JPH06335176A - Charge/discharge power supply apparatus - Google Patents

Abstract

PURPOSE:To provide a charge/discharge power supply apparatus which is small in size but can cope with a wide variety of battery characteristics. CONSTITUTION:As a switching device TSW is provided on the primary side of a transformer T1 for PWM control, the secondary output voltage V1 of the transformer can be varied linearly. Therefore, a constant power type power supply can be realized by monitoring the output voltage V1, so that a dynamic range as a charge/discharge power supply can be expanded even if the size is small. Further, as a minimum necessary voltage can be superposed upon a battery voltage by reducing the ON-period of the switching device TSW at the time of discharge, an additional transformer which is necessary in a conventional constitution can be eliminated and, moreover, unnecessary power consumption in a constant current controller (TR, RX, AMP and VREF) can be eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging / discharging power source device used as a charging power source when charging a battery and as an electronic load when discharging a battery.

[0002]

2. Description of the Related Art As one of conventionally known charging / discharging power supply devices, a circuit configuration shown in FIG. 3 is known.

In FIG. 3, an AC line is connected to the primary windings of the two transformers T1 and T2. Then, a control element (for example, a MOS FET bipolar transistor, an active element such as an electron tube) TR, and a current detection resistor RX
The constant current control circuit including the reference voltage power supply VREF and the differential amplifier AMP controls the current flowing through the battery BATT to a constant value. This constant current control circuit
It works not only during charging but also during discharging.

However, when discharging, the battery BATT
Since the MOS transistor TR of the constant current control circuit does not operate when the output voltage of the battery drops below a predetermined voltage, the DC voltage ΔV obtained from the secondary side of the second transformer T2 is changed to the output voltage of the battery BATT. In addition, the circuit configuration is added.

[0005]

In the above-mentioned conventional charge / discharge power supply device, the battery B is charged and discharged.
The voltage applied to the ATT is fixedly determined by the turns ratio of the transformers T1 and T2.

Therefore, when designing the charging / discharging power supply device, the ratings of the transformers T1 and T2, the ratings of the rectifying diodes D1 and D2, and the maximum voltage / current of the battery expected to be used are taken into consideration. The rating of the control element TR, the size of the heat sink, the value of the current detection resistor RX, etc. had to be determined in advance.

For this reason, the design must exceed the actually required power capacity, which causes the drawback that not only the manufacturing cost increases but also the external size of the device increases.

Therefore, in view of the above points, an object of the present invention is to provide a charging / discharging power supply device which is compact and can cope with a wide range of battery characteristics.

[0009]

In order to achieve such an object, the present invention provides a transformer for a charging / discharging power supply device used as a charging power source when charging a battery and as an electronic load when discharging a battery. A switching element is connected in series with the next winding to turn on / off the switching element.
The power supply means for generating a linear variable voltage in the secondary winding of the transformer by controlling the off time, the rectifying means for smoothing the output of the power supply means, and the rectifying means are connected to the latter stage, Constant current control means for controlling the current flowing through the battery, and generating a voltage of a predetermined value in the secondary winding of the transformer by controlling the on / off time of the switching element when the battery is discharged, An offset voltage adding means for adding the voltage of the predetermined value to the output voltage of the battery is provided.

[0010]

In the charging / discharging power supply device according to the present invention, the transformer 1
Since the PWM control is performed by providing the switching element on the secondary side, the secondary side output voltage of the transformer can be linearly varied. Therefore, a constant power type power supply can be realized by monitoring the output voltage, and the dynamic range as a charging / discharging power supply can be expanded while being compact.

Further, by controlling the on / off time of the switching element at the time of discharging, it becomes possible to superimpose a necessary minimum voltage on the battery voltage.
As compared with the conventional example, not only an extra transformer (T2: see FIG. 3) is unnecessary, but also unnecessary power consumption in the constant current control circuit can be eliminated.

[0012]

EXAMPLES Examples of the present invention will be described in detail below.

FIG. 1 is a circuit diagram showing a charging / discharging power supply device according to an embodiment of the present invention. In this figure, the same elements as those in the conventional example shown in FIG. 3 are designated by the same reference numerals.

The differences between the present embodiment shown in FIG. 1 and the conventional example shown in FIG. 3 are as listed below.

(I) Only one transformer is connected to the AC input line and the second transformer T2 is unnecessary.

(Ii) On the primary side of the transformer T1, the switching transistor TSW and the transistor TSW are turned on.
By providing the switching control circuit CNT that controls the ON / OFF time, the secondary side output voltage of the transformer T1 can be changed linearly.

(Iii) The DC voltage V1 obtained by the rectifying diode D1 and the smoothing capacitor C1 is monitored by the rectified voltage detection circuit DET and fed back to the switching control circuit CNT, whereby a constant power type power supply can be obtained.

(Iv) During discharge, the switching control circuit C
By instructing NT to be in the "discharge mode", the above-mentioned DC voltage V1 can be fixed at about 5 volts. As a result, even if the output voltage of the battery BATT reaches 0 volt, the voltage of about 5 volt is always added, so that the constant current control circuit (consisting of TR, RX, AMP, and VREF). It does not stop working. In addition, it is possible to sufficiently cope with a test of a battery having a low output voltage of about 1.3 V such as a button battery.

The reason why the DC voltage V1 is set to about 5 volts during discharging is as shown in FIG.

That is, although the MOS transistor TR shown in FIG. 1 is drawn as one transistor, in order to obtain a required current capacity, for example, a plurality of power MOS FETs are connected in parallel. . Therefore,

[0021]

[Outer 1]

Connected to each power MOS FET

[0023]

[Outside 2]

[0024]

[Outside 3]

Occurs in two cables connected to the output terminals of the battery BATT

[0026]

[Outside 4]

It is necessary to superimpose a voltage (offset voltage) of about 5 V on the battery output as a whole.

The circuit does not operate normally at a voltage of 5 V or less, and when the voltage of 5 V or more is applied, the MOS
The voltage applied to the transistor TR increases unnecessary power consumption of the TR itself, resulting in extremely poor efficiency.

[0029]

As described above, according to the present invention, since the switching element is provided on the primary side of the transformer to perform the PWM control, the secondary side output voltage of the transformer can be linearly varied. Besides, a constant power type power supply can be realized by monitoring the output voltage. As a result, it is possible to obtain a small-sized charge / discharge power supply device capable of coping with a wide range of battery characteristics.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an operation during discharging in the present embodiment.

FIG. 3 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 T1 Transformer CNT Switching control circuit DET Rectification voltage detection circuit RX Current detection resistor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H02M 7/217 9180-5H

Claims (1)

[Claims] 1. A charging / discharging power supply device used as a charging power source when charging a battery and as an electronic load when discharging a battery, wherein a switching element is connected in series with a primary winding of a transformer,
Power supply means for generating a linear variable voltage in the secondary winding of the transformer by controlling the on / off time of the switching element; rectifying means for smoothing the output of the power supply means; and the rectifying means. A constant current control unit connected to a latter stage of the transformer to control a current flowing through the battery, and a predetermined value in the secondary winding of the transformer by controlling an on / off time of the switching element when the battery is discharged. Charging / discharging power supply device, comprising: an offset voltage adding means for generating the voltage of 1. and adding the voltage of the predetermined value to the output voltage of the battery.