A PWM circuit based on capacitor voltage reduction, packaging module and device

Abstract

The application relates to the technical field of circuits, and provides a PWM type circuit based on capacitor voltage reduction, a packaging module and equipment.The circuit comprises a rectifying module, a logic control module, a power conversion module and an output module, wherein one end of the rectifying module is connected with high-voltage alternating current voltage, and the other end outputs pulsating direct current voltage; the logic control module and the internal sampling, comparison and timing function circuits of the power conversion module realize logic control of charging and discharging of an energy capacitor in a set and controllable voltage range, and output low-voltage direct current voltage; and the output module is a pulse width modulator, which outputs a target direct current voltage after voltage stabilization processing.The application provides a lower input voltage for a non-isolated voltage reduction in a later stage by controlling the charge of an energy storage capacitor, so that a large transformation ratio voltage reduction of input and output is realized without using a transformer, and meanwhile, it is possible to realize modularization packaging of an AC-DC large transformation ratio circuit.

Description

Technical Field

[0001] This invention relates to the field of electronic circuits, and more particularly to a PWM circuit, package module and device based on capacitor step-down. Background Technology

[0002] AC to DC power conversion circuits are widely used in home appliances, communications, power electronics, and various embedded devices. Existing AC / DC step-down conversion technologies mainly employ two methods: transformer-isolated and non-isolated. In scenarios with a large input-output voltage conversion ratio, a low-frequency transformer typically steps down the high-voltage AC to the required range, then converts it to DC via bridge rectification and capacitor filtering. Alternatively, when high-precision voltage conversion (e.g., 220V AC to 5V DC) is required, rectification and capacitor filtering typically yield a 310V DC voltage, which is then stepped down using a high-ratio transformer for isolation, and further regulated by a voltage regulator circuit. While these solutions are mature, they suffer from large size, high cost, and complex design. The bulky transformers also pose challenges for modular circuit packaging, especially in applications requiring low power and low voltage output (e.g., below 3.3VDC). This not only results in low efficiency but also necessitates numerous external components, hindering circuit miniaturization and integration.

[0003] In existing AC / DC conversion schemes, the rectified and filtered DC voltage is approximately √2 times the effective value of the input AC voltage. This necessitates a high switching frequency and an extremely low duty cycle when operating at high voltage input and low voltage output, resulting in complex circuit design, reduced efficiency, limited component selection, and decreased reliability. Therefore, how to achieve a low-power AC-DC conversion circuit with high efficiency and low cost over a wide input voltage range has become an urgent problem to be solved. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a PWM circuit, package module and device based on capacitor step-down, which achieves safe voltage reduction and stable power supply by controlling the charge of the energy storage capacitor. It solves the problems of traditional AC / DC step-down circuits requiring low duty cycle and high switching frequency, which leads to reduced circuit efficiency and limited device selection. It realizes direct and efficient conversion of AC power supply to low-voltage DC power supply, and at the same time makes it possible to realize modular packaging of AC-DC high-ratio circuits.

[0005] In a first aspect, embodiments of the present invention provide a PWM circuit based on capacitor-based voltage reduction, characterized in that the circuit includes a rectification module, a logic control module, a power conversion module, and an output module, wherein... One end of the rectifier module is connected to a high-voltage AC voltage, and the other end outputs a pulsating DC voltage; The logic control module receives a pulsating DC voltage from the rectifier module at one end and is connected to a capacitor at the other end. The logic control module is used to control the circuit to charge the capacitor when the pulsating DC voltage is within a preset voltage range. One end of the power conversion module is connected to a capacitor, and the other end outputs a low-voltage DC voltage. The output module is a pulse width modulator. The input terminal of the output module receives a low-voltage DC voltage from the power conversion module and outputs a regulated target DC voltage.

[0006] Preferably, the logic control module includes a voltage divider module, a comparison and detection module, a timing module, a logic module, a controlled switch module, and a protection module, wherein... The voltage divider module includes a voltage divider resistor, which is used to divide the high-voltage pulsating DC current into a low-voltage sampling signal; The comparison and detection module includes a comparator for outputting a high / low level based on the comparison result of the low-voltage sampled signal, providing the original level signal for logic control; The timing module includes a D flip-flop for receiving transient raw level signals from the comparison and detection module and latching the transient raw level signals. The logic module includes an XOR gate and a XNOR gate, which are used to perform logical operations on the original level signals from the comparison and detection module and output control signals to control the controlled switch module. The controlled switch module includes a MOSFET and a switch S1, which is used to switch the charging control circuit on and off after receiving a control signal from the logic module. The protection module includes a protection resistor to prevent current from flowing back into the capacitor, thus protecting the device.

[0007] Preferably, the voltage divider resistors in the voltage divider module include resistors R1, R2, R4, R5, R6, R7, and R9, which divide the high-voltage pulsating DC voltage into low-voltage sampling signals. The low-voltage sampling signals are then sent to the input terminals of the comparators in the comparison and detection module.

[0008] Preferably, the comparison and detection module includes several comparators, with a first input terminal receiving a low-voltage sampling signal from the voltage divider module, a second input terminal receiving a reference voltage signal, and an output terminal connected to the timing module to provide the original level signal.

[0009] Preferably, logic gate U4A is an XOR gate and logic gate U5A is an XNOR gate. The XOR gate U4A and the XNOR gate U5A receive the signals output by the D flip-flop, perform logical operations, and output a drive signal for controlling the on / off state of MOS transistor Q2 in the controlled switch module.

[0010] Preferably, the power conversion module includes a main power switching module, a filtering and energy transfer module, and a current detection module, wherein, The main power switch module includes a main switch S2 and a synchronous switch S4, which are used to receive the pulsating DC signal from capacitor C7, perform pulse modulation, and output modulated pulsating current. The filtering and energy transfer module includes an inductor L2 and a capacitor C4. The filtering and energy transfer module receives the modulated pulsating current output from the main power switch module and outputs a filtered pulsating current. The current detection module includes a sampling resistor R14, a test probe U7, and a load resistor, and is used for current detection.

[0011] Preferably, the output module includes a PWM drive module and a voltage feedback and error amplification module, wherein, The PWM drive module includes signal source V8, signal source V6, NOT gate U6A, flip-flop U5, and comparator U2A. The PWM drive module is used to generate PWM signals and drive the main power switch module to work. The voltage feedback and error amplification module includes resistors R10, R17, R19 and comparator U2B, which are used to sample the output voltage and compare it with the reference voltage, and output an error signal to adjust the duty cycle of the PWM signal.

[0012] Preferably, the main power switch module includes a main switch S2 and a synchronous switch S4, wherein, The main switch S2 is periodically turned on and off under the action of the PWM control signal, and the synchronous switch S4 is turned on when the main switch S2 is off.

[0013] Secondly, embodiments of the present invention provide a packaging module, the packaging module including a packaging shell, and the packaging shell encapsulates the PWM type circuit based on capacitor step-down as described in the first aspect.

[0014] Thirdly, embodiments of the present invention provide an electronic device, characterized in that it includes the packaging module described in the second aspect.

[0015] In summary, the beneficial effects of the present invention are as follows: A PWM circuit, packaging module and device based on capacitive voltage reduction solve the technical problems existing in traditional AC / DC step-down circuits under wide input voltage conditions. By controlling the charge of the energy storage capacitor, a relatively low input voltage is provided for the subsequent non-isolated step-down, so that the purpose of achieving a large step-down ratio of input and output voltages can be achieved without using a transformer. At the same time, it makes it possible to modularize the AC-DC large step-down ratio circuit. Through internal sampling, comparison and timing and other functional circuits to control the switch, the logic control of charging and discharging the energy capacitor is realized within a set and controllable voltage range (for example: 70 < VC < 100V), so as to provide a relatively low input voltage for the subsequent stage, improve the duty cycle of the non-isolated BUCK circuit, fundamentally improve the contradiction between high-voltage input and low-voltage output, make it possible to directly convert high-voltage alternating current into low-voltage direct current, greatly simplify the peripheral circuit, reduce the harsh requirements for the withstand voltage and switching frequency of the switching device, and can easily achieve AC / DC power conversion. Only a step-down charging capacitor and an output filter capacitor are required for the periphery to step down 220VAC to 3.3VDC or even lower DC voltage. The overall efficiency of the circuit is improved, the production and application costs are reduced, the design and implementation are more simplified, and it is suitable for scenarios with low power requirements but high efficiency and low cost. Fundamentally improve the contradiction between high-voltage input and low-voltage output. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly introduced below. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings, and these are all within the protection scope of the present invention.

[0017] Figure 1 It is a schematic diagram of the overall design of the PWM circuit based on capacitive voltage reduction of the present invention; Figure 2 It is a schematic diagram of the charging control module of the PWM circuit based on capacitive voltage reduction of the present invention; Figure 3 It is a schematic diagram of the rectification module of the PWM circuit based on capacitive voltage reduction of the present invention; Figure 4 It is a schematic diagram of the voltage division module of the PWM circuit based on capacitive voltage reduction of the present invention; Figure 5 It is a schematic diagram of the comparison and detection module, timing module and logic module of the PWM circuit based on capacitive voltage reduction of the present invention; Figure 6 It is a schematic diagram of the power conversion module and output module of the PWM circuit based on capacitive voltage reduction of the present invention; Figure 7This is a schematic diagram of the output result of the PWM circuit based on capacitor voltage reduction of the present invention when the input AC is 85V; Figure 8 This is a schematic diagram of the output result of the PWM circuit based on capacitor voltage reduction of the present invention when the input AC is 220V; Figure 9 This is a schematic diagram of the output result of the PWM circuit based on capacitor voltage reduction of the present invention when the input AC is 305V. Detailed Implementation

[0018] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present 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 only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0019] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0020] It should be noted that all actions involving the acquisition of signals, information, or data in this invention are carried out in compliance with the relevant data protection laws and regulations of the locality and with authorization from the owner of the relevant device. Example 1

[0021] Please see Figure 1 This invention provides a PWM circuit based on capacitor-based voltage reduction. The circuit includes a rectifier module, a logic control module, a power conversion module, and an output module. One end of the rectifier module is connected to a high-voltage AC voltage, and the other end outputs a pulsating DC voltage; The logic control module receives a pulsating DC voltage from the rectifier module at one end and is connected to a capacitor at the other end. The logic control module is used to control the circuit to charge the capacitor when the pulsating DC voltage is within a preset voltage range. One end of the power conversion module is connected to a capacitor, and the other end outputs a low-voltage DC voltage. The output module is a pulse width modulator. The input terminal of the output module receives a low-voltage DC voltage from the power conversion module and outputs a regulated target DC voltage.

[0022] For details, see Figure 2 The output of the rectifier module is connected to the input of the logic control module. After rectification, instead of directly connecting a large electrolytic capacitor for smoothing and filtering, the pulsating DC is sent directly to the logic control module. The logic control within the module then selects an appropriate voltage range to charge the capacitor. The rectifier module is a full-bridge rectifier; the high-voltage AC output from the power supply is rectified by the full-bridge rectifier to obtain a pulsating DC voltage, which then enters the logic control module. See also... Figure 3 The rectifier module includes diodes D1, D2, D5, and D6, all of which are D1N4007 type. The high-voltage AC voltage is rectified by the four diodes in a full-bridge rectifier to obtain pulsating DC, providing the input voltage for the subsequent logic control module. The four diodes form a rhombus structure. Only two of the diodes on opposite sides of the rhombus conduct at any given time, converting the AC to pulsating DC. When the AC is in the positive half-cycle, one pair of diodes on opposite sides of the rhombus conducts, allowing current to flow from the VAC input through the diodes. When the AC is in the negative half-cycle, the other pair of diodes conducts, and the current still flows from the right side to ground, ensuring a constant output voltage direction.

[0023] After passing through the voltage divider resistors in the logic control module, a voltage threshold range of 30V~70V is obtained. After passing through the two comparators of U1 and the subsequent D flip-flop, a corresponding pulse square wave signal is obtained. After being converted into a drive control signal by Q2, it drives S1 to charge and filter the subsequent capacitor.

[0024] The pulsating DC current enters the logic control module. After passing through a voltage divider resistor, a voltage threshold range of 30V~70V is obtained. This voltage is then processed by a comparator and a flip-flop to generate a corresponding pulsed square wave signal. After level conversion, this signal is converted into a drive control signal, which closes the switch, causing the subsequent capacitor to charge and filter. Through internal sampling, comparison, and timing circuitry, the switch control enables logic control of charging and discharging the energy capacitor within a set and controllable voltage range. This provides a relatively low input voltage to the subsequent stage, increasing the duty cycle of the non-isolated BUCK circuit.

[0025] In one embodiment, the logic control module includes a voltage divider module, a comparison and detection module, a timing module, a logic module, a controlled switch module, and a protection module, wherein, The voltage divider module includes a voltage divider resistor, which is used to divide the high-voltage pulsating DC current into a low-voltage sampling signal; The comparison and detection module includes a comparator for outputting a high / low level based on the comparison result of the low-voltage sampled signal, providing the original level signal for logic control; The timing module includes a D flip-flop for receiving transient raw level signals from the comparison and detection module and latching the transient raw level signals. The logic module includes an XOR gate and a XNOR gate, which are used to perform logical operations on the original level signals from the comparison and detection module and output control signals to control the controlled switch module. The controlled switch module includes a MOSFET and a switch S1, which is used to switch the charging control circuit on and off after receiving a control signal from the logic module. The protection module includes a protection resistor to prevent current from flowing back into the capacitor, thus protecting the device.

[0026] Specifically, the voltage divider module, comparison and detection module, timing module, logic module, controlled switch module, and protection module work together to achieve safe sampling, comparison, logic processing, and controlled switch control of high-voltage pulsating DC signals. The voltage divider module divides the high voltage into a safe low level for comparison by the subsequent comparison and detection module. The comparison and detection module consists of a comparator and a reference voltage source, used to compare the low-voltage sampled signal with the reference voltage source to obtain the original level signal. The timing module includes a D flip-flop, used to receive the transient original level signal output by the comparator and latch it on the clock edge to ensure the output signal is stable and has a minimum pulse width. The logic module includes XOR gates and XNOR gates, used to perform logical operations on multiple original level signals and the reference voltage source to form a control signal that conforms to the control strategy. The controlled switch module includes a MOSFET and switch S1, which realizes circuit on / off switching after receiving the control signal output by the logic module. When S1 is closed, capacitor C7 charges; when S1 is open, capacitor C7 stops charging. The protection module includes a protection resistor, used to prevent capacitor energy from flowing back into the front-end circuit in the event of circuit shutdown or abnormal conditions, thereby protecting the logic gates, comparator, voltage divider resistors, and rectifier bridge from damage. It can also work with current limiting, diodes, or TVS suppression devices to achieve surge protection and safe discharge. The overall design achieves safe conversion of high-voltage signals to low-voltage logic and controlled energy management through the organic combination of voltage division, comparison, latching, logic operation and power switch control. It features fast response, strong anti-interference ability and safety and reliability.

[0027] In one embodiment, the voltage divider module includes resistors R1, R2, R4, R5, R6, R7, and R9, which divide the high-voltage pulsating DC voltage into low-voltage sampling signals. The low-voltage sampling signals are then sent to the input terminals of the comparators in the comparison and detection module.

[0028] For details, see Figure 2 and Figure 4 The voltage divider module includes resistors R11, R2, R4, R9, R1, R5, R6, and R7. One end of resistor R11 is connected to the output terminal of the rectifier module, and the other end is connected to resistor R2. Resistors R2, R4, and R9 are connected in series between resistor R11 and ground. One end of resistor R2 is connected to resistor R11, and the other end is connected to the positive input terminal of comparator U1A in the comparison and detection module. The node between resistors R4 and R9 is connected to the positive input terminal of comparator U1B in the comparison and detection module. One end of capacitor C2 is connected to the positive terminal of the reference voltage source V7, and the other end is grounded. Similarly, one end of capacitor C3 is connected to the positive terminal of the reference voltage source V7, and the other end is grounded.

[0029] Resistor R1 and resistor R5 are connected in series between the reference voltage source V7 and ground. One end of resistor R1 is connected to the positive terminal of the reference voltage source V7, and the other end is connected to one end of resistor R5 and the negative input terminal of comparator U1A. The other end of resistor R5 is grounded. Resistor R7 and resistor R6 are connected in series between the reference voltage source V7 and ground. One end of resistor R7 is connected to the positive terminal of the reference voltage source V7, and the other end is connected to one end of resistor R6 and the negative input terminal of comparator U1B. The other end of resistor R6 is grounded. Comparators U1A and U1B are both LM358. One end of resistor R3 is connected to the positive terminal of the reference voltage source V7, and the other end is grounded after passing through capacitor C5.

[0030] In one embodiment, the comparison and detection module includes several comparators, a first input terminal receiving a low-voltage sampling signal from the voltage divider module, a second input terminal receiving a reference voltage signal, and an output terminal connected to the timing module to provide the original level signal.

[0031] Specifically, the output of comparator U1A is connected to the CLK pin of D flip-flop U3A in the timing module. The D pin of D flip-flop U3A is connected to the QN pin, and the Q pin of D flip-flop U3A is connected to the first input of XOR gate U4A and the first input of XNOR gate U9A in the logic module. The output of comparator U1B is connected to the CLK pin of D flip-flop U3B in the timing module. The D pin of D flip-flop U3B is connected to the QN pin, and then connected to the second input of XOR gate U4A and the second input of XNOR gate U9A in the logic module. Both D flip-flops U3A and U3B are model 74HC74, XOR gate U4A is model CD4070B, and XNOR gate U9A is model CD4077B.

[0032] In one embodiment, logic gate U4A is an XOR gate and logic gate U5A is an XNOR gate. The XOR gate U4A and the XNOR gate U5A receive the signals output by the D flip-flop, perform logical operations, and output a drive signal for controlling the on / off state of the MOS transistor Q2 in the controlled switch module.

[0033] For details, see Figure 2 and Figure 5 The XOR gate U4A, model CD4070B, receives the latch signal from the D flip-flop in the timing module. It outputs a high level when the two input signals are different and a low level when the two input signals are the same. The XNOR gate U5A, model CD4077B, receives the latch signal from the timing module. Its logic is the opposite of the XOR gate; it outputs a high level when the two input signals are the same and a low level when the two input signals are different.

[0034] It performs a logical XOR operation to generate a control signal, which controls the actions of subsequent controlled switching modules, such as adjusting the on and off timing of the switches, thereby affecting the charging and discharging process of the capacitor. Its function is to generate another control signal by performing an XOR operation on these two types of signals. This signal, in conjunction with the signal output from the XOR gate, enables more complex and precise logical control of the various modules in the circuit, ensuring the orderly operation of functions such as capacitor voltage reduction and PWM voltage regulation.

[0035] In one embodiment, the power conversion module includes a main power switching module, a filtering and energy transfer module, and a current detection module, wherein, The main power switch module includes a main switch S2 and a synchronous switch S4, which are used to receive the pulsating DC signal from capacitor C7, perform pulse modulation, and output modulated pulsating current. The filtering and energy transfer module includes an inductor L2 and a capacitor C4. The filtering and energy transfer module receives the modulated pulsating current output from the main power switch module and outputs a filtered pulsating current. The current detection module includes a sampling resistor R14, a test probe U7, and a load resistor, and is used for current detection.

[0036] Specifically, such as Figure 6 As shown, V_cap is a relatively smooth DC voltage of approximately 70V, which serves as the input voltage. This input voltage is stepped down by a BUCK circuit consisting of the main switch S2, synchronous switch S4, and inductor L2 to obtain the desired output voltage. This circuit employs a voltage control loop to ensure stable output. The clock and triangular wave are provided by a signal generator at a frequency of 700kHz. When the PWM signal is high, the main switch S2 is turned on, connecting the input voltage to inductor L2, which then flows through capacitor C4 into the subsequent load circuit. When the main switch S2 is open, the synchronous switch S4 is closed, allowing the inductor current to freewheel through the S4 loop.

[0037] The sampling resistor R14 has a resistance of 0.0001Ω, which generates a very small voltage drop when current flows through it. This voltage is collected by the subsequent detection circuit for current detection / overcurrent protection. The test probe U7 is used for current measurement, and resistors R12 and R24 are grounded as the load of the detection node.

[0038] In one embodiment, the output module includes a PWM drive module and a voltage feedback and error amplification module, wherein, The PWM drive module includes signal source V8, signal source V6, NOT gate U6A, flip-flop U5, and comparator U2A. The PWM drive module is used to generate PWM signals and drive the main power switch module to work. The voltage feedback and error amplification module includes resistors R10, R17, R19 and comparator U2B, which are used to sample the output voltage and compare it with the reference voltage, and output an error signal to adjust the duty cycle of the PWM signal.

[0039] Specifically, the triangular wave signal source V8 generates a periodic triangular wave at a fixed frequency, serving as the carrier reference. The square wave clock signal source V6 outputs a clock pulse consistent with the system switching frequency. After level shaping by the NOT gate U6A, the pulse is sent to the flip-flop U5. The flip-flop latches the input pulse and suppresses glitches, ensuring stable timing for subsequent comparison and driving processes. One end of the comparator U2A receives the error signal from the voltage feedback and error amplification module, while the other end receives the triangular wave signal. When the error signal is higher than the instantaneous voltage of the triangular wave, the comparator U2A outputs a high level; when the error signal is lower than the instantaneous voltage of the triangular wave, the comparator U2A outputs a low level, thus obtaining a PWM square wave with a duty cycle that continuously varies with the amplitude of the error signal. This PWM square wave is shaped and isolated by the driver stage and then sent to the main switch S2 to complete the duty cycle modulation of the power stage. The DC voltage at the output terminal is divided into a low-voltage sampling signal by voltage divider resistors R17 and R1. This sampling signal is input to one end of the comparator U2B, and the other end is connected to the reference voltage source V9. Comparator U2B compares and amplifies the difference between the sampled voltage and the reference voltage, generating an error signal reflecting the direction and amplitude of the output deviation. To ensure closed-loop stability and set the system's low-frequency gain and high-frequency roll-off, a compensation network consisting of R18, R20, R21, C6, C8, and C9 is connected between the output and input of U2B. This network provides sufficient integration in the low-frequency range to eliminate steady-state error and provides phase margin in the mid-to-high-frequency range to suppress oscillation. Under light load conditions, to avoid unstable sampling or the error amplifier entering the nonlinear region due to a floating output, a small static load can be provided by R10 to keep sampling and compensation within the linear operating range. The compensated error signal is output to comparator U2A in the PWM generation and drive module to adjust the PWM duty cycle.

[0040] In one embodiment, the main power switch module includes a main switch S2 and a synchronous switch S4, wherein, The main switch S2 is periodically turned on and off under the action of the PWM control signal, and the synchronous switch S4 is turned on when the main switch S2 is off.

[0041] Specifically, when the main switch S2 is turned on by a high-level PWM signal, the DC voltage provided by the input capacitor is applied to the inductor L2 via S2, causing the inductor to absorb energy and raise the output voltage. When the PWM signal is low and S2 is turned off, the synchronous switch S4 freewheels, releasing energy to the output capacitor and load, thus maintaining the output voltage and achieving filtering. As the voltage feedback and error amplification modules change the amplitude of the error signal in real time, the PWM generation and drive modules correspondingly change the duty cycle of S2, adjusting the energy absorption and discharge time of the power stage accordingly, and stabilizing the output voltage near the target value set by the reference voltage. Example 2

[0042] An embodiment of the present invention provides a packaging module, which includes a packaging shell, and the PWM type circuit based on capacitive buck described in Embodiment 1 is packaged inside the packaging shell. Embodiment 3

[0043] An embodiment of the present invention provides an electronic device, which includes the packaging module described in Embodiment 2.

[0044] In summary, the beneficial effects of a PWM type circuit, a packaging module and a device based on capacitive buck provided in this embodiment are as follows: On the one hand, the circuit can work stably within a wide AC voltage range, significantly improving the adaptability and application range of the circuit; on the other hand, due to reducing the stringent requirements for the withstand voltage and switching frequency of the switching device, the overall efficiency of the circuit is improved, the production and application costs are reduced, and the design implementation is more simplified, which is suitable for scenarios with low power requirements but high efficiency and low cost.

[0045] A PWM type circuit, a packaging module and a device based on capacitive buck provided by the present invention, after the AC power supply is connected and rectified by a full-bridge rectifier, instead of directly obtaining a smooth DC voltage through capacitor filtering as in the traditional scheme, it samples the rectified pulsating DC voltage, and through logic control, it selects to charge and filter the capacitor in the voltage range of 30V to 70V, so as to provide a suitable input voltage for the subsequent Buck type switching power supply. Through internal sampling, comparison and timing and other functional circuits, through the control of the switch, the logical control of charging and discharging the energy capacitor is realized within a set and controllable voltage range (for example: 70 < VC < 100V), so as to provide a relatively low input voltage for the subsequent stage, and improve the duty cycle of the non-isolated BUCK circuit. This method effectively avoids the technical problems such as low duty cycle and high switching frequency that inevitably appear between high-voltage input and low-voltage output due to full-bridge rectification plus capacitor filtering in common AC-DC circuits; while ensuring a wide input and output range, the production and application costs are reduced as much as possible. However, this circuit also has certain limitations: its output power is relatively small, and due to its non-isolated structure, its safety is insufficient compared with isolated circuits.

[0046] Convert high-voltage input into low-voltage output and reduce the dependence on high-frequency switching devices. The circuit structure is clear, the modularity is high, and it is convenient to realize chip or modular packaging. The peripheral circuit is simple, and only a buck capacitor and a filter capacitor are needed to obtain a stable DC output.

[0047] The above description is merely a specific embodiment of the present invention. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A PWM circuit based on capacitor-based voltage reduction, characterized in that, The circuit includes a rectifier module, a logic control module, a power conversion module, and an output module, wherein... One end of the rectifier module is connected to a high-voltage AC voltage, and the other end outputs a pulsating DC voltage; The logic control module receives a pulsating DC voltage from the rectifier module at one end and is connected to a capacitor at the other end. The logic control module is used to control the circuit to charge the capacitor when the pulsating DC voltage is within a preset voltage range. One end of the power conversion module is connected to a capacitor, and the other end outputs a low-voltage DC voltage. The output module is a pulse width modulator. The input terminal of the output module receives a low-voltage DC voltage from the power conversion module and outputs a regulated target DC voltage.

2. The PWM circuit based on capacitor-based voltage reduction according to claim 1, characterized in that, The logic control module includes a voltage divider module, a comparison and detection module, a timing module, a logic module, a controlled switch module, and a protection module, wherein... The voltage divider module includes a voltage divider resistor, which is used to divide the high-voltage pulsating DC current into a low-voltage sampling signal; The comparison and detection module includes a comparator for outputting a high / low level based on the comparison result of the low-voltage sampled signal, providing the original level signal for logic control; The timing module includes a D flip-flop for receiving transient raw level signals from the comparison and detection module and latching the transient raw level signals. The logic module includes an XOR gate and a XNOR gate, which are used to perform logical operations on the original level signals from the comparison and detection module and output control signals to control the controlled switch module. The controlled switch module includes a MOSFET and a switch S1, which is used to switch the charging control circuit on and off after receiving a control signal from the logic module. The protection module includes a protection resistor to prevent current from flowing back into the capacitor, thus protecting the device.

3. The PWM circuit based on capacitor-based voltage reduction according to claim 2, characterized in that, The voltage divider module includes resistors R1, R2, R4, R5, R6, R7, and R9, which divide the high-voltage pulsating DC voltage into low-voltage sampling signals. The low-voltage sampling signals are then sent to the input terminals of the comparators in the comparison and detection module.

4. The PWM circuit based on capacitor-based voltage reduction according to claim 2, characterized in that, The comparison and detection module includes several comparators. The first input terminal receives the low-voltage sampling signal from the voltage divider module, the second input terminal receives the reference voltage signal, and the output terminal is connected to the timing module to provide the original level signal.

5. The PWM circuit based on capacitor-based voltage reduction according to claim 2, characterized in that, The logic gate U4A is an XOR gate and the logic gate U5A is an XNOR gate. The XOR gate U4A and the XNOR gate U5A receive the signals output by the D flip-flop, perform logic operations, and output a drive signal to control the on / off state of the MOS transistor Q2 in the controlled switch module.

6. The PWM circuit based on capacitor-based voltage reduction according to claim 1, characterized in that, The power conversion module includes a main power switching module, a filtering and energy transfer module, and a current detection module, wherein... The main power switch module includes a main switch S2 and a synchronous switch S4, which are used to receive the pulsating DC signal from capacitor C7, perform pulse modulation, and output modulated pulsating current. The filtering and energy transfer module includes an inductor L2 and a capacitor C4. The filtering and energy transfer module receives the modulated pulsating current output from the main power switch module and outputs a filtered pulsating current. The current detection module includes a sampling resistor R14, a test probe U7, and a load resistor, and is used for current detection.

7. The PWM circuit based on capacitor-based voltage reduction according to claim 61, characterized in that, The output module includes a PWM drive module and a voltage feedback and error amplification module, wherein, The PWM drive module includes signal source V8, signal source V6, NOT gate U6A, flip-flop U5, and comparator U2A. The PWM drive module is used to generate PWM signals and drive the main power switch module to work. The voltage feedback and error amplification module includes resistors R10, R17, R19 and comparator U2B, which are used to sample the output voltage and compare it with the reference voltage, and output an error signal to adjust the duty cycle of the PWM signal.

8. The PWM circuit based on capacitor-based voltage reduction according to claims 6-7, characterized in that, The main power switch module includes a main switch S2 and a synchronous switch S4, wherein... The main switch S2 is periodically turned on and off under the action of the PWM control signal, and the synchronous switch S4 is turned on when the main switch S2 is off.

9. A packaging module, characterized in that, The packaging module includes a packaging shell, and the packaging shell encapsulates a PWM type circuit based on capacitor step-down as described in any one of claims 1-8.

10. An electronic device, characterized in that, Includes the encapsulation module as described in claim 9.

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