CN108879618B - Battery protection circuit and multi-level battery protection circuit - Google Patents
Battery protection circuit and multi-level battery protection circuit Download PDFInfo
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- CN108879618B CN108879618B CN201810800306.3A CN201810800306A CN108879618B CN 108879618 B CN108879618 B CN 108879618B CN 201810800306 A CN201810800306 A CN 201810800306A CN 108879618 B CN108879618 B CN 108879618B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/18—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for batteries; for accumulators
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Abstract
The invention discloses a battery protection circuit, which comprises a battery input end connected with a battery, a circuit connecting end used for voltage input and output, a voltage comparison circuit, a first switch control circuit, a first switch tube and a first diode, wherein the first switch control circuit is used for controlling the on-off of the first switch tube; the voltage comparison circuit compares the voltage of the battery input end and the circuit connecting end to control the output of the first switch control circuit, and then controls the on-off of the first switch tube, so as to ensure that the battery is not damaged by the high voltage input by the circuit connecting end. The invention also provides a multi-level battery protection circuit, which comprises batteries of at least two specifications and battery protection circuits corresponding to the batteries one to one, wherein the output ends of the batteries are connected with the battery input ends of the battery protection circuits, the circuit connecting ends of the battery protection circuits are connected with the input ends of the load circuits, and one battery corresponds to one battery protection circuit, so that the independent protection of the batteries of various specifications is realized.
Description
Technical Field
The invention relates to the field of battery protection, in particular to a battery protection circuit and a multi-level battery protection circuit.
Background
At present, a battery protection circuit is mature and is applied to various products, such as an electric vehicle battery charger, a mobile phone charger, an electric vehicle charger, a robot battery charging pile and the like; the battery protection circuit is arranged in the charger or on the battery protection board of the product, and in the prior art, a charge and discharge protection chip or a simulated charge and discharge protection circuit is generally used for protecting the charge and discharge process of the battery, so that battery faults are avoided, such as overvoltage, overcharge, overdischarge, overcurrent, overtemperature protection and the like of the battery are realized.
The existing battery charge-discharge protection circuit comprises a battery, a charging circuit, a load circuit, an overvoltage protection circuit and an undervoltage protection circuit; the battery protection is realized by a digital logic and analog comparison circuit by mainly utilizing a digital electronic circuit and an analog electronic circuit, and the overvoltage, overcurrent, overcharge, overdischarge and overtemperature protection of the battery in the charging and discharging processes is completed; for example, referring to fig. 1, a lithium battery charging/discharging overcharge/overdischarge protection circuit includes a charging power supply circuit module, a switch circuit module, a lithium battery and a microcontroller MCU, which are connected in sequence, wherein the microcontroller MCU is connected to the switch circuit module, and the lithium battery is connected to an overvoltage/overcurrent/short circuit protection circuit module. The charging power supply circuit module is connected with a battery voltage/current detection circuit module, the battery voltage/current detection circuit module is connected with the microcontroller MCU, and the overvoltage/overcurrent/short-circuit protection circuit module selects a patch fuse. The microcontroller MCU controls the work of the overvoltage/overcurrent/short-circuit protection circuit module according to the battery voltage/current signal detected by the battery voltage/current detection circuit module so as to complete the overvoltage/overcurrent/short-circuit protection of the battery; however, the conventional battery protection circuit can only realize overvoltage/overcurrent/short-circuit protection, and cannot realize more comprehensive battery protection.
In addition, with the development of science and technology, the fields of electric vehicles, robots, electric automobiles and the like are developed rapidly, and power used by the industries all adopt power batteries as energy sources, which promotes the increase of battery requirements, but before the development of the industries is not standardized, the specifications of the batteries are more, and the batteries have various specifications, such as 24V batteries, 36V batteries, 48V batteries and the like. Different products use batteries of different specifications. The current product can only support the power supply of one specification battery, and can not realize the simultaneous on-site operation of batteries with different specifications. Once the electric quantity of the battery of the product is insufficient, the battery can only be charged or replaced; if a single product can use batteries with different specifications, on one hand, the working time of the product can be prolonged, and the product is prevented from stopping working under the condition of insufficient battery power; on the other hand, the universality and the convenience of the battery can be improved; however, the existing battery protection circuit only aims at the overcharge, overdischarge, overvoltage, overcurrent and overtemperature protection of the battery, and the application scenes are battery charging and battery discharging; if a product uses multiple battery specifications simultaneously, for example a high voltage specification battery and a low voltage specification battery are connected to load circuit jointly and discharge, if adopt current battery protection circuit, high voltage battery can discharge to low voltage battery, directly causes the damage to low voltage battery, can't realize the protection to respective battery.
Disclosure of Invention
In order to solve the above technical problems, it is an object of the present invention to provide a battery protection circuit and a multi-level battery protection circuit for realizing single cell and multi-level battery protection.
The technical scheme adopted by the invention is as follows: a battery protection circuit comprises a battery input end connected with a battery, a circuit connecting end used for voltage input and output, a voltage comparison circuit, a first switch control circuit, a first switch tube and a first diode, wherein the first switch control circuit is used for controlling the on-off of the first switch tube; the battery input end and the circuit connecting end are respectively connected with the input end of the voltage comparison circuit, the output end of the voltage comparison circuit is connected with the input end of the first switch control circuit, the output end of the first switch control circuit is connected with the control end of the first switch tube, the negative output end of the first switch tube is connected with the battery input end, the negative output end of the first switch tube is connected with the positive electrode of the first diode, the negative electrode of the first diode is connected with the positive output end of the first switch tube, the positive output end of the first switch tube is connected with the circuit connecting end, and the voltage comparison circuit compares the voltage of the battery input end and the circuit connecting end to control the output of the first switch control circuit so as to control the on-off of the first switch tube.
Further, the voltage comparison circuit includes a first voltage division circuit, a second voltage division circuit and a voltage comparator, the battery input terminal is connected to the input terminal of the first voltage division circuit, the circuit connection terminal is connected to the input terminal of the second voltage division circuit, the output terminal of the first voltage division circuit and the output terminal of the second voltage division circuit are respectively connected to the input terminal of the voltage comparator, and the output terminal of the voltage comparator is connected to the input terminal of the first switch control circuit.
Further, the first switch control circuit comprises a PWM signal generating circuit, a second switch tube, a third switch tube, a fourth switch tube and a transformer, the output end of the voltage comparison circuit is respectively connected with the control end of the second switch tube and the control end of the third switch tube, the positive output end of the second switch tube is connected with the first input end of the transformer, the negative output end of the second switch tube is connected with the negative output end of the third switch tube, the positive output end of the third switch tube is connected with the second input end and the center tap connecting end of the transformer, the second input end and the center tap connecting end of the transformer are both connected with the power supply, the positive output end of the fourth switch tube is connected with the negative output end of the second switch tube, the control end of the fourth switch tube is connected with the output end of the PWM signal generating circuit, the negative output end of the fourth switch tube is grounded, and the output end of the transformer is connected with the control end of the first switching tube.
Furthermore, the battery protection circuit further comprises a fifth switch tube and a logic circuit, wherein the logic circuit is used for outputting a level signal to control the on-off of the fifth switch tube, the output end of the logic circuit is connected with the control end of the fifth switch tube, the negative output end of the fifth switch tube is connected with the positive output end of the fourth switch tube, and the positive output end of the fourth switch tube is connected with the second input end of the transformer and the center tap connecting end.
Further, the second switching tube and/or the third switching tube and/or the fourth switching tube and/or the fifth switching tube are/is an NPN triode, a base of the NPN triode is a control end of the switching tube, an emitter of the NPN triode is a negative output end of the switching tube, and a collector of the NPN triode is a positive output end of the switching tube.
Further, the PWM signal generating circuit is a square wave signal generating circuit.
Furthermore, the battery protection circuit further comprises a second switch control circuit, wherein the second switch control circuit is used for outputting a control signal to control the output of the first switch control circuit so as to control the on-off of the first switch tube; and the output end of the second switch control circuit is connected with the input end of the first switch control circuit.
Furthermore, the first switch tube is an NMOS tube, a gate of the NMOS tube is a control end of the first switch tube, a source of the NMOS tube is a negative output end of the first switch tube, and a drain of the NMOS tube is a positive output end of the first switch tube.
The technical scheme adopted by the invention is as follows: the multi-level battery protection circuit comprises batteries of at least two specifications and battery protection circuits in one-to-one correspondence with the batteries, wherein the output ends of the batteries are connected with the battery input ends of the battery protection circuits, and the circuit connecting ends of the battery protection circuits are connected with the input ends of load circuits.
Furthermore, the multi-level battery protection circuit further comprises a charging power supply, and the output end of the charging power supply is connected with the circuit connecting end of the battery protection circuit and the input end of the load circuit.
The invention has the beneficial effects that:
the invention relates to a battery protection circuit, which comprises a battery input end connected with a battery, a circuit connecting end used for voltage input and output, a voltage comparison circuit, a first switch control circuit, a first switch tube and a first diode, wherein the first switch control circuit is used for controlling the on-off of the first switch tube; the voltage comparison circuit compares the voltage of the battery input end and the circuit connecting end to control the output of the first switch control circuit, and then controls the on-off of the first switch tube, so as to ensure that the battery is not damaged by the high voltage input by the circuit connecting end, and the technical problems that in the prior art, a battery protection circuit only has an overvoltage/overcurrent/short circuit protection function, has a single function and cannot meet the requirement of battery protection are solved.
The invention has the following beneficial effects:
the invention discloses a multi-level battery protection circuit, which comprises batteries with at least two specifications and battery protection circuits corresponding to the batteries one to one, wherein the output ends of the batteries are connected with the battery input ends of the battery protection circuits, the circuit connecting ends of the battery protection circuits are connected with the input ends of load circuits, one battery corresponds to one battery protection circuit, independent protection of the batteries with various specifications is realized, and the technical problem that in the prior art, when the batteries with multiple specifications supply power to the load at the same time, a high-voltage battery discharges a low-voltage battery, and the low-voltage battery is damaged is solved.
Drawings
The following further describes embodiments of the present invention with reference to the accompanying drawings:
FIG. 1 is a block diagram of a charging/discharging overcharge/overdischarge protection circuit of a lithium battery in the prior art;
FIG. 2 is a schematic circuit diagram of an embodiment of a battery protection circuit of the present invention;
FIG. 3 is a schematic circuit diagram of an embodiment of a PWM signal generating circuit of a battery protection circuit according to the present invention;
fig. 4 is a block diagram of a multi-level battery protection circuit according to an embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
A battery protection circuit, referring to fig. 2, fig. 2 is a schematic circuit diagram of an embodiment of a battery protection circuit according to the present invention; the battery protection circuit comprises a battery input end VCC _ B + connected with a battery, a circuit connection end VCC _ P + used for voltage input and output, a voltage comparison circuit A, a first switch control circuit B, a first switch tube Q1 and a first diode D1, wherein VCC _ B + is connected with the positive electrode of the battery, VCC _ B-is connected with the negative electrode of the battery, and the first switch control circuit B is used for controlling the on-off of the first switch tube Q1; the battery input end VCC _ B + and the circuit connection end VCC _ P + are respectively connected with the input end of a voltage comparison circuit A, the output end of the voltage comparison circuit A is connected with the input end of a first switch control circuit B, the output end of the first switch control circuit B is connected with the control end of a first switch tube Q1, the negative output end of the first switch tube Q1 is connected with the battery input end VCC _ B +, the negative output end of the first switch tube Q1 is connected with the positive electrode of a first diode D1, the negative electrode of the first diode D1 is connected with the positive output end of a first switch tube Q1, the positive output end of a first switch tube Q1 is connected with the circuit connection end VCC _ P +, the voltage comparison circuit A compares the voltage of the battery input end and the voltage of the circuit connection end VCC _ P + to control the output of the first switch control circuit B, and further controls the on-off of the first switch tube Q1. The circuit connection terminal VCC _ P + not only serves as an output terminal of the battery protection circuit to output voltage, but also serves as an input terminal of an external charging power supply to input voltage. When the battery is connected with the battery input end of the battery protection circuit, the voltage comparison circuit A and the first switch control circuit B can control the on-off of the first switch tube Q1 to control whether the output of the battery is available, and the unidirectional conduction function of the first diode D1 is utilized to ensure that the battery is not damaged by the high voltage input by the circuit connection end, thereby overcoming the technical problems that the battery protection circuit only has the overvoltage/overcurrent/short circuit protection function, has single function and can not meet the requirement of battery protection in the prior art.
As a further improvement of the technical solution, referring to fig. 2, the voltage comparison circuit a includes a first voltage division circuit, a second voltage division circuit and a voltage comparator, in this embodiment, the first voltage division circuit includes resistors R8, R12, R18 and R20, the second voltage division resistor includes resistors R9, R13, R19 and R21, and the voltage comparator is a voltage comparator U4 of TLV7011 model; the battery input terminal VCC _ B + is connected to the input terminal of the first voltage divider circuit (one terminal of the resistor R8), the circuit connection terminal VCC _ P + is connected to the input terminal of the second voltage divider circuit (one terminal of the resistor R9), the output terminals VREF1 and VREF2 of the first voltage divider circuit are respectively connected to the input terminal of the voltage comparator U4, and the output terminal of the voltage comparator U4 is connected to the input terminal of the first switch control circuit B. Specifically, after the battery is connected with the battery protection circuit, the battery input end VCC _ B + and the circuit connection end VCC _ P + are stepped down in equal proportion, and the obtained voltage is: VREF1 ═ VCC _ B + (R18+ R20)/(R18+ R20+ R8+ R12), and in this embodiment, VREF1 is set at around 3V; VREF2 ═ VCC _ P + (R19+ R21)/(R19+ R21+ R9+ R13), and in this embodiment, VREF2 is set at around 3V; VREF1 and VREF2 are amplified by triodes Q6 and Q7 and then are respectively input to the inverting input end and the non-inverting input end of the voltage comparator U4; the voltage comparator U4 compares the two input voltages, and outputs logic '1', namely level 5V, when the voltage of the non-inverting input terminal IN + is greater than the voltage of the inverting input terminal IN-; when the voltage of the non-inverting input terminal IN + is less than the voltage of the inverting input terminal IN-, logic '0' is output, i.e., level 0V.
As a further improvement of the technical solution, referring to fig. 2, the first switch control circuit B includes a PWM signal generating circuit, a second switch tube Q2, a third switch tube Q3, a fourth switch tube Q4 and a transformer U3, an output terminal of the voltage comparison circuit a (i.e. an output terminal of the voltage comparator U4) is respectively connected to a control terminal of the second switch tube Q2 and a control terminal of the third switch tube Q3, a positive output terminal of the second switch tube Q3 is connected to a first input terminal of the transformer U3, i.e. the pin1 of the transformer U3, a negative output terminal of the second switch tube Q2 is connected to a negative output terminal of the third switch tube Q3, a positive output terminal of the third switch tube Q3 is connected to a second input terminal of the transformer U3, i.e. the pin3 of the transformer U3, a pin2 of the center tap, i.e. the pin2 of the transformer U3, a second input terminal of the transformer U3, i.e. the pin3 of the transformer U3, and a pin 362 of the center, the positive output end of the fourth switching tube Q4 is connected with the negative output end of the second switching tube Q2, the control end of the fourth switching tube Q4 is connected with the output end PWM of the PWM signal generating circuit, the negative output end of the fourth switching tube Q4 is grounded, and the output end of the transformer U3, namely pins 4 and 5 of the transformer U3, is connected with the control end of the first switching tube Q1. Specifically, the ratio of the numbers of the primary and secondary windings of the transformer U3 is 1:2, so Pin2-Pin 3: the voltage at the center tap is 5V when Pin4-Pin5 is 1:4, and the voltage of +/-20V can be obtained at the output ends of the secondary pins Pin4-Pin5 by controlling the levels of Pin1 and Pin3 pins. Further, the PWM signal generating circuit is a square wave signal generating circuit, referring to fig. 3, fig. 3 is a schematic circuit diagram of a specific embodiment of the PWM signal generating circuit of the battery protection circuit according to the present invention; the square wave signal generating circuit is realized by using inverters (U1 and U2), resistors and capacitors, square waves meeting requirements can be adjusted by adjusting the numerical values of the resistors R2, R3, R4 and R5 and the capacitors C1 and C2, and the generated square waves are used for controlling the transformer; in this embodiment, the square wave signal generating circuit generates a square wave with a frequency of 1Khz and a duty ratio of 50%. Furthermore, the first switch transistor Q1 is an NMOS transistor, the gate of the NMOS transistor is the control terminal of the first switch transistor Q1, the source of the NMOS transistor is the negative output terminal of the first switch transistor Q1, and the drain of the NMOS transistor is the positive output terminal of the first switch transistor Q1. In addition, the second switching tube Q2 and/or the third switching tube Q3 and/or the fourth switching tube Q4 are NPN triodes, a base of the NPN triode is a control end of the switching tube, an emitter of the NPN triode is a negative output end of the switching tube, and a collector of the NPN triode is a positive output end of the switching tube. In addition, the first switching tube Q1 may also be a triode, and the second switching tube Q2 and/or the third switching tube Q3 and/or the fourth switching tube Q4 may also be implemented by a MOS transistor.
In fact, when there is no external charging source, the battery is connected to the battery input terminal of the battery protection circuit, and the battery voltage is output through the circuit connection terminal. Specifically, the voltage of the circuit connection terminal VCC _ P + is: VCC _ P + (VCC _ B +) -0.7V, and the forward voltage drop of the first diode D1 is calculated as 0.7V; the circuit connection terminal VCC _ P + and the battery input terminal VCC _ B + are proportionally reduced and then input to the voltage comparator U4, because the voltage of the circuit connection terminal VCC _ P + is less than the voltage of VCC _ B +, the voltage comparator U4 outputs 0 level, the second switch tube Q2 is closed, the third switch tube Q3 is conducted, the Pin2-Pin3 end of the transformer U3 has a square wave with the frequency of 1KHz, the level amplitude is 5V, the secondary output terminal Pin4-Pin5 of the transformer outputs 20V of a forward square wave, the voltage passes through the voltage stabilizing diodes (D5 and D2) and then charges the capacitor C4, the voltage of the C4 end of the capacitor C is 20VDC, the switch of the first switch tube Q1 can be controlled, the gate-source voltage Vgs of the first switch tube Q1 is larger than Vgs (ON), the first switch tube Q1 is conducted, the battery normally supplies power to the outside, the Rson conduction impedance is very small, the first switch tube adopts IPB020 NMOS 3G model, the on-resistance is 2 milliohm, the voltage drop can be ignored, and the voltage output by the circuit connection end is the input voltage of the battery input end.
In addition, when there is a charging power supply higher than the battery voltage, the charging power supply is input to the battery protection circuit through the circuit connection terminal VCC _ P +. The voltage of the circuit connection terminals VCC _ P + and VCC _ B + is proportionally reduced and then input to the voltage comparator U4, because the voltage of the circuit connection terminal VCC _ P + is greater than the voltage of VCC _ B +, the voltage comparator U4 outputs 5V level, the second switch tube Q2 is turned on, the emitter voltage of the second switch tube Q2 is 5V-0.7V-4.3V, the base voltage of the third switch tube Q3 is about 3.3V, and therefore the third switch tube Q3 is not turned on. A Pin2-Pin1 end of the transformer U3 is provided with a square wave with the frequency of 1KHz, the level amplitude is 5V, a secondary output end Pin4-Pin5 of the transformer U3 outputs negative voltage, the capacitor C4 is charged after the negative voltage passes through a voltage stabilizing tube, the voltage of-20V is arranged at two ends of the capacitor C4, the on-off of the first switch tube Q1 can be controlled, the grid-source voltage Vgs < Vgs (ON) of the first switch tube Q1, the first switch tube Q1 is closed, and the battery cannot supply power to the outside. The external charging power cannot be input due to the unidirectional conduction of the first diode D1, so that the safety of the battery circuit and the battery can be protected.
As a further improvement of the technical solution, referring to fig. 2, the battery protection circuit further includes a second switch control circuit C, where the second switch control circuit C is configured to output a control signal to control the output of the first switch control circuit B, so as to control the on/off of the first switch tube Q1; the output end of the second switch control circuit C is connected with the input end of the first switch control circuit B. Specifically, the second switch control circuit C includes a fifth switch tube Q5 and a logic circuit, the logic circuit is configured to output a level signal to control on/off of the fifth switch tube Q5, an output end EN of the logic circuit is connected to a control end of the fifth switch tube Q5, a negative output end of the fifth switch tube Q5 is connected to a positive output end of the fourth switch tube Q4, a positive output end of the fourth switch tube Q4 is connected to both the second input end of the transformer U3, i.e., the 3-pin of the transformer U3, and the center-tap connection end, i.e., the 2-pin of the transformer U3. In this embodiment, the fifth switch Q5 is an NPN transistor, a base of the NPN transistor is a control terminal of the fifth switch Q5, an emitter of the NPN transistor is a negative output terminal of the fifth switch Q5, and a collector of the NPN transistor is a positive output terminal of the fifth switch Q5. The logic circuit is used for outputting a high level and a low level to control the on-off of the fifth switching tube Q5. Under the condition that the external charging power supply can charge the battery, the output end EN of the control logic circuit outputs a high level to control the conduction of the fifth switch tube Q5, further control the transformer U3 to output a positive voltage to control the conduction of the first switch tube Q1, and the external charging power supply can charge the battery. The second switch control circuit C is arranged to realize charging control of the battery, and the charging control is very convenient and fast. In addition, the fifth switching tube Q5 can also be implemented by a MOS tube.
Referring to fig. 2 and 4, fig. 4 is a block diagram of a multi-level battery protection circuit according to an embodiment of the present invention; the multi-level battery protection circuit comprises batteries with at least two specifications and battery protection circuits corresponding to the batteries one by one, and the battery protection circuit is realized by adopting the battery protection circuit; the output end of the battery is connected with the battery input end of the battery protection circuit, and the circuit connecting end of the battery protection circuit is connected with the input end of the load circuit through the backboard circuit. Furthermore, the multi-level battery protection circuit also comprises a charging power supply, and the output end of the charging power supply is connected with the circuit connecting end of the battery protection circuit and the input end of the load circuit through the backboard circuit. The multi-level battery protection circuit comprises a battery pack, a battery protection circuit, a backboard circuit, a load circuit and a charging power supply, wherein the battery pack can consist of a plurality of battery specifications such as a battery specification 1, a battery specification 2, a battery specification … … and a battery specification n; the batteries output specified voltage by using 18650 specification batteries in series-parallel combination, the voltage of a single 18650 specification battery is 3.7V-4.2V, and if 12 batteries are connected in series, the total output voltage is 44.4V-50.4V; the output voltage of batteries with different specifications is different, such as 24V, 36V and 48V. The battery protection circuit protects the low-voltage battery from being burnt by the discharge of the high-voltage battery when batteries with different specifications are connected to the load circuit together to discharge the load circuit, monitors the voltage of the circuit connecting end in real time, and immediately closes a first switching tube of the battery protection circuit after the voltage higher than the battery voltage is monitored, so as to protect the battery; and the charge and discharge of the battery are controlled through load logic. The backboard circuit is used for connecting the charging power supply, the load circuit and the plurality of battery protection circuits, and directly connects the charging power supply, the load circuit and the plurality of battery protection circuits together to realize current transfer. In addition, the charging power supply is a direct current power supply connected to the charger; the voltage range of a single 18650 battery is 3.7V-4.2V, while a battery with the 48V specification adopts 12 batteries which are connected in series, the output voltage range of the battery is 44.4V-50.4V, and a charging power supply of 50.4VDC is needed; the 36V-specification battery adopts 9 batteries connected in series, the output voltage range of the battery is 33.3V-37.8V, and a charging power supply of 37.8VDC is needed; the 24V-specification battery adopts 6 batteries connected in series, the output voltage range of the battery is 22.2V-25.2V, and a 25.2VDC charging power supply is required. Finally, the load circuit is an electronic product load circuit, such as a motherboard, a motor drive, a motor, and the like.
In the multi-level battery protection circuit, one battery corresponds to one battery protection circuit, so that independent protection of batteries with various specifications is realized, and the technical problem that in the prior art, when the batteries with various specifications supply power to a load at the same time, a high-voltage battery discharges a low-voltage battery, and the low-voltage battery is damaged is solved.
Referring to fig. 2 and 4, when the battery discharges to the outside, the batteries with different voltage specifications are connected to the back panel circuit through the battery protection circuit, and the battery protection circuit judges the voltage at the input end of the battery and performs on-off control on the output current of the battery. The following specific working procedures are described below:
in the first case, a single battery is connected to the backplane circuitry:
first, the battery is discharged through the first diode D1, the tube drop of the first diode D1 is about 0.7V (subsequently calculated according to the tube drop of 0.7V), and the voltage obtained by the backplane circuit is (VCC _ B +) -0.7V. The voltage of the circuit connection end is VCC _ P + (VCC _ B +) -0.7V, and the forward voltage drop of the first diode D1 is calculated according to 0.7V; VCC _ P + and VCC _ B + are proportionally reduced and then input to a voltage comparator U4, because the voltage of VCC _ P + is less than the voltage of VCC _ B +, the voltage comparator U4 outputs 0 level, a second switch tube Q2 is closed, a third switch tube Q3 is switched on, square waves with the frequency of 1KHz are arranged at the Pin2-Pin3 end of a transformer U3, and the level amplitude is 5V. The secondary output ends Pin4-Pin5 of the transformer U3 output forward voltage, the grid-source voltage Vgs of the first switch tube Q1 is larger than Vgs (ON), the first switch tube Q1 is conducted, and the battery supplies power to the outside normally. The tube voltage drop of the first diode D1 is 0.7V; the first switch Q1 is an NMOS transistor. The pressure drop is very small and can be basically ignored; after the first switch tube Q1 is turned on, current flows out from the first switch tube Q1, at this time, the first diode D1 does not work, and all current flows out through the first switch tube Q1 to supply power to the load circuit.
In the second case, the case where multiple size batteries are inserted into the backplane circuit at the same time:
A. the low-voltage battery is firstly in place, and the high-voltage battery is inserted onto the circuit of the back plate
The low-voltage battery is firstly inserted into the circuit of the backboard, for example, the voltage of the battery is 36V, the 36V power supply supplies power to the load circuit through the first diode, the load circuit works, the condition of supplying power by a single battery is repeated, and the battery can normally supply power to the load after passing through a series of circuits.
The high-voltage battery is inserted into the backboard circuit, for example, the battery voltage is 48V, the voltage of the 48V power supply passing through the first diode is 48V-0.7V-47.3V, the power supply voltage received by the load circuit is 47.3V, after the battery protection circuit works, the first switch tube is turned on, the first diode of the battery protection circuit corresponding to the 48V battery stops working, and the output voltage of the battery protection circuit is 48V. The battery protection circuit corresponding to the 36V battery recognizes that high voltage is input to act, the 48V voltage and the 36V voltage are reduced in the same proportion and then are compared by the voltage comparator, the 48V is greater than 36V, the voltage comparator outputs logic '1', the level value is 5V, the second switch tube Q2 is opened, the center tap of the transformer is conducted with the upper end of the transformer, the gate-source voltage of the first switch tube Q1 is negative at the moment, the first switch tube Q1 is closed, and the voltage comparator TLV7011, the transformer and the triodes have reaction time within 1ms, so that the first switch tube Q1 can be closed within 5ms, meanwhile, the voltage of the first diode of the battery protection circuit of the 36V battery is reverse voltage, the first diode is not conducted, and the 36V battery is protected.
B. The high-voltage battery is firstly in place, and the low-voltage battery is inserted onto the circuit of the back plate
The high-voltage battery is firstly inserted into the backplane circuit, for example, the battery voltage is 48V, the 48V power supply supplies power to the load circuit through the first diode, the load circuit operates, through the process of supplying power by the single battery as described above, the first switch Q1 of the battery protection circuit is opened, the 48V supplies power to the load circuit, and the voltage received by the load circuit is 48V (the MOS transistor drop is negligible).
When a low-voltage battery is inserted onto the backplane circuit, for example, the voltage of the battery is 36V, and the first switch Q1 of the battery protection circuit of the 36V battery is turned off, and the first diode of the battery protection circuit of the 36V battery is reversed, the 48V battery cannot supply power to the 36V battery and the 36V battery cannot discharge power without the intervention of load logic. If the logic circuit controls the first switch tube Q1 of the 36V battery to be opened, the voltage of 47.3V and the voltage of 36V are reduced by the same proportion and then are compared by the voltage comparator TLV7011, 47.3V is greater than 36V, so the TLV7011 outputs logic '1', the level value is 5V, the second switch tube Q2 is opened, the center tap of the transformer is conducted with the upper end of the transformer, the gate-source voltage of the first switch tube Q1 is negative, the first switch tube Q1 is closed, and because the reaction time of the voltage comparator TLV7011, the transformer and the triode is within 1ms, the first switch tube Q1 of the battery protection circuit corresponding to 36V can be closed within 5ms, and the above actions are repeated, so the 36V battery cannot supply power to the load circuit.
When the 48V battery is discharged to a voltage lower than 36V, the high battery voltage and the 36V voltage are subjected to proportional voltage reduction and then are compared, the 36V voltage is higher than the battery voltage of the 48V battery, so that the TLV7011 outputs logic '0', the level value is 0V, the second switching tube Q2 is closed, the fifth switching tube Q5 is continuously switched, the Vbe voltage of the third switching tube Q3 is greater than the triode starting voltage of 0.6V, the center tap of the transformer is conducted with the lower end of the transformer, the grid-source voltage of the first switching tube Q1 is 5V in positive value at the moment, the first switching tube Q1 is opened, and the reaction time of the voltage comparator TLV7011, the transformer and the triode is within 1ms, so that the first switching tube Q1 of the battery protection circuit corresponding to the 36V battery can be opened within 5ms, the actions are repeated, and the 36V battery supplies power to the load circuit.
In summary, when the batteries with high and low voltage specifications are online at the same time, the batteries with high voltage specifications preferentially discharge to the load, and after the batteries with high and low voltage specifications discharge to a voltage lower than that of the batteries with low voltage specifications, the low-voltage batteries supply power to the load. Similarly, if 24V batteries, 36V batteries and 48V batteries are simultaneously on line, the 48V batteries supply power preferentially, and the 36V batteries discharge outwards when the 48V batteries stop outputting due to overdischarge; after the discharge of 36V is finished, the 24V battery is discharged to the outside.
Referring to fig. 2 and 4, the process of charging the battery by the charging power supply is described as follows:
A. in-place charging of single battery
The battery (e.g., 48V voltage) is discharged through the first diode, the tube drop of the first diode is about 0.7V (subsequently calculated according to the tube drop of 0.7V), and the voltage obtained by the backplane circuit is Vbattery-0.7V — 47.3V; as described above for single cell powering, a 48V battery can be normally discharged for a load. When the backboard circuit is powered by the charging power supply (for example, the charging voltage is more than 50.4V), the voltage of the charging power supply is larger than the voltage of the battery, and on one hand, the charging power supply supplies power to the load circuit; on the other hand, after the charging power supply charges the battery, 50.4V is added to VCC _ P +, the battery protection circuit is activated, the first switch tube Q1 is turned off, the external high voltage cannot damage the 48V battery, when the load logic confirms that the battery is charged, the logic circuit pulls the EN Pin high, the fifth switch tube Q5 is turned on, the Pin2-Pin3 port of the transformer U3 has the PWM wave function, the secondary Pin4-Pin5 of the transformer U3 outputs +20V voltage, so that the first switch tube Q1 is turned on, the external power supply can charge the 48V battery, and the charging management of the battery can be realized by adjusting the charging voltage waveform.
B. Multi-cell in-place charging
When the batteries with different specifications are in place at the same time, the high-voltage battery supplies power to the load. When the back panel circuit is powered by the charging power supply, the voltage of the charging power supply is higher than that of any battery, on one hand, the charging power supply supplies power to the load, and on the other hand, the charging power supply charges the battery, and the process is as described above and is not described herein again. When the voltage of the battery is equal to the charging voltage, the charging is ended. Under the condition that the load logic circuit is not inserted, because the voltage of the charging power supply is higher than the voltage of the battery, the first switch tube Q1 can not be opened through the battery protection circuit, so the charging power supply can not charge the battery; under the condition of the intervention of the load logic circuit, the logic circuit outputs an enabling signal, the first switch tube Q1 is opened, and the charging power supply charges the battery.
The invention allows batteries with various specifications to be simultaneously applied to a load, for example, the input range of load voltage is 20V-60V, the specification of the battery can be 24V, 36V and 48V, and under the condition that the batteries with three specifications are simultaneously in place, the high-voltage battery always preferentially works, for example, the 48V battery always supplies power to the load in preference to the 24V and 36V batteries, and the 36V battery always supplies power to the load in preference to the 24V battery; in addition, the invention solves the problem of battery damage caused by different battery voltages under the condition that a plurality of batteries work simultaneously, and by monitoring the load voltage in real time, when the high voltage higher than the battery voltage is connected to the circuit connecting end of the battery protection circuit, the first switch tube is immediately closed, thereby avoiding the damage to the interior of the battery and providing a guarantee for the use of more batteries of the prior product.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. A battery protection circuit is characterized by comprising a battery input end connected with a battery, a circuit connecting end used for voltage input and output, a voltage comparison circuit, a first switch control circuit, a first switch tube and a first diode, wherein the first switch control circuit is used for controlling the on-off of the first switch tube; the battery input end and the circuit connecting end are respectively connected with the input end of a voltage comparison circuit, the output end of the voltage comparison circuit is connected with the input end of a first switch control circuit, the output end of the first switch control circuit is connected with the control end of a first switch tube, the negative output end of the first switch tube is connected with the battery input end, the negative output end of the first switch tube is connected with the positive electrode of a first diode, the negative electrode of the first diode is connected with the positive output end of the first switch tube, the positive output end of the first switch tube is connected with the circuit connecting end, and the voltage comparison circuit compares the voltage of the battery input end and the circuit connecting end to control the output of the first switch control circuit so as to control the on-off of the first switch tube; the voltage comparison circuit comprises a first voltage division circuit, a second voltage division circuit and a voltage comparator, wherein the input end of the battery is connected with the input end of the first voltage division circuit, the circuit connection end is connected with the input end of the second voltage division circuit, the output end of the first voltage division circuit and the output end of the second voltage division circuit are respectively connected with the input end of the voltage comparator, and the output end of the voltage comparator is connected with the input end of the first switch control circuit;
the first switch control circuit comprises a PWM signal generating circuit, a second switch tube, a third switch tube, a fourth switch tube and a transformer, the output end of the voltage comparison circuit is respectively connected with the control end of the second switch tube and the control end of the third switch tube, the positive output end of the second switch tube is connected with the first input end of the transformer, the negative output end of the second switch tube is connected with the negative output end of the third switch tube, the positive output end of the third switch tube is connected with the second input end and the center tap connecting end of the transformer, the second input end and the center tap connecting end of the transformer are both connected with a power supply, the positive output end of the fourth switch tube is connected with the negative output end of the second switch tube, the control end of the fourth switch tube is connected with the output end of the PWM signal generating circuit, and the negative output end of the fourth switch tube is grounded, and the output end of the transformer is connected with the control end of the first switching tube.
2. The battery protection circuit according to claim 1, further comprising a fifth switching tube and a logic circuit, wherein the logic circuit is configured to output a level signal to control on/off of the fifth switching tube, an output end of the logic circuit is connected to a control end of the fifth switching tube, a negative output end of the fifth switching tube is connected to a positive output end of a fourth switching tube, and a positive output end of the fourth switching tube is connected to both the second input end and the center tap connection end of the transformer.
3. The battery protection circuit according to claim 2, wherein the second switching tube and/or the third switching tube and/or the fourth switching tube and/or the fifth switching tube are NPN transistors, a base of the NPN transistor is a control terminal of the switching tube, an emitter of the NPN transistor is a negative output terminal of the switching tube, and a collector of the NPN transistor is a positive output terminal of the switching tube.
4. A battery protection circuit according to any one of claims 1 to 3, wherein the PWM signal generating circuit is a square wave signal generating circuit.
5. The battery protection circuit according to any one of claims 1 to 3, further comprising a second switch control circuit, wherein the second switch control circuit is configured to output a control signal to control an output of the first switch control circuit, so as to control on/off of the first switch tube; and the output end of the second switch control circuit is connected with the input end of the first switch control circuit.
6. The battery protection circuit according to any one of claims 1 to 3, wherein the first switch tube is an NMOS tube, a gate of the NMOS tube is a control end of the first switch tube, a source of the NMOS tube is a negative output end of the first switch tube, and a drain of the NMOS tube is a positive output end of the first switch tube.
7. A multi-level battery protection circuit, comprising at least two types of batteries and the battery protection circuit of any one of claims 1 to 3 in one-to-one correspondence with the batteries, wherein the output terminals of the batteries are connected to the battery input terminals of the battery protection circuit, and the circuit connection terminals of the battery protection circuit are connected to the input terminals of the load circuit.
8. The multi-level battery protection circuit of claim 7, further comprising a charging power supply, wherein an output of the charging power supply is connected to both the circuit connection terminal of the battery protection circuit and the input of the load circuit.
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| CN102549877B (en) * | 2009-11-11 | 2015-11-25 | 美商源捷有限公司 | The interlock mechanism of many battery pack |
| KR101058682B1 (en) * | 2010-06-18 | 2011-08-22 | 주식회사 엘지화학 | Battery pack protection device that controls charge and discharge current of battery pack, battery pack and multi battery pack system including the same |
| CN103326407A (en) * | 2012-03-22 | 2013-09-25 | 宏碁股份有限公司 | Charging source detection switching device and method |
| CN102832596B (en) * | 2012-08-31 | 2014-10-29 | 深圳市汇川技术股份有限公司 | Low voltage electrombile drive protecting circuit and low voltage electrombile drive protecting method |
| CN203135416U (en) * | 2013-02-22 | 2013-08-14 | 江文瑞 | Charging protection circuit preventing battery voltage from flowing backward |
| CN104716715A (en) * | 2015-04-02 | 2015-06-17 | 青岛歌尔声学科技有限公司 | Multi-battery-based power supply circuit and electronic product with power supply circuit |
| CN105048575B (en) * | 2015-08-03 | 2018-03-16 | 成都宇能通能源开发有限公司 | It is a kind of to solve the problems, such as between different battery packs the mutually circuit and its method of discharge and recharge |
| JP6774628B2 (en) * | 2016-12-07 | 2020-10-28 | 株式会社オートネットワーク技術研究所 | Battery monitoring device protection circuit and battery monitoring device |
| CN206542207U (en) * | 2017-02-07 | 2017-10-03 | 长春工程学院 | A kind of reverse connection preventing pours in down a chimney charge protector of battery |
| CN207283201U (en) * | 2017-09-06 | 2018-04-27 | 成都星达微科技有限公司 | A kind of transmission line of electricity monitoring power supply comprising more battery units |
| CN107528373A (en) * | 2017-09-26 | 2017-12-29 | 东莞市奇立电源有限公司 | A relay switch control device and method thereof |
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Effective date of registration: 20231007 Address after: 518000 Wanke Yuncheng Phase 4, Dashi 1st Road, Xili Community, Xishan District, Shenzhen City, Guangdong Province (Centralized Commercial Project) A08 (12-08) Patentee after: Kandra (Shenzhen) Intelligent Technology Co.,Ltd. Address before: 20 / F, sannuo wisdom building, 3012 Binhai Avenue, Yuehai street, Nanshan District, Shenzhen, Guangdong 518000 Patentee before: CANDELA (SHENZHEN) TECHNOLOGY INNOVATION Co.,Ltd. |