Circuit for automatically switching input voltage and reducing input loss

Abstract

The invention discloses an input voltage automatic switching and input loss reducing circuit, which is characterized in that an automatic switching and loss reducing driving circuit samples an input alternating current voltage, a sampling signal is input to a control chip U1, the control chip U1 processes and compares the sampling signal, the current input voltage is judged, and when the input voltage is identified to be 90-132VAC, the input loss is reduced. The control chip U1 outputs a signal to trigger the conduction of the bidirectional silicon controlled rectifier Q1, double-voltage rectification output is carried out on the input voltage, and the control chip U1 is coupled with the energy-saving circuit through the photoelectric coupler U2. According to the circuit disclosed by the invention, a power supply can easily realize 90-264V global working voltage without generating EMC (Electro Magnetic Compatibility) interference under the condition that a small amount of cost is increased, and automatic switching of various different input voltages is realized through a hardware circuit and software program combined architecture; through a combined architecture of a hardware circuit and a software program, the power input loss is reduced, and the efficiency is improved by about 1.5%.

Description

Technical Field

[0001] The present invention relates to the field of circuit technologies, and particularly to a circuit for automatically switching input voltage and reducing input loss. Background Art

[0002] In today's application scenarios of electronic devices, it has become a key requirement for a power supply to be able to adapt to a wide range of input voltages. In particular, it is necessary to achieve an input operating voltage of 90 - 264VAC to meet the power grid supply standards in different regions of the world. Currently, when implementing this wide-voltage input function, the following three solutions are usually adopted, but these solutions all have certain limitations:

[0003] Adding a PFC circuit: Although the power factor correction (PFC) circuit can improve the power factor of the power supply, this solution has the problem of high cost. It requires additional circuit components and complex control algorithms, and at the same time increases the volume of the power supply, which is not conducive to the miniaturization design of the device. In addition, the PFC circuit will generate electromagnetic compatibility (EMC) interference during operation, which may affect the normal operation of other electronic devices, and additional filtering and shielding measures are required to solve the EMC problem, further increasing the cost and design complexity.

[0004] Increasing the component specifications: By selecting components with higher voltage resistance and greater power to adapt to the wide-voltage input range, this method will also increase the cost and the volume of the power supply. Moreover, due to the increase in the specifications of the components, their parasitic parameters will also increase accordingly, which is likely to generate EMC interference and affect the stability and reliability of the power supply.

[0005] Traditional power supply surge protection circuits: Such circuits have a certain role in preventing the surge current impact when the power supply starts, but they will increase the input power loss. During long-term use, the additional power loss will not only increase energy consumption, but also cause the power supply to heat up severely, reducing the efficiency and service life of the power supply.

[0006] Therefore, how to achieve stable operation of the power supply within the wide-voltage input range of 90 - 264VAC without significantly increasing the cost and volume, while reducing the input power loss and avoiding EMC interference, has become an urgent problem to be solved in the field of power supply design. Summary of the Invention

[0007] The purpose of the present invention is to overcome the defects of the prior art and provide a circuit for automatically switching input voltage and reducing input loss to solve the problems raised in the above background art.

[0008] An automatic input voltage switching and input loss reduction circuit, including a rectifier filter circuit, a power supply circuit, an automatic switching and loss reduction drive circuit, and an energy-saving circuit. The rectifier filter circuit is used to rectify and filter the input 110V / 220VAC alternating voltage to output a stable pure DC voltage. The automatic switching and loss reduction drive circuit includes a sampling module, a drive module, and a voltage switching module. The drive module includes a control chip U1 and an optocoupler U2. The sampling circuit samples the input alternating voltage, and the sampling signal is input to the control chip U1. The control chip U1 processes and compares the sampling signal to determine whether the current input voltage is 90 - 132VAC or 180 - 264VAC. When it is recognized that the input voltage is within 90 - 132VAC, the control chip U1 outputs a signal to trigger the bidirectional thyristor Q1 of the voltage switching circuit to conduct, and the voltage switching module performs a voltage doubler rectification on the input voltage and outputs it. The control chip U1 of the drive module is coupled to the energy-saving circuit through the optocoupler U2. The power supply circuit is used to supply power to the control chip U1 of the automatic switching and loss reduction drive circuit. The energy-saving circuit is used to dynamically adjust the working mode of the circuit according to the actual working state of the circuit.

[0009] Further, the rectifier filter circuit includes a rectifier bridge DB1, capacitors C1 and C2. The L line and the N line are connected to the AC input terminals of the rectifier bridge DB1. After rectification, a DC voltage is output. Capacitors C1 and C2 are connected in series at the output terminal of the rectifier bridge DB1, and the output terminal of the rectifier bridge DB1 is also electrically connected to the power output terminal HV+.

[0010] Further, the power supply circuit includes capacitors C3, resistors R4, R5, R3, diode D3, and capacitor C5. Resistors R4, R5, and R3 are connected in series in sequence. Capacitor C3 is connected in parallel with the series branch of resistors R4, R5, and R3. The anode of diode D1 is electrically connected to one end of resistor R3, and the cathode of diode D1 is electrically connected to diode D3 and capacitor C5 respectively. Diode D3 and capacitor C5 are electrically connected to the first pin of the control chip U1.

[0011] Further, the first pin of the control chip U1 is electrically connected to the power supply circuit, and the eighth pin of the control chip is electrically connected to one end of a capacitor C6, and the other end of the capacitor C6 is electrically connected to the power supply circuit.

[0012] Further, the sampling module includes a diode D2, a resistor R7, a resistor R8, a resistor R9, a resistor R11, a diode D4, a capacitor C7, and a resistor R12, and samples the input AC voltage. The diode D2, the resistor R7, the resistor R8, and the resistor R9 are connected in series in sequence. The resistor R9 is electrically connected to the resistor R11 and the anode of the diode D4 respectively. The cathode of the diode D4 is electrically connected to the 7th pin of the control chip U1, the capacitor C7, and the resistor R12 respectively. The resistor R9 is electrically connected to the 5th pin of the control chip U1. The 6th pin of the control chip U1 is electrically connected to a voltage switching circuit. The voltage switching circuit includes a triac Q1. The first anode of the triac Q1 is electrically connected to the L wire. The second anode of the triac Q1 is electrically connected between the capacitors C1 and C2 of the rectifier filter circuit. The gate of the triac Q1 is electrically connected to the capacitor C4 and then electrically connected to the 6th pin of the control chip U1. One end of a fuse resistor FR2 is electrically connected to the first anode of the triac Q1. The other end of the fuse resistor FR2 is electrically connected to a resistor R10. The resistor R10 is electrically connected to the gate of the triac Q1 and the capacitor C4 respectively.

[0013] Further, the 1st pin of the control chip U1 is electrically connected to the resistor R13 and then electrically connected to an input terminal of an optocoupler U2. The other input terminal of the optocoupler U2 is electrically connected to the 2nd pin of the control chip U1.

[0014] Further, the energy-saving circuit includes a main energy-saving module composed of a resistor R16, a resistor R17, a resistor R18, a triode Q3, a diode D6, a resistor R19, a capacitor C9, a resistor R20, a MOS transistor Q2, a fuse resistor FR1, and a zener diode D7. The resistor R16, the resistor R17, and the resistor R18 are connected in series at the output terminal of the rectifier bridge DB1. The base of the triode Q3 is connected to the resistor R17, the resistor R18, and the anode of the diode D6 respectively. The emitter of the triode Q3 is electrically connected to the resistor R19. The collector of the triode Q3 is electrically connected to the capacitor C9, the anode of the zener diode D7, and the source of the MOS transistor Q2 respectively. A fuse resistor FR1 is electrically connected between the source and the drain of the MOS transistor Q2. The gate of the MOS transistor Q2 is electrically connected to the cathode of the zener diode D7 and the resistor R20 respectively.

[0015] Further, the emitter of the optocoupler U2 is electrically connected to the resistors R14 and R15 and then grounded. After the emitter of the optocoupler U2 is electrically connected to the resistor R14, it is also electrically connected to the gate of the MOS transistor Q2, the resistor R20, and the cathode of the diode D7 respectively. The resistors R1, R2, and R3 are connected in series at the output terminal of the rectifier bridge DB1. The resistor R3 is electrically connected to the collector of the optocoupler U2. The collector of the optocoupler U2 is also electrically connected to the cathode of the zener diode D5 and the capacitor C8 respectively. The anode of the diode D5 and the capacitor C8 are electrically connected to the resistor R18.

[0016] Advantages of the present invention:

[0017] The automatic input voltage switching and input loss reduction circuit proposed by the present invention has the following remarkable advantages:

[0018] Achieving wide input voltage with low cost: Through ingenious circuit design and reasonable component selection, only a very small increase in cost is required to enable the power supply to easily achieve a global operating voltage range of 90 - 264V. This feature enables the power supply to operate stably in different regional power grid environments, greatly improving the universality and market adaptability of the product. There is no need to design different power supply schemes for different regional power grid standards, reducing R & D and production costs.

[0019] Avoiding EMC interference: Different from traditional solutions such as adding PFC circuits or increasing the specifications of components, this circuit does not generate EMC interference during the process of achieving wide input voltage. This not only ensures the stability and reliability of the power supply itself but also avoids electromagnetic interference to other surrounding electronic devices, reducing additional filtering and shielding measures, further reducing costs and design complexity.

[0020] Efficient automatic switching function: Adopting an architecture that combines a hardware circuit and a software program, it realizes automatic switching for multiple different input voltages. The sampling module can accurately sample the input AC voltage in real time. The control chip determines whether the current input voltage is in the range of 90 - 132VAC or 180 - 264VAC and quickly outputs the corresponding control signal to trigger the voltage switching module to adjust the voltage. The entire switching process is fast and accurate, without manual intervention, ensuring stable output of the power supply under different input voltages and improving the adaptability and reliability of the power supply.

[0021] Significantly reducing input loss: Through the collaborative work of an energy-saving circuit and an automatic switching and loss reduction drive circuit, the working mode is dynamically adjusted according to the actual working state of the circuit, effectively reducing the input power loss of the power supply. In the initial stage when the control chip is powered on, the circuit operates in a conventional mode to ensure normal startup of the device. After 3S of power-on, the energy-saving circuit starts to function. By controlling the on and off states of the triode and MOS tube, the current bypasses the fuse resistor and selects a path with a smaller internal resistance, thus greatly reducing the output power loss. Through actual testing, this circuit can improve the power supply efficiency by about 1.5%. During long-term use, it can significantly save energy consumption, reduce usage costs, and at the same time reduce the heat generation of the power supply and extend the service life of the power supply. Description of the Drawings

[0022] Figure 1 It is the circuit schematic diagram of the present invention. Detailed Embodiment

[0023] The present invention provides an input voltage automatic switching and input loss reduction circuit, as Figure 1 described, which includes a rectifier filter circuit, a power supply circuit, an automatic switching and loss reduction drive circuit, and an energy-saving circuit. The rectifier filter circuit is used to rectify and filter the input 110V / 220VAC alternating voltage to output a stable pure DC voltage. The automatic switching and loss reduction drive circuit includes a sampling module, a drive module, and a voltage switching module. The drive module includes a control chip U1 and an optocoupler U2. The sampling circuit samples the input alternating voltage, and the sampling signal is input to the control chip U1. The control chip U1 processes and compares the sampling signal to determine whether the current input voltage is 90 - 132VAC or 180 - 264VAC. When it is recognized that the input voltage is within 90 - 132VAC, the control chip U1 outputs a signal to trigger the bidirectional thyristor Q1 of the voltage switching circuit to conduct, and the voltage switching module performs a voltage doubler rectification on the input voltage and outputs it. The control chip U1 of the drive module is coupled to the energy-saving circuit through the optocoupler U2. The power supply circuit is used to supply power to the control chip U1 of the automatic switching and loss reduction drive circuit. The energy-saving circuit is used to dynamically adjust the working mode of the circuit according to the actual working state of the circuit.

[0024] The rectifier filter circuit includes a rectifier bridge DB1, capacitors C1, and C2. The L line and the N line are connected to the AC input terminals of the rectifier bridge DB1. After rectification, a DC voltage is output. Capacitors C1 and C2 are connected in series at the output terminal of the rectifier bridge DB1. The output terminal of the rectifier bridge DB1 is also electrically connected to the power output terminal HV+.

[0025] After the rectification of the rectifier bridge DB1, the 110V / 220VAC alternating voltage is converted into a DC voltage. Capacitors C1 and C2 are connected in series at the output terminal of the rectifier bridge DB1 to play a filtering role, further smoothing the DC voltage, reducing voltage fluctuations, and outputting a stable pure DC voltage for the next stage to use. The output terminal of the rectifier bridge DB1 is also electrically connected to the power output terminal HV+ to provide electrical energy for the subsequent circuits that require power output.

[0026] The power supply circuit includes capacitors C3, resistors R4, R5, R3, diode D3, and capacitor C5. Resistors R4, R5, and R3 are connected in series in sequence. Capacitor C3 is connected in parallel with the series branch of resistors R4, R5, and R3. The anode of diode D1 is electrically connected to one end of resistor R3. The cathode of diode D1 is electrically connected to diode D3 and capacitor C5 respectively. Diode D3 and capacitor C5 are electrically connected to the first pin of the control chip U1.

[0027] The input of the power supply circuit is a DC voltage that has been preliminarily processed by a rectification and filtering circuit (obtained by rectifying the 110V / 220VAC input voltage through the rectifier bridge DB1 and filtering it with electrolytic capacitors C1 and C2). Resistors R4, R5, and R3 are connected in series in sequence, and capacitor C3 is connected in parallel with the series branch of these three resistors. Using its capacitive reactance characteristic to AC signals, capacitor C3 presents capacitive reactance to the AC component when there is an AC component in the circuit, hindering its passage, and thus generating a voltage drop across capacitor C3, achieving the function of stepping down the input voltage. The anode of diode D1 is connected to one end of resistor R3. After the voltage stepped down by capacitor C3 still has an AC component, diode D1 uses its unidirectional conductivity to conduct during the positive half cycle of the AC voltage, allowing the current to flow through to the subsequent circuit; it cuts off during the negative half cycle of the AC voltage, preventing the current from flowing in the reverse direction, thereby converting the AC component into a unidirectional DC component and making the output voltage closer to the ideal DC voltage. The cathode of diode D1 is respectively connected to diode D3 and capacitor C5. Diode D3 is a zener diode that operates in the reverse breakdown region. When the reverse voltage reaches its zener voltage, even if the current changes within a large range, the voltage across its two ends can be basically stable. In this circuit, diode D3 stabilizes the output voltage at a specific value (selected according to the power supply requirements of control chip U1, such as 5V or 3.3V, etc.), meeting the voltage requirements for the normal operation of control chip U1. Capacitor C5 plays a filtering role. Although the voltage after rectification is already a unidirectional DC, there are still ripples (voltage fluctuations). Capacitor C5 can store and release charges. It charges when the voltage rises, absorbing the excess charges; it discharges when the voltage drops, releasing charges, thereby smoothing the voltage fluctuations and further reducing the ripples, making the output DC voltage more stable and smoother. The stable DC voltage after stepping down, rectifying, stabilizing, and filtering is connected to the first pin of control chip U1 to supply power to control chip U1, enabling control chip U1 to normally run the internal software algorithm, process and compare the input sampled signals, and achieve functions such as automatic switching and loss reduction control of the entire circuit. The first pin of control chip U1 is connected to diode D3 and capacitor C5 in the power supply circuit, directly obtaining the stable DC voltage after voltage stabilization and filtering. This is the main power input for the normal operation of control chip U1, providing electrical energy for various circuit modules inside the chip, enabling it to execute the predetermined programs and functions, such as analyzing and processing the input sampled signals and outputting control signals to adjust the working state of the circuit.

[0028] The first pin of control chip U1 is electrically connected to the power supply circuit. The eighth pin of the control chip is electrically connected to one end of a capacitor C6, and the other end of capacitor C6 is electrically connected to the power supply circuit.

[0029] The eighth pin of the control chip U1 is connected to one end of the capacitor C6, and the other end of the capacitor C6 is connected to the power supply circuit. The capacitor C6 plays a role in filtering and stabilizing the voltage here. On the one hand, it can filter out the high-frequency interference signals that may exist in the power supply circuit, preventing these interference signals from entering the interior of the control chip U1 and affecting the normal operation of the chip. On the other hand, when the power supply voltage has an instantaneous fluctuation, the capacitor C6 can buffer this fluctuation by storing and releasing charges, so that the voltage at the eighth pin of the control chip U1 remains relatively stable, which helps the stable operation of the internal circuit of the control chip U1 and ensures the accuracy of its signal processing and output control instructions. Through the above connection method, the power supply circuit provides a stable and reliable power supply for the control chip U1. At the same time, in cooperation with components such as the capacitor C6, it enhances the stability and anti-interference ability of the control chip U1 to work, ensuring that the entire circuit system can operate normally and stably.

[0030] The sampling module includes a diode D2, a resistor R7, a resistor R8, a resistor R9, a resistor R11, a diode D4, a capacitor C7, and a resistor R12, which samples the input AC voltage. The diode D2, the resistor R7, the resistor R8, and the resistor R9 are connected in series in sequence. The resistor R9 is electrically connected to the resistor R11 and the anode of the diode D4 respectively. The cathode of the diode D4 is electrically connected to the seventh pin of the control chip U1, the capacitor C7, and the resistor R12 respectively. The resistor R9 is electrically connected to the fifth pin of the control chip U1. The sixth pin of the control chip U1 is electrically connected to a voltage switching circuit. The voltage switching circuit includes a triac Q1. The first anode of the triac Q1 is electrically connected to the L wire. The second anode of the triac Q1 is electrically connected between the capacitors C1 and C2 of the rectifier filter circuit. The gate of the triac Q1 is electrically connected to the capacitor C4 and then electrically connected to the sixth pin of the control chip U1. One end of a fuse resistor FR2 is electrically connected to the first anode of the triac Q1, and the other end of the fuse resistor FR2 is electrically connected to a resistor R10. The resistor R10 is electrically connected to the gate of the triac Q1 and the capacitor C4 respectively.

[0031] The input 110V / 220VAC AC voltage first enters the sampling module. Diode D2, resistor R7, resistor R8, and resistor R9 are connected in series in sequence. This part of the circuit plays the role of voltage division and preliminary rectification. When the AC voltage passes through diode D2, using the unidirectional conductivity of the diode, it conducts during the positive half-cycle of the AC voltage and cuts off during the negative half-cycle, making the current passing through this series branch a unidirectional pulsating current. At the same time, resistors R7, R8, and R9 play the role of voltage division, reducing the input AC voltage by a certain ratio to adapt to the processing requirements of the subsequent circuit. Resistor R9 is electrically connected to resistor R11 and the anode of diode D4 respectively. Resistor R11 may play the role of further current limiting or voltage division, while diode D4 rectifies the signal again or performs a level conversion. The cathode of diode D4 is electrically connected to the 7th pin of control chip U1, capacitor C7, and resistor R12 respectively. Capacitor C7 plays a filtering role, filtering out high-frequency interference signals to make the sampling signal input to the 7th pin of control chip U1 more pure and smooth. Resistor R12 plays the role of current limiting or biasing to ensure that the signal input to control chip U1 meets its electrical characteristic requirements. In addition, resistor R9 is also electrically connected to the 5th pin of control chip U1 to provide another reference signal for control chip U1 or for other specific function judgments. Through these connections, the sampling module transmits the processed input AC voltage signal to control chip U1, providing a basis for subsequent voltage judgment and switching control.

[0032] After receiving the signal from the sampling module, control chip U1 processes and compares the sampling signal using internal software algorithms. Its main purpose is to determine whether the current input voltage is in the range of 90 - 132VAC or 180 - 264VAC. Specifically, control chip U1 analyzes the characteristics such as the amplitude and frequency of the input signal and compares them with the internally preset thresholds to determine the range of the input voltage. When control chip U1 identifies that the input voltage is between 90 - 132VAC, its 6th pin outputs a high-level signal. This high-level signal is used to trigger the conduction of triac Q1 in the voltage switching circuit. When the input voltage is between 180 - 264VAC, control chip U1 does not output a trigger signal, and triac Q1 remains in the cut-off state, and the circuit operates in a conventional rectification and filtering mode.

[0033] The first anode of the triac Q1 is electrically connected to the L line, the second anode is electrically connected between the capacitors C1 and C2 of the rectifier filter circuit, and the gate is electrically connected to the 6th pin of the control chip U1 after being connected to the capacitor C4. When the 6th pin of the control chip U1 outputs a high-level signal, this signal triggers the triac Q1 to conduct through the capacitor C4. After the triac Q1 conducts, the input voltage will perform a voltage doubler rectification output. The specific process is that within one half-cycle of the AC voltage, the current passes through the triac Q1 and related circuit components to charge the capacitor, and within the other half-cycle, the capacitor discharges and is superimposed on the power supply voltage, thereby realizing voltage doubler rectification and increasing the output voltage to meet the requirements of specific loads or circuit operations.

[0034] One end of the fuse resistor FR2 is electrically connected to the first anode of the triac Q1, and the other end is electrically connected to a resistor R10. The resistor R10 is respectively electrically connected to the gate of the triac Q1 and the capacitor C4. The fuse resistor FR2 plays an overcurrent protection role. When an abnormally large current appears in the circuit, the fuse resistor FR2 will blow and cut off the circuit to protect the triac Q1 and other circuit components from being damaged. In addition to participating in the triggering process of the triac Q1, the resistor R10 and the capacitor C4 may also play roles in filtering, delaying, or stabilizing the triggering signal to ensure that the triac Q1 can be reliably triggered and operate stably.

[0035] The 1st pin of the control chip U1 is electrically connected to the resistor R13 and then to one input terminal of the optocoupler U2, and the other input terminal of the optocoupler U2 is electrically connected to the 2nd pin of the control chip U1.

[0036] The 1st pin of the control chip U1 is electrically connected to the resistor R13 and then to one input terminal of the optocoupler U2, and the 2nd pin is connected to the other input terminal of the optocoupler U2. Through this connection method, the control chip U1 can control the working state of the energy-saving circuit through the optocoupler U2 to realize the management of the power consumption of the entire circuit.

[0037] Within 3 seconds after the control chip U1 is powered on, the second pin of the control chip U1 is at a high level, and at this time, the optocoupler U2 is not conducting. Since the emitter of the optocoupler U2 is electrically connected to the resistors R14 and R15 and then grounded, and its emitter is also connected to the gate of the MOS transistor Q2 in the energy-saving circuit and other components, when the optocoupler U2 is not conducting, the gate of the MOS transistor Q2 cannot obtain sufficient voltage, resulting in the MOS transistor Q2 being cut off. At the same time, the triode Q3 is also cut off, and the current flows through the fuse resistor FR1. Since the resistance value of FR1 is fixed, a relatively large output power loss will occur at this time. After 3 seconds, the second pin of U1 becomes low level, and the optocoupler U2 conducts. After the optocoupler U2 conducts, through its internal optoelectronic conversion mechanism, the electrical signal is transmitted to the output end, causing the potential of the relevant circuit connected to its emitter to change. Specifically, after the optocoupler U2 conducts, the triode Q3 conducts. After the triode Q3 conducts, its internal resistance is very small. At this time, the current no longer mainly flows through the fuse resistor FR1, but through the triode Q3 with a smaller internal resistance, greatly reducing the output power loss and achieving the purpose of energy saving. At the same time, the conduction of the optocoupler U2 will also affect the gate voltage of the MOS transistor Q2 through the connection relationship, thereby controlling the conduction and cut-off states of the MOS transistor Q2 and further optimizing the energy-saving effect. For example, when U1 is not in use, through the voltage division effect of the resistors R16, R17, and R18, and the collaborative effect of components such as the diode D6, resistor R19, capacitor C9, and resistor R20, the working states of the triode Q3 and the MOS transistor Q2 are controlled to achieve deep energy saving of the analog circuit part. In summary, the automatic switching and loss-reducing drive circuit obtains the input voltage information through the sampling module, the control chip U1 analyzes and judges and outputs a control signal, the voltage switching module realizes the automatic switching of the voltage, and at the same time combines with the energy-saving circuit to achieve the purpose of reducing power consumption, so as to ensure that the entire circuit system can operate efficiently and stably under different input voltage conditions.

[0038] The energy-saving circuit includes a main energy-saving module composed of the resistors R16, R17, R18, triode Q3, diode D6, resistor R19, capacitor C9, resistor R20, MOS transistor Q2, fuse resistor FR1, and zener diode D7. The resistors R16, R17, and R18 are connected in series at the output end of the rectifier bridge DB1. The base of the triode Q3 is respectively connected to the anodes of the resistors R17, R18, and diode D6. The emitter of the triode Q3 is electrically connected to the resistor R19. The collector of the triode Q3 is respectively electrically connected to the anode of the capacitor C9, the anode of the zener diode D7, and the source of the MOS transistor Q2. A fuse resistor FR1 is electrically connected between the source and the drain of the MOS transistor Q2. The gate of the MOS transistor Q2 is respectively electrically connected to the cathode of the zener diode D7 and the resistor R20.

[0039] The emitter of the optocoupler U2 is grounded after being electrically connected to resistors R14 and R15. After the emitter of the optocoupler U2 is electrically connected to resistor R14, it is also respectively electrically connected to the gate of MOS transistor Q2, resistor R20, and the cathode of diode D7. Resistors R1, R2, and R3 are connected in series at the output terminal of the rectifier bridge DB1. Resistor R3 is electrically connected to the collector of the optocoupler U2. The collector of the optocoupler U2 is also respectively electrically connected to the cathode of the zener diode D5 and capacitor C8. The anode of diode D5, capacitor C8, and resistor R18 are electrically connected.

[0040] The energy-saving circuit includes a main energy-saving module composed of resistor R16, resistor R17, resistor R18, triode Q3, diode D6, resistor R19, capacitor C9, resistor R20, MOS transistor Q2, fuse resistor FR1, and zener diode D7. It is called the "main energy-saving module" because it plays a core role in the entire energy-saving process. By controlling and adjusting the key components in the circuit, the purpose of reducing power consumption is achieved. Resistors R16, R17, and R18 are connected in series at the output terminal of the rectifier bridge DB1, and they form a voltage-dividing network. After the DC voltage output by the rectifier bridge DB1 is divided by these three resistors, a specific voltage is generated between resistors R17 and R18, and this voltage is used to control the base potential of triode Q3. The base of triode Q3 is respectively connected to resistors R17, R18, and the anode of diode D6. Diode D6 plays a role in protecting the base of triode Q3 to prevent the base from being damaged by reverse overvoltage. The emitter of triode Q3 is electrically connected to resistor R19. Resistor R19 plays a current-limiting role, protecting the emitter junction of triode Q3 and affecting the working current of triode Q3. The collector of triode Q3 is respectively electrically connected to capacitor C9, the anode of zener diode D7, and the source of MOS transistor Q2. Capacitor C9 plays a role in filtering and stabilizing the signal, reducing the influence of voltage fluctuations on the collector potential of triode Q3; zener diode D7 is used to stabilize the reference voltage of the gate of MOS transistor Q2. A fuse resistor FR1 is electrically connected between the source and drain of MOS transistor Q2. The fuse resistor FR1 plays an overcurrent protection role. When the current passing through MOS transistor Q2 is too large, the fuse resistor FR1 will blow, protecting MOS transistor Q2 from being damaged. The gate of MOS transistor Q2 is respectively electrically connected to the cathode of zener diode D7 and resistor R20. Resistor R20 plays a voltage-dividing or current-limiting role, further adjusting the gate voltage of MOS transistor Q2, thereby controlling the on and off states of MOS transistor Q2.

[0041] During the initial power-on stage (within 3 seconds) of the control chip U1, the second pin of the control chip U1 is at a high level, and at this time, the optocoupler U2 is not conducting. Since the emitter of the optocoupler U2 is electrically connected to resistors R14 and R15 and then grounded, and its emitter is also connected to components such as the gate of MOS transistor Q2, resistor R20, and the cathode of diode D7, when the optocoupler U2 is not conducting, the gate of MOS transistor Q2 cannot obtain sufficient voltage, resulting in the cutoff of MOS transistor Q2. At the same time, transistor Q3 is also cutoff, and the current flows through the fuse resistor FR1. Since the resistance value of FR1 is fixed, a relatively large output power loss will occur at this time. After 3 seconds of power-on of the control chip U1, the second pin of the control chip U1 becomes low level, and the optocoupler U2 conducts. After the optocoupler U2 conducts, the light-emitting diode inside it emits light, causing the photosensitive element to conduct, thereby transmitting the electrical signal from the input end to the output end. At this time, the potential of the relevant circuit connected to the emitter of the optocoupler U2 changes. Specifically, after the optocoupler U2 conducts, the base potential of transistor Q3 changes, and then transistor Q3 conducts.

[0042] After transistor Q3 conducts, its internal resistance is very small. At this time, the current no longer mainly flows through the fuse resistor FR1, but through transistor Q3 with a smaller internal resistance, greatly reducing the output power loss and achieving the purpose of energy saving.

[0043] The energy-saving mechanism when the control chip U1 is not working. When the control chip U1 is not in use, through the voltage division of resistors R16, R17, and R18, a specific voltage will be generated at the base of transistor Q3. If this voltage meets the conduction condition of transistor Q3, transistor Q3 will conduct. After transistor Q3 conducts, through the collector connection relationship, it will affect the gate voltage of MOS transistor Q2. For example, when transistor Q3 conducts, the gate voltage of MOS transistor Q2 will increase. When the gate voltage reaches the conduction threshold of MOS transistor Q2, MOS transistor Q2 conducts. After MOS transistor Q2 conducts, its on-resistance is small. Compared with the resistance value of the fuse resistor FR1, it can greatly reduce the power loss of the circuit. At the same time, components such as zener diode D7 and resistor R20 work together to ensure that the gate voltage of MOS transistor Q2 is stable within a suitable range, maintaining the conduction state of MOS transistor Q2 and achieving the energy-saving effect.

[0044] In addition, the optocoupler U2 cooperates with other components. Resistors R1, R2, and R3 are connected in series at the output of the rectifier bridge DB1, and resistor R3 is electrically connected to the collector of the optocoupler U2. The collector of the optocoupler U2 is also electrically connected to the cathode of the zener diode D5 and the capacitor C8, and the anode of the diode D5, the capacitor C8 are electrically connected to the resistor R18. The zener diode D5 plays a voltage stabilizing role to ensure that the voltage at the collector of the optocoupler U2 is stable within a certain range, and the capacitor C8 plays a filtering role to reduce voltage fluctuations. They work together with the optocoupler U2 to ensure that the energy-saving circuit can operate stably in different working states and accurately adjust the power consumption of the circuit according to the control signal.

[0045] In summary, through the cooperative work of the triode Q3, the MOS transistor Q2, and related resistors, capacitors, diodes and other components, combined with the signal transmission and control function of the optocoupler U2, the energy-saving circuit dynamically adjusts the working mode of the circuit according to the actual working state of the circuit (such as the working state of U1, the input voltage, etc.) to achieve the purpose of reducing power consumption.

[0046] Resistors R16, R17, and R18 are connected in series at the output of the rectifier bridge DB1, which plays a voltage-dividing role and provides a suitable bias voltage for the base of the triode Q3. The base of the triode Q3 is respectively connected to the resistors R17, R18, and the anode of the diode D6. The diode D6 plays a role in protecting the base of the triode Q3 to prevent abnormal base voltage. The emitter of the triode Q3 is electrically connected to the resistor R19, and the resistor R19 plays a current-limiting role to protect the triode Q3 and also participates in regulating the working state of the triode Q3. The collector of the triode Q3 is respectively electrically connected to the capacitor C9, the anode of the zener diode D7, and the source of the MOS transistor Q2. The capacitor C9 plays a role in filtering or stabilizing the signal, and the zener diode D7 plays a voltage-stabilizing role to provide a stable reference voltage for the gate of the MOS transistor Q2. A fuse resistor FR1 is electrically connected between the source and drain of the MOS transistor Q2, and the fuse resistor FR1 plays a role in protecting the MOS transistor Q2 to prevent damage due to overcurrent. The gate of the MOS transistor Q2 is respectively electrically connected to the cathode of the zener diode D7 and the resistor R20. The resistor R20 plays a voltage-dividing or current-limiting role to further regulate the gate voltage of the MOS transistor Q2, thereby controlling the on and off states of the MOS transistor Q2. Working principle: Within 3S after U1 is powered on, the second pin of U1 is at a high level. At this time, the optocoupler U2 is not conducting, the triode Q3 is cut off, and the current flows through FR1. Since the resistance value of FR1 is fixed, a relatively large output power loss will occur. After 3S, the second pin of U1 becomes low level, the optocoupler U2 conducts, and through the signal transmission of the optocoupler U2, the triode Q3 is turned on. Since the internal resistance of the triode Q3 is very small, the output power loss is greatly reduced, achieving the purpose of energy saving. When U1 is not in use, through the voltage-dividing effect of the resistors R16, R17, and R18, and the coordinated action of components such as the diode D6, the resistor R19, the capacitor C9, and the resistor R20, the working states of the triode Q3 and the MOS transistor Q2 are controlled, further reducing the circuit power consumption and realizing energy saving in the analog circuit part.

[0047] The control chip U1 processes and compares the sampling signals, judges the current input voltage range, and outputs signals to trigger functions such as the conduction of the triac Q1. The control chip U1 can be a microcontroller (MCU) with the ability to collect and process analog signals and digital output control functions, such as: the STM32 series of STMicroelectronics, the PIC series of Microchip, etc. The control chip U1 can also be a chip dedicated to power management and control. Such chips usually integrate functions such as voltage sampling, signal processing, and output control. For example, some power management chips of TI (Texas Instruments).

[0048] The input voltage automatic switching and input loss reduction circuit proposed by the present invention has the following remarkable advantages:

[0049] Low-cost implementation of wide-voltage input: Through ingenious circuit design and reasonable component selection, only a minimal increase in cost is required to enable the power supply to easily achieve a global operating voltage range of 90 - 264V. This feature allows the power supply to operate stably in different regional grid environments, greatly enhancing the universality and market adaptability of the product. There is no need to design different power supply solutions for different regional grid standards, reducing R & D and production costs.

[0050] Avoid EMC interference: Different from traditional solutions that add PFC circuits or increase component specifications, this circuit does not generate EMC interference during the process of achieving wide-voltage input. This not only ensures the stability and reliability of the power supply itself but also avoids electromagnetic interference to other surrounding electronic devices, reducing additional filtering and shielding measures, further lowering costs and design complexity.

[0051] Efficient automatic switching function: Adopting an architecture that combines hardware circuits and software programs, it realizes automatic switching for multiple different input voltages. The sampling module can accurately sample the input AC voltage in real time. The control chip determines whether the current input voltage is in the range of 90 - 132VAC or 180 - 264VAC and quickly outputs the corresponding control signal to trigger the voltage switching module to adjust the voltage. The entire switching process is fast and accurate, without manual intervention, ensuring stable output of the power supply under different input voltages and enhancing the adaptability and reliability of the power supply.

[0052] Significantly reduce input losses: Through the coordinated operation of the energy-saving circuit, automatic switching, and loss-reducing drive circuit, the working mode is dynamically adjusted according to the actual working state of the circuit, effectively reducing the input power loss of the power supply. At the initial stage when the control chip is powered on, the circuit operates in the conventional mode to ensure normal startup of the device; after 3S of power-on, the energy-saving circuit starts to function. By controlling the on and off states of the triode and MOS transistor, the current bypasses the fuse resistor and selects a path with a smaller internal resistance, thus greatly reducing the output power loss. Through actual testing, this circuit can improve the power supply efficiency by approximately 1.5%. During long-term use, it can significantly save energy consumption, reduce usage costs, while reducing power supply heat generation and extending the service life of the power supply.

Claims

1. A circuit for automatically switching input voltage and reducing input loss, characterized in that: It includes a rectifier and filter circuit, a power supply circuit, an automatic switching and loss reduction drive circuit, and an energy-saving circuit. The rectifier and filter circuit is used to rectify and filter the input 110V / 220VAC AC voltage and output a stable pure DC voltage. The automatic switching and loss reduction drive circuit includes a sampling module, a drive module, and a voltage switching module. The drive module includes a control chip U1 and a photoelectric coupler U2. The sampling circuit samples the input AC voltage, and the sampling signal is input to the control chip U1. The control chip U1 processes and compares the sampling signal to determine whether the current input voltage is 90-132VAC or 180-264VAC. When it is identified that the input voltage is 90-132VAC, the control chip U1 outputs a signal to trigger the bidirectional thyristor Q1 of the voltage switching circuit to turn on, and the voltage switching module performs double voltage rectification and output on the input voltage. The control chip U1 of the drive module is coupled to the energy-saving circuit through the photoelectric coupler U2. The power supply circuit is used to power the control chip U1 of the automatic switching and loss reduction drive circuit. The energy-saving circuit is used to dynamically adjust the working mode of the circuit according to the actual working state of the circuit.

2. The circuit for automatically switching input voltage and reducing input loss according to claim 1, characterized in that: The rectifier and filter circuit includes a rectifier bridge DB1 and capacitors C1 and C2. The L line and the N line are connected to the AC input end of the rectifier bridge DB1. After rectification, a DC voltage is output. The capacitors C1 and C2 are connected in series to the output end of the rectifier bridge DB1. The output end of the rectifier bridge DB1 is also electrically connected to the power output end HV+.

3. The circuit for automatically switching input voltage and reducing input loss according to claim 1, characterized in that: The power supply circuit includes a capacitor C3, a resistor R4, a resistor R5, a resistor R3, a diode D3 and a capacitor C5. The resistors R4, R5 and R3 are connected in series in sequence. The capacitor C3 is connected in parallel with the series branch of the resistors R4, R5 and R3. The anode of the diode D1 is electrically connected to one end of the resistor R3. The cathode of the diode D1 is electrically connected to the diode D3 and the capacitor C5 respectively. The diode D3 and the capacitor C5 are electrically connected to the first pin of the control chip U1.

4. The circuit for automatically switching input voltage and reducing input loss according to claim 3, characterized in that: The first pin of the control chip U1 is electrically connected to the power supply circuit, the eighth pin of the control chip is electrically connected to one end of a capacitor C6, and the other end of the capacitor C6 is electrically connected to the power supply circuit.

5. The circuit for automatically switching input voltage and reducing input loss according to claim 1, characterized in that: The sampling module includes a diode D2, a resistor R7, a resistor R8, a resistor R9, a resistor R11, a diode D4, a capacitor C7, and a resistor R12, and samples the input AC voltage. The diode D2, the resistor R7, the resistor R8, and the resistor R9 are connected in series in sequence. The resistor R9 is electrically connected to the anode of the resistor R11 and the diode D4 respectively. The cathode of the diode D4 is electrically connected to the 7th pin of the control chip U1, the capacitor C7, and the resistor R12 respectively. The resistor R9 is electrically connected to the 5th pin of the control chip U1, and the 6th pin of the control chip U1 is electrically connected to the A voltage switching circuit, the voltage switching circuit includes a bidirectional thyristor Q1, a first anode of the bidirectional thyristor Q1 is electrically connected to the L line, a second anode of the bidirectional thyristor Q1 is electrically connected between capacitors C1 and C2 of the rectifier and filter circuit, a gate of the bidirectional thyristor Q1 is electrically connected to capacitor C4 and then electrically connected to pin 6 of the control chip U1, one end of a fuse resistor FR2 is electrically connected to the first anode of the bidirectional thyristor Q1, the other end of the fuse resistor FR2 is electrically connected to a resistor R10, and the resistor R10 is electrically connected to the gate of the bidirectional thyristor Q1 and capacitor C4 respectively.

6. The circuit for automatically switching input voltage and reducing input loss according to claim 5, characterized in that: The first pin of the control chip U1 is electrically connected to the resistor R13 and then electrically connected to one input end of the photocoupler U2 . The other input end of the photocoupler U2 is electrically connected to the second pin of the control chip U1 .

7. The circuit for automatically switching input voltage and reducing input loss according to claim 6, characterized in that: The energy-saving circuit includes a main energy-saving module composed of a resistor R16, a resistor R17, a resistor R18, a transistor Q3, a diode D6, a resistor R19, a capacitor C9, a resistor R20, a MOS tube Q2, a fuse resistor FR1, and a voltage-stabilizing diode D7. The resistors R16, R17, and R18 are connected in series at the output end of the rectifier bridge DB1, the base of the transistor Q3 is respectively connected to the anodes of the resistor R17, the resistor R18, and the diode D6, the emitter of the transistor Q3 is electrically connected to the resistor R19, the collector of the transistor Q3 is respectively electrically connected to the capacitor C9, the anode of the voltage-stabilizing diode D7, and the source of the MOS tube Q2, the fuse resistor FR1 is electrically connected between the source and the drain of the MOS tube Q2, and the gate of the MOS tube Q2 is respectively electrically connected to the cathode of the voltage-stabilizing diode D7 and the resistor R20.

8. The circuit for automatically switching input voltage and reducing input loss according to claim 7, characterized in that: The emitter of the photoelectric coupler U2 is electrically connected to resistors R14 and R15 and then grounded. The emitter of the photoelectric coupler U2 is electrically connected to resistor R14 and then electrically connected to the gate of the MOS tube Q2, resistor R20, and the cathode of the diode D7. The resistors R1, R2, and R3 are connected in series at the output end of the rectifier bridge DB1. The resistor R3 is electrically connected to the collector of the photoelectric coupler U2. The collector of the photoelectric coupler U2 is also electrically connected to the cathode of the voltage-stabilizing diode D5 and capacitor C8, respectively. The anode of the diode D5, the capacitor C8, and the resistor R18 are electrically connected.

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