CN204391863U - Automatic power-off circuit and automatic power-off device for full storage battery of storage battery car - Google Patents

Abstract

The utility model relates to an automatic power-off circuit and an automatic power-off device when the battery of a battery car is fully charged, which is connected with a charger and a battery, and includes a step-down circuit, a three-terminal voltage stabilizing circuit, a voltage comparison circuit, a relay control circuit and a current detection circuit; The voltage circuit reduces the DC output of the adapter to 16V; the three-terminal voltage regulator circuit stabilizes the voltage from 16V to 12V and provides a reference power supply; the voltage comparison circuit judges that the circuit is in the state of charging or floating charge; the relay receives the signal from the voltage comparison circuit, And the DC output of the adapter is turned on or off through the relay switch; the current detection circuit judges the charging state of the circuit. The electric car battery is fully charged with an automatic power-off circuit and automatic power-off device that can be directly inserted between the battery car charger and the battery for use. After the electric car battery is fully charged, the DC power supply of the charger can be automatically disconnected, prolonging the life of the electric car battery. Longer service life, saving electric energy, cost is not high.

Description

Battery car battery is full of automatic power-off circuit and automatic power-off device

technical field

The utility model relates to an automatic power-off circuit for charging, in particular to an automatic power-off circuit when the storage battery of an electric vehicle is fully charged.

Background technique

At present, most electric vehicle batteries in my country use lead-acid batteries. There are generally two types of battery charging: one is a two-stage charger, that is, constant voltage charging first, and then trickle charging after reaching the threshold voltage; the other is a three-stage charger. Stage charger, that is, constant current first, then constant voltage charging, and then trickle charging after reaching the threshold voltage. There are many factors that affect the life of lead-acid batteries, one of the main factors is the "overcharge" of the battery, that is to say, most of the batteries are not worn out, but "charged out"! Although the charger is floating charging at the back, long-term floating charging is still very harmful to the battery. It not only wastes electric energy, but also easily causes damage to the battery electrodes; long-term overcharging will cause the battery to heat up, causing deformation of the battery shell and accelerating the battery. The evaporation of the electrolyte in the battery will shorten the service life of the battery. The best floating charging time is about two hours, but generally people use the car during the day and charge it at night, and few people will get up to unplug the power plug at night, and the fires caused by this are not uncommon. . Therefore, it is necessary to install an automatic power-off protection device on the basis of the original charger.

In the past, the patents for automatic power-off devices for electric vehicle charging were mainly to cut off the AC power, such as "An automatic power-off device for electric The automatic power-off device for car charging (application number 201210070631.1)" is to cut off the alternating current through the induction voltage control of the secondary coil of the transformer.

Utility model content

The technical problem to be solved by the utility model is: in order to provide an automatic power-off circuit when the battery of an electric vehicle is fully charged, it can automatically disconnect the DC power supply of the charger after the battery of the electric vehicle is fully charged without any modification of the charger itself, which belongs to Plug and play.

The technical solution adopted by the utility model to solve the technical problem is: a battery car battery is full of automatic power-off circuit, including a step-down circuit, a three-terminal voltage stabilizing circuit, a voltage comparison circuit, a relay control circuit and a current detection circuit; The voltage circuit is connected with the adapter of the charger, and the step-down circuit reduces the DC output of the adapter to 16V; the three-terminal voltage stabilizing circuit is connected with the step-down circuit, and the three-terminal voltage stabilizing circuit stabilizes the voltage from 16V to 12V, and provides a reference power supply; the voltage comparator circuit is connected with the three-terminal voltage stabilizing circuit, and the judging circuit is in charging or floating charging state; the relay control circuit is respectively connected with the adapter of the charger and the voltage comparator circuit, and the relay receives the signal sent by the voltage comparator circuit, And the DC output of the adapter is turned on or off through the relay switch; the current detection circuit is connected with the charger to judge the charging state of the circuit.

In a preferred embodiment of the present invention, it also includes a power supply display circuit, which is used to display whether the charger is powered on, and is connected with a red LED light by a resistor R1.

In a preferred embodiment of the present invention, the step-down circuit is connected by a resistor R2 and a Zener diode.

In a preferred embodiment of the present invention, the voltage comparison circuit is composed of resistors R3, R4, LM339 voltage comparator, and pull-up resistor R5. One end of resistor R3 is connected to the output end of the three-terminal voltage regulator, and one end is connected to the LM339 voltage regulator. For the inverting input of the comparator, one end of the resistor R4 is connected to the resistor R3, the other end is connected to the signal ground, one end of the pull-up resistor R5 is connected to the output end of the three-terminal voltage regulator, and the other end is connected to the output end of the LM339 voltage comparator.

In a preferred embodiment of the present invention, the comparison voltage at the reverse input terminal of the LM339 voltage comparator is 0.1V, and the comparison voltage is obtained from the voltage on R4 connected in series with resistors R3 and R4.

In a preferred embodiment of the present invention, the relay control circuit is connected to the cathode of the freewheeling diode D3 and the relay K1 by one end of the collector of the switching transistor Q1, and the emitter of the switching transistor Q1 is connected to the output of the three-terminal voltage regulator, green The anode of the light-emitting diode is connected to the positive pole of the relay K1 and the freewheeling diode D3, the negative pole of the green light-emitting diode is connected to the signal ground, one end of the relay K2 is connected to the negative pole of the freewheeling diode D4 and a normally closed contact of the time relay KT2, and the other end is connected to the freewheeling diode The positive pole of D4 is connected to the signal ground, the normally open contact K1 at one end of the time relay KT is connected to the negative pole of the freewheeling diode D5, and the other end is connected to the signal ground with the positive pole of the freewheeling diode D5.

The utility model also provides an automatic power-off device when the battery of the battery car is fully charged. The above-mentioned automatic power-off circuit for the battery of the battery car is used. The automatic power-off device for the battery car is connected to the charger of the battery car through the DC output socket of the charger. The accumulator access socket is connected with the accumulator.

The beneficial effects of the utility model are: the battery car battery of the utility model is fully charged and the automatic power-off circuit and the automatic power-off device can be directly inserted between the battery car charger and the battery for use, and can automatically disconnect the charging after the electric car battery is fully charged The DC power supply of the device prolongs the life of the battery of the electric vehicle, saves electric energy, and the cost is not high.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

Fig. 1 is the structural representation of the automatic power-off circuit when the storage battery of the battery car of the utility model is full;

Fig. 2 is a schematic diagram of the structure of the utility model battery car battery full automatic power-off device connected to the charger and the battery.

Detailed ways

Now in conjunction with accompanying drawing, the utility model is described in further detail. These drawings are all simplified schematic diagrams, and only schematically illustrate the basic structure of the utility model, so they only show the configurations related to the utility model.

As shown in Figure 1 and Figure 2, the battery car battery of the utility model is full of automatic power-off circuit and automatic power-off device mainly consists of eight parts: charger DC output access socket 1, power supply display circuit 2, step-down circuit 3, A three-terminal voltage stabilizing circuit 4 , a voltage comparison circuit 5 , a relay control circuit 6 , a current detection circuit 7 , and a battery access socket 8 .

The DC output socket 1 of the charger is used for the DC terminal of the electric vehicle charging adapter; the power supply display circuit 2 mainly indicates that the device is powered and can be charged; the step-down circuit 3 mainly connects the DC terminal of the electric vehicle charging adapter The output drops to 16V; the three-terminal voltage stabilizing circuit 4 is to stabilize the 16V voltage to 12V to provide a reference power supply for the voltage comparison circuit 5; the voltage comparison circuit 5 is mainly to judge whether the circuit is in a state of charging or floating charging; the relay control circuit 6 is Control the time relay switch KT1 at the DC output terminal to cut off the DC output of the electric vehicle charging adapter; the current detection circuit 7 is used to detect the charging current of the battery, and judge the charging state of the circuit by the magnitude of the charging current; the battery is connected to the socket 8 for electric Access to the charging interface of the vehicle battery.

The circuit design features of the present utility model are as follows:

(1) Power supply display circuit 2 is connected by resistor R1 and LED1 red light, and the current is designed to be about 20 mA;

(2) Step-down circuit 3 is connected by resistor R2 and 16V Zener diode, and the design current is about 30mA;

(3) Voltage comparator circuit 5 is composed of resistors R3, R4, LM339, and pull-up resistor R5. One end of resistor R3 is connected to the output end of the three-terminal voltage regulator 7812, and one end is connected to the inverting input of LM339; one end of R4 is connected to R3, and the other end is connected to Signal ground; one end of the pull-up resistor R5 is connected to the output end of the three-terminal voltage regulator 7812, and the other end is connected to the output end of the LM339. The circuit current is generated by R3 and R4, and is designed to be about 5 mA;

(4) The relay control circuit 6 connects the collector end of the switching transistor Q1 to the negative pole of the freewheeling diode D3 and the relay K1, the emitter of the switching transistor Q1 is connected to the output of the three-terminal voltage regulator 7812, and the positive pole of the green light-emitting diode LED2 is connected to the relay K1 and relay K1. The positive pole of the freewheeling diode D3 is connected, and the negative pole of the green light-emitting diode LED2 is connected with the signal ground. The design current of the circuit is about 40 mA; one end of the relay K2 is connected with the negative pole of the freewheeling diode D4 and a normally closed contact of the time relay KT2, and the other end is connected with the continuous The anode of the current diode D4 is connected to the signal ground, and the current design of this branch is about 40 mA; the normally open contact K1 at one end of the time relay KT is connected to the negative pole of the freewheeling diode D5, and the other end is connected to the positive pole of the freewheeling diode D5. Signal ground, the The branch current is designed to be about 40mA;

(5) The inverting input terminal of the LM339 voltage comparator is designed to have a comparison voltage of 0.1V, which is obtained from the voltage on R4 connected in series with resistors R3 and R4;

(6) The total design current through the front control circuit is about 175mA (0.175A), which is basically not affected compared with the large current (1.8A~2.5A) during normal charging.

The main working principle of the utility model is as follows:

(1) When the battery access socket DS2 of the device is first inserted into the battery, the circuit of the device does not work due to the action of the anti-current reverse diode D5;

(2) When the "charger DC input socket DS1" of the device is first connected to the charger DC output terminal, but the "battery socket DS2" is not connected to the battery, due to the normally open contact K2 and the time relay KT The closed contact KT1 is connected in parallel, the circuit is energized, the three-terminal voltage regulator 7812 outputs a stable voltage of 12V, and the voltage of the non-inverting input terminal of LM339 is 0, the voltage of the inverting input terminal is 0.1V, the output of LM339 is low, the transistor of Q1 is turned on, and the relay When K1 is energized, the normally closed contact K1 is closed, and the time relay KT is energized for timing. Since the time relay KT is set to be disconnected after 2 hours of power, the normally closed contact of the time relay KT is still in the closed conduction state; at the same time The relay K2 is energized, the normally open contact K2 is closed, and the circuit enters the charging state;

(3) When the device enters the charging state, since the low voltage of the battery is about 44V (48V battery pack), the circuit conducts a high-current charging state through D6 (48V12Ah charging current is 1.8 amps, 48V20Ah charging current is about 2.5 amps), current sampling The voltage on the resistor R6 is about (0.27V~0.37V), the resistor R6 is connected to the non-inverting input of the LM339 voltage comparator, so the non-inverting input is greater than the inverting input, the LM339 voltage comparator outputs a high level, the switching transistor Q1 is cut off, and the relay K1 is de-energized, the normally open contact K1 is disconnected, the time relay KT is de-energized, and the circuit enters the steady-state charging stage;

(4) When the battery is fully charged, the charging current drops to milliamp level (generally about 200mA~300mA), and the voltage drop on the current sampling resistor R6 drops to 0.045V, which is lower than that of the inverting input. 0.1V, the LM339 voltage comparator outputs low level, Q1 is turned on, the relay K1 is energized, and the green light-emitting diode LED2 lights up, indicating that the circuit enters the floating charging state. Since the normally open contact K1 is closed, the time relay KT is energized for timing, After 2 hours, the normally closed contacts of KT1 and KT2 are disconnected, causing the relay K2 to lose power, the normally open contact K2 is disconnected, and the power supply of the DC input socket of the charger is cut off.

Inspired by the above ideal embodiment according to the utility model, through the above description content, relevant staff can completely make various changes and modifications within the scope of not deviating from the technical idea of the utility model. The technical scope of this utility model is not limited to the content in the description, but must be determined according to the scope of the claims.

Claims (7)

1. battery of battery-driven truck is full of an automatic power-off circuit, it is characterized in that: comprise reduction voltage circuit, three-terminal voltage-stabilizing circuit, voltage comparator circuit, control relay circuit and current detection circuit;

Described reduction voltage circuit is connected with the adapter of charger, and the direct current of adapter exports and is down to 16V by reduction voltage circuit;

Described three-terminal voltage-stabilizing circuit is connected with reduction voltage circuit, and the voltage stabilizing of 16V voltage to 12V, and is provided reference power supply by three-terminal voltage-stabilizing circuit;

Described voltage comparator circuit is connected with three-terminal voltage-stabilizing circuit, and decision circuitry is in charging or floating charge state;

Described control relay circuit is connected with the adapter of charger and voltage comparator circuit respectively, the signal that relay receiver voltage comparison circuit sends, and the direct current of being opened or closing adapter by relay switch is exported;

Described current detection circuit is connected with charger, the charged state of decision circuitry.

2. battery of battery-driven truck as claimed in claim 1 is full of automatic power-off circuit, it is characterized in that: also comprise power display circuit, for show charger whether electric, be connected with LED red colored lamp by resistance R1.

3. battery of battery-driven truck as claimed in claim 1 is full of automatic power-off circuit, it is characterized in that: described reduction voltage circuit is connected with voltage stabilizing didoe by resistance R2.

4. battery of battery-driven truck as claimed in claim 1 is full of automatic power-off circuit, it is characterized in that: described voltage comparator circuit is made up of resistance R3, R4, LM339 voltage comparator, pull-up resistor R5, resistance R3 one end connects the output of three terminal regulator, one end connects the anti-phase input of LM339 voltage comparator, resistance R4 one end contact resistance R3, other end connection signal ground, pull-up resistor R5 one end connects the output of three terminal regulator, and the other end connects the output of LM339 voltage comparator.

5. battery of battery-driven truck as claimed in claim 4 is full of automatic power-off circuit, and it is characterized in that: the comparative voltage of described LM339 voltage comparator reverse input end is 0.1V, on the R4 that this comparative voltage is connected by resistance R3, R4, voltage obtains.

6. battery of battery-driven truck as claimed in claim 1 is full of automatic power-off circuit, it is characterized in that: described control relay circuit connects sustained diode 3 negative pole and relay K 1 by collector electrode one end of switch triode Q1, the emitter of switch triode Q1 connects the output of three terminal regulator, the positive pole of green LED is connected with sustained diode 3 positive pole with relay K 1, green LED negative pole is connected with signal ground, relay K 2 one end is connected with time relay KT2 mono-normally-closed contact with sustained diode 4 negative pole, the other end is connected with sustained diode 4 positive pole signal ground, time relay KT one end normally opened contact K1 is connected with sustained diode 5 negative pole, the other end is connected with sustained diode 5 positive pole signal ground.

7. a battery of battery-driven truck is full of auto-power-off device, it is characterized in that: adopt the battery of battery-driven truck as described in any one of claim 1-6 to be full of automatic power-off circuit, described battery of battery-driven truck is full of auto-power-off device and is connected with the charger of battery vehicle by charger direct current output access socket, is connected with storage battery by storage battery access socket.