Detection circuit of lithium battery charger and lithium battery charger

Abstract

The utility model provides a detection circuit of a lithium battery charger and the lithium battery charger. The detection circuit comprises a detection module, a first amplification module and a second amplification module. A first input end of the detection module is electrically connected to a target IO port of an MCU of a target charger, a first output end of the detection module is grounded, a second input end of the detection module is electrically connected to a first output end of the first amplification module, and a second output end of the detection module and a first output end of the second amplification module are both electrically connected to a negative electrode of a target lithium battery; the input end of the first amplification module is electrically connected to the positive electrode of a target charger or a target lithium battery, and the second output end of the first amplification module is electrically connected to the input end of the second amplification module; the second output end of the second amplification module is electrically connected to the negative electrode of the target charger. According to the technical scheme, the lithium battery BMS system can detect the output of the charger when the charging MOS tube is closed.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, in particular to a detection circuit of a lithium battery charger and a lithium battery charger. Background Art

[0002] Currently, lithium batteries will shut down the charging MOS tube due to certain conditions or faults. After the charging MOS tube is turned off, the BMS system in the battery product cannot use the charging current to detect whether there is a charger, so the charger cannot be used to perform some functions or release certain conditions.

[0003] Based on the above requirements, it is necessary to design a detection circuit that can still detect the charger output when the lithium battery BMS system is in the charging MOS tube turned off, so as to give the BMS system more operating space. Utility Model Content

[0004] The embodiments of the present invention provide a detection circuit for a lithium battery charger and a lithium battery charger, so as to detect the charger output even when the charging MOS tube of the lithium battery BMS system is turned off.

[0005] In order to achieve the above objectives, in a first aspect, the present invention provides a detection circuit for a lithium battery charger, comprising:

[0006] a detection module, a first amplification module, and a second amplification module;

[0007] The first input end of the detection module is electrically connected to the target IO port of the MCU of the target charger, the first output end of the detection module is grounded, the second input end of the detection module is electrically connected to the first output end of the first amplification module, and the second output end of the detection module and the first output end of the second amplification module are both electrically connected to the negative electrode of the target lithium battery;

[0008] The input end of the first amplifying module is electrically connected to the positive electrode of the target charger or the target lithium battery, and the second output end of the first amplifying module is electrically connected to the input end of the second amplifying module;

[0009] The second output end of the second amplifying module is electrically connected to the negative electrode of the target charger;

[0010] Wherein, the target IO port is configured as a high input detection, and the detection module is configured to pull down the level of the first input terminal of the detection module if it receives an input from the target charger or the positive electrode of the target lithium battery when the MOS tube of the BMS of the target lithium battery is turned off. Wherein, the target IO port is configured as a high input detection, and the detection module is configured to pull down the level of the first input terminal of the detection module if it receives an input from the target charger or the positive electrode of the target lithium battery when the MOS tube of the BMS of the target lithium battery is turned off;

[0011] The first amplification module is configured to, when the MOS tube of the BMS of the target lithium battery is turned on, make the first amplification module, the second amplification module and the detection module non-conductive; when the MOS tube of the BMS of the target lithium battery is turned off, make the first amplification module, the second amplification module and the detection module all conductive, and pull down the level of the first input end of the detection module.

[0012] Furthermore, the detection module is a photoelectric coupler, the first input end of the detection module is the input end of the light detector of the photoelectric coupler, the second input end of the detection module is the input end of the light-emitting diode of the photoelectric coupler, the first output end of the detection module is the output end of the light detector of the photoelectric coupler, and the second output end of the detection module is the output end of the light-emitting diode of the photoelectric coupler.

[0013] Furthermore, it also includes:

[0014] A first resonant circuit, wherein the first resonant circuit includes a first resistor and a first capacitor, one end of the first resistor is electrically connected to the target IO port, the other end of the first resistor is electrically connected to the first input end of the detection module, one end of the first capacitor is electrically connected to the target IO port, and the other end of the first capacitor is grounded.

[0015] Furthermore, the first amplifying module includes a first transistor, a second resistor and a third resistor;

[0016] The first transistor is a PNP transistor, the collector of the first transistor is electrically connected to the second resistor and then electrically connected to the second input end of the detection module, the emitter of the first transistor is electrically connected to the third resistor and then electrically connected to the positive electrode of the target charger or the target lithium battery, and the base of the first transistor is electrically connected to the input end of the second amplification module.

[0017] Furthermore, the second amplifying module includes a second transistor, a fourth resistor, a fifth resistor and a Schottky diode;

[0018] The second transistor is an NPN transistor, the emitter of the second transistor is electrically connected to the Schottky diode and then electrically connected to the negative electrode of the target charger, the collector of the second transistor is electrically connected to the fourth resistor and then electrically connected to the second output end of the first amplification module, and the base of the second transistor is electrically connected to the fifth resistor and then electrically connected to the negative electrode of the target lithium battery.

[0019] Furthermore, it also includes:

[0020] A second resonant circuit, the second resonant circuit includes a sixth resistor and a second capacitor, one end of the sixth resistor is electrically connected to the base of the second transistor, the other end of the sixth resistor is electrically connected to the input end of the Schottky diode, one end of the second capacitor is electrically connected to the base of the second transistor, and the other end of the second capacitor is electrically connected to the input end of the Schottky diode.

[0021] Furthermore, the capacitors in the detection circuit are all 0603 package capacitors, and the resistors in the detection circuit are all 0603 package resistors.

[0022] In a second aspect, the present invention further provides a lithium battery charger, comprising a charger body and a detection circuit of the lithium battery charger as described in any one of the first aspects.

[0023] The above technical solution has the following technical effects:

[0024] When the MOS tube of the BMS of the target lithium battery is turned on, the negative electrode of the target lithium battery and the negative electrode of the target charger are almost short-circuited, making the second amplifier module non-conductive, and then the first amplifier module non-conductive, and finally the detection module non-conductive. Therefore, the target IO port of the MCU of the target charger still detects a high level and believes that no charger is connected;

[0025] When the MOS tube of the BMS of the target lithium battery is turned off, if there is input from the target charger or the positive electrode of the target lithium battery, the voltage between the negative electrode of the target lithium battery and the negative electrode of the target charger is equal to the voltage of the target charger minus the voltage of the target lithium battery, which turns on the second amplification module, and then turns on the first amplification module, and finally turns on the detection module and pulls down the voltage of the target IO port of the MCU of the target charger. Therefore, the target IO port of the MCU of the target charger detects a low level, which means that a charger is connected;

[0026] The lithium battery BMS system can detect the charger output even when the charging MOS tube is turned off. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a structural diagram of the first embodiment of the present utility model;

[0028] Figure 2 This is a circuit diagram of the second embodiment of the present utility model;

[0029] Figure 3 for Figure 2 A conduction schematic diagram in working state;

[0030] Figure 4 for Figure 2 Another conduction diagram in the working state. DETAILED DESCRIPTION

[0031] To further illustrate various embodiments, the present invention is provided with accompanying drawings. These drawings form part of the disclosure of this invention and are primarily used to illustrate the embodiments and, in conjunction with the relevant description in the specification, to explain the operating principles of the embodiments. By referring to these drawings, those skilled in the art will understand other possible implementations and the advantages of this invention. The components in the figures are not drawn to scale, and similar reference numerals are generally used to represent similar components.

[0032] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0033] Example 1:

[0034] A first embodiment of a detection circuit for a lithium battery charger, referring to Figure 1 ,include:

[0035] a detection module, a first amplification module, and a second amplification module;

[0036] The first input end of the detection module is electrically connected to the target IO port of the MCU of the target charger, the first output end of the detection module is grounded, the second input end of the detection module is electrically connected to the first output end of the first amplification module, and the second output end of the detection module and the first output end of the second amplification module are both electrically connected to the negative electrode of the target lithium battery;

[0037] The input end of the first amplifying module is electrically connected to the positive electrode of the target charger or the target lithium battery, and the second output end of the first amplifying module is electrically connected to the input end of the second amplifying module;

[0038] The second output end of the second amplifying module is electrically connected to the negative electrode of the target charger;

[0039] The target IO port is configured to be set to high input detection, and the detection module is configured to pull down the level of the first input terminal of the detection module if it receives input from the target charger or the positive electrode of the target lithium battery when the MOS tube of the BMS of the target lithium battery is turned off;

[0040] The first amplification module is configured to, when the MOS tube of the BMS of the target lithium battery is turned on, make the first amplification module, the second amplification module and the detection module non-conductive; when the MOS tube of the BMS of the target lithium battery is turned off, make the first amplification module, the second amplification module and the detection module all conductive, and pull down the level of the first input end of the detection module.

[0041] Optionally, the detection module is a photoelectric coupler, the first input end of the detection module is the input end of the light detector of the photoelectric coupler, the second input end of the detection module is the input end of the light-emitting diode of the photoelectric coupler, the first output end of the detection module is the output end of the light detector of the photoelectric coupler, and the second output end of the detection module is the output end of the light-emitting diode of the photoelectric coupler.

[0042] In this embodiment, when the first amplifying module is not conducting, the light-emitting diode itself is also not conducting, and the light detector cannot generate light-induced current. Therefore, the target IO port of the MCU of the target charger detects that it is still at a high level and believes that no charger is connected.

[0043] When the first amplifying module is turned on, the light emitting diode turns on itself, causing the light detector to generate light-induced current, pulling down the voltage of the target IO port of the MCU of the target charger. Therefore, the target IO port of the MCU of the target charger detects a low level, which means that a charger is connected.

[0044] Optionally, also include:

[0045] A first resonant circuit, wherein the first resonant circuit includes a first resistor and a first capacitor, one end of the first resistor is electrically connected to the target IO port, the other end of the first resistor is electrically connected to the first input end of the detection module, one end of the first capacitor is electrically connected to the target IO port, and the other end of the first capacitor is grounded.

[0046] This embodiment can not only better realize signal transmission and conversion, but also realize signal isolation and protection.

[0047] Optionally, the first amplifying module includes a first transistor, a second resistor and a third resistor;

[0048] The first transistor is a PNP transistor, the collector of the first transistor is electrically connected to the second resistor and then electrically connected to the second input end of the detection module, the emitter of the first transistor is electrically connected to the third resistor and then electrically connected to the positive electrode of the target charger or the target lithium battery, and the base of the first transistor is electrically connected to the input end of the second amplification module.

[0049] Optionally, the second amplifying module includes a second transistor, a fourth resistor, a fifth resistor and a Schottky diode;

[0050] The second transistor is an NPN transistor, the emitter of the second transistor is electrically connected to the Schottky diode and then electrically connected to the negative electrode of the target charger, the collector of the second transistor is electrically connected to the fourth resistor and then electrically connected to the second output end of the first amplification module, and the base of the second transistor is electrically connected to the fifth resistor and then electrically connected to the negative electrode of the target lithium battery.

[0051] In this embodiment, when the MOS tube of the BMS of the target lithium battery is turned on, the negative electrode of the target lithium battery and the negative electrode of the target charger are approximately short-circuited. There is no bias voltage between the B and E poles of the second transistor, making the second transistor non-conductive, which in turn makes the first transistor non-conductive, and finally makes the detection module non-conductive. Therefore, the target IO port of the MCU of the target charger detects that it is still at a high level, and it is considered that no charger is connected.

[0052] When the MOS tube of the BMS of the target lithium battery is turned off, if there is input from the target charger or the positive electrode of the target lithium battery, the voltage between the negative electrode of the target lithium battery and the negative electrode of the target charger is equal to the voltage of the target charger minus the voltage of the target lithium battery. Since the output voltage of the target charger must be greater than the voltage of the target lithium battery in order for the target lithium battery to be charged, the voltage between the negative electrode of the target lithium battery and the negative electrode of the target charger must be positive at this time;

[0053] However, the voltage between the negative electrode of the target lithium battery and the negative electrode of the target charger is greater than the base forward voltage of the second transistor plus the conduction voltage of the Schottky diode, so that a certain base current flows through the second transistor, which can turn on the second transistor. As the second transistor is turned on, the base voltage of the first transistor is pulled down, and there is a current loop from the positive electrode of the target charger to the negative electrode of the target charger, which causes the first transistor to also turn on.

[0054] Since the first transistor is turned on, the voltage of the positive electrode of the target charger or target lithium battery can be applied to the second input terminal of the detection module, which eventually turns on the detection module and pulls down the voltage of the target IO port of the MCU of the target charger. Therefore, the target IO port of the MCU of the target charger detects a low level, which means that there is a charger connected;

[0055] At the same time, since two transistors are used for two-stage amplification, even when the voltage difference between the target charger output voltage and the target lithium battery voltage is very small, a sufficiently large current can be obtained to drive the detection module.

[0056] Further optional features include:

[0057] A second resonant circuit, the second resonant circuit includes a sixth resistor and a second capacitor, one end of the sixth resistor is electrically connected to the base of the second transistor, the other end of the sixth resistor is electrically connected to the input end of the Schottky diode, one end of the second capacitor is electrically connected to the base of the second transistor, and the other end of the second capacitor is electrically connected to the input end of the Schottky diode.

[0058] By adopting this embodiment, the stability and reliability of the amplifier circuit can be improved.

[0059] Optionally, the capacitors in the detection circuit are all 0603 package capacitors, and the resistors in the detection circuit are all 0603 package resistors.

[0060] By adopting this embodiment, the stability and reliability of the circuit can be further improved, while ensuring a good frequency response.

[0061] Example 2:

[0062] A second embodiment of a detection circuit for a lithium battery charger, referring to Figure 2 In this embodiment, the capacitors in the detection circuit are all 0603 package capacitors, and the resistors in the detection circuit are all 0603 package resistors.

[0063] The detection module is a photoelectric coupler OC1, the first input end of the detection module is the input end of the light detector of the photoelectric coupler OC1, the second input end of the detection module is the input end of the light-emitting diode of the photoelectric coupler OC1, the first output end of the detection module is the output end of the light detector of the photoelectric coupler OC1, and the second output end of the detection module is the output end of the light-emitting diode of the photoelectric coupler OC1.

[0064] It also includes a first resonant circuit, which includes a first resistor R1 and a first capacitor, one end of the first resistor R1 is electrically connected to the target IO port, the other end of the first resistor R1 is electrically connected to the first input end of the detection module, one end of the first capacitor is electrically connected to the target IO port, and the other end of the first capacitor is grounded.

[0065] The first amplifying module includes a first transistor Q1, a second resistor R2 and a third resistor R3;

[0066] The first transistor Q1 is a PNP transistor, the collector of the first transistor Q1 is electrically connected to the second resistor R2 and then electrically connected to the second input end of the detection module, the emitter of the first transistor Q1 is electrically connected to the third resistor R3 and then electrically connected to the positive electrode IN+ of the target charger or the target lithium battery, and the base of the first transistor Q1 is electrically connected to the input end of the second amplification module.

[0067] The second amplifying module includes a second transistor Q2, a fourth resistor R4, a fifth resistor R5 and a Schottky diode DS1;

[0068] The second transistor Q2 is an NPN transistor, the emitter of the second transistor Q2 is electrically connected to the Schottky diode DS1 and then electrically connected to the negative electrode P- of the target charger, the collector of the second transistor Q2 is electrically connected to the fourth resistor R4 and then electrically connected to the second output end of the first amplification module, and the base of the second transistor Q2 is electrically connected to the fifth resistor R5 and then electrically connected to the negative electrode B- of the target lithium battery.

[0069] It also includes a second resonant circuit, which includes a sixth resistor R6 and a second capacitor, one end of the sixth resistor R6 is electrically connected to the base of the second transistor Q2, and the other end of the sixth resistor R6 is electrically connected to the input end of the Schottky diode DS1, one end of the second capacitor is electrically connected to the base of the second transistor Q2, and the other end of the second capacitor is electrically connected to the input end of the Schottky diode DS1.

[0070] Therefore, in this embodiment, when the MOS tube of the BMS of the target lithium battery is turned on, the negative electrode B- of the target lithium battery and the negative electrode P- of the target charger are approximately short-circuited. There is no bias voltage between the B and E poles of the second transistor Q2, making the second transistor Q2 non-conductive, which in turn makes the first transistor Q1 non-conductive, and finally makes the photocoupler OC1 non-conductive. Therefore, the target IO port of the MCU of the target charger detects that it is still at a high level and believes that no charger is connected.

[0071] Reference Figure 3 When the MOS tube of the BMS of the target lithium battery is turned off, if there is input from the target charger or the positive electrode IN+ of the target lithium battery, the voltage between the negative electrode B- of the target lithium battery and the negative electrode P- of the target charger is equal to the voltage of the target charger minus the voltage of the target lithium battery. Since the output voltage of the target charger must be greater than the voltage of the target lithium battery in order for the target lithium battery to be charged, the voltage between the negative electrode B- of the target lithium battery and the negative electrode P- of the target charger must be positive at this time;

[0072] However, the voltage between the negative electrode B- of the target lithium battery and the negative electrode P- of the target charger is greater than the base forward voltage of the second transistor Q2 plus the conduction voltage of the Schottky diode DS1, so that a certain base current flows in the second transistor Q2, which can turn on the second transistor Q2. As the second transistor Q2 is turned on, the base voltage of the first transistor Q1 is pulled down, and there is a current loop from the positive electrode of the target charger to the negative electrode of the target charger, which causes the first transistor Q1 to also turn on.

[0073] Reference Figure 4 Since the first transistor Q1 is turned on, the voltage of the positive electrode IN+ of the target charger or target lithium battery can be applied to the second input terminal of the photocoupler OC1, which eventually turns on the photocoupler OC1 and pulls down the voltage of the target IO port of the target charger's MCU. Therefore, the target IO port of the target charger's MCU detects a low level, which means that a charger is connected;

[0074] At the same time, since two transistors are used for two-stage amplification, even if there is a voltage difference (V B-P- ) is very small, it can also obtain a large enough current to drive the optocoupler OC1. Referring to Table 1 and Table 2, it can be clearly seen that through the secondary amplifier circuit, the voltage difference of only 0.68V is needed to turn on the optocoupler OC1, which is much lower than the 0.88V of the primary amplifier circuit.

[0075] <![CDATA[V B-P- Voltage (V) Optocoupler input current (uA) Optocoupler output status 0.7 2.58 No continuity 0.8 143 No continuity 0.85 387 No continuity 0.88 424 conduction

[0076] Table 1 (First-stage current amplification)

[0077] <![CDATA[V B-P- Voltage (V) Optocoupler input current (uA) Power supply 3 voltage (V) 0 0 No continuity 0.5 2.5 No continuity 0.6 133 No continuity 0.68 483 conduction 0.7 3078 conduction

[0078] Table 2 (Secondary Current Amplification)

[0079] Example 3:

[0080] The utility model also provides a lithium battery charger, which is characterized by comprising a charger body and a detection circuit as described in any one of the above lithium battery chargers.

[0081] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, those skilled in the art should understand that various changes can be made to the form and details of the present invention without departing from the spirit and scope of the present invention as defined by the appended claims, and all of these changes are within the scope of protection of the present invention.

Claims

1. A detection circuit for a lithium battery charger, characterized in that: include: a detection module, a first amplification module, and a second amplification module; The first input end of the detection module is electrically connected to the target IO port of the MCU of the target charger, the first output end of the detection module is grounded, the second input end of the detection module is electrically connected to the first output end of the first amplification module, and the second output end of the detection module and the first output end of the second amplification module are both electrically connected to the negative electrode of the target lithium battery; The input end of the first amplifying module is electrically connected to the positive electrode of the target charger or the target lithium battery, and the second output end of the first amplifying module is electrically connected to the input end of the second amplifying module; The second output end of the second amplifying module is electrically connected to the negative electrode of the target charger; The target IO port is configured to be set to high input detection, and the detection module is configured to pull down the level of the first input terminal of the detection module if it receives input from the target charger or the positive electrode of the target lithium battery when the MOS tube of the BMS of the target lithium battery is turned off; The first amplification module is configured to, when the MOS tube of the BMS of the target lithium battery is turned on, make the first amplification module, the second amplification module and the detection module non-conductive; when the MOS tube of the BMS of the target lithium battery is turned off, make the first amplification module, the second amplification module and the detection module all conductive, and pull down the level of the first input end of the detection module.

2. The detection circuit of the lithium battery charger according to claim 1, characterized in that: The detection module is a photoelectric coupler, the first input end of the detection module is the input end of the light detector of the photoelectric coupler, the second input end of the detection module is the input end of the light emitting diode of the photoelectric coupler, the first output end of the detection module is the output end of the light detector of the photoelectric coupler, and the second output end of the detection module is the output end of the light emitting diode of the photoelectric coupler.

3. The detection circuit of the lithium battery charger according to claim 1, characterized in that: Also includes: A first resonant circuit, wherein the first resonant circuit includes a first resistor and a first capacitor, one end of the first resistor is electrically connected to the target IO port, the other end of the first resistor is electrically connected to the first input end of the detection module, one end of the first capacitor is electrically connected to the target IO port, and the other end of the first capacitor is grounded.

4. The detection circuit of the lithium battery charger according to claim 1, characterized in that: The first amplifying module includes a first transistor, a second resistor and a third resistor; The first transistor is a PNP transistor, the collector of the first transistor is electrically connected to the second resistor and then electrically connected to the second input end of the detection module, the emitter of the first transistor is electrically connected to the third resistor and then electrically connected to the positive electrode of the target charger or the target lithium battery, and the base of the first transistor is electrically connected to the input end of the second amplification module.

5. The detection circuit of the lithium battery charger according to claim 1, characterized in that: The second amplifying module includes a second triode, a fourth resistor, a fifth resistor and a Schottky diode; The second transistor is an NPN transistor, the emitter of the second transistor is electrically connected to the Schottky diode and then electrically connected to the negative electrode of the target charger, the collector of the second transistor is electrically connected to the fourth resistor and then electrically connected to the second output end of the first amplification module, and the base of the second transistor is electrically connected to the fifth resistor and then electrically connected to the negative electrode of the target lithium battery.

6. The detection circuit of the lithium battery charger according to claim 5, characterized in that: Also includes: A second resonant circuit, the second resonant circuit includes a sixth resistor and a second capacitor, one end of the sixth resistor is electrically connected to the base of the second transistor, the other end of the sixth resistor is electrically connected to the input end of the Schottky diode, one end of the second capacitor is electrically connected to the base of the second transistor, and the other end of the second capacitor is electrically connected to the input end of the Schottky diode.

7. The detection circuit of the lithium battery charger according to claim 1, characterized in that: The capacitors in the detection circuit are all 0603 package capacitors, and the resistors in the detection circuit are all 0603 package resistors.

8. A lithium battery charger, characterized in that: The invention comprises a charger body and a detection circuit of a lithium battery charger as claimed in any one of claims 1 to 7.

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