JPH07107676A - Charge control method - Google Patents

Abstract

(57) [Summary] [Purpose] For charging from the start of charging to the maximum switching voltage of the secondary battery up to the set switching voltage, charge control is performed by voltage detection with a low-precision reference voltage source. Is characterized by performing constant voltage charging control by detecting a voltage with a highly accurate reference voltage source, thereby performing highly accurate constant voltage charging control with low power consumption. [Constitution] The constant voltage control circuit 6 inputs the output voltage (VB) of the secondary battery 1 and the output voltage of the comparator 5 (the output voltage according to the difference between the battery voltage and the reference voltage), and outputs them as values. , According to a preset switching voltage (VSW), the secondary battery 1 is controlled to charge at a constant voltage, and the switch 4 is controlled to be switched. When (VB <VSW), the low-precision reference voltage source 3 provides high accuracy. Switch the circuit to the reference voltage source 2 of
When ≧ VSW), the high-accuracy reference voltage source 2 is connected to the circuit to perform constant-voltage charging control by highly-accurate voltage detection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging control method for a secondary battery which requires constant voltage charging, and more particularly to a charging control method for suppressing the current consumption of a reference voltage source to reduce power consumption.

[0002]

2. Description of the Related Art Conventionally, in a charging circuit for a secondary battery which requires constant voltage charging control, when performing constant voltage charging control by a reference voltage source, it is possible to obtain from a single reference voltage source provided in the circuit. The secondary battery was charge-controlled based on the reference voltage value.

Here, in order to obtain a high charge capacity in a secondary battery that requires constant voltage charging, a high voltage that is less than the charge allowable voltage of the secondary battery and that is closest to the maximum voltage value is used. Needs to be charged.

However, since the reference voltage source actually has a variation in accuracy, the variation in accuracy must be taken into consideration.
The charging voltage is set low within the range that does not exceed the allowable charging voltage. At this time, the reference voltage source consumes power, and power consumption (current consumption) increases as the precision increases.

Further, in a circuit in which power is consumed by the reference voltage source even during discharge, it is necessary to use a reference voltage source with low power consumption (low accuracy) in order to improve discharge efficiency. However, as described above, as the characteristic of the reference voltage source, the higher the accuracy, the larger the power consumption (current consumption).

As described above, in the conventional charge control of the secondary battery requiring constant voltage charging, if the reference voltage source is made highly accurate, the power consumption (current consumption) becomes large, On the other hand, in order to suppress the power consumption, there is a problem that the reference voltage source must be set to low accuracy and the charging voltage must be set to be low.

[0007]

As described above, in the conventional charging control of the secondary battery requiring constant voltage charging, if the reference voltage source is made highly accurate, the power consumption (current consumption) becomes large. On the contrary, in order to suppress the power consumption, there is a problem that the reference voltage source must be set to low accuracy and the charging voltage must be set low.

The present invention has been made in view of the above circumstances,
In charge control of a secondary battery that requires constant voltage charging,
It is an object of the present invention to provide a charging control method capable of realizing a highly accurate and low power consumption constant voltage charging control mechanism.

[0009]

According to the present invention, charging from a start of charging to a certain voltage (hereinafter referred to as a switching voltage) approaching the maximum allowable voltage of the secondary battery is performed by a low-accuracy reference voltage source. A charge control mechanism that performs constant voltage charge control with low power consumption is realized by performing charge control by voltage detection and performing constant voltage charge control by voltage detection with a highly accurate reference voltage source after the switching voltage.

That is, according to the present invention, in charge control of a secondary battery requiring constant voltage charging, a high-precision reference voltage source serving as a reference of the output voltage (battery voltage) and a low-precision reference voltage. Power source, means for switching these reference voltage sources, and a constant voltage control circuit that detects the output voltage and controls the switching of the reference voltage source to control the constant voltage charging of the secondary battery. , The reference voltage source was switched according to the output voltage, and the maximum allowable voltage of the secondary battery was approached from the start of charging,
Up to a certain voltage (switching voltage), charge control is performed by voltage detection with a low-precision reference voltage source, and constant voltage charge control is performed by voltage detection with a high-precision reference voltage source after the switching voltage. In addition, high-precision constant voltage charging control with low power consumption is performed, including during discharging.

Further, the present invention provides an output voltage (battery voltage) for controlling charging of a secondary battery which requires constant voltage charging.
High-accuracy reference voltage source, which is the reference for low-precision reference voltage source, means for switching these reference voltage sources, output voltage detection and reference voltage source switching control, and rechargeable secondary battery with constant voltage A constant voltage control circuit for controlling is provided, and the constant voltage control circuit selectively operates one of the reference voltage sources according to the output voltage, the precision error range of the low precision reference voltage source, and the maximum allowable voltage of the secondary battery. The secondary battery is configured to perform constant voltage charging control, and the battery voltage for switching from the low-precision reference voltage source to the high-precision reference voltage source, even when the detected battery voltage value for performing this switching varies to the maximum value, It is characterized in that the power consumption is reduced by setting the voltage to the maximum allowable voltage at the time of charging, which is determined according to the type of battery.

Further, the present invention, in charge control of a secondary battery which requires constant voltage charging, has a reference voltage source whose accuracy changes according to power consumption which is a reference of the output voltage, and a reference voltage source which changes according to the output voltage. A constant voltage control circuit having control means for changing the power supplied to the reference voltage source by the constant voltage control circuit, the constant voltage control circuit controlling the supply power of the reference voltage source according to the output voltage, and the secondary battery according to the value of the reference voltage source. As a configuration for controlling the constant voltage charging,
It is characterized by performing high-precision constant voltage charging control with low power consumption, including during charging off and discharging.

Further, according to the present invention, in charge control of a secondary battery requiring constant voltage charging, a reference voltage source whose accuracy changes according to current consumption, which serves as a reference for the output voltage, and an output voltage are used. It is equipped with a constant voltage control circuit that controls the supply power of the reference voltage source to control the constant voltage charging of the secondary battery, and even when the output voltage varies to the maximum value, it is determined by the type of battery during charging. It is characterized in that low power is realized as a configuration for performing constant voltage charging control including during charging off and discharging so that the voltage becomes equal to or less than the maximum allowable voltage.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. First, referring to FIG. 1, a first embodiment of the present invention and a second embodiment
An example will be described. FIG. 1 is a block diagram showing a circuit configuration of a first embodiment and a second embodiment of the present invention.

In FIG. 1, reference numeral 1 is a secondary battery which requires constant voltage charging. Reference numeral 2 is a highly accurate reference voltage source, which requires large power consumption (current consumption). Reference numeral 3 is a low-precision reference voltage source, and its power consumption (current consumption) is small.

Reference numeral 4 denotes a switch for selecting a reference voltage source and connecting it to a circuit. The constant voltage control circuit 6 controls switching between the high precision reference voltage source 2 and the low precision reference voltage source 3. Reference numeral 5 is a comparator (COMP) that detects a difference between the battery voltage (output voltage) and the reference voltage, and compares the reference voltage obtained by the reference voltage source selected by the switch 4 with the output voltage of the secondary battery 1. Then, the difference voltage (detection voltage) is output.

Reference numeral 6 is a constant voltage control circuit for controlling the constant voltage charging of the secondary battery 1. In the first embodiment, the secondary battery 1 is used.
The constant voltage charging control is performed on the secondary battery 1 based on the output voltage of 1), the output of the comparator 5 (detection voltage), and a preset setting switching voltage. Also, in the second embodiment, the secondary battery 1
Of the output voltage of the comparator 5, the output (detection voltage) of the comparator 5, the preset switching voltage, the accuracy error range of the low-accuracy reference voltage source 3, and the maximum allowable voltage of the secondary battery 1. The secondary battery 1 is controlled by constant voltage charging.

The operation of the first and second embodiments of the present invention will be described with reference to FIG. (First Embodiment) First, the operation of the first embodiment will be described with reference to FIG.

Here, the battery voltage of the secondary battery 1 is VB
(V), and the set switching voltage is VSW (V).
The secondary battery 1 requires constant voltage charge control during charging.

The comparator 5 has a battery voltage for checking obtained by dividing the output (VB) of the secondary battery 1 with a fixed resistor and a reference voltage source (high voltage selected by the constant voltage control circuit 6 and connected to the circuit. The difference with the reference voltage obtained by the precision reference voltage source 2 or the low precision reference voltage source 3) is compared and sent to the constant voltage control circuit 6.

The constant voltage control circuit 6 inputs the output voltage (VB) of the secondary battery 1 and the output voltage of the comparator 5, and according to the values and the preset switching voltage (VSW), the secondary voltage The battery 1 is subjected to constant voltage charging control.

That is, at the start of charging, the low-precision reference voltage source 3 is connected to the circuit, and [VB <VSW] from the start of charging.
Up to, the voltage detection is performed based on the reference voltage value by the low-precision reference voltage source 3.

The switch 4 switches the circuit from the low-accuracy reference voltage source 3 to the high-accuracy reference voltage source 2 when [VB <VSW], and when [VB ≧ VSW], the voltage is set with the high-accuracy reference voltage source 2 as a reference. Detection is performed.

Under the condition of [VB ≧ VSW],
High-accuracy constant-voltage charging control using the high-accuracy reference voltage source 4 is performed on the secondary battery 1. When the secondary battery 1 is discharged, the power consumption is suppressed by switching to the low-accuracy reference voltage source 3 (the low-accuracy reference voltage source 3 is circuit-connected).

(Second Embodiment) Next, a second embodiment will be described with reference to FIG. Here, the output voltage (battery voltage) of the secondary battery 1 is VB (V), the set switching voltage is VSW (V), the precision of the low precision reference voltage source 3 is α (V),
The maximum allowable voltage of the secondary battery 1 is VBMAX.

The secondary battery 1 requires constant voltage charging control during charging. The comparator 5 is obtained by the output voltage (battery voltage) of the secondary battery 1 and a reference voltage source (high precision reference voltage source 2 or low precision reference voltage source 3) selected by the constant voltage control circuit 6 and connected in the circuit. The difference between the reference voltage and the reference voltage is compared and sent to the constant voltage control circuit 6.

The constant voltage control circuit 6 inputs the output voltage of the secondary battery 1 and the output voltage of the comparator 5, and according to these values and a preset switching voltage (VSW), the secondary battery 1
Constant voltage charging control.

That is, at the start of charging, the low-accuracy reference voltage source 3 is connected to the circuit, and [VB
Until <VSW], voltage detection is performed using the low-precision reference voltage source 3 as a reference voltage value.

The switch 4 [VB = VSW] switches the circuit from the low-precision reference voltage source 3 to the high-precision reference voltage source 4. Here, the reference voltage source 3 has accuracy, and the reference voltage varies up to VB + α. Therefore, [VB + α ≤ VBMA
X], the switching voltage (VSW) of the switch 4 is set to [VSW = VBMAX−α].

Under the condition of [VB ≧ VSW],
High-accuracy constant-voltage charging control using the high-accuracy reference voltage source 4 is performed on the secondary battery 1. When the secondary battery 1 is discharged, the power consumption is suppressed by switching to the low-accuracy reference voltage source 3 (the low-accuracy reference voltage source 3 is circuit-connected).

Next, referring to FIG. 2, the third and fourth embodiments of the present invention will be described. FIG. 2 is a block diagram showing the circuit configurations of the third and fourth embodiments of the present invention.

In FIG. 2, reference numeral 21 is a secondary battery which requires constant voltage charging. Reference numeral 22 denotes a reference voltage source, the accuracy of which changes with changes in the supplied power. The larger the supplied power, the larger the current consumption and the higher the accuracy.

Reference numeral 23 is a comparator (COMP) for detecting the difference between the battery voltage (output voltage) and the reference voltage, and compares the reference voltage obtained by the reference voltage source 22 with the output voltage of the secondary battery 21, The voltage of the difference (detection voltage) is output.

Reference numeral 24 is a constant voltage control circuit for controlling the constant voltage charging of the secondary battery 21, and in the third embodiment, the output voltage of the secondary battery 21 and the output (detection voltage) of the comparator 23.
Then, the power supply to the reference voltage source 22 is controlled on the basis of the predetermined setting switching voltage, and the secondary battery 21 is controlled to be constant-voltage charged by the reference voltage value with accuracy according to the power supply. In addition, in the fourth embodiment, the output voltage of the secondary battery 21, the output (detection voltage) of the comparator 23, the preset switching voltage, and the accuracy of the reference voltage source 22 with low accuracy. Error range (α) and maximum allowable voltage of secondary battery 21 (VBM
AX) and the secondary battery 21 is subjected to constant voltage charging control.

The operation of the third and fourth embodiments of the present invention will be described with reference to FIG. (Third Embodiment) First, the operation of the third embodiment will be described with reference to FIG.

Here, the battery voltage of the secondary battery 21 is VB
(V), and the set switching voltage is VSW (V).
The comparator 23 compares the difference between the output voltage (battery voltage) of the secondary battery 21 and the reference voltage and sends it to the constant voltage control circuit 24.

The constant voltage control circuit 24 inputs the output voltage of the secondary battery 21 (battery voltage is VB) and the output voltage of the comparator 23, and outputs those values and a preset switching voltage (V
SW), the secondary battery 21 is controlled for constant voltage charging, and the power supplied to the reference voltage source 22 is controlled. That is,
The constant voltage control circuit 24 supplies electric power to the reference voltage source 22 based on the output voltage of the secondary battery 21, the output (detection voltage) of the comparator 23, and a preset setting switching voltage (VSW). Is controlled, and the secondary battery 21 is subjected to constant voltage charging control with a reference voltage value having an accuracy according to the supplied power.

Here, the reference voltage source 22 becomes highly accurate when the supplied power is large, and switches to the low accuracy when the supplied power is suppressed. The constant voltage control circuit 24 suppresses the power supplied to the reference voltage source 22 at the start of charging to be small, and
2 is set to low precision, and charge control is performed with low precision during the period of [VB <VSW] from the start of charging.

When [VB = VSW] is reached, the constant voltage control circuit 24 increases the power supplied to the reference voltage source 22 and switches the accuracy from low accuracy to high accuracy. This [VB ≧ VS
[W] performs charge control with high accuracy.

At the time of discharging, the reference voltage source 22 is switched with low accuracy to suppress power consumption. (Fourth Embodiment) Next, a fourth embodiment will be described with reference to FIG.

Here, the output voltage (battery voltage) of the secondary battery 21 is VB (V), the switching voltage is VSW (V), the maximum allowable voltage of the secondary battery 21 is VBMAX (V), and the reference voltage source 2
The accuracy at the low accuracy of 2 is α (V).

The secondary battery 21 requires constant voltage charging control during charging. The comparator 23 compares the difference between the battery voltage and the reference voltage and sends it to the constant voltage control circuit 24.

The constant voltage control circuit 24 outputs the output voltage (VB) of the secondary battery 21 and the output voltage (detection voltage) of the comparator 23.
Then, the secondary battery 21 is determined based on the preset switching voltage (VSW), the accuracy (α) of the reference voltage source 22 with low accuracy, and the maximum allowable voltage (VBMAX) of the secondary battery 21. The voltage charging is controlled, and the power supplied to the reference voltage source 22 is controlled.

Here, the reference voltage source 22 becomes highly accurate when the supplied power is large, and switches to the low accuracy when the supplied power is suppressed. The constant voltage control circuit 24 suppresses the electric power supplied to the reference voltage source 22 at the start of charging to be small, and
The accuracy of is reduced, and the charging is performed with low accuracy in the period of [VB <VSW] from the start of charging.

When [VB = VSW], the constant voltage control circuit 24 increases the power supplied to the reference voltage source 22 and switches the precision of the reference voltage source 22 from low precision to high precision. Here, the reference voltage of the reference voltage source 22 varies to the maximum [VB + α] due to the accuracy accompanying the consumption current of the reference voltage source 22. In this kind of charge control, it is necessary to satisfy [VB + α ≦ VBMAX], so [VSW ≦ VBMAX−α].

When [VB ≧ VSW], the charge control is performed with high accuracy. At the time of discharging, the power supply of the reference voltage source 22 is suppressed to switch the reference voltage source 22 with low accuracy, and the power consumption is suppressed.

By the accuracy switching control of the reference voltage source as described above, charging can be controlled at a high charging voltage suitable for the characteristics of the secondary battery at the time of charging, so that the charging capacity is large, and at the time of discharging, the discharging efficiency is high. Therefore, the battery life of the equipment used can be extended.

[0048]

As described above in detail, according to the present invention, it is possible to realize a constant voltage charging control mechanism with high accuracy and low power consumption in charging control of a secondary battery which requires constant voltage charging.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a first embodiment and a second embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration of a third embodiment and a fourth embodiment of the present invention.

[Explanation of symbols]

1, 21 ... Secondary battery, 2, 3, 22 ... Reference voltage source (2 ...
High precision reference voltage source, 3 ... Low precision reference voltage source, 22 ...
Reference voltage source whose accuracy varies depending on the supplied power), ... Switches, 5, 23 ... Comparator (COMP), 6, 24 ... Constant voltage control circuit.

Claims (4)

[Claims] 1. A first reference voltage source for obtaining a highly accurate reference voltage value which is a reference of a battery output voltage in charge control of a secondary battery which requires constant voltage charging, and a reference voltage source A second reference voltage source for obtaining a low-precision reference voltage value, a reference voltage source switching means for selecting one of the reference voltage sources, the battery output voltage is measured, and according to the measured output voltage and the setting switching voltage. And a constant voltage control circuit for controlling a constant voltage charging of the secondary battery based on the voltage value of the selected reference voltage source by switching the reference voltage source switching means. A charging control method characterized in that one of the reference voltage sources is selectively operated in accordance with the voltage and the set switching voltage to control the rechargeable battery at a constant voltage. 2. A first reference voltage source that obtains a highly accurate reference voltage value that serves as a reference for a battery output voltage in charge control of a secondary battery that requires constant voltage charging, and the reference voltage source. A second reference voltage source for obtaining a low-accuracy reference voltage value, reference voltage source switching means for selecting one of the reference voltage sources, and measurement of the battery output voltage for switching control of the reference voltage source switching means. A constant voltage control circuit for controlling the constant voltage charging of the secondary battery based on the voltage value of the reference voltage source selected by the constant voltage control circuit, wherein the constant voltage control circuit controls the measured output voltage and the second reference voltage source. A charging control method characterized in that one of the reference voltage sources is selectively operated in a circuit according to the accuracy error range and the maximum allowable voltage of the secondary battery to control the constant voltage charging of the secondary battery. 3. In charge control of a secondary battery that requires constant voltage charging, a reference voltage source whose consumption current and accuracy change by changing the supplied power, and a secondary voltage by measuring the battery output voltage. A constant voltage control circuit for controlling constant voltage charging of the battery, wherein the constant voltage control circuit controls the supply power of the reference voltage source according to the measured output voltage, and the constant voltage of the secondary battery according to the value of the reference voltage source. A charge control method characterized by charge control. 4. In charge control of a secondary battery requiring constant voltage charging, a reference voltage source whose consumption current and accuracy change by changing the supply power, and a battery output voltage are measured, and the measurement is performed. A constant voltage control circuit for controlling the supply power of the reference voltage source according to the output voltage to control the constant voltage charging of the secondary battery, wherein the constant voltage control circuit has an accuracy error between the measured output voltage and the reference voltage source. A charging control method characterized by performing constant voltage charging control of a secondary battery according to a range and a maximum allowable voltage of the secondary battery.