JPH0467733A - Power supply provided with discharge control circuit - Google Patents

Abstract

PURPOSE:To stop discharge when discharge voltages differ considerably from one another by providing a discharge control circuit for detecting the difference of discharge voltage between batteries and interrupting power supply if thus detected difference is higher than a predetermined value in a power supply comprising a plurality of rechargeable batteries connected in series. CONSTITUTION:Absolute difference between voltages V1, V2 is compared with a reference voltage in a comparator 13 and when the voltage difference is lower, a Low logic level signal is outputted therefrom otherwise a High logic level signal is outputted. The output signal is fed to a switch 14 which opens upon transition of the output signal from Low to High thus interrupting a power supply path l1. In such a manner, power supply path is interrupted automatically and discharge of rechargeable battery is stopped.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a power supply device that uses a plurality of rechargeable batteries connected in series as a power supply, and particularly relates to a power supply device that uses a plurality of rechargeable batteries connected in series as a power supply, and in particular, The present invention relates to a discharge control circuit provided in the power supply device in order to prevent the occurrence of battery deterioration and the like.

[Prior Art and Problems to be Solved] As a power source for a mobile phone, etc., a power supply device having a power source configured by connecting a plurality of rechargeable batteries in series is known.

This power supply device has the following problems. That is, rechargeable batteries often have different charging and discharging characteristics due to variations in the physical or chemical properties of their constituent materials, or due to structural variations due to various factors in the manufacturing process. When using rechargeable batteries with such characteristic differences connected in series, especially when there is a difference in discharge voltage, the battery with the lower discharge voltage of the batteries connected in series has a deeper discharge depth. In some parts, the battery becomes over-discharged, and furthermore, if the difference in discharge voltage between the batteries is significantly different, the battery becomes forced-discharged, which causes shortened battery life and liquid leakage.

Therefore, the present invention was made in view of the above problems, and the object is to provide a discharge control circuit that can stop discharging when the discharge voltages of rechargeable batteries connected in series are significantly different. The object of the present invention is to provide a power supply device with the following features.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, in a power supply device including a plurality of series-connected rechargeable batteries as a power source, the discharge voltage of the rechargeable batteries is detected. a voltage detection means for detecting a potential difference between the rechargeable batteries based on the output of the voltage detection means; a comparison means for comparing the detected potential difference with a reference voltage; The present invention is characterized by comprising a cutoff means for cutting off a power supply path from the power source to the load side when the detected potential difference is larger than the reference voltage.

[Effect]

In the present invention, each discharge voltage of a plurality of rechargeable batteries connected in series is detected by the voltage detection means. The difference between the detected values is detected by the potential difference detection means. Each detected difference is compared with a preset reference voltage by a comparing means. Then, when the detected voltage difference is larger than the reference voltage, the power supply path is cut off by the cutoff means. Therefore, when the discharge voltages of the rechargeable batteries differ greatly in this way, the discharge operation of the batteries is stopped.

〔Example〕

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic block diagram of the power supply device of this example. As shown in this figure, the device 1 of this example is equipped with three rechargeable batteries A, B, and C connected in series as a power source, and the positive terminal of battery A, which is the positive terminal, supplies power. The lead wires that make up the road! 1 and a switch 14 interposed therebetween, it is connected to the positive input terminal 5 of the device. Further, the negative terminal of the battery C, which is the negative terminal thereof, is connected to the negative output terminal 16 of the device via a lead wire i2 forming a power supply path.

A differential amplifier 2 is connected in parallel to the rechargeable battery A.
The positive input terminal of the amplifier is connected to the positive side of battery A, and the negative input terminal of the amplifier is connected to the negative side of battery A. Similarly, a differential amplifier 3 is connected in parallel to rechargeable battery B, and the positive input terminal of the amplifier is connected to battery B.
The positive side of battery B is connected to the positive side of battery B, and its negative input terminal is connected to the negative side of battery B, respectively.

The output side of the differential amplifier 2 is connected to the positive input terminal of the next-stage differential amplifier 4 and the negative input terminal of the differential amplifier 5.
each connected. On the other hand, the input terminal on the other side of each differential amplifier 4.5 is connected to the negative input terminal of the differential amplifier 3 at the previous stage. Similarly, the output side of the differential amplifier 3 at the previous stage is connected to the positive input terminal of the differential amplifier 6 at the next stage and the negative input terminal of the differential amplifier 7, respectively. The input terminals on the other side of these differential amplifiers 6.7 are connected to the negative input terminal of the differential amplifier 3 at the previous stage.

Next, diodes 8 to 11 are connected in the forward direction to the output sides of the differential amplifiers 4 to 7, respectively, and the other side of these diodes is connected to the positive input terminal of the comparator 13. ing. A reference voltage Vc output from the potential setting section 12 is applied to the negative input terminal of this comparator. The output side of this comparator 3 is connected to the input side of the switch 14 described above.

This switch 14 is configured to be in a closed state while a low logic level signal is inputted, and, conversely, to be in an open state while a high logic level signal is inputted.

The discharge control operation of the device 1 having this configuration will be explained.

First, on the output side of the differential amplifier 2, there is a discharge voltage v to the battery.
1 appears. Further, the discharge voltage 1 of the rechargeable battery B appears on the output side of the differential amplifier 3.

On the other hand, the discharge voltage 3 of the rechargeable battery C appears at the negative input terminal of the differential amplifier 3. Therefore, the voltage V1 that is the output of the differential amplifier 2 appears at the positive input terminal of the next-stage differential amplifier 4.5, and the potential ■2 that is the output of the differential amplifier 3 appears at the next-stage differential amplifier 6.5. Appears at the positive input terminal of 7. Further, voltage V3 appears at the negative terminal of differential amplifier 4.6 and the positive terminal of differential amplifier 5.7, respectively.

As a result, a voltage difference between voltages ■1 and ■3 appears on the output side of the differential amplifier 4.5, and a voltage difference between voltages ■2 and ■3 appears on the output side of the differential amplifier 6.7. appears. Therefore, the voltages ■1 and ■2 are applied to the positive input of the comparator 13, which is obtained by wire-ORing these outputs via diodes.
, and the absolute difference between voltages 2 and V3, whichever is larger, is applied.

This voltage difference is compared with a reference voltage in a comparator 13, and if the voltage difference is smaller, a low logic level signal is outputted therefrom, and in the opposite case, a high logic level signal is outputted therefrom. This output signal is input to a switch 14 (for example, a p-channel MO3FET), and when this output signal is inverted from a low logic level to a high logic level, this switch 14 opens and the power supply path r1 is cut off.

In this way, in the power supply device 1 of this example, the voltage difference between the rechargeable batteries A and C connected in series or the battery B
, C exceeds a reference voltage value, the power supply path is automatically cut off to stop discharging the rechargeable battery. Therefore, it is possible to avoid discharging operations under such conditions where there is a large voltage difference, thereby preventing adverse effects such as a shortened lifespan of each rechargeable battery and liquid leakage that would otherwise occur due to such discharging operations. be able to.

In addition, in this example, between batteries A and C, and between batteries B,
Only the voltage difference between batteries A and B is detected, and discharge control is performed based on this, but in addition to this, the voltage difference between batteries A and B is also detected, and if this difference exceeds a certain level, discharge is also performed. By prohibiting this, undesired discharge can be more reliably avoided. In addition, in this example, a power source with three batteries connected in series is used, but the number of batteries is increased, and in response to the increase in the number of batteries, the differential amplifier in the previous stage and the differential amplifier in the next stage are By increasing the number of side differential amplifiers and forming circuit connections similar to those in this example, the present invention can be applied to a power supply circuit having a large number of batteries.

(Effects of the Invention) As explained above, the present invention provides a power supply device in which a plurality of rechargeable batteries are connected in series, and when the difference in discharge voltage of each battery is detected and this difference exceeds a predetermined value. Since the present invention is characterized in that it is provided with a discharge control circuit that stops power supply, it is possible to prevent a decrease in battery life and occurrence of liquid leakage due to a difference in discharge voltage of a rechargeable battery.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing a power supply device according to an embodiment of the present invention. [Explanation of symbols] ■... Power supply device 2.3, 4, 5, 6.7... Differential amplifier 8.9, 10
．． 11... Diode 12... Potential setting unit 13... Comparator 14... Switch 15.16... Output terminals A, B, C... Rechargeable battery. ! 1.12...Lead wire (power supply path).

Claims (1)

[Claims] In a power supply device using a plurality of rechargeable batteries connected in series as a power source, a voltage detection means for detecting the discharge voltage of the rechargeable batteries, and based on the output of the voltage detection means,
a potential difference detection means for detecting a potential difference between the rechargeable batteries; a comparison means for comparing the detected potential difference with a reference voltage; and when the detected potential difference is larger than the reference voltage by the comparison means, the What is claimed is: 1. A power supply device equipped with a discharge control circuit, comprising a cutoff means for cutting off a power supply path from a power source to a load side.