CN210517831U

CN210517831U - Reverse connection prevention protection circuit and charger

Info

Publication number: CN210517831U
Application number: CN201921541849.4U
Authority: CN
Inventors: 葛伟飚; 覃国兵; 侯永军
Original assignee: Shanghai Inovation Electrical Co ltd
Current assignee: Shanghai Jingfan yibeixun Electrical Technology Co., Ltd
Priority date: 2019-09-17
Filing date: 2019-09-17
Publication date: 2020-05-12
Anticipated expiration: 2029-09-17

Abstract

The utility model provides an anti-reverse connection protection circuit and charger, should prevent reverse connection protection circuit and include charging circuit, first control circuit, second control circuit, third control circuit and comparison circuit; the charging circuit comprises a first power supply, a relay, a storage battery charging connector and a sampling resistor, wherein the first power supply is used for charging the storage battery, the storage battery charging connector is used for generating pulse voltage, the storage battery charging connector is used for being connected with the storage battery, the first control circuit, the second control circuit, the third control circuit and the comparison circuit jointly control the on-off of the relay, the normally open contact of the relay is in an off state when the relay is not charged, and the normally open contact of the relay is in an on state when the relay is charged. The utility model discloses an use relay and a plurality of switching device, realize multiple protection, have and prevent the transposition and prevent flowing backward the function to there are overcurrent protection and short-circuit protection, low cost, the reaction is sensitive, has improved the reliability of circuit and charger.

Description

Reverse connection prevention protection circuit and charger

Technical Field

The utility model relates to a technical field that charges, concretely relates to prevent reverse connection protection circuit and have this charger that prevents reverse connection protection circuit.

Background

Along with the popularization of electric bicycles, the requirements on safe, reliable, portable and quick chargers are higher and higher. Especially, the reverse connection prevention protection function in the charger is a function which is required to be provided by the new national standard. Normally, the reverse connection prevention protection is realized by utilizing the unidirectional conductivity of the diode, the connection method is simple and reliable, but the power consumption influence is very large under the condition of inputting large current. This results in low efficiency and large heat generation, requiring the addition of a heat sink. In addition, a diode bridge can be used to rectify the input, so that the circuit always has the correct polarity, but the voltage drop of the diode consumes energy, which is usually twice of the power consumption of a single diode. In addition, the switch characteristic of the MOS tube can be utilized to control the connection and disconnection of the circuit to realize the reverse connection prevention protection circuit, and the problems of voltage drop and overlarge power consumption existing in the scheme of reverse connection prevention of the diode power supply are solved due to the small internal resistance of the power MOS tube. The field effect transistor for protection is a PMOS field effect transistor or an NMOS field effect transistor. In the case of a PMOS, the gate and source are connected to the ground terminal and power terminal of the protected circuit, respectively, and the drain is connected to the substrate of the PMOS device in the protected circuit. In case of NMOS, its grid and source are connected to the power supply terminal and ground terminal of the protected circuit, respectively, and its drain is connected to the substrate of the NMOS element in the protected circuit. The on-resistance of the NMOS tube is smaller than that of the PMOS tube, and the NMOS tube is preferably selected. Once the power supply polarity of the protected circuit is reversely connected, the field effect tube for protection can form a circuit break, thereby preventing the field effect tube element in the circuit from being burnt by current and protecting the whole circuit. However, the cost of the MOS transistor with high current, high voltage and low internal resistance is high, which is not favorable for reducing the cost. The market urgently needs an anti-reverse connection protection circuit and a charger with low cost and high reliability.

SUMMERY OF THE UTILITY MODEL

In view of the above problems, the utility model provides an anti-reverse connection protection circuit and charger, this anti-reverse connection protection circuit includes charging circuit, first control circuit, second control circuit, third control circuit and comparison circuit; the charging circuit comprises a first power supply, a relay, a storage battery charging connector and a sampling resistor, wherein the first power supply is used for charging a storage battery, the relay is connected with the positive electrode of the first power supply, the storage battery charging connector is used for generating pulse voltage, the sampling resistor is connected with the negative electrode of the first power supply, the storage battery charging connector is used for being connected with the storage battery, the first control circuit, the second control circuit, the third control circuit and the comparison circuit jointly control the on-off of the relay, the normally open contact of the relay is in an off state when the relay is not charged, the normally open contact of the relay is in a closed state; the first control circuit comprises a second power supply, a first switch device and a diode, the first switch device is connected with the two ends of the relay of the charging circuit in parallel after being connected with the diode in series, the anode of the first power supply is sequentially connected with the first switch device, the anode of the diode and the cathode of the diode are connected with the other end of the relay close to the joint, the anode of the second power supply is sequentially connected with the first switch device, the anode of the diode and the cathode of the diode are connected with the other end of the relay close to the joint, pulse voltage is obtained on the joint by driving the first switch device to be switched on/off, the diode can prevent current of the storage battery from flowing into the charger, the anti-backflow effect is achieved, and the anti-backflow effect can be achieved regardless; the second control circuit comprises a third power supply and a second switch device, the positive electrode of the third power supply is sequentially connected with the coil of the relay, the second switch device and the grounding end, and the normally open contact of the relay is closed by driving the second switch device to be conducted, so that the charging circuit forms a loop, namely the first power supply charges the storage battery; the third control circuit comprises a fourth power supply and a third switching device, the positive pole of the fourth power supply is sequentially connected with the third switching device and the first switching device, and the third control circuit is used for driving the third switching device to be cut off and cutting off the first switching device when receiving a reverse connection signal so as to enable the relay not to act, thereby realizing reverse connection protection; the comparison circuit comprises a first comparator and a second comparator, wherein the anode of the first comparator is connected with a second power supply, the anode of the second comparator is connected with a fourth power supply and is grounded through a resistor, the fourth power supply is used as the reference of the voltage of the comparator, the cathodes of the first comparator and the second comparator are connected with the common end between the sampling resistor and the joint of the charging circuit, the output end of the first comparator and the output end of the second comparator are connected to a third switching device, when the output ends of the first comparator and the second comparator are both at a high level, the third switching device is switched on, and when any one of the output ends of the first comparator and the second comparator is at a low level, the third switching device is switched off.

Preferably, the reverse connection prevention protection circuit further comprises a micro control unit, the micro control unit is powered by a fourth power supply, the micro control unit controls the relay through a second switching device, the micro control unit controls the output pulse signal through a first switching device, the micro control unit receives a reverse connection signal through an output end of the comparator to control a third switching device so as to control the first switching device and the second switching device, the micro control unit performs storage battery voltage detection through a second power supply voltage output end connected between the relay and a connector, and the micro control unit performs current detection through a current sampling end and a reverse connection voltage sampling end connected between the sampling resistor and the connector. Preferably, the third power supply is connected with the fourth power supply to play a role of voltage stabilization.

Preferably, the first switching device, the second switching device and the third switching device are all field effect transistors, and are N-channel enhancement type field effect transistors.

Preferably, the reverse connection prevention protection circuit further comprises a light-operated switch assembly, the light-operated switch assembly comprises an execution switch and a control end, the execution switch is controlled by a light signal of the control end, when a light ray is emitted from the control end, the execution switch is conducted, one end of the execution switch is connected with the anode of the second power supply, and the other end of the execution switch is connected with the grid electrode of the first field effect transistor. The control end is a light emitting diode, the anode of the light emitting diode is connected with the micro control unit through a resistor, and the cathode of the light emitting diode is grounded through the drain electrode of the third field effect transistor.

Preferably, a zener diode is connected between the anode of the first comparator and the ground terminal.

Preferably, a capacitor is connected in parallel to two ends of the voltage stabilizing diode.

Preferably, the reverse-connection prevention protection circuit further comprises a diode connected in parallel across the relay coil.

Preferably, the reverse connection protection circuit further comprises a capacitor connected in parallel with the negative electrode of the first comparator and the ground terminal, a capacitor connected in parallel with the positive electrode of the first comparator and the ground terminal, a capacitor connected in parallel with the negative electrode of the second comparator and the ground terminal, and a capacitor connected in parallel with the positive electrode of the second comparator and the ground terminal.

A charger comprises the reverse connection prevention protection circuit.

The utility model discloses an use relay and a plurality of switching device, realize multiple protection, have and prevent the transposition and prevent flowing backward the function to there are overcurrent protection and short-circuit protection, low cost, the reaction is sensitive, has improved the reliability of circuit and charger.

Drawings

Fig. 1 is a schematic diagram of an anti-reverse connection protection circuit of the present invention;

fig. 2 is a schematic diagram of the optimized reverse connection prevention protection circuit of the present invention;

fig. 3 is a schematic diagram of the reverse connection prevention protection circuit of the present invention connected to the storage battery on the basis of fig. 1;

wherein: JP 2-battery charging connector; JP 3-batteries; r1, J1, R3, R4, R5, R7, R8, R10, R11, R12, Ra5, Ra6, Ra7 — resistors; RI1 — current sampling resistor; d1, Da 1-diode; ka1 — relay; IC1 — photoswitch assembly; MCU-micro control unit; U1A — first comparator; U1B — second comparator; ZD 1-zener diode; q1-first switching device, first field effect transistor; qa 1-second switching device, second field effect transistor; q2-third switching element, third field effect transistor; MOS-metal oxide semiconductor; v54.6 — first supply voltage output; v54.6_2 — second supply voltage output; JDQ-Relay control Port; GND 2-current sampling, reverse voltage sampling end; VCC5 — fourth supply voltage output; VCC20 — third supply voltage output; LVD-receiving reverse signal port; 1. 2, 3, 4, 5, 6, 7, 8-pin.

Detailed Description

An anti-reverse-connection protection circuit is shown in fig. 1 and comprises a charging circuit, a first control circuit, a second control circuit, a third control circuit and a comparison circuit; the charging circuit comprises a first power supply for charging the storage battery, a relay Ka1, a storage battery charging connector JP2 for generating pulse voltage and a current sampling resistor RI1, wherein the storage battery charging connector for generating the pulse voltage is used for being connected with the storage battery, the first control circuit, the second control circuit, the third control circuit and the comparison circuit jointly control the on-off of the relay, the normally open contact of the relay is in an open state when the relay is not charged, and the normally open contact of the relay is in a closed state when the relay is charged; the first control circuit comprises a second power supply and a first switching device Q1, the second power supply is 15V, the second power supply is battery voltage plus 15V finally, the first switching device Q1 is driven to be switched on/off through a resistor J1, pulse voltage is obtained on a joint, and a diode D1 is connected in series after the first switching device is connected with a resistor R1 in parallel; the second control circuit comprises a third power supply and a second switching device Qa1, the voltage of the third power supply is about 20V, a relay series resistor Ra6 and Ra5 are connected, and the relay normally open contact is closed by driving the second switching device Qa1 to be conducted, so that the first power supply charges the storage battery; the third control circuit comprises a fourth power supply and a third switching device Q2, wherein the fourth power supply has the voltage of 5V and is used for driving the third switching device Q2 to be cut off and cutting off the first switching device Q1 through a resistor R4 when receiving the reverse connection signals from the receiving reverse connection signal ports LVD and R5, so that the relay does not act, and the reverse connection protection is realized; the comparison circuit comprises a first comparator U1A and a second comparator U1B, wherein the positive pole corresponding pin 3 of the first comparator is connected with a second power supply V54.6_2 through a resistor R7, the positive pole corresponding pin 5 of the second comparator is connected with a fourth power supply VCC5 through R11 and is grounded through a resistor R10, the fourth power supply is used as a reference of the voltage of the comparator, the

negative poles

2 and 6 of the first comparator and the second comparator are respectively connected with a current sampling end and a reverse voltage sampling end GND2 between the sampling resistor and a joint of the charging circuit through R12 and R8, the output terminal 1 of the first comparator and the output terminal 7 of the second comparator are connected with VCC5 through a resistor R9 and are connected with a third switching device through R5, the 8 of the first comparator is connected with VCC5, the 4 ground terminal of the first comparator is connected with the third switching device, when the output terminals 1 and 7 of the first comparator and the second comparator are both at high level, when any one of the output terminals 1 and 7 of the first comparator and the second comparator is at a low level, the third switching device is turned off.

In one embodiment, the reverse connection prevention protection circuit further comprises a Micro Control Unit (MCU), the micro control unit is powered by a fourth power supply, a relay control port JDQ of the micro control unit controls the relay through a second switching device, the micro control unit controls an output pulse signal through a first switching device, the micro control unit receives a reverse connection signal through an output end of a comparator to control a third switching device so as to control the first switching device and the second switching device, the micro control unit detects the voltage of the storage battery through a second power supply voltage output end V54.6_2 connected between the relay and a connector, and the micro control unit detects the current through a current sampling end connected between a sampling resistor and the connector and a reverse connection voltage sampling end GND 2. Preferably, the third power supply is connected with the fourth power supply to play a role of voltage stabilization.

In one embodiment, the first switching device, the second switching device and the third switching device are all field effect transistors and are N-channel enhancement type field effect transistors.

In one embodiment, the reverse connection prevention protection circuit further includes a photoswitch assembly IC1, the photoswitch assembly includes an execution switch and a control terminal, the execution switch is controlled by a light signal of the control terminal, when a light is emitted from the control terminal, the execution switch is turned on, one end of the execution switch is connected to the positive electrode of the second power supply, and the other end of the execution switch is connected to the gate of the first fet. The control end is preferably a light emitting diode, the anode of the light emitting diode is connected with the micro control unit through a resistor R4, and the cathode of the light emitting diode is grounded through the drain of the third field effect transistor.

In one embodiment, a zener diode ZD1 is connected between the anode 3 of the first comparator and ground.

In one embodiment, as shown in fig. 2, a capacitor C3 is connected in parallel across the zener diode.

In one embodiment, the reverse-connection prevention protection circuit further comprises a diode Da1 connected in parallel across the relay coil.

In one embodiment, the protection circuit for preventing reverse connection further comprises Ra7 connected in parallel to both ends of Ra6 and Qa1, R3 connected in parallel to both ends of Q1, C1 connected in parallel between the photodiode and Q2, and R6 connected between the drain of Q2 and the ground.

In one embodiment, the reverse-connection protection circuit further includes a capacitor C5 connected in parallel with the negative electrode 2 of the first comparator and the ground terminal, a capacitor C6 connected in parallel with the positive electrode 8 of the first comparator and the ground terminal, a capacitor C2 connected in parallel with the negative electrode 6 of the second comparator and the ground terminal, and a capacitor C4 connected in parallel with the positive electrode 5 of the second comparator and the ground terminal.

A charger comprises the reverse connection prevention protection circuit.

The utility model discloses an use relay and a plurality of switching device, realize multiple protection, have and prevent the transposition and prevent flowing backward the function, low cost, the reaction is sensitive, has improved the reliability of circuit and charger.

The specific working principle is as follows:

in case one, when the load is no longer loaded, the charger is connected with a 220V/AC power supply connector but is not connected with a storage battery:

1. the voltage of the first power supply voltage output terminal V54.6 in the charging circuit is added to the second power supply voltage output terminal V54.6_2 through a resistor R1, the voltage of the pin 1 of the connector JP2 is greater than the voltage of the pin 2, namely the voltage of the pin 3 of the first comparator U1A is greater than the voltage of the pin 2 of U1A, and the pin 1 of U1A outputs high level;

2. the voltage of VCC5 of the fourth power supply is divided into 5 pins of U1B by R11 and R10 to obtain a reference voltage, GND2 is 0V at this time, namely 6 pins of U1B are 0V, the voltage of 5 pins of U1B is greater than the voltage of 6 pins of U1B, and 7 pins of U1B output high level;

3. the pin 1 of the U1A and the pin 7 of the U1B output high level third fet Q2 to be turned on, the MCU outputs pulse voltage (high level 50 ms/low level 1000 ms) when receiving the LVD, the MCU controls the photoswitch module IC1 through the R4 to turn on/off the first fet Q1, and a pulse voltage is obtained at the connector JP 2.

In the second case, when the charger is loaded, the charger is connected with a 220V/AC power supply and then connected with a storage battery:

on the basis of the first condition, JP2 outputs pulse voltage, the MCU judges whether the storage battery is connected correctly through pulses, if the storage battery is connected correctly, the MCU stops sending pulse signals, the control IC1 enables Q1 to be cut off, meanwhile, the MCU controls the conduction of the second field effect transistor Qa1 through Ra6, the relay Ka1 is enabled to act, the Ka1 normally open contact is closed, the first power supply current is gradually increased to a set current value, and the storage battery is charged through JP 2.

In the third case, when the battery is reversely connected, the 220V/AC of the charger power supply is firstly connected, and then the storage battery is reversely connected

1. Voltage protection: the charger is powered on, as shown in fig. 3, the storage battery is reversely connected to JP2, the 1 pin of JP2 is connected with the negative electrode of JP3, and the 2 pin of JP2 is connected with the positive electrode of the storage battery, when the 2 pin voltage of JP2 is larger than the 1 pin voltage, namely the 2 pin voltage of U1A is larger than the 3 pin voltage of U1A, and the 1 pin of U1A outputs low level;

2. current protection: the charger is powered on, the storage battery is reversely connected to JP2, a pin 1 of JP2 is connected with the negative electrode of JP3, a pin 2 of JP2 is connected with the positive electrode of the storage battery, when the high level of the pulse is over, Q1 is conducted, voltage drop is generated on RI1, and when the voltage of a pin 6 of U1B is larger than the voltage of a pin 5 of U1B, a pin 7 of U1B outputs low level;

3. when any pin of 1 pin of U1A and 7 pin of U1B outputs low level, Q2 cut-off control IC1 cuts off Q1; in addition, when the MCU detects that the LVD is at a low level, the pulse output is stopped, and the Q1 is also in a cut-off state; in addition, the relay does not act, so that reverse connection protection is realized.

In the fourth case, when the battery is reversely connected, the storage battery is reversely connected firstly, and then the charger power supply is connected

1. The storage battery is reversely connected to JP2, a pin 1 of JP2 is connected with the negative pole of the storage battery, a pin 2 of JP2 is connected with the positive pole of the storage battery, the voltage of the pin 2 of JP2 is larger than the voltage of the pin 1, namely the voltage of the pin 3 of U1A is smaller than the voltage of the pin 2 of U1A, the charger power supply is switched on, and the pin 1 of U1A outputs low level;

2. when the pin 1 of the U1A outputs low level, the Q2 turns off the control IC1 to turn off the Q1; in addition, when the MCU detects that the LVD is at a low level, no pulse is output, and the Q1 is in a cut-off state; in addition, the relay does not act, so that reverse connection protection is realized.

Situation five, short circuit protection

When the 1 pin and the 2 pin of JP2 are short-circuited, a voltage drop is generated on RI1, when the 6 pin voltage of U1B is greater than the 5 pin voltage of U1B, the 7 pin of U1B outputs low level, so that Q2 is cut off, and the control IC1 enables Q1 not to be conducted; in addition, when the MCU detects that the LVD is at a low level, the Q1 is in a cut-off state, and the relay is disconnected, so that multiple short-circuit protection is realized.

Sixth, prevent flowing backward

In the case of a fully charged battery, with or without the charger 220V/AC power source unplugged, the current in the battery cannot flow back to the charger. When the storage battery is fully charged:

1. the micro control unit controls Qa1 to disconnect the relay, and the current of the storage battery can not flow into the charger;

2. the D1 diode also has the function of preventing the current of the storage battery from flowing into the charger, playing a role in preventing backflow, and playing a role in preventing backflow regardless of whether the power supply of the charger is disconnected.

The above-mentioned embodiments are only used for explaining the present invention, wherein the structure, connection mode, etc. of each component can be changed, and all the equivalent transformation and improvement performed on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. The reverse connection prevention protection circuit is characterized by comprising a charging circuit, a first control circuit, a second control circuit, a third control circuit and a comparison circuit;

the charging circuit comprises a first power supply, a relay, a storage battery charging connector and a sampling resistor, wherein the first power supply is used for charging a storage battery, the relay is connected with the positive electrode of the first power supply, the storage battery charging connector is used for generating pulse voltage, the sampling resistor is connected with the negative electrode of the first power supply, the storage battery charging connector is used for being connected with the storage battery, the first control circuit, the second control circuit, the third control circuit and the comparison circuit jointly control the on-off of the relay, the normally open contact of the relay is in an off state when the relay is not charged, the normally open contact of the relay is in a closed state;

the first control circuit comprises a second power supply, a first switch device and a diode, the first switch device is connected with the two ends of the relay of the charging circuit in parallel after being connected with the diode in series, the anode of the first power supply is sequentially connected with the first switch device, the anode of the diode and the cathode of the diode are connected with the other end of the relay close to the joint, the anode of the second power supply is sequentially connected with the first switch device, the anode of the diode and the cathode of the diode are connected with the other end of the relay close to the joint, and pulse voltage is obtained on the joint by driving the first switch device to be switched on/off;

the second control circuit comprises a third power supply and a second switch device, the positive electrode of the third power supply is sequentially connected with the coil of the relay, the second switch device and the grounding end, and the normally open contact of the relay is closed by driving the second switch device to be conducted, so that the charging circuit forms a loop, namely the first power supply charges the storage battery;

the third control circuit comprises a fourth power supply and a third switching device, the positive pole of the fourth power supply is sequentially connected with the third switching device and the first switching device, and the third control circuit is used for driving the third switching device to be cut off and cutting off the first switching device when receiving a reverse connection signal so as to enable the relay not to act, thereby realizing reverse connection protection;

the comparison circuit comprises a first comparator and a second comparator, wherein the anode of the first comparator is connected with a second power supply, the anode of the second comparator is connected with a fourth power supply and is grounded through a resistor, the fourth power supply is used as the reference of the voltage of the comparator, the cathodes of the first comparator and the second comparator are connected with the common end between the sampling resistor and the joint of the charging circuit, the output end of the first comparator and the output end of the second comparator are connected to a third switching device, when the output ends of the first comparator and the second comparator are both at a high level, the third switching device is switched on, and when any one of the output ends of the first comparator and the second comparator is at a low level, the third switching device is switched off.

2. The reverse connection prevention protection circuit according to claim 1, further comprising a micro control unit, wherein the micro control unit is powered by a fourth power supply, the micro control unit controls the relay through a second switching device, the micro control unit controls the output pulse signal through a first switching device, the micro control unit receives a reverse connection signal through an output end of the comparator to control the third switching device so as to control the first and second switching devices, the micro control unit performs battery voltage detection through a second power supply voltage output end connected between the relay and the connector, and the micro control unit performs current detection through a current sampling end and a reverse connection voltage sampling end connected between the sampling resistor and the connector.

3. The reverse-connection prevention protection circuit according to claim 2, wherein the third power supply is connected with the fourth power supply to perform voltage stabilization.

4. The reverse-connection prevention protection circuit according to claim 2, wherein the first switching device, the second switching device and the third switching device are field effect transistors and are N-channel enhancement type field effect transistors.

5. The reverse connection prevention protection circuit according to claim 4, further comprising a photoswitch assembly, wherein the photoswitch assembly comprises an execution switch and a control end, the execution switch is controlled by a light signal of the control end, when a light ray is emitted from the control end, the execution switch is conducted, one end of the execution switch is connected with the positive electrode of the second power supply, the other end of the execution switch is connected with the grid electrode of the first field-effect tube, the control end is a light-emitting diode, the positive electrode of the light-emitting diode is connected with the micro control unit through a resistor, and the negative electrode of the light-emitting diode is grounded through the drain electrode of the third field-effect tube.

6. The reverse-connection prevention protection circuit according to claim 1, wherein a zener diode is connected between the positive electrode of the first comparator and the ground terminal.

7. The reverse-connection preventing protection circuit as claimed in claim 6, wherein a capacitor is connected in parallel to two ends of the voltage stabilizing diode.

8. The reverse-connection prevention protection circuit according to claim 1, further comprising a diode connected in parallel across the relay coil.

9. The reverse-connection prevention protection circuit of claim 1, further comprising a capacitor connected in parallel to the negative pole of the first comparator and the ground, a capacitor connected in parallel to the positive pole of the first comparator and the ground, a capacitor connected in parallel to the negative pole of the second comparator and the ground, and a capacitor connected in parallel to the positive pole of the second comparator and the ground.

10. A charger, characterized in that it comprises an anti-reverse connection protection circuit according to any one of claims 1 to 9.