Low-power-consumption circuit used under BUCK topology no-load condition

Abstract

The utility model discloses a low-power-consumption circuit used under a BUCK topology no-load condition, which is characterized in that a node is arranged on a connecting line between an output end of a BUCK power circuit and an output voltage end of a BUCK topology circuit, a branch is led out to be connected with one end of an output capacitor C1, and the other end of the output capacitor C1 is grounded; the input end of the output voltage floating charge circuit is connected with the input voltage end of the BUCK topology circuit, and the output end of the output voltage floating charge circuit is connected with the output voltage end of the BUCK topology circuit; the output voltage floating charge circuit is used for providing floating charge voltage higher than the output voltage of the BUCK topology circuit under the steady-state working condition for the output capacitor C1 under the BUCK topology no-load condition; the output voltage feedback loop is connected with the output end of the BUCK topology circuit, and the output end of the output voltage feedback loop is connected with the BUCK control circuit. According to the application, the low power consumption requirement under the no-load condition is met, the structure is simple, and the number of components is small.

Description

Technical Field

[0001] The present application relates to the technical field of BUCK converters, and in particular to a low-power circuit for use in a BUCK topology under no-load conditions. Background Art

[0002] In the field of new energy electric vehicles, in order to ensure the safety and reliability of the battery charging and discharging process during the use of electric vehicles, and also to ensure the service life of the battery, the power balancer has become an important component of the battery charge and discharge management system. The power balancer must not only meet the management requirements of battery charging and discharging, but also meet the requirements of low power consumption under no-load conditions.

[0003] In the design of the power balancer BUCK low-power circuit, the output current value can be collected through the MCU, and when it is lower than the set current value, the BUCK topology circuit can be turned off through program control, but this design scheme has complex circuit design and high cost. The output current value or output voltage value can also be sampled in real time through a comparator, and then fed back to the BUCK control circuit after logical judgment through an operational amplifier, but this design scheme has a large number of components and occupies a large board area. Utility Model Content

[0004] Based on this, in order to solve the above technical problems, a low-power circuit for BUCK topology under no-load conditions is provided, so that the BUCK low-power circuit can meet the low-power requirements under no-load conditions with a simple structure and a small number of components.

[0005] A low-power circuit for a BUCK topology under no-load conditions, comprising a BUCK topology circuit and a BUCK control circuit, wherein the BUCK topology circuit comprises a BUCK power circuit and an output capacitor C1; the BUCK control circuit is connected to the BUCK topology circuit; the output end of the BUCK topology circuit is an output voltage end; an input end of the BUCK topology circuit is an input voltage end; a node is arranged on a connection line between the output end of the BUCK power circuit and the output voltage end of the BUCK topology circuit, a branch is led out and connected to one end of the output capacitor C1, and the other end of the output capacitor C1 is grounded;

[0006] The circuit further includes: an output voltage floating charging circuit and an output voltage feedback loop; the input end of the output voltage floating charging circuit is connected to the input voltage end of the BUCK topology circuit, and the output end of the output voltage floating charging circuit is connected to the output voltage end of the BUCK topology circuit; the output voltage floating charging circuit is used to provide a floating charging voltage higher than the output voltage under the steady-state working condition of the BUCK topology circuit to the output capacitor C1 under the no-load condition of the BUCK topology;

[0007] The output voltage feedback loop is connected to the output end of the BUCK topology circuit, and the output end of the output voltage feedback loop is connected to the BUCK control circuit.

[0008] In the above solution, optionally, the output voltage feedback loop includes an operational amplifier U1, a resistor R1, a resistor R2, a resistor R3, and a resistor R4;

[0009] The resistor R1 is connected in series with the resistor R2, the resistor R3 is connected in series with the resistor R4, the end of the resistor R1 away from R2 is connected to the output voltage end of the BUCK topology circuit, the end of the resistor R2 away from the resistor R1 is connected to the end of the resistor R4 away from the resistor R3 and then grounded; the end of the resistor R3 away from the resistor R4 is the input voltage end; the same-direction input end of the operational amplifier U1 is connected to the connection line between the resistor R1 and the resistor R2, and the reverse input end of the operational amplifier U1 is connected to the connection line between the resistor R3 and the resistor R4; the output end of the operational amplifier U1 is connected to the BUCK control circuit.

[0010] In the above solution, further optionally, the output voltage floating charging circuit includes a resistor R5; the input end of the resistor R5 is connected to the input voltage end of the BUCK topology circuit, and the output end of the resistor R5 is connected to the output voltage end of the BUCK topology circuit.

[0011] In the above scheme, further optionally, the output voltage floating charging circuit includes a resistor R6, a resistor R7, a resistor R8, a diode D1 and a transistor Q1;

[0012] The resistor R6, the diode D1 and the resistor R7 are connected in series in sequence, and the end of the resistor R7 away from the diode D1 is grounded; the end of the resistor R6 away from the diode D1 is connected to the input voltage end of the BUCK topology circuit; a first node is set on the connection line between the resistor R6 and the diode D1, a first branch is drawn from the first node and connected to the base of the transistor Q1, a second node is set on the connection line between the resistor R6 and the input voltage end of the BUCK topology circuit, a second branch is drawn from the second node and connected to the resistor R8 and the collector of the transistor Q1 in sequence; the emitter of the transistor Q1 is connected to the output voltage end of the BUCK topology circuit; the resistor R6 and the resistor R7 have the same resistance value, which is 10K to 100K.

[0013] In the above solution, further optionally, the output voltage floating charging circuit includes a resistor R9, a resistor R10, a resistor R11, a voltage regulator ZD1 and a transistor Q2;

[0014] The resistor R9, the voltage regulator ZD1 and the resistor R10 are connected in series in sequence, and one end of the resistor R10 away from the voltage regulator ZD1 is grounded; one end of the resistor R9 away from the voltage regulator ZD1 is connected to the input voltage end of the BUCK topology circuit; a third node is set on the connection line between the resistor R9 and the voltage regulator ZD1, a third branch is drawn from the third node and connected to the base of the transistor Q2, a fourth node is set on the connection line between the resistor R9 and the input voltage end of the BUCK topology circuit, a fourth branch is drawn from the fourth node and connected to the resistor R11 and the collector of the transistor Q2 in sequence; the emitter of the transistor Q2 is connected to the output voltage end of the BUCK topology circuit; the resistor R9 and the resistor R10 have the same resistance value, which is 10K to 100K.

[0015] In the above solution, further optionally, the resistance of the resistor R5 is:

[0016]

[0017] Among them, R1 and R2 are the resistance values ​​of the sampling resistors R1 and R2 in the output voltage feedback loop, Uin is the input voltage value of the BUCK topology circuit, and Uo is the output voltage of the BUCK topology circuit.

[0018] This application has at least the following beneficial effects:

[0019] This application uses an output voltage floating charging circuit to float charge the output capacitor under the no-load condition of the BUCK topology, and sets the floating charging voltage value so that the set voltage value is slightly higher than the output voltage value under the steady-state working condition of the BUCK topology. When the output voltage feedback loop under the no-load condition of the BUCK topology collects that the output voltage is higher than the steady-state working output voltage value of the BUCK topology, it will be fed back to the BUCK control circuit to turn off the drive output, thereby achieving the purpose of low power consumption under the no-load condition of the BUCK topology. Therefore, the circuit design of this application is simple, the structure is simple, the number of components is small, and the layout occupies a small space. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A circuit schematic diagram of a low power consumption circuit for a BUCK topology under no-load conditions is provided for one embodiment of the present application;

[0021] Figure 2 Three specific circuit structure diagrams of an output voltage floating charging circuit are provided for one embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] BUCK topology low power consumption circuit principle under no-load condition: principle block diagram as shown Figure 1 As shown, in the general BUCK topology circuit, the output voltage is stabilized at the set value by setting the output voltage sampling value in the output voltage feedback loop. When the output is in the no-load state, due to the self-discharge of the output capacitor, when the output capacitor voltage is discharged to below the set value, the BUCK topology circuit enters the working state to charge the output capacitor, and additional power consumption is generated during this repeated discharge and charging process. Therefore, the present application proposes to design an output voltage floating charging circuit for charging the output capacitor.

[0024] In one embodiment, Figure 1 As shown, a low-power circuit for BUCK topology under no-load conditions is provided, including a BUCK topology circuit and a BUCK control circuit, wherein the BUCK topology circuit includes a BUCK power circuit and an output capacitor C1; the BUCK control circuit is connected to the BUCK topology circuit; the output end of the BUCK topology circuit is an output voltage end; an input end of the BUCK topology circuit is an input voltage end; a node is set on a connection line between the output end of the BUCK power circuit and the output voltage end of the BUCK topology circuit, and a branch is led out to be connected to one end of the output capacitor C1, and the other end of the output capacitor C1 is grounded;

[0025] The circuit further includes: an output voltage floating charging circuit and an output voltage feedback loop; the input end of the output voltage floating charging circuit is connected to the input voltage end of the BUCK topology circuit, and the output end of the output voltage floating charging circuit is connected to the output voltage end of the BUCK topology circuit; the output voltage floating charging circuit is used to provide a floating charging voltage higher than the output voltage under the steady-state working condition of the BUCK topology circuit to the output capacitor C1 under the no-load condition of the BUCK topology;

[0026] The output voltage feedback loop is connected to the output end of the BUCK topology circuit, and the output end of the output voltage feedback loop is connected to the BUCK control circuit.

[0027] Specifically, in the BUCK topology application, in order to obtain the required output voltage, the BUCK topology circuit adjusts the duty cycle of the BUCK control circuit through the output voltage feedback loop. Under the condition of no-load output load, due to the self-discharge of the output capacitor, when the output capacitor voltage is discharged to a value lower than the set value, the BUCK topology circuit enters the working state to charge the output capacitor, and additional power consumption is generated during this repeated discharge and charging process. The output voltage floating charging circuit added in this embodiment is used to float charge the output capacitor, and the output voltage drop caused by the self-discharge of the capacitor is offset by floating charging the output capacitor. At the same time, by setting and adjusting the size of the floating charging voltage, the output capacitor floating charging voltage is slightly higher than the steady-state output voltage, and then the BUCK control circuit is driven to be closed through the voltage sampling feedback loop, so as to achieve the design requirement of low power consumption under no-load conditions.

[0028] The above-mentioned low-power circuit for BUCK topology under no-load conditions is used to float charge the output capacitor under BUCK topology no-load conditions through the output voltage floating charging circuit, and the set voltage value is set to be slightly higher than the output voltage value under the steady-state working condition of the BUCK topology. When the output voltage feedback loop under the no-load condition of the BUCK topology collects that the output voltage is higher than the steady-state working output voltage value of the BUCK topology, it will be fed back to the BUCK control circuit to turn off the drive output, thereby achieving the purpose of low power consumption under the no-load condition of the BUCK topology. Therefore, the circuit design of this application is simple, the structure is simple, the number of components is small, and the layout occupies a small space.

[0029] In one embodiment, Figure 1 As shown, the output voltage feedback loop includes an operational amplifier U1, a resistor R1, a resistor R2, a resistor R3, and a resistor R4;

[0030] The resistor R1 is connected in series with the resistor R2, the resistor R3 is connected in series with the resistor R4, the end of the resistor R1 away from R2 is connected to the output voltage end of the BUCK topology circuit, the end of the resistor R2 away from the resistor R1 is connected to the end of the resistor R4 away from the resistor R3 and then grounded; the end of the resistor R3 away from the resistor R4 is the input voltage end; the same-direction input end of the operational amplifier U1 is connected to the connection line between the resistor R1 and the resistor R2, and the reverse input end of the operational amplifier U1 is connected to the connection line between the resistor R3 and the resistor R4; the output end of the operational amplifier U1 is connected to the BUCK control circuit.

[0031] In one embodiment, Figure 2 As shown in (a), the output voltage floating charging circuit includes a resistor R5; an input end of the resistor R5 is connected to an input voltage end of the BUCK topology circuit, and an output end of the resistor R5 is connected to an output voltage end of the BUCK topology circuit.

[0032] Specifically, the output voltage floating charge circuit is implemented using a resistor; the first end of the resistor R5 in the output voltage floating charge circuit is connected to the input voltage end; the second end of the resistor R5 in the output voltage floating charge circuit is connected to the output voltage end; the output voltage value of the power balancer is 1 / 2 of the input voltage value, for example, when the input voltage of the power balancer is 24V, the output voltage is 12V. Generally, the output voltage value of the power balancer under no-load conditions is allowed to be about 0.4V higher than the output voltage under working conditions, that is, the no-load output voltage is allowed to be adjusted up to 12.4V. Taking this as an example, the following description Figure 2 In (a), the resistance value of resistor R5 can be calculated according to the resistance voltage division method, using the following formula (1):

[0033]

[0034] In formula (1), R1 and R2 represent the resistance of the sampling resistor in the output voltage feedback loop, and R5 represents Figure 2 In (a), Uin represents the resistance of the output voltage floating circuit resistor, and Uo represents the output voltage of the power balancer.

[0035] According to formula (1), the resistance value of R5 can be calculated by operation. The resistance value of resistor R5 is calculated by the following formula 2:

[0036]

[0037] Therefore, by selecting the resistance value of R5 according to the above formula (2), it can be ensured that the output voltage floating charging circuit composed of resistors can provide the output capacitor C1 with an output voltage slightly higher than the steady-state output voltage.

[0038] In one embodiment, Figure 2 As shown in (b), the output voltage floating charging circuit includes a resistor R6, a resistor R7, a resistor R8, a diode D1 and a transistor Q1;

[0039] The resistor R6, the diode D1 and the resistor R7 are connected in series in sequence, and the end of the resistor R7 away from the diode D1 is grounded; the end of the resistor R6 away from the diode D1 is connected to the input voltage end of the BUCK topology circuit; a first node is set on the connection line between the resistor R6 and the diode D1, a first branch is drawn from the first node and connected to the base of the transistor Q1, a second node is set on the connection line between the resistor R6 and the input voltage end of the BUCK topology circuit, a second branch is drawn from the second node and connected to the resistor R8 and the collector of the transistor Q1 in sequence; the emitter of the transistor Q1 is connected to the output voltage end of the BUCK topology circuit; the resistor R6 and the resistor R7 have the same resistance value, which is 10K to 100K.

[0040] Specifically, the output voltage floating charging circuit is implemented by an emitter-follower circuit. Resistors R7 and R8 are connected in series to divide the input voltage value. When the resistors R7 and R8 are set to the same resistance value, the voltage division value is 1 / 2 of the input voltage. When the diode D1 is connected in series between the resistors R7 and R8, the voltage at point A will be raised by 0.7V. After the transistor Q1 is normally turned on, the voltage drop between the A and B levels is about 0.3V. Since the voltage at point A has been raised by 0.7V, minus the voltage drop between the A and B levels, it is equivalent to the voltage at point B of the transistor Q1 being about 0.4V higher than 1 / 2 of the input voltage value, that is, the output voltage floating charging circuit has raised the output voltage by 0.4V under no-load conditions. After the output voltage feedback loop collects this output voltage value, the BUCK control circuit is turned off to achieve the design requirement of low power consumption under no-load conditions.

[0041] In one embodiment, the output voltage floating charging circuit includes a resistor R9, a resistor R10, a resistor R11, a voltage regulator ZD1 and a transistor Q2;

[0042] The resistor R9, the voltage regulator ZD1 and the resistor R10 are connected in series in sequence, and one end of the resistor R10 away from the voltage regulator ZD1 is grounded; one end of the resistor R9 away from the voltage regulator ZD1 is connected to the input voltage end of the BUCK topology circuit; a third node is set on the connection line between the resistor R9 and the voltage regulator ZD1, a third branch is drawn from the third node and connected to the base of the transistor Q2, a fourth node is set on the connection line between the resistor R9 and the input voltage end of the BUCK topology circuit, a fourth branch is drawn from the fourth node and connected to the resistor R11 and the collector of the transistor Q2 in sequence; the emitter of the transistor Q2 is connected to the output voltage end of the BUCK topology circuit; the resistor R9 and the resistor R10 have the same resistance value, which is 10K~100K.

[0043] Specifically, the output voltage floating charging circuit is implemented by an emitter-follower circuit, including resistors R9, R10 and R11, a voltage regulator ZD1 and a transistor Q2; resistors R9 and R10 are connected in series to divide the input voltage value, and the resistors R1 and R2 are set to have the same resistance value, so the voltage division value is 1 / 2 of the input voltage. When the voltage regulator ZD1 is connected in series between the resistors R1 and R2, the voltage at point A will be raised; assuming that the voltage regulator value of the voltage regulator ZD1 is 0.7V, the voltage drop between the A and B levels after the transistor Q1 is normally turned on is about 0.3V. Since the voltage at point A has been raised by 0.7V, minus the voltage drop between the A and B levels, it is equivalent to the voltage at point B of the transistor Q1 being about 0.4V higher than 1 / 2 of the input voltage value, that is, the output voltage floating charging circuit has raised the output voltage by 0.4V under no-load conditions, and the output voltage feedback loop collects this output voltage value and closes the BUCK control circuit to achieve the design requirement of low power consumption under no-load conditions;

[0044] In an exemplary embodiment of the present utility model, the present utility model embodiment includes at least the following advantages:

[0045] 1. The circuit design is simple and the layout takes up little space;

[0046] 2. The electronic components are universal models with low cost;

[0047] 3. Use discrete devices to facilitate debugging and maintenance.

[0048] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0049] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A low-power circuit for a BUCK topology under no-load conditions, comprising a BUCK topology circuit and a BUCK control circuit, wherein the BUCK topology circuit comprises a BUCK power circuit and an output capacitor C1; the BUCK control circuit is connected to the BUCK topology circuit; the output end of the BUCK topology circuit is an output voltage end; an input end of the BUCK topology circuit is an input voltage end; a node is set on a connection line between the output end of the BUCK power circuit and the output voltage end of the BUCK topology circuit, a branch is led out and connected to one end of the output capacitor C1, and the other end of the output capacitor C1 is grounded; It is characterized in that The circuit further includes: an output voltage floating charging circuit and an output voltage feedback loop; the input end of the output voltage floating charging circuit is connected to the input voltage end of the BUCK topology circuit, and the output end of the output voltage floating charging circuit is connected to the output voltage end of the BUCK topology circuit; the output voltage floating charging circuit is used to provide a floating charging voltage higher than the output voltage under the steady-state working condition of the BUCK topology circuit to the output capacitor C1 under the no-load condition of the BUCK topology; The output voltage feedback loop is connected to the output end of the BUCK topology circuit, and the output end of the output voltage feedback loop is connected to the BUCK control circuit.

2. The low power consumption circuit for BUCK topology under no-load condition according to claim 1, characterized in that: The output voltage feedback loop includes an operational amplifier U1, a resistor R1, a resistor R2, a resistor R3, and a resistor R4; The resistor R1 is connected in series with the resistor R2, the resistor R3 is connected in series with the resistor R4, the end of the resistor R1 away from R2 is connected to the output voltage end of the BUCK topology circuit, the end of the resistor R2 away from the resistor R1 is connected to the end of the resistor R4 away from the resistor R3 and then grounded; the end of the resistor R3 away from the resistor R4 is the input voltage end; the same-direction input end of the operational amplifier U1 is connected to the connection line between the resistor R1 and the resistor R2, and the reverse input end of the operational amplifier U1 is connected to the connection line between the resistor R3 and the resistor R4; the output end of the operational amplifier U1 is connected to the BUCK control circuit.

3. The low power consumption circuit for BUCK topology under no-load condition according to claim 2, characterized in that: The output voltage floating charging circuit includes a resistor R5; an input end of the resistor R5 is connected to an input voltage end of the BUCK topology circuit, and an output end of the resistor R5 is connected to an output voltage end of the BUCK topology circuit.

4. The low power consumption circuit for BUCK topology under no-load condition according to claim 2, characterized in that: The output voltage floating charging circuit includes a resistor R6, a resistor R7, a resistor R8, a diode D1 and a transistor Q1; The resistor R6, the diode D1 and the resistor R7 are connected in series in sequence, and the end of the resistor R7 away from the diode D1 is grounded; the end of the resistor R6 away from the diode D1 is connected to the input voltage end of the BUCK topology circuit; a first node is set on the connection line between the resistor R6 and the diode D1, a first branch is drawn from the first node and connected to the base of the transistor Q1, a second node is set on the connection line between the resistor R6 and the input voltage end of the BUCK topology circuit, a second branch is drawn from the second node and connected to the resistor R8 and the collector of the transistor Q1 in sequence; the emitter of the transistor Q1 is connected to the output voltage end of the BUCK topology circuit; the resistor R6 and the resistor R7 have the same resistance value, which is 10K to 100K.

5. The low power consumption circuit for BUCK topology under no-load condition according to claim 2, characterized in that: The output voltage floating charging circuit includes a resistor R9, a resistor R10, a resistor R11, a voltage regulator ZD1 and a transistor Q2; The resistor R9, the voltage regulator ZD1 and the resistor R10 are connected in series in sequence, and one end of the resistor R10 away from the voltage regulator ZD1 is grounded; one end of the resistor R9 away from the voltage regulator ZD1 is connected to the input voltage end of the BUCK topology circuit; a third node is set on the connection line between the resistor R9 and the voltage regulator ZD1, a third branch is drawn from the third node and connected to the base of the transistor Q2, a fourth node is set on the connection line between the resistor R9 and the input voltage end of the BUCK topology circuit, a fourth branch is drawn from the fourth node and connected to the resistor R11 and the collector of the transistor Q2 in sequence; the emitter of the transistor Q2 is connected to the output voltage end of the BUCK topology circuit; the resistor R9 and the resistor R10 have the same resistance value, which is 10K to 100K.

6. The low power consumption circuit for BUCK topology under no-load condition according to claim 3, characterized in that: The resistance of the resistor R5 is: Among them, R1 and R2 are the resistance values ​​of the sampling resistors R1 and R2 in the output voltage feedback loop, Uin is the input voltage value of the BUCK topology circuit, and Uo is the output voltage of the BUCK topology circuit.

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