CN117977980A - Flyback switching power supply - Google Patents
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
- H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
- H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
- H02M7/06—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of DC power input into DC power output
- H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
- H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
- H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
- H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33507—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
本发明公开了一种反激式开关电源，包括：整流滤波电路，用于将输入的85V‑260V交流电转换为24V正向脉动的直流电；EMI电路，用于减少外部环境岁整流滤波后的24V正向脉动的直流电的电磁干扰；RCD钳位电路，用于限制RCD在动作时的电压尖峰，防止由于电流突然切断而在电路中产生过压；变压器模块，用于将24V正向脉动的直流电转化为交流的PWM信号；输出整流电路，用于将交流的PWM信号转换为稳定的12V直流信号；控制电路，用于监测变压器模块的电压调整过程，并根据监测生成用于调节电路系统的操作信号，本申请的反激式开关电源使用混合调制技术，提高了芯片的转换效率。
The present invention discloses a flyback switching power supply, comprising: a rectifier and filter circuit, used for converting an input 85V-260V alternating current into a 24V forward pulsating direct current; an EMI circuit, used for reducing the electromagnetic interference of the 24V forward pulsating direct current after rectification and filtering in the external environment; an RCD clamping circuit, used for limiting the voltage spike of the RCD when it is in action, and preventing overvoltage from being generated in the circuit due to sudden current cut-off; a transformer module, used for converting the 24V forward pulsating direct current into an alternating current PWM signal; an output rectifier circuit, used for converting the alternating current PWM signal into a stable 12V direct current signal; a control circuit, used for monitoring the voltage adjustment process of the transformer module, and generating an operation signal for adjusting the circuit system according to the monitoring. The flyback switching power supply of the present application uses a hybrid modulation technology to improve the conversion efficiency of the chip.
Description
技术领域Technical Field
本发明涉及开关电源技术领域，尤其涉及一种反激式开关电源。The present invention relates to the technical field of switching power supplies, and in particular to a flyback switching power supply.
背景技术Background technique
目前传统的反激式电源采用的是SSR技术(光耦技术)，但是存在以下缺点：首先是成本问题，虽然光耦反激式电源的成本相对较低，但相较于其他类型的电源，其成本可能略高，尤其是在大规模应用时。其次是光耦合器可靠性问题：光耦合器在长时间工作过程中可能会因为温度的变化、灰尘的侵入等因素影响其性能和可靠性。At present, the traditional flyback power supply adopts SSR technology (optocoupler technology), but it has the following disadvantages: First, the cost issue. Although the cost of the optocoupler flyback power supply is relatively low, it may be slightly higher than other types of power supplies, especially in large-scale applications. The second is the reliability of the optocoupler: the performance and reliability of the optocoupler may be affected by factors such as temperature changes and dust intrusion during long-term operation.
还有电气隔离限制问题：虽然光耦合器提供了电气隔离，但在某些应用中，这种隔离可能不足以满足安全和防干扰的要求。同时光耦式反激电源存在保护功能限制：光耦合器的反馈机制可能不足以提供快速有效的保护，如过载保护、短路保护等，这可能需要额外的电路保护措施。最后是效率问题：虽然反激式开关电源整体效率较高，但在某些情况下，如果设计不当，可能会导致效率降低，特别是开关损耗和磁性元件的磁滞损耗。There is also the issue of electrical isolation limitations: Although optocouplers provide electrical isolation, in some applications, this isolation may not be sufficient to meet safety and anti-interference requirements. At the same time, optocoupler flyback power supplies have protection function limitations: the feedback mechanism of the optocoupler may not be sufficient to provide fast and effective protection, such as overload protection, short-circuit protection, etc., which may require additional circuit protection measures. Finally, there is the issue of efficiency: Although the overall efficiency of the flyback switching power supply is high, in some cases, if the design is improper, it may lead to reduced efficiency, especially switching losses and hysteresis losses of magnetic components.
发明内容Summary of the invention
为解决背景技术中存在的技术问题，本发明提出一种反激式开关电源。In order to solve the technical problems existing in the background technology, the present invention provides a flyback switching power supply.
本发明提出的一种反激式开关电源，包括：A flyback switching power supply proposed by the present invention comprises:
整流滤波电路，用于将输入的85V-260V交流电转换为24V正向脉动的直流电；The rectifier filter circuit is used to convert the input 85V-260V AC power into 24V positive pulsating DC power;
EMI电路，用于减少外部环境岁整流滤波后的24V正向脉动的直流电的电磁干扰；EMI circuit, used to reduce the electromagnetic interference of the 24V positive pulsating DC power after rectification and filtering in the external environment;
RCD钳位电路，用于限制RCD在动作时的电压尖峰，防止由于电流突然切断而在电路中产生过压；RCD clamping circuit is used to limit the voltage spike when the RCD is in action, to prevent overvoltage in the circuit due to sudden current cut-off;
变压器模块，用于将24V正向脉动的直流电转化为交流的PWM信号；Transformer module, used to convert 24V positive pulsating DC power into AC PWM signal;
输出整流电路，用于将交流的PWM信号转换为稳定的12V直流信号；Output rectifier circuit, used to convert the AC PWM signal into a stable 12V DC signal;
控制电路，用于监测变压器模块的电压调整过程，并根据监测生成用于调节电路系统的操作信号；A control circuit, used for monitoring the voltage regulation process of the transformer module and generating an operation signal for regulating the circuit system according to the monitoring;
其中，整流滤波电路的输出端与EMI电路的输入端电性连接；EMI电路的输出端与RCD钳位电路的输入端电性连接；RCD钳位电路的输出端与变压器的输入端电性连接；变压器模块的输出端与输出整流电路的输入端电性连接；RCD钳位电路的输出端与控制电路的输入端电性连接；控制电路的输入端与变压器模块的输入端电性连接。Among them, the output end of the rectifier and filter circuit is electrically connected to the input end of the EMI circuit; the output end of the EMI circuit is electrically connected to the input end of the RCD clamping circuit; the output end of the RCD clamping circuit is electrically connected to the input end of the transformer; the output end of the transformer module is electrically connected to the input end of the output rectifier circuit; the output end of the RCD clamping circuit is electrically connected to the input end of the control circuit; the input end of the control circuit is electrically connected to the input end of the transformer module.
优选地，还包括：突入浪涌抑制电路，用于提供过电压保护，防止由于电压浪涌而导致的设备损坏。Preferably, it also includes: an inrush surge suppression circuit for providing overvoltage protection to prevent equipment damage caused by voltage surges.
优选地，RCD钳位电路具体包括电阻R1、电容C6、电阻R3、二极管D5，电阻R1与电容C6并联后与电阻R3的一端串联，电阻R3的另一端与二极管D5的负极电性连接。Preferably, the RCD clamp circuit specifically includes a resistor R1, a capacitor C6, a resistor R3, and a diode D5. The resistor R1 is connected in parallel with the capacitor C6 and then connected in series with one end of the resistor R3. The other end of the resistor R3 is electrically connected to the cathode of the diode D5.
优选地，变压器模块的初级线圈与RCD钳位电路相连，以接收24V正向脉动的直流电，变压器模块的一组次级线圈连接控制电路并接地，变压器模块的另一组次级线圈连接输出整流电路。Preferably, the primary coil of the transformer module is connected to the RCD clamping circuit to receive 24V positive pulsating DC power, a set of secondary coils of the transformer module is connected to the control circuit and grounded, and another set of secondary coils of the transformer module is connected to the output rectifier circuit.
优选地，控制电路包括电源管理模块NCP1239、电解电容C5、电阻R4、电阻R5、电阻R6、电阻R7、电阻R8、电阻R9、二极管D7，电阻R6与电阻R7并联后的一端与电源管理模块NCP1239的FB引脚电性连接；电阻R8、电阻R9并联后的一端与电源管理模块NCP1239的CS引脚电性连接；电源管理模块NCP1239的CS引脚与电源管理模块NCP1239的GND引脚共地；电源管理模块NCP1239的FB引脚与电阻R5的一端电性连接，电阻R5的另一端与二极管D7的正极电性连接；电源管理模块NCP1239的VCC引脚与电阻R4的一端电性连接，电阻R4的另一端与二极管D7的负极电性连接；电阻R4的一端与电解电容C5的正极电性连接；电源管理模块NCP1239的DRV引脚与二极管D5的正极电性连接。Preferably, the control circuit includes a power management module NCP1239, an electrolytic capacitor C5, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, and a diode D7, wherein one end of the resistor R6 and the resistor R7 connected in parallel is electrically connected to the FB pin of the power management module NCP1239; one end of the resistor R8 and the resistor R9 connected in parallel is electrically connected to the CS pin of the power management module NCP1239; and the CS pin of the power management module NCP1239 is electrically connected to the power management module NCP1239. The GND pins of 239 are grounded; the FB pin of the power management module NCP1239 is electrically connected to one end of the resistor R5, and the other end of the resistor R5 is electrically connected to the positive electrode of the diode D7; the VCC pin of the power management module NCP1239 is electrically connected to one end of the resistor R4, and the other end of the resistor R4 is electrically connected to the negative electrode of the diode D7; one end of the resistor R4 is electrically connected to the positive electrode of the electrolytic capacitor C5; the DRV pin of the power management module NCP1239 is electrically connected to the positive electrode of the diode D5.
优选地，突入浪涌抑制电路包括保险丝和压敏电阻，压敏电阻与整流滤波电路并联后串接保险丝。Preferably, the inrush surge suppression circuit comprises a fuse and a varistor, and the varistor is connected in parallel with the rectifier and filter circuit and then in series with the fuse.
本发明中，所提出的反激式开关电源，芯片基于峰值电流控制使系统具有较快的环路响应速度，它的工作模式为DCM，使用混合调制技术来提高芯片的转换效率，使得芯片在整个带载范围内都要着很高的转换效率，控制电路芯片未使用光耦器件，减少了外围电路研发的工作量，同时该芯片控制系统更加的轻巧，相应地减低了其成本。此款开关电源芯片系统拥有较长的使用寿命、较高的可靠性和较强的稳定性等优势，同时可以对此款开关电源系统不再使用光耦器件，进而节约了成本。此外，控制电源芯片内部不系统中又设计了保护电路，从而使芯片处于正常的工作状态，进一步使电路的可靠性获得提升。首先是高效率：本专利设计的反激电源具有较高的效率，尤其是在低负载条件下，因为开关器件在低负载时工作在开关频率较低的状态，从而降低了开关损耗。其次式设计简单：相比其他模式的反激电源，其电路设计相对简单，磁性元件(如变压器)的设计也较为容易。同时拥有较低的成本：由于设计简单，反激电源的生产成本相对较低，适用于成本敏感的应用。最后是其具有良好的电压和负载调节性能，能够提供稳定的输出电压，即使在外部条件变化时也能够保持输出稳定。In the present invention, the proposed flyback switching power supply chip has a faster loop response speed based on peak current control. Its working mode is DCM, and hybrid modulation technology is used to improve the conversion efficiency of the chip, so that the chip has a high conversion efficiency in the entire load range. The control circuit chip does not use optocouplers, which reduces the workload of peripheral circuit research and development. At the same time, the chip control system is more lightweight, and its cost is correspondingly reduced. This switching power supply chip system has the advantages of longer service life, higher reliability and stronger stability. At the same time, optocouplers can no longer be used for this switching power supply system, thereby saving costs. In addition, a protection circuit is designed in the control power supply chip system, so that the chip is in a normal working state, and the reliability of the circuit is further improved. First, high efficiency: the flyback power supply designed by this patent has higher efficiency, especially under low load conditions, because the switching device works in a state of lower switching frequency at low load, thereby reducing switching losses. Secondly, the design is simple: compared with other modes of flyback power supplies, its circuit design is relatively simple, and the design of magnetic components (such as transformers) is also relatively easy. At the same time, it has lower costs: due to the simple design, the production cost of the flyback power supply is relatively low, which is suitable for cost-sensitive applications. Finally, it has good voltage and load regulation performance, can provide a stable output voltage, and can maintain output stability even when external conditions change.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
图1为本发明提出的一种反激式开关电源的系统结构示意图；FIG1 is a schematic diagram of the system structure of a flyback switching power supply proposed by the present invention;
图2为本发明提出的一种反激式开关电源的电压波形变化结构示意图一；FIG2 is a schematic diagram of a voltage waveform variation structure of a flyback switching power supply proposed by the present invention;
图3为本发明提出的一种反激式开关电源的电压波形变化结构示意图二；FIG3 is a second schematic diagram of a voltage waveform variation structure of a flyback switching power supply proposed by the present invention;
图4为本发明提出的一种反激式开关电源的电路的结构示意图。FIG. 4 is a schematic diagram of the structure of a flyback switching power supply circuit proposed by the present invention.
具体实施方式Detailed ways
参照图1-4，本发明提出的一种反激式开关电源，包括：1-4 , a flyback switching power supply proposed by the present invention includes:
整流滤波电路，用于将输入的85V-260V交流电转换为24V正向脉动的直流电。The rectifier and filter circuit is used to convert the input 85V-260V AC power into 24V positive pulsating DC power.
在本实施例中，如图4所示，输入的85V-260V交流电经过整流滤波后，由正弦波变为仅包含正半周的电压波形，整流滤波电路的技术指标主要有最大平均正向整流输出电流-最大反向击穿电压和最大直流阻断电压。其中，In this embodiment, as shown in FIG4 , the input 85V-260V AC power is transformed from a sine wave into a voltage waveform containing only the positive half cycle after rectification and filtering. The technical indicators of the rectification and filtering circuit mainly include the maximum average forward rectified output current-maximum reverse breakdown voltage and maximum DC blocking voltage. Among them,
a.最大平均正向整流输出电流a. Maximum average forward rectified output current
该参数的计算公式为：The calculation formula for this parameter is:
其中，5是安全系数，选择最大平均正向整流输出电流为1A的器件。Where 5 is the safety factor, select a device with a maximum average forward rectified output current of 1A.
b.最大反向击穿电压b. Maximum reverse breakdown voltage
该参数的计算公式为：The calculation formula for this parameter is:
其中，1.25内安全系数，Vacmax是最大的输入电压有效值。为了留一定的安全裕量，选择最大反向击穿电压为600V的器件。Among them, 1.25 is the internal safety factor, and V acmax is the maximum effective value of the input voltage. In order to leave a certain safety margin, a device with a maximum reverse breakdown voltage of 600V is selected.
EMI电路，用于减少外部环境岁整流滤波后的24V正向脉动的直流电的电磁干扰。The EMI circuit is used to reduce the electromagnetic interference of the 24V positive pulsating DC power after rectification and filtering in the external environment.
在本实施例中，EMI电路有两个功能，其中一个功能是将摆幅较大的仅包含正半周的电压波形信号转变为一个比较开滑的直流信号；另一个功能就是吸收高dv/at和高di/at，为了改善反激式开关电源系统的电磁干扰性能。In this embodiment, the EMI circuit has two functions. One of the functions is to convert a voltage waveform signal with a large swing that only contains the positive half cycle into a relatively open-slide DC signal; the other function is to absorb high dv/at and high di/at in order to improve the electromagnetic interference performance of the flyback switching power supply system.
在本实施例中，EMI电路包括电容C1、电感L1和电容C2，电容C1、电感L1和电容C2构成滤波，可以达到一级滤波的效果。电容C1和电容C2是差模电容器，L1是共模电感，在工程中共模电感两边的线圈很难做到完全对称，因此从某种程度上讲它也是差模电感，也可以抑制差模噪声。In this embodiment, the EMI circuit includes capacitor C1, inductor L1 and capacitor C2, which form a filter to achieve the effect of primary filtering. Capacitors C1 and C2 are differential mode capacitors, and L1 is a common mode inductor. In engineering, it is difficult to achieve complete symmetry between the coils on both sides of the common mode inductor, so to some extent it is also a differential mode inductor, which can also suppress differential mode noise.
RCD钳位电路，用于限制RCD在动作时的电压尖峰，防止由于电流突然切断而在电路中产生过压。The RCD clamping circuit is used to limit the voltage spike when the RCD is in action, preventing overvoltage from occurring in the circuit due to sudden current cutoff.
在本实施例中，在MOS管断开瞬间，原边漏感和MOS管漏源极的寄生电容Cds会产生谐振，这将使得MOS管漏极引脚上有很高的尖峰电压，容易导致MOS管雪崩击穿甚至爆炸。In this embodiment, when the MOS tube is disconnected, the primary leakage inductance and the parasitic capacitance Cds of the drain-source of the MOS tube will resonate, which will cause a high peak voltage on the drain pin of the MOS tube, which may easily lead to avalanche breakdown or even explosion of the MOS tube.
在本实施例中，本电路对于RCD钳位电路元件的选择如下：In this embodiment, the selection of RCD clamp circuit components for this circuit is as follows:
限流电阻R3当MOS管刚关断时，电容C6上还没有电压它的电阻近似于零，这时MOS管漏极的高压经过二极管D1、电容C6和变压器原边绕组形成回路。如果不加R3，这条回路中的电流将会非常大，极有可能会导致D1和C6的损坏。为了解决这一问题，在这条回路中加一个限流电阻R3，以确保D1和C6器件的安全。这里电阻R3取200Ω，回路中最大电流大约0.9A，不会超过D1和C6允许通过的最大电流。When the MOS tube is just turned off, there is no voltage on the capacitor C6 and its resistance is close to zero. At this time, the high voltage of the MOS tube drain passes through the diode D1, capacitor C6 and the primary winding of the transformer to form a loop. If R3 is not added, the current in this loop will be very large, which is very likely to cause damage to D1 and C6. In order to solve this problem, a current limiting resistor R3 is added to this loop to ensure the safety of D1 and C6 devices. Here, the resistor R3 is 200Ω, and the maximum current in the loop is about 0.9A, which will not exceed the maximum current allowed by D1 and C6.
确定钳位电容C6时，首先应该确定RCD网络钳位电压的数值，其公式为When determining the clamping capacitor C6, the value of the RCD network clamping voltage should be determined first, and the formula is:
Velamp＝Vas-Vbus＝552V-373V＝179VVelamp＝Vas-Vbus＝552V-373V＝179V
则钳位电容C6的容值为：Then the capacitance of clamping capacitor C6 is:
钳位电阻R1当MOS管导通时，钳位电容C6需要把吸收的能量释放给钳位电阻R1，由于R1消耗的功率P＝V2/R1，故可以得出R1的计算公式为：When the MOS tube is turned on, the clamping capacitor C6 needs to release the absorbed energy to the clamping resistor R1. Since the power consumed by R1 is P = V2/R1, the calculation formula of R1 can be obtained as follows:
钳位二极管D1的最大平均正向输出电流至少为MOS管峰值电流的一半，用公式表示：The maximum average forward output current of the clamping diode D1 is at least half of the peak current of the MOS tube, which can be expressed by the formula:
I0≥0.5×Ippk＝0.5×0.52A＝0.26AI 0 ≥ 0.5 × I ppk = 0.5 × 0.52 A = 0.26 A
为了留一定的安全裕量，这里选择最大正向输出平均电流为1A的器件。本系统所选电源管理芯片的MOS管耐压值为650V，在实际使用时需要15％的降额。因此，M0S管的最大漏源极电压为：In order to leave a certain safety margin, a device with a maximum forward output average current of 1A is selected here. The MOS tube withstand voltage of the power management chip selected in this system is 650V, and a 15% derating is required in actual use. Therefore, the maximum drain-source voltage of the MOS tube is:
Vdsmax＝650×(1-0.15)V＝552VV dsmax = 650 × (1-0.15) V = 552 V
D1的最大直流阻断电压应满足：The maximum DC blocking voltage of D1 should meet the following requirements:
Vdc≥1.4×Vdsmax＝1.4×552V＝772.8VV dc ≥1.4×V dsmax ＝1.4×552V＝772.8V
其中，1.4为安全系数，这里选择最大直流阻断电压为1000V的器件。综合考虑二极管的技术指标，最终选择M7型二极管。Among them, 1.4 is the safety factor, and here we choose a device with a maximum DC blocking voltage of 1000 V. Taking into account the technical indicators of the diode, the M7 diode is finally selected.
变压器模块，用于将24V正向脉动的直流电转化为交流的PWM信号。The transformer module is used to convert 24V positive pulsating DC power into AC PWM signal.
输出整流电路，用于将交流的PWM信号转换为稳定的12V直流信号。The output rectifier circuit is used to convert the AC PWM signal into a stable 12V DC signal.
控制电路，用于监测变压器模块的电压调整过程，并根据监测生成用于调节电路系统的操作信号；A control circuit, used for monitoring the voltage regulation process of the transformer module and generating an operation signal for regulating the circuit system according to the monitoring;
其中，整流滤波电路的输出端与EMI电路的输入端电性连接；EMI电路的输出端与RCD钳位电路的输入端电性连接；RCD钳位电路的输出端与变压器的输入端电性连接；变压器模块的输出端与输出整流电路的输入端电性连接；RCD钳位电路的输出端与控制电路的输入端电性连接；控制电路的输入端与变压器模块的输入端电性连接。Among them, the output end of the rectifier and filter circuit is electrically connected to the input end of the EMI circuit; the output end of the EMI circuit is electrically connected to the input end of the RCD clamping circuit; the output end of the RCD clamping circuit is electrically connected to the input end of the transformer; the output end of the transformer module is electrically connected to the input end of the output rectifier circuit; the output end of the RCD clamping circuit is electrically connected to the input end of the control circuit; the input end of the control circuit is electrically connected to the input end of the transformer module.
在本实施例中，还包括：突入浪涌抑制电路，用于提供过电压保护，防止由于电压浪涌而导致的设备损坏。In this embodiment, it also includes: an inrush surge suppression circuit for providing overvoltage protection to prevent equipment damage caused by voltage surges.
具体的，如图4所示，RCD钳位电路具体包括电阻R1、电容C6、电阻R3、二极管D5，电阻R1与电容C6并联后与电阻R3的一端串联，电阻R3的另一端与二极管D5的负极电性连接。Specifically, as shown in FIG. 4 , the RCD clamp circuit specifically includes a resistor R1 , a capacitor C6 , a resistor R3 , and a diode D5 . The resistor R1 is connected in parallel with the capacitor C6 and then connected in series with one end of the resistor R3 . The other end of the resistor R3 is electrically connected to the negative electrode of the diode D5 .
具体的，如图4所示，变压器模块的初级线圈与RCD钳位电路相连，以接收24V正向脉动的直流电，变压器模块的一组次级线圈连接控制电路并接地，变压器模块的另一组次级线圈连接输出整流电路。Specifically, as shown in FIG4 , the primary coil of the transformer module is connected to the RCD clamping circuit to receive 24V positive pulsating DC power, a set of secondary coils of the transformer module is connected to the control circuit and grounded, and another set of secondary coils of the transformer module is connected to the output rectifier circuit.
具体的，如图4所示，控制电路包括电源管理模块NCP1239、电解电容C5、电阻R4、电阻R5、电阻R6、电阻R7、电阻R8、电阻R9、二极管D7，电阻R6与电阻R7并联后的一端与电源管理模块NCP1239的FB引脚电性连接；电阻R8、电阻R9并联后的一端与电源管理模块NCP1239的CS引脚电性连接；电源管理模块NCP1239的CS引脚与电源管理模块NCP1239的GND引脚共地；电源管理模块NCP1239的FB引脚与电阻R5的一端电性连接，电阻R5的另一端与二极管D7的正极电性连接；电源管理模块NCP1239的VCC引脚与电阻R4的一端电性连接，电阻R4的另一端与二极管D7的负极电性连接；电阻R4的一端与电解电容C5的正极电性连接；电源管理模块NCP1239的DRV引脚与二极管D5的正极电性连接。Specifically, as shown in FIG4 , the control circuit includes a power management module NCP1239, an electrolytic capacitor C5, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, and a diode D7. One end of the resistor R6 and the resistor R7 connected in parallel is electrically connected to the FB pin of the power management module NCP1239; one end of the resistor R8 and the resistor R9 connected in parallel is electrically connected to the CS pin of the power management module NCP1239; the CS pin of the power management module NCP1239 is electrically connected to the power management module NCP1239. The GND pin of CP1239 is grounded; the FB pin of the power management module NCP1239 is electrically connected to one end of the resistor R5, and the other end of the resistor R5 is electrically connected to the positive electrode of the diode D7; the VCC pin of the power management module NCP1239 is electrically connected to one end of the resistor R4, and the other end of the resistor R4 is electrically connected to the negative electrode of the diode D7; one end of the resistor R4 is electrically connected to the positive electrode of the electrolytic capacitor C5; the DRV pin of the power management module NCP1239 is electrically connected to the positive electrode of the diode D5.
具体的，如图4所示，突入浪涌抑制电路包括保险丝和压敏电阻，压敏电阻与整流滤波电路并联后串接保险丝。Specifically, as shown in FIG. 4 , the inrush surge suppression circuit includes a fuse and a varistor. The varistor is connected in parallel with the rectifier and filter circuit and then in series with the fuse.
在本实施例中，通过在火线和零线上加保险丝和压敏电阻来抑制浪涌。当电路中存在浪涌电流时，保险丝会动作，通过断开电流来保护电源。当电路中存在浪涌电压时，压敏电阻会起作用，吸收浪涌电压来保护后级电路。In this embodiment, the surge is suppressed by adding a fuse and a varistor to the live wire and the neutral wire. When there is a surge current in the circuit, the fuse will act to protect the power supply by disconnecting the current. When there is a surge voltage in the circuit, the varistor will act to absorb the surge voltage to protect the subsequent circuit.
保险丝的技术指标主要有：额定电压、额定电流和熔断速度。本系统输入电压的范围：85～264V，所以选择额定电压为250V的器件。保险丝额定电流的计算公式为：The main technical indicators of fuses are: rated voltage, rated current and fusing speed. The input voltage range of this system is: 85~264V, so a device with a rated voltage of 250V is selected. The calculation formula for the rated current of the fuse is:
其中，2是安全系数，0.5是功率因数值，η是效率，Vacmin是最小的输入电压有效值。综合考虑保险丝的技术指标，最终选择型号为T2A/250V的保险丝。其中T表示该款保险丝为慢断型，额定电流2A，额定电压250V。Among them, 2 is the safety factor, 0.5 is the power factor value, η is the efficiency, and V acmin is the minimum effective value of the input voltage. Taking the technical indicators of the fuse into consideration, the fuse model T2A/250V is finally selected. T means that the fuse is a slow-blow type with a rated current of 2A and a rated voltage of 250V.
压敏电阻(压敏器)在选用压敏器时，主要考虑压敏电压这一指标。压敏电压的计算公式为：When selecting a varistor (varistor), the varistor voltage is the main indicator to consider. The calculation formula of the varistor voltage is:
其中，a取1.2，b取0.85，c取0.9。a，b，c分别代表电压纹波系数，压敏电阻误差，老化系数；综合考虑压敏器的技术指标，最终选择10D471型压敏器。D指压敏器外形是圆形，10指压敏器直径是10mm。Among them, a is 1.2, b is 0.85, and c is 0.9. a, b, and c represent voltage ripple coefficient, varistor error, and aging coefficient respectively. After comprehensive consideration of the technical indicators of the varistor, the 10D471 varistor is finally selected. D refers to the circular shape of the varistor, and 10 refers to the diameter of the varistor is 10mm.
本反激式电源采用DCM工作模式，运用PWM调制技术(保持工作频率不变，通过调整脉冲导通时间来改变占空比，从而实现输出端电压的稳定)，反馈方式为PSR，通过辅助绕组间接采样输出电压，通过辅助绕组与次级线圈的匝比关系计算输出电压。PSR技术只使用一个辅助绕组，不需要在次级侧添加任何反馈装置，节省了使用光耦合器和TL431的成本，同时也减少了外围电路的面积，环路控制模式为电流型。电源中的核心电路设计包含了突入浪涌抑制电路，整流滤波电路、EMI电路、RCD钳位电路、输出整流电路、控制电路、变压器模块。考虑到拓扑结构、关键性能指标、性价比、芯片的典型应用功率等因素，电源管理芯片选择NCP1239。This flyback power supply adopts DCM working mode and uses PWM modulation technology (keeping the working frequency unchanged, changing the duty cycle by adjusting the pulse conduction time, so as to achieve the stability of the output voltage). The feedback mode is PSR, and the output voltage is indirectly sampled through the auxiliary winding, and the output voltage is calculated by the turn ratio relationship between the auxiliary winding and the secondary coil. PSR technology only uses one auxiliary winding and does not require any feedback device to be added on the secondary side, saving the cost of using optocouplers and TL431, while also reducing the area of the peripheral circuit. The loop control mode is current type. The core circuit design in the power supply includes inrush surge suppression circuit, rectifier filter circuit, EMI circuit, RCD clamp circuit, output rectifier circuit, control circuit, and transformer module. Considering factors such as topology, key performance indicators, cost performance, and typical application power of the chip, the power management chip NCP1239 is selected.
以上所述，仅为本发明较佳的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，根据本发明的技术方案及其发明构思加以等同替换或改变，都应涵盖在本发明的保护范围之内。The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.
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