum impedance of the speaker in that frequency band to form a first offset; the input of the second divider is electrically connected to the output of the second multiplier to convert the gained set frequency band range f L -f H The audio signal within the frequency band is divided by the minimum impedance of the speaker in that frequency band to form a second offset; the input terminals of the first adder and the second adder are electrically connected to the output terminals of the first divider and the second divider, respectively, for use in predicting the current I. EXPECT Superimpose the first offset and the second offset respectively; The input terminal of the comparator is electrically connected to the output terminals of the current acquisition module and the current prediction module. The comparator combines the acquired upper and lower transistor currents with the predicted current I obtained by superimposing the offset. EXPECT Compare them separately; The input terminal of the fault judgment module is electrically connected to the output terminal of the comparator. It is used to determine whether the speaker load has an open circuit fault or a short circuit fault based on the comparison result of the comparator, and to issue a corresponding feedback signal.

2. The online short-circuit and open-circuit detection device for speaker load based on a Class D power amplifier according to claim 1, characterized in that, The fault determination module includes a load open-circuit detection module, which is configured as follows: S11. For the upper and lower transistor currents of the Class D audio power amplifier, if within the set counting period 1 / f... L The internal current is always greater than the predicted current I after the first offset is added. EXPECT If so, no open-circuit fault occurs in the speaker load; S12. For the upper and lower transistor currents of the Class D audio power amplifier, if within the set counting period 1 / f... L The internal current is always less than the predicted current I after the first offset is added. EXPECT And the predicted current I EXPECT Greater than the set threshold I THR If the speaker load has an open circuit fault, an open circuit alarm will be reported; if within the set counting period 1 / f L The internal current is always less than the predicted current I after the first offset is added. EXPECT And the predicted current I EXPECT Not exceeding the set threshold I THR If not, the test result is deemed invalid.

3. The online short-circuit and open-circuit detection device for speaker load based on a Class D power amplifier according to claim 1, characterized in that, The fault determination module further includes a load short-circuit detection module, which is configured as follows: S21. For the upper and lower transistor currents of the Class D audio power amplifier, if within the set counting period 1 / f... L The internal current is always less than the predicted current I after adding the second offset. EXPECT If so, no short circuit fault occurs in the speaker load; S22. For the upper and lower transistor currents of the Class D audio power amplifier, if within the set counting period 1 / f... L The internal current is always greater than the predicted current I after adding the second offset. EXPECT And the predicted current I EXPECT Greater than the set threshold I THR If a short circuit fault occurs in the speaker load, a speaker short circuit alarm will be reported; if it occurs within the set counting period 1 / f L The internal current is always greater than the predicted current I after adding the second offset. EXPECT And the predicted current I EXPECT Not exceeding the set threshold I THR If not, the test result is deemed invalid.

4. A method for online detection of short circuit and open circuit in a speaker load based on a Class D power amplifier, characterized in that, The method is applied to the online short-circuit and open-circuit detection device for speaker load based on a Class D power amplifier as described in claim 1, and the method includes the following steps: S1. Speaker load open circuit detection: Current sampling is performed on the upper transistor current of OUTP and OUTN of the Class D audio power amplifier, as well as the lower transistor current of OUTP and OUTN, during each PWM cycle; if within a certain counting cycle 1 / f... L The upper and lower transistor currents of the internal audio Class D power amplifier are always less than the predicted current I after adding the first offset. EXPECT And the predicted current I EXPECT Greater than the set threshold I THR If the test result is valid, an open-circuit alarm for the loudspeaker will be reported. S2, Speaker Load Short Circuit Detection: Current sampling is performed on the upper and lower transistors (OUTP and OUTN) of the Class D audio amplifier during each PWM cycle; if within a certain counting period 1 / f... L The upper and lower transistor currents of the internal audio Class D power amplifier are always greater than the predicted current I after adding the second offset. EXPECT And the predicted current I EXPECT Greater than the set threshold I THR If the test result is found to be valid, a speaker short-circuit alarm will be reported.

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