CN116867141A

CN116867141A - High-precision constant-current power supply circuit

Info

Publication number: CN116867141A
Application number: CN202310934719.1A
Authority: CN
Inventors: 肖亮; 张安辉; 冯伟
Original assignee: Dongguan Becky Electronic Technology Co ltd
Current assignee: Dongguan Becky Electronic Technology Co ltd
Priority date: 2023-07-27
Filing date: 2023-07-27
Publication date: 2023-10-10

Abstract

The application belongs to the technical field of constant current power supplies, and particularly relates to a high-precision constant current power supply circuit which comprises a main control circuit, a high-frequency switch circuit, an integral compensation circuit and a current detection circuit; the main control circuit comprises a main control chip U1, the high-frequency switch circuit is connected with the main control chip U1, the integral compensation circuit is connected with the main control chip U1 and the high-frequency switch circuit, and the current detection circuit is connected with the high-frequency switch circuit and the main control chip U1. By arranging the integral compensation circuit in the circuit, constant current control is realized through analog signal integration, so that the high precision of the circuit is realized with extremely low labor cost and production cost, and the circuit has the advantages of strong flexibility and good stability. By arranging the temperature compensation circuit, the temperature characteristic of the diode is utilized, the diode is reduced in voltage and linearly reduced in temperature, so that the output current is linearly increased in temperature, the current error generated by high-temperature aging current dropping can be effectively regulated, and the problem of output constant current precision is further improved.

Description

High-precision constant-current power supply circuit

Technical Field

The application belongs to the technical field of constant current power supplies, and particularly relates to a high-precision constant current power supply circuit.

Background

The current precision of constant current products is required to be higher in the field of illumination, for example, a plurality of lamp manufacturers require 1% constant current precision for the consistency of the required light efficiency and brightness. However, the precision requirement cannot be met for the semiconductors and components of the traditional process in terms of hardware, and the precision requirement can only be realized by selecting or other methods, so that the labor cost and the repetition period are greatly increased; and for software, various manufacturers adopt an upper computer to change analog level through software to realize high precision, the software upper computer is controlled to adopt data communication feedback adjustment, the production test cost is higher, meanwhile, the flexibility is not strong, the operation is complex, and the labor cost is higher.

There is a need to devise a new solution to the above-mentioned problems.

Disclosure of Invention

The application aims to provide a high-precision constant-current power supply circuit, and aims to solve the technical problems of low precision, high cost and complex operation of the constant-current power supply circuit in the prior art.

In order to achieve the above purpose, the embodiment of the application provides a high-precision constant current power supply circuit, which comprises a main control circuit, a high-frequency switch circuit, an integral compensation circuit and a current detection circuit; the main control circuit comprises a main control chip U1, the high-frequency switch circuit is connected with the main control chip U1, the integral compensation circuit is connected with the main control chip U1 and the high-frequency switch circuit, and the current detection circuit is connected with the high-frequency switch circuit and the main control chip U1.

As a preferable scheme, the temperature compensation circuit comprises a resistor R2 and a capacitor C1, wherein a first end of the resistor R2 is connected with a CS pin of the main control chip U1, a first end of the capacitor C1 is connected with a second end of the resistor R2, and a second end of the capacitor C1 is connected with the high-frequency switch circuit.

As a preferred scheme, the high-frequency switch circuit comprises a MOS tube Q1, a diode D4, a filter capacitor CE3 and a common-mode inductor L1, wherein a base electrode of the MOS tube Q1 is connected with a VG1 pin of a main control chip U1 and a second end of the capacitor C1, an anode of the diode D4 is connected with a drain electrode of the MOS tube Q1, an anode of the filter capacitor CE3 is connected with a cathode of the diode D4, a first end of the common-mode inductor L1 is connected with the drain electrode of the MOS tube Q1 and the anode of the diode D4, a second end of the common-mode inductor L1 is connected with the cathode of the filter capacitor CE3, and a third end of the common-mode inductor L1 is connected with the current detection circuit.

As a preferable scheme, the integral compensation circuit further includes a discharge resistor R3, a first end of the discharge resistor R3 is connected to a second end of the capacitor C1, and a second end of the discharge resistor R3 is connected to a source of the MOS transistor Q1.

As a preferable scheme, the high-frequency switch circuit further comprises a drive circuit, the drive circuit comprises a diode D1 and a resistor R1, the positive electrode of the diode D1 is connected with the base electrode of the MOS tube Q1, the negative electrode of the diode D1 is connected with the VG1 pin of the main control chip U1, and the resistor R1 is connected in parallel with two ends of the diode D1.

As a preferable mode, the current detection circuit includes a resistor RS2 and a resistor RS1; a first end of the resistor RS2 is connected with a CS pin of the main control chip U1 and a source electrode of the MOS tube Q1, and a second end of the resistor RS2 is connected with a third end of the common mode inductor L1; the resistor RS1 is connected in parallel to two ends of the resistor RS 2.

As a preferable scheme, the zero-crossing detection circuit comprises a resistor R7 and a resistor R6, wherein the first end of the resistor R7 is connected with the second end of the resistor RS2, the first end of the resistor R6 is connected with the second end of the resistor R7 and the ZCS pin of the main control chip U1, and the second end of the resistor R6 is connected with the third end of the common-mode inductor L1.

As a preferable scheme, the temperature compensation circuit is further included, and the temperature compensation circuit is connected with the main control chip U1 and the integrated compensation circuit.

As a preferable scheme, the temperature compensation circuit comprises a resistor R5 and a diode D2, wherein a first end of the resistor R5 is connected with a CS pin of the main control chip U1, and a positive electrode of the diode D2 is connected with a second end of the resistor R5.

As a preferable scheme, the circuit also comprises an RC filter circuit, wherein the RC filter circuit comprises a resistor R4 and a capacitor C2, the first end of the resistor R4 is connected with the current detection circuit, the second end of the resistor R4 is connected with the main control chip U1, the first end C2 of the capacitor is connected with the first end of the resistor R4, and the second end of the capacitor C2 is connected with the current detection circuit

The above technical scheme in the high-precision constant-current power supply circuit provided by the embodiment of the application has at least one of the following technical effects:

by arranging the integral compensation circuit in the circuit, constant current control is realized through analog signal integration, so that the high precision of the circuit is realized with extremely low labor cost and production cost, and the circuit has the advantages of strong flexibility and good stability.

By arranging the temperature compensation circuit, the temperature characteristic of the diode is utilized, the diode is reduced in voltage and linearly reduced in temperature, so that the output current is linearly increased in temperature, the current error generated by high-temperature aging current dropping can be effectively regulated, and the problem of output constant current precision is further improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a circuit schematic diagram of a high-precision constant current power supply circuit provided by an embodiment of the application;

FIG. 2 is a diagram of the working state of the circuit before the integral compensation circuit is added according to the embodiment of the application;

FIG. 3 is a circuit operation state diagram after the integration compensation circuit is added according to the embodiment of the present application;

wherein, each reference sign in the figure:

100-a master control circuit; 200-a high frequency switching circuit; 210-a driving circuit; 300-integral compensation circuit; 400-a current detection circuit; 500-temperature compensation circuit; 600-zero crossing detection circuit; 700-RC filter circuit.

Detailed Description

Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and intended to illustrate embodiments of the application and should not be construed as limiting the application.

In the description of the embodiments of the present application, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate description of the embodiments of the present application and simplify description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the embodiments of the present application, the meaning of "plurality" is two or more, unless explicitly defined otherwise.

In the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like are to be construed broadly and include, for example, either permanently connected, removably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to specific circumstances.

In one embodiment of the application, as shown in fig. 1, a high-precision constant-current power supply circuit is provided, which can be widely applied to flyback, double-tube flyback and BUCK, BOOST, BUCK-BOOST topologies adopting primary side feedback. The high-precision constant-current power supply circuit comprises a main control circuit 100, a high-frequency switch circuit 200, an integral compensation circuit 300 and a current detection circuit 400. The main control circuit 100 comprises a main control chip U1, the high-frequency switch circuit 200 is connected with the main control chip U1, the integral compensation circuit 300 is connected with the main control chip U1 and the high-frequency switch circuit 200, and the current detection circuit 400 is connected with the high-frequency switch circuit 200 and the main control chip U1.

The high-frequency switch circuit 200 includes a MOS transistor Q1, a diode D4, a filter capacitor CE3, and a common-mode inductor L1. The base electrode of the MOS tube Q1 is connected with the VG1 pin of the main control chip U1 and the second end of the capacitor C1; the anode of the diode D4 is connected with the drain electrode of the MOS tube Q1; the positive electrode of the filter capacitor CE3 is connected with the negative electrode of the diode D4; the first end of the common-mode inductor L1 is connected to the drain electrode of the MOS transistor Q1 and the positive electrode of the diode D4, the second end of the common-mode inductor L1 is connected to the negative electrode of the filter capacitor CE3, and the third end of the common-mode inductor L1 is connected to the current detection circuit 400.

In this embodiment, the high-frequency switch circuit 200 further includes a driving circuit 210, the driving circuit 210 includes a diode D1 and a resistor R1, the positive electrode of the diode D1 is connected to the base electrode of the MOS transistor Q1, the negative electrode of the diode D1 is connected to the VG1 pin of the main control chip U1, and the resistor R1 is connected in parallel to two ends of the diode D1.

The integral compensation circuit 300 includes a resistor R2 and a capacitor C1. The first end of the resistor R2 is connected with the CS pin of the main control chip U1, the first end of the capacitor C1 is connected with the second end of the resistor R2, and the second end of the capacitor C1 is connected with the high-frequency switch circuit 200.

In this embodiment, the integral compensation circuit 300 further includes a discharge resistor R3, a first end of the discharge resistor R3 is connected to the second end of the capacitor C1, and a second end of the discharge resistor R3 is connected to the source of the MOS transistor Q1. The MOS transistor Q1 is prevented from outputting high level in a suspended state by the arrangement of the discharge resistor R3.

The current detection circuit 400 includes a resistor RS2 and a resistor RS1. A first end of the resistor RS2 is connected with a CS pin of the main control chip U1 and a source electrode of the MOS tube Q1, and a second end of the resistor RS2 is connected with a third end of the common mode inductor L1; the resistor RS1 is connected in parallel to two ends of the resistor RS 2.

The working principle of the embodiment is described in detail as follows:

the application is realized by utilizing the principle of superposition of driving signals and RC integration. Taking the critical mode BUCK type topology as an example.

The circuit operation waveforms are shown in fig. 2 when the integrated compensation circuit 300 is not added.

After the integration compensation circuit 300 is added, as shown in fig. 3.

At time t 1: the main control chip U1 outputs a duty ratio, and the MOS tube Q1 is conducted and forms a loop by the filter capacitor CE3, the common mode inductor L1, the MOS tube Q1, the resistor RS1 and the resistor RS 2. The capacitor C1 and the resistor R2 integrate circuit form a compensation network to charge the common-mode inductor L1, and the current at two ends of the common-mode inductor L1 gradually rises from zero, as shown in fig. 3. Because the capacitor C1 and the resistor R2 are added, when PWM signals are output, a PWM signal which is in phase with the PWM signals is generated at the joint of the capacitor C1 and the resistor R2 by utilizing the on-high frequency resistance low frequency principle of the capacitor, and the switching frequency and the on-time are consistent with the PWM output, and then the compensation voltage value is reduced after the PWM signal passes through the resistor R2 (the voltage of the Vsen detection pin is generally smaller than 1V, so that the value of the resistor R2 is K level), and the voltage is given to the Isen pin. At this time, the voltage of the Isen pin is increased by a certain voltage value and is the same as the current direction, the two ends of the resistor RS1 and the resistor RS2 are still triangular wave current waveforms gradually rising from zero, and the voltage Vrc+Vrs1/2 of Vsen after the integrated compensation of the capacitor C1 and the resistor R2 is performed, so that the output current is slightly lower than that when the capacitor C1 and the resistor R2 are not added. After the circuit is added for linear adjustment rate difference, as BUCK duty ratio=Vout/Vin, square wave compensation voltage values at two ends of the resistor R2 can change along with the duty ratio change when the duty ratio changes, and the on time becomes long when the duty ratio becomes large, so that the platform value at the tail end of the resistor R2 is unchanged but the slope becomes smooth, and the voltages of the two ends of the resistor RS1 and the resistor RS2 acted by Ipk are also smoothed, so that the slope becomes steep when Vsen is compared with that when the circuit is not added, the set value is more easily reached, and the PWM signal is closed. Similarly, when the duty ratio is reduced, the slope of the Ipk is steeped, the slope is changed after the Isen foot pad is applied with voltage, and the switching frequency of the duty ratio is slightly changed after the Isen foot pad is applied with voltage, so that the linear adjustment rate of the switching frequency is adjusted cycle by cycle. The working principle of the load adjustment rate is the same as that of the linear adjustment rate, the basic principle is that the voltage is input into an Isen foot pad, so that the slope of a voltage signal of the Isen foot pad is steeped, the voltage slope is changed, the compensation voltage value of the Isen foot pad is adjusted, the slope, time and amplitude are effectively changed by using the duty ratio, and the switching tube is controlled to be switched on and off, so that high-precision output is realized, the current waveforms of the switching tube and the BUCK inductor are unchanged, the common-mode inductor L1 reaches the maximum value at the fixed time t1, and the PWM signal is switched off.

At time t 2: the output of the main control chip U1 is closed, the MOS tube Q1 is cut off, a main loop is formed by the filter capacitor CE3, the common mode inductor L1 and the diode D4, the resistor R6 and the resistor R7 form a detection loop, the common mode inductor L1 is charged to the maximum value at the moment t1, at this time, the common mode inductor L1 starts to discharge, and the current at two ends of the common mode inductor L1 gradually decreases from the maximum value, as shown in fig. 3. When the inductance current is reduced to zero, the next switching cycle starts, and for the primary detection type main control chip U1, the maximum voltage Vsen voltage is mainly used for controlling the duty ratio to be closed when the switching tube is turned on, and the resistance R6 and the resistance R7 are used for detecting the switching of the inductance current to control the duty ratio, so that constant current in each cycle is realized.

In another embodiment of the present application, as shown in fig. 1, the high-precision constant current power supply circuit further includes a temperature compensation circuit 500, and the temperature compensation circuit 500 is connected to the main control chip U1 and the integrated compensation circuit 300. The temperature compensation circuit 500 includes a resistor R5 and a diode D2, wherein a first end of the resistor R5 is connected to the CS pin of the main control chip U1, and an anode of the diode D2 is connected to a second end of the resistor R5.

The embodiment is realized by utilizing the temperature characteristic of a diode, when the current is reduced according to the I-V characteristic of the diode, the conduction voltage drop is reduced, the conduction voltage drop is divided by the resistor R5 and the diode D2 in series and then is divided by the resistor R4 after the conduction voltage drop is reduced, so that the purpose of improving the output current when the temperature is high is realized, when the temperature of the diode is increased, VF gradually decreases, and the voltage drop is caused when the resistor R5 and the diode D2 are connected in series and then the voltage rising duty ratio of the two ends of the resistor RS1 and the resistor RS2 is increased, and the output current is increased because Vsen is kept unchanged, and the calculation is as follows: vsen= (vrc+vrs1/2)/(r5+rd2+r4), and the diode is reduced in voltage and linearly lowered in temperature, so that the output current is linearly raised in temperature, the current error generated by high-temperature aging current dropping can be effectively regulated, and the problem of constant current precision of output is further improved.

In another embodiment of the present application, as shown in fig. 1, the high precision constant current power supply circuit further includes a zero crossing detection circuit 600, where the zero crossing detection circuit 600 includes a resistor R7 and a resistor R6, a first end of the resistor R7 is connected to a second end of the resistor RS2, a first end of the resistor R6 is connected to the second end of the resistor R7 and a ZCS pin of the master control chip U1, and a second end of the resistor R6 is connected to a third end of the common mode inductor L1.

In another embodiment of the present application, as shown in fig. 1, the high-precision constant-current power supply circuit further includes an RC filter circuit 700, where the RC filter circuit 700 includes a resistor R4 and a capacitor C2, a first end of the resistor R4 is connected to the current detection circuit 400, a second end of the resistor R4 is connected to the main control chip U1, a first end C2 of the capacitor is connected to the first end of the resistor R4, and a second end of the capacitor C2 is connected to the current detection circuit 400.

It should be noted that, the present application aims to protect the circuit structure, and for the program control portion, those skilled in the art should select a suitable circuit and chip according to the type of each chip or the need in the present application and perform appropriate programming, so as to implement the corresponding program control function in the present application, so that the present application is partly a mature and shaped technology in the prior art, and is not the protection focus of the present application, so that the present application does not specifically describe the control portion.

The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the application.

Claims

1. The high-precision constant-current power supply circuit is characterized by comprising a main control circuit, a high-frequency switch circuit, an integral compensation circuit and a current detection circuit; the main control circuit comprises a main control chip U1, the high-frequency switch circuit is connected with the main control chip U1, the integral compensation circuit is connected with the main control chip U1 and the high-frequency switch circuit, and the current detection circuit is connected with the high-frequency switch circuit and the main control chip U1.

2. The high-precision constant-current power supply circuit according to claim 1, wherein the temperature compensation circuit comprises a resistor R2 and a capacitor C1, a first end of the resistor R2 is connected with a CS pin of the main control chip U1, a first end of the capacitor C1 is connected with a second end of the resistor R2, and a second end of the capacitor C1 is connected with the high-frequency switching circuit.

3. The high-precision constant-current power supply circuit according to claim 2, wherein the high-frequency switching circuit comprises a MOS tube Q1, a diode D4, a filter capacitor CE3 and a common-mode inductor L1, wherein a base electrode of the MOS tube Q1 is connected with a VG1 pin of the main control chip U1 and a second end of the capacitor C1, an anode of the diode D4 is connected with a drain electrode of the MOS tube Q1, an anode of the filter capacitor CE3 is connected with a cathode of the diode D4, a first end of the common-mode inductor L1 is connected with the drain electrode of the MOS tube Q1 and an anode of the diode D4, a second end of the common-mode inductor L1 is connected with the cathode of the filter capacitor CE3, and a third end of the common-mode inductor L1 is connected with the current detection circuit.

4. The high-precision constant current power supply circuit according to claim 3, wherein the integral compensation circuit further comprises a discharge resistor R3, a first end of the discharge resistor R3 is connected with a second end of the capacitor C1, and a second end of the discharge resistor R3 is connected with a source electrode of the MOS tube Q1.

5. The high-precision constant-current power supply circuit according to claim 3, wherein the high-frequency switching circuit further comprises a driving circuit, the driving circuit comprises a diode D1 and a resistor R1, the positive electrode of the diode D1 is connected with the base electrode of the MOS tube Q1, the negative electrode of the diode D1 is connected with the VG1 pin of the main control chip U1, and the resistor R1 is connected in parallel with two ends of the diode D1.

6. The high-precision constant-current power supply circuit according to claim 3, wherein the current detection circuit comprises a resistor RS2 and a resistor RS1; a first end of the resistor RS2 is connected with a CS pin of the main control chip U1 and a source electrode of the MOS tube Q1, and a second end of the resistor RS2 is connected with a third end of the common mode inductor L1; the resistor RS1 is connected in parallel to two ends of the resistor RS 2.

7. The high-precision constant-current power supply circuit according to claim 6, further comprising a zero-crossing detection circuit, wherein the zero-crossing detection circuit comprises a resistor R7 and a resistor R6, a first end of the resistor R7 is connected with a second end of the resistor RS2, a first end of the resistor R6 is connected with the second end of the resistor R7 and a ZCS pin of the master control chip U1, and a second end of the resistor R6 is connected with a third end of the common-mode inductor L1.

8. The high-precision constant-current power supply circuit according to any one of claims 1 to 6, further comprising a temperature compensation circuit, wherein the temperature compensation circuit is connected with the main control chip U1 and the integral compensation circuit.

9. The high-precision constant current power supply circuit according to claim 7, wherein the temperature compensation circuit comprises a resistor R5 and a diode D2, a first end of the resistor R5 is connected with a CS pin of the main control chip U1, and an anode of the diode D2 is connected with a second end of the resistor R5.

10. The high-precision constant-current power supply circuit according to any one of claims 1 to 6, further comprising an RC filter circuit, wherein the RC filter circuit comprises a resistor R4 and a capacitor C2, a first end of the resistor R4 is connected to the current detection circuit, a second end of the resistor R4 is connected to the main control chip U1, a first end C2 of the capacitor is connected to the first end of the resistor R4, and a second end of the capacitor C2 is connected to the current detection circuit.