A constant voltage and current limiting control loop

Abstract

The present invention provides a constant voltage and current limiting control loop, comprising: a voltage feedback loop regulator, a current loop resistor, a diode, and a current feedback loop regulator; wherein the output end of the current feedback loop regulator is connected to the positive electrode of the diode, the negative electrode of the diode is connected to the first end of the current loop resistor, and the second end of the current loop resistor is connected to the voltage feedback loop regulator; when the output current signal sampled by the current feedback loop regulator is less than a reference voltage, the diode is reversely cut off, and the constant voltage and current limiting control loop is completely controlled by the voltage feedback loop regulator to achieve constant voltage control output; when the output current signal sampled by the current feedback loop regulator is greater than the reference voltage, the diode is forwardly conducted, and a compensation current is sent to the voltage feedback loop regulator based on the current loop resistor and the diode, so as to achieve an output current equal to a set value of the current loop.

Description

Technical Field

[0001] The present invention relates to the field of new energy electric control technology, and in particular to a constant voltage and current limiting control loop. Background Art

[0002] The market demand for the output of DC output power modules is: the ability to control output voltage and output current. For this reason, for lithium battery charging applications, constant voltage and current limiting control is generally required, that is, when the maximum charging voltage is not reached, constant current charging is used, and when the maximum voltage is reached, constant voltage output is used. This requires a stable and reliable control circuit to achieve this. Summary of the invention

[0003] The present invention is based on at least one of the above technical problems and proposes a new constant voltage and current limiting control loop. The entire circuit structure is reasonably designed, has good stability and reliable operation.

[0004] In view of this, the present invention proposes a new constant voltage and current limiting control loop, including: a voltage feedback loop regulator, a current loop resistor, a diode, and a current feedback loop regulator; wherein the output end of the current feedback loop regulator is connected to the positive electrode of the diode, the negative electrode of the diode is connected to the first end of the current loop resistor, and the second end of the current loop resistor is connected to the voltage feedback loop regulator; when the output current signal sampled by the current feedback loop regulator is less than a reference voltage, the diode is reversely cut off, and the constant voltage and current limiting control loop is completely controlled by the voltage feedback loop regulator to achieve constant voltage control output; when the output current signal sampled by the current feedback loop regulator is greater than the reference voltage, the diode is forward-conducted, and a compensation current is sent to the voltage feedback loop regulator based on the current loop resistor and the diode to achieve an output current equal to the set value of the current loop.

[0005] In the above technical solution, preferably, the voltage feedback loop regulator includes an isolation optocoupler, a power supply resistor, an electrostatic discharge resistor, a controllable precision voltage regulator, a first voltage loop compensation capacitor, a second voltage loop compensation capacitor, a voltage loop compensation resistor, a first sampling voltage divider resistor and a second sampling voltage divider resistor; the current feedback loop regulator includes an operational amplifier, a first current loop compensation capacitor, a second current loop compensation capacitor, a current loop compensation resistor, a first reference voltage divider resistor, a second reference voltage divider resistor, and a reference filter capacitor; wherein the output end of the operational amplifier serves as the output end of the current feedback loop regulator, and the second end of the current loop resistor is connected to the control end of the controllable precision voltage regulator in the voltage feedback loop regulator.

[0006] Through the above technical scheme, a voltage feedback loop regulator and a current feedback loop regulator are designed. Based on the comparison result of the output current signal sampled by the current feedback loop regulator and the reference voltage, the constant voltage and steady current output of the entire loop are regulated. The entire circuit structure is reasonably designed, with good stability and reliable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A structural schematic diagram of a constant voltage and current limiting control circuit according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0008] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0009] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0010] In this embodiment, the constant voltage and current limiting control loop includes: a voltage feedback loop regulator, a current loop resistor, a diode, and a current feedback loop regulator. The specific components and the electrical connection relationship between them are as follows: Figure 1 As shown:

[0011] 1). The voltage feedback loop regulator includes: an isolation optocoupler U1, a power supply resistor R1, an electrostatic discharge resistor R2, a controllable precision voltage regulator U2 (TL431 controllable precision voltage regulator can be selected), a first voltage loop compensation capacitor C1, a second voltage loop compensation capacitor C2, a voltage loop compensation resistor R3, a first sampling voltage divider resistor R4, a second sampling voltage divider resistor R5, a voltage feedback loop regulator samples the output voltage Vout, and the FB and AGND output by U1 are sent to the chip feedback port;

[0012] 2). The current feedback loop regulator includes an operational amplifier U3, a first current loop compensation capacitor C3, a second current loop compensation capacitor C4, a current loop compensation resistor R7, a first reference voltage divider resistor R8, a second reference voltage divider resistor R9, and a reference filter capacitor C5. The reference uses the inverting end of the operational amplifier, and the current sampling signal uses the non-inverting end of the operational amplifier. The feedback network is connected across the inverting end of the operational amplifier and the output of the operational amplifier. The current feedback loop regulator samples the output current IS_out. The current feedback loop regulator is connected to the voltage feedback loop regulator through a diode D1 in series with the current loop resistor R6, and the connection point is the U2 control end of the voltage feedback regulator.

[0013] The working principle of the whole circuit is:

[0014] 1. When the sampling current signal IS_out is less than the reference voltage, the op amp outputs a low level, the diode D1 is reversely cut off, the current loop does not work, and the loop is completely controlled by the voltage feedback network, that is, a constant voltage control output is achieved;

[0015] 2. When the sampling current signal IS_out is greater than the reference voltage, the output voltage of the operational amplifier of the current feedback loop regulator increases, and the compensation current is transmitted to R4 and R5 of the voltage loop through D1 and R6, which is equivalent to increasing the resistance of R4 and lowering the voltage limit point. Through the dynamic adjustment of the loop, the output current is equal to the set value of the current loop; among which, the reference voltage is the voltage Vref divided by R8 and R9 to the reverse section of the operational amplifier.

[0016] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A constant voltage and current limiting control loop, It is characterized in that include: Voltage feedback loop regulator, current loop resistor, diode, current feedback loop regulator; Wherein, the output end of the current feedback loop regulator is connected to the anode of the diode, the cathode of the diode is connected to the first end of the current loop resistor, and the second end of the current loop resistor is connected to the voltage feedback loop regulator; When the output current signal sampled by the current feedback loop regulator is less than the reference voltage, the diode is reversely cut off, and the constant voltage current limiting control loop is completely controlled by the voltage feedback loop regulator to achieve constant voltage control output; when the output current signal sampled by the current feedback loop regulator is greater than the reference voltage, the diode is forward-conducted, and based on the current loop resistance and the diode compensation current is sent to the voltage feedback loop regulator to achieve an output current equal to the set value of the current loop.

2. The constant voltage and current limiting control loop according to claim 1, It is characterized in that The voltage feedback loop regulator includes an isolation optocoupler, a power-taking resistor, an electrostatic discharge resistor, a controllable precision voltage regulator, a first voltage loop compensation capacitor, a second voltage loop compensation capacitor, a voltage loop compensation resistor, a first sampling voltage divider resistor and a second sampling voltage divider resistor; the current feedback loop regulator includes an operational amplifier, a first current loop compensation capacitor, a second current loop compensation capacitor, a current loop compensation resistor, a first reference voltage divider resistor, a second reference voltage divider resistor, and a reference filter capacitor; wherein the output end of the operational amplifier serves as the output end of the current feedback loop regulator, and the second end of the current loop resistor is connected to the control end of the controllable precision voltage regulator in the voltage feedback loop regulator.

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