阅读说明：本技术 一种负载相关性控制电路及方法 (Load correlation control circuit and method ) 是由 王文廷 颜魏伟 李雷 李斌 王俊 彭海军 张根苗 朱文星 朱炬 陈林贵 于 2020-11-20 设计创作，主要内容包括：本发明涉及一种负载相关性控制电路及方法,电路包括电流取样电路、信号放大电路、电流限制电路、电压限制电路、控制电路以及功率电路。通过功率电路,为主路电压提供假负载电流；通过电流取样电路,对主路的假负载电流进行取样,将电流信号转换为相应的电压信号；通过信号放大电路,对电流取样电路产生的电压信号进行放大,产生幅度较大的电压信号；通过电流限制电路,对假负载电流进行限制,以免假负载电流过大；通过电压限制电路,对副路电压进行限制,以免输出电压过高；通过控制电路,实现假负载电流的控制。本发明对于开关电源的交调性能、轻载动态性能等方面都有突破性的提高,提高了开关电源的输出电流范围和总体效率。(The invention relates to a load correlation control circuit and a method. Providing a dummy load current for the main circuit voltage through a power circuit; sampling the dummy load current of the main circuit through a current sampling circuit, and converting a current signal into a corresponding voltage signal; amplifying the voltage signal generated by the current sampling circuit through a signal amplifying circuit to generate a voltage signal with a larger amplitude; the current of the dummy load is limited through a current limiting circuit so as to prevent the current of the dummy load from being too large; the voltage of the secondary circuit is limited through a voltage limiting circuit so as to prevent the output voltage from being too high; the control of the dummy load current is realized through the control circuit. The invention has breakthrough improvement on the aspects of the intermodulation performance, the light load dynamic performance and the like of the switching power supply, and improves the output current range and the overall efficiency of the switching power supply.)

1. A load correlation control circuit comprises a current sampling circuit, a signal amplifying circuit, a current limiting circuit, a voltage limiting circuit, a control circuit and a power circuit, wherein:

the current sampling circuit comprises a first resistor and a third capacitor;

the signal amplification circuit comprises a second resistor, a third resistor, a fourth resistor and a first operational amplifier B;

a current limiting circuit including a first operational amplifier a, a tenth resistor, an eleventh resistor, and a second transistor;

the voltage limiting circuit comprises a second operational amplifier A, a twelfth resistor, a thirteenth resistor, a sixteenth resistor, a seventeenth resistor and a third transistor;

the control circuit comprises a second operational amplifier B, a third capacitor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor;

and the power circuit comprises a fourteenth resistor, a fifteenth resistor and a first MOS tube.

2. The load-dependent control circuit as claimed in claim 1, wherein in the current sampling circuit, a common terminal is formed by one end of the first resistor and one end of the third capacitor, and is connected to one end of the second resistor in the signal amplifying circuit, one end of the fifteenth resistor in the power circuit, and the source of the first MOS transistor, and a common terminal is formed by the other end of the first resistor and the other end of the third capacitor.

3. The load-dependent control circuit according to claim 1, wherein in the signal amplifying circuit, the other end of the second resistor is connected to pin 5 of the first operational amplifier B; one end of a third resistor is connected to one end of a fifth resistor in the control circuit, the 3 rd pin of the first operational amplifier A and the 7 th pin of the first operational amplifier B in the current limiting circuit, and the other end of the third resistor is connected to one end of a fourth resistor and the 6 th pin of the first operational amplifier B; the other end of the fourth resistor is grounded.

4. The load-dependency control circuit of claim 1, wherein in the current limiting circuit, the first operational amplifier a has a pin 2 connected to the current limiting reference Vr _ Ilim, a pin 8 connected to the voltage source Vcc, a pin 4 connected to ground, and a pin 1 connected to one end of a tenth resistor; the other end of the tenth resistor is connected to the base of the second transistor; a collector of the second transistor is connected to one end of the eleventh resistor, and an emitter of the second transistor is grounded; the other end of the eleventh resistor is connected to one end of the ninth resistor, the thirteenth resistor and the fourteenth resistor.

5. The load-dependent control circuit of claim 1, wherein in the voltage limiting circuit, the 2 nd pin of the second operational amplifier a is connected to the secondary minimum voltage reference Va _ unr _ min, the 3 rd pin is connected to one end of the sixteenth resistor and one end of the seventeenth resistor, the 8 th pin is connected to the voltage source Vcc, the 4 th pin is connected to the ground, and the 1 st pin is connected to one end of the twelfth resistor; the other end of the twelfth resistor is connected to the base electrode of the third transistor; the other end of the sixteenth resistor is connected to the front end of the secondary voltage, the other end of the seventeenth resistor is grounded, the collector of the third transistor is connected to one end of the thirteenth resistor, and the emitter of the third transistor is grounded.

6. The load dependency control circuit as claimed in claim 1, wherein in the control circuit, the 6 th pin of the second operational amplifier B is connected to one ends of the fifth resistor and the sixth resistor, the 5 th pin is connected to one ends of the seventh resistor and the eighth resistor, and the 7 th pin is connected to one end of the third capacitor, one end of the eighth resistor and the other end of the ninth resistor; the other end of the seventh resistor is connected to a feedback point Va _ unr _ min of the secondary circuit voltage; the other ends of the sixth resistor and the third capacitor are both grounded.

7. The load-dependent control circuit according to claim 1, wherein in the power circuit, a gate of the first MOS transistor is connected to one end of the fourteenth resistor and the other end of the fifteenth resistor, and a drain of the first MOS transistor is connected to the main-circuit output terminal Vo _ master.

8. A load dependency control method, characterized in that, with a load dependency control circuit according to claim 1, a dummy load current is first supplied to the main circuit voltage via the power circuit; sampling the dummy load current of the main circuit by the current sampling circuit, and converting the current signal into a corresponding voltage signal; amplifying the voltage signal generated by the current sampling circuit through a signal amplifying circuit to generate a voltage signal with a larger amplitude; the current of the dummy load is limited through a current limiting circuit so as to prevent the current of the dummy load from being too large; the voltage of the secondary circuit is limited through a voltage limiting circuit so as to prevent the output voltage from being too high; and finally, the control circuit compares and controls the secondary circuit voltage and the output voltage of the signal amplification circuit to realize the control of the dummy load current.

9. The load correlation control method according to claim 8, wherein the main circuit output current range is as wide as 0-30A, and the voltage deviation of the front end of the secondary circuit is less than or equal to 1% when the main circuit current is 0A, 15A and 30A respectively.

Technical Field

The invention relates to the field of load correlation control, in particular to a load correlation control circuit and method adopting a controllable dummy load current technology.

Background

The conventional load correlation control circuit generally adopts a fixed resistance method to provide dummy load current for main circuit voltage and control the load correlation of the main circuit voltage and the secondary circuit voltage of the switching power supply, and the control circuit has the advantages of convenience in implementation and simple structure. However, the disadvantage is that when the current variation of the main circuit voltage is large, the voltage deviation of the secondary circuit is large, so that the power consumption of the secondary circuit voltage stabilizing circuit is too large or the voltage cannot be stabilized, and even the switch power supply is damaged. When the main circuit dummy load is too large, the problem of excessive power consumption is also brought about. It is apparent that such conventional load-dependent control circuits cannot meet the wide range current output requirements of switching power supplies. Therefore, a new load-dependent control circuit needs to be researched.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides the load correlation control circuit and the method, which are reasonable in design, overcome the defects in the prior art, have good effects and can be widely applied to various switching power supplies such as AC/DC (alternating current/direct current), DC/DC (direct current/direct current) and the like.

In order to achieve the above object 1, the present invention adopts the following technical solutions:

a load correlation control circuit comprises a current sampling circuit, a signal amplifying circuit, a current limiting circuit, a voltage limiting circuit, a control circuit and a power circuit, wherein:

the current sampling circuit comprises a first resistor and a third capacitor;

the signal amplification circuit comprises a second resistor, a third resistor, a fourth resistor and a first operational amplifier B;

a current limiting circuit including a first operational amplifier a, a tenth resistor, an eleventh resistor, and a second transistor;

the voltage limiting circuit comprises a second operational amplifier A, a twelfth resistor, a thirteenth resistor, a sixteenth resistor, a seventeenth resistor and a third transistor;

the control circuit comprises a second operational amplifier B, a third capacitor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor;

and the power circuit comprises a fourteenth resistor, a fifteenth resistor and a first MOS tube.

Preferably, in the current sampling circuit, a common end formed by one end of the first resistor and one end of the third capacitor is connected to one end of the second resistor in the signal amplification circuit, one end of the fifteenth resistor in the power circuit and the source electrode of the first MOS transistor, and a common end formed by the other end of the first resistor and the other end of the third capacitor is grounded;

preferably, in the signal amplifying circuit, the other end of the second resistor is connected to pin 5 of the first operational amplifier B; one end of a third resistor is connected to one end of a fifth resistor in the control circuit, the 3 rd pin of the first operational amplifier A and the 7 th pin of the first operational amplifier B in the current limiting circuit, and the other end of the third resistor is connected to one end of a fourth resistor and the 6 th pin of the first operational amplifier B; the other end of the fourth resistor is grounded;

preferably, in the current limiting circuit, the 2 nd pin of the first operational amplifier a is connected to the current limiting reference Vr _ Ilim, the 8 th pin is connected to the voltage source Vcc, the 4 th pin is grounded, and the 1 st pin is connected to one end of the tenth resistor; the other end of the tenth resistor is connected to the base of the second transistor; a collector of the second transistor is connected to one end of the eleventh resistor, and an emitter of the second transistor is grounded; the other end of the eleventh resistor is connected to one end of the ninth resistor, the thirteenth resistor and the fourteenth resistor;

preferably, in the voltage limiting circuit, a 2 nd pin of the second operational amplifier a is connected to the secondary minimum voltage reference Va _ unr _ min, a 3 rd pin is connected to one end of the sixteenth resistor and one end of the seventeenth resistor, an 8 th pin is connected to the voltage source Vcc, a 4 th pin is connected to the ground, and a 1 st pin is connected to one end of the twelfth resistor; the other end of the twelfth resistor is connected to the base electrode of the third transistor; the other end of the sixteenth resistor is connected to the front end of the secondary voltage, the other end of the seventeenth resistor is grounded, the collector of the third transistor is connected to one end of the thirteenth resistor, and the emitter of the third transistor is grounded;

preferably, in the control circuit, a pin 6 of the second operational amplifier B is connected to one ends of the fifth resistor and the sixth resistor, a pin 5 is connected to one ends of the seventh resistor and the eighth resistor, and a pin 7 is connected to one end of the third capacitor, one end of the eighth resistor and the other end of the ninth resistor; the other end of the seventh resistor is connected to a feedback point Va _ unr _ min of the secondary circuit voltage; the other ends of the sixth resistor and the third capacitor are grounded;

preferably, in the power circuit, the gate of the first MOS transistor is connected to one end of the fourteenth resistor and the other end of the fifteenth resistor, and the drain of the first MOS transistor is connected to the main circuit output terminal Vo _ master.

In order to achieve the above object 2, the present invention adopts the following technical solutions:

providing a dummy load current for a main circuit voltage through a power circuit; sampling the dummy load current of the main circuit by the current sampling circuit, and converting the current signal into a corresponding voltage signal; amplifying the voltage signal generated by the current sampling circuit through a signal amplifying circuit to generate a voltage signal with a larger amplitude; the current of the dummy load is limited through a current limiting circuit so as to prevent the current of the dummy load from being too large; the voltage of the secondary circuit is limited through a voltage limiting circuit so as to prevent the output voltage from being too high; and finally, the control circuit compares and controls the secondary circuit voltage and the output voltage of the signal amplification circuit to realize the control of the dummy load current.

Preferably, the range of the main circuit output current is as wide as 0-30A, and when the main circuit current is 0A, 15A and 30A respectively, the voltage deviation of the front end of the secondary circuit is less than or equal to 1%.

The invention has the following beneficial technical effects:

1. the current limiting technology is adopted to limit the dummy load current of the main circuit voltage so as to prevent the dummy load current from being too large or maladjusted;

2. the voltage limiting technology is adopted to limit the secondary circuit voltage so as to avoid overhigh or maladjustment of the output voltage;

3. by adopting a controllable dummy load current technology, the interactive voltage regulation performance of the main circuit voltage and the secondary circuit voltage of the switching power supply is improved, and the output dynamic performance of the switching power supply under light load is improved;

4. the controllable dummy load current technology is adopted, the controllable minimum voltage difference of the secondary linear voltage stabilizing circuit can be realized, and the overall efficiency of the switching power supply is improved.

Drawings

FIG. 1 is a block diagram of a load dependency control circuit of the present invention;

FIG. 2 is a block diagram of a load dependency control circuit of the present invention;

Detailed Description

The following description of the embodiments of the present invention will be made with reference to the accompanying drawings:

as shown in fig. 1, a structure diagram of a load-dependent control circuit of the present invention mainly includes a current sampling circuit, a signal amplifying circuit, a current limiting circuit, a voltage limiting circuit, a control circuit, a power circuit, and the like.

For the current sampling circuit, the current sampling circuit is constituted by a resistor R1 and a capacitor C3. One end of the resistor R1 and one end of the capacitor C3 form a common end which is connected to one end of a resistor R2 in the signal amplifying circuit, one end of a resistor R15 in the power circuit and a source electrode of the MOS transistor V1, and the other end of the resistor R1 and the other end of the capacitor C3 form a common end which is grounded. By adopting the resistance-capacitance current sampling method, the impact of transient current on the sampling circuit can be effectively prevented.

For the signal amplification circuit, the signal amplification circuit is constituted by a resistor R2, a resistor R3, a resistor R4, and an operational amplifier N1B. The other end of the resistor R2 is connected to pin 5 of the operational amplifier N1B; one end of the resistor R3 is connected to one end of the resistor R5 in the control circuit, the 3 rd pin of the operational amplifier N1A and the 7 th pin of the operational amplifier N1B in the current limiting circuit, and the other end of the resistor R3 is connected to one end of the resistor R4 and the 6 th pin of the operational amplifier N1B; the other end of the second resistor R4 is connected to ground. The resistor R3 and the resistor R4 determine the amplification factor of the signal amplifying circuit. As can be seen from fig. 2, since the input current of the operational amplifier is almost zero, it can be ignored in the circuit of the present invention; therefore, the voltage of the pin 5 and the voltage of the pin 6 of the N1A are equal, the divided voltage of the pin 7 on the pin R4 is the pin 6 voltage, and the amplification factor of the amplifying circuit is (R3+ R4)/R4. The signal amplification function of the circuit can be realized by reasonably designing the resistance values of R3 and R4.

For the current limiting circuit, the current limiting circuit is composed of a resistor R10, a resistor R11, a transistor V2, and an operational amplifier N1A, and plays a role in limiting the dummy current of the main-circuit voltage. The 2 nd pin of the operational amplifier N1A is connected to the current limiting reference Vr _ Ilim, the 8 th pin is connected to the voltage source Vcc, the 4 th pin is grounded, and the 1 st pin is connected to one end of the resistor R10; the other end of the resistor R10 is connected to the base of the transistor V2; the collector of the transistor V2 is connected to one end of the resistor R11, and the emitter of the transistor V2 is grounded; the other end of the resistor R11 is connected to one ends of the resistor R9, the resistor R13, and the resistor R14;

for the voltage limiting circuit, the voltage limiting circuit is composed of a resistor R12, a resistor R13, a resistor R16, a resistor R17, a transistor V3 and an operational amplifier N2A, and plays a role in limiting the sub-circuit voltage. The 2 nd pin of the operational amplifier N2A is connected to the secondary minimum voltage reference Va _ unr _ min, the 3 rd pin is connected to one end of a resistor R16 and one end of a resistor R17, the 8 th pin is connected to the voltage source Vcc, the 4 th pin is grounded, and the 1 st pin is connected to one end of a resistor R12; the other end of the resistor R12 is connected to the base of the transistor V3; the other end of the resistor R16 is connected to the secondary voltage front end, the other end of the resistor R17 is grounded, the collector of the transistor V3 is connected to one end of the resistor R13, and the emitter of the transistor V3 is grounded.

For the control circuit, the control circuit is constituted by resistors R5-R9, a capacitor C3, and an operational amplifier N2B. Wherein, the 6 th pin of the operational amplifier N2B is connected to one ends of the resistor R5 and the resistor R6, the 5 th pin is connected to one ends of the resistor R7 and the resistor R8, and the 7 th pin is connected to one end of the capacitor C3, one end of the resistor R8 and the other end of the resistor R9; the other end of the resistor R7 is connected to the feedback point Va _ unr _ min of the secondary voltage; the other ends of the resistor R6 and the capacitor C3 are both connected to ground. The main circuit power supply dummy load current controllable function is realized by the operation control of the minimum voltage of the front end of the auxiliary circuit voltage and the main circuit voltage dummy load current signal. The resistors R5 and R6 and the resistors R7 and R8 are symmetrically designed, so that the operation of the control circuit is concise, and the design of the control circuit is convenient. Capacitor C3 functions as an integration to filter out ac noise therein.

For the power circuit, the power circuit is composed of a resistor R14, a resistor R15, and a MOS transistor V1. The gate of the MOS transistor V1 is connected to one end of the resistor R14 and the other end of the resistor R15, and the drain of the MOS transistor V1 is connected to the main output Vo _ master. The MOS transistor V1 adopts a power MOS transistor to provide a dummy load current required by the main circuit voltage.

A load correlation control method adopts the load correlation control circuit as shown in the figure 2, firstly, a power circuit is used for providing a dummy load current for a main circuit voltage; sampling the dummy load current of the main circuit by the current sampling circuit, and converting the current signal into a corresponding voltage signal; amplifying the voltage signal generated by the current sampling circuit through a signal amplifying circuit to generate a voltage signal with a larger amplitude; the current of the dummy load is limited through a current limiting circuit so as to prevent the current of the dummy load from being too large; the voltage of the secondary circuit is limited through a voltage limiting circuit so as to prevent the output voltage from being too high; and finally, the control circuit compares and controls the secondary circuit voltage and the output voltage of the signal amplification circuit to realize the control of the dummy load current.

According to the load correlation control circuit designed based on the invention, the range of the main circuit output current is as wide as 0-30A. When the main circuit current is respectively 0A, 15A and 30A, the voltage deviation of the front end of the secondary circuit is less than or equal to 1 percent, and the voltage stabilization problem of the secondary circuit under the condition of no load of the main circuit of the multi-path switch power supply is effectively solved. The minimum voltage difference of the secondary linear voltage stabilizing circuit is controllable, so that the overall efficiency of the switching power supply is greatly improved.

In conclusion, the invention has breakthrough improvement on the aspects of the intermodulation performance, the light-load dynamic performance and the like of the switching power supply, and improves the output current range and the overall efficiency of the switching power supply.

It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.