JP6328454B2 - Equalization equipment - Google Patents

Description

  The present invention relates to an equalization apparatus.

  In recent years, hybrid vehicles (hereinafter referred to as HEV) and electric vehicles (hereinafter referred to as EV) that are driven by an electric motor have become widespread. These HEVs or EVs are equipped with a high voltage battery for driving an electric motor. This high voltage battery obtains a high voltage by connecting a plurality of secondary battery cells composed of secondary batteries such as nickel-hydrogen batteries and lithium batteries in series.

  In the above-described high voltage battery, the voltage across the unit cell, that is, the state of charge (SOC) varies as charging and discharging are repeated. When the SOC varies in this way, the deterioration of the secondary battery cell proceeds at an accelerated rate, or the amount of available energy decreases. Therefore, a battery circuit in which a Zener diode is connected to each secondary battery cell to equalize the Zener voltage of the Zener diode has been proposed (Patent Document 1).

  In the conventional battery circuit described above, the Zener voltage is fixed to 60% of the full charge voltage or SOC of the secondary battery cell, and equalization is performed by connecting the secondary battery cell to the Zener diode during charging. For this reason, in the conventional battery circuit, the secondary battery cells can be equalized only at the timing of charging.

  For this reason, the Zener voltage cannot be set to a value that matches the current state of charge of the secondary battery cell, whether it is being charged, or after the end of charging or discharging. .

JP 2010-45963 A

  Therefore, an object of the present invention is to provide an equalizing device that can efficiently equalize by arbitrarily setting a Zener voltage.

  The invention according to claim 1 for solving the above-described problem is characterized in that a voltage across both ends of the plurality of secondary battery cells is obtained by connecting Zener diodes to both ends of the plurality of secondary battery cells connected in series to each other. Is equalized to the Zener voltage of the Zener diode, wherein a plurality of Zener diodes are connected to each of the secondary battery cells and connected to each of the secondary battery cells. The equalizing apparatus includes a switch for making a Zener voltage of the Zener diode to be variable, and switch control means for controlling the switch.

  The invention according to claim 2 is characterized in that the switch control means obtains an average of the voltages at both ends of a plurality of secondary battery cells connected continuously after the completion of charging or discharging, and the plurality of devices connected continuously. 2. The equalization apparatus according to claim 1, wherein the switch is controlled so that a Zener voltage of the Zener diode connected to the secondary battery cell becomes a target value based on the obtained average. Exist.

  According to a third aspect of the present invention, the switch control means is configured such that, during charging, the Zener voltage of the Zener diode becomes a target value based on a maximum value or a full charge voltage of the both-end voltages of the plurality of secondary battery cells. The equalizing apparatus according to claim 1, wherein the switch is controlled.

  The invention according to claim 4 is characterized in that the switch control means controls the switch so that the Zener voltage of the Zener diode increases stepwise during charging. It exists in the conversion device.

  As described above, according to the first aspect of the present invention, a plurality of zener diodes are connected to the secondary battery cells, and the zener voltage of the zener diode is made variable by a switch, so that the zener voltage is arbitrarily set. Can be equalized efficiently.

  According to the second aspect of the present invention, it is possible to equalize the target value based on the average of the voltages at both ends of a plurality of continuously connected secondary battery cells after charging or discharging is completed. Thereby, since the secondary battery cell higher than a target value is discharged and the secondary battery cell lower than a target value is charged by the discharge current, it can equalize efficiently.

  According to the third aspect of the present invention, during charging, it is possible to equalize the maximum value of the voltages across the secondary battery cells or the target value based on the full charge voltage. Thereby, only the secondary battery cell that has not reached the target value can be charged, and the secondary battery cell that has reached the target value is not charged, and deterioration can be reduced.

  According to the fourth aspect of the present invention, the secondary battery cells can be charged while being equalized stepwise by increasing the zener voltage stepwise during charging.

It is a circuit diagram which shows one Embodiment of the equalization apparatus of this invention. It is explanatory drawing for demonstrating the detail of equalization at the time of completion | finish of charge or discharge. It is explanatory drawing for demonstrating the detail of equalization during charge. It is a graph which shows the relationship between charging time and a target value. It is a circuit diagram which shows the equalization apparatus of this invention in other embodiment.

(First embodiment)
Hereinafter, the equalization apparatus of the present invention in the first embodiment will be described with reference to FIG. FIG. 1 is a circuit diagram showing an embodiment of the equalization apparatus of the present invention. As shown in FIG. 1, the equalizing device 1 is a device that equalizes the voltage across the secondary battery cells C <b> 1 to Cn connected in series with each other. In the present embodiment, the secondary battery cells C1 to Cn are configured from one secondary battery, but may be configured from a plurality of secondary batteries.

  The plurality of secondary battery cells C1 to Cn are used as a power source of an electric motor in, for example, an HEV or EV that uses an electric motor (not shown) as a travel drive source, and electric motors are provided at both ends as necessary. Are connected as a load, and an alternator or the like (not shown) is connected as a charger as required.

  The equalizing apparatus 1 includes a plurality of Zener units U11 to U1n, a plurality of switch units U21 to U2n, and a microcomputer 2. The Zener units U11 to U1n are provided for each of the secondary battery cells C1 to Cn, and are configured by a plurality of Zener diodes ZD respectively connected to both ends of the secondary battery cells C1 to Cn.

  In the present embodiment, the Zener units U11 to U1n are each composed of six Zener diodes ZD connected in parallel to each other. That is, six Zener diodes ZD are connected to each of the secondary battery cells C1 to Cn. These six Zener diodes ZD have different Zener voltages.

  The switch units U21 to U2n are provided for each of the secondary battery cells C1 to Cn, and a plurality of switches SW for changing the Zener voltage of the Zener diode ZD connected to each of the secondary battery cells C1 to Cn. It is composed of The switch SW is connected in series to each of the six Zener diodes ZD constituting each of the units U11 to U1n. That is, in the present embodiment, each of the switch units U21 to U2n is composed of six switches SW.

  The microcomputer 2 includes a known CPU, ROM, RAM, and the like. The microcomputer 2 functions as switch control means, and switches the Zener diode ZD connected to the secondary battery cells C1 to Cn by controlling on / off of the switch SW. Thereby, the Zener voltage of the Zener diode ZD connected to the secondary battery cells C1 to Cn becomes variable. Moreover, the both-ends voltage of each secondary battery cell C1-Cn which the voltage detection part which is not shown in figure detected by the microcomputer 2 is supplied.

  Next, the operation of the equalization apparatus 1 having the above configuration will be described with reference to FIG. Each time the microcomputer 2 finishes charging or discharging of the secondary battery cells C1 to Cn and is in a state of neither being discharged nor charged, the voltage detection unit (not shown) causes the voltage across each of the secondary battery cells C1 to Cn. Is detected.

  Next, the microcomputer 2 determines whether or not there are variations in the secondary battery cells C1 to Cn from the detection result of the both-end voltages. As an example of the variation determination, the microcomputer 2 determines that there is variation if the difference between the lowest value and the highest value among the voltages at both ends of the secondary battery cells C1 to Cn is equal to or greater than a certain value. If there is, it is determined that there is no variation.

  If the microcomputer 2 determines that there is a variation, the microcomputer 2 obtains the average of the voltage across the secondary battery cells C1 to Cn from the detection result of the voltage across the both ends, and sets the obtained average as a target value for equalization. Then, the microcomputer 2 performs on / off control of the switch SW so that the Zener voltage of the Zener diode ZD connected to both ends of each of the secondary battery cells C1 to Cn becomes the target value.

  Explaining in detail the on / off control of the switch SW, the microcomputer 2 turns on the switch SW connected in series with the Zener diode ZD that constitutes each of the Zener units U11 to U1n so that the Zener voltage is close to the target value. Then, the other switches SW are turned off. The microcomputer 2 maintains the on / off state of the switch SW until, for example, charging or discharging is started or periodically monitoring the voltage across the secondary battery cells C1 to Cn until the variation is eliminated. .

  As a result, the secondary battery cells C1 to Cn having both end voltages higher than the average are clamped at the Zener voltage (= average) and discharged. The discharge current at this time is the lower secondary battery cell C1 (in this embodiment, the negative side of the secondary battery cells C1 to Cn is the lower side and the positive side of the secondary battery cells C1 to Cn is the upper side). To Cn, the secondary battery cells C1 to Cn having both-end voltages lower than the average are charged. As a result, variations in the secondary battery cells C1 to Cn are reduced.

  Details of equalization at the end of charging or discharging will be described with reference to FIG. In FIG. 2, the case where the four secondary battery cells C1 to C4 are equalized to an average is illustrated for simplicity of explanation. First, as shown in FIG. 2A, the voltage across the secondary battery cell C1 is lower than the average, the voltage across the secondary battery cell C2 is equal to the average, and the voltage across the secondary battery cells C3 and C4 is A case where the average is higher than the average will be described.

  In the case shown in FIG. 2A, the secondary battery cells C3 and C4 having a voltage at both ends higher than the average are clamped to the average by the Zener diode ZD and discharged. The discharge current of the secondary battery cell C4 is supplied to the secondary battery cells C3 to C1 lower than itself, but the secondary battery cells C3 and C2 are not charged because they are clamped by the Zener diode ZD. On the other hand, the secondary battery cell C1 having a lower-end voltage than the average is not charged by the Zener diode ZD and is charged.

  Further, the discharge current of the secondary battery cell C3 is supplied to the secondary battery cells C2 and C1 lower than itself, but similarly, the secondary battery cell C2 is not charged and the secondary battery cell C1 is charged. The That is, the energy stored in the secondary battery cells C3 and C4 having a higher voltage at both ends than the average can be transferred to the secondary battery cell C1 having a lower voltage than the average, and the secondary battery cells C1 to C4 are wasted. It is possible to equalize more efficiently.

  Next, as shown in FIG. 2B, the case where the voltage across the secondary battery cells C1, C2, C4 is higher than the average and the voltage across the secondary battery cell C3 is lower than the average will be described. In the case shown in FIG. 2 (B), the secondary battery cells C1, C2, and C4 whose end-to-end voltage is higher than the average are clamped to the average by the Zener diode ZD and discharged. The discharge current of the secondary battery cell C4 is supplied to the secondary battery cells C3 to C1 lower than itself, but the secondary battery cells C1 and C2 are not charged because they are clamped by the Zener diode ZD. On the other hand, the secondary battery cell C3 having a voltage at both ends lower than the average is not clamped by the Zener diode ZD and is charged. In this case, since the secondary battery cells C1 and C2 do not have a cell having a higher end voltage than the average below them, other cells cannot be charged by the discharge current, but the secondary battery cell C4 Since the secondary battery cell C3 can be charged with the discharge current, similarly, equalization can be performed efficiently.

  According to the above-described first embodiment, a plurality of zener diodes ZD are connected to the secondary battery cells C1 to Cn, and the zener voltage of the zener diode ZD is made variable by the switch SW, thereby arbitrarily setting the zener voltage. And can be equalized efficiently.

  Moreover, according to 1st Embodiment mentioned above, after charge or discharge is complete | finished, a Zener voltage is set and equalized to the target value based on the average of the both-ends voltage of the some secondary battery cell C1-Cn. be able to. Thereby, the secondary battery cells C1 to Cn that are higher than the target value are discharged, and the secondary battery cells C1 to Cn that are lower than the target value are charged by the discharge current, so that equalization can be performed efficiently.

  According to the above-described embodiment, the average is set as the target value when equalization is performed after charging or discharging is finished, but the present invention is not limited to this. When equalization is performed after charging or discharging is completed, a target value may be set to a value based on an average. For example, an average + α or an average −α (α is a predetermined value) is set as a target value. Is also possible.

(Second Embodiment)
Next, the equalization apparatus 1 in 2nd Embodiment is demonstrated. According to the first embodiment described above, the equalization is performed every time charging or discharging ends, but the present invention is not limited to this. It is also possible to equalize during charging. The operation at this time will be described below.

  If the secondary battery cells C1 to Cn are being charged, the microcomputer 2 detects the voltage across the secondary battery cells C1 to Cn by a voltage detector (not shown). Next, the microcomputer 2 determines whether or not there are variations in the secondary battery cells C1 to Cn from the detection result of the both-end voltages.

  If the microcomputer 2 determines that there is a variation, the microcomputer 2 obtains the maximum value among the voltages across the secondary battery cells C1 to Cn from the detection result of the both-ends voltage, and sets the obtained maximum value as a target value for equalization. Then, the microcomputer 2 performs on / off control of the switch SW so that the Zener voltage of the Zener diode ZD connected to both ends of the secondary battery cells C1 to Cn becomes the target value.

  Explaining in detail the on / off control of the switch SW, the microcomputer 2 turns on the switch SW connected in series with the Zener diode ZD that constitutes each of the Zener units U11 to U1n so that the Zener voltage is close to the target value. Then, the other switches SW are turned off. The microcomputer 2 maintains the on / off state of the switch SW until, for example, charging ends or periodically monitors the voltage across the secondary battery cells C1 to Cn until the variation is eliminated.

  Thereby, during charge, it can equalize to the highest value of the both-ends voltage of a plurality of secondary battery cells C1-Cn. As a result, only the secondary battery cells C1 to Cn that have not reached the maximum value can be charged, and the secondary battery cells C1 to Cn that have reached the maximum value are not charged, thereby reducing deterioration. .

  The details of the equalization during charging will be described with reference to FIG. In FIG. 3, the case where the three secondary battery cells C1 to C3 are equalized to the maximum value is illustrated for the sake of simplicity. First, as shown in FIG. 3, the case where the both-ends voltage of the secondary battery cell C1 is the highest value and the both-ends voltage of the secondary battery cell C3 is lower than the secondary battery cell C2 will be described.

  Although a charging current is supplied to the secondary battery cells C1 to C3 by a charger (not shown), the secondary battery cell C1 is not charged because it is clamped by the Zener diode ZD, and remains at the maximum value. On the other hand, the secondary battery cells C2 and C3 are charged. As a result of the charging, when the secondary battery cell C2 reaches the maximum value before the secondary battery cell C3, it is clamped by the Zener diode ZD and is not charged, and the maximum value is maintained. Finally, when the secondary battery cell C3 reaches the maximum value, it is clamped by the Zener diode ZD and is not charged, and the voltage across the secondary battery cells C1 to C3 is equalized to the maximum value.

  According to 2nd Embodiment mentioned above, during charge, it can equalize to the target value based on the highest value of the both-ends voltage of the some secondary battery cell C1-Cn. Thereby, only the secondary battery cells C1 to Cn that have not reached the target value can be charged, and the secondary battery cells C1 to Cn that have reached the target value are not charged, and the deterioration can be reduced. .

  In addition, according to 2nd Embodiment mentioned above, when equalizing during charge, although the maximum value was made into the target value, it is not restricted to this. When equalization is performed during charging, the target value may be set to a value based on the maximum value. For example, the maximum value + α may be set to the target value. Furthermore, it is conceivable to set the full charge voltage of the secondary battery cells C1 to Cn, 60% of the full charge voltage, or the like as a target value.

  Further, according to the above-described embodiment, the target value is fixed to the maximum value or the full charge voltage of the secondary battery cells C1 to Cn during charging, but is not limited thereto. For example, as shown in FIG. 4, it is conceivable that the switch SW is turned on / off so that the target value is increased step by step at a predetermined time to reach the maximum value or the full charge voltage. According to this, the secondary battery cells C1 to Cn can reach the maximum value or the full charge voltage at the same timing without reaching the maximum value or the full charge voltage at a disjoint timing, and a more uniform state can be achieved. Can keep long. In this case, the target value is increased not only at a predetermined time interval, but also by detecting the voltage across the secondary battery cells C1 to Cn and setting the voltage across all the secondary battery cells C1 to Cn. On the other hand, the target value may be increased when approaching within a predetermined range.

(Third embodiment)
Next, the equalization apparatus 1 of the present invention in the third embodiment will be described. According to the first embodiment described above, equalization is performed only at the end of charging or discharging, and according to the second embodiment, only during charging, the equalization is performed, but this is not a limitation. For example, based on the voltage across the secondary battery cells C1 to Cn at the end of charging or discharging, it is possible to select whether to equalize at the end of charging or discharging or to perform equalization at the next charging. Good. The operation at this time will be described below.

  First, the microcomputer 4 detects the voltage across the secondary battery cells C1 to Cn by a voltage detector (not shown) every time charging or discharging ends and the battery is not discharged or charged. Whether or not has occurred. If the microcomputer 4 determines that the variation has occurred, the Zener voltage of the secondary battery cells C1 to Cn is now determined (at the end of charging or discharging) based on the voltage across the secondary battery cells C1 to Cn at that time. Decide whether to set the average value of the voltage at both ends to equalize or not equalize now and set the Zener voltage to the highest value of the voltage across the secondary battery cells C1 to Cn at the next charging To do.

  An example of this determination will be described. For example, consider the case where the voltage across the secondary battery cells C1 to Cn gradually increases as it becomes lower as shown in FIG. 3 at the end of charging or discharging. In such a case, when the Zener voltage is set to an average value and equalization is performed, the secondary battery cells C1 to Cn having a higher end voltage than the average are merely discharged, and the lower secondary battery cells C1 to Cn are discharged. Since it is not used at all for charging, it is inefficient. Therefore, in the case shown in FIG. 4, it is determined that the equalization is performed by setting the Zener voltage to the highest value in the next charging without performing equalization at the end of charging or discharging.

  If the microcomputer 4 determines that the charge is equalized at the end of charging or discharging in this determination, the microcomputer 4 sets the Zener voltage to an average value and performs equalization as in the first embodiment. On the other hand, if it is determined to be equal during the next charge, the Zener voltage is set to the highest value during the next charge, and equalization is performed as in the second embodiment.

  In addition, according to 1st-3rd embodiment mentioned above, although several Zener diode ZD which comprises Zener unit U11-U1n was mutually connected in parallel, it is not restricted to this. For example, as shown in FIG. 5, a plurality of Zener diodes ZD may be connected in series to each of the secondary battery cells C1 to Cn. In this case, the switch SW is provided between the adjacent Zener diodes ZD and connects adjacent Zener diodes ZD or the lower side (one side) of the adjacent Zener diodes ZD and the positive terminals of the secondary battery cells C1 to Cn. (One end) is connected or switched. Thereby, the number of Zener diodes ZD connected to the secondary battery cells C1 to Cn can be controlled to make the Zener voltage variable.

  Further, for example, when an abnormality occurs in the secondary battery cells C1 to Cn, such as when the temperature of the secondary battery cells C1 to Cn suddenly rises or the mounted vehicle collides, the Zener voltage is set to the secondary battery cells C1 to Cn. Alternatively, the secondary battery cells C1 to Cn other than the lowest value may be discharged to perform equalization quickly.

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

1 Equalizing device 2 Microcomputer (switch control means)
C1 to Cn Secondary battery cell ZD Zener diode SW switch

Claims (4)

An equalizing device that equalizes the voltage across the plurality of secondary battery cells to the Zener voltage across the plurality of secondary battery cells by connecting Zener diodes to both ends of the plurality of secondary battery cells connected in series with each other. And
A plurality of the zener diodes are connected to each of the secondary battery cells;
A switch for making the Zener voltage of a Zener diode connected to each of the secondary battery cells variable;
Switch control means for controlling the switch;
An equalizing device comprising: The switch control means obtains an average of both-end voltages of a plurality of secondary battery cells connected continuously after charging or discharging ends, and is connected to the plurality of secondary battery cells connected continuously. 2. The equalization apparatus according to claim 1, wherein the switch is controlled so that a Zener voltage of the Zener diode becomes a target value based on the obtained average. The switch control means controls the switch so that a Zener voltage of the Zener diode becomes a target value based on a maximum value or a full charge voltage of both terminals of the plurality of secondary battery cells during charging. The equalizing apparatus according to claim 1. The equalization apparatus according to claim 1, wherein the switch control unit controls the switch so that a Zener voltage of the Zener diode increases stepwise during charging.

Images