Lithium battery secondary overvoltage and overcharge protection system and control method

Abstract

The present invention provides a secondary overvoltage and overcharge protection system for lithium batteries and a control method thereof. The system includes: a control chip, a switch tube, and a three-terminal fuse. The control chip is used to receive a voltage signal of a lithium battery, and output a driving signal to the switch tube, and output a control signal to the three-terminal fuse. The switch tube is also connected to the negative electrode of the lithium battery. The switch tube is bolted to the three-terminal fuse through a patch nut so that the switch tube and the three-terminal fuse are connected in series. The three-terminal fuse is connected to the negative electrode of a load or a charger and directly outputs to the load or the charger. When the switch tube is not invalid, the control chip has a monitoring fault or the lithium battery voltage jumps, and the three-terminal fuse will not be triggered, ensuring the normal operation of the system. When the switch tube fails but the control chip monitors that the battery voltage reaches the limit setting threshold, the control chip sends a driving signal to control the three-terminal fuse to melt, thereby cutting off the main negative circuit and disconnecting charging, thereby achieving the effect of secondary overvoltage to prevent overcharging.

Description

Technical Field

[0001] The present invention belongs to the field of electronic circuit technology, and relates to lithium battery protection control technology, and in particular to a lithium battery secondary overvoltage and overcharge protection system and a control method. Background Art

[0002] The existing lithium battery protection system usually consists of a control chip, a switch tube, and a three-terminal fuse. The control chip monitors the status of the lithium battery to control the opening and closing of the switch tube, thereby achieving the charging on and off function. When all the switch tubes are damaged, the control chip directly controls the three-terminal fuse to blow when it detects that the lithium battery is still charging, thereby permanently disconnecting the main charging circuit. However, since many lithium battery protection systems have the same output port, the main circuit is cut off by controlling the positive electrode. This method will cause the complexity of the main positive circuit, and it is easy for the control chip to misjudge and cause the three-terminal fuse to be triggered incorrectly, which is easy to cause system failure and maintenance difficulties. Summary of the invention

[0003] In order to solve the complexity of installing the existing lithium battery secondary overvoltage and overcharge protection system in the main positive circuit and the maintenance technical problems after the system fails, the present invention provides a lithium battery secondary overvoltage and overcharge protection system, which can not only be directly installed in the main negative circuit, but also can easily determine whether the switch tube has failed, and reduce key maintenance problems.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A secondary overvoltage and overcharge protection system for lithium batteries includes a control chip, a switch tube, and a three-terminal fuse. The control chip is used to receive a voltage signal of the lithium battery, and output a drive signal to the switch tube and a control signal to the three-terminal fuse. The switch tube is also connected to the negative electrode of the lithium battery. The switch tube is bolted to the three-terminal fuse through a patch nut so that the switch tube and the three-terminal fuse are connected in series. The three-terminal fuse is connected to the negative electrode of the load or charger and directly outputs to the load or charger. The total positive electrode of the lithium battery is connected to the positive electrode of the load or charger.

[0006] Furthermore, the control chip model is SH367309.

[0007] Furthermore, the secondary overvoltage and overcharge protection system for lithium batteries includes: an open-drain resistor, a first control resistor, a second control resistor, a third control resistor, a fourth control resistor, a fifth control resistor, a sixth control resistor, a first control MOS tube, a second control MOS tube, a third control MOS tube, a first switch tube, a second switch tube, a freewheeling diode, and a three-terminal fuse; the three-terminal fuse, the first switch tube, and the second switch tube are connected in series with the total negative electrode of the lithium battery, the third control MOS tube and the second control MOS tube are connected in series, the first control MOS tube is connected to the total positive electrode of the lithium battery, the overcurrent ends 1 and 2 of the three-terminal fuse are connected in series with the first switch tube and the second switch tube, and the 4th and 5th pins are connected to the external load and the charger. The 3rd pin of the three-terminal fuse is connected to the 5th, 6th, 7th, and 8th pins of the first control MOS tube through a current storage diode, and the freewheeling diode is used to suppress the reverse voltage of the three-terminal fuse;

[0008] The open-drain resistor, the fifth control resistor and the sixth control resistor form a step-down control circuit for driving the second control MOS tube to open and close;

[0009] The third control resistor and the fourth control resistor form a driving circuit for driving the second control MOS tube to turn on and off;

[0010] The first control resistor and the second control resistor form a total voltage step-down circuit to drive the first control MOS tube to be turned on and off.

[0011] Furthermore, one end of the open-drain resistor is connected to the lithium battery signal B+master, and the other end is connected to one end of the fifth control resistor, and the other end of the fifth control resistor is respectively connected to one end of the sixth control resistor and the gate of the third control MOS tube; the other end of the sixth control resistor is grounded, the source of the third control MOS tube is grounded, and the drain is connected to the gate of the second control MOS tube.

[0012] Furthermore, one end of the third control resistor is connected to the lithium battery external power supply and the power pull-up signal B+, and the other end is connected to the second control MOS transistor gate. One end of the fourth control resistor is connected to the second control MOS transistor gate, and the other end is grounded.

[0013] Furthermore, one end of the first control resistor is connected to pin 3 of the first control MOS tube, and the other end is connected to one end of the second control resistor and pin 4 of the first control MOS tube, and the other end of the second control resistor is connected to the drain of the second control MOS tube.

[0014] Furthermore, the first control MOS tube Q1 is a PMOS tube.

[0015] A control method for a secondary overvoltage and overcharge protection system for a lithium battery comprises the following steps:

[0016] When the switch tube is not failed, the three-terminal fuse is not triggered and the system works normally; when the switch tube fails, the control chip detects that the lithium battery voltage rises to the limit set threshold, and sends a control signal to control the three-terminal fuse to melt, thereby cutting off the main negative circuit and disconnecting charging.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] When the switch tube is not failed or is working normally, the control chip has a monitoring fault or the lithium battery voltage jumps, and the three-terminal fuse will not be triggered, ensuring the normal operation of the system. When the switch tube fails but the control chip detects that the lithium battery voltage is still rising, when the battery voltage reaches the limit setting threshold, the control chip sends a drive signal to control the three-terminal fuse to melt, thereby cutting off the main negative circuit and disconnecting the charging, thereby achieving the effect of secondary overvoltage to prevent overcharging. Since the three-terminal fuse is bolted to the switch tube through a patch nut, it can be directly disassembled and replaced by the bolts, which is convenient for maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a functional block diagram of the lithium battery secondary overvoltage and overcharge protection system provided by the present invention.

[0020] Figure 2 It is a partial circuit diagram of the lithium battery secondary overvoltage and overcharge protection system provided by the present invention. DETAILED DESCRIPTION

[0021] The technical solution provided by the present invention will be described in detail below in conjunction with specific embodiments. It should be understood that the following specific implementation methods are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0022] The lithium battery secondary overvoltage and overcharge protection system provided by the present invention has an overall block diagram as shown in FIG. Figure 1 As shown, it includes a 309 control chip, a switch tube, and a three-terminal fuse, wherein the control chip receives the voltage signal of the lithium battery, outputs a driving signal to the switch tube, and outputs a control signal to the three-terminal fuse. The switch tube is connected to the negative electrode of the lithium battery, and the switch tube is bolted to the three-terminal fuse through a patch nut. The overcurrent ends of the three-terminal fuse are installed between the switch tube and the load or charger. Specifically, the three-terminal fuse is connected to the negative electrode of the load or charger and directly outputs to the load or charger. The total positive electrode of the lithium battery is connected to the positive electrode of the load or charger, and can be directly output to the load or charger. The control chip uses the SH367309 control chip.

[0023] The present invention also provides Figure 2A feasible circuit is shown in the figure, in which the open-drain resistor R6, the first control resistor R1, the second control resistor R2, the third control resistor R3, the fourth control resistor R4, the fifth control resistor R5, and the sixth control resistor R7 form a control chip. The first control MOS tube Q1, the second control MOS tube Q2, the third control MOS tube Q3, the first switch tube Q4, the second switch tube Q6, the freewheeling diode D1, and the three-terminal fuse F1 form a three-terminal FUSE, and the first switch tube Q4 and the second switch tube Q6 form Figure 1 The switch tube in is connected in series with the total negative electrode of the lithium battery. The third control MOS tube Q3 and the second control MOS tube Q2 are connected in series, the first control MOS tube Q1 is connected to the total positive electrode of the lithium battery, the overcurrent ends 1 and 2 of the three-terminal fuse F1 are connected in series with the first switch tube Q4 and the second switch tube Q6, and the 4 and 5 pins are connected to the external load and the charger. The 3rd pin of the three-terminal fuse is connected to the 5th, 6th, 7th and 8th pins of the first control MOS tube Q1 through the current storage diode D1. The freewheeling diode D1 is used to suppress the reverse voltage of the three-terminal fuse F1.

[0024] The open-drain resistor R6, the fifth control resistor R5, and the sixth control resistor R7 form a 12V step-down control circuit to drive the Q2MOS tube to open and close. Specifically, one end of the open-drain resistor R6 is connected to the lithium battery voltage signal B+master, and the other end is connected to one end of the fifth control resistor R5, and the other end of the fifth control resistor R5 is respectively connected to one end of the sixth control resistor R7 and the gate of the third control MOS tube Q3. The other end of the sixth control resistor R7 is grounded, the source of the third control MOS tube Q3 is grounded, and the drain is connected to the gate of the second control MOS tube Q2.

[0025] The third control resistor R3 and the fourth control resistor R4 form an 8V drive circuit to drive the Q2MOS tube to open and close. One end of the third control resistor R3 is connected to the lithium battery external power supply and the power pull-up signal B+, and the other end is connected to the gate of the second control MOS tube Q2. One end of the fourth control resistor R4 is connected to the gate of the second control MOS tube Q2, and the other end is grounded. The gate of the second control MOS tube Q2 is also connected to pin 1, the source is connected to pin 2, and the drain is connected to pin 3. When there is a signal at pin 1 of the MOS tube Q2, pins 2 and 3 of the MOS tube Q2 are connected.

[0026] The first control resistor R1 and the second control resistor R2 form a total voltage step-down circuit to drive the first control MOS tube Q1 to turn on and off. The first control resistor R1 is connected in parallel with the capacitor C1, one end of R1 is connected to the pin 3 of the first control MOS tube Q1, and the other end is connected to one end of the second control resistor R2 and the pin 4 of the first control MOS tube Q1. The other end of the second control resistor R2 is connected to the drain of the pin 3 of the second control MOS tube Q2. The first control MOS tube Q1 adopts a PMOS tube, and the packaged chip HY06p10s is used in this example.

[0027] When the switch tube is not damaged or failed, the three-terminal fuse will not be easily triggered by mistake after the lithium battery voltage jumps or the system fails. At the same time, the switch tube fails or is damaged. When the lithium battery is still charging when the switch tube fails, the control chip detects that the lithium battery voltage is still rising. When the battery voltage reaches the limit setting threshold, the SH367309 control chip sends a drive signal to control the three-terminal fuse to melt, thereby cutting off the main negative circuit and disconnecting the charging, thereby achieving the effect of secondary overvoltage to prevent overcharging. After the three-terminal fuse is damaged, it can be directly disassembled and replaced by bolts.

[0028] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. The secondary overvoltage and overcharge protection system for lithium batteries is characterized by: include: A control chip, a switch tube, and a three-terminal fuse. The control chip is used to receive a voltage signal of a lithium battery, and output a driving signal to the switch tube, and output a control signal to the three-terminal fuse. The switch tube is also connected to the negative electrode of the lithium battery. The switch tube is bolted to the three-terminal fuse through a patch nut so that the switch tube and the three-terminal fuse are connected in series. The three-terminal fuse is connected to the negative electrode of the load or charger and directly outputs to the load or charger. The total positive electrode of the lithium battery is connected to the positive electrode of the load or charger. The secondary overvoltage and overcharge protection system for lithium batteries includes: an open-drain resistor, a first control resistor, a second control resistor, a third control resistor, a fourth control resistor, a fifth control resistor, a sixth control resistor, a first control MOS tube, a second control MOS tube, a third control MOS tube, a first switch tube, a second switch tube, a freewheeling diode, and a three-terminal fuse; the three-terminal fuse, the first switch tube, and the second switch tube are connected in series with the total negative electrode of the lithium battery, the third control MOS tube and the second control MOS tube are connected in series, the first control MOS tube is connected to the total positive electrode of the lithium battery, the overcurrent ends 1 and 2 of the three-terminal fuse are connected in series with the first switch tube and the second switch tube, and the 4th and 5th pins are connected to the external load and the charger; the 3rd pin of the three-terminal fuse is connected to the 5th, 6th, 7th, and 8th pins of the first control MOS tube through a current storage diode, and the freewheeling diode is used to suppress the reverse voltage of the three-terminal fuse; The open-drain resistor, the fifth control resistor and the sixth control resistor form a step-down control circuit for driving the second control MOS tube to open and close; The third control resistor and the fourth control resistor form a driving circuit for driving the second control MOS tube to turn on and off; The first control resistor and the second control resistor form a total voltage step-down circuit to drive the first control MOS tube to turn on and off; One end of the open-drain resistor is connected to the lithium battery signal B+master, and the other end is connected to one end of the fifth control resistor, and the other end of the fifth control resistor is respectively connected to one end of the sixth control resistor and the gate of the third control MOS tube; the other end of the sixth control resistor is grounded, the source of the third control MOS tube is grounded, and the drain is connected to the gate of the second control MOS tube; One end of the third control resistor is connected to the lithium battery external power supply and the power pull-up signal B+, and the other end is connected to the gate of the second control MOS tube. One end of the fourth control resistor is connected to the gate of the second control MOS tube, and the other end is grounded; One end of the first control resistor is connected to pin 3 of the first control MOS tube, and the other end is connected to one end of the second control resistor and pin 4 of the first control MOS tube. The other end of the second control resistor is connected to the drain of the second control MOS tube.

2. The lithium battery secondary overvoltage and overcharge protection system according to claim 1, characterized in that: The control chip model is SH367309.

3. The lithium battery secondary overvoltage and overcharge protection system according to claim 1, characterized in that: The first control MOS tube Q1 is a PMOS tube.

4. A control method for a lithium battery secondary overvoltage and overcharge protection system, based on the lithium battery secondary overvoltage and overcharge protection system according to any one of claims 1 to 3, comprises the following steps: When the switch tube is not failed, the three-terminal fuse is not triggered and the system works normally; when the switch tube fails, the control chip detects that the lithium battery voltage rises to the limit set threshold, and sends a control signal to control the three-terminal fuse to melt, thereby cutting off the main negative circuit and disconnecting charging.

Images