Rechargeable battery management system

Abstract

The utility model relates to a rechargeable battery management system, which comprises resistors R1, R2, R3, R10 and R11, a voltage division circuit, capacitors C1, C6 and C8, power supply chips U1 and U2 and an external battery V18650, one end of the resistor R1 is connected with the DDVDD, and the other end of the resistor R1 is connected with a No.6 pin CHGB of the power supply chip U2; one end of the resistor R2 is connected with the GND, and the other end of the resistor R2 is connected with the fourth pin PWM of the power supply chip U2; the voltage division circuit is electrically connected with an external battery V18650, a No.3 output pin OUT of the power supply chip U2, a battery voltage monitoring GPIO (General Purpose Input / Output) port Battery18650ADC of the MCU, a matched battery voltage monitoring GPIO port Battery18650ADC of the MCU and GND (Ground) respectively; the device is reasonable in design, compact in structure and convenient to use.

Description

Technical Field

[0001] The utility model relates to a rechargeable battery management system. Background Art

[0002] The primary function of an external rechargeable battery in a smart meter is to provide a backup power solution, ensuring critical smart meter functions remain operational during an AC grid outage. Specific functions include: 1) Clock information preservation. During a grid outage, the battery can continue to power the meter's internal real-time clock, ensuring clock accuracy and continuity. This is particularly important for smart meters that implement time-of-use pricing. 2) Data preservation. The battery ensures that electricity usage data stored within the meter, such as total power consumption, real-time power consumption, and rate period data, is not lost during a power outage. This data must be accurately uploaded to the power company's management system after power is restored. 3) Communication maintenance. In some designs, an external battery may provide temporary power during a grid outage, enabling the smart meter to report critical status information or upload data via communication modules such as Wi-Fi, GPRS, 4G, NB-IoT, EMTC, LoRa, Zigbee, RF, and PLC carriers. This is crucial for remote meter reading and fault monitoring. 4) Prepaid energy meter functionality maintenance. For prepaid energy meters, external batteries allow the meter to maintain basic functions, such as remaining power display and overdue bill warnings, when the main power supply is disconnected, until power is restored or the user recharges. 5) Emergency operation. In extreme cases, the battery may also provide the meter with short-term emergency operation capabilities, such as performing necessary system inspections and maintenance procedures during a grid failure. In summary, the external rechargeable battery of a smart meter plays a vital role, not only enhancing the stability and reliability of the meter under abnormal power supply conditions, but also ensuring the continuity of power service and data security.

[0003] Therefore, it is proposed to take measures to prevent lithium-ion batteries from overcharging and over-discharging through the use of a battery management system (BMS) and a lithium-ion battery protection chip. The BMS continuously monitors the voltage of the external battery and sets voltage thresholds. When the battery cell voltage reaches the preset maximum charge termination voltage (overcharge protection threshold), the BMS immediately disconnects the charging circuit to prevent overcharging. Similarly, when it detects that the external battery voltage has dropped to the minimum discharge termination voltage (over-discharge protection threshold), the lithium-ion protection chip stops the battery cell from discharging to prevent over-discharge. At the same time, the charging current is controlled to prevent it from exceeding a safety threshold to prevent excessive current from causing overheating or damage to the battery.

[0004] Since the stable power supply cycle of the power supply system in some overseas regions is unpredictable, it is necessary to ensure that the external rechargeable battery has a longer service life and a higher number of cycles. In order to achieve the above technical points, this application believes that a reliable rechargeable battery management system should be added to the hardware circuit design for protection. Utility Model Content

[0005] The technical problem to be solved by the present invention is generally to provide a rechargeable battery management system.

[0006] In order to solve the above problems, the technical solution adopted by the present invention is:

[0007] A rechargeable battery management system includes resistors R1, R2, R3, R10, R11, a voltage divider circuit, capacitors C1, C6, C8, power chips U1, U2 and an external battery V18650;

[0008] One end of resistor R1 is connected to D_DVDD, and the other end is connected to pin 6 CHGB of power chip U2;

[0009] One end of resistor R2 is connected to GND, and the other end is connected to pin 4 PWM of power chip U2;

[0010] The voltage divider circuit is electrically connected to the external battery V18650, the output pin OUT3 of the power chip U2, the MCU battery voltage monitoring GPIO port Battery_18650_ADC, the battery voltage monitoring GPIO port Battery_18650_ADC of the supporting MCU, and GND.

[0011] Resistor R11 is connected in parallel between the external battery V18650 and pin 1 PCKP of the power chip U1;

[0012] Capacitors C1 and C6 are connected between the output pin 3 OUT and GND of the external battery V18650, i.e. the power chip U2;

[0013] Capacitor C3 is connected in parallel across resistor R10, that is, between Battery_18650_ADC and GND;

[0014] Capacitor C8 is connected in parallel across resistor R2; capacitor C10 is connected between pin 6 BYPS and pin BGND of power chip U1;

[0015] The PWM pin 4 of the power chip U2 is connected to the PWM pin 20 of the MCU;

[0016] Pin 6 CHGB of the power chip U2 is connected to pin 41 PWM of the MCU.

[0017] Further, the voltage dividing circuit provides a detection signal for the voltage detection pin of the MCU;

[0018] The voltage dividing circuit comprises resistors R3 and R10;

[0019] One end of the resistor R3 is connected to the external battery V18650 and the No. 3 output pin OUT of the power supply chip U2, and the other end is connected to the battery voltage monitoring GPIO port Battery_18650_ADC of the MCU;

[0020] The resistor R10 is connected between the battery voltage monitoring GPIO port Battery_18650_ADC and the GND of the matched MCU.

[0021] Further, the system further comprises a capacitor C2 for providing an initial state for the high-impedance output pin;

[0022] The capacitor C2 is connected between the GND and the No. 6 pin CHGB of the power management chip U2.

[0023] Further, the system further comprises a decoupling capacitor; the decoupling capacitor comprises capacitors C4 and C5;

[0024] The capacitors C4 and C5 are connected in parallel between the No. 5 pin IN of the power supply chip U2 and the GND;

[0025] The No. 5 pin IN of the power supply chip U2 is an input voltage B+5V network;

[0026] The capacitors C4 and C5 are both decoupling capacitors in the B+5V network of the power supply input pin of the power supply chip U2;

[0027] The power supply chip U2 has a mode for charging the lithium ion battery.

[0028] Further, the mode state of charging the lithium ion battery comprises a pre-charge mode state, a constant-current mode state or a constant-voltage mode state;

[0029] When in the pre-charge mode state,

[0030] When the battery voltage is less than the pre-charge constant-charge transition rising threshold Vpchg, the power supply chip U2 pre-charges the external battery V18650;

[0031] When in the constant-current mode state, the charging current is determined by the duty cycle of the PWM signal of the MCU;

[0032] When in the constant-voltage mode state, the No. 3 output pin OUT of the power supply chip U2 is in a feedback battery voltage stabilizing state;

[0033] In the power chip U2, the IN pin 5 receives voltage and current from the B+5V network, the PWM pin 4 receives the pulse width modulation signal output by the MCU to control the output current, and the CHGB pin 6 is in a low-impedance state when the output voltage difference is positive.

[0034] When the battery voltage of the external battery V18650 reaches the upper limit, the power chip U2 is switched to high-impedance mode, indicating that the charging process has ended.

[0035] The discharge process is voltage-controlled by the power chip U1. The power chip U1 presets the maximum detection voltage of 4.3V and the minimum voltage of 2.8V. When the voltage of the external battery V18650 is detected to be higher than 4.3V or lower than 2.8V, the GND connected to the PCKN pin No. 1 of the power chip U1 and the battery BGND connected to BATN are disconnected.

[0036] This utility model is safe, reliable and easy to use; it has a simple circuit, low cost, high sensitivity, strong adaptability and practicality, and can detect the battery voltage and charging status through GPIO to achieve controllable charging current. When the battery voltage is too low due to long-term use, the battery power supply is actively cut off to protect and extend the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a circuit diagram of the utility model.

[0038] Figure 2 This is a partial circuit diagram of pin 20 of the MCU of the present invention.

[0039] Figure 3 This is a partial circuit diagram of pin 41 of the MCU of the present invention.

[0040] Figure 4 This is a partial circuit diagram of pin 68 of the MCU of the present invention.

[0041] Figure 5 This is a schematic diagram of the preferred MCU circuit of the present utility model. DETAILED DESCRIPTION

[0042] Example 1, as Figure 1-5 The rechargeable battery management system includes resistors R1, R2, R3, R10, R11, capacitors C1, C2, C3, C4, C5, C6, C8, C10, power chips U1, U2 and an external battery V18650. Power chip U1 is a lithium battery protection chip; power chip U2 is a charging power management chip;

[0043] like Figure 5It is the preferred main MCU diagram, the clarity of the drawing does not affect the scope of protection, and its presence or absence does not affect the scope of protection of the utility model.

[0044] One end of resistor R1 is connected to D_DVDD, and the other end is connected to pin 6 CHGB of power chip U2;

[0045] One end of resistor R2 is connected to GND, and the other end is connected to pin 4 PWM of power chip U2;

[0046] One end of resistor R3 is connected to the external battery V18650 and the output pin 3 OUT of the power chip U2, and the other end is connected to the MCU battery voltage monitoring GPIO port Battery_18650_ADC;

[0047] Resistor R10 is connected between the MCU battery voltage monitoring GPIO port Battery_18650_ADC and GND;

[0048] Resistor R11 is connected in parallel between the external battery V18650 and pin 1 PCKP of the power chip U1;

[0049] Capacitors C1 and C6 are connected between the output pin 3 OUT of the external battery V18650 (power chip U2) and GND; capacitor C2 is connected between GND and pin 6 CHGB of the power management chip U2;

[0050] Capacitor C3 is connected in parallel across resistor R10, that is, between Battery_18650_ADC and GND;

[0051] Capacitors C4 and C5 are connected in parallel between pin 5 IN and GND of the power chip U2; pin 5 IN of the power chip U2 is the input voltage B+5V network;

[0052] Capacitor C8 is connected in parallel across resistor R2; capacitor C10 is connected between pin 6 BYPS and pin BGND of power chip U1.

[0053] Resistors R3 and R10 form a voltage divider circuit to provide a detection signal for the MCU voltage detection pin; capacitor C2 is designed to provide an initial state for the high-impedance output pin; capacitors C4 and C5 are both decoupling capacitors in the power input pin B+5V network of the chip SY6978; the power chip U2 SY6978 can charge the lithium-ion battery through pre-charge, constant current (CC) mode or constant voltage (CV) mode.

[0054] When the battery voltage is less than Vpchg (pre-charge constant charge transition rising threshold), SY6978 pre-charges the battery. This function can revitalize deeply discharged batteries and protect battery life. The internally determined pre-charge rate is 15% of the constant charge current.

[0055] The constant-current CC mode charging current is determined by the PWM signal duty cycle. The CC current can be calculated using the following formula: Icc = 500 × PWM signal duty cycle (mA). A PWM signal frequency range of 20kHz to 200kHz is acceptable, and the PWM signal frequency increases inversely with the output current ripple.

[0056] When the battery voltage approaches the battery regulation voltage threshold and enters the regulation phase, the battery regulation status will be fed back through the OUT pin to monitor the battery voltage between the OUT and GND pins. The power supply chip U2 inputs voltage and current from the B+5V network through the IN pin 5. The PWM pin receives the pulse width modulation signal output by the MCU to control the output current. The CHGB pin is in a low-impedance state when the output voltage difference is positive, and the MCU can detect that it is in the charging state. At the end of the regulation charging phase, that is, when the battery voltage reaches the upper limit, the SY6978 chip automatically switches to high-impedance mode, indicating that the charging process has ended. In addition, to ensure that the PWM pulse width modulation signal maintains a good waveform at the chip receiving end, an RC filter circuit composed of resistor R2 and capacitor C8 is connected to effectively prevent distortion of the PWM high-frequency signal due to interference and crosstalk noise.

[0057] The discharge process is voltage-controlled by the lithium-ion battery protection chip. The SGM41100A-430O05 presets a maximum detection voltage of 4.3V and a minimum voltage of 2.8V. When the detection voltage of V18650 exceeds 4.3V or is lower than 2.8V, the GND connected to PCKN and the battery BGND connected to BATN will be disconnected. At this time, the battery is forcibly disconnected from the power supply circuit to prevent over-discharge of the battery.

[0058] The utility model can control the battery management chip through the MCU GPIO port to adjust the charging efficiency, effectively limiting the charging and discharging voltage of the external battery. If the battery voltage reaches the set upper and lower limit thresholds, the battery management chip directly cuts off the power supply, thereby extending the service life of the external battery.

[0059] Example 2: Based on Example 1, this system primarily uses the Silergy SY6987A linear DC charging management chip to control the charging process. It has three preset modes: constant current, constant voltage, and pre-charge. The smart meter MCU outputs a PWM signal to adjust the output current, which can reach up to 500mA. The charging indication signal is output to the MCU via an open-drain status pin. When the battery voltage approaches the threshold, the system enters the voltage regulation phase, reducing the charging current. Even after the battery voltage reaches or exceeds the set voltage, the system continues to monitor the battery voltage. When the battery voltage drops below the threshold voltage due to hysteresis, the charging current resumes. The SGM41100 lithium battery protection chip controls the discharge process. When the battery voltage is detected to have dropped to within the range of the set threshold ± the hysteresis amplitude, the system cuts off the battery power supply to ensure that the battery voltage does not drop to the damaged voltage range.

[0060] The present invention is fully described for the purpose of clearer disclosure, and the prior art will not be listed one by one.

[0061] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may be modified or some of the technical features thereof may be replaced with equivalents. It is obvious for those skilled in the art to combine multiple technical solutions of the present invention. However, these modifications or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any technical content not fully described in this utility model is generally known technology.

Claims

1. A rechargeable battery management system, characterized in that: Including resistors R1, R2, R3, R10, R11, voltage divider circuit, capacitors C1, C6, C8, power chips U1, U2 and external battery V18650; One end of resistor R1 is connected to D_DVDD, and the other end is connected to pin 6 CHGB of power chip U2; One end of resistor R2 is connected to GND, and the other end is connected to pin 4 PWM of power chip U2; The voltage divider circuit is electrically connected to the external battery V18650, the output pin OUT3 of the power chip U2, the MCU battery voltage monitoring GPIO port Battery_18650_ADC, the battery voltage monitoring GPIO port Battery_18650_ADC of the supporting MCU, and GND. Resistor R11 is connected in parallel between the external battery V18650 and pin 1 PCKP of the power chip U1; Capacitors C1 and C6 are connected between the output pin 3 OUT and GND of the external battery V18650, i.e. the power chip U2; Capacitor C3 is connected in parallel across resistor R10, that is, between Battery_18650_ADC and GND; Capacitor C8 is connected in parallel across resistor R2; capacitor C10 is connected between pin 6 BYPS and pin BGND of power chip U1; The PWM pin 4 of the power chip U2 is connected to the PWM pin 20 of the MCU; Pin 6 CHGB of the power chip U2 is connected to pin 41 PWM of the MCU.

2. The rechargeable battery management system according to claim 1, wherein: The voltage divider circuit provides a detection signal to the MCU voltage detection pin; The voltage divider circuit includes resistors R3 and R10; One end of resistor R3 is connected to the external battery V18650 and the output pin 3 OUT of the power chip U2, and the other end is connected to the MCU battery voltage monitoring GPIO port Battery_18650_ADC; Resistor R10 is connected between the battery voltage monitoring GPIO port Battery_18650_ADC of the supporting MCU and GND.

3. The rechargeable battery management system according to claim 1, wherein: The system also includes capacitor C2, which provides the initial state for the high-impedance output pin; Capacitor C2 is connected between GND and pin 6 CHGB of the power management chip U2.

4. The rechargeable battery management system according to claim 1, characterized in that: The system also includes decoupling capacitors; the decoupling capacitors include capacitors C4 and C5; Capacitors C4 and C5 are connected in parallel between pin 5 IN and GND of the power chip U2; Pin 5 IN of the power chip U2 is the input voltage B+5V network; Capacitors C4 and C5 are both decoupling capacitors in the power input pin B+5V network of the power chip U2; The power chip U2 has a mode for charging lithium-ion batteries.

5. The rechargeable battery management system according to claim 1, characterized in that: The charging mode of the lithium-ion battery includes a pre-charge mode, a constant current mode or a constant voltage mode; When in precharge mode, When the battery voltage is lower than the pre-charge / constant charge transition rising threshold Vpchg, the power chip U2 pre-charges the external battery V18650; When in constant current mode, the charging current is determined by the duty cycle of the MCU's PWM signal; When in constant voltage mode, the output pin OUT of the power chip U2 is in the feedback battery voltage regulation state; In the power chip U2, the IN pin 5 receives voltage and current from the B+5V network, the PWM pin 4 receives the pulse width modulation signal output by the MCU to control the output current, and the CHGB pin 6 is in a low-impedance state when the output voltage difference is positive. When the battery voltage of the external battery V18650 reaches the upper limit, the power chip U2 is switched to high-impedance mode, indicating that the charging process has ended.

6. The rechargeable battery management system according to claim 5, characterized in that: The discharge process is voltage-controlled by the power chip U1. The power chip U1 presets the maximum detection voltage of 4.3V and the minimum voltage of 2.8V. When the voltage of the external battery V18650 is detected to be higher than 4.3V or lower than 2.8V, the GND connected to the PCKN pin No. 1 of the power chip U1 and the battery BGND connected to BATN are disconnected.

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