JP2006177782A - Voltage measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage measuring device capable of measuring accurately a voltage in a specific voltage range having the narrower width than the width of a reference voltage range of a reference voltage of an AD converter to be used within an output voltage range of a power source which is a measuring object. <P>SOLUTION: This voltage measuring device 1 for measuring the voltage in the specific voltage range having the narrower width than the width of the reference voltage range of the reference voltage Vref of the AD converter 3 to be used within the output voltage range of the power source B which is the measuring object, includes a cutting-out circuit 5 for cutting out the specific voltage range from within the output voltage range of the power source B and outputting the voltage in the specific voltage range, an amplifying circuit 7 for amplifying the specific voltage range cut out by the cutting-out circuit 5 so as to correspond to the reference voltage range of the reference voltage Vref, and the AD converter 3 for determining an AD converted value of a supply voltage inputted into the cutting-out circuit 5 from the voltage transformed corresponding to amplification of the specific voltage range by the amplifying circuit 7. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a voltage measuring device that measures the voltage of a power source such as a battery.

  In recent years, in order to accurately detect the state of charge of a vehicle battery (the voltage of the generator when the engine is running and its upper limit voltage is about 17 V), a specific voltage range (voltage measurement) within the battery output voltage range is detected. A voltage within a specific voltage range (for example, 11.5 V to 13.0 V) narrower than the reference voltage range (for example, 0 V to 5 V) of the reference voltage of the AD converter of the apparatus (for example, a measurement error of about 20 mV). Is required to be measured (within accuracy).

  As conventional voltage measuring apparatuses, there are the following two voltage measuring apparatuses (first conventional example and second conventional example).

  As shown in FIG. 6, for example, the voltage measuring device 100A of the first conventional example uses the output voltage range (for example, 0V to 17V) of the battery B as the reference voltage range (0V to 5V), and a voltage that is lower than the reference voltage Vref of the AD converter 103 from the voltage range of the output voltage of the voltage dividing conversion circuit 105. A cut-out circuit (part consisting of a Zener diode D10) 107 that cuts out the range and an AD converter 103 that obtains an AD conversion value of the output voltage of the battery B from the output voltage of the cut-out circuit 107 are configured.

  That is, the voltage measuring apparatus 100A performs voltage division (reduction) conversion so that the entire range of the output voltage range of the battery B corresponds to the reference voltage range of the reference voltage Vref of the AD converter 103. The range is configured to be the entire range of the output voltage range of the battery B.

  On the other hand, the voltage measuring apparatus 100B of the second conventional example cuts out a voltage range equal to or higher than a predetermined lower limit voltage from the output voltage range (for example, 0V to 17V) of the battery B as shown in FIG. A first cut-out circuit (part consisting of a Zener diode D20) 107a for inputting a battery voltage, and a voltage-dividing conversion circuit (resistor R10) for voltage-dividing and converting the voltage range of the output voltage of the first cut-out circuit 107a to a predetermined voltage range , R20) 105 and a second cut-out circuit (a Zener diode D10) that cuts out a voltage range equal to or lower than the reference voltage Vref (for example, 5 V) of the AD converter 103 from the voltage range of the output voltage of the voltage dividing conversion circuit 105 (Part) 107b and an AD converter 103 for obtaining an AD conversion value of the output voltage of the battery B from the output voltage of the second cut-out circuit 107b.

  That is, the voltage measuring device 100B is simply wider than the reference voltage range of the reference voltage Vref of the AD converter 103 from the output voltage range of the battery B by the first and second cut-out circuits 107a and 107b. The specific voltage range of the width is cut out, and the specific voltage range is divided (reduced) by the voltage dividing conversion circuit 105 so as to correspond to the reference voltage range of the reference voltage Vref, whereby the measurement voltage range is specified. The specific voltage range can be measured with high accuracy by limiting the voltage range.

  In the voltage measuring apparatus 100A of the first conventional example, the measured voltage range is as wide as the entire output voltage range of the battery B. Therefore, as in the present application, the width of the reference voltage range of the reference voltage Vref of the AD converter 103 is as follows. When trying to measure a specific voltage range having a narrower width, the AD resolution of the AD converter 103 is too low (that is, the measurement error due to the AD resolution is too large), and there is a drawback that it cannot be accurately measured with the required accuracy. .

  In general, the wider the measurement voltage range, the larger the measurement error due to the reference voltage error of the AD converter. However, the measurement voltage range is the output voltage of the battery B as in the voltage measuring device 100A of the first conventional example. When the entire range is wide, the measurement error due to the error of the reference voltage Vref of the AD converter 103 becomes large, which is also the reason that the specific voltage range cannot be measured with high accuracy.

  In general, the AD conversion error and the error of the reference voltage Vref vary depending on the temperature and AD conversion timing, and it is difficult to correct the measurement error completely. In order to accurately measure the power supply voltage, It is necessary to minimize the influence of the AD conversion error and the reference voltage Vref.

  Actually, in the voltage measuring apparatus 100A of the first conventional example, for example, the output voltage range of the battery B is set to 0V to 17V, the reference voltage Vref is set to 5V (therefore, the reference voltage range is set to 0V to 5V), and the AD converter 103 The number of bits of the AD resolution is 10 bits, the measurement voltage range of the voltage measuring device 100A is the entire output voltage range of the battery B (0V to 17V), and the specific voltage range to be measured is 11.5V to 13.0V The measurement error due to the AD resolution of the AD converter 103 and the measurement error due to the error of the reference voltage Vref are calculated as follows.

  That is, the measurement error due to the AD resolution includes the AD resolution (in this case, the measurement voltage range of 0V to 17V is measured by 10 bits, which is about 17 mV / LSB), and the AD conversion error (for example, ± 3LSB) of the AD converter 103. Therefore, it is ± 51 mV. Further, the measurement error caused by the error of the reference voltage Vref is the output voltage (12V) of the battery B when the output voltage of the battery B is, for example, 12V within the specific voltage range (11.5V to 13.0V). And the error of the reference voltage Vref (for example, ± 1%), it is ± 120 mV. The measurement error of the voltage measuring apparatus 100A is 51 mV + 120 mV = 171 mV, and the measurement error due to these AD conversions alone is not within about 20 mV (actually, due to variations in the circuit elements R10 and R20). Since there is also a measurement error, the measurement error of the voltage measuring apparatus 100A is actually larger). From these calculation results, the voltage measuring apparatus 100A has a specific voltage range having a width narrower than the width of the reference voltage range (for example, 0V to 5V) of the reference voltage Vref in the output voltage range (for example, 0V to 17V) of the battery B. It can be seen that a voltage within (for example, 11.5 to 13.0 V) cannot be measured with high accuracy (for example, with a measurement error within about 20 mV).

  On the other hand, in the voltage measuring device 100B of the second conventional example, the measured voltage range is limited to a specific voltage range within the output voltage range of the battery B, and the AD converter 103 is used as the specific voltage range. Since a voltage range wider than the width of the reference voltage range of the reference voltage Vref of the AD converter 103 is assumed, a specific voltage having a width narrower than the width of the reference voltage range of the reference voltage Vref of the AD converter 103 is assumed. When trying to measure the range, the resolution of the AD converter 103 is still too low, and there is a drawback that it cannot be measured with high accuracy (for example, with accuracy within about 20 mV of measurement error).

  As described above, the measurement error due to the error of the reference voltage Vref increases as the measurement voltage range increases. However, the measurement voltage range of the voltage measurement device 100B of the second conventional example is the width of the reference voltage range of the reference voltage Vref. Since it is wider than the specific voltage range to be measured (the specific voltage range having a width narrower than the width of the reference voltage range of the reference voltage Vref), the measurement error caused by the error of the reference voltage Vref is excessively wide. This is the reason why the specific voltage range cannot be measured with high accuracy.

  Actually, in the voltage measuring apparatus 100B of the second conventional example, for example, the output voltage range of the battery B is set to 0V to 17V, and the resistors R10 and R20 are set to 100Ω and 50kΩ, respectively (in this case, the voltage dividing ratio is 0.998 and almost equal). The voltage of the Zener diodes D10 and D20 is 5V and 10V, the reference voltage Vref is 5V (therefore, the reference voltage range is 0V to 5V), and the AD converter 103 has an AD resolution bit. When the number is 10 bits and the specific voltage range to be measured is 11.5 V to 13.0 V, the measurement error due to the AD resolution of the AD converter 103 and the measurement error due to the error of the reference voltage Vref are calculated. Then it becomes as follows. Under this numerical setting, the measurement voltage range of the voltage measuring device 100B is approximately 10V to 15V.

  In other words, the measurement error due to the AD resolution includes the AD resolution (in this case, the measurement voltage range of approximately 10V to 15V is measured with 10 bits, and is approximately 5 mV / LSB), and the AD conversion error (for example, ±±). 3LSB), which is ± 15 mV. Further, the measurement error caused by the error of the reference voltage Vref is the output voltage (12V) of the battery B when the output voltage of the battery B is, for example, 12V within the specific voltage range (11.5V to 13.0V). Is calculated by the product of the amount (2V) included in the measured voltage range (10V to 15V) and the error (for example, ± 1%) of the reference voltage Vref, so that ± 20 mV. The measurement error of the voltage measuring apparatus 100 is only 15 mV + 20 mV = 35 mV due to the measurement error due to these AD conversions, and does not fall within the required measurement error of about 20 mV (in practice, circuit elements (resistors R10, R20 and Zener). Since there is also a measurement error due to variations in the diodes D20, D10), the measurement error of the voltage measuring device 100B is actually larger). From these calculation results, the voltage measuring apparatus 100B is narrower than the width of the reference voltage range (for example, 0V to 5V) of the reference voltage Vref of the AD converter 103 in the output voltage range (for example, 0V to 17V) of the battery B. It can be seen that a specific voltage range of width (for example, approximately 11.5 V to 13.0 V) cannot be measured with high accuracy (for example, with accuracy within about 20 mV of measurement error).

  Therefore, an object of the present invention is to accurately measure a voltage within a specific voltage range having a width narrower than the width of the reference voltage range of the reference voltage of the AD converter to be used in the output voltage range of the power source to be measured. The object is to provide a voltage measuring device.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a specific voltage having a width narrower than the width of the reference voltage range of the reference voltage of the AD converter used in the output voltage range of the power supply to be measured. A voltage measuring device for measuring a voltage within a range, wherein the specific voltage range is cut out from the output voltage range of the power source and a voltage within the specific voltage range is output, and the cut out circuit cuts out the specific voltage range. An amplification circuit that amplifies the specified voltage range so as to correspond to a reference voltage range of the reference voltage, and from the voltage transformed corresponding to amplification of the specific voltage range by the amplification circuit, to the extraction circuit The AD converter for obtaining an AD conversion value of the input power supply voltage.

  According to a second aspect of the present invention, the voltage values of a plurality of preset known voltages and the plurality of values obtained by AD conversion by the AD converter, which are input in advance through the cut-out circuit and the amplifier circuit. And a correction means for performing correction to remove a measurement error included in the AD conversion value of the power supply voltage obtained by the AD converter using the AD conversion value of the known voltage.

  According to the first aspect of the present invention, a specific voltage range having a width narrower than the width of the reference voltage range of the reference voltage of the AD converter is cut out from the output voltage range of the power supply, and the specific voltage range is extracted from the reference voltage range. (1) Voltage measurement can be performed with a relatively high AD resolution even for a specific voltage range narrower than the width of the reference voltage range, thereby resulting in the AD resolution. Measurement error can be reduced, and (2) the measurement voltage range can be prevented from becoming wider than the specific voltage range to be measured, thereby reducing the measurement error caused by the reference voltage error of the AD converter, From these (1) and (2), the voltage within a specific voltage range narrower than the width of the reference voltage range of the reference voltage of the AD converter to be used is accurately measured in the output voltage range of the power source to be measured. so That.

  According to the second aspect of the present invention, the voltage values of a plurality of known voltages that are set in advance and the plurality of voltages that are obtained through AD conversion by an AD converter that are input in advance through a cut-out circuit and an amplifier circuit. Since the correction for removing the measurement error included in the AD conversion value of the power supply voltage obtained by the AD converter is performed using the AD conversion value of the known voltage, the measurement error and the reference voltage error caused by the AD resolution are performed. In addition to the measurement error caused by the measurement error, the measurement error caused by the circuit element can be reduced, and the voltage within the specific voltage range can be measured with higher accuracy.

<Embodiment>
As shown in FIG. 1, the voltage measuring apparatus 1 according to this embodiment uses, for example, a vehicle battery (power supply) B as a measurement target, and uses the output voltage range (for example, 0 V to 17 V) of the battery B. The voltage within a specific voltage range (for example, 11.5 V to 13.0 V) having a width narrower than the width of the reference voltage range (0 to 5 V) of the reference voltage Vref (for example, 5 V) of the AD converter 3 is measured. . The voltage measuring apparatus 1 includes a terminal T that is detachably connected to the output terminal of the battery B, and a cutout that outputs the battery voltage within the specific voltage range by cutting out the specific voltage range from the output voltage range of the battery B. The circuit 5, the amplification circuit 7 that amplifies the specific voltage range cut out by the cutting circuit 5 so as to correspond to the reference voltage range of the reference voltage Vref, and the amplification of the specific voltage range by the amplification circuit 7 And an AD converter 3 for obtaining an AD conversion value of the battery voltage input to the extraction circuit 5 based on the transformed battery voltage. That is, the voltage measuring device 1 is configured such that the measured voltage range matches the specific voltage range to be measured.

  Here, the cut-out circuit 5 shifts the cut-out specific voltage range so that the lower limit voltage becomes 0 V, and then outputs it to the amplifier circuit 7. The amplifier circuit 7 is thus voltage-shifted. The specific voltage range is amplified so as to correspond to the reference voltage range of the reference voltage Vref.

  The cut-out circuit 5 includes Zener diodes D1 and D2 and resistors R1 and R2. Zener diode D1 is connected to terminal T in the reverse direction. The resistor R1 is connected between the Zener diode D1 and the ground point. The resistor R2 is connected between an intermediate point between the circuit elements D1 and R1 and a + input terminal T + of an operational amplifier P described later of the amplifier circuit 7. The Zener diode D2 is connected in the reverse direction between an intermediate point between the + input terminal T + and the resistor R2 and the ground point.

  In this cutting circuit 5, a Zener diode D1 cuts out a first voltage range (11.5V to 17V) equal to or higher than the Zener voltage (for example, 11.5V) from the output voltage range (0V to 17V) of the battery B. Only the battery voltage within the first voltage range is output. The voltage within the first voltage range thus cut out is shifted by the resistor R1 so that the lower limit voltage (11.5V) of the first voltage range is shifted to 0V. That is, the resistor R1 shifts the voltage of the first voltage range (11.5V to 17V) to the second voltage range (0V to 5.5V) with 0V as the lower limit voltage. The third voltage range (0V to 1.5V) below the Zener voltage (for example, 1.5V) from the second voltage range (0V to 5.5V) obtained by shifting the voltage by the Zener diode D2. Is cut out, and only the voltage within the third voltage range is output to the + input terminal T + of the operational amplifier P of the amplifier circuit 7. That is, roughly speaking, in this cutting-out circuit 5, as shown in FIG. 2, a specific voltage range (11.5V to 13.0V) from the output voltage range (0V to 17V) of the battery B by the Zener diodes D1 and D2 is used. ) Is cut out and only the battery voltage within the specific voltage range is input, and the voltage within the specific voltage range (11.5V to 13.0V) is within the third voltage range (0V to 1.5V) by the resistor R1. The voltage is shifted to this voltage and output to the amplifier circuit 7.

  The amplifier circuit 7 includes an operational amplifier P and resistors R3 and R4. The operational amplifier P has its + input terminal T + connected between the circuit elements R2 and D2, its − input terminal T− connected to the ground via a resistor R3, and its output terminal Tout being the input of the AD converter 3. It is connected to the terminal Tin and connected to its -input terminal T- through a resistor R4.

  In the amplifier circuit 7, as shown in FIG. 2, the third voltage range (0V to 1.5V) obtained by the voltage shift by the operational circuit P is extracted by the operational circuit P. The reference voltage range of the reference voltage Vref (0V to 1.5V) is obtained. 0V to 5V) (ie, the lower limit voltage 0V (upper limit voltage 1.5V) of the third voltage range corresponds to the lower limit voltage 0V (upper limit voltage 5V) of the reference voltage range of the reference voltage Vref). Then, the transformed battery voltage corresponding to the amplification of the third voltage range is output from the output terminal Tout to the input terminal Tin of the AD converter 3.

  The AD converter 3 is configured to be built in, for example, the CPU 9. The AD converter 3 has a function of AD converting a voltage within the reference voltage range (0V to 5V) of the reference voltage Vref input to the input terminal Tin with an AD resolution of a predetermined number of bits (for example, 10 bits). . Here, the reference voltage range (0 V to 5 V) of the reference voltage Vref includes a specific voltage range (11.5 V to 13.0 V) within the output voltage range (0 V to 17 V) of the battery B by the circuits 5 and 7. Since it is cut out, amplified, and associated, the voltage within the specific voltage range (11.5 V to 13.0 V) within the output voltage range (0 V to 17 V) of the battery B is converted by the AD converter 3 into the predetermined bit. AD conversion is performed with several AD resolutions.

  The measurement error (measurement error caused by the AD resolution and measurement error caused by the error of the reference voltage Vref) of the voltage measurement apparatus 1 configured in this way is set under the above numerical setting (that is, the output voltage range of the battery B). Is set to 0V to 17V, the specific voltage range (that is, the measurement voltage range) is set to 11.5V to 13.0V, the reference voltage Vref is set to 5V (therefore, the reference voltage range is set to 0V to 5V), and the AD resolution of the AD converter 3 is The calculation is as follows when the number of bits is 10 bits.

  That is, the measurement error caused by the AD resolution is the AD resolution (in this case, the measurement voltage range of 11.5 V to 13.0 V is measured with 10 bits, and thus is about 1.5 mV / LSB) and the AD converter 3 AD. Since it is calculated as a product of a conversion error (for example, ± 3LSB), it is ± about 4.5 mV. In addition, the measurement error due to the error of the reference voltage Vref is, of the output voltage (12V) of the battery B, when the output voltage of the battery B is, for example, 12V within the measurement voltage range (11.5V to 13.0V). Is calculated by the product of the amount included in the measured voltage range (11.5V to 13.0V) (0.5V) and the error of the reference voltage Vref (for example, ± 1%). Become. Therefore, the measurement error resulting from AD conversion of the voltage measuring apparatus 1 is the sum of these measurement errors, and therefore, 4.5 mV + 5 mV = 9.5 mV, which is within the required measurement error of 20 mV. From these calculation results, the voltage measuring apparatus 1 is narrower than the width of the reference voltage range (for example, 0V to 5V) of the reference voltage Vref of the AD converter 103 in the output voltage range (for example, 0V to 17V) of the battery B. It can be seen that a specific voltage range of width (for example, approximately 11.5 V to 13.0 V) can be measured with high accuracy (for example, with accuracy within about 20 mV of measurement error).

  According to the voltage measuring apparatus 1 configured as described above, the width of the reference voltage range (for example, 0V to 5V) of the reference voltage Vref of the AD converter 3 from the output voltage range (for example, 0V to 17V) of the battery B is determined. A specific voltage range having a narrow width (for example, 11.5 V to 13.0 V) is cut out, and the specific voltage range is amplified and measured so as to correspond to the reference voltage range. Therefore, (1) the reference voltage Vref Voltage can be measured with a relatively high AD resolution even for a specific voltage range narrower than the width of the reference voltage range, thereby reducing measurement errors due to AD resolution and (2) measuring the measurement voltage range Thus, it is possible to prevent a measurement error caused by an error in the reference voltage Vref of the AD converter 3 from being reduced, and from these (1) and (2), the measurement error can be reduced. Of the output voltage range of the battery B to elephants, voltage within a specific voltage range narrower than the width of the reference voltage range of the reference voltage Vref of the AD converter 3 used it can be accurately measured.

<Modification>
As shown in FIG. 3, the voltage measuring device 1 </ b> B according to this modification is further provided with a known voltage value (a voltage not including a measurement error) of a plurality of preset voltages (here, two) in the above-described embodiment. Value) (for example, V1, V2) and AD conversion values (voltage values including measurement errors) of the plurality of known voltages, which are input in advance through the circuits 5 and 7 and AD-converted by the AD converter 3. (For example, AD1, AD2) is used to correct the measurement error included in the AD conversion value ADbat of the output voltage of the battery B obtained by the AD converter 3, and thereby the measurement error with respect to the output voltage of the battery B And a storage device (for example, EEPROM) 13 for storing the known voltage values V1 and V2 of the plurality of known voltages and the AD conversion values AD1 and AD2. Constructed. Here, the correction circuit 11 is built in the CPU 9.

  The voltage measurement apparatus 1B has a fixed procedure in a measurement mode in which normal voltage measurement is performed by an external operation, for example, and a setting mode in which the AD conversion values AD1 and AD2 of the plurality of known voltages are stored in the storage device 13. It is configured to be switched by swallowing.

  In the above setting mode, the voltage measuring device 1B has the known voltage values V1 and V2 included in the measurement voltage range (for example, 11.5V to 13.0V) of the voltage measuring device 1B at the terminal T as shown in FIG. When the constant voltage power supplies B1 and B2 that output voltage are sequentially connected, the output voltage from the amplifier circuit 7 obtained from the input terminal Tin according to each connection (that is, the output voltage from each constant voltage power supply B1 and B2) AD conversion values AD1 and AD2 are obtained in the same manner as in the above embodiment, and the obtained AD conversion values AD1 and AD2 are associated with the known voltage values V1 and V2 preset in the storage device 13, respectively. And stored in the storage device 13. As a result, the AD conversion values AD 1 and AD 2 of the plurality of known voltages are set in the storage device 13.

  Further, in the above measurement mode, when the battery B is connected to the terminal T in the above measurement mode, the voltage measuring device 1B outputs the output voltage (from the amplifier circuit 7 obtained from the input terminal Tin in accordance with the connection (see FIG. 3). That is, the AD conversion value ADbat of the output voltage from the battery B is obtained in the same manner as in the above embodiment, and the obtained AD conversion value ADbat is output to the correction circuit 11.

  The correction circuit 11 uses the known voltage values V1 and V2 of the plurality of known voltages set in the storage device 13 and the AD converted values AD1 and AD2 from the AD converted value ADbat obtained by the AD converter 3. A voltage value Vbat not including a measurement error with respect to the output voltage of B is obtained.

  More specifically, referring to FIG. 5, the correction circuit 11 includes known voltage values (voltage values not including a measurement error) V1 and V2 of the plurality of known voltages set in the storage device 13, and AD conversion values ( From the voltage values including measurement errors (AD1, AD2), the following equation (1) representing the straight line S in FIG. 3 (a line in which the correspondence between the AD conversion value ADbat and the voltage value Vbat not including the measurement error is approximated by a straight line). ) And a voltage value Vbat not including a measurement error with respect to the output voltage of the battery B is obtained from the AD conversion value ADbat obtained by the AD converter 3 using the obtained equation (1).

  According to the voltage measuring apparatus 1B configured as described above, AD conversion is performed by inputting the known voltage values V1 and V2 of a plurality of preset known voltages (for example, two) and the circuits 5 and 7 in advance. Correction for removing measurement errors included in the AD conversion value ADbat of the battery voltage obtained by the AD converter 3 using the AD conversion values AD1 and AD2 of the plurality of known voltages obtained by AD conversion by the converter 3 Therefore, not only the measurement error caused by the AD resolution and the measurement error caused by the error of the reference voltage Vref but also the measurement error caused by the circuit elements D1, D2, R1, R2, R3, R4, and P can be removed. The voltage within the specific voltage range in the output voltage range of the battery B can be measured with higher accuracy.

1 is a schematic configuration diagram of a voltage measuring device according to an embodiment of the present invention. It is the figure which showed the output voltage range of the extraction circuit in the voltage measuring device of embodiment of this invention, and the output voltage range of an amplifier circuit. It is the structure schematic of the voltage measuring device which concerns on a modification. It is a figure explaining the method of setting the AD conversion value of the known voltage in the voltage measuring device which concerns on a modification. It is a figure explaining the method of correction | amendment by the correction circuit of the voltage measuring device which concerns on a modification. It is a block schematic diagram of a voltage measuring device according to a first conventional example. It is a structure schematic diagram of the voltage measuring device which concerns on a 2nd prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Voltage measuring device 3 AD converter 5 Cutting-out circuit 7 Amplifying circuit 9 CPU
DESCRIPTION OF SYMBOLS 11 Correction circuit 13 Memory | storage device ADbat AD conversion value of output voltage of battery AD1, AD2 AD conversion value of known voltage B Battery (power supply)
Vref Reference voltage V1, V2 Voltage value of known voltage Vbat Voltage value not including measurement error of battery output voltage

Claims (2)

A voltage measuring device that measures a voltage within a specific voltage range having a width narrower than a reference voltage range of a reference voltage of an AD converter to be used in an output voltage range of a power source to be measured,
A cut-out circuit that cuts out the specific voltage range from the output voltage range of the power supply and outputs a voltage within the specific voltage range;
An amplifying circuit for amplifying the specific voltage range cut out by the cut-out circuit so as to correspond to a reference voltage range of the reference voltage;
The AD converter for obtaining an AD conversion value of the power supply voltage input to the extraction circuit from the voltage transformed corresponding to amplification of the specific voltage range by the amplifier circuit;
A voltage measuring device comprising:   The voltage values of a plurality of known voltages set in advance and the AD conversion values of the plurality of known voltages that are input in advance through the cut-out circuit and the amplifier circuit and are AD-converted by the AD converter. The voltage measuring apparatus according to claim 1, further comprising a correcting unit that performs correction to remove a measurement error included in the AD conversion value of the power supply voltage obtained by the AD converter.

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