JP2007240299A - Flying capacitor system voltage measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage measuring device capable of improving noise resistance without delay of measuring time. <P>SOLUTION: The flying capacitor system voltage measuring device includes a capacitor 3, a first multiplexer 1, a second multiplexer 2, a voltage measuring means 7, a sample voltage measurement switch 4, a control means 7, voltage detection terminals T1 to T5 connected to both ends of voltage sources V1 to V4, respectively, and a plurality of filters comprising a pair of resistors Rf1, Rf2 connected between the multiplexers and a capacitor Cf connected between connection points of the pair of resistors Rf1, Rf2 and the multiplexers. A resistance value of one resistor Rf1 from among the pair of resistors connected to the first and (N+1)-th voltage detection terminals from among the (N+1) voltage detection terminals is set so as to be smaller than a resistance value of the other resistor Rf2 of the pair of resistors, and the total resistance value of the pair of resistors is set so as to be equal in all of the plurality of filters. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flying capacitor type voltage measuring apparatus.

  As a device for measuring the voltage of each individual battery (voltage source) in a high-voltage power source configured by connecting a large number of batteries (voltage sources) in series like a power source of an electric vehicle, a flying capacitor type voltage measuring device There is.

  FIG. 3 is a configuration diagram of a conventional flying capacitor type voltage measuring apparatus. In FIG. 3, voltage sources (for example, batteries) V1 to V4 connected in series in the high-voltage power supply V are connected to a first multiplexer 1 and voltage samples including voltage sample switches S1, S3, and S5 from voltage detection terminals T1 to T5. The capacitor 3 is connected to the voltage measuring circuit 5 via the sample voltage measuring switch 4 consisting of the switches 4a and 4b. The capacitor 3 is connected to the capacitor 3 via the second multiplexer 2 consisting of the switches S2 and S4. Yes.

  A resistor Rf is connected between the voltage detection terminals T1 to T5 and the voltage sample switches S1 to S5 of the first and second multiplexers 1 and 2, and the resistor Rf and the voltage sample switches S1 to S5. A capacitor Cf is connected between the connection points. The resistor Rf and the capacitor Cf constitute a filter circuit 8 that acts as a low-pass filter, reduces noise on the charging path to the capacitor 3, and affects the measurement system after the first and second multiplexers 1 and 2. It is preventing.

  In the above-described configuration, the voltage measuring apparatus selects the desired voltage source by the first and second multiplexers 1 and 2 with the sample voltage measurement switch 4 opened, and then the first and second multiplexers 1 and 2. By repeating the operation of opening 2 and closing the sample voltage measuring switch 4, each voltage of the voltage sources V1 to V4 can be measured in an insulating manner.

  For example, when the voltage sample switches S1 and S2 are closed, the voltage of the voltage source V1 is charged in the capacitor 3. Next, after the voltage sample switches S1 and S2 are opened and then the sample voltage measurement switch 4 is closed, the voltage measurement circuit 5 A voltage corresponding to the charging voltage of the capacitor 3, that is, the voltage of the voltage source V1 is input to the input. In this way, since the multiplexers 1 and 2 and the sample voltage measurement switch 4 are not closed at the same time, the voltage measurement circuit 5 can measure the voltage while being insulated from the voltage source V1.

Further, in this voltage measuring device, the detected voltage of the even-numbered voltage source with respect to the odd-numbered voltage source is inverted in polarity and input to the voltage measuring circuit 5, so that the odd-numbered voltage source and the even-numbered voltage source are input. Polarity correction means 6 for aligning the detection voltage polarity of the source is provided (see, for example, Patent Documents 1 and 2).
Japanese Patent Laid-Open No. 11-248755 JP 2003-114243 A

  However, in the voltage measuring device having the above-described configuration, the resistance Rf and the capacitor Cf of the filter circuit 8 affect the detection accuracy of the measurement voltage (the voltage charged in the capacitor 3). That is, the capacitor 3 is not directly charged with the voltages of the individual voltage sources V1 to V4, but once charged to the capacitor Cf of the filter circuit 8, the charge charged in the capacitor Cf is transferred to the capacitor 3 side. The capacitor 3 is charged by being discharged. Therefore, in order to eliminate the influence of the filter circuit 8, there is a problem that it is necessary to lengthen the measurement time.

  That is, the charging of the capacitor Cf from each of the voltage sources V1 to V4 is limited by the time constant τ = 2Rf * Cf determined by the resistance value of the two resistors Rf and the capacitance of the capacitor Cf. As shown, it takes time to fully charge the capacitor Cf. For example, when voltage sample switches S1 and S2 are closed at time t1 when measuring voltage source V1, the charge of capacitor Cf charged with the voltage of voltage source V1 is discharged to capacitor 3 and capacitor 3 is charged. The voltage across the capacitor Cf is charged so that it once drops slightly from the voltage V1 and then increases with the time constant τ. Next, the switches S1 and S2 are opened at time t2 and the sample voltage measurement switch 4 is closed, whereby the voltage across the capacitor 3 is measured by the voltage measurement circuit 5.

  At this time, in order to remove noise, the resistance value of the resistor Rf of the filter circuit 8 is set to, for example, the order of 10 kΩ to remove noise of several tens to several hundreds of Hz (as a specific example, the capacitance value of the capacitor Cf is 4.7 μF, and the resistance value of the resistor Rf is set to 10 kΩ), the time required to fully charge the capacitor Cf takes many times as long as the time constant τ.

  Therefore, the period P2 from the time t2 to the time t3 when the capacitor Cf is fully charged (saturated) with respect to the period P1 from the time t1 to the time t2 requires many times as long as the period P1. The time required for measurement becomes longer. If the next measurement is started before the capacitor Cf completely returns to the saturated state, accurate voltage measurement cannot be performed.

  If the resistance value of the resistor Rf is reduced so that the capacitance value of the capacitor Cf is sufficiently larger than the capacitance value of the capacitor 3, the above problem is reduced, but the filter constant (cutoff frequency) is changed. If not, if the capacitance value of the capacitor Cf is increased, the shape of the capacitor Cf increases and the component shape increases.

  Further, when measuring the middle voltage source (that is, V2 and V3) of the high-voltage power supply V, the capacitor Cf connected between the voltage detection terminals (that is, between T2 and T3 and between T3 and T4) is the capacitor 3 When charging from the voltage source (i.e., V2 or V3) after discharging, a sneak current from the two upper and lower voltage sources (i.e., voltage sources V1 and V3 or voltage sources V2 and V4) flows. The charging current increases and the battery is charged in a short time.

  For example, when the voltage source V2 is measured, the voltage across the capacitor Cf connected between the voltage detection terminals T2 and T3 becomes lower than the voltage V2 after discharging to the capacitor 3, so that the voltage is detected by this lower amount. The voltage across the capacitor Cf connected between the terminals T1-T2 and between T3-T4 becomes higher than the voltages V3 and V4, respectively. Accordingly, when the capacitor Cf connected between the voltage detection terminals T2 and T3 is charged again after discharging, the capacitor Cf is charged from the voltage source V2 via the resistor Rf, and between the voltage detection terminals T1 and T2 and Charge is also transferred from the capacitor Cf connected between T3 and T4.

  On the other hand, when measuring the voltage sources at both ends of the high-voltage power supply V (that is, V1 and V4), the capacitor Cf connected between the voltage detection terminals (that is, between T1 and T2 and between T4 and T5) is connected to the capacitor 3. Since charging current from only one voltage source (ie, voltage source V2 or voltage source V3) flows from only one side when charging from the voltage source (ie, V1 or V4) after discharging of Is smaller than the charging current at the time of measurement of the middle voltage source (that is, V2 and V3) of the high-voltage power supply V described above.

  For example, when the voltage source V1 is measured, the voltage across the capacitor Cf connected between the voltage detection terminals T1 and T2 becomes lower than the voltage V1 after discharging to the capacitor 3, so that the voltage detection is performed by this lower amount. The voltage across the capacitor Cf connected between the terminals T2 and T3 becomes higher than the voltage V2. Thereby, when the capacitor Cf connected between the voltage detection terminals T1 and T2 is charged again after discharging, the capacitor Cf is charged between the voltage detection terminals T2 and T3 in addition to being charged from the voltage source V1 via the resistor Rf. Charge is also transferred from the connected capacitor Cf for charging.

  Therefore, the charging time of the capacitor Cf when measuring the voltage sources (that is, V1 and V4) at both ends of the high-voltage power supply V is equal to the capacitor Cf when measuring the middle voltage source (that is, V2 and V3) of the high-voltage power supply V. Will be slower than the charging time.

  As a result, the measurement cycle is short (when the next voltage measurement is started after the capacitor Cf is discharged by voltage measurement and before the capacitor Cf is fully charged, and the measurement cycle includes the voltage sources V1, V2, V3 and V4. When it is repeated in the same order, the measurement of the voltage sources (that is, V1 and V4) at both ends of the high-voltage power supply V is compared with the measurement of the middle voltage source (that is, V2 and V3) of the high-voltage power supply V described above. However, there is a problem that the detection accuracy is lowered.

  Furthermore, when the measurement cycle is repeated in the same order of the voltage sources V1, V2, V3, and V4, after measuring the voltage of the voltage source V1, before the capacitor Cf for the voltage source V1 returns to the fully charged state, the voltage source V2 Is started, the voltage across the capacitor Cf for the voltage source V2 is increased by a value that compensates for the fact that the full charge of the capacitor Cf for the voltage source V1 cannot be fully restored. Is measured by the voltage measuring circuit 5, the measured value of the voltage source V2 is measured higher than the true value. Next, when the measurement of the voltage source V3 is started after the voltage measurement of the voltage source V2 and before the capacitor Cf for the voltage source V2 returns to the fully charged state, the voltage across the capacitor Cf for the voltage source V3 is When the voltage across the capacitor 3 is measured by the voltage measuring circuit 5 in this state, the measured value of the voltage source V3 is less than the true value. Will be measured lower. Next, when the measurement of the voltage source V4 is started after the voltage measurement of the voltage source V3 and before the capacitor Cf for the voltage source V3 returns to the fully charged state, the voltage source V4 is measured in the same manner as in the measurement of the voltage source V2. The measured value of V4 is measured higher than the true value.

  As described above, when the measurement cycle is repeated in the same order of the voltage sources V1, V2, V3, and V4, there is a problem that the measurement value is alternately lower than the true value and shifted higher depending on the measurement order. is there.

  Furthermore, when a disconnection occurs in the connection line from the voltage source to the filter circuit, there is a problem that electric charges appear in the capacitor 3 even when the disconnection occurs due to the influence of the capacitor Cf, and it cannot be determined as a failure. For example, even if one of the connection lines of the voltage detection terminal and the resistor Rf is disconnected, the capacitor Cf to be measured is charged due to the wraparound from the other line, so that not only the disconnection cannot be detected but also when the disconnection occurs Is not the voltage of the voltage source to be measured, but the charge charged in the capacitor Cf, that is, a false voltage that is not the voltage source voltage is measured.

  Therefore, in view of the above-described conventional problems, an object of the present invention is to provide a voltage measuring device that can improve noise resistance without delaying measurement time.

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that among the (N + 1) voltage detection terminals connected to a capacitor and N (N is an even number) voltage sources connected in series. A first multiplexer that selectively connects the odd-numbered voltage detection terminals to the capacitor, and a first multiplexer that selectively connects the even-numbered voltage detection terminals of the (N + 1) voltage detection terminals to the capacitor. Two multiplexers, voltage measuring means, a sample voltage measuring switch for supplying a voltage across the capacitor to the voltage measuring means, and control means for controlling the operations of the first and second multiplexers and the sample voltage measuring switch. A pair of resistors connected between the voltage detection terminals connected to both ends of each voltage source and the multiplexer, the resistors and the resistors. A flying capacitor type voltage measuring apparatus including a plurality of filters including capacitors connected between connection points of a chipplexer, wherein the first and (N + 1) th voltages of the (N + 1) voltage detection terminals The resistance value of one of the pair of resistors connected to the detection terminal is set to be smaller than the resistance value of the other resistor of the pair of resistors, and the total resistance value of the pair of resistors is set to the The present invention resides in a flying capacitor type voltage measuring apparatus characterized in that all of a plurality of filters are set equal.

  According to the first aspect of the present invention, an odd-numbered voltage detection terminal among (N + 1) voltage detection terminals connected to a capacitor and N (where N is an even number) voltage source connected in series is provided. A first multiplexer selectively connected to the capacitor; a second multiplexer selectively connecting an even-numbered voltage detection terminal of the (N + 1) voltage detection terminals to the capacitor; a voltage measuring means; a capacitor A sample voltage measurement switch for supplying a voltage measurement means to the voltage measurement means, a control means for controlling the operations of the first and second multiplexers and the sample voltage measurement switch, and a voltage detection terminal connected to both ends of each voltage source. And a pair of resistors connected between the multiplexers and a capacitor connected between the connection points of the resistors and the multiplexers. A flying capacitor type voltage measuring device including a filter, wherein one of a pair of resistors connected to the first and (N + 1) th voltage detection terminals of (N + 1) voltage detection terminals Is set to be smaller than the resistance value of the other resistance of the pair of resistors, and the total resistance value of the pair of resistors is set to be equal in all of the plurality of filters.

  In order to solve the above-mentioned problem, the invention according to claim 2 is the flying capacitor type voltage measuring device according to claim 1, wherein the control means serially connects the N voltage sources connected in series one by one. The voltage measurement is performed by controlling the operations of the first and second multiplexers and the sample voltage measuring switch so as to measure in order from the first to the Nth connection, and in reverse order from the Nth to the first. The means is configured to measure the first voltage source of each voltage source measured in order from the first to the Nth serial connection of the N voltage sources connected in series one by one under the control of the control means. And calculating the average of the second measured values of each voltage source measured in reverse order from the Nth to the first, and determining the average value of the results as the final measured value of each voltage source. It consists in viewing capacitor method voltage measuring device.

  In the invention according to claim 2, the control means measures the N voltage sources connected in series one by one in order from the first to the Nth serial connection, and then measures in reverse order from the Nth to the first. In this manner, the operations of the first and second multiplexers and the sample voltage measurement switch are controlled. The voltage measuring means is controlled by the control means, and the first measured value of each voltage source measured in order from the first to the Nth serially connected N voltage sources one by one, Then, the second measurement value of each voltage source measured in reverse order from the Nth to the first is calculated, and the average value of the result is determined as the final measurement value of each voltage source.

  In order to solve the above-mentioned problems, a third aspect of the present invention is the flying capacitor type voltage measuring device according to the first or second aspect, wherein the odd-numbered voltage detection terminal and the connection point of the resistor Rf1 are connected to the even-numbered number. The first short-circuit resistor Ra connected between the voltage detection terminal and the connection point of the resistor Rf2, and the even-numbered voltage detection terminal and the resistor Rf2 that are not connected to the first short-circuit resistor Ra A second short-circuit resistor Rb having a resistance value greater than that of the first short-circuit resistor Ra, and a terminal of the voltage source adjacent to the odd-numbered voltage detection terminal and the connection point of the resistor Rf1. A flying capacitor system power supply, further comprising: a determination means for determining a disconnection failure when the difference between the measured values is equal to or greater than a preset disconnection determination threshold value. It resides in the measurement device.

  According to a third aspect of the present invention, the flying capacitor type voltage measuring device is connected between the connection point of the odd-numbered voltage detection terminal and the resistor Rf1 and the connection point of the even-numbered voltage detection terminal and the resistor Rf2. Are connected between the connection point of the even-numbered voltage detection terminal and the resistor Rf2, and the connection point of the odd-numbered voltage detection terminal and the resistor Rf1, to which the first short-circuit resistance Ra is not connected. Determination that a disconnection failure is determined when the difference between the second short-circuit resistance Rb having a resistance value greater than one short-circuit resistance Ra and the final measured value of the adjacent voltage source is equal to or greater than a preset disconnection determination threshold value. And means.

  According to the first aspect of the present invention, an odd-numbered voltage detection terminal among (N + 1) voltage detection terminals connected to a capacitor and N (where N is an even number) voltage sources connected in series. A first multiplexer that selectively connects the capacitor to the capacitor, a second multiplexer that selectively connects the even-numbered voltage detection terminal of the (N + 1) voltage detection terminals to the capacitor, voltage measurement means, Sample voltage measurement switch for supplying voltage across the capacitor to the voltage measurement means, control means for controlling the operation of the first and second multiplexers and the sample voltage measurement switch, and voltage detection connected to both ends of each voltage source A plurality of resistors comprising a pair of resistors connected between the terminal and the multiplexer and a capacitor connected between the connection points of the resistors and the multiplexer. And a resistance of one of a pair of resistors connected to the first and (N + 1) th voltage detection terminals of the (N + 1) voltage detection terminals. Is set to be smaller than the other resistance value of the pair of resistors, and the total resistance value of the pair of resistors is set to be equal in all of the plurality of filters, without waiting for the capacitor to be fully charged. Therefore, it is possible to measure an accurate voltage source with good noise resistance without delaying the measurement time. Also, measurement with almost the same detection accuracy is possible when measuring the voltage source at both ends of the high-voltage power supply V and when measuring the voltage source in the middle of the high-voltage power supply V.

  According to a second aspect of the present invention, the control means measures the N voltage sources connected in series one by one in order from the first to the Nth in the series connection, and then in reverse order from the Nth to the first. The voltage measurement means controls the operation of the first and second multiplexers and the sample voltage measurement switch so that the N voltage sources connected in series are connected in series one by one under the control of the control means. The first measurement value of each voltage source measured in order from the first to the Nth and the second measurement value of each voltage source measured in the reverse order from the Nth to the first are calculated. Since the average value of the results is determined as the final measurement value of each voltage source, accurate voltage measurement is possible.

  According to the third aspect of the present invention, the first short-circuit resistor Ra connected between the connection point of the odd-numbered voltage detection terminal and the resistor Rf1 and the connection point of the even-numbered voltage detection terminal and the resistor Rf2, and 1 is connected between the connection point of the even-numbered voltage detection terminal and the resistor Rf2 and the connection point of the odd-numbered voltage detection terminal and the resistor Rf1, and is larger than the first short-circuit resistance Ra. Since there is further provided a second short-circuit resistance Rb having a value and a determination means for determining a disconnection failure when the difference between the final measured values of adjacent voltage sources is equal to or greater than a preset disconnection determination threshold value. Even if there is a filter for improving noise resistance, disconnection can be detected.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  (First Embodiment) FIG. 1 is a circuit diagram showing a configuration of a voltage measuring apparatus according to a first embodiment of the present invention. In FIG. 1, the voltage measuring device is configured as a flying capacitor type voltage measuring device, and includes a first multiplexer 1 and a second multiplexer 2 connected to voltage detection terminals T1 to T5 of a high-voltage power supply V, and a bipolar capacitor 3. , A sample voltage measuring switch 4, a microcomputer (hereinafter referred to as a microcomputer) 7 as a voltage measuring means, and a filter circuit 8.

  High-voltage power supply V includes N voltage sources (for example, batteries) V1 to V4 connected in series (where N is an even number, for example, N = 4 in this embodiment). Each of the voltage sources V1 to V4 has the same voltage and is connected to (N + 1) (in this embodiment, for example, 5) voltage detection terminals T1 to T5.

  The filter circuit 8 includes an odd-numbered voltage detection terminal, that is, a resistor Rf1 connected between T1, T3, T5 and the voltage sample switches S1, S3, S5 of the first multiplexer 1, and an even-numbered voltage detection terminal. That is, the resistor Rf2 connected between T2 and T4 and the voltage sample switches S2 and S4 of the second multiplexer 2, the connection point of the resistor Rf1 and the first multiplexer 1, the resistor Rf2 and the second multiplexer 2, respectively. It is comprised from the some filter which consists of the capacitor | condenser Cf each connected between these connection points. The resistors Rf1 and Rf2 and the capacitor Cf of each filter perform the action of a low-pass filter, remove the noise on the charging line, and eliminate the influence on the measurement system after the first and second multiplexers 1 and 2.

  The resistance values of the resistors Rf1 and Rf2 are set to have a relationship of Rf1 + Rf2 = 2Rf and Rf1 << Rf2. For example, Rf = 10 kΩ, Rf1 = 1 kΩ, and Rf2 = 19 kΩ are set. At this time, the capacitor 3 is set to 0.1 μF, and the capacitor Cf is set to 4.7 μF. As the capacitor 3 and the capacitor Cf, chip-shaped ceramic capacitors having the same characteristics (the same series and the same breakdown voltage) are used.

  The voltage sample switches S1, S3, S5 of the first multiplexer 1 are connected to one terminal of the capacitor 3, and the voltage sample switches S2, S4 of the second multiplexer 2 are connected to the other terminal of the capacitor 3. Yes.

  The sample voltage measurement switch 4 includes a switch 4 a connected to one terminal of the capacitor 3 and a switch 4 b connected to the other terminal of the capacitor 3.

  The microcomputer 7 includes a power supply port Vcc to which a drive voltage from a power supply + Vcc is supplied, and input ports A / D1 and A / D2 connected to the switches 4a and 4b of the sample voltage measurement switch 4, respectively. The microcomputer 7 functions as voltage measuring means, control means, and determination means in the claims.

  Next, the operation (measurement procedure) of the flying capacitor type voltage measuring apparatus having the above-described configuration will be described. First, when the voltage sample switches S1 to S5 of the multiplexers 1 and 2 and the switches 4a and 4b of the sample voltage measuring switch 4 are all open, the voltages of the voltage sources V1 to V4 are applied to the capacitors Cf of the filter circuit 8, respectively. It is charged.

  From this state, when the voltage sample switch S1 of the first multiplexer 1 and the voltage sample switch S2 of the second multiplexer 2 are closed by the open / close control of the microcomputer 7, the capacitor Cf, the voltage sample switch S1, the capacitor 3, and the voltage sample switch A closed circuit is formed by S2. As a result, the capacitor 3 is connected in parallel to the capacitor Cf, the charge accumulated in the capacitor Cf is discharged to the capacitor 3, and the terminal side of the capacitor 3 connected to the voltage sample switch S1 has a positive polarity. Thus, the capacitor 3 is charged.

  Next, the voltage sample switches S1 and S2 are opened, the switches 4a and 4b of the sample voltage measuring switch 4 are closed for a predetermined period, and the voltage across the capacitor 3 is connected to the first and second of the microcomputer 7 via the switches 4a and 4b. To the input ports A / D1 and A / D2.

  The microcomputer 7 performs A / D (analog / digital) conversion on the voltage across the capacitor 3 applied to the first and second input ports A / D1 and A / D2 and reads it as a digital value. The microcomputer 7 calculates the voltage of the voltage source V1 by calculating (read value) × (Cf + C1) / Cf, assuming that the capacitance values of the capacitor Cf and the capacitor 3 are Cf and C1, respectively. The calculated value is stored in the internal memory of the microcomputer 7 as the first measurement value.

  Next, when the voltage sample switches S2 and S3 are closed, a closed circuit is formed by the capacitor Cf, the voltage sample switch S2, the capacitor 3, and the voltage sample switch S3. As a result, similarly, the capacitor 3 is connected in parallel to the capacitor Cf, the charge accumulated in the capacitor Cf is discharged to the capacitor 3, and the terminal side of the capacitor 3 connected to the voltage sample switch S2 is positive. The capacitor 3 is charged with a polarity opposite to that at the time of measurement of the voltage source V1 so as to be polar.

  Next, the voltage sample switches S2 and S3 are opened, the switches 4a and 4b of the sample voltage measurement switch 4 are closed for a predetermined period, and the voltage across the capacitor 3, that is, the voltage of the voltage source V2 is passed through the sample voltage measurement switch 4. The first and second input ports A / D1 and A / D2 of the microcomputer 7 are supplied.

  The microcomputer 7 performs A / D (analog / digital) conversion on the voltage across the capacitor 3 applied to the first and second input ports A / D1 and A / D2 and reads it as a digital value. The microcomputer 7 calculates the voltage of the voltage source V2 by calculating (read value) × (Cf + C1) / Cf, assuming that the capacitance values of the capacitor Cf and the capacitor 3 are Cf and C1, respectively. The calculated value is stored in the internal memory of the microcomputer 7 as the first measurement value.

  Similarly, the microcomputer 7 measures the values indicating the voltages of the voltage sources V3 and V4 by the combination of the voltage sample switches S3 and S4, S4 and S5, respectively.

  Next, after measuring these voltages in the order of the voltage sources V1, V2, V3, and V4 and calculating these voltages, the same measurement is performed by replacing the order with the voltage sources V4, V3, V2, and V1. Is calculated. The calculated value at this time is stored in the internal memory of the microcomputer 7 as the second measured value.

  Next, the microcomputer 7 performs an operation of averaging the first calculated value and the second calculated value of the voltage source V1 measured twice, and determines the average value as the operation result as the final calculated value of the voltage source V1. . Similarly, the average value obtained by averaging the calculated values of the voltage sources V2 to V4 measured twice is determined as the final calculated value of the voltage sources V2 to V4. These determined final calculated values are stored in the internal memory of the microcomputer 7.

  As described above, in the voltage measuring apparatus of FIG. 1, the charge of the capacitor 3 is not regarded as the voltage of the individual voltage source, but the voltage of the individual voltage source charged in the capacitor Cf is treated as being converted into the capacitance of Cf + C1. Thus, it is possible to accurately measure the voltage source without waiting for the capacitor 3 to be fully charged.

  In the above measurement operation, when measuring the voltage source V1 (or V4) at both ends of the high-voltage power supply V, the capacitor Cf is charged from the voltage source V1 (or V4) when charged after discharging to the capacitor 3. In addition to this, the sneak current from only one voltage source V2 (or V3) flows from one side is the same as in the conventional example of FIG. 2, but the resistance values of the resistors Rf1 and RF2 of the filter circuit 8 are Rf1 + Rf2 = 2Rf And Rf1 << Rf2, the charging current flowing from the voltage source V1 or V4 through the resistor Rf1 is larger than that in the conventional example of FIG. Almost the same charging current can be ensured as when measuring the sources (ie, V2 and V3). As a result, when measuring the voltage source (that is, V1 and V4) at both ends of the high-voltage power supply V and measuring the voltage source in the middle of the high-voltage power supply V (that is, V2 and V3), the measurement with almost the same detection accuracy. Is possible.

  Further, since the time constant of the filter circuit 8 has the same value as that of the conventional example of FIG. 2, the operation of the low-pass filter is not different from that of the conventional example of FIG. A decrease in detection accuracy can be prevented.

  Furthermore, the measurement order of the voltage source is set to V1 → V2 → V3 → V4 → V4 → V3 → V2 → V1, and the average value of the two measurements is set as the final calculated value. Measured value V1 (measured value is lower than true value) → V2 (measured value is higher than true value) → V3 (measured value is lower than true value) → V4 (measured value is true value) → V4 (measurement value is lower than true value) → V3 (measurement value is higher than true value) → V2 (measurement value is lower than true value) → V1 (measurement value is true) The higher and lower deviations are canceled out, and accurate voltage measurement becomes possible.

  In addition, the capacitor 3 and the capacitor Cf use chip-shaped ceramic capacitors having the same characteristics (the same series and the same breakdown voltage), which helps to reduce the size of the device. In general, a ceramic capacitor has a DC bias characteristic in which a capacitance value varies depending on a DC applied voltage. However, by using the same characteristic product (the same series product, the same breakdown voltage product) for the capacitor 3 and the capacitor Cf, the above-mentioned ( It is possible to cancel the capacity fluctuation at the time of calculation of (read value) × (Cf + C1) / Cf. If a product with the same characteristics cannot be prepared, the DC bias characteristics of the ceramic capacitor used for the capacitor 3 and the DC bias characteristics of the ceramic capacitor used for the capacitor Cf are grasped in advance, and the capacitance variation that cannot be canceled is obtained. It can be corrected in software.

  (Second Embodiment) FIG. 2 is a circuit diagram showing a configuration of a voltage measuring apparatus according to a second embodiment of the present invention. In addition to the configuration shown in FIG. 1, the voltage measuring device shown in FIG. 2 has a voltage between the voltage detection terminals T1 and T2 in order to detect this disconnection when a disconnection occurs in the connection line from the voltage source to the filter circuit. A resistor Ra is connected between the detection terminals T3 and T4, and a resistor Rb is connected between the voltage detection terminals T2 and T3 and between the voltage detection terminals T4 and T5. The resistor Ra and the resistor Rb are resistors having different resistance values. For example, in this embodiment, the resistor Ra is selected to be 1 MΩ and the resistor Rb is selected to be 2 MΩ.

In the above configuration, when normal in actual use, when measuring adjacent voltage sources, and when the potential difference (difference) of the final measured value is smaller than the disconnection determination threshold, disconnection is detected by the following determination method. be able to.
(1) Connection lines at both ends (positive line of the voltage source V1 from the voltage source V1 to the resistor Ra through the voltage detection terminal T1 and connection from the voltage source V4 to the resistor Rb through the voltage detection terminal T5 When the voltage of the voltage source V1 or V4 is measured and the measured value is 0V, the microcomputer 7 determines that the circuit is disconnected.
(2) When the center connection line (connection line other than the connection line of (1) above) is disconnected (for example, when the portion marked with X in FIG. 2 is disconnected)
When disconnection occurs, the voltage across the two capacitors Cf connected between the voltage detection terminals T1 and T2 and between T2 and T3 is the sum of the voltage source V1 and the voltage source V2. Since the two capacitors Cf are sneak from all the resistors Ra and Rb, the resistor Ra connected between the voltage detection terminals T1 and T2 and the resistor connected between the voltage detection terminals T2 and T3. The voltage obtained by dividing the voltage at the disconnection portion by all the resistors Ra and Rb appears as the difference between the voltages at both ends of the two capacitors Cf at the disconnection portion, not the voltage division ratio of Rb. That is, the final measurement value of the voltage source adjacent to the disconnection portion, for example, the final measurement value of the voltage sources V1 and V2,
| Final measurement value of voltage source V1−Final measurement value of voltage source V2 | / Final measurement value of voltage source V1 + Final measurement value of voltage source V2 = | Ra / total of each resistance−Rb / total of each resistance |
(For example, in the case of resistors Ra = 1 MΩ, Rb = 2 MΩ, and V1 to V4, the voltage difference between V1 and V2 is 1/6 of V1 + V2), and disconnection is detected. When a disconnection judgment threshold value that satisfies this condition at the minimum voltage is preset and stored in the internal memory of the microcomputer 7, and the microcomputer 7 detects a potential difference (difference) that is greater than this disconnection judgment threshold value It is possible to detect disconnection by determining the disconnection.

  As an example, if the positive side line of the voltage source V2 connected to the filter circuit 8 via the voltage detection terminal T2 is disconnected, the V1 to V4 minimum voltage for detecting the disconnection is predetermined as 7.5V. Since V1 + V2 = 15V and the total sum of resistances = 6MΩ, | V1-V2 | / V1 + V2 = 1/6 is V1-V2 (voltage measurement value of voltage source V1−voltage measurement value of voltage source V2) Is 2.5V, so that the potential difference between adjacent channels is 2.5V or more (if the voltage difference between channels does not become larger than 2.5V when normal in actual use) If it is determined that a disconnection occurs when the threshold value is equal to or higher than the threshold value, the disconnection can be detected when V1 to V4 are 7.5 V or higher.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, A various deformation | transformation and application are possible.

It is a circuit diagram which shows the structure of the voltage measuring device which concerns on the 1st Embodiment of this invention. (First embodiment) It is a circuit diagram which shows the structure of the voltage measuring device which concerns on the 2nd Embodiment of this invention. (Second Embodiment) It is a block diagram of the conventional flying capacitor system voltage measuring device. It is a figure for demonstrating operation | movement of the measuring apparatus of FIG.

Explanation of symbols

S1 to S6, 4a, 4b switch Rf resistance Rf1 resistance Rf2 resistance Ra resistance (first short-circuit resistance)
Rb resistance (second short-circuit resistance)
T1 to T5 Voltage detection terminals V1 to V5 Voltage source 1 First multiplexer 2 Second multiplexer 3 Capacitor 4 Sample voltage measurement switch 7 Microcomputer (voltage measurement means, control means, determination means)

Claims (3)

A capacitor and an odd-numbered voltage detection terminal among (N + 1) voltage detection terminals connected to N (where N is an even number) voltage source connected in series are selectively connected to the capacitor. 1 multiplexer, a second multiplexer that selectively connects an even-numbered voltage detection terminal of the (N + 1) voltage detection terminals to the capacitor, voltage measuring means, and voltage across the capacitor. A sample voltage measurement switch to be supplied to the measurement means, a control means for controlling the operations of the first and second multiplexers and the sample voltage measurement switch, a voltage detection terminal connected to both ends of each voltage source, and the A compound consisting of a pair of resistors connected between multiplexers and a capacitor connected between the resistors and the connection point of the multiplexers. A flying capacitor method voltage measuring device and a filter,
The resistance value of one of the pair of resistors connected to the first and (N + 1) th voltage detection terminals of the (N + 1) voltage detection terminals is set as the other of the pair of resistors. And a total resistance value of the pair of resistors is set to be equal for all of the plurality of filters. In the flying capacitor type voltage measuring device according to claim 1,
The control means is configured to measure the N voltage sources connected in series one by one in order from the first to the Nth in series, and then measure in reverse order from the Nth to the first. And control the operation of the second multiplexer and the sample voltage measurement switch;
The voltage measurement means is a first measurement value of each voltage source obtained by measuring the N voltage sources connected in series one by one in order from the first to the Nth serial connection under the control of the control means. Then, an arithmetic operation is performed to average the measured values of the second voltage sources measured in reverse order from the Nth to the first, and the average value of the results is determined as the final measured value of each voltage source. Flying capacitor type voltage measuring device. In the flying capacitor type voltage measuring device according to claim 1 or 2,
A first short-circuit resistor connected between the connection point of the odd-numbered voltage detection terminal and the resistor and the connection point of the even-numbered voltage detection terminal and the resistor;
The first short-circuit resistor is connected between the even-numbered voltage detection terminal and the connection point of the resistor and the odd-numbered voltage detection terminal and the connection point of the resistor, to which the first short-circuit resistance is not connected. A second short circuit resistor having a greater resistance value;
A flying capacitor type voltage measuring apparatus, further comprising: a determination unit that determines a disconnection failure when a difference between final measurement values of adjacent voltage sources is equal to or greater than a preset disconnection determination threshold value.

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