JPH02273039A - Charger - Google Patents

Abstract

PURPOSE:To effect the optimum charging efficiently by a method wherein the trickle charging for a predetermined period of time and holding charging are effected in accordance with the kind of a battery as well as an ambient temperature when the output current of a DC/DC converter, which is obtained by high- frequency switching, has become lower than a predetermined value. CONSTITUTION:Two sets of DC/DC converted 4, opened and closed by high frequency wave, are connected in parallel to the DC output of a rectifier 3 connected to an AC power source 1 while the output side of the converters are connected in series to supply a power to load terminals 2. On the other hand, another output circuit is provided with a current detector 5 and a timer 6 is started when the value of a current has been reduced to a value, set by a resistor 7. The time-up time of the timer 6 is set by another resistor 8. An output voltage control circuit 9 inputs an output signal, controlled by the output of a temperature corrector 11, a detected current and the output of the timer 6, into the regulating terminal 10 of the DC/DC converter 4. A regulator 12 sets an initial value in accordance with the kind of the storage battery.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a battery charger that automatically charges a battery according to its charging characteristics.

(Prior Art) In recent years, batteries have come into widespread use in electric carts at golf courses, electric transport vehicles such as lifts in factories, and power sources for computers.

Particularly in places where a large number of batteries are used in one place, such as in electric transportation vehicles, it takes time and effort to replenish the electrolyte, so instead of the conventional liquid-filled type batteries, liquid-impregnated types, in which a separator is impregnated with electrolyte, and electrolytic Sealed batteries that are difficult to maintain, such as liquid-gel type batteries that are made of gelled liquid and attached to electrode plates, have come into use.

For example, as shown in the graph in Figure 4, the charging characteristics of these batteries are such that when initially charged at a constant current, the charging voltage gradually increases, and reaches a constant level when the battery is charged to about 80% of its capacity. When voltage charging occurs, the charging current decreases, and when the charging capacity exceeds 100%, standby charging occurs in which a small amount of current flows to prevent overcharging and compensate for self-discharge.

These charging characteristics are almost the same for liquid-filled, liquid-impregnated, and liquid-gel types, but for sealed liquid-impregnated and liquid-gel types, the optimal voltage when charging the foot voltage varies depending on the temperature. It has characteristics that vary greatly.

In other words, the constant voltage region (trickle charge) varies depending on the temperature during charging.
Since the charging voltage varies greatly, the optimal voltage with good charging efficiency that can complete charging in a few hours is, for example, 31 at 0°C.
．． What was 4V drops to 29.4V at 25°C.

Traditionally, this type of sealed battery charging machine has a special charger for each manufacturer's battery type, but this charger simply sets the charging time with a timer, and can be used at night or during the day. However, there was no function to adjust the optimal voltage, which varies greatly depending on the temperature during charging.

(Problems to be Solved by the Invention) The present invention eliminates the above-mentioned drawbacks, automatically detects charging temperature, and provides optimal charging according to various battery characteristics. To provide a charger that can efficiently charge voltage in a short time, is small in size, requires little installation space, and is easy to transport.

(Means for Solving the Problems) The present invention comprises: ``a DC-DC converter connected to a power source and using high-frequency switching operation, a current detector provided in the output circuit of this control, and a charging current detected by the current detector. a timer that operates when the voltage falls below a predetermined value; and an output voltage control circuit that is activated by the timer and adjusts the output voltage of the converter to a trickle charging voltage and a subsequent standby voltage.

This circuit is characterized by comprising a temperature compensator and an initial value setting device connected to this circuit.

(Function) Next, the function of the present invention will be described. The input terminal is connected to a power source, and the timer start current of the current detector is set in accordance with the capacity of the battery.

Similarly, the timer can be used to set the trickle charging time according to the battery being charged.

We also separately measure the temperature at the location where the charger is installed.
Set the initial temperature according to the type of battery being charged. This initial temperature setting only needs to be adjusted at the time of installation and does not need to be adjusted unless the type of battery is changed.

Next, when the output terminal is connected to the battery and the switch is turned on, the current is converted into a constant current and constant voltage with excellent charging efficiency by a high frequency switching operation of approximately 1 MHz using a DC-DC converter.

In this charging state, when charging is performed at a constant current, the charging voltage gradually increases, and when charging becomes constant voltage, the charging current gradually decreases.

This charging current is constantly measured by a current detector, and when the current falls below a preset value, this is detected and a detection signal is output to the timer, which activates the timer and operates the output voltage control circuit for a predetermined period of time. Then lower the voltage and enter constant voltage trickle charging.

During trickle charging, if the temperature of the battery changes due to a change in air temperature, the temperature compensator detects this and outputs a signal to the output voltage control circuit to adjust the optimal charging voltage according to the temperature change. It is set to automatically add 2gl.

After trickle charging is performed for a predetermined period of time by a timer, the battery shifts to standby charging in which a small amount of current flows to prevent overcharging and compensate for self-discharge.

(Embodiments) The present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is an input terminal connected to an AC power source, and 2 is an output terminal connected to a battery.

Two DC-DC converters 4, 4 with an output of 12V are connected to the input terminal l via a rectifier 3, which outputs 12V by high-frequency switching operation.
The units are connected in parallel to form a switching power supply.

Further, the output side of this DC-DC converter 4.4 is connected to the output terminal 2.2 and the DC converter 1.

A current detector 5 is provided in the output circuit between one DC-DC converter 4 and the output terminal 2, and a timer 6 is further connected to the current detector 5.

A semi-fixed resistor 7 for setting the start current of a timer 6 is connected to the current detector 5, and a semi-fixed resistor 8 for setting the operating time is connected to the timer 6.
detects when the charging current falls below a predetermined value,
A detection signal is output to a timer 6 to activate it.

Reference numeral 9 denotes an output voltage control circuit connected to the timer 6, the output side of which is connected to the adjustment terminal IO side of the DC-DC converter 4.

Reference numeral 11 denotes a temperature corrector formed of a thermistor, which is connected to the output voltage control circuit 9 to detect the temperature during charging and output this signal.

Further, an initial value setter 12 formed of a semi-fixed resistor is provided between the output voltage control circuit 9 and the DC-DC converter 4 to set the temperature at the time of installation depending on the type of battery.

Next, the operation of the charger having the above configuration will be explained.

First, connect input terminal 1 to a 200 V commercial AC power supply,
The semi-fixed resistor 7 attached to the current detector 5 is set to the charging current when the charging current reaches about 80% of the charging capacity according to the capacity of the battery to be charged. The semi-fixed resistor 8 attached to the timer 6 is also adjusted to set the trickle charging time of the battery to be charged.

We also separately measure the temperature at the location where the charger is installed.
Initial value setter 1 sets the initial temperature according to the type of battery to be charged.
Set in 2. This initial value setting device 12 can be adjusted only at the time of installation, and there is no need to worry about adjusting it unless the type of battery is changed.

After the preliminary adjustment is completed in this way, the switch 13 is inserted by connecting the battery to the output terminal 2.2.

When the switch 13 is turned on, the rectifier 3 converts 50 to 60 cycles of alternating current into direct current, and the converted current is transferred to a DC-DC converter 4, which uses a high-frequency switching operation of about IMHz to provide high charging efficiency. Converted to constant current and constant voltage.

Two DC-DC converters 4, 4 with an output of 12V are connected in series, and the battery is charged with 24V.

If this charging state is shown in the graph of Figure 3, at first, the current is constant! As the battery is charged, the charging voltage V gradually increases.
When the battery is charged to about 80% capacity, it changes to constant voltage charging.
Conversely, the charging current gradually decreases.

This charging current is constantly measured by a current detector 5.

When the voltage drops to a preset value of, for example, 1.5A, when this is detected and a detection signal is output to the tie-/-6, the timer 6 is activated and the output voltage control circuit 9 is activated for a predetermined period of time to lower the charging voltage. and enters trickle charging.

This trickle charging is performed for about 12 hours, and if the temperature of the battery changes due to changes in the air temperature during this time, this is detected by the temperature compensator 11 formed by a thermistor, and a signal is output to the output voltage control circuit 9, and the temperature The system automatically adjusts the optimal charging voltage according to changes.

Trickle charging is performed in which the battery is charged little by little over a predetermined period of time using the timer 6, and when the charging capacity exceeds 100%, the charging voltage is further lowered to prevent overcharging and to perform standby charging where a small amount of current flows to compensate for self-discharge. to move to.

Therefore, all you need to do is set the detection current of the current detector and trickle charging time of the timer, and set the initial temperature according to the type of battery in the place where the charger is installed. Automatically adjusts the optimal charging voltage rectified in stages, allowing for efficient charging.

In addition, the DC-DC converter is a molded type, so it is small and inexpensive, and the charger is also smaller, requiring less installation space, and has excellent vibration and moisture proofing and insulation properties, making it suitable for use as a charging station for mounting on a single vehicle. can also be applied.

In the above embodiment, two DC-DC converters 4 with an output of 12V are connected, but if the output is 24V, one unit may be used, and when connecting to a DC power supply, the rectifier 3 may be connected. unnecessary.

Furthermore, the temperature compensator 11 may be installed between the output voltage control circuit 9 and the initial value setter 12 for setting the initial temperature, as shown in FIG.

(Effects of the Invention) As explained above, according to the charger according to the present invention, the charging temperature is automatically detected and the charging voltage is automatically adjusted to the optimum charging voltage according to various battery characteristics, and moreover, high frequency switching operation is possible. It can be efficiently charged in a short time with constant current and constant voltage using a DC-DC converter, and it is also compact, requires little installation space, and is easy to transport.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a charger according to an embodiment of the present invention, and FIG.
The figure is a circuit diagram of a charger according to another embodiment, FIG. 3 is a graph showing charging characteristics by the charger of the present invention, and FIG. 4 is a graph showing charging characteristics of various batteries. l...Input terminal 2...Output terminal 3...
Rectifier 4... DC-DC converter 5... Current detection base 6... Timer 7.8... Semi-fixed resistor 9... Output voltage controller 11... Temperature compensator 12... Initial stage Value setter roll circuit

Claims (1)

[Claims] A DC-DC converter connected to a power source and operated by high-frequency switching; a current detector provided in the output circuit of this converter; and a timer that operates when the charging current detected by the current detector becomes less than a predetermined value; It is characterized by comprising an output voltage control circuit that is activated by the timer and adjusts the output voltage of the converter to a trickle charge voltage and a subsequent standby voltage, and a temperature compensator and an initial value setter connected to this circuit. charger.