JPH0716290B2 - Device for converting absolute value of battery charge / discharge current into pulse width - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides an absolute value of a battery charging / discharging current for generating a pulse having a pulse width corresponding to an absolute value of a charging current or a discharging current flowing in a battery. It relates to a device for converting into.

[Conventional technology]

The absolute value of the battery charge / discharge current in a battery charge / discharge control device that detects the charge / discharge current that actually flows in the battery to obtain the charge / discharge capacity, remaining capacity, etc., and then controls the battery charge based on the results. To pulse width,
Various processing is performed using the pulse width.

Conventionally, as shown in FIG. 3, this type of converter is connected to a current detecting resistor 9 inserted in a battery charging / discharging current path, and has a positive voltage value or a negative voltage value depending on the battery charging / discharging current. Charge / discharge current detection circuit 1 that outputs a voltage value
And an analog absolute value amplifier 10 that outputs a positive voltage value according to the absolute value of the charging / discharging current by full-wave rectifying this output voltage, and a predetermined cycle, for example, 1/64 seconds, for example, 64 KHz
The counter 7 which starts the counting operation of the clock of 0 from the initial value zero, the unipolar type D / A converter 2 ′ which converts the count value of the counter 7 into the analog voltage value and converts it into the analog voltage value, It is composed of a comparator 3 for comparing the output voltage of the A converter 2'and the output voltage of the analog absolute value amplifier 10, and a pulse having a pulse width from the comparator 3 according to the absolute value of the battery charging / discharging current has a predetermined cycle. It was output every time.

In the figure, 5 is an AND circuit that passes a clock during the period in which a pulse is output from the comparator 3. As a result, the AND circuit 5 outputs the absolute value of the battery charging / discharging current every predetermined period. A corresponding number of clocks will be output and input to the clock terminal CLK of the capacity integration counter 8. The capacity integration counter 8 includes a charge / discharge determination unit 6
The count-up operation is performed when it is determined that the battery is in the charging state, and the count-down operation is performed when the battery is determined to be in the discharging state. Therefore, the count value of the capacity integrating counter 8 remains in the battery. The capacity will be displayed.

[Problems to be Solved by the Invention]

Conventionally, the absolute value of the battery charging / discharging current was converted into the pulse width by the above-mentioned configuration, but the charging / discharging current detection circuit 1
The following problems have been encountered since the configuration is adopted in which full-wave rectification is performed by connecting an analog absolute value amplifier in the latter stage.

(1) In general, since the analog absolute value amplifier uses a diode for rectification, the temperature characteristic of the amplifier itself is not good due to the fluctuation of the forward voltage drop due to the temperature change. For this reason, the temperature characteristics of the conversion device itself are also affected and deteriorate.

(2) Since one of the adjustment operations of the converter is gain adjustment when full-wave rectification of the analog absolute value amplifier is added, and this kind of gain adjustment is difficult, the overall adjustment operation becomes complicated and difficult.

The present invention solves such a conventional problem, and an object thereof is to reduce a battery charge / discharge current which does not require the use of an analog absolute value amplifier which causes deterioration of temperature characteristics and difficulty of adjustment work. An object is to provide a device for converting an absolute value into a pulse width.

[Means for Solving the Problems]

A device for converting the absolute value of the battery charge / discharge current of the present invention into a pulse width is, in order to achieve the above-mentioned object, a battery charge / discharge current detection circuit, and a counter for starting the counting of a clock for each predetermined period, A bipolar type D / A converter that converts the count value of this counter into an analog voltage, a comparator that compares the output voltage of this D / A converter with the output voltage of the detection circuit, and the input of the D / A converter. Of the output bits of the counter corresponding to zero amperes, the output of the bit whose value is inverted and the output of the comparator are input to the exclusive OR circuit.

[Operation] In the device for converting the absolute value of the battery charging / discharging current of the present invention into the pulse width, the detection circuit detects the battery charging / discharging current actually flowing through the battery and outputs the output voltage to one input of the comparator. In addition, the bipolar D / A converter
The count value of the counter that starts counting the clock at every predetermined cycle is converted to an analog voltage and added to the other input of the comparator, the comparator compares both voltages, and the exclusive OR circuit is the D / A converter. According to the absolute value of the battery charge / discharge current, the exclusive OR condition of the output of the comparator and the output of the bit whose value is inverted by zero amps of the output bits of the counter that becomes the input of Output a pulse of pulse width.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of an apparatus for converting an absolute value of a battery charge / discharge current into a pulse width according to the present invention. The same reference numerals as those in FIG. D / A converter 4 is an exclusive OR circuit. The present embodiment is different from the conventional example of FIG. 3 in that the analog absolute value amplifier 10 of FIG. 3 is removed and the output of the charge / discharge current detection circuit 1 is directly input to one input terminal of the comparator 3. , Unipolar type D / A in Fig. 3
The converter 2'is a bipolar type D / A converter 2
The exclusive logic in which the output of the bit whose value is inverted by zero amperes (0A) among the output bits of the counter 7 that is the input of the D / A converter 2 and the output of the comparator 3 are input The sum circuit 4 is provided before the AND circuit 5. If the counter 7 is an 8-bit counter, the value of the 0th bit to the 7th bit is input to the D / A converter 2, and the D / A converter 2 sets the count value of the counter 7 to 00 _HEX.
-5V when FF _HEX , + 5V when FF _HEX , 00 _HEX ~ FF
A voltage that changes linearly from -5V to + 5V is output during _HEX . Therefore, the count value of the counter 7 is 80 _HEX (100
00000), that is, when only the 7th bit is "1", a voltage of 0V is output, so the 7th bit is added to the exclusive OR circuit 4.

2 shows the input / output characteristics of the D / A converter 2 in FIG. 1 during the period from when the counter 7 starts counting the clock to when it reaches the maximum value, the output of the comparator 3, and 7 of the counter 7. FIG. 6 is a diagram showing a temporal change in the value of the bit and the output of the exclusive OR circuit 4, and the operation of the embodiment shown in FIG. 1 will be described below with reference to FIG.

When the counter 7 starts counting clocks at the start of a predetermined cycle and the count value gradually increases from 00 _HEX , the output voltage V ₂ of the D / A converter 2 is correspondingly increased.
Increases linearly as shown in FIG. Now, assuming that the battery is in a discharging state and the output voltage V ₁ of the charge / discharge current detection circuit 1 is at the level shown in FIG. 2, the period when the output voltage V 2 of the D / A converter ₂ is smaller than the output voltage V ₁ During,
The output of the comparator 3 is at low level as shown in FIG. 2, and becomes high level when the output voltage V ₂ of the D / A converter 2 exceeds the output voltage V ₁ .

On the other hand, when the output voltage V ₂ of the D / A converter 2 is equal to or greater than zero amps, the seventh bit value of the counter 7 as shown in FIG. 2 is changed from "0" to "1". Therefore, the output of the exclusive OR circuit 4 which receives the value of the 7th bit and the output of the comparator 3 is as shown in FIG. 2, and the output voltage V ₂ of the D / A converter ₂ is the charge / discharge current detection. A pulse having a high level is obtained during the period from when the output voltage V ₁ of the circuit 1 is exceeded to when it reaches 0V. And in this case D / A
Since the characteristic of the output voltage V ₂ of the converter 2 is linear, the pulse width of the pulse output from the exclusive OR circuit 4 depends on the absolute value of the battery charge / discharge current.

FIG. 2 shows the case where the battery is in the discharging state. However, when the battery is in the charging state, the charging / discharging current detection circuit 1
When the output voltage V ₁ of the above becomes larger than 0 V, the rising edge of the output waveform of the comparator 3 in FIG. 2 is shifted to the right rather than the rising edge of the waveform of the value of the 7th bit in FIG.
A pulse having a pulse width equal to the difference between the rising times is generated by the exclusive OR circuit 4 and also becomes a pulse having a pulse width corresponding to the absolute value of the battery charge / discharge current.

〔The invention's effect〕

As described above, in the device for converting the absolute value of the battery charging / discharging current of the present invention into the pulse width, the bipolar type D / A converter is used, and zero of the input bits of the D / A converter is used. The output of the battery charge / discharge current detection circuit can be directly input to the comparator by using the exclusive OR circuit that inputs the output of the bit whose value is inverted by ampere and the output of the comparator. it can. As a result, the analog absolute value amplifier required in the past becomes unnecessary, the deterioration of temperature characteristics and the difficulty of adjustment work, etc., which are caused by it, can be eliminated, and the structure becomes simple.

[Brief description of drawings]

 FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an operation explanatory diagram of an embodiment of the present invention, and FIG. 3 is a block diagram of a conventional example. In the figure, 1 ... Charge / discharge current detection circuit 2 ... Bipolar type D / A converter 2 '... Unipolar type D / A converter 3 ... Comparator 4 ... Exclusive OR circuit 5 ... Logical product Circuit 6 …… Charging / discharging judgment section 7 …… D / A converter counter 8 …… Capacity integrating counter 9 …… Current detection resistor 10 …… Analog absolute value amplifier

Claims (1)

[Claims] 1. A battery charging / discharging current detection circuit, a counter that starts counting clocks at predetermined intervals, a bipolar D / A converter that converts the count value of the counter into an analog voltage, and the D / A converter. A comparator that compares the output voltage of the A converter with the output voltage of the detection circuit, and the output of the bit whose value is inverted at zero amperes of the output bits of the counter that becomes the input of the D / A converter, and An apparatus for converting an absolute value of a battery charging / discharging current into a pulse width, including an exclusive OR circuit having an output of a comparator as an input.