Battery protection circuit

Abstract

The utility model relates to a battery protection circuit, which is used for monitoring faults of a control circuit of a battery and comprises a BMS module and an MCU module which are arranged at two ends of the battery in parallel, a main switch K1 is connected between the battery and a charger in series, the BMS module is communicated with the main switch K1 through an auxiliary switch K2, and the MCU module is connected with the auxiliary switch K2 through an AC module. A main switch K1 and an auxiliary switch K2 are arranged in a circuit, under the normal condition, the BMS module drives the main switch K1 to be switched off when detecting that the circuit is abnormal, and the MCU controls the auxiliary switch K1 to be switched off when detecting that the BMS module is invalid, so that a control signal of the BMS cannot reach a control port of the main switch K1, the K1 is switched off, and when the MCU module is invalid, the main switch K1 is switched off. The signal of the MCU module cannot reach the auxiliary switch K2 after being converted by the AC module, so that the control signal of the BMS module cannot reach the control port of the main switch K1, and the K1 is switched off.

Description

Technical Field

[0001] The utility model relates to the field of protection circuits, and in particular to a battery protection circuit. Background Art

[0002] A battery is a cup, tank or other container or part of a composite container that contains electrolyte solution and metal electrodes to generate electric current. It is a device that can convert chemical energy into electrical energy. It has a positive electrode and a negative electrode. With the advancement of technology, batteries generally refer to small devices that can generate electrical energy. Batteries are divided into dry batteries, lead-acid batteries, lithium batteries, sodium-ion batteries, etc.

[0003] Battery packs are often used in bicycles, forklifts, golf carts, etc. with low mileage. During the use of the battery pack, internal short circuits may occur due to damage to the circuit-breaking devices, causing overcharging of the battery pack, high temperature, high voltage and high current, and explosion or fire of the battery pack, resulting in a large number of safety hazards during the use of electric vehicles. Summary of the invention

[0004] In order to achieve the purpose of this utility, the technical solution adopted by this utility is: a battery protection circuit, used for battery control circuit fault monitoring, including: a BMS module and an MCU module arranged in parallel at both ends of the battery, a main switch K1 is connected in series between the battery and the charger, the BMS module is connected to the main switch K1 through the auxiliary switch K2, and the MCU module is connected to the auxiliary switch K2 through the AC module. By setting the main switch K1 and the auxiliary switch K2 in the circuit, under normal circumstances, when the BMS module detects that the circuit is abnormal, it will drive the main switch K1 to disconnect, and when the circuit is detected to be in failure of the BMS module, the MCU controls the auxiliary switch K1 to disconnect, so that the control signal of the BMS cannot reach the control port of the main switch K1, and K1 is disconnected. When the MCU module fails, the signal of the MCU module cannot reach the auxiliary switch K2 after conversion through the AC module. Therefore, the control signal of the BMS module cannot reach the control port of the main switch K1, and K1 is disconnected. Through the cooperation of the AC module, the main switch K1 and the auxiliary switch K2, the circuit is improved in the case of failure of different modules, and the safety hazards during the use of electric vehicles are reduced.

[0005] Preferably, the MCU module includes: an input end and a capacitor C44, the capacitor C44 is connected to a diode D6, the diode D6 is connected to a capacitor C45 and an input resistor R112, the input resistor R112 is connected to a resistor R113 and PIN1 of a transistor Q32, PIN3 of the transistor Q32 is connected to a discharge control signal DSG through a transistor Q34, and is also connected to VDD through a resistor R115, and PIN3 of the transistor Q32 is connected to a charging control signal CHG through a transistor Q35.

[0006] Preferably, the MCU module is also provided with a current detection circuit and a fuse blowing control circuit. When the current detection circuit detects that the load exceeds the rated maximum value, the fuse blowing control circuit will be activated to blow.

[0007] Preferably, the current detection circuit includes: a current detection amplifier, PIN1 of the current detection amplifier is connected to the ADC current of the MCU module, PIN2 of the current detection amplifier is grounded, PIN3 of the current detection amplifier is connected to the SRP of the circuit, PIN4 of the current detection amplifier is connected to the SRN of the circuit, R151, R152, R156 and R159 are connected between SRP and SRN; PIN5 of the current detection amplifier is connected to VDD.

[0008] Preferably, the fuse blowing control circuit includes: one end of a resistor R52 connected to the MCU fuse, the other end of the resistor R52 is connected to a resistor R54 and PIN1 of a transistor Q15, the other end of the resistor R54 is grounded, the PIN2 of the transistor Q15 is grounded, the PIN3 of the transistor Q15 is connected to a resistor R42, the other end of the resistor R42 is connected to PIN1 of a switch MOS tube Q18, a voltage regulator diode D2 and a resistor R39, the resistor R39 is connected to the voltage regulator diode D2 and then to PIN3 of the switch MOS tube Q18 and a fuse F3, the other end of the fuse F3 is connected to a thyristor bat16; PIN3 of the switch MOS tube Q18 is connected to a resistor R44 and a dedicated fuse for the battery pack.

[0009] Compared with the prior art, the beneficial effects of this invention are:

[0010] 1. By setting the main switch K1 and the auxiliary switch K2 in the circuit, under normal circumstances, when the BMS module detects that the circuit is abnormal, it will drive the main switch K1 to be disconnected. When the circuit is detected to be faulty by the BMS module, the MCU controls the auxiliary switch K1 to be disconnected, so that the control signal of the BMS cannot reach the control port of the main switch K1, and K1 is disconnected. When the MCU module fails, the signal of the MCU module cannot be converted by the AC module and reach the auxiliary switch K2. Therefore, the control signal of the BMS module cannot reach the control port of the main switch K1, and K1 is disconnected. Through the cooperation of the AC module, the main switch K1 and the auxiliary switch K2, the circuit can improve the safety of the circuit when different modules fail, thereby reducing the potential safety hazards during the use of electric vehicles.

[0011] 2. The maximum load of the circuit is determined by the current detection circuit. When the circuit load exceeds the rated maximum value, the fuse blowing control circuit will be activated to blow. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1This is a module connection diagram for a battery protection circuit used in this utility;

[0013] Figure 2 This is an MCU control circuit for a battery protection circuit;

[0014] Figure 3 The present invention is a current detection circuit for a battery protection circuit;

[0015] Figure 4 This is an MCU fuse fusing control circuit for a battery protection circuit;

[0016] Figure 5 This is the overall circuit connection diagram of the battery protection circuit used in this utility model. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the practical embodiment to clearly and completely describe the technical solution in the practical embodiment. Obviously, the described embodiment is only a part of the embodiment of the practical embodiment, not all of the embodiments. Based on the embodiment in the practical embodiment, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this practical embodiment.

[0018] like Figures 1 to 5 As shown, the present invention provides a technical solution: a battery protection circuit for battery control circuit fault monitoring, including: a BMS module and an MCU module arranged in parallel at both ends of the battery, a main switch K1 is connected in series between the battery and the charger, the BMS module is connected to the main switch K1 through an auxiliary switch K2, and the MCU module is connected to the auxiliary switch K2 through an AC module.

[0019] Among them, the MCU module includes: an input end and a capacitor C44, the capacitor C44 is connected to a diode D6, the diode D6 is connected to a capacitor C45 and an input resistor R112, the input resistor R112 is connected to a resistor R113 and PIN1 of a transistor Q32, PIN3 of the transistor Q32 is connected to a discharge control signal DSG through a transistor Q34, and is also connected to VDD through a resistor R115, and PIN3 of the transistor Q32 is connected to a charging control signal CHG through a transistor Q35.

[0020] Among them, the resistor R114 is the ground discharge circuit of the capacitor C44, which releases the charge of the capacitor in static state, and the resistor R112 is the input resistor of the back-end transistor Q32, which plays the role of current limiting and protecting the transistor;

[0021] Resistor R113 is the ground discharge circuit of capacitor C45, which releases the charge on the capacitor when static, and also ensures that the base voltage of the subsequent transistor Q32 is low when static.

[0022] The resistor R115 is the collector pull-up resistor of the transistor Q32, the resistor R116 is the base input current limiting protection resistor of the transistor Q34; the resistor R117 is the base input current limiting protection resistor of the transistor Q35;

[0023] Under normal circumstances, the MCU module will not interfere with the action of the main switch K1, and the main switch K1 is completely controlled by the BMS module. At this time, the MCU module outputs a valid AC signal to the AC module, so that the auxiliary switch K2 is in a closed state, and the control signal of the BMS module can reach the control port of the main switch K1 normally. The BMS module controls the action logic of the main switch K1 according to the current battery voltage, current, temperature and other information;

[0024] MCU_MOS_PWM outputs 3.3V PWM with a certain frequency (continuous high and low levels), which is coupled to the back end through capacitor C44, and then rectified and filtered by D6 / C45 to become an approximate DC level signal higher than 0.7V to Q32 PIN1.

[0025] The DC signal turns on transistor Q32, so that Q32 obtains a low level at PIN3, thereby making PIN3 of the back-end transistor Q34 / Q35 a high impedance state;

[0026] At this time, the discharge control signal DSG and the charge control signal CHG can output high and low levels normally, control the working condition of the output MOS module, and output the status according to the system needs;

[0027] When an abnormal situation occurs, such as the BMS module working abnormally, or the total voltage, total current, temperature, etc. of the battery pack are far beyond the normal reasonable range, the MCU module will force the main switch K1 to be disconnected to protect the safety of the battery pack;

[0028] At this time, the MCU module no longer outputs the AC control signal to the AC module, so the auxiliary switch K2 is disconnected, the control signal of the BMS cannot reach the control port of the main switch K1, and the main switch K1 is disconnected;

[0029] When the MCU module also fails, such as the MCU power circuit fails, or the crystal oscillator fails to oscillate, or the MCU itself is damaged, the MCU program runs abnormally, and the MCU cannot output a valid AC control signal. Then the auxiliary switch K2 will naturally be disconnected, and the main switch K1 will also be disconnected, thereby achieving the purpose of disconnecting the main circuit.

[0030] Among them, when MCU_MOS_PWM outputs high level or low level, the signal is isolated by the C44 capacitor and cannot be transmitted to the back end, so that Q32 gets PIN1 at a low level, Q32 cannot be turned on, and high impedance is generated between PIN3 / 2;

[0031] Due to the pull-up resistor R115, the Q32 PIN3 is in a high level signal, which controls Q35 / Q34 to be turned on, causing Q34 / Q35 PIN2 / 3 to present low impedance;

[0032] If the discharge control signal DSG and the charge control signal CHG are output at a low level, they will remain at a low level, and the control output MOS module cannot work, so that the system cannot supply power to the outside;

[0033] If the discharge control signal DSG and the charge control signal CHG are output at a high level, due to the low impedance of Q34 / Q35, the charge and discharge control signals DSG and CHG are still at a low level, and the control output MOS module cannot work, so that the system cannot supply power to the outside.

[0034] The MCU module is also provided with a current detection circuit and a fuse blowing control circuit. When the current detection circuit detects that the load exceeds the rated maximum value, the fuse blowing control circuit will be activated to blow.

[0035] The current detection circuit includes: a current detection amplifier, PIN1 of the current detection amplifier is connected to the current of the sampling circuit of the MCU module, PIN2 of the current detection amplifier is grounded, PIN3 of the current detection amplifier is connected to the SRP of the circuit, PIN4 of the current detection amplifier is connected to the SRN of the circuit, R151, R152, R156 and R159 are connected between SRP and SRN; PIN5 of the current detection amplifier is connected to VDD (3.3V).

[0036] INA180A1ID is a current detection amplifier with 20x amplification; R151 / 152 / 156 / 159 between SRP / SRN is the resistance for sampling bus current, the voltage across SRP / SRN = R*I; the resistance is known = 1.25mR, MCU_ADC_I = 1.25*I*20 times;

[0037] After the ADC voltage is collected inside the MCU module pin, the current value is inferred by reverse calculation; if the load exceeds the rated maximum value, the fuse is automatically blown to achieve system protection;

[0038] The fuse blowing control circuit includes: one end of a resistor R52 connected to the MCU fuse, the other end of the resistor R52 is connected to a resistor R54 and PIN1 of a transistor Q15, the other end of the resistor R54 is grounded, PIN2 of the transistor Q15 is grounded, PIN3 of the transistor Q15 is connected to a resistor R42, the other end of the resistor R42 is connected to PIN1 of a switch MOS tube Q18, a voltage regulator diode D2 and a resistor R39, the resistor R39 is connected to the voltage regulator diode D2 and then to PIN3 of the switch MOS tube Q18 and to a fuse F3, the other end of the fuse F3 is connected to a thyristor bat16; PIN3 of the switch MOS tube Q18 is connected to a resistor R44 and a special fuse for the battery pack.

[0039] Among them, the resistor R52 is the base protection resistor of the transistor Q15, and the resistor R54 is the ground protection resistor of the transistor Q15. When static, the base level of the transistor is kept at a low potential, turning off the transistor.

[0040] The resistor R42 and the resistor R39 are gate voltage divider resistors of the switch MOS tube Q18, and they are combined with the voltage stabilizing diode D2 to protect the gate-source voltage difference of the switch MOS tube Q18 from exceeding the rated value; the switch MOS tube Q18 controls the current on and off of the loop.

[0041] Resistor R44 is the grounding resistor of the loop, which provides a release loop to the ground and does not accumulate charge.

[0042] Fuse F3 protects the MOS tube Q18 at the back, and protects the switch MOS tube Q18 at the back.

[0043] When MCU_FUSE outputs a high level, Q18 PIN3 / PIN2 is turned on, thereby supplying power to PIN3 of the battery pack's dedicated fuse F2, causing fuse PIN1 / PIN2 to blow, thereby achieving system protection.

[0044] The embodiments disclosed in this utility model are preferred embodiments, but are not limited to them. Ordinary technicians in this field can easily understand the spirit of this utility model based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of this utility model, they are all within the protection scope of this utility model.

Claims

1. A battery protection circuit for monitoring battery control circuit faults, comprising: The BMS module and the MCU module are arranged in parallel at both ends of the battery, and a main switch K1 is connected in series between the battery and the charger. It is characterized in that the BMS module is connected to the main switch K1 through the auxiliary switch K2, and the MCU module is connected to the auxiliary switch K2 through the AC module.

2. The battery protection circuit according to claim 1, characterized in that: The MCU module includes: an input end and a capacitor C44, the capacitor C44 is connected to a diode D6, the diode D6 is connected to a capacitor C45 and an input resistor R112, the input resistor R112 is connected to a resistor R113 and PIN1 of a transistor Q32, PIN3 of the transistor Q32 is connected to a discharge control signal DSG through a transistor Q34, and is also connected to VDD through a resistor R115, and PIN3 of the transistor Q32 is connected to a charge control signal CHG through a transistor Q35.

3. The battery protection circuit according to claim 1, characterized in that: The MCU module is also provided with a current detection circuit and a fuse blowing control circuit. When the current detection circuit detects that the load exceeds the rated maximum value, the fuse blowing control circuit will be activated to blow.

4. The battery protection circuit according to claim 3, characterized in that: The current detection circuit includes: a current detection amplifier, PIN1 of the current detection amplifier is connected to the ADC current of the MCU module, PIN2 of the current detection amplifier is grounded, PIN3 of the current detection amplifier is connected to the SRP of the circuit, PIN4 of the current detection amplifier is connected to the SRN of the circuit, R151, R152, R156 and R159 are connected between SRP and SRN; PIN5 of the current detection amplifier is connected to VDD.

5. The battery protection circuit according to claim 3, characterized in that: The fuse blowing control circuit includes: one end of a resistor R52 connected to the MCU fuse, the other end of the resistor R52 is connected to a resistor R54 and PIN1 of a transistor Q15, the other end of the resistor R54 is grounded, the PIN2 of the transistor Q15 is grounded, the PIN3 of the transistor Q15 is connected to a resistor R42, the other end of the resistor R42 is connected to PIN1 of a switch MOS tube Q18, a voltage regulator diode D2 and a resistor R39, the resistor R39 is connected to the voltage regulator diode D2 and then connected to PIN3 of the switch MOS tube Q18 and a fuse F3, the other end of the fuse F3 is connected to a thyristor bat16; the PIN3 of the switch MOS tube Q18 is connected to a resistor R44 and a special fuse for a battery pack.

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