A method for judging parallel load fault and a constant voltage power amplifier system

Abstract

The present invention discloses a constant-voltage power amplifier system using a method for judging a parallel load fault, comprising a buffer module, a signal analysis module, a comparison module, a power amplifier module, and a detection module. The detection module detects the input signal and output current of the power amplifier module at the same time, and saves the data in the buffer module. The signal analysis module performs frequency domain analysis on the input signal and output current stored in the buffer module to obtain the measured transconductance Gt of the constant-voltage power amplifier system at the detection moment. The comparison module compares the measured transconductance Gt with the preset transconductance Gs, and sends the judgment result to the detection module. The present invention uses the synchronized input signal and output current data stored in the buffer to ensure the synchronization and correctness of the transconductance data, and avoids data analysis deviations caused by asynchronous input and output; using the change in transconductance to judge the working condition of the parallel load is more accurate and practical than amplitude monitoring; and has a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the field of electronic products, and in particular to a method for judging a parallel load fault and a constant voltage power amplifier system using the method. Background Art

[0002] To minimize losses caused by cable length, public address systems in public spaces often use a constant-voltage system. In this system, a power amplifier outputs a standard voltage, and multiple constant-voltage speakers are connected in parallel as needed to implement the public address function. Because the speakers are connected in parallel, the voltage at the output of the constant-voltage power amplifier remains unchanged if one speaker fails. Therefore, the output voltage cannot be used to determine the load's condition, necessitating output current monitoring. Because excessive current flows when a speaker shorts, the power amplifier's overcurrent protection activates. Therefore, in this case, a speaker failure specifically refers to a short circuit. However, the signals broadcast by speakers are often audio or voice signals, which have time-varying frequency and amplitude. While real-time output current monitoring can detect increases or decreases, it still cannot determine whether the increase or decrease is due to the input signal or a system failure.

[0003] During normal operation of a constant-voltage amplifier system, the system gain remains constant regardless of changes in the input signal. In the aforementioned scenario, the system voltage gain remains unchanged regardless of load damage. However, the input current is too small to detect, making it difficult to determine the current gain and, therefore, to determine whether any individual parallel load is damaged.

[0004] Therefore, in order to determine whether there is a faulty individual in the parallel load of the constant voltage power amplifier, it is necessary to provide a method for determining parallel load faults based on transconductance and a constant voltage power amplifier system using the method. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for determining whether a parallel load has a faulty individual according to a transconductance change, and a constant voltage power amplifier system for system protection using the method.

[0006] In order to solve the above technical problems, the present invention provides a method for determining a parallel load fault, comprising:

[0007] Detect and collect input signals and output currents simultaneously, and save the data in a buffer;

[0008] Performing frequency domain analysis on the input signal and output current stored in the buffer at 1 kHz to obtain a measured transconductance Gt; if the measured transconductance Gt does not exist, performing frequency domain analysis on the input signal and output current stored in the buffer to select a frequency point Fm with the maximum transconductance in the frequency response, and taking the transconductance at Fm as the measured transconductance Gt; when the measured transconductance Gt exists, continuing with the following steps.

[0009] Optionally, the measured transconductance Gt not existing means that the transconductance at 1 kHz is lower than a minimum transconductance limit Gm; wherein the minimum transconductance limit Gm is the product of a minimum signal gain detectable by the system, the inverse of the system impedance, and a maximum allowable error.

[0010] The measured impedance Gt is compared with the preset impedance Gs. If the measured impedance Gt is greater than or equal to the preset impedance Gs, return to the first step and repeat the above steps; if the measured impedance Gt is less than the preset impedance Gs, it is determined that there is an individual fault in the parallel load.

[0011] Optionally, the preset impedance Gs refers to the product of the system's design gain, the inverse of the system impedance, and a maximum allowable error.

[0012] Optionally, returning to the first step and repeating the above steps refers to detecting and collecting the input signal and the output current again simultaneously, and storing the data in a buffer, as well as subsequent steps.

[0013] The present invention also provides a constant-voltage power amplifier system using a method for determining a parallel load fault, comprising a buffer module, a signal analysis module, a comparison module, a power amplifier module, and a detection module. The detection module detects the input signal and output current of the power amplifier module at the same moment, and stores the detected data in the buffer module. The buffer module temporarily stores the data detected by the detection module. The signal analysis module performs frequency domain analysis on the input signal and output current stored in the buffer module to obtain the measured transconductance Gt of the constant-voltage power amplifier system at the moment of detection. The comparison module compares the measured transconductance Gt with the preset transconductance Gs, and sends the comparison result to the detection module.

[0014] The detection module detects the input signal and output current of the power amplifier module at the same time and stores the detected current data in the buffer module. When the comparison module determines that a fault has occurred in an individual of the parallel loads, the detection module is shut down. When the comparison module determines that the constant-voltage power amplifier system is operating normally, the detection module will again detect the input signal and output current of the power amplifier module at the same time and store the detected data in the buffer module. The detection module will not be shut down until the comparison module determines that a fault has occurred in an individual of the parallel loads.

[0015] The buffer module temporarily stores the input signal and output current of the power amplifier module detected by the detection module at the same moment. When the comparison module determines that a fault has occurred in an individual load in parallel, the detection module is shut down, and the buffer module will continue to store the fault input signal and output current data. When the comparison module determines that the constant-voltage power amplifier system is operating normally, the detection module performs input signal and output current detection again, and the buffer module will clear the previously saved input signal and output current data and store new input signal and output current data.

[0016] The signal analysis module performs frequency domain analysis on the input signal and output current stored in the buffer module: first, the transconductance at 1kHz is obtained; if there is no transconductance at 1kHz, a full frequency domain analysis is performed on the input signal and output current stored in the buffer module to select the frequency point Fm with the maximum transconductance in the frequency response, and a frequency domain analysis is performed on the input signal and output current stored in the buffer module at the maximum frequency point Fm, and the measured transconductance at Fm is recorded as Gt; if there is transconductance at 1kHz, the measured transconductance at 1kHz is recorded as Gt. Among them, no transconductance at 1kHz means that the transconductance at 1kHz is lower than the minimum transconductance limit Gm, and the minimum transconductance limit Gm is the product of the minimum signal gain detectable by the system, the inverse of the system impedance, and the maximum allowable error.

[0017] The comparison module compares the measured transconductance Gt with the preset transconductance Gs. If Gt is greater than the preset transconductance Gs, it is determined that there is damage to an individual in the parallel load of the constant-voltage power amplifier system. If Gt is less than or equal to the preset transconductance Gs, it is determined that the constant-voltage power amplifier is operating normally and there is no damage to the parallel load. The preset transconductance Gs is the product of the system's design gain, the inverse of the system impedance, and the maximum allowable error. The judgment result is sent to the detection module.

[0018] The power amplifier module amplifies the input signal, outputs the amplified signal and connects to multiple parallel loads.

[0019] The method for judging a parallel load fault described in the present invention uses the synchronous input signal and output current data stored in the buffer to ensure the synchronization and correctness of the transconductance data, and avoids the data analysis deviation caused by the input and output being out of sync. According to the main application scenarios of the parallel load, the present invention first performs a 1kHz frequency domain analysis on the signal. Considering that a fixed-frequency signal will be used in some applications, the frequency domain analysis is also added to find a suitable transconductance measurement frequency point, which has a wide range of applications. The present invention uses the change of transconductance to judge the working condition of the parallel load, which is more accurate and practical than measuring the amplitude. In the constant-voltage power amplifier system using the method for judging a parallel load fault described in the present invention, the buffer module, signal analysis module and comparison module can be implemented using digital circuits or analog circuits, and are suitable for more applications.

[0020] In order to make the above contents of the present invention more clearly understood, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a flow chart of a method for determining a parallel load fault according to the present invention;

[0023] Figure 2 A block diagram of a constant voltage power amplifier system using a parallel load fault determination method according to the present invention;

[0024] Figure 3 This is an embodiment of a constant voltage power amplifier system using a parallel load fault determination method according to the present invention;

[0025] Figure 4 This is another embodiment of the constant voltage power amplifier system using the parallel load fault judgment method of the present invention;

[0026] Numbers in the figure:

[0027] 10: detection module; 20: buffer module; 30: signal analysis module;

[0028] 40: comparison module; 50: power amplifier module; 101: current transformer;

[0029] 60: signal processing unit; 3011: finite number of narrowband filter combinations;

[0030] 3012: finite narrowband filter combination 2; 3021: peak comparator 1;

[0031] 3022: Peak comparator 2; 40': Comparison module; 401: K value amplifier;

[0032] 402: Hysteresis comparator. DETAILED DESCRIPTION

[0033] To make the purposes, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in a variety of different configurations. Therefore, the detailed description of the embodiments of the present invention provided in the drawings below is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0034] See also Figure 1 , which is a flow chart of a method for determining a parallel load fault according to the present invention. First, step S1: simultaneously detecting and collecting the input signal and output current of the system. Next, step S2: saving the collected input signal and output current data in a buffer. Then, step S3: performing frequency domain analysis on the input signal and output current of the system at 1kHz to obtain the measured impedance Gt. When Gt does not exist, step S3.1 is performed: performing frequency domain analysis on the input signal and output current, selecting the frequency point Fm with the largest transconductance in the frequency response, and taking the transconductance at Fm as the measured transconductance Gt; when Gt exists, step S4 is performed. Step S4 is: comparing the measured impedance Gt with the preset impedance Gs. When Gt is greater than or equal to Gs, it is determined that the system is working normally, and returning to step S1 to continue monitoring the system; when Gt is less than Gs, it is concluded that an individual fault has occurred in the parallel load.

[0035] See also Figure 2, which is a block diagram of a constant-voltage power amplifier system using a parallel load fault judgment method according to the present invention. It includes a buffer module 20, a signal analysis module 30, a comparison module 40, a power amplifier module 50, and a detection module 10. The detection module 10 detects the input signal and output current of the power amplifier module 50 at the same time, and saves the detected data in the buffer module 20. The buffer module 20 temporarily saves the data detected by the detection module 10. The signal analysis module 30 performs frequency domain analysis on the input signal and output current saved by the buffer module 20 to obtain the measured transconductance Gt of the constant-voltage power amplifier system at the detection moment. The comparison module 40 is used to compare the measured transconductance Gt with the preset transconductance Gs, and send the judgment result to the detection module 10.

[0036] See also Figure 3 This is an embodiment of a constant-voltage power amplifier system using a parallel load fault detection method described in the present invention. The detection module detects the output current using a current transformer 101. The signal processing unit 60 includes a buffer module, a signal analysis module, and a comparison module. The detection module also detects the input signal and processes the input signal Vin and the output signal of the current transformer 101. In this embodiment, the signal processing unit 60 is a digital signal processor that performs data acquisition, temporary storage, frequency domain analysis, and data comparison through instructions within the processor.

[0037] See also Figure 4 , is another embodiment of the constant voltage power amplifier system using the method for determining parallel load faults of the present invention. Figure 3The difference is that the buffer module, signal analysis module, and comparison module in this embodiment are all implemented using analog circuits. The real-time performance of analog circuits ensures the synchronization of input and output signals, so the buffer module can be ignored in this embodiment. If the use of different analog circuits causes a delay between input and output, the buffer circuit here is used to compensate for the delay and ensure input and output synchronization. In this embodiment, the detection module detects the output current using a current transformer 101; the signal analysis module includes a finite number of narrowband filter combinations 1 3011 and a finite number of narrowband filter combinations 2 3012, peak comparator 1 3021 and peak comparator 2 3022, and also includes several logic circuits; the comparison module 40' includes a K value amplifier 401 and a hysteresis comparator 402. A finite number of narrowband filter combinations 1 3011 and a finite number of narrowband filter combinations 2 3012 divide the input signal and the output current signal into a finite number of groups, each of which must include a narrowband filter with a center frequency of 1 kHz. Peak comparator 1 3021 and peak comparator 2 3022 compare the input signal and the output current signal to determine the group with the largest amplitude. Several logic circuits are used to adjust the signal analysis at 1 kHz and the order of signal analysis within all narrowband filter combinations. The group of input signals with the largest amplitude, or signals with a center frequency of 1 kHz, is connected to a K-value amplifier 401, where K is the set gain of the power amplifier system divided by the preset impedance. A hysteresis comparator 402 compares the amplified group of input signals with the largest amplitude, or signals with a center frequency of 1 kHz, with the group of output current signals with the largest amplitude, or signals with a center frequency of 1 kHz. If the former is greater than the latter, it is determined that a faulty individual is present in the parallel load.

[0038] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structures or equivalent process changes made using the contents of the present invention's description and drawings, or directly or indirectly applied to other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for determining a parallel load fault, characterized in that: The following steps are involved: S1-Simultaneously detects and collects input signals and output currents; S2-saves the collected input signal and output current data in the buffer; S3- Perform frequency domain analysis on the input signal and output current stored in the buffer at 1kHz to obtain the measured transconductance Gt. When the measured transconductance Gt is higher than the minimum transconductance limit Gm, proceed to step S4. When the measured transconductance Gt is lower than the minimum transconductance limit Gm, proceed to step S3.

1. The minimum transconductance limit Gm is the product of the minimum signal gain detectable by the system, the inverse of the system impedance, and the maximum allowable error. S3.1- Perform frequency domain analysis on the input signal and output current stored in the buffer to select the frequency point Fm with the maximum transconductance in the frequency response, and take the transconductance at Fm as the measured transconductance Gt; S4-Compare the measured transconductance Gt with the preset transconductance Gs; The preset transconductance Gs refers to the product of the system's design gain, the inverse of the system impedance, and the maximum allowable error; S4.1-If the measured transconductance Gt is greater than or equal to the preset transconductance Gs, return to step S1; S4.2-If the measured transconductance Gt is less than the preset transconductance Gs, it is determined that there is an individual fault in the parallel load.

2. A constant voltage power amplifier system using the parallel load fault judgment method according to claim 1, characterized in that: The system comprises a buffer module, a signal analysis module, a comparison module, a power amplifier module, and a detection module; the detection module detects the input signal and output current of the power amplifier module at the same time, and stores the detected input signal and output current data in the buffer module; the buffer module temporarily stores the data detected by the detection module; the signal analysis module performs frequency domain analysis on the data stored in the buffer module to obtain the measured transconductance Gt of the constant voltage power amplifier system at the detection time; the comparison module compares the measured transconductance Gt with the preset transconductance Gs, and sends the comparison result to the detection module; The detection module is shut down when the comparison module determines that a fault occurs in an individual of the parallel loads; When the comparison module determines that the constant voltage power amplifier system is operating normally, the detection module will again detect the input signal and output current of the power amplifier module at the same time, and save the detected data in the buffer module until the comparison module determines that an individual parallel load has a fault and is shut down; When the comparison module determines that a fault occurs in an individual of the parallel loads, the detection module is turned off, and the buffer module will continue to store the input signal and output current data of the fault; when the comparison module determines that the constant voltage power amplifier system is operating normally, the detection module performs input signal and output current detection again, and the buffer module will clear the input signal and output current data saved last time and save new input signal and output current data; The signal analysis module performs frequency domain analysis on the input signal and output current stored in the buffer module: first, the transconductance at 1 kHz is obtained; if there is no transconductance at 1 kHz, a full frequency domain analysis is performed on the input signal and output current stored in the buffer module to select the frequency point Fm with the maximum transconductance in the frequency response, and a frequency domain analysis is performed on the input signal and output current stored in the buffer module at the maximum frequency point Fm, and the measured transconductance at Fm is recorded as Gt; if there is a transconductance at 1 kHz, the measured transconductance at 1 kHz is recorded as Gt; wherein, no transconductance at 1 kHz means that the transconductance at 1 kHz is lower than a minimum transconductance limit Gm, and the minimum transconductance limit Gm is the product of the minimum signal gain detectable by the system, the inverse of the system impedance, and the maximum allowable error; The comparison module compares the measured transconductance Gt with the preset transconductance Gs. If Gt is greater than the preset transconductance Gs, it is determined that there is individual damage in the parallel load of the constant-voltage power amplifier system; if Gt is less than or equal to the preset transconductance Gs, it is determined that the constant-voltage power amplifier is operating normally and there is no damage in the parallel load. The preset transconductance Gs refers to the product of the design gain of the system, the inverse of the system impedance and the maximum allowable error. The judgment result is sent to the detection module; The power amplifier module amplifies the input signal, outputs the amplified signal and connects to multiple parallel loads.

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