KR0134765B1 - Rechargable rapid charging circuit of battery - Google Patents

Abstract

The present invention relates to a battery charging circuit, in particular a battery fast charging circuit having a fast charging function and an overcharge preventing function, in a battery fast charging circuit for supplying a constant charging current to the battery through a resistor, connected in series to the resistor A switching element that connects or disconnects a path to which the current is supplied to the battery, and detects a battery voltage when the battery is charged, and when the battery voltage rises to a maximum voltage and drops to a full charge voltage that appears in a real full charge state. It is provided with an overcharge prevention circuit for the switching element to block the path, to provide a fast charging circuit capable of fast charging and overcharge protection.

Description

Fast charging circuit of rechargeable battery

1 is a conventional battery charging circuit without a quick charge function.

2 is a characteristic diagram of the charging current of FIG.

3 is a conventional battery rapid charging circuit.

4 is a battery charge and discharge characteristics.

5 is a battery fast charging circuit according to the present invention.

The present invention relates to a battery charging circuit, and more particularly to a battery fast charging circuit having a fast charging and overcharge protection.

A typical battery is used after being recharged for a certain period of time. Conventional recharge circuits do not have a fast charging function has a disadvantage that takes a long time when charging.

1 is a conventional battery charging circuit without a quick charging function. Referring to the operation of FIG. 1, the DC voltage is received through the A + terminal and the A- terminal, and the charging current I _{B is} generated through the resistor R _b to charge the battery. When charging is complete, power is supplied to the load through diode D2. If the charging voltage of the battery is V _B , the charging current I _B is

It is expressed as As charging progresses, the battery voltage V _B gradually increases. Therefore, as shown in equation (1), the charging current I _B gradually decreases. As a result, the charging progress of the battery becomes slow. This relationship is shown in FIG. 2 as the relationship between the charging time and the charging current.

Therefore, due to the decrease in the charging current, the time taken for the full charge of the battery (Full charge) was very long.

The conventional technology for solving this problem is a battery fast charging circuit.

The battery fast charging circuit is a circuit having a function of maintaining a constant amount (or at an appropriate level) of the current supplied to the battery so as to quickly perform battery charging.

3 illustrates a conventional battery rapid charging circuit.

Referring to the configuration and operation of FIG. 3, the charging current control unit 33 which receives the power from the rectifier 31 and supplies the charging current to the battery 30, and the resistor r _fb 37 connected to the battery 30 are connected. A charge current detection circuit 34 which detects a charge current and feeds it back to the charge current controller 33, and a memory diode connected to both ends of the battery 30 and conducting when the charge peak voltage V _{P or} higher recorded therein is exceeded. The short circuit detecting unit 36 detects the conduction of the 35 and the memory diode 35 and transfers it to the charging current controller 33 to stop charging.

3 illustrates the operation. The switch SW 32 designates a charging start. When charging is started, the charging current detection circuit 34 detects the magnitude of the charging current and feeds it back to the charging current controller 33. Accordingly, the charging current controller 33 operates to keep the charging current constant. Therefore, rapid charging is achieved by adjusting the charging current.

However, the conventional fast charging circuit shown in FIG. 3 has a problem of terminating charging before it is fully charged. That is, since the full charge of the battery is performed after the highest voltage V _P , as shown in the characteristic diagram of the rechargeable battery shown in FIG. 4, the conventional fast charge circuit is not fully charged.

4 will be described in more detail. After charging starts, the battery's voltage reaches its peak, V _P. But at this time, it is not fully charged. If charging continues, the battery is fully charged, at which time the full charge voltage V _F is slightly lower than V _P. During charging, the battery has a V _F value once at ⓓ point and one time at ⓑ as it rises, and an ⓐ point having a maximum value V _P between ⓓ and ⓑ. When the charged battery is used as a load power source, the charge voltage is rapidly decreased when the battery reaches the ⓒ point where the charge voltage is exhausted while maintaining the discharge voltage V _N after passing point ⓔ having the charging start voltage V _C.

The conventional fast charging circuit of FIG. 3 has a problem in that when the charging voltage of the battery reaches the V _P value stored in the memory diode, the charging is terminated and thus, full charging is not possible.

In addition, the compact design becomes difficult due to the use of a start switch.

Accordingly, an object of the present invention is to provide a rechargeable battery rapid charging circuit that solves the above problems.

Another object of the present invention is to provide a rechargeable battery rapid charging circuit capable of rapid charging and preventing overcharge.

The present invention for achieving the above object is characterized in that it comprises a charging current control circuit for controlling the charging current supplied to the battery, and an overcharge protection circuit for determining the charge or not to cut off the path to which the charging current is supplied to the battery do.

The charging current control circuit operates to supply a constant charging current irrespective of a phenomenon in which the charging current decreases as the voltage of the battery increases after the start of charging, and the overcharge prevention circuit detects the time of full charge and inflows the battery of the charging current. By blocking the operation, it prevents overcharge. Therefore, it is possible to configure a fast charging circuit that can achieve the above object of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIG. 4.

The construction and function of well-known circuits in the following description is weak in the description, and according to the present description, all of ordinary skill in the art will fully understand and be able to implement.

5 is a fast charging circuit diagram of a battery according to the present invention.

The Q1 and Q2 in FIG. 5 is a switching element, R _b and R _fb is the resistance element, D1 is the back-flow preventing diode. The power supply voltage is input through the A + and A- terminals.

As a result, the charging current I _B flows into the B + terminal of the battery through the switching element Q2 through the charging resistor R _B , and charging starts.

The charging current adjusting circuit 51 inputs the charging current I _B and the battery voltage V _B.

As the battery voltage increases, the charging current I _B decreases as mentioned in Equation (1). In order to solve this problem, it should be noted that increasing the charging current by reducing the charging resistance is one of the inherent ideas of the present invention.

That is, by adjusting the switching element Q1 connected in parallel with the charging resistance R _b to adjust the synthesis resistance of R _b and RQ1 (which can be changed by the resistance component of Q1), the magnitude of the charging current I _B inversely proportional to the synthesis resistance is adjusted. Therefore, it is possible to remove the phenomenon that the charging current is reduced, thereby maintaining the charging current at a constant size. As a result, rapid charging is possible.

Next, the overcharge prevention function will be described. The overcharge preventing circuit 52 checks the battery voltage. The charging curve of the battery voltage is as shown in FIG. Referring to FIG. 4, when charging is continued for a predetermined time and the battery voltage reaches the magnitude V _F of ⓓ, the overcharge prevention circuit 52 recognizes this as a rising edge of the pulse. The battery voltage will then reach the point ⓑ that is fully charged past the peak V _P , again representing the voltage V _F. At this time, the overcharge protection circuit recognizes this as the falling edge of the pulse. That is, it is recognized that one pulse is applied and then erased. At this time, the overcharge protection circuit operates to cut off the path of the charging current by turning off the switching element Q2 which is the path of the charging current. Therefore, since the charging current is no longer supplied to the fully charged battery, the battery does not overcharge.

As described above, according to the rapid charging circuit according to the present invention, the charging current control circuit capable of continuously supplying a predetermined charging current to the battery and an overcharge prevention circuit for detecting the full charge time to block the path of the charging current It is possible to implement a fast charge circuit with a fast charge function and overcharge protection.

In the exemplary embodiment of FIG. 5, the battery voltage is designed to be detected at the positive terminal of the battery. Alternatively, the battery voltage may be designed to be detected at the negative terminal of the battery. In order to explain this, it should be noted that in FIG. 5, there are connecting lines shown by dotted lines in the charging current control circuit 51 and the over-discharge prevention circuit 52 at the negative terminal of the battery. In this case, the R _bf resistor may be omitted.

Although the circuit and its function illustrated in FIG. 5 have been described in the present embodiment, it will be understood by those skilled in the art that various modifications are possible within the technical scope of the present invention.

Claims (1)

A battery fast charging circuit for supplying a constant charging current to a battery through a resistor, the battery comprising: a switching element connected in series with the resistor to connect or disconnect a path through which a charging current is supplied to the battery; And a recharge battery fast charging circuit for detecting and switching the path of the switching element when the battery voltage rises to a maximum voltage and then falls to a full charge voltage that appears in a real full charge state. .