Battery charger and control circuit thereof
By setting up parallel branches of the auxiliary switch circuit and the main switch circuit in the control circuit of the battery charger, switching the two to reduce the inrush current, the problem of large inrush current in the existing technology is solved, and charging is achieved protection of the appliance and battery.
Patent Information
- Application Number
- CN202411334452.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-24
- Publication Date
- 2025-02-14
AI Technical Summary
In the control circuit of existing battery chargers, the inrush current is relatively large, which can easily damage the charger and battery.
Design a control circuit for a battery charger, by setting a switch circuit module between the output end of the power conversion module and the battery connection end, the module consists of an auxiliary switch circuit and a main switch circuit, and switches the auxiliary switch circuit and the main switch by rotating the circuit to reduce inrush current.
Effectively reduces the charging surge current and avoids damage to the charger and battery.
Smart Images
Figure CN119448515A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of battery charging, and in particular to a battery charger and a control circuit thereof. Background Art
[0002] At present, the output end of the battery charger is usually equipped with a switch circuit. When the battery needs to be charged, after the charger is connected to the battery, the switch circuit is controlled to conduct to achieve charging of the battery. The main purpose is to avoid sparking when the AC power is directly connected to the battery to prevent damage to the charger or battery.
[0003] However, the following problem still exists: after the charger is connected to the battery, the control switch circuit is turned on to charge the battery. If there is a voltage difference between the voltage of the charger before the switch circuit and the battery voltage, a surge current will be generated at the moment of conduction. The greater the voltage difference, the greater the surge current will be. There is still a risk of damage to the battery or charger. Summary of the invention
[0004] The embodiment of the present invention provides a battery charger and a control circuit thereof to solve the problem that the charger and the battery are easily damaged due to large surge current in the control circuit of the existing battery charger.
[0005] To achieve the above objectives, in one embodiment, the present invention provides a control circuit of a battery charger, the control circuit of the battery charger comprising: A power conversion module (10), a control circuit module (40) and a switch circuit module, wherein the output end of the power conversion module (10) is connected to the input end of the switch circuit module, and the output end of the switch circuit module is a battery positive electrode connection end; The switch circuit module comprises a main switch circuit (30), an auxiliary switch circuit (20), and a current limiting resistor (R36); the input end of the main switch circuit (30) is connected to the output end of the power conversion module (10); the output end of the main switch circuit (30) is used to connect to the positive electrode connection end of the battery; the driving end of the main switch circuit (30) is connected to the first output end of the control circuit module (40); the input end of the auxiliary switch circuit (20) is connected to the output end of the power conversion module (10); the output end of the auxiliary switch circuit (20) is connected to one end of the current limiting resistor (R36); the other end of the current limiting resistor (R36) is connected to the output end of the main switch circuit (30); and the driving end of the auxiliary switch circuit (20) is connected to the second output end of the control circuit module (40); The control circuit module (40) is used to first control the auxiliary switch circuit (20) to be turned on, and then control the main switch circuit (30) to be turned on and the auxiliary switch circuit (20) to be turned off, so as to reduce the charging surge current.
[0006] In one embodiment, the auxiliary switch circuit (20) comprises: A first switch tube (Q1), a second switch tube (Q2) and a third switch tube (Q5), wherein the input end of the first switch tube (Q1) is connected to the output end of the power conversion module (10), the output end of the first switch tube (Q1) is connected to the input end of the second switch tube (Q2), and the output end of the second switch tube (Q2) is connected to the current limiting resistor (R36); the control end of the first switch tube (Q1) and the control end of the second switch tube (Q2) are respectively used to connect to the input end of the third switch tube (Q5), the output end of the third switch tube (Q5) is connected to the ground, and the control end of the third switch tube (Q5) is used to connect to the first output end of the control circuit module (40).
[0007] In one embodiment, the auxiliary switch circuit (20) further includes: A first resistor (R1), a first voltage stabilizing diode (ZD1), a second resistor (R35), and a third resistor (R37), wherein one end of the first resistor (R1) is connected to the output end of the first switch tube (Q1), and the other end of the first resistor (R1) is connected to the control end of the first switch tube (Q1); the first voltage stabilizing diode (ZD1) is connected in parallel with the first resistor (R1), one end of the second resistor (R35) is connected to the control end of the first switch tube (Q1), and the other end of the second resistor (R35) is connected to the input end of the third switch tube (Q5); one end of the third resistor (R37) is connected to the control end of the third switch tube (Q5), and the other end of the third resistor (R37) serves as a driving end of the auxiliary switch circuit (20).
[0008] In one embodiment, the main switch circuit (30) comprises: a fourth switch tube (Q6), a fifth switch tube (Q7) and a sixth switch tube (Q8), wherein the input end of the fourth switch tube (Q6) is connected to the output end of the power conversion module (10), the output end of the fourth switch tube (Q6) is connected to the input end of the fifth switch tube (Q7), and the output end of the fifth switch tube (Q7) is used to connect to the positive electrode connection end of the battery; the control end of the fourth switch tube (Q6) and the control end of the fifth switch tube (Q7) are respectively used to connect to the input end of the sixth switch tube (Q8), the output end of the sixth switch tube (Q8) is connected to the ground, and the control end of the sixth switch tube (Q8) is used to connect to the second output end of the control circuit module (40).
[0009] In one embodiment, the main switch circuit (30) further includes: A fourth resistor (R38), a second voltage stabilizing diode (ZD2), a fifth resistor (R39), and a sixth resistor (R40), wherein one end of the fourth resistor (R38) is connected to the output end of the fourth switch tube (Q6), and the other end of the fourth resistor (R38) is connected to the control end of the fourth switch tube (Q6); the second voltage stabilizing diode (ZD2) is connected in parallel with the fourth resistor (R38), one end of the fifth resistor (R39) is connected to the control end of the fourth switch tube (Q6), and the other end of the fifth resistor (R39) is connected to the input end of the sixth switch tube (Q8); one end of the sixth resistor (R40) is connected to the control end of the sixth switch tube (Q8), and the other end of the sixth resistor (R40) serves as the driving end of the main switch circuit (30).
[0010] In one embodiment, the control circuit of the battery charger further includes: An output voltage control circuit (50) and an output voltage sampling circuit (60), wherein a first input end of the output voltage control circuit (50) is connected to a reference voltage output end of the control circuit module (40), a second input end of the output voltage control circuit (50) is connected to an output end of the output voltage sampling circuit (60), and an input end of the output voltage sampling circuit (60) is connected to a positive output end of the power conversion module (10); and an output end of the output voltage control circuit (50) is used to output a voltage control signal.
[0011] In one embodiment, the control circuit of the battery charger further includes: An output current control circuit (70) and an output current sampling circuit (80), wherein a first input end of the output current control circuit (70) is connected to a reference current output end of the control circuit module (40), a second input end of the output current control circuit (70) is connected to an output end of the output current sampling circuit (80), and an input end of the output current sampling circuit (80) is connected to a negative output end of the power conversion module (10); and an output end of the output current control circuit (70) is used to output a current control signal.
[0012] In one embodiment, the control circuit of the battery charger further includes: An isolated feedback circuit (90), wherein a first input end of the isolated feedback circuit (90) is connected to an output end of the output voltage control circuit (50), a second input end of the isolated feedback circuit is connected to an output end of the output current control circuit (70), and an output end of the isolated feedback circuit is connected to an input end of a switch power supply control chip (13) in the power conversion module (10).
[0013] In one embodiment, the power conversion module (10) comprises: A rectifier circuit (11), a DC conversion circuit (12) and a switch power control chip (13), wherein the input end of the rectifier circuit (11) is used to input a power signal, the output end of the rectifier circuit (11) is connected to the input end of the DC conversion circuit (12), and the output end of the DC conversion circuit (12) is connected to the input end of the switch circuit module; the output end of the switch power control chip (13) is connected to a seventh switch tube (Q3) in the DC conversion circuit (12), and the switch power control chip (13) is used to output a control signal to the control end of the seventh switch tube (Q3) according to a feedback signal output by the feedback circuit.
[0014] In one embodiment, a battery charger is provided, including a charger housing, wherein a control circuit board is disposed in the charger housing, and a circuit layer of the control circuit board includes the control circuit of the battery charger described in any of the above embodiments.
[0015] The battery charger and control circuit thereof of the present invention: a switch circuit module is provided between the output end of a power conversion module (10) and the battery connection end, the switch circuit module being composed of two parallel branches, one of which is a series branch between an auxiliary switch circuit (20) and a current limiting resistor, and the other is a branch where a main switch circuit (30) is located. By switching the auxiliary switch circuit (20) and the main switch circuit (30) alternately, the surge current in the control circuit is effectively reduced, thereby avoiding the problem of large surge current in the control circuit causing easy damage to the charger and the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.
[0017] Figure 1 is a schematic diagram of a control circuit of a first battery charger in one embodiment of the present invention; Figure 2 is a schematic diagram of a control circuit of a second battery charger in one embodiment of the present invention; Figure 3 is a schematic diagram of a control circuit of a third battery charger according to an embodiment of the present invention; Figure 4 It is a schematic diagram of an output voltage / current control circuit, an output voltage / current sampling circuit, and an isolation feedback circuit in one embodiment of the present invention; Figure 5It is a circuit diagram of a rectifier circuit, a DC conversion circuit and a switch power supply control chip in one embodiment of the present invention; Explanation of reference numerals: 10, power conversion module; 20, auxiliary switch circuit; 30, main switch circuit; 40, control circuit module; 50, output voltage control circuit; 60, output voltage sampling circuit; 70, output current control circuit; 80, output current sampling circuit; 90, isolation feedback circuit. DETAILED DESCRIPTION
[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0019] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.
[0020] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.
[0021] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.
[0022] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.
[0023] In order to fully understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.
[0024] In one embodiment, if Figure 1 and Figure 2 As shown, the present invention provides a control circuit of a battery charger, the control circuit of the battery charger comprising: A power conversion module (10), a control circuit module (40) and a switch circuit module, wherein the output end of the power conversion module (10) is connected to the input end of the switch circuit module, and the output end of the switch circuit module is a battery positive electrode connection end; The switch circuit module comprises a main switch circuit (30), an auxiliary switch circuit (20), and a current limiting resistor (R36); the input end of the main switch circuit (30) is connected to the output end of the power conversion module (10); the output end of the main switch circuit (30) is used to connect to the positive electrode connection end of the battery; the driving end of the main switch circuit (30) is connected to the first output end of the control circuit module (40); the input end of the auxiliary switch circuit (20) is connected to the output end of the power conversion module (10); the output end of the auxiliary switch circuit (20) is connected to one end of the current limiting resistor (R36); the other end of the current limiting resistor (R36) is connected to the output end of the main switch circuit (30); and the driving end of the auxiliary switch circuit (20) is connected to the second output end of the control circuit module (40); The control circuit module (40) is used to first control the auxiliary switch circuit (20) to be turned on, and then control the main switch circuit (30) to be turned on and the auxiliary switch circuit (20) to be turned off, so as to reduce the charging surge current.
[0025] The working principle of the above control circuit is as follows: An original power signal is input to the input end of the power conversion module (10), the signal undergoes voltage conversion via the power conversion module (10), and the converted power signal is output from the output end of the power conversion module (10); then the control circuit module (40) sends a conduction signal to the auxiliary switch circuit (20) to control the auxiliary switch circuit (20) to be turned on; since the auxiliary switch circuit (20) is connected in series with a current limiting resistor, the surge current can be reduced by the current limiting resistor.
[0026] When the surge current is reduced, the control circuit module (40) sends a shutoff signal to the auxiliary switch circuit (20) to control the auxiliary switch circuit (20) to shut down; and the control circuit module (40) sends a conduction signal to the main switch circuit (30) to control the main switch circuit (30) to conduct, so that the converted power signal provides power supply to the subsequent load through the main switch circuit (30).
[0027] The control circuit of the battery charger of the present embodiment is provided with a switch circuit module between the output end of the power conversion module (10) and the battery connection end. The switch circuit module is composed of two parallel branches, one of which is a series branch between the auxiliary switch circuit (20) and the current limiting resistor, and the other is a branch where the main switch circuit (30) is located. By switching the auxiliary switch circuit (20) and the main switch circuit (30) alternately, the surge current in the control circuit is effectively reduced, thereby avoiding the problem that the charger and the battery are easily damaged due to the large surge current in the control circuit.
[0028] In one embodiment, if Figure 2As shown, the auxiliary switch circuit (20) comprises: A first switch tube (Q1), a second switch tube (Q2) and a third switch tube (Q5), wherein the input end of the first switch tube (Q1) is connected to the output end of the power conversion module (10), the output end of the first switch tube (Q1) is connected to the input end of the second switch tube (Q2), and the output end of the second switch tube (Q2) is connected to the current limiting resistor (R36); the control end of the first switch tube (Q1) and the control end of the second switch tube (Q2) are respectively used to connect to the input end of the third switch tube (Q5), the output end of the third switch tube (Q5) is connected to the ground, and the control end of the third switch tube (Q5) is used to connect to the first output end of the control circuit module (40).
[0029] The working principle of the auxiliary switch circuit (20) is as follows: The control circuit module (40) sends a turn-on signal to the third switch tube (Q5) of the auxiliary switch circuit (20). After the third switch tube (Q5) is turned on, its input end and output end are turned on, which is equivalent to the control ends of the first switch tube (Q1) and the second switch tube (Q2) being grounded, thereby controlling the P-type first switch tube (Q1) and the second switch tube (Q2) to also be turned on, so that the auxiliary switch circuit (20) is turned on.
[0030] In the control circuit of this embodiment, the auxiliary switch circuit (20) is formed by three switch tubes. Since the auxiliary switch circuit (20) is connected in series with a current limiting resistor (R36), the surge current can be reduced by the current limiting resistor (R36).
[0031] In one embodiment, if Figure 2 As shown, the auxiliary switch circuit (20) further includes: A first resistor (R1), a first voltage stabilizing diode (ZD1), a second resistor (R35), and a third resistor (R37), wherein one end of the first resistor (R1) is connected to the output end of the first switch tube (Q1), and the other end of the first resistor (R1) is connected to the control end of the first switch tube (Q1); the first voltage stabilizing diode (ZD1) is connected in parallel with the first resistor (R1), one end of the second resistor (R35) is connected to the control end of the first switch tube (Q1), and the other end of the second resistor (R35) is connected to the input end of the third switch tube (Q5); one end of the third resistor (R37) is connected to the control end of the third switch tube (Q5), and the other end of the third resistor (R37) serves as a driving end of the auxiliary switch circuit (20).
[0032] The control circuit module (40) sends a conduction signal to the third switch tube (Q5) of the auxiliary switch circuit (20) through the third resistor (R37), and the third resistor (R37) plays a current limiting role in controlling the conduction signal; after the third switch tube (Q5) is turned on, its input end and output end are turned on, which is equivalent to the control end of the first switch tube (Q1) and the second switch tube (Q2) being grounded, thereby controlling the P-type first switch tube (Q1) and the second switch tube (Q2) to also be turned on, and the first switch tube (Q1) and the second switch tube (Q2) then play a voltage stabilizing role through the first resistor (R1), the first voltage stabilizing diode (ZD1) and the second resistor (R35).
[0033] In one embodiment, if Figure 2 As shown, the main switch circuit (30) comprises: a fourth switch tube (Q6), a fifth switch tube (Q7) and a sixth switch tube (Q8), wherein the input end of the fourth switch tube (Q6) is connected to the output end of the power conversion module (10), the output end of the fourth switch tube (Q6) is connected to the input end of the fifth switch tube (Q7), and the output end of the fifth switch tube (Q7) is used to connect to the positive electrode connection end of the battery; the control end of the fourth switch tube (Q6) and the control end of the fifth switch tube (Q7) are respectively used to connect to the input end of the sixth switch tube (Q8), the output end of the sixth switch tube (Q8) is connected to the ground, and the control end of the sixth switch tube (Q8) is used to connect to the second output end of the control circuit module (40).
[0034] The working principle of the main switch circuit (30) is as follows: The control circuit module (40) sends a turn-on signal to the sixth switch tube (Q8). After the sixth switch tube (Q8) is turned on, its input end and output end are turned on, which is equivalent to the control ends of the fourth switch tube (Q6) and the fifth switch tube (Q7) being grounded, thereby controlling the P-type fourth switch tube (Q6) and the fifth switch tube (Q7) to also be turned on, so that the main switch circuit (30) is turned on, so that the converted power signal provides power supply to the subsequent load through the main switch circuit (30).
[0035] In one embodiment, if Figure 2 As shown, the main switch circuit (30) further includes: A fourth resistor (R38), a second voltage stabilizing diode (ZD2), a fifth resistor (R39), and a sixth resistor (R40), wherein one end of the fourth resistor (R38) is connected to the output end of the fourth switch tube (Q6), and the other end of the fourth resistor (R38) is connected to the control end of the fourth switch tube (Q6); the second voltage stabilizing diode (ZD2) is connected in parallel with the fourth resistor (R38), one end of the fifth resistor (R39) is connected to the control end of the fourth switch tube (Q6), and the other end of the fifth resistor (R39) is connected to the input end of the sixth switch tube (Q8); one end of the sixth resistor (R40) is connected to the control end of the sixth switch tube (Q8), and the other end of the sixth resistor (R40) serves as the driving end of the main switch circuit (30).
[0036] The control circuit module (40) sends a conduction signal to the sixth switch tube (Q8) of the main switch circuit (30) through the sixth resistor (R40), and the sixth resistor (R40) plays a current limiting role in controlling the conduction signal; after the sixth switch tube (Q8) is turned on, its input end and output end are turned on, which is equivalent to the control end of the fourth switch tube (Q6) and the fifth switch tube (Q7) being grounded, thereby controlling the P-type fourth switch tube (Q6) and the fifth switch tube (Q7) to also be turned on, and after the fourth switch tube (Q6) and the fifth switch tube (Q7) are turned on, they play a voltage stabilizing role through the fourth resistor (R38), the second voltage stabilizing diode (ZD2) and the fifth resistor (R39).
[0037] In one embodiment, if Figure 3 As shown, the control circuit of the battery charger also includes: An output voltage control circuit (50) and an output voltage sampling circuit (60), wherein a first input end of the output voltage control circuit (50) is connected to a reference voltage output end of the control circuit module (40), a second input end of the output voltage control circuit (50) is connected to an output end of the output voltage sampling circuit (60), and an input end of the output voltage sampling circuit (60) is connected to a positive output end of the power conversion module (10); and an output end of the output voltage control circuit (50) is used to output a voltage control signal.
[0038] like Figure 4As shown, the output voltage control circuit (50) includes a comparator (U4B), the inverting input terminal of the comparator (U4B) is connected to a first voltage divider circuit composed of a seventh resistor (R23) and an eighth resistor (R22), the voltage dividing point of the seventh resistor (R23) and the eighth resistor (R22) is connected to a reference voltage output terminal Output Voltage Control of the control circuit module (40) through a ninth resistor (R8) and a tenth resistor (R24), and the output voltage sampling circuit (60) includes an eleventh resistor (R27) and a twelfth resistor (R28) connected in series, and the eleventh resistor (R27) is connected to the non-inverting input terminal of the comparator (U4B).
[0039] Among them, the working principle of the above control circuit is: When the power conversion module (10) supplies power to the battery via the main switch circuit (30), the output voltage sampling circuit (60) collects a power signal from the positive output terminal of the power conversion module (10), and sends the power signal to the output voltage control circuit (50). The output voltage control circuit (50) outputs a first control signal for controlling whether the power conversion module (10) is turned on, based on a comparison between the power signal and a reference voltage signal output from a reference voltage output terminal of the control circuit module (40), so as to achieve overvoltage control of the control circuit.
[0040] In one embodiment, if Figure 3 As shown, the control circuit of the battery charger also includes: An output current control circuit (70) and an output current sampling circuit (80), wherein a first input end of the output current control circuit (70) is connected to a reference current output end of the control circuit module (40), a second input end of the output current control circuit (70) is connected to an output end of the output current sampling circuit (80), and an input end of the output current sampling circuit (80) is connected to a negative output end of the power conversion module (10); and an output end of the output current control circuit (70) is used to output a current control signal.
[0041] like Figure 4As shown, the output current control circuit (70) includes a comparator (U4A), the inverting input terminal of the comparator (U4A) is connected to a second voltage divider circuit composed of a thirteenth resistor (R15) and a fourteenth resistor (R17), the voltage divider point of the thirteenth resistor (R15) and the fourteenth resistor (R17) is connected to the reference current output terminal Output Curent Control of the control circuit module (40) through a fifteenth resistor (R42) and a sixteenth resistor (R41), and the output voltage sampling circuit (60) includes a seventeenth resistor (R19), one end of the seventeenth resistor (R19) is connected to the negative output terminal VOUT- of the power conversion module (10), and the other end of the seventeenth resistor (R19) is connected to the non-inverting input terminal of the comparator (U4A).
[0042] Among them, the working principle of the above control circuit is: When the power conversion module (10) supplies power to the battery via the main switch circuit (30), the output current sampling circuit (80) collects a current detection signal from the negative output terminal of the power conversion module (10), and sends the current detection signal to the output current control circuit (70). The output current control circuit (70) outputs a second control signal for controlling whether the power conversion module (10) is turned on, based on a comparison between the current detection signal and a reference current signal output from a reference current output terminal of the control circuit module (40), so as to achieve overcurrent control of the control circuit.
[0043] In one embodiment, if Figure 3 As shown, the control circuit of the battery charger also includes: An isolated feedback circuit (90), wherein a first input end of the isolated feedback circuit (90) is connected to an output end of the output voltage control circuit (50), a second input end of the isolated feedback circuit is connected to an output end of the output current control circuit (70), and an output end of the isolated feedback circuit is connected to an input end of a switch power supply control chip (13) in the power conversion module (10).
[0044] like Figure 4As shown, the isolated feedback circuit (90) includes: a photoelectric coupler, a first diode (D6), an eighteenth resistor (R18), a second diode (D7), a nineteenth resistor (R26), a voltage regulator diode (ZD2) and a twentieth resistor (R14), wherein one end of the series branch of the first diode (D6) and the eighteenth resistor (R18) is connected to the output end of the comparator (U4A), and the other end is connected to the diode (U1A) input end of the photoelectric coupler; one end of the series branch of the second diode (D7) and the nineteenth resistor (R26) is connected to the output end of the comparator (U4B), and the other end is connected to the diode (U1A) input end of the photoelectric coupler; one end of the series branch of the voltage regulator diode (ZD2) and the twentieth resistor (R14) is connected to the positive output end of the power conversion module (10), and the other end is connected to the diode (U1A) input end of the photoelectric coupler; and the output end of the photoelectric coupler is connected to the switch power control chip (13).
[0045] Among them, the working principle of the above control circuit is: When the power conversion module (10) supplies power to the battery via the main switch circuit (30), the output voltage control circuit (50) compares the power signal at the positive output terminal of the power conversion module (10) with the reference voltage signal. When the power signal is greater than the reference voltage signal (preset maximum power supply voltage), the output voltage control circuit (50) outputs a first control signal to the isolation feedback circuit (90). The isolation feedback circuit (90) feeds the signal back to the switch power control chip (13) of the power conversion module (10). The switch power control chip (13) makes corresponding adjustments to stabilize the output voltage and charge the battery.
[0046] Furthermore, when the power conversion module (10) supplies power to the battery via the main switch circuit (30), the output current control circuit (70) compares the current detection signal at the negative output terminal of the power conversion module (10) with the reference current signal. When the current detection signal is greater than the reference current signal (preset maximum power supply current), the second control signal is output to the isolation feedback circuit (90). The isolation feedback circuit (90) feeds back the signal to the switch power control chip (13) of the power conversion module (10). The switch power control chip (13) makes corresponding adjustments to stabilize the output current and charge the battery.
[0047] In one embodiment, if Figure 5 As shown, the power conversion module (10) comprises: A rectifier circuit (11), a DC conversion circuit (12) and a switch power control chip (13), wherein the input end of the rectifier circuit (11) is used to input a power signal, the output end of the rectifier circuit (11) is connected to the input end of the DC conversion circuit (12), and the output end of the DC conversion circuit (12) is connected to the input end of the switch circuit module; the output end of the switch power control chip (13) is connected to a seventh switch tube (Q3) in the DC conversion circuit (12), and the switch power control chip (13) is used to output a control signal to the control end of the seventh switch tube (Q3) according to a feedback signal output by the feedback circuit.
[0048] The rectifier circuit (11) may be a flyback AC-DC, a forward AC-DC, a push-pull AC-DC, a half-bridge AC-DC, or a full-bridge AC-DC, and the DC conversion circuit (12) may be a boost DC-DC, a buck DC-DC, or a buck-boost DC-DC.
[0049] In the above power conversion module (10), the feedback signal output by the feedback circuit is the first control signal or the second control signal mentioned in the above embodiment.
[0050] In conjunction with the control circuit of the battery charger shown in FIG3, FIG4, and FIG5, the control method thereof includes: A charging current signal Imin with a relatively small output is provided to the control circuit module (40) through the main controller MCU, and the control circuit controls the auxiliary switch circuit (20) to be turned on, and a current limiting resistor connected in series with the auxiliary switch circuit (20) is used to reduce the surge current. At this time, the charging current Imin is the reference current provided by the main controller MCU to the control circuit module (40), and then the isolated feedback circuit (90) feeds back the feedback signal to the primary side power control chip in the power conversion module (10) to adjust the output current, thereby determining the magnitude of the output current.
[0051] When the auxiliary switch circuit (20) is turned on, the calculation formula of the output voltage of the switching power supply is as follows: Vout= Vbat+Imin*(R1+Rs2)≈Vbat+Imin*R1 Wherein, Vout is the output voltage of the switching power supply, that is, the output voltage of the power conversion module (10); Vbat is the battery voltage, Imin is the charging current, R1 is the resistance value of the current limiting resistor, and Rs2 is the equivalent impedance of the auxiliary switch in the auxiliary switch circuit (20). Since the charging current Imin is relatively small, the voltage difference between the output voltage Vout of the switching power supply and the battery voltage is also relatively small. At this time, the main switch circuit (30) is controlled to be turned on, and the surge current formed in this way will also be very small. The calculation formula of the surge current is as follows: I=(Vout-Vbat) / Rs1=Imin*R1 / Rs1 Wherein, I is the surge current, Vout is the output voltage of the switching power supply, Vbat is the battery voltage, R1 is the resistance value of the current limiting resistor, and Rs1 is the switch equivalent impedance in the main switching circuit (30).
[0052] The output current can be adjusted according to actual needs later. For example, when the surge current at the moment of charging is reduced, the MCU can steadily increase the reference current to the current control loop, so that the power IC controls the output end to gradually and steadily increase the output current, thereby speeding up the battery charging speed.
[0053] In one embodiment, a battery charger is provided, including a charger housing, wherein a control circuit board is disposed in the charger housing, and a circuit layer of the control circuit board includes the control circuit of the battery charger described in any of the above embodiments.
[0054] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.
Claims
1. A control circuit for a battery charger, characterized in that: The control circuit of the battery charger comprises: A power conversion module (10), a control circuit module (40) and a switch circuit module, wherein the output end of the power conversion module (10) is connected to the input end of the switch circuit module, and the output end of the switch circuit module is a battery positive electrode connection end; The switch circuit module comprises a main switch circuit (30), an auxiliary switch circuit (20), and a current limiting resistor (R36); the input end of the main switch circuit (30) is connected to the output end of the power conversion module (10); the output end of the main switch circuit (30) is used to connect to the positive electrode connection end of the battery; the driving end of the main switch circuit (30) is connected to the first output end of the control circuit module (40); the input end of the auxiliary switch circuit (20) is connected to the output end of the power conversion module (10); the output end of the auxiliary switch circuit (20) is connected to one end of the current limiting resistor (R36); the other end of the current limiting resistor (R36) is connected to the output end of the main switch circuit (30); and the driving end of the auxiliary switch circuit (20) is connected to the second output end of the control circuit module (40); The control circuit module (40) is used to first control the auxiliary switch circuit (20) to be turned on, and then control the main switch circuit (30) to be turned on and the auxiliary switch circuit (20) to be turned off, so as to reduce the charging surge current.
2. The control circuit of the battery charger according to claim 1, characterized in that: The auxiliary switch circuit (20) comprises: A first switch tube (Q1), a second switch tube (Q2) and a third switch tube (Q5), wherein the input end of the first switch tube (Q1) is connected to the output end of the power conversion module (10), the output end of the first switch tube (Q1) is connected to the input end of the second switch tube (Q2), and the output end of the second switch tube (Q2) is connected to the current limiting resistor (R36); the control end of the first switch tube (Q1) and the control end of the second switch tube (Q2) are respectively used to connect to the input end of the third switch tube (Q5), the output end of the third switch tube (Q5) is connected to the ground, and the control end of the third switch tube (Q5) is used to connect to the first output end of the control circuit module (40).
3. The control circuit of the battery charger according to claim 2, characterized in that: The auxiliary switch circuit (20) further includes: A first resistor (R1), a first voltage stabilizing diode (ZD1), a second resistor (R35), and a third resistor (R37), wherein one end of the first resistor (R1) is connected to the output end of the first switch tube (Q1), and the other end of the first resistor (R1) is connected to the control end of the first switch tube (Q1); the first voltage stabilizing diode (ZD1) is connected in parallel with the first resistor (R1), one end of the second resistor (R35) is connected to the control end of the first switch tube (Q1), and the other end of the second resistor (R35) is connected to the input end of the third switch tube (Q5); one end of the third resistor (R37) is connected to the control end of the third switch tube (Q5), and the other end of the third resistor (R37) serves as a driving end of the auxiliary switch circuit (20).
4. The control circuit of the battery charger according to claim 1, characterized in that: The main switch circuit (30) comprises: a fourth switch tube (Q6), a fifth switch tube (Q7) and a sixth switch tube (Q8), wherein the input end of the fourth switch tube (Q6) is connected to the output end of the power conversion module (10), the output end of the fourth switch tube (Q6) is connected to the input end of the fifth switch tube (Q7), and the output end of the fifth switch tube (Q7) is used to connect to the positive electrode connection end of the battery; the control end of the fourth switch tube (Q6) and the control end of the fifth switch tube (Q7) are respectively used to connect to the input end of the sixth switch tube (Q8), the output end of the sixth switch tube (Q8) is connected to the ground, and the control end of the sixth switch tube (Q8) is used to connect to the second output end of the control circuit module (40).
5. The control circuit of the battery charger according to claim 4, characterized in that: The main switch circuit (30) further includes: A fourth resistor (R38), a second voltage stabilizing diode (ZD2), a fifth resistor (R39), and a sixth resistor (R40), wherein one end of the fourth resistor (R38) is connected to the output end of the fourth switch tube (Q6), and the other end of the fourth resistor (R38) is connected to the control end of the fourth switch tube (Q6); the second voltage stabilizing diode (ZD2) is connected in parallel with the fourth resistor (R38), one end of the fifth resistor (R39) is connected to the control end of the fourth switch tube (Q6), and the other end of the fifth resistor (R39) is connected to the input end of the sixth switch tube (Q8); one end of the sixth resistor (R40) is connected to the control end of the sixth switch tube (Q8), and the other end of the sixth resistor (R40) serves as the driving end of the main switch circuit (30).
6. The control circuit of the battery charger according to claim 1, characterized in that: The control circuit of the battery charger also includes: An output voltage control circuit (50) and an output voltage sampling circuit (60), wherein a first input end of the output voltage control circuit (50) is connected to a reference voltage output end of the control circuit module (40), a second input end of the output voltage control circuit (50) is connected to an output end of the output voltage sampling circuit (60), and an input end of the output voltage sampling circuit (60) is connected to a positive output end of the power conversion module (10); and an output end of the output voltage control circuit (50) is used to output a voltage control signal.
7. The control circuit of the battery charger according to claim 6, characterized in that: The control circuit of the battery charger also includes: An output current control circuit (70) and an output current sampling circuit (80), wherein a first input end of the output current control circuit (70) is connected to a reference current output end of the control circuit module (40), a second input end of the output current control circuit (70) is connected to an output end of the output current sampling circuit (80), and an input end of the output current sampling circuit (80) is connected to a negative output end of the power conversion module (10); and an output end of the output current control circuit (70) is used to output a current control signal.
8. The control circuit of the battery charger according to claim 7, characterized in that: The control circuit of the battery charger also includes: An isolated feedback circuit (90), wherein a first input end of the isolated feedback circuit (90) is connected to an output end of the output voltage control circuit (50), a second input end of the isolated feedback circuit is connected to an output end of the output current control circuit (70), and an output end of the isolated feedback circuit is connected to an input end of a switch power supply control chip (13) in the power conversion module (10).
9. The control circuit of the battery charger according to claim 8, characterized in that: The power conversion module (10) comprises: A rectifier circuit (11), a DC conversion circuit (12) and a switch power control chip (13), wherein the input end of the rectifier circuit (11) is used to input a power signal, the output end of the rectifier circuit (11) is connected to the input end of the DC conversion circuit (12), and the output end of the DC conversion circuit (12) is connected to the input end of the switch circuit module; the output end of the switch power control chip (13) is connected to a seventh switch tube (Q3) in the DC conversion circuit (12), and the switch power control chip (13) is used to output a control signal to the control end of the seventh switch tube (Q3) according to a feedback signal output by the feedback circuit.
10. A battery charger, comprising a charger housing, characterized in that: A control circuit board is arranged in the charger housing, and a circuit layer of the control circuit board includes the control circuit of the battery charger according to any one of claims 1 to 9.