Charge and discharge controller

Details Charge and discharge controller Charge and discharge controller

2002-02-19

2003-09-23

Tso, Edward H. (Department: 2838)

Electricity: battery or capacitor charging or discharging

Battery or cell discharging

With charging

Reexamination Certificate

active

06624614

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a rechargeable power source apparatus which is capable of controlling charge and discharge of a secondary battery on the basis of ON/OFF of a switching circuit.
2. Description of the Related Art
As for a conventional charged power source apparatus including a secondary battery, there is known a charge and discharge controlling circuit as shown in a circuit block diagram of FIG.
2
.
For example, such a configuration is disclosed in Japanese Patent Application Laid open No. Hei 4-75430 entitled “rechargeable power unit”. That is, a secondary battery
101
is connected between an external terminal −Vo and an external terminal +Vo through a switching circuit
103
. In addition, a charge and discharge controlling circuit
110
is connected in parallel with the secondary battery
110
. This charge and discharge controlling circuit
110
has the function of detecting a voltage of the secondary battery
101
.
When the secondary battery
101
is in the overcharge state (it means the state in which the voltage of the battery is higher than a predetermined voltage values hereinafter, this state is referred to as “the over-charge protection state”, when applicable), a signal is outputted from the charge and discharge controlling circuit
110
in such a way as to turn OFF a charging switch
112
of the switching circuit
103
.
On the other hand, when the secondary battery
101
is in the overdischarge state (it means the state in which the voltage of the battery is lower than a predetermined voltage value: hereinafter, this state is referred to as “the overdischarge protection state”, when applicable), a signal is outputted from the charge and discharge controlling circuit
110
in such a way as to turn OFF a discharging switch
111
of the switching circuit
103
. In addition, a charge current and a discharge current can be limited in such a way that the charge current or the discharge current is caused to flow through the switching circuit
103
having a resistance component, whereby the generated voltage of the external terminal −Vo is monitored to detect that this voltage has reached a certain voltage to turn OFF the switching circuit
103
.
In other words, it is possible that when an excessive charge current is caused to flow, the charging operation is stopped (overcharge current control) and when an excessive discharge current is caused to flow, the discharging operation is stopped (overdischarge current control). Hereinafter, those states are respectively referred to as “the overcharge current protection state” and “the overdischarge current protection state” when applicable.
The charge and discharge controlling circuit operates to protect the battery from those states as described above.
SUMMARY OF THE INVENTION
In the case of the charge and discharge controlling circuit shown as the conventional example in
FIG. 2
, there arises the problem in that it is impossible to carry out the detection of the charge current with the overdischarge protection state being held, and the detection of the discharge current with the overcharge protection state being held.
Now, the problem in that it is impossible to carry out the detection of the charge current in the overdischarge protection state will hereinbelow be described specifically. Though in the overdischarge protection state, the discharging switch
111
shown in
FIG. 2
is in the OFF state, in the case where a battery charger
105
is connected between the external terminal +Vo and the external terminal −Vo in this state, the charge current is caused to flow through the secondary battery
101
, the discharging switch
111
and the charging switch
112
.
However, since the discharging switch
111
is in the OFF state, the charge current is forcedly caused to flow through a parasitic diode of the discharging switch
111
(shown in
FIG. 2
as a diode connected in parallel with the charging switch
111
). As a result, the voltage at the external terminal −Vo is dropped by the voltage Vf across the parasitic diode, and in this state, it is impossible to accurately detect the overdischarge current.
The problem in that it is impossible to carry out the detection of the discharge current in the overcharge protection state is also similar to the impossibility of the detection of the charge current in the overdischarge protection state.
In the light of the foregoing, the present invention has been made in order to solve the above-mentioned problems associated with the prior art, and it is therefore an object of the present invention to make it possible to carry out the detection of the overcharge current in the overdischarge state and the detection of the overcharge current in the overcharge state by detecting with respect to the charge current, the voltage developed across a resistance component of the charging switch
112
and by detecting, with respect to the discharge current, the voltage developed across a resistance component of the discharging switch
111
.


REFERENCES:
patent: 5808446 (1998-09-01), Eguchi
patent: 6118253 (2000-09-01), Mukainakano et al.
patent: 6232750 (2001-05-01), Podrazhansky et al.

Affiliated with

Also associated with

Rating

Charge and discharge controller does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Charge and discharge controller, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Charge and discharge controller will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3004126