A charging control circuit

Abstract

The present invention discloses a charging control circuit, which is suitable for a charger, including: a photoelectric coupling module, an input end connected to a detection module and a control module, an output end connected to the voltage end of the charger, and a control end connected to the primary control chip of the charger, which is used to control the actual charging voltage and current of the charger according to the signal output by the detection module; the detection module is used to detect the actual charging voltage and actual charging current of the charger and output a control signal; the control module is used to limit the actual charging voltage of the charger within a safe charging voltage range according to the control signal output by the detection module. The beneficial effect of the technical solution of the present invention is that when the MCU or the detection circuit fails, the charging control circuit can still adjust the actual charging voltage and limit the actual charging voltage to within a preset safe charging voltage range to prevent the battery from being overheated and damaged, causing a combustion accident.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and in particular to a charging control circuit. Background Art

[0002] Compared with traditional chargers, current battery chargers organically combine high-frequency switching power supply technology with embedded microcomputer control technology, and use intelligent dynamic adjustment technology to optimize the charging characteristic curve, thereby effectively extending the service life of the battery. Battery chargers in the prior art can adopt multiple charging methods such as constant current / constant voltage / small constant current, so they have the characteristics of high reliability, simple operation, light weight, and small size.

[0003] In the prior art, chargers are generally provided with voltage and current reference signals by an embedded microcomputer (MCU) or other external sources, which are then compared with the actual output voltage / output current of the charger itself, and the charger is controlled according to the comparison results. This control method has a good control effect when the charger is working normally. However, when the current / voltage detection circuit of the charger fails or the external MCU or other equipment fails, resulting in the inability to output the detection result, the charger will lose control of the charging process, which may cause the charger to overheat and be damaged due to the actual output voltage being too high, and even cause a combustion accident. Summary of the invention

[0004] In view of the problems existing in the prior art, a charging control circuit is now provided to solve the problem that when the MCU or the detection circuit fails, the charging voltage of the charger is too high, causing the battery to overheat and be damaged, or even cause a combustion accident.

[0005] The above technical solution specifically includes:

[0006] A charging control circuit, applicable to a charger, comprising:

[0007] an optoelectronic coupling module, wherein an input end of the optoelectronic coupling module is connected to a detection module and a control module, an output end of the optoelectronic coupling module is connected to a voltage end of the charger, and a control end of the optoelectronic coupling module is connected to a primary side control chip of the charger;

[0008] The photoelectric coupling module is used to generate a feedback signal according to the first control signal output by the detection module and feed it back to the charger to control the actual charging voltage and current of the charger;

[0009] The detection module includes a voltage detection unit and a current detection unit, the output end of the voltage detection unit and the output end of the current detection unit together constitute the output end of the detection module, the input end of the voltage detection unit is used to detect the actual charging voltage of the charger, and the input end of the current detection unit is used to detect the actual charging current of the charger;

[0010] The detection module is used to output the corresponding control signal according to the actual charging voltage and the actual charging current;

[0011] a control module, wherein an input end of the control module is connected to a voltage end of the charger, an output end of the control module is connected to an input end of the photoelectric coupling module, and a ground end of the control module is grounded;

[0012] The control module is used for:

[0013] When the detection module outputs the first control signal normally, the control module is not turned on;

[0014] When the detection module cannot output the first control signal normally, the control module is turned on, and generates a corresponding second control signal according to the input signal of the input end and sends it to the photoelectric coupling module. The photoelectric coupling module generates the feedback signal according to the second control signal and feeds it back to the charger to limit the actual charging voltage of the charger within a preset safe charging voltage range.

[0015] Preferably, in the charging control circuit, the photoelectric coupling module comprises a photoelectric coupler:

[0016] The first pin of the photoelectric coupler is connected to the voltage end of the charger through a first resistor in series to form the output end of the photoelectric coupling module;

[0017] The second pin of the photoelectric coupler serves as the input end of the photoelectric coupling module;

[0018] The third pin of the photoelectric coupler is grounded;

[0019] The fourth pin of the photoelectric coupler serves as the control end of the photoelectric coupling module.

[0020] The photoelectric coupler is used to transmit the electrical signal input to the input end of the photoelectric coupling module, and plays a role in isolating the electrical signal input to the input end of the photoelectric coupling module and the electrical signal output from the output end of the photoelectric coupling module.

[0021] Preferably, in the charging control circuit, the current detection unit in the detection module includes a first operational amplifier:

[0022] The non-inverting input terminal of the first operational amplifier is connected to a current reference signal provided by an external micro control unit through a second resistor in series;

[0023] The inverting input terminal of the first operational amplifier is connected to a current detection signal provided by an external micro control unit through a third resistor in series;

[0024] The output end of the first operational amplifier is connected to the second pin of the photocoupler via a first diode in series;

[0025] The voltage input terminal of the first operational amplifier is connected to a constant external voltage;

[0026] The ground terminal of the first operational amplifier is grounded;

[0027] The first operational amplifier is used to compare the current detection signal with the current reference signal, and output a corresponding first sub-control signal according to the comparison result.

[0028] Preferably, in the charging control circuit, the current detection unit in the detection module further includes a first capacitor:

[0029] The first capacitor is connected between the inverting input terminal and the output terminal of the first operational amplifier via a fourth resistor in series.

[0030] Preferably, in the charging control circuit, the voltage detection unit in the detection module includes a second operational amplifier:

[0031] The non-inverting input terminal of the second operational amplifier is connected to a voltage reference signal provided by an external micro control unit via a fifth resistor in series;

[0032] The inverting input terminal of the second operational amplifier is connected to a first voltage-dividing sampling module, which is used to obtain a voltage detection signal after performing voltage-dividing sampling processing on the actual charging voltage input from the output terminal of the charger, and input the voltage detection signal to the inverting input terminal of the second operational amplifier;

[0033] The output end of the second operational amplifier is connected to the second pin of the photocoupler via a second diode in series;

[0034] The second operational amplifier is used to compare the voltage detection signal with the voltage reference signal, and output a corresponding second sub-control signal according to the comparison result.

[0035] Preferably, in the charging control circuit, the first voltage division sampling module comprises:

[0036] a sixth resistor connected in series between the inverting input terminal of the second operational amplifier and the output terminal of the charger;

[0037] a seventh resistor, wherein the seventh resistor is connected in series between the inverting input terminal of the second operational amplifier and a ground terminal.

[0038] Preferably, in the charging control circuit, the voltage detection unit in the detection module further includes a second capacitor:

[0039] A second capacitor is connected between the inverting input terminal and the output terminal of the second operational amplifier via an eighth resistor in series.

[0040] Preferably, in the charging control circuit, the control module includes a processing unit, and the processing unit includes:

[0041] An input end connected to a second voltage-dividing sampling module, the second voltage-dividing sampling module is used to obtain a voltage detection signal after voltage-dividing sampling processing on the actual charging voltage input from the output end of the charger, and input the voltage detection signal to the first input end of the processing unit;

[0042] An output terminal connected to the input terminal of the photoelectric coupling module;

[0043] Ground terminal, connected to the ground wire.

[0044] Preferably, the second partial pressure sampling module comprises:

[0045] a first adjustable resistor, the first adjustable resistor being connected in series between the voltage terminal of the charger and the input terminal of the processing unit;

[0046] a second adjustable resistor, the second adjustable resistor being connected in series between the input terminal of the processing unit and a ground terminal;

[0047] The first adjustable resistor and the second adjustable resistor are used to limit an upper limit value of the safe charging voltage range.

[0048] Preferably, in the charging control circuit, the control module further comprises a third capacitor:

[0049] The third capacitor is connected between the first input terminal and the output terminal of the processing unit by being connected in series with a ninth resistor.

[0050] The beneficial effect of the technical solution of the present invention is that when the MCU or the detection circuit fails, the charging control circuit can still adjust the actual charging voltage and limit the actual charging voltage to within a preset safe charging voltage range to prevent the battery from overheating and being damaged, causing a combustion accident. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The embodiments of the present invention will be described more fully with reference to the attached drawings, which are provided for illustration and description only and are not intended to limit the scope of the present invention.

[0052] Figure 1 Schematic diagram of a charging control circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] 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 only 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.

[0054] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0055] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0056] The present invention provides a safety control circuit, which is applicable to a charger and includes:

[0057] A photoelectric coupling module 1, wherein the input end of the photoelectric coupling module 1 is connected to the detection module 2 and the control module 3, the output end of the photoelectric coupling module 1 is connected to the voltage end VOUT of the charger, and the control end of the photoelectric coupling module 1 is connected to the primary side control chip of the charger;

[0058] The photoelectric coupling module 1 is used to generate a feedback signal according to the control signal A1 output by the detection module 2 and feed it back to the charger to control the actual charging voltage and current of the charger;

[0059] The detection module 2 includes a current detection unit 4 and a voltage detection unit 5. The output end of the voltage detection unit 5 and the output end of the current detection unit 4 together constitute the output end of the detection module 2. The input end of the voltage detection unit 5 is used to detect the actual charging voltage of the charger, and the input end of the current detection unit 4 is used to detect the actual charging current of the charger.

[0060] The detection module 2 is used to output a corresponding control signal A1 according to the actual charging voltage and the actual charging current;

[0061] A control module 3, wherein the input end of the control module 3 is connected to the voltage end VOUT of the charger, the output end of the control module 3 is connected to the input end of the photoelectric coupling module 1, and the ground end of the control module 3 is grounded;

[0062] The control module 3 is used to output a control signal A2 according to the actual charging voltage.

[0063] Through the safety control circuit provided above, such as Figure 1 As shown, the external microcontroller unit MCU provides the circuit with an actual charging current reference signal, an actual charging current detection signal, and an actual charging voltage reference signal;

[0064] Furthermore, when the detection module 2 normally outputs the control signal A1, the output terminal of the detection module 2 outputs a high level, the output terminal of the control module 3 is also a high level, and the control module 3 is not turned on, so the control module 3 does not work in the maximum voltage control circuit of the charger;

[0065] When a fault occurs in the circuit of the external microcontroller unit MCU or the detection module 2, the detection module 2 cannot output the control signal A1 normally, the output end of the detection module 2 outputs a low level, and the output end of the control module 3 is also a low level. At this time, the control module 3 is turned on, and the control module 3 outputs a control signal A2 according to the actual charging voltage input by the voltage end VOUT of the charger. The control signal A2 is input to the photoelectric coupling module 1, and the photoelectric coupling module 1 generates a feedback signal and feeds it back to the charger, thereby limiting the actual charging voltage of the charger to within a specified safe charging voltage range.

[0066] In a preferred embodiment, the photoelectric coupling module 1 includes a photoelectric coupler U2:

[0067] The first pin of the photocoupler U2 is connected to the voltage terminal VOUT of the charger through a series resistor R1 to form the output terminal of the photocoupler U2;

[0068] The second pin of the photoelectric coupler U2 serves as the input end of the photoelectric coupling module 1;

[0069] The third pin of the optocoupler U2 is grounded;

[0070] The fourth pin of the photoelectric coupler U2 serves as the control end of the photoelectric coupling module;

[0071] The photocoupler U2 is used to transmit the electrical signal inputted from the input end of the photoelectric coupling module 1 , and plays a role in isolating the electrical signal inputted from the input end of the photoelectric coupling module 1 and the electrical signal outputted from the control end of the photoelectric coupling module 1 .

[0072] In a preferred embodiment, the current detection unit 4 includes an operational amplifier U1A:

[0073] The non-inverting input terminal of the operational amplifier U1A is connected to the actual charging current reference signal provided by the external microcontroller unit MCU through a series resistor R7;

[0074] The inverting input terminal of the operational amplifier U1A is connected to the actual charging current detection signal provided by the external microcontroller unit MCU through a series resistor R8;

[0075] The output terminal of the operational amplifier U1A is connected to the second pin of the photocoupler U2 via a diode D1 in series;

[0076] The voltage input terminal of the operational amplifier U1A is connected to an external constant voltage Vcc;

[0077] The ground terminal of the operational amplifier U1A is connected to ground;

[0078] The operational amplifier U1A is used to compare the current detection signal with the current reference signal and output a corresponding sub-control signal A11 according to the comparison result.

[0079] In a preferred embodiment, the current detection unit 4 further includes a capacitor C2:

[0080] Capacitor C2 is connected between the inverting input terminal and the output terminal of operational amplifier U1A through series resistor R9;

[0081] Capacitor C2 is connected in series with resistor R9 to block the direct current in the current detection signal input to the reverse input terminal of the operational amplifier U1A and conduct the alternating current in the current detection signal input to the reverse input terminal of the operational amplifier U1A.

[0082] In a preferred embodiment, the voltage detection unit 5 includes an operational amplifier U1B:

[0083] The non-inverting input terminal of the operational amplifier U1B is connected to the actual charging voltage reference signal provided by the external microcontroller unit MCU through a series resistor R4;

[0084] The reverse input terminal of the operational amplifier U1B is connected to the voltage division sampling module 6; the voltage division sampling module 6 is used to obtain a voltage detection signal after voltage division sampling processing of the actual charging voltage input from the output terminal VOUT of the charger, and input the voltage detection signal to the reverse input terminal of the operational amplifier U1B;

[0085] The output terminal of the operational amplifier U1B is connected to the second pin of the photocoupler U2 via a series diode D2;

[0086] The operational amplifier U1B is used to compare the voltage detection signal with the voltage reference signal, and output a corresponding sub-control signal A12 according to the comparison result.

[0087] In a preferred embodiment, the partial pressure sampling module 6 includes:

[0088] Resistor R2, which is connected in series between the inverting input terminal of the operational amplifier U1B and the output terminal VOUT of the charger;

[0089] The resistor R3 is connected in series between the inverting input terminal of the operational amplifier U1B and a ground terminal.

[0090] In a preferred embodiment, the voltage detection unit 5 further includes a capacitor C1:

[0091] Capacitor C1 is connected between the inverting input terminal and the output terminal of the operational amplifier U1B via a series resistor R5;

[0092] The capacitor C1 is connected in series with the resistor R5 to filter the voltage detection signal inputted from the reverse input terminal of the operational amplifier U1B, so that the filtered voltage detection signal becomes stable.

[0093] In a preferred embodiment, the control module 3 includes a processing unit 7, and the processing unit 7 includes:

[0094] Pin 1 is connected to the voltage division sampling unit 8, which is used to obtain a voltage detection signal after voltage division sampling processing of the actual charging voltage input from the output end of the charger, and input the voltage detection signal to the pin 1 of the processing unit 7;

[0095] Pin 2, connected to ground;

[0096] Pin 3 is connected to the input end of the optocoupler module 1.

[0097] Specifically, the processing unit 7 is a chip U3, model TL431.

[0098] In a preferred embodiment, the partial pressure sampling unit 8 includes:

[0099] A resistor R10, the resistor R10 is connected in series between the voltage terminal VOUT of the charger and the pin 1 of the processing unit 7;

[0100] Resistor R11, the resistor R11 is connected in series between the voltage terminal VOUT of the charger and the ground terminal;

[0101] Specifically, the resistor R10 and the resistor R11 are adjustable resistors, which are used to limit the upper limit value of the safe charging voltage range.

[0102] In a preferred embodiment, the control module 3 further includes a capacitor C3:

[0103] The capacitor C3 is connected between the pin 1 and the pin 3 of the processing unit 7 by being connected in series with a resistor R12 .

[0104] The capacitor C3 is connected in series with the resistor R12 to block the direct current in the current detection signal and conduct the alternating current in the current detection signal. It also plays a role in filtering the input voltage detection signal, so that the filtered voltage detection signal becomes stable.

[0105] Furthermore, when the detection module 2 outputs the control signal normally, the output end of the operational amplifier U1A outputs a low level, the diode D1 is turned on, the output end of the operational amplifier U1B outputs a low level, the diode D2 is turned on, the output end of the detection module 2 outputs a high level, the output end of the chip U3 is also a high level, and the chip U3 is not turned on, so it does not work in the charger maximum voltage control circuit;

[0106] When a fault occurs in the circuit of the external microcontroller unit MCU or the detection module 2, the detection module 2 cannot output the control signal A1 normally, the output end of the detection module 2 is at a low level, the output end of the chip U3 is also at a low level, the chip U3 is turned on, and the chip U3 compares the current detection signal input from the negative power supply feedback end of the operational amplifier U1A and the voltage detection signal sampled by the voltage divider sampling module 7 with the internal reference voltage of the chip U3, and outputs the control signal A2. The control signal A2 is input to the second port of the photocoupler U2, and the photocoupler U2 generates a feedback signal and feeds it back to the charger to adjust the actual charging voltage of the charger to reduce it, thereby limiting the maximum value of the actual charging voltage of the charger, and limiting the actual charging voltage of the charger to within a specified safe charging voltage range.

[0107] The beneficial effect of the technical solution of the present invention is that when the MCU or the detection circuit fails, the charging control circuit can still adjust the actual charging voltage and limit the actual charging voltage to within a preset safe charging voltage range to prevent the battery from overheating and being damaged, causing a combustion accident.

[0108] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation mode and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A charging control circuit, suitable for a charger, characterized in that: include: an optoelectronic coupling module, wherein an input end of the optoelectronic coupling module is connected to a detection module and a control module, an output end of the optoelectronic coupling module is connected to a voltage end of the charger, and a control end of the optoelectronic coupling module is connected to a primary side control chip of the charger; The photoelectric coupling module is used to generate a feedback signal according to the first control signal output by the detection module and feed it back to the charger to control the actual charging voltage and current of the charger; The detection module includes a voltage detection unit and a current detection unit, the output end of the voltage detection unit and the output end of the current detection unit together constitute the output end of the detection module, the input end of the voltage detection unit is used to detect the actual charging voltage of the charger, and the input end of the current detection unit is used to detect the actual charging current of the charger; The detection module is used to output the corresponding control signal according to the actual charging voltage and the actual charging current; a control module, wherein an input end of the control module is connected to a voltage end of the charger, an output end of the control module is connected to an input end of the photoelectric coupling module, and a ground end of the control module is grounded; The control module is used for: When the detection module outputs the first control signal normally, the control module is not turned on; When the detection module cannot normally output the first control signal, the control module is turned on, and generates a corresponding second control signal according to the input signal of the input end and sends it to the photoelectric coupling module, and the photoelectric coupling module generates the feedback signal according to the second control signal and feeds it back to the charger, so as to limit the actual charging voltage of the charger within a preset safe charging voltage range; The photoelectric coupling module includes a photoelectric coupler: The first pin of the photoelectric coupler is connected to the voltage end of the charger through a first resistor in series to form the output end of the photoelectric coupling module; The second pin of the photoelectric coupler serves as the input end of the photoelectric coupling module; The third pin of the photoelectric coupler is grounded; The fourth pin of the photoelectric coupler serves as the control end of the photoelectric coupling module; The current detection unit includes a first operational amplifier: The non-inverting input terminal of the first operational amplifier is connected to a current reference signal provided by an external micro control unit through a second resistor in series; The inverting input terminal of the first operational amplifier is connected to a current detection signal provided by an external micro control unit through a third resistor in series; The output end of the first operational amplifier is connected to the second pin of the photocoupler via a first diode in series; The voltage input terminal of the first operational amplifier is connected to a constant external voltage; The ground terminal of the first operational amplifier is grounded; The first operational amplifier is used to compare the current detection signal with the current reference signal, and output a corresponding first sub-control signal according to the comparison result; The control module includes a processing unit, and the processing unit includes: An input end connected to a second voltage-dividing sampling module, the second voltage-dividing sampling module is used to obtain a voltage detection signal after voltage-dividing sampling processing on the actual charging voltage input from the output end of the charger, and input the voltage detection signal to the first input end of the processing unit; An output terminal connected to the input terminal of the photoelectric coupling module; Ground terminal, connected to the ground wire; A third capacitor is connected between the input terminal and the output terminal of the processing unit by being connected in series with a ninth resistor.

2. A charging control circuit according to claim 1, characterized in that: The current detection unit also includes: A first capacitor is connected between the inverting input terminal and the output terminal of the first operational amplifier via a fourth resistor in series.

3. A charging control circuit according to claim 1, characterized in that: The voltage detection unit includes a second operational amplifier: The non-inverting input terminal of the second operational amplifier is connected to a voltage reference signal provided by an external micro control unit via a fifth resistor in series; The inverting input terminal of the second operational amplifier is connected to a first voltage-dividing sampling module, which is used to obtain a voltage detection signal after performing voltage-dividing sampling processing on the actual charging voltage input from the output terminal of the charger, and input the voltage detection signal to the inverting input terminal of the second operational amplifier; The output end of the second operational amplifier is connected to the second pin of the photocoupler via a second diode in series; The second operational amplifier is used to compare the voltage detection signal with the voltage reference signal, and output a corresponding second sub-control signal according to the comparison result.

4. A charging control circuit according to claim 3, characterized in that: The voltage detection unit also includes: A second capacitor is connected between the inverting input terminal and the output terminal of the second operational amplifier via a sixth resistor in series.

5. A charging control circuit according to claim 3, characterized in that: The first partial pressure sampling module comprises: a seventh resistor, the seventh resistor being connected in series between the inverting input terminal of the second operational amplifier and the output terminal of the charger; an eighth resistor, wherein the eighth resistor is connected in series between the inverting input terminal of the second operational amplifier and a ground terminal.

6. A charging control circuit according to claim 1, characterized in that: The second partial pressure sampling module comprises: a first adjustable resistor, the first adjustable resistor being connected in series between the voltage terminal of the charger and the input terminal of the processing unit; a second adjustable resistor, the second adjustable resistor being connected in series between the input terminal of the processing unit and a ground terminal; The first adjustable resistor and the second adjustable resistor are used to limit an upper limit value of the safe charging voltage range.

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