JP5368283B2 - Voltage detection circuit - Google Patents

Description

  The present invention relates to a voltage detection circuit, and more particularly to a voltage detection circuit using a flying capacitor.

  As a power source of a motor and a drive source of a load in an electric vehicle such as a hybrid vehicle or an electric vehicle, an assembled battery including a nickel hydrogen battery or a lithium ion battery is used.

  An assembled battery mounted on an electric vehicle is configured by connecting a plurality of blocks in series, and each block is configured by further connecting a single or a plurality of battery cells in series. In order to control the state of the assembled battery or to detect an abnormality in the assembled battery, a management device is provided for each block to detect the voltage of the block.

  FIG. 3 shows an example of a conventional voltage detection circuit. One block B constituting the assembled battery is composed of a single or a plurality of battery cells. In the figure, three blocks B1, B2, and B3 are shown as an example of the block. Blocks B1 to B3 are connected in series with each other.

  The switch S1 is provided on the positive side of the block B1, and the switch S2 is provided on the negative side of the block B1 and the positive side of the block B2. A switch S3 is provided on the negative side of the block B2 and the positive side of the block B3. A switch S4 is provided on the negative side of the block B3.

  The switches S1 and S3 are connected to the signal line L1, and the switches S2 and S4 are connected to the signal line L2.

  When detecting the voltage of the block B1, the switch S1 and the switch S2 are turned on, and the other switches are turned off. By turning on the switches S1 and S2, the positive side of the block B1 is connected to the signal line L1, and the negative side of the block B1 is connected to the signal line L2. When detecting the voltage of the block B2, the switches S2 and S3 are turned on, and the other switches are turned off. By turning on the switches S2 and S3, the positive side of the block B2 is connected to the signal line L2, and the negative side of the block B2 is connected to the signal line L1. When detecting the voltage of the block B3, the switch S3 and the switch S4 are turned on, and the other switches are turned off. By turning on the switches S3 and S4, the positive side of the block B3 is connected to the signal line L1, and the negative side of the block B3 is connected to the signal line L2.

  The signal line L1 is connected to one input terminal of the voltage measuring unit 14 via the switch S5 and the resistor R1. The signal line L2 is connected to the other input terminal of the voltage measuring unit 14 via the switch S7 and the resistor R3.

  Flying capacitors C1 and C2 are connected in series between the signal line L1 and the signal line L2. The two flying capacitors C1 and C2 have the same capacity. A reference power source is connected to a connection point P between the two flying capacitors C1 and C2 via a switch S6 and a resistor R2.

  The input protection circuits 10 and 12 are connected to a connection point R between the resistor R1 and the voltage measurement unit 14 in the signal line L1 and a connection point S between the resistance R3 and the voltage measurement unit 14 in the signal line L2, respectively. Is done. The input protection circuits 10 and 12 are composed of two diodes connected in antiparallel with each other, one of the diodes being connected to a specific power source and the other being grounded.

  In such a circuit configuration, when detecting the voltage of the block B1, the switches S5, S6 and S7 are turned off, the switches S1 and S2 are turned on, and the flying capacitors C1 and C2 are charged with the voltage of the block B1. The voltage of B1 is sampled and held in the flying capacitors C1 and C2.

  Next, the switches S1 and S2 are turned OFF, the switch S6 is turned ON, and the reference voltage is set by the resistor R2 and the reference power supply. Then, the switches S5 and S7 are turned ON and the stored voltage of the flying capacitors C1 and C2 is set to the signal line. The voltage is supplied to L1 and L2, and the voltage measurement circuit 14 detects the voltage.

  FIG. 4 shows another circuit configuration of the conventional voltage detection circuit. The connections of the switches S1 to S4, the flying capacitors C1 and C2, the switches S5 and S7, the input protection circuits 10 and 12, and the voltage measuring unit 14 are the same as in FIG. 3, but the next stage of the flying capacitors C1 and C2, ie, the block Capacitors C3 and C4 are connected in series to the voltage measuring unit 14 side as viewed from B1 to B3. The capacitor C3 is connected to a connection point between the switch S5 and the resistor R1 of the signal line L1, and the capacitor C4 is connected to a connection point between the switch S7 of the signal line L2 and the resistor R2. A reference voltage is connected to a connection point Q between the capacitors C3 and C4 via a resistor R2. Capacitors C3 and C4 have a smaller capacitance than flying capacitors C1 and C2.

  In such a configuration, when detecting the voltage of the block B1, the switches S5 and S7 are turned OFF, the switches S1 and S2 are turned ON, and the flying capacitors C1 and C2 are charged with the voltage of the block B1, and the voltage of the block B1 is changed. Sample and hold the flying capacitors C1 and C2.

  Next, the switches S1 and S2 are turned off, the switches S5 and S7 are turned on, the stored voltage of the flying capacitors C1 and C2 is distributed to the capacitors C3 and C4, and connected to the reference power source through the resistor R2, and the voltage measuring unit 14 The voltage is detected. Since the switches S5 and S7 are OFF while the switches S1 and S2 are ON, the reference power supply is disconnected from the high-voltage block B1, and the high breakdown voltage switch S6 in FIG. 3 is unnecessary.

  In Patent Document 1 below, a capacitor having a capacitance smaller than that of the flying capacitor is provided in the next stage of the flying capacitor for the purpose of reducing the common mode noise voltage, that is, the difference in potential fluctuation between the signal lines L1 and L2. A configuration for connection is disclosed.

Japanese Patent No. 3791767

  In the configuration of FIG. 4, although the high breakdown voltage switch S6 can be eliminated by providing the capacitors C3 and C4, the number of parts is still large, and the effect of cost reduction and space saving is limited. In addition, since the input protection circuit 10 connected to the signal line L1 and the input protection circuit 12 connected to the signal line L2 exist, the circuit area increases accordingly.

  An object of the present invention is to provide a voltage detection circuit capable of reducing the number of parts and reducing the circuit area as compared with the prior art.

The present invention is a voltage detection circuit, sequentially connecting both ends of a flying capacitor and a plurality of detected voltage sources connected in series with each other , sequentially connected to the flying capacitor according to the voltage of the detected voltage source , a first switch group for charging the flying capacitor at opposite polarities alternately, the voltage measuring unit, a pair of second switches for connecting both ends of the flying capacitor to the voltage measurement unit, the pair first 2 is an overvoltage protection element that is connected between the switch and the voltage measuring unit and distributes the storage voltage of the flying capacitor, and includes a first element and a second element connected in series with each other , the first element being The first and second Zener diodes are connected in opposite directions, and the second elements are connected in opposite directions. It comprises a third Zener diode and a fourth Zener diode, the cathode terminal of the first Zener diode is connected to the voltage measuring unit, and the anode terminal of the first Zener diode and the anode terminal of the second Zener diode are connected to each other. The cathode terminal of the second Zener diode is connected to the cathode terminal of the third Zener diode and is connected to the reference voltage source. The anode terminal of the third Zener diode and the anode terminal of the fourth Zener diode are connected to each other. The cathode terminal of the fourth Zener diode includes an overvoltage protection element connected to the voltage measurement unit .

  The detected voltage source in the present invention can be a battery constituting an assembled battery mounted on a vehicle.

  According to the present invention, it is possible to obtain a voltage detection circuit having a smaller number of parts and a smaller circuit area than conventional ones.

It is a circuit block diagram of an embodiment. It is a circuit block diagram of other embodiment. It is a conventional circuit block diagram. It is another conventional circuit block diagram.

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

FIG. 1 shows a circuit configuration of a voltage detection circuit in the present embodiment. One block B constituting an assembled battery mounted on an electric vehicle such as a hybrid vehicle or an electric vehicle is composed of a single or a plurality of battery cells . In the figure, three blocks B1, B2, and B3 are shown as an example of the block. Blocks B1 to B3 are connected in series with each other.

  The switch S1 is provided on the positive side of the block B1, and the switch S2 is provided on the negative side of the block B1 and the positive side of the block B2. A switch S3 is provided on the negative side of the block B2 and the positive side of the block B3. A switch S4 is provided on the negative side of the block B3.

  The switches S1 and S3 are connected to the signal line L1, and the switches S2 and S4 are connected to the signal line L2.

  When detecting the voltage of the block B1, the switch S1 and the switch S2 as a pair of first switches are turned on, and the other switches are turned off. By turning on the switches S1 and S2, the positive side of the block B1 is connected to the signal line L1, and the negative side of the block B1 is connected to the signal line L2. When detecting the voltage of the block B2, the switch S2 and the switch S3 as a pair of first switches are turned on, and the other switches are turned off. By turning on the switches S2 and S3, the positive side of the block B2 is connected to the signal line L2, and the negative side of the block B2 is connected to the signal line L1. When detecting the voltage of the block B3, the switches S3 and S4 are turned on as a pair of first switches, and the other switches are turned off. By turning on the switches S3 and S4, the positive side of the block B3 is connected to the signal line L1, and the negative side of the block B3 is connected to the signal line L2.

  The signal line L1 is connected to one input terminal of the voltage measuring unit 14 via the switch S5 and the resistor R1. The signal line L2 is connected to the other input terminal of the voltage measuring unit 14 via the switch S6 and the resistor R3.

  Flying capacitors C1 and C2 are connected in series between the signal line L1 and the signal line L2. The two flying capacitors C1 and C2 have the same capacity.

  Four Zener diodes ZD1, ZD2, ZD3, and ZD4 are connected between a connection point T between the switch S5 and the resistor R1 of the signal line L1 and a connection point U between the switch S6 and the resistor R3 of the signal line L2. Is done. Zener diodes ZD1 and ZD2 constitute a pair, and Zener diodes ZD3 and ZD4 constitute another pair. Zener diodes ZD1 and ZD2 are connected in series so that their anode terminals are connected to each other and are opposite to each other. That is, the cathode terminal of the Zener diode ZD1 is connected to the connection point T of the signal line L1, and the anode terminal of the Zener diode ZD1 is connected to the anode terminal of the Zener diode ZD2. The cathode terminal of the Zener diode ZD2 is connected to the connection point V. The Zener diodes ZD3 and ZD4 are also connected in series so that their anode terminals are connected to each other and are opposite to each other. That is, the cathode terminal of the Zener diode ZD4 is connected to the connection point U of the signal line L2, and the anode terminal of the Zener diode ZD4 is connected to the anode terminal of the Zener diode ZD3. The cathode terminal of the Zener diode ZD3 is connected to the connection point V. A cathode terminal of the Zener diode ZD2 and a cathode terminal of the Zener diode ZD3 are connected to the connection point V, and a reference power source is connected through the resistor R2. Therefore, the reference voltage is set at the connection point V by the reference power supply.

  Two input terminals of the voltage measuring unit 14 are connected to connection points T and U via resistors R1 and R3, respectively. The circuit configuration of the voltage measurement unit 14 is arbitrary and may be the same as that of the conventional technique. For example, the voltage measuring unit 14 includes a differential amplifier circuit, the non-inverting input terminal of the differential amplifier circuit is connected to the connection point T through the resistor R1, and the inverting input terminal of the differential amplifier is connected through the resistor R3. To connect to the connection point U. The voltage measuring unit 14 may further include an A / D converter, which converts the analog output of the differential amplifier into a digital signal and outputs the digital signal.

  The switches S1 to S6, the flying capacitors C1 and C2, the resistors R1 to R3, the Zener diodes ZD1 to ZD4, and the voltage measuring unit 14 can be unitized as one unit as an ECU (electronic control unit).

  In such a configuration, when detecting the voltage of the block B1, the switches S1 and S2 as a pair of first switches are turned on, and the other switches are turned off. The positive side of the block B1 is connected to the signal line L1, and the negative side of the block B1 is connected to the signal line L2. The flying capacitors C1 and C2 are charged with the voltage of the block B1, and the voltage of the block B1 is set to the flying capacitors C1 and C2. Hold the sample.

  Next, the switches S1 and S2 are turned off, and the switches S5 and S6 as a pair of second switches are turned on. Then, the stored voltage of the flying capacitors C1 and C2 is distributed by the Zener diodes ZD1 to ZD4, connected to the reference power source through the resistor R2, and detected by the voltage measuring unit 14. On the other hand, when the stored voltage of the flying capacitors C1 and C2 is an overvoltage, the overvoltage becomes larger than the rated breakdown voltage of the Zener diodes ZD1 and ZD3 that are reverse biased among the Zener diodes ZD1 to ZD4, that is, the Zener voltage. The zener diodes ZD1 and ZD3 are energized to keep the voltage constant. That is, the Zener diodes ZD1 and ZD3 function as an input protection circuit having a certain capacity.

  Further, when detecting the voltage of the block B2, after discharging the flying capacitors C1 and C2, the switches S2 and S3 as the pair of first switches are turned on, and the other switches are turned off. The positive side of the block B2 is connected to the signal line L2, and the negative side of the block B2 is connected to the signal line L1, and the flying capacitors C1, C2 are charged with the voltage of the block B2, and the voltage of the block B2 is set to the flying capacitors C1, C2. Hold the sample.

  Next, the switches S2 and S3 are turned off, and the switches S5 and S6 as a pair of second switches are turned on. Then, the stored voltage of the flying capacitors C1 and C2 is distributed by the Zener diodes ZD1 to ZD4, connected to the reference power source through the resistor R2, and detected by the voltage measuring unit. On the other hand, when the stored voltage of the flying capacitors C1 and C2 is an overvoltage, the overvoltage becomes larger than the rated breakdown voltage of the Zener diodes ZD2 and ZD4 that are reverse biased among the Zener diodes ZD1 to ZD4, that is, the Zener voltage. The zener diodes ZD2 and ZD4 are energized to keep the voltage constant. That is, the Zener diodes ZD2 and ZD4 function as an input protection circuit having a certain capacity.

  When detecting the voltage of the block B3, after discharging the flying capacitors C1 and C2, the switches S3 and S4 as a pair of first switches are turned on, and the other switches are turned off. The positive side of the block B3 is connected to the signal line L1, the negative side of the block B3 is connected to the signal line L2, the flying capacitors C1 and C2 are charged with the voltage of the block B3, and the voltage of the block B3 is set to the flying capacitors C1 and C2. Hold the sample.

  Next, the switches S3 and S4 are turned off, and the switches S5 and S6 as a pair of second switches are turned on. Then, the stored voltage of the flying capacitors C1 and C2 is distributed by the Zener diodes ZD1 to ZD4, connected to the reference power source through the resistor R2, and detected by the voltage measuring unit. On the other hand, when the stored voltage of the flying capacitors C1 and C2 is an overvoltage, the overvoltage becomes larger than the rated breakdown voltage of the Zener diodes ZD1 and ZD3 that are reverse biased among the Zener diodes ZD1 to ZD4, that is, the Zener voltage. The zener diodes ZD1 and ZD3 are energized to keep the voltage constant. That is, the Zener diodes ZD1 and ZD3 function as an input protection circuit having a certain capacity.

  The voltages of the blocks B1 to B3 detected by the voltage measuring unit 14 are supplied as detection signals to a control device (not shown). Based on the detection signal, the control device calculates normality / abnormality of each of the blocks B1 to B3, normality / abnormality of the assembled battery composed of the blocks B1 to B3, or a state of charge (SOC) of the assembled battery. .

  As described above, in the present embodiment, Zener diodes ZD1 to ZD4 having fixed capacitances are provided instead of the capacitors C3 and C4 in the next stage of the flying capacitors C1 and C2 shown in FIG. 4, and the storage voltages of the flying capacitors C1 and C2 are provided. Are distributed by the Zener diodes ZD1 to ZD4, connected to the reference power supply through the resistor R2, and detected by the voltage measuring unit 14, so that the capacitors C3 and C4 are made unnecessary and the input protection connected to the signal lines L1 and L2 The circuits 10 and 12 are also unnecessary. Thereby, the number of parts can be reduced and the circuit area can be reduced. When the circuit configuration of the present embodiment is compared with FIG. 3, it can be said that the high breakdown voltage switch S6 is unnecessary and the input protection circuits 10 and 12 are unnecessary.

  FIG. 2 shows a circuit configuration of a voltage detection circuit according to another embodiment.

  The switch S1 is provided on the positive side of the block B1, and the switch S2 is provided on the negative side of the block B1 and the positive side of the block B2. A switch S3 is provided on the negative side of the block B2 and the positive side of the block B3. A switch S4 is provided on the negative side of the block B3.

  The switches S1 and S3 are connected to the signal line L1, and the switches S2 and S4 are connected to the signal line L2.

  The signal line L1 is connected to one input terminal of the voltage measuring unit 14 via the switch S5 and the resistor R1. The signal line L2 is connected to the other input terminal of the voltage measuring unit 14 via the switch S6 and the resistor R3.

  Flying capacitors C1 and C2 are connected in series between the signal line L1 and the signal line L2. The two flying capacitors C1 and C2 have the same capacity.

  On the other hand, the varistors VS1 and VS2 are connected in series between the connection point T between the switch S5 and the resistor R1 of the signal line L1 and the connection point U between the switch S6 and the resistor R3 of the signal line L2. . The varistor VS1 and varistor VS2 are connected at a connection point V, and a reference power source is connected to the connection point V via a resistor R2. Therefore, the reference voltage is set at the connection point V by the reference power supply.

  The two input terminals of the voltage measuring unit 14 are connected to connection points T and U via resistors R1 and R3, respectively. The circuit configuration of the voltage measuring unit 14 is the same as that shown in FIG. The voltage measurement unit 14 may include an A / D converter, and may convert the analog output of the differential amplifier into a digital signal and output it.

  Thus, in this embodiment, two varistors VS1 and VS2 are connected to the signal lines L1 and L2 instead of the Zener diodes ZD1 to ZD4. The varistors VS1 and VS2 are non-linear resistance elements. When the voltage between the terminals of the varistors VS1 and VS2 is low, the electric resistance is high, but when the voltage exceeds a certain voltage, the electric resistance rapidly decreases and the conduction current increases. To do. Accordingly, the varistors VS1 and VS2 also function as an input protection circuit having a constant capacity, that is, an overvoltage protection circuit having a constant capacity, similarly to the Zener diode.

  When detecting the voltage of the block B1, the switches S1 and S2 are turned on, and the other switches are turned off. The positive side of the block B1 is connected to the signal line L1, and the negative side of the block B1 is connected to the signal line L2. The flying capacitors C1 and C2 are charged with the voltage of the block B1, and the voltage of the block B1 is set to the flying capacitors C1 and C2. Hold the sample.

  Next, the switches S1 and S2 are turned off, and the switches S5 and S6 are turned on. Then, the stored voltage of the flying capacitors C1 and C2 is distributed by the varistors VS1 and VS2, connected to the reference power source through the resistor R2, and detected by the voltage measuring unit 14. On the other hand, when the stored voltage of the flying capacitors C1 and C2 is an overvoltage, the electrical resistance of the varistors VS1 and VS2 is lowered and maintained at the varistor voltage.

  When the voltage of the block B2 is detected, after the flying capacitors C1 and C2 are discharged, the switches S2 and S3 are turned on and the other switches are turned off. The positive side of the block B2 is connected to the signal line L2, and the negative side of the block B2 is connected to the signal line L1, and the flying capacitors C1, C2 are charged with the voltage of the block B2, and the voltage of the block B2 is set to the flying capacitors C1, C2. Hold the sample.

  Next, the switches S2 and S3 are turned off, and the switches S5 and S6 are turned on. Then, the stored voltage of the flying capacitors C1 and C2 is distributed by the varistors VS1 and VS2, connected to the reference power source through the resistor R2, and detected by the voltage measuring unit. On the other hand, when the stored voltage of the flying capacitors C1 and C2 is an overvoltage, the electrical resistance of the varistors VS1 and VS2 is lowered and maintained at the varistor voltage.

  When detecting the voltage of the block B3, after discharging the flying capacitors C1 and C2, the switches S3 and S4 are turned ON, and the other switches are turned OFF. The positive side of the block B3 is connected to the signal line L1, the negative side of the block B3 is connected to the signal line L2, the flying capacitors C1 and C2 are charged with the voltage of the block B3, and the voltage of the block B3 is set to the flying capacitors C1 and C2. Hold the sample.

  Next, the switches S3 and S4 are turned off, and the switches S5 and S6 are turned on. Then, the stored voltage of the flying capacitors C1 and C2 is distributed by the varistors VS1 and VS2, connected to the reference power source through the resistor R2, and detected by the voltage measuring unit. On the other hand, when the stored voltage of the flying capacitors C1 and C2 is an overvoltage, the electrical resistance of the varistors VS1 and VS2 is lowered and maintained at the varistor voltage.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, A various deformation | transformation is possible. That is, in this embodiment, the example in which the Zener diodes ZD1 to ZD4 are connected between the connection point T in the signal line L1 and the connection point U in the signal line L2 and the example in which the varistors VS1 and VS2 are connected are shown. Other elements can be used as long as they are elements (overvoltage protection elements) having a certain capacity and having a function of energizing and maintaining the applied voltage constant when a voltage higher than a certain voltage is applied.

  Moreover, in this embodiment, although the block of the assembled battery mounted in a vehicle is made into a detected object, it is not limited to this, It can apply to arbitrary voltage sources.

  In this embodiment, the switches S1 to S4 are sequentially turned ON / OFF in order to sequentially detect the terminal voltages of the plurality of blocks B1 to B3. However, only a single block, for example, the block B1 is to be detected. Alternatively, only the switches S1 and S2 may be provided. In this case, only a pair of Zener diodes ZD1 and ZD3 may be connected between the connection points T and U, the cathode terminal of the Zener diode ZD1 is connected to the connection point T, and the anode terminal of the Zener diode ZD4 is connected. It is only necessary to connect to the point U, connect the anode terminal of the Zener diode ZD1 and the cathode terminal of the Zener diode ZD4, and connect the reference voltage source.

  10, 12 Input protection circuit, 14 Voltage measurement unit, B1-B3 block, ZD1-ZD4 Zener diode, VS1, VS2 varistor.

Claims (2)

A voltage detection circuit comprising:
A flying capacitor,
First ends for sequentially connecting both ends of a plurality of detected voltage sources connected in series with each other to the flying capacitor and charging the flying capacitor alternately with a reverse polarity by the voltage of the detected voltage source . A group of switches;
A voltage measuring unit;
A pair of second switches for connecting both ends of the flying capacitor to the voltage measuring unit;
An overvoltage protection element that is connected between the pair of second switches and the voltage measurement unit and distributes the storage voltage of the flying capacitor, the first and second elements being connected in series with each other , The first element includes a first Zener diode and a second Zener diode connected in opposite directions, and the second element includes a third Zener diode and a fourth Zener diode connected in opposite directions. The cathode terminal of the first Zener diode is connected to the voltage measuring unit, the anode terminal of the first Zener diode and the anode terminal of the second Zener diode are connected to each other, and the cathode terminal of the second Zener diode is the third terminal. Connected to the cathode terminal of the Zener diode and both to the reference voltage source, The anode terminal of the anode terminal and the fourth zener diode E zener diode are connected to each other, a cathode terminal of the fourth zener diode is connected to the voltage measuring unit, an overvoltage protection device,
A voltage detection circuit comprising: The circuit of claim 1, wherein
The voltage detection circuit according to claim 1, wherein the detected voltage source is a block including one or a plurality of battery cells constituting an assembled battery mounted on a vehicle .

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