A voltage identification switching method and device for an adaptive sound system

Abstract

The application relates to the technical field of sound systems, and discloses a voltage identification and switching method and device for an adaptive sound system. The method comprises the following steps: resistance voltage division and rectification filtering are performed on an alternating-current input voltage to obtain a first direct-current level; when the first direct-current level is located in a first threshold interval, the first direct-current level is determined as a first voltage mode; when the first direct-current level is located in a second threshold interval, the first direct-current level is determined as a second voltage mode; a normally closed contact or a normally open contact in a relay is controlled to be closed; an alternating-current output voltage is generated according to the alternating-current input voltage; resistance voltage division and rectification filtering are performed on the alternating-current output voltage to obtain a second direct-current level; and the tap position and the effective number of turns of a second winding in a step-down transformer are adjusted according to the second direct-current level. The application ensures that the output voltage remains stable under the conditions of input voltage fluctuation and load change, and meets the strict requirements of sound equipment on power supply quality.

Description

Technical Field

[0001] This invention relates to the field of audio system technology, and in particular to a voltage identification and switching method and apparatus for an adaptive audio system. Background Technology

[0002] Audio equipment needs to adapt to different local voltage standards. Because voltage standards vary, some areas use 110V power while others use 220V. Current audio products use manual voltage selection switches to adapt to different voltages; users need to select the appropriate setting based on their local power grid voltage standard before use.

[0003] Existing technology makes it easy for users to forget to adjust the voltage setting when changing locations, leading to a mismatch between the input voltage and the device's rated operating voltage. This can cause malfunctions such as overcurrent in the rectifier circuit, breakdown of the filter capacitor, and damage to the power amplifier circuit, and in severe cases, short circuits and fires. The mechanical contacts of manual switches are prone to oxidation and poor contact after long-term use, affecting the reliability of voltage switching. If users do not check the local voltage standard when purchasing products and directly plug in the wrong setting, it can cause permanent damage to power devices. Summary of the Invention

[0004] The main objective of this invention is to provide a voltage identification and switching method and apparatus for an adaptive audio system. This invention ensures that the output voltage remains stable under conditions of input voltage fluctuations and load changes, thus meeting the stringent power supply quality requirements of audio equipment.

[0005] To achieve the above objectives, the present invention provides a voltage identification and switching method for an adaptive audio system, comprising the following steps: The AC input voltage is divided by resistors and rectified and filtered to obtain the first DC level. When the first DC level is within the first threshold range, it is determined to be the first voltage mode; when the first DC level is within the second threshold range, it is determined to be the second voltage mode. The normally closed or normally open contacts in the control relay are closed according to the first voltage mode or the second voltage mode. When the normally closed contact is closed, the AC input voltage generates an AC output voltage through a direct path; when the normally open contact is closed, the AC input voltage generates an AC output voltage through the first and second windings of the step-down transformer. The AC output voltage is divided by resistors and rectified and filtered to obtain a second DC level. The tap position and effective number of turns of the second winding in the step-down transformer are adjusted according to the second DC level.

[0006] Optionally, in a first implementation of the first aspect of the present invention, the AC input voltage is subjected to resistor voltage division and rectification filtering to obtain a first DC level, including: The AC input voltage is divided by connecting the first voltage divider resistor and the second voltage divider resistor in series, and the AC sampling voltage is obtained at the connection node of the first voltage divider resistor and the second voltage divider resistor. The AC sampling voltage is input into the first rectifier circuit for full-wave rectification to obtain the first pulsating DC voltage. The first pulsating DC voltage is smoothed and filtered by the first filter circuit to obtain the first DC level.

[0007] Optionally, in a second implementation of the first aspect of the present invention, the AC sampling voltage is input to a first rectifier circuit for full-wave rectification to obtain a first pulsating DC voltage, including: The AC sampling voltage is connected to the first AC input terminal of the first rectifier circuit via a current-limiting resistor; When the AC sampling voltage is in the positive half-cycle, the first rectifier diode and the second rectifier diode arranged diagonally in the first rectifier circuit are turned on, generating a first positive voltage at the first DC output terminal of the first rectifier circuit. When the AC sampling voltage is in the negative half-cycle, the third and fourth rectifier diodes arranged diagonally in the first rectifier circuit are turned on, generating a second positive voltage at the first DC output terminal of the first rectifier circuit. The first positive voltage and the second positive voltage are combined to form a first pulsating DC voltage.

[0008] Optionally, in a third implementation of the first aspect of the present invention, when the first DC level is within a first threshold range, it is determined to be a first voltage mode; when the first DC level is within a second threshold range, it is determined to be a second voltage mode, including: The first DC level input analog-to-digital converter is sampled multiple times to obtain sampled data, and the average sampled value is calculated based on the sampled data. When the average sampled value is within the first threshold range, it is determined to be the first voltage mode; When the average sampled value is within the second threshold range, it is determined to be the second voltage mode.

[0009] Optionally, in a fourth implementation of the first aspect of the present invention, controlling the closing of normally closed or normally open contacts in the relay according to the first voltage mode or the second voltage mode includes: When the first voltage mode is determined, the microcontroller outputs a low-level signal to turn off the driving transistor. When the driving transistor is turned off, the control relay coil is de-energized to keep the normally closed contact closed. When the second voltage mode is determined, the microcontroller outputs a high-level signal to drive the transistor to conduct through the base current-limiting resistor. When the transistor is driven to conduct, the coil loop current formed between the collector and emitter causes the normally open contact to close.

[0010] Optionally, in a fifth implementation of the first aspect of the present invention, when the normally closed contact is closed, the AC input voltage generates an AC output voltage through a direct-through path; when the normally open contact is closed, the AC input voltage generates an AC output voltage through the first and second windings of a step-down transformer, including: When the normally closed contact is closed, the AC input voltage is directly connected to the output terminal through the normally closed contact to form a straight path, generating an AC output voltage that is the same as the AC input voltage; When the normally open contact is closed, the AC input voltage is applied to the first winding of the step-down transformer through the normally open contact. The first winding generates alternating magnetic flux in the iron core, and the second winding reduces the voltage according to the turns ratio through electromagnetic induction and outputs AC output voltage.

[0011] Optionally, in a sixth implementation of the first aspect of the present invention, the AC output voltage is subjected to resistive voltage division and rectification filtering to obtain a second DC level, and the tap position and effective number of turns of the second winding in the step-down transformer are adjusted according to the second DC level, including: The AC output voltage is divided by the series connection of the third and fourth voltage divider resistors, and the output sampling voltage is obtained at the connection node of the third and fourth voltage divider resistors. The output sampling voltage is input into the second rectifier circuit for full-wave rectification to obtain the second pulsating DC voltage. The second pulsating DC voltage is filtered by the second filter circuit to obtain the second DC level; Adjust the tap position and effective number of turns of the second winding in the step-down transformer according to the second DC level and the preset reference voltage.

[0012] Optionally, in a seventh implementation of the first aspect of the present invention, the output sampling voltage is input into a second rectifier circuit for full-wave rectification to obtain a second pulsating DC voltage, including: Connect the output sampling voltage to the second AC input terminal of the second rectifier circuit; When the output sampling voltage is in the positive half-cycle, the fifth and sixth rectifier diodes arranged diagonally in the second rectifier circuit are turned on, generating a third positive voltage at the second DC output terminal of the second rectifier circuit; When the output sampling voltage is in the negative half-cycle, the seventh and eighth rectifier diodes arranged diagonally in the second rectifier circuit are turned on, generating a fourth positive voltage at the second DC output terminal of the second rectifier circuit; The third positive voltage and the fourth positive voltage are combined to form a second pulsating DC voltage.

[0013] Optionally, in an eighth implementation of the first aspect of the present invention, adjusting the tap position and effective number of turns of the second winding in the step-down transformer according to the second DC level and a preset reference voltage includes: The voltage deviation value is calculated based on the second DC level and the preset reference voltage; When the voltage deviation exceeds a preset deviation threshold, the microcontroller generates a tap adjustment command; The microcontroller sends the tap adjustment command to the tap switching control chip, which drives the tap relay on the second winding to switch to different tap positions, thereby changing the effective number of turns of the second winding.

[0014] The present invention also provides a voltage identification switching device for an adaptive audio system, comprising: The filtering module is used to perform resistive voltage division and rectification filtering on the AC input voltage to obtain the first DC level; A voltage mode determination module is used to determine a first voltage mode when the first DC level is within a first threshold range, and to determine a second voltage mode when the first DC level is within a second threshold range. A contact closing module is used to control the normally closed or normally open contacts in a relay to close according to the first voltage mode or the second voltage mode. An AC output module is used to generate an AC output voltage from the AC input voltage through a direct path when the normally closed contact is closed, and to generate an AC output voltage from the AC input voltage through the first and second windings of a step-down transformer when the normally open contact is closed. The adjustment module is used to perform resistive voltage division and rectification filtering on the AC output voltage to obtain a second DC level, and adjust the tap position and effective number of turns of the second winding in the step-down transformer according to the second DC level.

[0015] In summary, this invention uses a resistor divider and rectifier filter circuit to sample the AC input voltage in real time upon power-up and convert it into a first DC level. This avoids the risk of erroneous voltage impacting the internal circuitry. The first DC level is accurately identified: when the DC level is within a first threshold range, it is determined to be the first voltage mode corresponding to 110V input; when it is within a second threshold range, it is determined to be the second voltage mode corresponding to 220V input. By setting a clear discrimination window, it effectively addresses grid voltage fluctuations and differences in standards, improving the accuracy and reliability of voltage identification. Based on the identification result, the normally closed or normally open contacts of the relay are automatically closed. In the first voltage mode, a direct path is established through the normally closed contacts to achieve efficient transmission from 110V input to 110V output. In the second voltage mode, the normally open contacts connect the first and second windings of the step-down transformer to achieve precise voltage reduction from 220V to 110V. This dual-mode circuit topology adaptive switching mechanism completely eliminates the need for a manual voltage selection switch, preventing equipment damage caused by users forgetting to switch or misoperation, thus improving the product's intelligence and user safety. Meanwhile, a second DC level is obtained by resistive voltage division and rectification filtering of the AC output voltage. The tap position and effective number of turns of the second winding of the step-down transformer are dynamically adjusted according to the deviation between the second DC level and the preset reference voltage to ensure that the output voltage remains stable under the condition of input voltage fluctuation and load change, thus meeting the strict power supply quality requirements of audio equipment. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the voltage identification and switching method steps of an adaptive audio system in one embodiment of the present invention; Figure 2 This is a diagram of the adaptive voltage identification and switching main circuit in an embodiment of the present invention; Figure 3 This is a circuit diagram of the auxiliary power supply DC-DC conversion circuit in an embodiment of the present invention; Figure 4 This is a circuit diagram of the controller and communication interface in an embodiment of the present invention; Figure 5 This is a structural block diagram of the voltage identification and switching device of the adaptive audio system in an embodiment of the present invention.

[0017] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] Reference Figure 1 This embodiment provides a voltage identification and switching method for an adaptive audio system, including the following steps: S1 performs resistor voltage division and rectification filtering on the AC input voltage to obtain the first DC level; S2, when the first DC level is within the first threshold range, it is determined to be the first voltage mode; when the first DC level is within the second threshold range, it is determined to be the second voltage mode. S3 controls the normally closed or normally open contacts in the relay to close according to the first voltage mode or the second voltage mode; S4, when the normally closed contact is closed, the AC input voltage generates the AC output voltage through the direct path; when the normally open contact is closed, the AC input voltage generates the AC output voltage through the first and second windings of the step-down transformer. S5 performs resistor voltage division and rectification filtering on the AC output voltage to obtain the second DC level, and adjusts the tap position and effective number of turns of the second winding in the step-down transformer according to the second DC level.

[0020] Figure 2 This is the main circuit diagram for voltage identification switching in an adaptive audio system. It includes an AC 110V~220V input terminal. The AC input voltage is split into two paths after passing through an EMI filter circuit: the first path samples the voltage through a resistor divider network and a bridge rectifier circuit to obtain a first DC level signal for voltage identification; the second path serves as the main power path and is sent to the relay switching circuit. Relay K1 switches between normally closed and normally open contacts according to the microcontroller's control signal: when the normally closed contact is closed, the AC input voltage is directly output to the AC 110V output terminal via a direct path; when the normally open contact is closed, the AC input voltage is stepped down by a 2:1 ratio through the first and second windings of the step-down transformer T1 before being output to the AC 110V output terminal. It also includes a relay drive circuit, composed of a drive transistor, a base current-limiting resistor, and a freewheeling diode, used to control the on / off state of the relay coil. The output terminal is equipped with a resistor divider and rectifier filter circuit to sample the output voltage and generate a second DC level feedback signal.

[0021] Figure 3This is a circuit diagram for an auxiliary power supply DC-DC converter. It converts a 24V DC input voltage to a 5V DC output voltage to power microcontrollers, sensors, and other control circuits. The circuit includes a DC-DC buck converter chip. Input capacitors C11 and C12 are configured to suppress input ripple, while the output is equipped with an inductor L and an output filter capacitor C13 to smooth the output voltage. The SW pin of the converter chip outputs a switching pulse signal, which, through the cooperation of an inductor and a freewheeling diode, achieves the buck function. The FB pin is connected to a resistor divider network for output voltage feedback regulation, ensuring a stable 5V output voltage. This auxiliary power supply circuit provides a stable and reliable operating power supply for the control section of the entire adaptive voltage identification and switching system.

[0022] Figure 4 This is a circuit diagram of the microcontroller and communication interface. It includes the microcontroller chip, responsible for voltage sampling, data processing, voltage mode discrimination, and relay drive control. Multiple GPIO pins of the microcontroller are connected as follows: pins P14 / P15 / P16 / P17 connect to the voltage sampling ADC input channel to receive the first and second DC level signals; pins P13 / P12 / P11 / P10 connect to the relay drive output channel and status feedback input channel; pins P25 / P24 / P23 connect to the I2C bus (SDA / SCL) for communication with the tap switching control chip. CM4 is the debugging interface for program download and debugging; the UART interface is used for communication with the host computer to implement parameter configuration and historical data reading functions. The microcontroller is powered by a 5V power supply and equipped with decoupling capacitors to ensure stable operation. This circuit is the control core of adaptive voltage recognition and switching, realizing fully automatic intelligent control from voltage sampling to mode switching.

[0023] Specifically, after the relay contacts close and generate an AC output voltage, a stability observation timer is started and continuously monitors the AC input voltage and AC output voltage within the observation time window. When the fluctuation amplitude of the AC input voltage is less than a preset input fluctuation threshold and the fluctuation amplitude of the AC output voltage is less than a preset output fluctuation threshold, a working mode lock flag is set. After the working mode lock flag is set, when the AC input voltage is detected to momentarily deviate from the normal operating range corresponding to the current voltage mode but the duration of the deviation is less than a preset time threshold, the current relay contact state remains unchanged. Only when the AC input voltage continuously deviates from the normal operating range corresponding to the current voltage mode and the duration of the deviation exceeds the preset time threshold, the working mode lock flag is released and the voltage mode discrimination and relay contact switching are re-executed.

[0024] In one example, the AC input voltage is divided by resistors and rectified to obtain a first DC level, including: The AC input voltage is divided by the series connection of the first voltage divider resistor and the second voltage divider resistor, and the AC sampling voltage is obtained at the connection node of the first voltage divider resistor and the second voltage divider resistor. The AC sampling voltage is input into the first rectifier circuit for full-wave rectification to obtain the first pulsating DC voltage; The first pulsating DC voltage is smoothed and filtered by the first filter circuit to obtain the first DC level.

[0025] In this example, the AC input voltage is 110V or 220V industrial frequency AC. A high-impedance resistor divider network is used for linear voltage reduction to obtain a low-voltage sampling signal. The first and second voltage divider resistors are connected in series between the AC input terminal and ground. The first voltage divider resistor is connected to the live wire of the AC output after EMI filtering, and the second voltage divider resistor is grounded, forming a continuous and stable resistor divider chain. At the intermediate connection point between the first and second voltage divider resistors, i.e., the voltage divider point, an AC sampling voltage signal is obtained whose amplitude varies synchronously with the input voltage and is determined by the voltage division ratio. Electrically, the AC sampling voltage signal is still a low-amplitude AC waveform with alternating positive and negative values, and its amplitude is controlled between 1V and 2V. The AC sampling voltage signal is input into the first rectifier circuit, which employs a bridge full-wave rectifier circuit composed of four fast recovery diodes. Its structure involves the input terminals connected to opposite diagonal points, and the output terminals taken from the other two diagonal positions. This ensures that regardless of whether the input voltage is in the forward or reverse conduction cycle, the output terminal can output a unidirectional pulsating voltage of the same polarity, with a pulsating frequency twice the original AC frequency; that is, a 100Hz pulsating DC output under a 50Hz AC input condition. The first pulsating DC voltage has a fixed direction, but its amplitude fluctuates periodically with time. The first pulsating DC signal is smoothed by a first filter circuit, which is an RC low-pass filter network. A typical structure consists of a series current-limiting resistor and a parallel energy storage capacitor. Its working principle is that the capacitor stores energy when the pulsating voltage rises and releases energy during the voltage drop phase to suppress voltage sags, thus forming an approximately constant DC level. The amplitude of the first DC level directly reflects the effective value of the AC input voltage. The first DC level is obtained by selecting the voltage divider ratio, the conduction characteristics of the rectifier devices, and matching the RC parameters.

[0026] In one example, the AC sampling voltage is input to the first rectifier circuit for full-wave rectification to obtain a first pulsating DC voltage, including: The AC sampling voltage is connected to the first AC input terminal of the first rectifier circuit via a current-limiting resistor; When the AC sampling voltage is in the positive half-cycle, the first rectifier diode and the second rectifier diode arranged diagonally in the first rectifier circuit are turned on, generating a first positive voltage at the first DC output terminal of the first rectifier circuit. When the AC sampling voltage is in the negative half-cycle, the third and fourth rectifier diodes arranged diagonally in the first rectifier circuit are turned on, generating a second positive voltage at the first DC output terminal of the first rectifier circuit. The first positive voltage and the second positive voltage are combined to form the first pulsating DC voltage.

[0027] In this example, a bridge full-wave rectifier circuit is used as the core structure. The bridge full-wave rectifier circuit consists of four rectifier diodes forming a closed-loop channel. The first and second rectifier diodes are located at one end of the diagonal, and the third and fourth rectifier diodes are located at the other diagonal. The two terminals of the AC input are connected to the two diagonal input terminals of the bridge circuit. One of the input terminals is connected to a low-voltage AC signal from the AC sampling network through a current-limiting resistor, thereby limiting the current entering the rectifier circuit and improving the safety and response accuracy of the rectifier device. When the AC sampling voltage is in the positive half-cycle, i.e., the voltage is rising, the current path forms a closed circuit through the first and second rectifier diodes. These two diodes are forward biased and conduct, resulting in a positive voltage output at the DC output of the rectifier circuit, i.e., the first positive voltage. When the AC sampling voltage is in the negative half-cycle, i.e., the voltage is changing in the reverse direction, the first and second diodes, which were originally forward biased, are cut off due to reverse bias. At this time, the third and fourth rectifier diodes conduct, and the current path flows through the rectifier bridge in the opposite direction, but the output still maintains a positive voltage of the same polarity, i.e., the second positive voltage. Since the voltage directions of the two half-cycles are the same, the first and second positive voltages are automatically combined at the DC output of the rectifier bridge into a continuous but pulsating unipolar voltage waveform, i.e., the first pulsating DC voltage. Its frequency is twice the frequency of the original AC signal, and its amplitude varies with the amplitude of the input sampling voltage, forming the basic DC signal source.

[0028] In one example, when the first DC level is within a first threshold range, it is determined to be a first voltage mode; when the first DC level is within a second threshold range, it is determined to be a second voltage mode, including: The first DC level input analog-to-digital converter is sampled multiple times to obtain sampled data, and the average sampled value is calculated based on the sampled data. When the average sampled value is within the first threshold range, it is determined to be the first voltage mode; When the average sampled value is within the second threshold range, it is determined to be the second voltage mode.

[0029] In this example, the first DC level is connected to the input channel of the analog-to-digital converter (ADC) inside the microcontroller. The ADC module is configured for continuous sampling mode, with a sampling frequency set to the tens of kilohertz level, such as 50 kHz. Simultaneously, to improve the stability of ADC sampling, DMA (Direct Memory Access) is enabled, directly writing each sampling result to an internal buffer array to avoid data interruptions caused by main program response delays. During the power-on initialization phase, the MCU starts the ADC and performs warm-up sampling, followed by a predetermined number of continuous samples, for example, acquiring 256 sampling points. The sampling results are sequentially stored in an array structure named `sample_buffer`. After sampling, the MCU performs a simple sorting of the sampled values ​​in the array, removing several maximum and minimum values ​​to eliminate the influence of quantization errors or spike interference, and performs an arithmetic average operation on the remaining values ​​to obtain the average sampled value, reflecting the true amplitude of the input voltage. The MCU compares the average sampled value with a preset voltage mode discrimination threshold. The first threshold range is set to reflect the level range corresponding to the 110V voltage input, such as 0.8V to 1.3V. If the average sampled value is within this range, the current voltage is determined to be the first voltage mode. The second threshold range is set to the level range corresponding to the 220V voltage input, such as 1.8V to 2.3V. If the average sampled value falls into this range, it is determined to be the second voltage mode.

[0030] The first DC level is input to the analog-to-digital converter for multiple consecutive samplings to obtain sampled data, including: within a preset time window after the AC input voltage is turned on, starting the analog-to-digital converter to continuously sample the first DC level at a preset sampling frequency, and automatically transferring the sampling results to the sampling buffer through the direct memory access controller; sorting the sampling results in the sampling buffer, removing the maximum value group and the minimum value group to obtain the valid sampled data; and performing an arithmetic mean operation on the valid sampled data to obtain the average sampled value.

[0031] When the average sampled value is within the gray threshold interval, the gray threshold interval is between the upper limit of the first threshold interval and the lower limit of the second threshold interval; start the delay timer and after the delay ends, continuously sample the first DC level to obtain the second sampled data, and calculate the second average sampled value based on the second sampled data; compare the changing trends of the average sampled value and the second average sampled value, and determine the second voltage mode when the second average sampled value is greater than the average sampled value and tends to the second threshold interval, and determine the first voltage mode when the second average sampled value is less than the average sampled value and tends to the first threshold interval.

[0032] In one example, controlling the closing of normally closed or normally open contacts in a relay according to a first voltage mode or a second voltage mode includes: When the first voltage mode is determined, the microcontroller outputs a low-level signal to turn off the driving transistor. When the driving transistor is turned off, the control relay coil is de-energized to keep the normally closed contact closed. When the second voltage mode is determined, the microcontroller outputs a high-level signal to drive the transistor to conduct through the base current-limiting resistor. When the transistor is driven to conduct, the coil loop current formed between the collector and emitter causes the normally open contact to close.

[0033] In this example, a voltage-mode actuator is used, employing an NPN transistor as the switching controller, a microcontroller GPIO as the drive signal source, and a relay as the output path switching element. The digital output pin of the microcontroller is connected to the base of the transistor, with a base-limiting current resistor in series. This resistor limits the microcontroller's output current, preventing overcurrent damage to the pin or the transistor's base structure. The transistor's emitter is grounded, and its collector is connected to one end of the relay coil. The other end of the coil is connected to an auxiliary power supply (e.g., +12V), forming the main control point of the current path. Simultaneously, to prevent high-voltage reverse induction damage caused by the release of inductor energy in the coil during transistor turn-off, a reverse clamping diode is connected in parallel across the relay coil. Its cathode is connected to the power supply, and its anode is connected to the transistor's collector, forming a freewheeling path. When the microcontroller completes the ADC sampling and discrimination of the input voltage and the identification result is the first voltage mode (e.g., corresponding to 110V input), its GPIO control pin outputs a logic low level (0V). At this time, the base of the driving transistor has no bias voltage and cannot establish a base-emitter current path, so the transistor is in the cut-off state. Since the transistor is cut off, its collector is effectively disconnected, and the relay coil cannot form a closed loop current. The coil is in the de-energized state. At this time, the relay maintains the factory default state, that is, the normally closed contact is closed and the normally open contact is open, thereby establishing a voltage path in the direct-through mode, so that the input AC voltage is directly transmitted to the output terminal through the normally closed contact. This is suitable for 110V input without transformer processing. When the microcontroller identifies the second voltage mode (e.g., corresponding to 220V input), its control pin outputs a high level (e.g., 3.3V or 5V). This high level provides a small current injection to the base of the driving transistor via the base-limiting current resistor. Since a forward bias is established between the base and emitter at this time, the driving transistor is triggered into the conducting state, and its collector voltage is pulled down to near ground potential. A voltage difference between +12V and 0V is formed across the relay coil, generating a stable coil excitation current. After the coil is energized, the change in the internal magnetic field drives the mechanical structure to switch the relay from the default state to the operating state, i.e., the normally closed contact opens and the normally open contact closes. This disconnects the direct path and establishes a voltage transmission structure via the transformer's step-down path, realizing the conversion path from 220V input to 110V output.

[0034] After the microcontroller outputs a drive signal, the actual operating status signal of the relay is read through the relay's auxiliary contacts. The drive signal output by the microcontroller is compared with the actual operating status signal of the relay. If the drive signal is high but the actual operating status signal is low, or if the drive signal is low but the actual operating status signal is high, a relay failure is determined. When a relay failure is determined, the microcontroller stops the system and writes the fault code into the non-volatile memory, while simultaneously driving the fault indicator device to output a fault indication signal.

[0035] In one example, when the normally closed contact is closed, the AC input voltage generates the AC output voltage through a direct path; when the normally open contact is closed, the AC input voltage generates the AC output voltage through the first and second windings of the step-down transformer, including: When the normally closed contact is closed, the AC input voltage is directly connected to the output terminal through the normally closed contact to form a straight path, generating an AC output voltage that is the same as the AC input voltage. When the normally open contact is closed, the AC input voltage is applied to the first winding of the step-down transformer through the normally open contact. The first winding generates alternating magnetic flux in the iron core. The second winding reduces the voltage according to the turns ratio through electromagnetic induction and outputs the AC output voltage.

[0036] In this example, when the input is detected as the first voltage mode (e.g., 110V input), the microcontroller outputs a low-level control signal, de-energizing the relay coil. The relay remains initially stationary, with its normally closed contacts closed and normally open contacts open. The AC input voltage, after being output by the EMI filter module, is directly connected to the system's AC output via the normally closed contacts, without any step-up or step-down processing, forming a direct path from input to output. This path contains only a small amount of relay contact resistance and wire resistance, resulting in minimal voltage loss. The AC output voltage is essentially equivalent to the input AC voltage, suitable for audio power supply requirements in 110V input scenarios where voltage conversion is not required. Since no additional magnetic or transformer components are introduced into the path, the system is highly efficient and has a simple electrical structure, which helps reduce size, lower cost, and improve long-term system stability. When the system determines that the current input is the second voltage mode (e.g., 220V input), the microcontroller outputs a high-level control signal, which drives the relay and transistor to conduct through the current-limiting resistor. This causes the relay coil to receive current and engage, thereby switching the internal contact state. The normally closed contacts that were originally closed open, and the normally open contacts that were originally open close. At this time, the AC input voltage is no longer directly connected to the output terminal, but is applied to the first winding of the step-down transformer, i.e., the primary coil, through the normally open contact path. This AC voltage forms a time-varying alternating positive and negative current in the first winding, exciting an alternating magnetic flux in the laminated silicon steel core. This alternating magnetic flux flows in a closed path inside the core and simultaneously passes through the second winding, i.e., the secondary coil. According to the law of electromagnetic induction, an induced electromotive force is generated in the second winding due to the change in magnetic flux. The effective value of this induced voltage depends on the turns ratio of the first and second windings. If the primary winding of the transformer has 880 turns and the secondary winding has 440 turns, the turns ratio is 2:1. This corresponds to a 220V AC input voltage being stepped down to approximately 110V output. Considering magnetic flux loss and leakage inductance, the actual output voltage is controlled between 108V and 112V. The output terminal of the second winding is connected to the AC output terminal through another set of closed contacts of the normally open contacts of the relay, realizing AC voltage step-down power supply. Even with high voltage input, it still provides the audio system with AC voltage consistent with the rated operating conditions.

[0037] When the normally open contact is closed, the AC input voltage generates an AC output voltage through the first and second windings of the step-down transformer. This includes: the AC input voltage being applied to the first winding of the step-down transformer through the normally open contact, the number of turns in the first winding being the first number of turns; the alternating magnetic flux generated in the core by the first winding being coupled to the second winding, the initial effective number of turns in the second winding being the second number of turns, and the ratio of the first number of turns to the second number of turns being the preset step-down ratio; the second winding performing electromagnetic induction step-down according to the preset step-down ratio, and the output voltage amplitude being the AC output voltage obtained by dividing the AC input voltage amplitude by the preset step-down ratio.

[0038] In one example, the AC output voltage is divided by resistors and rectified and filtered to obtain a second DC level. The tap position and effective number of turns of the second winding in the step-down transformer are then adjusted based on this second DC level, including: The AC output voltage is divided by the series connection of the third and fourth voltage divider resistors, and the output sampling voltage is obtained at the connection node of the third and fourth voltage divider resistors. The output sampling voltage is input into the second rectifier circuit for full-wave rectification to obtain the second pulsating DC voltage; The second pulsating DC voltage is filtered by the second filter circuit to obtain the second DC level; The tap position and effective number of turns of the second winding in the step-down transformer are adjusted according to the second DC level and the preset reference voltage.

[0039] In this example, a high-impedance resistor voltage divider structure is used for signal acquisition. Specifically, a series network consisting of a third and a fourth voltage divider resistor is connected in parallel at the AC output. One end of the third voltage divider resistor is connected to the phase line of the output AC voltage, and the other end of the fourth voltage divider resistor is connected to the AC ground or neutral line. The intermediate connection node is the output sampling voltage acquisition point. The voltage value at this node exhibits an AC waveform that changes synchronously with the output AC voltage, and due to the resistor voltage divider relationship, it is compressed to a lower, processable voltage amplitude range, controlled below 1V. The AC output sampling signal is input to the second rectifier circuit, which is a bridge full-wave rectifier structure. Four rectifier diodes form a bidirectional conduction path. During the positive half-cycle of the AC sampling voltage, the first and second diodes, positioned diagonally, conduct, forming the first conductive path and outputting a positive pulsating voltage. During the negative half-cycle, the other two diagonally positioned third and fourth diodes conduct, forming the second conductive path and outputting a positive voltage of the same polarity. This converts the input AC sampling signal into a unipolar second pulsating DC voltage with doubled frequency. This pulsating voltage still exhibits periodic fluctuations, making it unsuitable for direct comparison and regulation control. Therefore, a second filter circuit is used for smoothing. The second filter circuit employs an RC low-pass structure, consisting of a series current-limiting resistor and a parallel capacitor. Its function is to store energy at the peaks of the rectified output and release it between the troughs, forming a stable DC level, which is the second DC level. Its amplitude is linearly correlated with the effective value of the AC output voltage. The second DC level is sampled by the microcontroller's internal ADC channel and compared with a preset reference voltage. The reference voltage corresponds to the ideal DC sampling level that the target output voltage should present. For example, when outputting AC110V, the second DC level is 0.50V. Based on the difference ΔV between the sampled second DC level and the reference voltage, the microcontroller determines whether the current output voltage deviates from the target voltage range. If the deviation is within the set tolerance range, the current state is maintained; if the deviation exceeds the set threshold, the transformer tap adjustment mechanism is triggered. In buck mode, where the relay has introduced the input voltage to the transformer primary winding, the microcontroller uses I... 2 The C or SPI communication interface controls the tap switching chip or relay matrix to dynamically change the effective number of turns of the second winding of the transformer, thereby adjusting the output voltage. For example, when the second DC level is too high, it indicates that the output voltage is higher than the nominal value. At this time, the MCU adjusts the effective number of turns from 440 turns to 420 turns to achieve voltage reduction. Conversely, when the voltage is too low, the number of turns is adjusted to 460 turns to increase the output voltage.

[0040] In one example, the output sampled voltage is input into a second rectifier circuit for full-wave rectification to obtain a second pulsating DC voltage, including: Connect the output sampling voltage to the second AC input terminal of the second rectifier circuit; When the output sampling voltage is in the positive half-cycle, the fifth and sixth rectifier diodes arranged diagonally in the second rectifier circuit are turned on, generating a third positive voltage at the second DC output terminal of the second rectifier circuit; When the output sampling voltage is in the negative half-cycle, the seventh and eighth rectifier diodes arranged diagonally in the second rectifier circuit are turned on, generating a fourth positive voltage at the second DC output terminal of the second rectifier circuit. The third and fourth forward voltages are combined to form the second pulsating DC voltage.

[0041] In this example, a bridge full-wave rectifier structure is used as the core topology. This structure consists of a standard four-arm bridge configuration composed of the fifth, sixth, seventh, and eighth rectifier diodes. The fifth and sixth rectifier diodes are distributed on one diagonal of the bridge circuit, while the seventh and eighth rectifier diodes are distributed on the other diagonal. The output sampling voltage is connected to the two AC input terminals of the bridge rectifier circuit. The output sampling voltage here is a low-amplitude AC signal obtained by stepping down the AC output terminal through the preceding voltage divider network. Its frequency is consistent with the system power frequency, and the waveform exhibits typical alternating positive and negative half-cycle characteristics. When the output sampling voltage is in the positive half-cycle, i.e., the upper end of the sampling voltage is positive and the lower end is negative, the fifth rectifier diode conducts because the anode voltage is higher than the cathode voltage. The sixth rectifier diode is also in a forward conducting state because the cathode is grounded or at a low potential and the anode is connected to the lower end of the sampling. At this time, the current path flows from the upper end of the sampling through the fifth diode to the positive DC output, and then returns to the lower end of the sampling through the sixth diode, forming a complete closed current path, thereby generating a stable third positive voltage at the output of the second rectifier circuit. When the output sampling voltage enters the negative half-cycle, i.e., the lower end of the sampling is positive and the upper end is negative, the conduction path will be cut off. At this time, the seventh and eighth rectifier diodes form a new conduction path. The anode of the seventh diode is connected to the lower end of the sampling and the cathode is connected to the positive DC output. The anode of the eighth diode is connected to the negative DC output and the cathode is connected to the upper end of the sampling. The two form a closed loop. The current flows out from the lower end, through the seventh diode to the positive terminal, and then through the negative terminal through the eighth diode back to the upper end of the sampling, thereby forming a fourth positive voltage with the same direction at the rectifier output. Since the same polarity positive voltage is formed at the output terminal in both of the above two half cycles, the third positive voltage and the fourth positive voltage appear alternately in time and are consistent in direction. The result of their synthesis is a second pulsating DC voltage with a frequency twice that of the input sampling frequency and a periodic fluctuation in amplitude.

[0042] In one example, adjusting the tap position and effective number of turns of the second winding in the step-down transformer based on a second DC level and a preset reference voltage includes: The voltage deviation value is calculated based on the second DC level and the preset reference voltage; When the voltage deviation exceeds the preset deviation threshold, the microcontroller generates a tap adjustment command; The microcontroller sends the tap adjustment command to the tap switching control chip, which drives the tap relay on the second winding to switch to different tap positions, thereby changing the effective number of turns of the second winding.

[0043] In this example, the output AC voltage is converted into a stable second DC level through a high-impedance voltage divider network and a full-wave rectifier filter circuit. This second DC level is input to the microcontroller via an analog-to-digital converter and compared with a preset reference voltage. The reference voltage is the standard level value corresponding to the expected nominal voltage at the output terminal under voltage divider sampling conditions. The microcontroller performs a subtraction operation to calculate the voltage deviation between the current sampled value and the reference voltage, and obtains the magnitude of the deviation through absolute value calculation. This deviation is then compared with an internally set allowable deviation threshold. When the voltage deviation does not exceed the preset threshold, it indicates that the output voltage is still fluctuating within the allowable range. In this case, the microcontroller does not make any adjustments, maintaining the current tap position to avoid unnecessary frequent switching due to load transients or grid disturbances, thus reducing relay mechanical wear. However, when the deviation exceeds the preset threshold, it indicates that the output voltage shows a significant trend of being too high or too low, requiring active adjustment to restore the output voltage to near the target value. At this time, the microcontroller generates a tap adjustment command based on the deviation direction. If a high deviation is detected, a turn-down command is output; if a low deviation is detected, a turn-up command is output. This command is transmitted via I / O. 2 The command is sent to the tap switching control chip via the C or SPI bus interface. After receiving the command, the control chip drives the tap relay matrix on the second winding according to the corresponding logic, executing the relay closing action corresponding to the specific tap number. This switches the secondary winding from the original turns segment to a new turns segment, thereby dynamically changing the effective number of turns in the second winding. Since the transformer output voltage is proportional to the number of secondary turns, increasing the number of turns can increase the output voltage, and decreasing the number of turns can decrease the output voltage, restoring the output voltage to a preset stable range, thus achieving closed-loop control regulation.

[0044] The tap switching control chip drives the tap relay on the second winding to switch to different tap positions, changing the effective number of turns of the second winding. This includes: when the voltage deviation is positive and exceeds a preset deviation threshold, the tap switching control chip drives the tap relay to reduce the effective number of turns of the second winding from the second value to the first down-range value; when the voltage deviation is negative and the absolute value exceeds the preset deviation threshold, the tap switching control chip drives the tap relay to increase the effective number of turns of the second winding from the second value to the first up-range value; and changing the primary-secondary turns ratio of the transformer according to the first down-range or first up-range value, so that the AC output voltage returns to the preset voltage range.

[0045] After the relay contacts are closed, the AC input voltage is continuously sampled periodically and subjected to resistor voltage divider rectification and filtering to obtain the real-time first DC level. When the real-time first DC level deviates from the threshold range corresponding to the current voltage mode, the deviation timer is started to record the deviation duration. When the deviation duration is less than the preset duration threshold, the current relay contact state remains unchanged. When the deviation duration reaches or exceeds the preset duration threshold, the voltage mode judgment is re-executed and the relay contact state is switched.

[0046] A current sampling resistor is connected in series in the output circuit of the AC output voltage. The voltage drop across the current sampling resistor is sampled and converted to obtain the output load current value. The output load current value is compared with the preset rated current threshold and the preset overload current threshold. When the output load current value exceeds the rated current threshold but does not reach the overload current threshold, a current limiting resistor is connected in series in the output circuit to reduce the output current. When the output load current value reaches or exceeds the overload current threshold, the control relay contacts are opened to cut off the output circuit.

[0047] A freewheeling diode is connected in parallel between the collector and emitter of the driving transistor. The cathode of the freewheeling diode is connected to the positive terminal of the relay coil, and the anode is connected to the collector of the driving transistor. When the driving transistor switches from the on state to the off state, the current in the relay coil forms a discharge circuit through the freewheeling diode, clamping the reverse induced electromotive force generated by the coil to a preset safe voltage value. The total timing time from the microcontroller outputting the drive signal to the relay contacts completing the switching is controlled within a preset switching time range.

[0048] Reference Figure 5 This embodiment provides a voltage identification switching device for an adaptive audio system, including: Filter module 1 is used to perform resistive voltage division and rectification filtering on the AC input voltage to obtain the first DC level; Voltage mode determination module 2 is used to determine a first voltage mode when the first DC level is in a first threshold range, and to determine a second voltage mode when the first DC level is in a second threshold range. Contact closing module 3 is used to control the closing of normally closed or normally open contacts in the relay according to the first voltage mode or the second voltage mode; AC output module 4 is used to generate AC output voltage through a direct path when the normally closed contact is closed, and to generate AC output voltage through the first and second windings of the step-down transformer when the normally open contact is closed. The adjustment module 5 is used to perform resistive voltage division and rectification filtering on the AC output voltage to obtain a second DC level, and adjust the tap position and effective number of turns of the second winding in the step-down transformer according to the second DC level.

[0049] In this embodiment, the specific implementation of each unit in the above device embodiment is described in the above method embodiment, and will not be repeated here.

[0050] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0051] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A voltage identification switching method for an adaptive audio system, characterized in that, include: The AC input voltage is divided by resistors and rectified and filtered to obtain the first DC level. When the first DC level is within the first threshold range, it is determined to be the first voltage mode; when the first DC level is within the second threshold range, it is determined to be the second voltage mode. The normally closed or normally open contacts in the control relay are closed according to the first voltage mode or the second voltage mode. When the normally closed contact is closed, the AC input voltage generates an AC output voltage through a direct path; when the normally open contact is closed, the AC input voltage generates an AC output voltage through the first and second windings of the step-down transformer. The AC output voltage is divided by resistors and rectified and filtered to obtain a second DC level. The tap position and effective number of turns of the second winding in the step-down transformer are adjusted according to the second DC level.

2. The voltage identification and switching method for the adaptive audio system according to claim 1, characterized in that, The AC input voltage is divided by resistors and rectified and filtered to obtain the first DC level, including: The AC input voltage is divided by connecting the first voltage divider resistor and the second voltage divider resistor in series, and the AC sampling voltage is obtained at the connection node of the first voltage divider resistor and the second voltage divider resistor. The AC sampling voltage is input into the first rectifier circuit for full-wave rectification to obtain the first pulsating DC voltage. The first pulsating DC voltage is smoothed and filtered by the first filter circuit to obtain the first DC level.

3. The voltage identification and switching method for the adaptive audio system according to claim 2, characterized in that, The AC sampling voltage is input into the first rectifier circuit for full-wave rectification to obtain a first pulsating DC voltage, including: The AC sampling voltage is connected to the first AC input terminal of the first rectifier circuit via a current-limiting resistor; When the AC sampling voltage is in the positive half-cycle, the first rectifier diode and the second rectifier diode arranged diagonally in the first rectifier circuit are turned on, generating a first positive voltage at the first DC output terminal of the first rectifier circuit. When the AC sampling voltage is in the negative half-cycle, the third and fourth rectifier diodes arranged diagonally in the first rectifier circuit are turned on, generating a second positive voltage at the first DC output terminal of the first rectifier circuit. The first positive voltage and the second positive voltage are combined to form a first pulsating DC voltage.

4. The voltage identification and switching method for the adaptive audio system according to claim 1, characterized in that, When the first DC level is within a first threshold range, it is determined to be a first voltage mode; when the first DC level is within a second threshold range, it is determined to be a second voltage mode, including: The first DC level input analog-to-digital converter is sampled multiple times to obtain sampled data, and the average sampled value is calculated based on the sampled data. When the average sampled value is within the first threshold range, it is determined to be the first voltage mode; When the average sampled value is within the second threshold range, it is determined to be the second voltage mode.

5. The voltage identification and switching method for the adaptive audio system according to claim 1, characterized in that, Controlling the normally closed or normally open contacts in the relay to close according to the first voltage mode or the second voltage mode includes: When the first voltage mode is determined, the microcontroller outputs a low-level signal to turn off the driving transistor. When the driving transistor is turned off, the control relay coil is de-energized to keep the normally closed contact closed. When the second voltage mode is determined, the microcontroller outputs a high-level signal to drive the transistor to conduct through the base current-limiting resistor. When the transistor is driven to conduct, the coil loop current formed between the collector and emitter causes the normally open contact to close.

6. The voltage identification and switching method for the adaptive audio system according to claim 5, characterized in that, When the normally closed contact is closed, the AC input voltage generates an AC output voltage through a direct-through path. When the normally open contact is closed, the AC input voltage generates an AC output voltage through the first and second windings of the step-down transformer, including: When the normally closed contact is closed, the AC input voltage is directly connected to the output terminal through the normally closed contact to form a straight path, generating an AC output voltage that is the same as the AC input voltage; When the normally open contact is closed, the AC input voltage is applied to the first winding of the step-down transformer through the normally open contact. The first winding generates alternating magnetic flux in the iron core, and the second winding reduces the voltage according to the turns ratio through electromagnetic induction and outputs AC output voltage.

7. The voltage identification and switching method for the adaptive audio system according to claim 1, characterized in that, The AC output voltage is subjected to resistor voltage division and rectification filtering to obtain a second DC level. The tap position and effective number of turns of the second winding in the step-down transformer are then adjusted according to the second DC level, including: The AC output voltage is divided by the series connection of the third and fourth voltage divider resistors, and the output sampling voltage is obtained at the connection node of the third and fourth voltage divider resistors. The output sampling voltage is input into the second rectifier circuit for full-wave rectification to obtain the second pulsating DC voltage. The second pulsating DC voltage is filtered by the second filter circuit to obtain the second DC level; Adjust the tap position and effective number of turns of the second winding in the step-down transformer according to the second DC level and the preset reference voltage.

8. The voltage identification and switching method for the adaptive audio system according to claim 7, characterized in that, The output sampling voltage is input into the second rectifier circuit for full-wave rectification to obtain the second pulsating DC voltage, including: Connect the output sampling voltage to the second AC input terminal of the second rectifier circuit; When the output sampling voltage is in the positive half-cycle, the fifth and sixth rectifier diodes arranged diagonally in the second rectifier circuit are turned on, generating a third positive voltage at the second DC output terminal of the second rectifier circuit; When the output sampling voltage is in the negative half-cycle, the seventh and eighth rectifier diodes arranged diagonally in the second rectifier circuit are turned on, generating a fourth positive voltage at the second DC output terminal of the second rectifier circuit; The third positive voltage and the fourth positive voltage are combined to form a second pulsating DC voltage.

9. The voltage identification and switching method for an adaptive audio system according to claim 8, characterized in that, Adjusting the tap position and effective number of turns of the second winding in the step-down transformer according to the second DC level and the preset reference voltage includes: The voltage deviation value is calculated based on the second DC level and the preset reference voltage; When the voltage deviation exceeds a preset deviation threshold, the microcontroller generates a tap adjustment command; The microcontroller sends the tap adjustment command to the tap switching control chip, which drives the tap relay on the second winding to switch to different tap positions, thereby changing the effective number of turns of the second winding.

10. A voltage identification switching device for an adaptive audio system, characterized in that, The steps for implementing the voltage identification switching method of the adaptive audio system according to any one of claims 1 to 9 include: The filtering module is used to perform resistive voltage division and rectification filtering on the AC input voltage to obtain the first DC level; A voltage mode determination module is used to determine a first voltage mode when the first DC level is within a first threshold range, and to determine a second voltage mode when the first DC level is within a second threshold range. A contact closing module is used to control the normally closed or normally open contacts in a relay to close according to the first voltage mode or the second voltage mode. An AC output module is used to generate an AC output voltage from the AC input voltage through a direct path when the normally closed contact is closed, and to generate an AC output voltage from the AC input voltage through the first and second windings of a step-down transformer when the normally open contact is closed. The adjustment module is used to perform resistive voltage division and rectification filtering on the AC output voltage to obtain a second DC level, and adjust the tap position and effective number of turns of the second winding in the step-down transformer according to the second DC level.

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