A mine-used battery low static current discharge protection circuit with self-locking function

Abstract

The application discloses a mine battery low static current discharge protection circuit with a self-locking function, comprising a detection and collection unit, an under-voltage locking unit, an over-current locking unit, a control unit, a battery start-stop unit and a low-power consumption control unit; the detection and collection unit detects the discharge current of a storage battery group, detects the voltage of the storage battery group and provides a set threshold value for the under-voltage locking unit and the over-current locking unit; the under-voltage locking unit and the over-current locking unit respectively compare the set threshold value with the detected storage battery voltage signal value and output a protection signal to the control unit; the control unit controls the main loop on-off to realize protection; the under-voltage locking unit and the over-current locking unit are used to maintain the protection state; meanwhile, the low-power consumption control unit is used to reduce the static current. The application improves the stable reliability of protection, reduces the self-discharge current of the storage battery group after protection, prolongs the storage time of the storage battery group after protection and improves the convenience of equipment use.

Description

Technical Field

[0001] This invention belongs to the field of discharge protection circuit technology, specifically relating to a low static current discharge protection circuit for mining batteries with a self-locking function. Background Technology

[0002] With the gradual advancement of intelligent coal mining, an increasing number of monitoring and execution devices are being deployed underground. In accordance with national requirements for coal mine safety, and to effectively ensure safety, most mining monitoring and control equipment needs to monitor hazardous factors in real time and analyze the data based on established models. This enables timely, accurate, and reliable real-time control of safety facilities, achieving intelligent and smart operation. This necessitates that mining equipment operate continuously around the clock to improve disaster response efficiency, ensure safety, and simultaneously reduce manpower while increasing efficiency.

[0003] Due to the nature of the industry, underground power supply in coal mines is not very stable, making it impossible to meet the 24 / 7 power supply requirements of equipment. Therefore, a backup power source, i.e., rechargeable battery banks, is needed to continue power supply to equipment during power outages. However, improper use of battery banks, especially over-discharge, can cause permanent damage. At best, this reduces battery capacity and shortens discharge time after power failure, making it impossible to provide uninterrupted power to mining equipment around the clock; at worst, it can cause the battery bank to become unusable or explode, posing serious safety hazards. Therefore, to ensure working time after power failure, extend the lifespan of battery banks, and eliminate the safety hazards of battery bank explosions, strict protection against battery bank discharge is necessary in the product design.

[0004] There are four common methods for battery pack discharge protection: automatic protection by electromagnetic relay, automatic protection by field-effect transistor, automatic protection by the built-in protection board of lithium-ion battery pack, and manual mechanical disconnection of the power supply circuit.

[0005] Electromagnetic relay automatic protection: Its advantage is thorough protection. There is no leakage current after disconnection, providing good protection for the battery pack. The disadvantage is that it reduces the battery pack's discharge time. The main reason is that when the battery pack is not protected, it needs to keep the relay conducting. Since the relay operates on an electromagnetic principle, it consumes a lot of power. Therefore, in addition to the normal load current, a portion of the current consumed during battery discharge needs to be diverted to maintain relay conduction, thus reducing the battery pack's discharge time.

[0006] Automatic protection for MOSFETs (Field-Effect Transistors): The advantage is that it ensures the battery pack's discharge time; the disadvantage is poor stability and reliability. Repeated jumps occur at the protection threshold. The main reason is that after undervoltage protection is activated, the load current drops rapidly. Due to the movement of electrons inside the battery pack, the battery voltage rises back to the protection threshold, triggering the protection. After release, the load is automatically reconnected, the voltage drops again, and protection is activated again, repeating this cycle. Similarly, after overcurrent protection is activated, the load current also drops rapidly. When it falls below the overcurrent protection threshold, protection is activated. After release, the load is automatically reconnected, the current rises again, and protection is activated again, repeating this cycle. Because of the inter-electrode capacitance of the MOSFET and the parasitic capacitance of the circuit board, in most scenarios, the above two processes do not occur transiently in actual operation, but directly reach a steady state, causing the MOSFET to continuously operate in an amplifying and conducting state, resulting in a certain voltage drop. Combined with the constant load current in the circuit, the MOSFET experiences significant power consumption, exceeding the specified value and causing damage. Furthermore, frequent switching also damages the load.

[0007] Lithium-ion battery packs with built-in protection boards offer the advantage of long discharge time, primarily due to the low undervoltage protection threshold. However, a disadvantage is the short safe storage time after undervoltage protection. This is mainly due to two factors: firstly, the low undervoltage protection threshold, coupled with the fact that most built-in protection boards are based on dedicated chips that cannot be configured, results in insufficient remaining capacity after protection; secondly, the protection board and battery pack are an integrated unit, maintaining a constant electrical connection. Factors such as leakage current cause continuous self-discharge of the battery pack, and the low remaining capacity accelerates over-discharge, reducing safe storage time.

[0008] Manual mechanical power supply circuit disconnection protection: Advantages include thorough protection and simple circuitry. Disadvantages include the need for manual intervention, inability to achieve automatic undervoltage and overcurrent protection, and inability to reduce manpower and increase efficiency.

[0009] Based on the analysis of the advantages and disadvantages of the above four protection methods, it was found that, except for the field-effect transistor automatic protection method, the other three protection methods could not be perfected due to inherent reasons. Therefore, this invention adopts the field-effect transistor automatic protection method and improves it to address its shortcomings of poor stability and reliability, providing a stable and reliable low static current discharge protection circuit for mining batteries with a self-locking function. Summary of the Invention

[0010] This invention addresses the aforementioned problems and overcomes the shortcomings of existing technologies by providing a low static current discharge protection circuit for mining batteries with a self-locking function. To overcome the drawbacks of conventional protection methods, this invention adds an undervoltage lockout unit and an overcurrent lockout unit to improve the stability and reliability of the protection; it employs a low-power control unit to reduce the self-discharge current of the battery pack after protection, extending the storage time of the battery pack after protection; and it also adds a battery start-stop unit to improve the ease of use of the equipment.

[0011] To achieve the above objectives, the present invention adopts the following technical solution.

[0012] The present invention provides a low static current discharge protection circuit for mining batteries with self-locking function, including a detection and acquisition unit, an undervoltage lockout unit, an overcurrent lockout unit, a control unit, a battery start-stop unit, and a low power consumption control unit;

[0013] The detection and acquisition unit is used to detect the battery pack discharge current, detect the battery pack voltage, and provide setting thresholds for the undervoltage lockout unit and the overcurrent lockout unit.

[0014] The undervoltage lockout unit is used to feed back the protection control output signal to the detection and acquisition unit, increase the comparison depth, improve the protection recovery value, and avoid the jitter caused by voltage rebound after the load is disconnected.

[0015] The overcurrent locking unit is used to feed back the protection control output signal to the detection and acquisition unit, reduce the set threshold, increase the comparison depth, extend the protection duration, and avoid the jitter caused by the current reduction after the load is disconnected.

[0016] The control unit is used to control the on / off state of the main circuit.

[0017] The battery start / stop unit is used to directly start and stop the battery pack and to trigger the temporary conduction of the control unit.

[0018] The low-power control unit is used to control the power supply mode of each device in the protected circuit, reduce the static operating current of the protected circuit, and thus extend the safe storage time of the battery pack.

[0019] The detection and acquisition unit detects the battery pack discharge current and voltage, and provides set thresholds for the undervoltage lockout unit and overcurrent lockout unit. The undervoltage lockout unit and overcurrent lockout unit compare the set thresholds with the detected battery pack voltage signal value, and output protection signals to the control unit. The control unit controls the main circuit to switch on and off to achieve protection. The undervoltage lockout unit and overcurrent lockout unit are used to maintain the protection state. At the same time, the low-power control unit is used to reduce the static current.

[0020] Furthermore, the detection and acquisition unit includes a threshold setting unit, a current detection unit, and a voltage detection unit. The threshold setting unit is used to provide a set threshold for the undervoltage lockout unit and the overcurrent lockout unit. The current detection unit is used to detect the battery pack discharge current, and the voltage detection unit is used to detect the battery pack voltage.

[0021] Furthermore, the current detection unit includes a current sensing resistor R1, a high-side current sensing amplifier U1, a gain setting resistor R7, and a filter capacitor C3. The current sensing resistor R1 is connected between pins 3 and 4 of the high-side current sensing amplifier U1, and pin 1 of the high-side current sensing amplifier U1 is connected to the gain setting resistor R7. The filter capacitor C3 is connected in parallel across the gain setting resistor R7. The current detection unit converts the load current into a high-side low voltage through the current sensing resistor R1, and then amplifies it through the high-side current sensing amplifier U1 before connecting it to the input terminal of the overcurrent lockout unit.

[0022] Furthermore, the threshold setting unit includes a current-limiting resistor R2 and a voltage reference chip U3. The current-limiting resistor R2 is connected to the voltage reference chip U3. The threshold setting unit provides a setting threshold Vset for the undervoltage lockout unit and the overcurrent lockout unit, respectively. The connection terminals of the current-limiting resistor R2 and the voltage reference chip U3 of the threshold setting unit are connected to the input terminals of the undervoltage lockout unit and the overcurrent lockout unit, respectively.

[0023] Furthermore, the voltage detection unit includes voltage divider resistors R5 and R9, which are connected together to the undervoltage lockout unit. The voltage detection unit divides the output voltage of the battery pack through the voltage divider resistors R5 and R9 and then connects it to the input terminal of the undervoltage lockout unit.

[0024] Furthermore, the undervoltage lockout unit includes a comparator U2A, diodes D1 and D2, and a resistor R6. The output pin 1 of comparator U2A is connected to the cathode of diode D2, and the anode of diode D1 is connected to resistor R6. Diode D1 and resistor R6 are connected between the output pin 1 and the positive input pin 3 of comparator U2A. The anode of diode D1 is connected to the output pin 1 of comparator U2A, and the anode of diode D2 is connected to the control unit. The positive input pin 3 of comparator U2A is connected to the voltage divider resistors R5 and R9 of the voltage detection unit, and the negative input pin 2 of comparator U2A is connected to the current limiting resistor R2 and the voltage reference chip U3 of the threshold setting unit. Diode D1 and resistor R6 are feedback lockout devices for the undervoltage lockout unit; diode D2 is an isolation device for the undervoltage lockout unit, providing overcurrent protection.

[0025] Furthermore, the overcurrent lockout unit includes a comparator U2B, a capacitor C4, and a diode D3. The output pin 7 of the comparator U2B is connected to the cathode of the diode D3. The capacitor C4 is connected between the output pin 7 of the comparator U2B and the positive input pin 5. The anode of the diode D3 is connected to the control unit. The negative input pin 6 of the comparator U2B is connected to pin 1 of the high-side current sensing amplifier U1 of the current detection unit. The positive input pin 5 of the comparator U2B is connected to the current limiting resistor R2 and the voltage reference chip U3 of the threshold setting unit. The capacitor C4 is the feedback lockout device of the overcurrent lockout unit. The diode D3 is the isolation device of the overcurrent lockout unit, and the diode D3 plays a role in isolating undervoltage protection.

[0026] Furthermore, the control unit includes a first-level control circuit and a second-level control circuit. The first-level control circuit controls the second-level control circuit by switching on and off, and the second-level control circuit controls the on and off of the main circuit. The first-level control circuit includes a pull-up resistor R3, a clamping resistor R11, and a transistor Q2. The pull-up resistor R3 and the clamping resistor R11 are connected and are both connected to the base of the transistor Q2. The pull-up resistor R3, the clamping resistor R11, and the base of the transistor Q2 are all connected to the anode of the diode D2 of the undervoltage lockout unit and the anode of the diode D3 of the overcurrent lockout unit, respectively. The second-level control circuit includes a field-effect transistor Q1 and a clamping resistor R4. The field-effect transistor Q1 and the clamping resistor R4 are connected in parallel.

[0027] Furthermore, the battery start-stop unit includes a self-locking switch S1, an energy storage capacitor C2, a current-limiting resistor R8, and a light-emitting diode D4. The self-locking switch S1, energy storage capacitor C2, current-limiting resistor R8, and light-emitting diode D4 are connected in sequence. One end of the self-locking switch S1 is connected to the second-stage control circuit, and the two ends of the energy storage capacitor C2 are connected to the emitter and collector terminals of the transistor Q2 in the first-stage control circuit.

[0028] Furthermore, the low-power control unit consists of a second-stage control circuit, a field-effect transistor Q3, a clamping resistor R10, and a current-limiting resistor R12. Both the clamping resistor R10 and the current-limiting resistor R12 are connected to the field-effect transistor Q3. The clamping resistor R10 is connected to pin 2 of the high-side current sensing amplifier U1 of the current detection unit, the voltage reference chip U3 of the threshold setting unit, and the voltage divider resistor R9 of the voltage detection unit, respectively. The current-limiting resistor R12 is connected to the second-stage control circuit, and a capacitor C1 is connected between the current-limiting resistor R12 and the negative terminal of the battery pack.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] This invention improves the stability and reliability of protection by adding an undervoltage lockout unit and an overcurrent lockout unit; it reduces the self-discharge current of the battery pack after protection by using a low-power control unit, thus extending the storage time of the battery pack after protection; and it improves the ease of use of the equipment by adding a battery start-stop unit. Attached Figure Description

[0031] Figure 1 This is a schematic block diagram of a low static current discharge protection circuit for a mining battery with a self-locking function according to the present invention.

[0032] Figure 2 This is a circuit diagram of a low static current discharge protection circuit for a mining battery with a self-locking function according to the present invention.

[0033] Figure 3 This is a circuit diagram of the voltage detection unit of a low static current discharge protection circuit for a mining battery with a self-locking function according to the present invention.

[0034] Figure 4 This is an equivalent circuit diagram of the voltage detection unit of a low static current discharge protection circuit for a mining battery with a self-locking function according to the present invention.

[0035] Figure 5 This is an equivalent circuit diagram of the threshold setting unit of a low static current discharge protection circuit for mining batteries with self-locking function according to the present invention. Detailed Implementation

[0036] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0037] Reference Figures 1 to 5 As shown, the present invention provides a low static current discharge protection circuit for mining batteries with self-locking function, including a detection and acquisition unit, an undervoltage lockout unit, an overcurrent lockout unit, a control unit, a battery start / stop unit, and a low power consumption control unit; the detection and acquisition unit includes a threshold setting unit, a current detection unit, and a voltage detection unit. The threshold setting unit is used to provide a set threshold for the undervoltage lockout unit and the overcurrent lockout unit. The current detection unit is used to detect the discharge current of the battery pack BT1, and the voltage detection unit is used to detect the voltage of the battery pack BT1.

[0038] The undervoltage lockout unit is used to feed back the protection control output signal to the detection and acquisition unit, increase the comparison depth, improve the protection recovery value, and avoid the jitter caused by the voltage rise after the load is disconnected. The overcurrent lockout unit is used to feed back the protection control output signal to the detection and acquisition unit, reduce the set threshold, increase the comparison depth, extend the protection duration, and avoid the jitter caused by the current drop after the load is disconnected.

[0039] The control unit is used to control the on / off state of the main circuit; the battery start / stop unit is used to enable direct start and stop of the battery pack BT1 and to trigger the temporary conduction of the control unit; the low-power control unit is used to control the power supply mode of each device in the protected circuit, reduce the static operating current of the protected circuit, thereby extending the safe storage time of the battery pack BT1.

[0040] The discharge current of battery pack BT1 is detected by the current detection unit, and the voltage of battery pack BT1 is detected by the voltage detection unit. The threshold setting unit provides a set threshold for the undervoltage lockout unit and the overcurrent lockout unit. The undervoltage lockout unit and the overcurrent lockout unit compare the set threshold with the detected voltage signal value of battery pack BT1, and output the protection signal to the control unit. The control unit controls the on / off of the main circuit to achieve protection. The undervoltage lockout unit and the overcurrent lockout unit are used to maintain the protection state. At the same time, the low-power control unit is used to reduce the static current.

[0041] The current detection unit includes a current sensing resistor R1, a high-side current sensing amplifier U1, a gain setting resistor R7, and a filter capacitor C3. The current sensing resistor R1 is connected between pins 3 and 4 of the high-side current sensing amplifier U1, and pin 1 of the high-side current sensing amplifier U1 is connected to the gain setting resistor R7. The filter capacitor C3 is connected in parallel across the gain setting resistor R7. The current detection unit converts the load current into a high-side low voltage through the current sensing resistor R1, and then amplifies it through the high-side current sensing amplifier U1 before connecting it to the input terminal of the overcurrent lockout unit.

[0042] The threshold setting unit includes a current-limiting resistor R2 and a voltage reference chip U3. The current-limiting resistor R2 is connected to the voltage reference chip U3. The threshold setting unit provides a setting threshold Vset for the undervoltage lockout unit and the overcurrent lockout unit, respectively. The connection terminals of the current-limiting resistor R2 and the voltage reference chip U3 of the threshold setting unit are connected to the input terminals of the undervoltage lockout unit and the overcurrent lockout unit, respectively.

[0043] The voltage detection unit includes voltage divider resistors R5 and R9. Voltage divider resistors R5 and R9 are connected to the undervoltage lockout unit. The voltage detection unit divides the output voltage of the battery pack BT1 through voltage divider resistors R5 and R9 and then connects it to the input terminal of the undervoltage lockout unit.

[0044] Specifically, the threshold setting unit provides a setting threshold Vset for undervoltage protection and overcurrent protection and is connected to the negative input terminal of comparator U2A of the undervoltage lockout unit and the positive input terminal of comparator U2B of the overcurrent lockout unit; wherein, U3 is a voltage reference chip, and the regulated voltage value is Vset.

[0045] The voltage detection unit divides the BT1 voltage of the battery pack and connects it to the positive input terminal of the comparator U2A of the undervoltage lockout unit for comparison with Vset. Under normal operating conditions, the BT1 voltage of the battery pack is calculated using the following formula:

[0046]

[0047] The current detection unit converts the load current into a high-side low voltage through the current sensing resistor R1, then amplifies it through the high-side current sensing amplifier U1 before connecting it to the negative input of the comparator U2B in the overcurrent lockout unit for comparison with Vset. The high-side current sensing amplifier U1 is an INA168, which features a wide input common-mode voltage range and low quiescent current in a small SOT-23 package. The INA168 has a voltage range of 2.7V to 60V and a quiescent current of only 25μA, allowing the battery pack BT1 to be connected to either side with very low error. The formula for calculating the low-side proportional output voltage Vibat at the negative input of comparator U2B and the discharge circuit load current I is as follows:

[0048]

[0049] The undervoltage lockout unit includes a comparator U2A, diodes D1 and D2, and a resistor R6. The output pin 1 of comparator U2A is connected to the cathode of diode D2, and the anode of diode D1 is connected to resistor R6. Diode D1 and resistor R6 are connected between the output pin 1 and the positive input pin 3 of comparator U2A. The anode of diode D1 is connected to the output pin 1 of comparator U2A, and the anode of diode D2 is connected to the control unit. The positive input pin 3 of comparator U2A is connected to the voltage divider resistors R5 and R9 of the voltage detection unit, and the negative input pin 2 of comparator U2A is connected to the current limiting resistor R2 and the voltage reference chip U3 of the threshold setting unit. Diode D1 and resistor R6 are the feedback lockout devices of the undervoltage lockout unit; diode D2 is the isolation device of the undervoltage lockout unit, providing overcurrent protection.

[0050] Under normal operating conditions, the circuit of the voltage detection unit of battery pack BT1 is as follows: Figure 3As shown. When the down-voltage protection voltage Vdown of battery pack BT1 is lower than Vset, pin 1 of comparator U2A outputs a low level to control NPN transistor Q2 to turn off. NPN transistor Q2 then controls P-channel MOSFET Q1 to turn off, executing undervoltage protection. However, during the turn-off process of NPN transistor Q2, the voltage of battery pack BT1 will rise due to the decrease in load current. At this time, pin 1 of comparator U2A outputs an open-drain signal, which is controlled by pull-up resistor R3 to turn on NPN transistor Q2. NPN transistor Q2 then controls P-channel MOSFET Q1 to turn on, canceling the undervoltage protection. This cycle repeats, leading to unreliable protection. To ensure the reliability of protection, this invention sets diode D1 and resistor R6 as feedback locking devices for the undervoltage lockout unit. Since pin 1 of comparator U2A is low when the undervoltage protection is activated, the voltage acquisition of battery pack BT1 will change, such as... Figure 4 The diagram shown is the equivalent circuit diagram of the voltage detection unit. According to Ohm's law, the formula for calculating the battery's upward recovery voltage Vup is as follows:

[0051]

[0052] In formula (3), V D2 This is the on-state voltage drop of D2.

[0053] Calculations show that the upward recovery voltage Vup of battery pack BT1 is greater than the downward protection voltage Vdown of battery pack BT1, thus protection locking can be achieved. According to the circuit start-stop conditions, the circuit can only be started through the self-locking switch S1 when the voltage of battery pack BT1 is above Vup.

[0054] The overcurrent lockout unit includes a comparator U2B, a capacitor C4, and a diode D3. The output pin 7 of the comparator U2B is connected to the cathode of the diode D3. The capacitor C4 is connected between the output pin 7 of the comparator U2B and the positive input pin 5. The anode of the diode D3 is connected to the control unit. The negative input pin 6 of the comparator U2B is connected to pin 1 of the high-side current sensing amplifier U1 of the current detection unit. The positive input pin 5 of the comparator U2B is connected to the current limiting resistor R2 and the voltage reference chip U3 of the threshold setting unit. The capacitor C4 is the feedback lockout device of the overcurrent lockout unit. The diode D3 is the isolation device of the overcurrent lockout unit, and the diode D3 plays a role in isolating undervoltage protection.

[0055] Under normal operating conditions, when the low-side proportional output voltage Vibat is greater than Vset, pin 7 of comparator U2B outputs a low level, controlling NPN transistor Q2 to turn off. NPN transistor Q2 then controls P-channel MOSFET Q1 to turn off, executing overcurrent protection. To improve anti-interference capability, a filter capacitor C3 is connected in parallel with the amplification factor setting resistor R7 to eliminate harmonic interference generated by high-frequency loads. However, during the turn-off process of NPN transistor Q2, its impedance increases, causing the load current to decrease. When the low-side proportional output voltage Vibat is lower than Vset, pin 1 of comparator U2A outputs an open-drain signal, which, through pull-up resistor R3, controls NPN transistor Q2 to turn on. NPN transistor Q2 then controls P-channel MOSFET Q1 to turn on, canceling the overcurrent protection. This cycle repeats, leading to unreliable protection. To ensure protection reliability, this invention includes capacitor C4 as a feedback locking device for the overcurrent locking unit. Since pin 7 of comparator U2B is low when the undervoltage protection activates, the setting circuit of the threshold voltage Vset setting unit will change. The equivalent circuit of the threshold setting unit is as follows: Figure 5 As shown. During the instantaneous overcurrent protection, VIN charges capacitor C4 through current-limiting resistor R2, and Vset rises from zero; when it rises to Vibat, the overcurrent protection is canceled. The time it takes for Vset to rise from zero to Vibat is the overcurrent protection interval.

[0056] Specifically, the comparators U2A and U2B are both LM393.

[0057] The control unit employs a two-stage control circuit to control the on / off state of the main circuit, specifically including a first-stage control circuit and a second-stage control circuit. The on / off state of the first-stage control circuit controls the second-stage control circuit, which in turn controls the on / off state of the main circuit. The first-stage control circuit includes a pull-up resistor R3, a clamping resistor R11, and an NPN transistor Q2. The clamping resistor R11 ensures that the NPN transistor Q2 is statically turned off. The pull-up resistor R3 is connected to the clamping resistor R11 and both are connected to the NPN transistor Q2. The base terminal of transistor Q2 is connected; the pull-up resistor R3, the clamping resistor R11, and the base terminal of NPN transistor Q2 are all connected to the anode terminal of diode D2 in the undervoltage lockout unit and the anode terminal of diode D3 in the overcurrent lockout unit, respectively; the second-stage control circuit includes P-channel MOSFET Q1 and clamping resistor R4. The clamping resistor R4 can ensure that P-channel MOSFET Q1 is statically turned off. P-channel MOSFET Q1 and clamping resistor R4 are connected in parallel. P-channel MOSFET Q1 controls the on / off state of the main circuit.

[0058] When the protection conditions are not met, the undervoltage lockout unit and the overcurrent lockout unit output open-drain signals. VOUT supplies power to the base of the NPN transistor Q2 via the pull-up resistor R3, generating a base current I. BQ2When equation (4) is satisfied, the NPN transistor Q2 will saturate and conduct. At this time, the drain-source voltage V of the P-channel MOSFET Q1 will be... GS_Q1 Calculate according to formula (5). By selecting the values ​​of clamping resistor R4 and current-limiting resistor R8, V can be... GS_Q1 The P-channel MOSFET Q1 turns on when the current condition is greater than the current condition for Q1 to turn on.

[0059]

[0060] Where β is the amplification factor of NPN transistor Q2.

[0061]

[0062] Where VOUT is the output voltage, V D4 This is the voltage drop when the LED D4 is turned on.

[0063] When the protection condition is met, the acquisition and comparison circuit outputs a low level, the NPN transistor Q2 is turned off, and the drain-source voltage V of the P-channel MOSFET Q1 is reduced. GS_Q1 The P-channel MOSFET Q1 is turned off because the clamping resistor R4 clamps it to zero, which does not meet the turn-on condition of the P-channel MOSFET Q1.

[0064] The battery start-stop unit includes a self-locking switch S1, an energy storage capacitor C2, a current-limiting resistor R8, and an LED D4. These components are connected sequentially, with LED D4 serving as a start / stop status indicator. One end of the self-locking switch S1 is connected to the second-stage control circuit, and both ends of the energy storage capacitor C2 are connected to the emitter and collector terminals of the NPN transistor Q2 in the first-stage control circuit. The battery start-stop unit can be temporarily activated by triggering the control unit via the self-locking switch S1, regardless of whether the battery pack BT1 is undervoltage. This greatly facilitates on-site equipment debugging.

[0065] With the self-locking switch S1 open, due to the clamping effect of the current-limiting resistor R8 and the LED D4, the potentials across the energy storage capacitor C2 are equal and both zero. At this time, the self-locking switch S1 is closed and held. Due to the energy storage characteristics of the capacitor, the energy storage capacitor C2 will charge through the clamping resistor R4. At this time, V... GS_Q1Approximately equal to VIN, satisfying the conduction condition of P-channel MOSFET Q1, P-channel MOSFET Q1 conducts, the battery pack BT1 output is turned on, and power is supplied to other unit circuits to start their operation. If the detection and acquisition unit does not detect undervoltage protection or overcurrent protection conditions at this time, pins 1 and 7 of the high-side current sensing amplifier U1 will be in a floating state. The current controls the NPN transistor Q2 to conduct through the pull-up resistor R3, keeping the P-channel MOSFET Q1 continuously conducting. At the same time, the NPN transistor Q2 discharges the energy storage capacitor C2, preparing for the next start-up of the battery pack BT1; if the detection and acquisition unit detects protection conditions at this time, pins 1 and 7 of the high-side current sensing amplifier U1 will output a low level, controlling the NPN transistor Q2 and P-channel MOSFET Q1 to turn off.

[0066] When the circuit of this invention is turned on, the self-locking switch S1 is disconnected and held. The drain-source voltage V of the P-channel MOSFET Q1 is... GS_Q1 The P-channel MOSFET Q1 is turned off by clamping resistor R4 to zero. After Q1 is turned off, the power supply circuit of other units is disconnected, causing them to stop working and reducing power consumption.

[0067] The low-power control unit consists of a second-stage control circuit, a field-effect transistor (FET) Q3, a clamping resistor R10, and a current-limiting resistor R12. Both the clamping resistor R10 and the current-limiting resistor R12 are connected to the FET Q3, which is an N-channel FET. The clamping resistor R10 is connected to pin 2 of the high-side current sensing amplifier U1 of the current detection unit, the voltage reference chip U3 of the threshold setting unit, and the voltage divider resistor R9 of the voltage detection unit. The current-limiting resistor R12 is connected to the second-stage control circuit, and a capacitor C1 is connected between the current-limiting resistor R12 and the negative terminal of the battery pack. The clamping resistor R10 ensures that the N-channel FET Q3 is statically turned off.

[0068] The control circuit of P-channel MOSFET Q1 consists of clamping resistor R4, latching switch S1, energy storage capacitor C2, current limiting resistor R8, and LED D4. Energy storage capacitor C2 does not consume power in its static state. Latching switch S1 is a start / stop switch. When latching switch S1 is off, the control circuit of P-channel MOSFET Q1 is open, and this circuit does not consume power. When latching switch S1 is on and the circuit is in protection mode, NPN transistor Q2 is off. At this time, the static current of this part is the leakage current I of NPN transistor Q2 when it is off. Q2 .

[0069] The negative power supply of the control circuit for comparator U2B and NPN transistor Q2 is directly connected to the negative terminal of battery pack BT1, while the positive power supply is connected to the circuit output. After circuit protection is activated, there is no voltage at the output, causing the positive power supply to the control circuit of comparator U2B and NPN transistor Q2 to be disconnected, rendering them unable to operate. Simultaneously, because the pull-up resistor R3 is disconnected from the positive power supply, the base of NPN transistor Q2 is pulled down by clamping resistor R11, resulting in a zero potential, thus maintaining the protection state. The quiescent current in this section is the leakage current I when the P-channel MOSFET Q1 is turned off. Q1 .

[0070] The positive power supply of the detection and acquisition unit and the threshold setting unit is directly connected to the positive terminal of the battery pack BT1, while the negative power supply is connected to the negative terminal of the battery pack BT1 after being controlled by the N-channel MOSFET Q3. The N-channel MOSFET Q3 is clamped by the clamping resistor R10 and the current-limiting resistor R12. In the circuit's on state, V... GS_Q3 The calculation formula is as follows:

[0071]

[0072] By selecting the parameters of clamping resistor R10 and current-limiting resistor R12, V GS_Q3 The voltage requirement is greater than the conduction condition of the N-channel MOSFET Q3. Under operating conditions, the N-channel MOSFET Q3 is turned on. Since the circuit current of the detection and acquisition unit is in the mA range, the conduction voltage of the N-channel MOSFET Q3 is extremely low, having minimal impact on detection accuracy. After circuit protection, there is no voltage at the output terminal. At this time, V is clamped by the clamping resistor R10. GS_Q3 The clamping is set to zero, which does not meet the turn-on condition of the N-channel MOSFET Q3, causing Q3 to turn off. At this time, the quiescent current of the detection and acquisition unit and the threshold setting unit is the leakage current I when the N-channel MOSFET Q3 is turned off. Q3 .

[0073] In summary, the total static supply current I0 under battery protection mode is:

[0074] I0 = I Q1 +I Q2 +I Q3 (7)

[0075] By selecting P-channel MOSFET Q1, NPN transistor Q2, and N-channel MOSFET Q3, a static operating current in the μA range can be achieved.

[0076] This invention, based on traditional MOSFET automatic protection, employs undervoltage lockout and overcurrent lockout units to achieve undervoltage protection lockout and discharge overcurrent protection lockout, solving problems that conventional protection methods cannot address. Traditional circuits are all open-loop control; therefore, during protection execution, the detection conditions change in reverse, leading to protection deactivation and protection jitter. This invention, through the undervoltage lockout and overcurrent lockout units, feeds control signals back to the detection loop, deepening the detection conditions and achieving protection lockout. In traditional circuits, all components are directly powered by batteries. Although the operating current can be minimized through parameter selection, it's impossible to reduce the current too much to ensure operational stability and meet the minimum operating current requirements of certain components. This invention, through its low-power control unit, achieves static low-power processing. Except for the main control loop, all other components are powered by a single-ended power supply, disconnecting the power supply required for normal operation during protection, thereby reducing the static operating current. Therefore, after protection, the static operating current is only the sum of the leakage currents of the switching devices.

[0077] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

Claims

1. A low static current discharge protection circuit for mining batteries with a self-locking function, characterized in that: It includes a detection and acquisition unit, an undervoltage lockout unit, an overcurrent lockout unit, a control unit, a battery start / stop unit, and a low-power control unit; The detection and acquisition unit is used to detect the battery pack discharge current, detect the battery pack voltage, and provide setting thresholds for the undervoltage lockout unit and the overcurrent lockout unit. The undervoltage lockout unit is used to feed back the protection control output signal to the detection and acquisition unit, increase the comparison depth, improve the protection recovery value, and avoid the jitter caused by voltage rebound after the load is disconnected. The overcurrent locking unit is used to feed back the protection control output signal to the detection and acquisition unit, reduce the set threshold, increase the comparison depth, extend the protection duration, and avoid the jitter caused by the current reduction after the load is disconnected. The control unit is used to control the on / off state of the main circuit. The battery start / stop unit is used to directly start and stop the battery pack and to trigger the temporary conduction of the control unit. The low-power control unit is used to control the power supply mode of each device in the protected circuit, reduce the static operating current of the protected circuit, and thus extend the safe storage time of the battery pack. The detection and acquisition unit detects the battery pack discharge current and voltage, and provides set thresholds for the undervoltage lockout unit and overcurrent lockout unit. The undervoltage lockout unit and overcurrent lockout unit compare the set thresholds with the detected battery pack voltage signal value, and output protection signals to the control unit. The control unit controls the main circuit to switch on and off, thereby realizing protection. The undervoltage lockout unit and overcurrent lockout unit maintain the protection state. At the same time, the low-power control unit reduces the static current. The undervoltage lockout unit includes a comparator U2A, diodes D1 and D2, and a resistor R6. The output pin 1 of comparator U2A is connected to the cathode of diode D2, and the anode of diode D1 is connected to resistor R6. Diode D1 and resistor R6 are connected between the output pin 1 and the positive input pin 3 of comparator U2A. The anode of diode D1 is connected to the output pin 1 of comparator U2A, and the anode of diode D2 is connected to the control unit. The positive input pin 3 of comparator U2A is connected to the voltage divider resistors R5 and R9 of the voltage detection unit, and the negative input pin 2 of comparator U2A is connected to the current limiting resistor R2 and the voltage reference chip U3 of the threshold setting unit. Diode D1 and resistor R6 are the feedback lockout devices of the undervoltage lockout unit; diode D2 is the isolation device of the undervoltage lockout unit, providing overcurrent protection. The overcurrent lockout unit includes a comparator U2B, a capacitor C4, and a diode D3. The output pin 7 of the comparator U2B is connected to the cathode of the diode D3. The capacitor C4 is connected between the output pin 7 of the comparator U2B and the positive input pin 5. The anode of the diode D3 is connected to the control unit. The negative input pin 6 of the comparator U2B is connected to pin 1 of the high-side current sensing amplifier U1 of the current detection unit. The positive input pin 5 of the comparator U2B is connected to the current limiting resistor R2 and the voltage reference chip U3 of the threshold setting unit. The capacitor C4 is the feedback lockout device of the overcurrent lockout unit. Diode D3 is the isolation device of the overcurrent lockout unit, and diode D3 plays the role of isolation and undervoltage protection; The low-power control unit consists of a second-stage control circuit, a field-effect transistor Q3, a clamping resistor R10, and a current-limiting resistor R12. Both the clamping resistor R10 and the current-limiting resistor R12 are connected to the field-effect transistor Q3. The clamping resistor R10 is connected to the current detection unit, the threshold setting unit, and the voltage detection unit, respectively. The current-limiting resistor R12 is connected to the second-stage control circuit, and a capacitor C1 is connected between the current-limiting resistor R12 and the negative terminal of the battery pack.

2. The low static current discharge protection circuit with self-locking function for mine battery according to claim 1, characterized in that: The detection and acquisition unit includes a threshold setting unit, a current detection unit, and a voltage detection unit. The threshold setting unit is used to provide a set threshold for the undervoltage lockout unit and the overcurrent lockout unit. The current detection unit is used to detect the battery pack discharge current, and the voltage detection unit is used to detect the battery pack voltage.

3. The low static current discharge protection circuit with self-locking function for mine battery according to claim 2, characterized in that: The current detection unit includes a current sensing resistor R1, a high-side current sensing amplifier U1, a gain setting resistor R7, and a filter capacitor C3. The current sensing resistor R1 is connected between pins 3 and 4 of the high-side current sensing amplifier U1, and pin 1 of the high-side current sensing amplifier U1 is connected to the gain setting resistor R7. The filter capacitor C3 is connected in parallel across the gain setting resistor R7. The current detection unit converts the load current into a high-side low voltage through the current sensing resistor R1, and then amplifies it through the high-side current sensing amplifier U1 before connecting it to the input terminal of the overcurrent lockout unit.

4. A low static current discharge protection circuit for a mining battery with self-locking function according to claim 2, characterized in that: The threshold setting unit includes a current-limiting resistor R2 and a voltage reference chip U3. The current-limiting resistor R2 is connected to the voltage reference chip U3. The threshold setting unit provides a setting threshold Vset for the undervoltage lockout unit and the overcurrent lockout unit, respectively. The connection terminals of the current-limiting resistor R2 and the voltage reference chip U3 of the threshold setting unit are connected to the input terminals of the undervoltage lockout unit and the overcurrent lockout unit, respectively.

5. A low static current discharge protection circuit for a mining battery with a self-locking function according to claim 2, characterized in that: The voltage detection unit includes voltage divider resistors R5 and R9. Voltage divider resistors R5 and R9 are connected to the undervoltage lockout unit. The voltage detection unit divides the output voltage of the battery pack through voltage divider resistors R5 and R9 and then connects it to the input terminal of the undervoltage lockout unit.

6. A low static current discharge protection circuit for a mining battery with self-locking function according to claim 1, characterized in that: The control unit includes a first-level control circuit and a second-level control circuit. The first-level control circuit controls the second-level control circuit, and the second-level control circuit controls the main circuit. The first-level control circuit includes a pull-up resistor R3, a clamping resistor R11, and a transistor Q2. The pull-up resistor R3 and the clamping resistor R11 are connected and both are connected to the base of the transistor Q2. The pull-up resistor R3, the clamping resistor R11, and the base of the transistor Q2 are respectively connected to the undervoltage lockout unit and the overcurrent lockout unit. The second-level control circuit includes a field-effect transistor Q1 and a clamping resistor R4. The field-effect transistor Q1 and the clamping resistor R4 are connected in parallel.

7. A low static current discharge protection circuit for a mining battery with a self-locking function according to claim 6, characterized in that: The battery start / stop unit includes a self-locking switch S1, an energy storage capacitor C2, a current-limiting resistor R8, and a light-emitting diode D4. The self-locking switch S1, energy storage capacitor C2, current-limiting resistor R8, and light-emitting diode D4 are connected in sequence. One end of the self-locking switch S1 is connected to the second-stage control circuit, and the two ends of the energy storage capacitor C2 are connected to the emitter and collector terminals of the transistor Q2 in the first-stage control circuit.

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