[go: up one dir, main page]

WO2019056830A1 - 一种电流采样电路 - Google Patents

一种电流采样电路 Download PDF

Info

Publication number
WO2019056830A1
WO2019056830A1 PCT/CN2018/094818 CN2018094818W WO2019056830A1 WO 2019056830 A1 WO2019056830 A1 WO 2019056830A1 CN 2018094818 W CN2018094818 W CN 2018094818W WO 2019056830 A1 WO2019056830 A1 WO 2019056830A1
Authority
WO
WIPO (PCT)
Prior art keywords
resistor
circuit
terminal
current sampling
voltage
Prior art date
Application number
PCT/CN2018/094818
Other languages
English (en)
French (fr)
Inventor
李湘
卢泽伟
阮启钦
刘海霞
Original Assignee
广州金升阳科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 广州金升阳科技有限公司 filed Critical 广州金升阳科技有限公司
Publication of WO2019056830A1 publication Critical patent/WO2019056830A1/zh

Links

Images

Classifications

    • 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
    • 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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter

Definitions

  • the invention relates to a primary current sampling circuit of an isolated converter, in particular to a primary current sampling circuit of a flyback converter.
  • the circuit structure of the scheme is simple and effective, and the sampling of the primary current can be ensured quickly and without distortion, and the cost is low and the volume is small, so it is widely used in low power products.
  • the current sampling circuit described above has a problem that the current sampling resistor R1 consumes a large amount of power.
  • the power of the product is large, more resistors are needed for parallel use.
  • the application of the current sampling circuit in a power isolation transformer or a high power density low power product is limited by problems such as low product efficiency, increased temperature, increased cost, and increased layout space.
  • the invention solves the problem that the sampling resistor of the primary current sampling circuit of the isolated converter has large power consumption, and provides a method for sampling the primary current of the isolated converter, so that the power consumption of the sampling resistor is small, thereby reducing the number of sampling resistors, Improving product efficiency and product power density can broaden the application field of the current sampling method, and the circuit structure is simple, easy to implement and practical.
  • a current sampling circuit comprising a sampling resistor R1, a low-pass filter circuit and a control IC, wherein the sampling resistor R1 samples a primary current of an external circuit and converts it into a voltage sampling signal;
  • the input end of the filter circuit is connected to the voltage sampling signal for filtering the high frequency voltage spike existing in the voltage sampling signal, and then outputting the filtered voltage sampling signal to the current sampling pin of the control IC;
  • a DC bias circuit is further included, the first terminal of the DC bias circuit is connected to the current sampling pin of the control IC, and the second terminal of the DC bias circuit is connected to the positive input of the power supply or the power supply pin VCC of the control IC for reducing the sampling The power consumption of resistor R1.
  • the DC bias circuit includes a resistor R4, a first terminal of the resistor R4 is connected to a current sampling pin of the control IC, and a second terminal of the resistor R4 is connected to the control IC. Power supply pin VCC.
  • the DC bias circuit further includes a linear regulator circuit, wherein an input end of the linear regulator circuit is connected to the input voltage positive terminal to provide a stable DC bias voltage for the current sampling pin of the control IC;
  • the second terminal of R4 is connected to the output terminal of the linear regulator circuit by the power supply pin VCC connected to the control IC.
  • the linear regulator circuit comprises an NPN transistor Q2, a Zener diode D2 and a resistor R5.
  • the first terminal of the resistor R5 is connected to the power input positive pole, and the second terminal of the resistor R5 is connected to the Zener diode.
  • a cathode of D2 and a base of the NPN transistor Q2 an anode of the Zener diode D2 is connected to a power supply input negative pole
  • a collector of the NPN transistor Q2 is connected to a power supply input positive pole
  • an emitter of the NPN transistor Q2 is connected to a resistor R4 The second terminal.
  • the DC bias circuit includes a constant current source IC2, the constant current source IC2 is anode connected to the power input positive pole, and the constant current source IC2 is cathode connected to the current sampling pin of the control IC. .
  • a current sampling circuit further includes a voltage feedforward circuit connected between the positive pole of the power input and the current sampling pin of the control IC.
  • the voltage feedforward circuit includes a resistor R3, one end of the resistor R3 is connected to the power input positive pole, and the other end of the resistor R3 is connected to the current sampling pin of the control IC.
  • the low-pass filter circuit includes a resistor R2 and a capacitor C2, and the first terminal of the resistor R2 is connected to the first terminal of the capacitor C2 and the current sampling pin of the control IC, and the resistor R2 The second terminal is connected to the voltage sampling signal of the sampling resistor in the external circuit, and the second terminal of the second capacitor C2 is connected to the power input negative pole.
  • control IC current sampling pin CS is a current sampling signal input end for detecting the primary current signal; the primary current of the flyback converter is superimposed on the parasitic capacitance of the transformer in addition to the primary excitation current.
  • the generated high-frequency peak current, the voltage signal sampled by the first resistor R1 has a high-frequency spike voltage, and the low-pass filter circuit filters the high-frequency voltage spike to avoid false triggering of the control IC;
  • the primary peak current Ip of the flyback converter When the output current increases, the primary peak current Ip of the flyback converter will increase accordingly.
  • the voltage of the control IC current sampling pin reaches the set value of the control IC, the IC will enter the overcurrent protection. Mode; since the primary side peak current Ip of the flyback converter is inversely proportional to the input voltage, if there is no voltage feedforward circuit, for the flyback converter with a wide input voltage range, the product has a low current limit and a small input high limit.
  • the feedforward circuit can add a DC signal inversely proportional to the input voltage on the AC voltage signal, so that the peak voltage of the current sampling pin of the control IC is relatively close to the input voltage, thereby making the product overcurrent point throughout
  • the input voltage range is equivalent, which helps to improve the reliability of the product. For applications with a fixed input voltage or a small input voltage range, since there is no need to compensate for the primary current change caused by the input voltage change, the voltage can be eliminated. Feed circuit.
  • the control IC current sampling pin voltage waveform with DC bias voltage is shown in Figure 3.
  • the increased DC bias circuit can make the DC component VDC of the VCS voltage relatively stable, even if a large bias voltage is added, the product can be made.
  • the output overcurrent point remains relatively balanced. Since the VCS peak voltage is not much different from the conventional scheme, the VCS AC part VAC can be significantly reduced.
  • the VCS AC part VAC is approximately equal to the voltage across the first resistor, so the resistance of the first resistor can be Significantly reduced, thereby reducing the power consumption of the first resistor, reducing the number of sampling resistors, and achieving the beneficial effects of improving product efficiency and increasing product power density.
  • Figure 1 is a schematic diagram of a conventional current sampling
  • FIG. 2 is a circuit block diagram of a first embodiment of the present invention
  • FIG. 3 is a waveform diagram of a control IC current sampling pin when the DC bias is added according to the present invention
  • FIG. 4 is a circuit schematic diagram of a circuit applied to a flyback topology according to a first embodiment of the present invention
  • FIG. 5 is a circuit schematic diagram of a circuit applied to a flyback topology according to a second embodiment of the present invention.
  • FIG. 6 is a circuit schematic diagram of a circuit applied to a flyback topology according to a fourth embodiment of the present invention.
  • Fig. 4 shows a schematic diagram of a first embodiment, the power level topology of which is a flyback topology.
  • the flyback topology circuit includes a transformer T1, an N-MOS transistor Q1, a first diode D1, and a first capacitor C1.
  • the transformer includes a first primary winding, a first secondary winding, and a flyback circuit.
  • the connection relationship is: the first primary winding different end is connected to the power input positive pole, and the first primary winding is terminated by the same name as the drain of the N-MOS transistor Q1, the N-MOS
  • the source output current of the tube Q1 is given to the current sampling circuit of the present invention; the same end of the first secondary winding is connected to the anode of the first diode D1, and the cathode of the first diode D1 is connected to the output.
  • the positive terminal of the first secondary winding is connected to the negative terminal of the output terminal, the first terminal of the first capacitor C1 is connected to the positive terminal of the output terminal, and the second terminal of the first capacitor C1 is Connect the output terminal to the negative terminal.
  • a current sampling circuit of the present invention includes a sampling resistor R1, a low-pass filter circuit and a control IC, and a DC bias circuit.
  • the sampling resistor R1 samples the primary current signal of the flyback topology circuit and converts it into a voltage sampling signal; the input end of the low-pass filter circuit is connected to the voltage sampling signal for filtering the high frequency existing in the voltage sampling signal a voltage spike, and then outputting the filtered voltage sampling signal to the current sampling pin of the control IC; the first terminal of the DC bias circuit is connected to the current sampling pin CS of the control IC, and the second terminal of the DC bias circuit is connected to the power supply of the control IC The pin VCC is used to reduce the power consumption of the sampling resistor R1.
  • the low-pass filter circuit includes a second resistor R2 and a second capacitor C2, the first terminal of the second resistor R2 is connected to the first terminal of the second capacitor C2, and the second terminal of the second resistor R2 Connecting the source of the N-MOS transistor, the second terminal of the second capacitor C2 is connected to the power input negative pole, and the first terminal of the second capacitor is connected to the current sampling pin of the control IC;
  • the DC bias circuit includes a fourth resistor R4, the first terminal of the fourth resistor R4 is connected to the current sampling pin CS of the control IC, and the second terminal of the fourth resistor R4 is connected to the control IC.
  • the power supply pin VCC The power supply pin VCC.
  • the power supply pin voltage of the control IC is a relatively stable DC voltage VCC, usually about 10V, and the VCC is divided by the fourth resistor R4, the second resistor R2, and the first resistor R1.
  • the DC bias voltage VDC generated on the current sampling pin CS of the control IC is VCC*(R1+R2)/(R1+R2+R4). Since R1 is much smaller than R2 and R4, the VDC size is approximately VCC*R2/ (R2+R4), the protection voltage set by the IC corresponding to the current sampling pin CS of the control IC is usually 0.5V to 1V. For example, TI's UC2843 control IC sets the IC overcurrent point to the normal comparison.
  • the resistance of the first resistance is reduced by half, the loss of the first resistor may be reduced by half; since the The resistance of the fourth resistor and the second resistor are relatively large, and the power consumption of the fourth resistor and the second resistor can be controlled within 10 mW, and the loss is substantially negligible; In practical applications, the first resistor power consumption can be reduced by 0.165W.
  • the first resistor described in the conventional scheme needs to be used in parallel with 3 to 4 1206 1/2W resistors. According to the invention, only two 1206 1/2W resistors need to be used in parallel to meet the resistance power derating requirement.
  • FIG. 5 is a schematic diagram of a second embodiment, the power stage topology of which is a flyback topology, which is different from the first embodiment in that a DC bias circuit passes through the constant current source IC 2 at the second resistor and the The voltage generated on a resistor is realized, the anode of the constant current source IC2 is connected to the power input positive pole, and the cathode of the constant current source IC2 is connected to the first terminal of the second capacitor C2, that is, the constant current source IC2 The cathode is connected to the current sampling pin of the control IC.
  • the working principle is as follows: the constant current source output current flows through R2 and R1. Since the output current of the constant current source is relatively stable, the voltage drop generated on R2 and R1 is relatively stable, and thus can be obtained and implemented in the first case. Similar benefits. Other circuit connection relationships and principles are the same as those of the first embodiment, and are not described herein again.
  • a voltage feedforward circuit is added, which is connected between the positive pole of the power supply input and the current sampling pin CS of the control IC.
  • the voltage feedforward circuit of the present invention includes a third resistor R3.
  • the first terminal of R3 is connected to the positive input of the power supply, and the second terminal of R3 is connected to the first terminal of R2.
  • the product overcurrent point may be adjusted by the first resistor, the third resistor combined with the fourth resistor and the second resistor, or
  • the first resistor, the third resistor are combined with the constant current source IC2 and the second resistor to adjust, so that the product overcurrent point is relatively stable within the input voltage range, and can be obtained with the first embodiment and the second implementation.
  • similar benefits may be applied to adjust the first resistor, the third resistor combined with the fourth resistor and the second resistor, or The first resistor, the third resistor are combined with the constant current source IC2 and the second resistor to adjust, so that the product overcurrent point is relatively stable within the input voltage range, and can be obtained with the first embodiment and the second implementation.
  • the linear voltage stabilizing circuit comprises a first NPN transistor Q2, a second Zener diode D2 and a fifth resistor R5.
  • the connection mode is: the first terminal of R5 is connected to the positive input of the power source, and the second terminal of R5 is connected to the cathode of D2 and the cathode of Q2.
  • the base, the anode of D2 is connected to the power supply input negative pole, the collector of Q2 is connected to the positive input of the power supply, and the emitter of Q2 is connected to the second terminal of the fourth resistor R4.
  • the mode of the DC bias circuit is not limited thereto, and any circuit capable of providing a stable DC bias voltage is suitable for use in the present invention.
  • the DC bias circuit can also be used in combination with a voltage feedforward circuit.
  • the above is an implementation manner of the current sampling circuit of the present invention applied in a flyback topology circuit.
  • the present invention can also be applied to a forward topology circuit, and the connection relationship and principle of the circuit are the same.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

本发明公开了一种电流采样电路，可应用于反激变换器、正激变换器等拓扑的原边电流采样，通过在控制IC的电流采样引脚预偏置直流电压，可大大减小原边电流采样电阻的采样电压。这种电流采样方法可显著减小采样电阻的阻值与功耗，提升产品效率及产品功率密度，同时拓宽了直接通过功率电阻进行采样原边电流的应用领域，且电路容易实现与实用化。

Description

一种电流采样电路 技术领域
本发明涉及一种隔离变换器的原边电流采样电路，特别涉及反激变换器的原边电流采样电路。
背景技术
在功率较小的隔离变换器上，如输出功率小于10W的DC/DC变换器，由于成本、体积等方面的限制，不宜采用互感器等电路较复杂或占用空间较大的原边电流采样方案。传统的解决方案如图1所示，通过在反激变换器的主功率N-MOS管下串联功率电阻到输入地，直接通过功率电阻对原边电流进行采样，并经过低通滤波后输入至控制IC的原边电流采样引脚，同时为了保证宽输入电压产品过流点的一致性，在原边电流采样引脚增加与输入电压成反比的电压前馈。
该方案电路结构简单有效，既可保证原边电流的采样快速且不失真，且成本低、体积小，故在小功率产品上得到了广泛应用。
然而，当隔离变换器的原边电流增大时，上述的这种电流采样电路存在电流采样电阻R1功耗较大的问题，当产品功率较大时，需采用更多的电阻进行并联使用，使得产品效率较低、温升高、成本增加、占用的布板空间增大等问题，该电流采样电路在功率较大的隔离变换器或高功率密度的小功率产品中的应用受到了限制。
发明内容
本发明要解决上述的隔离变换器原边电流采样电路的采样电阻功耗较大的问题，提供一种隔离变换器原边电流采样方法，使得采样电阻功耗较小，从而减少采样电阻数量、提升产品效率与产品功率密度，可拓宽该电流采样方式的应用领域，且该方法电路结构简单，容易实现与实用化。
本发明的目的是这样实现的，一种电流采样电路，包括采样电阻R1、低通滤波电路和控制IC，所述的采样电阻R1采样外部电路的原边电流，转换为电压采样信号；低通滤波电路的输入端连接到所述的电压采样信号，用于滤除电压采样信号中存在的高频电压尖峰，然后输出经过滤波后的电压采样信号给控制IC的电流采样脚；其特征在于：还包括直流偏置电路，直流偏置电路的第一端子连接控制IC的电流采样脚，直流偏置电路的第二端子连接到电源输入正极或控制IC的供电脚VCC，用于降低所述采样电阻R1的功耗。
优选的，所述的直流偏置电路包括电阻R4，所述的电阻R4的第一端子连接所述的控制IC的电流采样脚，所述的电阻R4的第二端子连接所述的控制IC的供电脚VCC。
进一步的，所述的直流偏置电路还包括线性稳压电路，线性稳压电路的输入端连接输入电压正极，为所述控制IC的电流采样脚提供一个稳定的直流偏置电压；所述电阻R4的第二端子由连接所述的控制IC的供电脚VCC改为连接所述的线性稳压电路输出端。
优选的，所述的线性稳压电路包括NPN三极管Q2、稳压管D2和电阻R5，所述电阻R5的第一端子连接电源输入正极，所述电阻R5的第二端子连接所述稳压管D2的阴极和所述NPN三极管Q2的基极，所述稳压管D2的阳极连接电源输入负极，所述NPN三极管Q2的集电极连接电源输入正极，所述NPN三极管Q2的发射极连接电阻R4的第二端子。
优选的，所述的直流偏置电路包括恒流源IC2，所述的恒流源IC2阳极接所述的电源输入正极，所述的恒流源IC2阴极接所述的控制IC的电流采样脚。
优选的，一种电流采样电路还包括电压前馈电路，连接在电源输入正极与控制IC的电流采样脚之间。
优选的，所述的电压前馈电路包括电阻R3，所述电阻R3的一端连接电源输入正极，所述电阻R3的另一端连接所述控制IC的电流采样脚。
优选的，低通滤波电路包括电阻R2和电容C2，所述的电阻R2的第一端子连接所述的电容C2的第一端子和所述的控制IC的电流采样脚，所述的电阻R2的第二端子连接外部电路中采样电阻的电压采样信号，所述的第二电容C2的第二端子连接电源输入负极。
工作原理为：所述的控制IC电流采样脚CS为电流采样信号输入端，用于检测原边电流信号；反激变换器的原边电流除了原边激磁电流外，还叠加了因变压器寄生电容产生的高频尖峰电流，第一电阻R1采样的电压信号存在高频尖峰电压，低通滤波电路对该高频电压尖峰进行滤波，以避免控制IC误触发；
当输出电流增大时，反激变换器的原边峰值电流Ip会相应增大，当达到所述的控制IC电流采样脚电压达到所述的控制IC设定值后，IC会进入过流保护模式；由于反激变换器的原边峰值电流Ip大小与输入电压成反比，若无电压前馈电路，对于宽输入电压范围的反激变换器，产品过流点输入低限小输入高限大，增加前馈电路可在交流电压信号上叠加一个与输入电压成反比的直流信号，使得在所述的控制IC的电 流采样脚的峰值电压与输入电压相对接近，从而使得产品过流点在整个输入电压范围段相当，有助于提高产品的可靠性，对于输入电压固定或输入电压范围较小的应用，由于无需对输入电压变化引起的原边电流变化进行补偿，可无需所述的电压前馈电路。
有直流偏置电压时的控制IC电流采样脚电压波形如图3所示，增加的直流偏置电路，可使VCS电压的直流分量VDC相对稳定，即使增加较大的偏置电压仍能使产品的输出过流点保持相对平衡，由于VCS峰值电压与传统方案差异不大，VCS交流部分VAC可显著减小，VCS交流部分VAC近似等于第一电阻两端的电压，故第一电阻的阻值可明显减小，从而可降低第一电阻功耗，减小采样电阻数量，达到提高产品效率、提升产品功率密度的有益效果。
附图说明
图1为传统电流采样原理图；
图2为本发明第一实施例电路框图；
图3为本发明增加直流偏置时控制IC电流采样脚电压波形；
图4为本发明第一实施例电路应用于反激拓扑的电路原理图；
图5为本发明第二实施例电路应用于反激拓扑的电路原理图；
图6为本发明第四实施例电路应用于反激拓扑的电路原理图。
具体实施方式
第一实施例
图4示出了第一实施例的原理图，其功率级拓扑为反激拓扑。反激拓扑电路包括一只变压器T1、一只N-MOS管Q1、第一二极管D1、第一电容C1，所述的变压器包括第一原边绕组、第一副边绕组；反激电路的连接关系为：所述的第一原边绕组异名端连接电源输入正极，所述的第一原边绕组同名端接所述的N-MOS管Q1的漏极，所述的N-MOS管Q1的源极输出电流给本发明的电流采样电路；所述的第一副边绕组的同名端连接所述第一二极管D1的阳极，所述第一二极管D1的阴极连接输出端正极，所述的第一副边绕组的异名端连接所述的输出端负极，所述的第一电容C1的第一端子接输出端正极，所述的第一电容C1的第二端子接输出端负极。
本发明的一种电流采样电路，包括采样电阻R1、低通滤波电路和控制IC，还包括直流偏置电路。所述的采样电阻R1采样反激拓扑电路的原边电流信号，转换为电 压采样信号；低通滤波电路的输入端连接所述的电压采样信号，用于滤除电压采样信号中存在的高频电压尖峰，然后输出滤波后的电压采样信号给控制IC的电流采样脚；直流偏置电路的第一端子连接控制IC的电流采样脚CS，直流偏置电路的第二端子连接到控制IC的供电脚VCC，用于降低所述采样电阻R1的功耗。
低通滤波电路包括第二电阻R2和第二电容C2，所述的第二电阻R2的第一端子连接所述的第二电容C2的第一端子，所述的第二电阻R2的第二端子连接所述的N-MOS管的源极，所述的第二电容C2的第二端子连接电源输入负极，同时所述的第二电容的第一端子连接所述的控制IC的电流采样脚；直流偏置电路包括第四电阻R4，所述的第四电阻R4的第一端子连接所述的控制IC的电流采样脚CS，所述的第四电阻R4的第二端子连接所述的控制IC的供电脚VCC。
工作原理为：所述的控制IC的供电脚电压为相对稳定的直流电压VCC，通常为10V左右，VCC通过第四电阻R4、第二电阻R2、第一电阻R1进行分压，在所述的控制IC的电流采样脚CS上产生的直流偏置电压VDC大小为VCC*(R1+R2)/(R1+R2+R4)，由于R1远小于R2和R4，故VDC大小近似为VCC*R2/(R2+R4)，所述的控制IC的电流采样脚CS对应的IC设定的保护电压通常为0.5V～1V，如TI的UC2843控制IC，为使IC的过流点设定为通常比较合适的1.5倍Io左右，一般反激变换器正常工作时的最大的电流采样信号的电压VCS应大于0.6V，若增加的直流偏置电压0.4V，则第一电阻R1两端的峰值电压可降低至0.3V左右(因第一电阻的阻值减小，VCS峰值电压需适当增大，以确保产品过流点相当)，由于原边电流大小不变，由欧姆定律R＝V/I可知，第一电阻R1两端的电压减小一半的情况下，所述的第一电阻的阻值可相应减小一半，又由P＝I 2R可知，流过第一电阻的电流有效值不变的情况下，所述的第一电阻的阻值降低一半，所述的第一电阻的损耗可降低一半；由于所述的第四电阻和所述的第二电阻的阻值较大，所述的第四电阻和所述的第二电阻的功耗可控制在10mW以内，损耗基本可以忽略；在一宽输入6W产品中实际应用，所述的第一电阻功耗可降低0.165W，考虑电阻功率降额，采用传统方案时所述的第一电阻需采用3～4个1206 1/2W电阻并联使用，而采用本发明，仅需2个1206 1/2W电阻并联使用即可满足电阻功率降额要求。
第二实施例
图5示出了第二实施例的原理图，其功率级拓扑为反激拓扑，与第一实施例不同的是：直流偏置电路通过恒流源IC2在所述第二电阻及所述第一电阻上产生的电压实 现，所述的恒流源IC2阳极接所述的电源输入正极，所述的恒流源IC2阴极接所述的第二电容C2的第一端子，即恒流源IC2阴极接控制IC的电流采样脚。
工作原理为：所述的恒流源输出电流流经R2、R1，由于所述的恒流源输出电流相对稳定，在R2、R1上产生的压降也相对稳定，从而可得到与实施案例一类似的有益效果。其它电路连接关系和原理与第一实施例相同，在此不再赘述。
第三实施例
在第一实施例和第二实施例的基础上，增加了电压前馈电路，连接在电源输入正极与控制IC的电流采样脚CS之间。
本发明的电压前馈电路包括第三电阻R3，R3的第一端子连接电源输入正极，R3的第二端子连接R2的第一端子。
在输入电压不固定或输入电压范围较宽的情况下，产品过流点可通过所述的第一电阻、所述的第三电阻结合所述的第四电阻和第二电阻进行调节，或通过所述的第一电阻、所述的第三电阻结合恒流源IC2和第二电阻进行调节，使得产品过流点在输入电压范围内相对稳定，同时可得到与第一实施例和第二实施例类似的有益效果。
第四实施例
图6示出了第四实施例的原理图，在第一实施例的基础上，直流偏置电路的第四电阻R4的第二端子连接方式由所述的控制IC的供电脚VCC改为所述的线性稳压电路输出端，线性稳压电路为控制IC的CS脚提供一个稳定的直流偏置电压。其余连接方式不变。线性稳压电路包括第一NPN三极管Q2、第二稳压管D2和第五电阻R5，其连接方式为：R5的第一端子连接电源输入正极，R5的第二端子连接D2的阴极和Q2的基极，D2的阳极连接电源输入负极，Q2的集电极连接电源输入正极，Q2的发射极连接第四电阻R4的第二端子。
直流偏置电路的方式不限于此，凡是能提供稳定的直流偏置电压的电路，都适用于本发明。直流偏置电路也可以与电压前馈电路组合使用。
以上是本发明的一种电流采样电路应用在反激拓扑电路中的实施方式，本发明同样可以应用于正激拓扑电路中，电路的连接关系和原理均相同。
以上仅是本发明的优选实施方式，应当指出的是，上述优选实施方式不应视为对本发明的限制，对于本技术领域的普通技术人员来说，在本发明电路中加入不同稳压、控制策略，可以得到类似的有益效果，对于本技术领域的普通技术人员来说，在不脱离本发明的精神和范围内，还可以做出若干改进和润饰，这些改进和润饰也应视为本发 明的保护范围，这里不再用实施例赘述，本发明的保护范围应当以权利要求所限定的范围为准。

Claims (8)

  1. 一种电流采样电路，包括采样电阻R1、低通滤波电路和控制IC，所述的采样电阻R1采样外部电路的原边电流，转换为电压采样信号；低通滤波电路的输入端连接所述的电压采样信号，用于滤除电压采样信号中存在的高频电压尖峰，然后输出经过滤波后的电压采样信号给控制IC的电流采样脚；其特征在于：还包括直流偏置电路，直流偏置电路的第一端子连接控制IC的电流采样脚，直流偏置电路的第二端子连接到电源输入正极或控制IC的供电脚VCC，用于降低所述采样电阻R1的功耗。
  2. 根据权利要求1所述的电流采样电路，其特征在于：所述的直流偏置电路包括电阻R4，所述的电阻R4的第一端子连接所述的控制IC的电流采样脚，所述的电阻R4的第二端子连接所述的控制IC的供电脚VCC。
  3. 根据权利要求1所述的电流采样电路，其特征在于：所述的直流偏置电路包括恒流源IC2，所述的恒流源IC2阳极接所述的电源输入正极，所述的恒流源IC2阴极接所述的控制IC的电流采样脚。
  4. 根据权利要求2所述的电流采样电路，其特征在于：所述的直流偏置电路还包括线性稳压电路，线性稳压电路的输入端连接输入电压正极，为所述控制IC的电流采样脚提供一个稳定的直流偏置电压；所述电阻R4的第二端子由连接所述的控制IC的供电脚VCC改为连接所述的线性稳压电路输出端。
  5. 根据权利要求4所述的电流采样电路，其特征在于：所述的线性稳压电路包括NPN三极管Q2、稳压管D2和电阻R5，所述电阻R5的第一端子连接电源输入正极，所述电阻R5的第二端子连接所述稳压管D2的阴极和所述NPN三极管Q2的基极，所述稳压管D2的阳极连接电源输入负极，所述NPN三极管Q2的集电极连接电源输入正极，所述NPN三极管Q2的发射极连接电阻R4的第二端子。
  6. 根据权利要求2至5中任一项所述的电流采样电路，其特征在于：还包括电压前馈电路连接在电源输入正极与控制IC的电流采样脚之间。
  7. 根据权利要求6所述的电流采样电路，其特征在于：所述的电压前馈电路包括电阻R3，所述电阻R3的一端连接电源输入正极，所述电阻R3的另一端连接所述控制IC的电流采样脚。
  8. 根据权利要求1所述的电流采样电路，其特征在于：所述的低通滤波电路包括电阻R2和电容C2，所述的电阻R2的第一端子连接所述的电容C2的第一端子和所述的控制IC的电流采样脚，所述的电阻R2的第二端子连接外部电路中采样电阻的电压采样信号，所述的第二电容C2的第二端子连接电源输入负极。
PCT/CN2018/094818 2017-09-22 2018-07-06 一种电流采样电路 WO2019056830A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN201710862715.1A CN107707124A (zh) 2017-09-22 2017-09-22 一种电流采样电路
CN201710862715.1 2017-09-22

Publications (1)

Publication Number Publication Date
WO2019056830A1 true WO2019056830A1 (zh) 2019-03-28

Family

ID=61171925

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2018/094818 WO2019056830A1 (zh) 2017-09-22 2018-07-06 一种电流采样电路

Country Status (2)

Country Link
CN (1) CN107707124A (zh)
WO (1) WO2019056830A1 (zh)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107707124A (zh) * 2017-09-22 2018-02-16 广州金升阳科技有限公司 一种电流采样电路

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0866021A (ja) * 1994-08-24 1996-03-08 Star Micronics Co Ltd スイッチング電源装置
CN202043032U (zh) * 2011-05-19 2011-11-16 深圳市振华微电子有限公司 一种开关电源微功耗启动电路
JP2013192329A (ja) * 2012-03-13 2013-09-26 Yokogawa Electric Corp スイッチング電源装置
CN107707124A (zh) * 2017-09-22 2018-02-16 广州金升阳科技有限公司 一种电流采样电路

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7999524B2 (en) * 2007-06-04 2011-08-16 Texas Instruments Incorporated Interleaved power factor correction pre-regulator phase management circuitry
CN102255511B (zh) * 2011-06-24 2013-06-12 航天长峰朝阳电源有限公司 电阻网络信号补偿电路
CN203481799U (zh) * 2013-09-02 2014-03-12 广州德励电子科技有限公司 反激偏置保护电路
CN104540292B (zh) * 2014-12-31 2017-09-22 生迪光电科技股份有限公司 适用于可控硅调光器电路上的调光电路和调光系统
CN106155163A (zh) * 2016-09-19 2016-11-23 中国电子科技集团公司第十八研究所 基于静态补偿的空间电源控制器功率正线端电流采样电路

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0866021A (ja) * 1994-08-24 1996-03-08 Star Micronics Co Ltd スイッチング電源装置
CN202043032U (zh) * 2011-05-19 2011-11-16 深圳市振华微电子有限公司 一种开关电源微功耗启动电路
JP2013192329A (ja) * 2012-03-13 2013-09-26 Yokogawa Electric Corp スイッチング電源装置
CN107707124A (zh) * 2017-09-22 2018-02-16 广州金升阳科技有限公司 一种电流采样电路

Also Published As

Publication number Publication date
CN107707124A (zh) 2018-02-16

Similar Documents

Publication Publication Date Title
CN100525040C (zh) 一种开关电源输出电压的采样反馈电路
US20110261594A1 (en) Power supply with input filter-controlled switch clamp circuit
CN113067469B (zh) 一种快速响应环路补偿电路、环路补偿芯片及开关电源
TW201725839A (zh) 電源供應裝置
CN108599572A (zh) 一种光耦隔离加权反馈控制方法
CN116231591A (zh) 一种有源箝位反激式变换器的过功率保护电路
CN208589920U (zh) 一种隔离型宽范围稳压电源电路
CN109149944B (zh) 一种适用于反激变换器的片上集成有源负压钳位电路
CN108900082B (zh) 开关电源变换系统
CN103762842A (zh) 一种自适应补偿斜坡发生器
WO2019056830A1 (zh) 一种电流采样电路
CN112072928B (zh) 一种自激推挽电路及其辅助供电方法
TW200818101A (en) Voltage stabilizing circuit
CN113176803A (zh) 高压开关电源反馈环路和高压开关电源
CN113765380A (zh) 升压电路
CN206272485U (zh) 一种直流电源变换为正负直流电源的电路
CN213690367U (zh) 一种基于比较放大器的直流稳压电路
CN111193424B (zh) 用于直流无源emi滤波器老炼的电路
CN213027830U (zh) 一种2000w高频逆变器
CN107947549A (zh) 一种基于uc3842的开关电源保护电路
US11171567B1 (en) Power supply device for eliminating ringing effect
CN114070019A (zh) 驱动电路、驱动方法及开关电源
TWI406486B (zh) 用於反激式電源變換器的初級側感測和調整的系統和方法
CN208063054U (zh) 一种dc-dc直流稳压多路电源输出电路
CN218767950U (zh) 稳压电路及控制器

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18859894

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18859894

Country of ref document: EP

Kind code of ref document: A1