JP2014003737A - Charge controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge controller capable of shortening a charging time of a battery at low temperature.SOLUTION: When a high-voltage battery 12 is charged, charging power for the high-voltage battery 12 is maintained at first predetermined power W1, and first constant-power charge control for charging the high-voltage battery 12 is performed until voltage of the high-voltage battery 12 (closed circuit voltage CCV) reaches first target voltage V1 (such as a target value of open circuit voltage OCV). Then charging voltage for the high-voltage battery 12 is maintained at predetermined voltage Va, and constant-voltage charge control for charging the high-voltage battery 12 is performed until the charging power for the high-voltage battery 12 is reduced to a determination threshold Wa. Furthermore, the charging power for the high-voltage battery 12 is maintained at second predetermined power W2 which is lower than the first predetermined power W1, and second constant-power charge control for charging the high-voltage battery 12 is performed until the voltage of the high-voltage battery 12 reaches second target voltage V2 (such as a target value of the closed circuit voltage CCV).

Description

  The present invention relates to a charging control device that controls charging of a battery.

  In recent years, hybrid vehicles and electric vehicles equipped with a motor as a power source for vehicles have attracted attention because of the social demand for low fuel consumption and low exhaust emissions. As charging control when charging a battery mounted on such a vehicle from an external power source, for example, as described in Patent Document 1 (Japanese Patent Laid-Open No. 10-51970), the charging current of the battery is set at a predetermined speed. After performing the trial charge that is increased in step 1, the main charge is executed to decrease the charge current every time the voltage of the battery reaches a predetermined charge current switching voltage.

JP-A-10-51970

  By the way, as shown in FIG. 6 and FIG. 7, the present applicant first maintains the battery charging power at a relatively high first predetermined power W1 (a constant value) when charging the battery. After executing the first constant power charging control for charging until the battery voltage (closed circuit voltage CCV) rises to the first target voltage V1 (for example, the target value of the open circuit voltage OCV), the charging power of the battery is The battery voltage (closed circuit voltage CCV) is the second target voltage in the second constant power charging control for charging the battery while maintaining the second predetermined power W2 (constant value) lower than the first predetermined power W1. We are researching a system that allows charging to near full charge while preventing overcharge by executing until it rises to V2 (for example, the target value of the closed circuit voltage CCV). The problem was revealed.

In general, the relationship between the closed circuit voltage CCV and the open circuit voltage OCV when charging a battery is expressed by the following equation using an internal voltage drop IR (voltage drop due to internal resistance) and a polarization voltage Vx (voltage drop due to polarization action) Can be represented by
CCV = OCV + (IR + Vx)

  When the temperature is low, the value of (IR + Vx) in the above equation increases, and the difference between the closed circuit voltage CCV and the open circuit voltage OCV tends to increase. For this reason, when the temperature is low (for example, at -25 ° C.), the closed circuit voltage CCV is low when the open circuit voltage OCV is still low and the amount of charging power is low during the first constant power charging control. The first constant power charging control is terminated when the first target voltage V1 is reached, and the amount of charging power by the first constant power charging control is smaller than that at room temperature (for example, at 25 ° C.). As a result, the execution time of the second constant power charging control for charging with lower charging power than that of the first constant power charging control is considerably increased, and the battery charging time (time required from the start of charging to the end of charging) is increased. There is a problem that becomes longer.

  Moreover, in the technique of the above-mentioned Patent Document 1, in order to reduce the charging current every time the voltage of the battery reaches the charging current switching voltage during the main charging, it is necessary to perform complicated current control (for example, feedback control).

  Therefore, the problem to be solved by the present invention is to provide a charge control device capable of shortening the charging time of the battery at a low temperature without performing complicated current control.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a charge control device that controls charging of a battery (12), wherein the charging power of the battery (12) is maintained at a first predetermined power. The first constant power charge control means (23) for executing the first constant power charge control for charging the battery (12) until the voltage of the battery (12) rises to the first target voltage, and the first constant power charge After the control is executed, the constant voltage charging control for charging the battery (12) while maintaining the charging voltage of the battery (12) at a predetermined voltage is executed until the charging power of the battery (12) decreases to a predetermined determination threshold. After the voltage charging control means (23) and the constant voltage charging control are executed, the battery (12) is charged while maintaining the charging power of the battery (12) at a second predetermined power lower than the first predetermined power. Second constant power charging system The one in which the voltage of the battery (12) is configured to include a second constant power charging control means for performing (23) until the rise in the high second target voltage than the first target voltage.

  In this configuration, when charging the battery, first, the first constant power charging control for charging the battery while maintaining the charging power of the battery at the first predetermined power is performed, and the battery voltage is set to the first target voltage. Run until it rises. Thereafter, constant voltage charging control for charging the battery while maintaining the charging voltage of the battery at a predetermined voltage is executed until the charging power of the battery drops to a predetermined determination threshold, and then the charging power of the battery is set to a second predetermined power. The second constant power charge control for charging the battery while maintaining the electric power is executed until the voltage of the battery rises to the second target voltage.

  In this case, in the constant voltage charge control (see FIG. 2) executed between the first constant power charge control and the second constant power charge control, the charge power is gradually decreased from the vicinity of the first predetermined power. Since it can be reduced to the vicinity of the second predetermined power, the amount of charging power can be increased faster than the second constant power charging control in which charging is performed with the second predetermined power.

  For this reason, in the system in which the second constant power charging control is performed after the constant voltage charging control is performed after the first constant power charging control is performed, the amount of charging power by the first constant power charging control is low at low temperatures. Even in such a case, it becomes possible to increase the amount of charging power relatively quickly by the constant voltage charging control, and a system for switching from the first constant power charging control to the second constant power charging control (the constant voltage charging control is not executed). Compared with the system), the battery charging time at low temperature (time required from the start of charging to the end of charging) can be shortened.

  In addition, the constant voltage charge control has an advantage that complicated current control (for example, feedback control) does not need to be performed because the charging current changes with the course.

FIG. 1 is a diagram showing a schematic configuration of a vehicle charge control system according to an embodiment of the present invention. FIG. 2 is a time chart for explaining the charging control of this embodiment. FIG. 3 is a time chart showing the behavior of the charging voltage and charging current in the charging control of this embodiment. FIG. 4 is a flowchart showing the flow of processing of the charging control routine of this embodiment. FIG. 5 is a time chart for explaining the effect of the charging control of this embodiment. FIG. 6 is a time chart (part 1) for explaining the charge control of the comparative example. FIG. 7 is a time chart (part 2) for explaining the charge control of the comparative example.

Hereinafter, an embodiment embodying a mode for carrying out the present invention will be described.
First, a schematic configuration of a charging control system for a vehicle (for example, a plug-in hybrid vehicle or an electric vehicle that can be charged from a power source outside the vehicle) will be described with reference to FIG.

  A motor 11 serving as a power source for the vehicle and a high voltage battery 12 (battery) for supplying electric power to the motor 11 are mounted. In addition, a charger 16 that converts AC power of the commercial power supply 13 into DC power is connected to the external power supply connection portion 15 connected via a charging cable 14 to a commercial power supply 13 (for example, AC100V power supply or AC200V power supply) outside the vehicle. The power supply lines L1 and L2 that are connected and connect the charger 16 and the high voltage battery 12 are provided with a charging relay and a main relay (both not shown).

  Further, a battery voltage sensor 17 that detects a terminal voltage of the high-voltage battery 12 and a battery current sensor 24 that detects a current are connected to the power supply lines L1 and L2. The high voltage battery 12, the battery voltage sensor 17, the battery current sensor 24, and the like may be housed in a battery pack.

  On the other hand, the charger 16 detects a charging voltage sensor 18 that detects a charging voltage of the high voltage battery 12 (output voltage of the charger 16) and a charging current of the high voltage battery 12 (output current of the charger 16). A charging current sensor 19 is incorporated. The charging voltage and charging current may be detected not only by direct sensor detection but also by estimation. In addition, it is good also as a structure which provided the charging voltage sensor 18 and the charging current sensor 19 in the exterior of the charger 16. FIG. The charging power of the high voltage battery 12 (output power of the charger 16) can be obtained from the charging voltage detected by the charging voltage sensor 18 and the charging current detected by the charging current sensor 19.

  In addition, an inverter 20, a DC-DC converter 21, and the like are connected to the power supply lines L 1 and L 2, and the motor 11 is connected to the inverter 20. Further, an auxiliary battery 22 (low voltage battery) is connected to the DC-DC converter 21, and various electrical components (not shown) are connected to the auxiliary battery 22.

  The charger 16, the inverter 20, the converter 21, and the like described above are controlled by an electronic control unit (hereinafter referred to as “ECU”) 23. The ECU 23 is mainly composed of a microcomputer, and executes charge control routine of FIG. 4 described later, thereby executing charge control of the high voltage battery 12 as follows.

  As shown in FIG. 2, when charging the high voltage battery 12, first, the charging power of the high voltage battery 12 (output power of the charger 16) is maintained at the first predetermined power W1 (a constant value). The first constant power charging control for charging the high voltage battery 12 is executed until the voltage of the high voltage battery 12 (closed circuit voltage CCV) rises to the first target voltage V1 (for example, the target value of the open circuit voltage OCV). To do.

  Thereafter, constant voltage charging control for charging the high voltage battery 12 while maintaining the charging voltage of the high voltage battery 12 (output voltage of the charger 16) at a predetermined voltage Va (a constant value) is performed. Until the value falls to a predetermined determination threshold value Wa. During this constant voltage charging control, the open circuit voltage OCV increases and the charging current decreases as the charging power increases (see FIG. 3). Further, the internal voltage drop IR decreases due to the decrease in the charging current, and the polarization voltage Vx decreases as the charging current decreases and the charging time elapses.

  Thereafter, the second constant power charging control for charging the high voltage battery 12 while maintaining the charging power of the high voltage battery 12 at a second predetermined power W2 (a constant value) lower than the first predetermined power W1 is performed. The high voltage battery 12 is executed until the voltage of the high voltage battery 12 (closed circuit voltage CCV) rises to a second target voltage V2 (for example, a target value of the closed circuit voltage CCV) higher than the first target voltage V1. End charging.

  If the constant voltage charging control is executed from the beginning when charging the high voltage battery 12, the charging power may become too large and exceed the allowable limit of the charger 16, in order to prevent this. This requires the use of a large charger with a high tolerance limit.

  In this respect, in the present embodiment, when charging the high voltage battery 12, first, the first constant power charging control is executed, so that the charging power is prevented from exceeding the allowable limit value of the charger 16. Therefore, it is not necessary to use a large charger having a high tolerance limit.

  In the constant voltage charge control executed between the first constant power charge control and the second constant power charge control, the charge power is gradually decreased from the vicinity of the first predetermined power W1 to obtain the second predetermined power. Since it can be reduced to near W2, the charge power amount can be increased faster than the second constant power charge control charged with the second predetermined power W2, and the charge current is increased as the charge power amount increases. Therefore, it is not necessary to perform feedback control.

  By the way, in constant voltage charge control, the charge current decreases as the amount of charge increases, and the charge power decreases. Low power charging is performed by using a region (for example, a region lower than the second predetermined power W2), and the execution time of the constant voltage charging control becomes considerably long. The charging time (time required from the start of charging to the end of charging) becomes longer.

  In this regard, in this embodiment, the constant voltage charging control is executed until the charging power of the high voltage battery 12 decreases to the determination threshold value Wa, and the second voltage from the constant voltage charging control is reached when the charging power decreases to the determination threshold value Wa. In order to switch to the constant power charge control, the second constant power charge control approaches the full charge while avoiding the low power charge by the constant voltage charge control and preventing the constant voltage charge control from executing for a long time. Can do.

  Further, by switching from the constant voltage charge control to the second constant power charge control, it is possible to monitor the increase in the voltage of the high voltage battery 12 (closed circuit voltage CCV) and determine the completion of charging. When charging is to be terminated with constant voltage charging control, the charging voltage is maintained at a constant value with constant voltage charging control, so charging completion cannot be determined with voltage. There is a need to do. However, with constant voltage charge control, the charge current decreases only slightly as it approaches full charge, so even if the charge current is monitored, whether charging is complete (whether it has been charged to near full charge) is accurate. It is difficult to judge well.

  As in this embodiment, when the charging power decreases to the determination threshold Wa, the voltage of the high voltage battery 12 (closed circuit voltage CCV) increases by switching from the constant voltage charging control to the second constant power charging control. Therefore, by determining whether the voltage of the high-voltage battery 12 has reached the second target voltage V2, it is possible to accurately determine whether charging is complete (whether it has been fully charged). Can be judged well.

The charging control of the high voltage battery 12 described above is executed by the ECU 23 according to the charging control routine of FIG. The processing contents of this routine will be described below.
The charge control routine shown in FIG. 4 is repeatedly executed at a predetermined period during the power-on period of the ECU 23. When this routine is started, first, at step 101, it is determined whether or not there is a charge request, for example, depending on whether or not a charge request signal is input after the charging cable 14 is connected. If it is determined in step 101 that there is no charge request, this routine is terminated without executing the processing related to the charge control in step 102 and subsequent steps.

  On the other hand, if it is determined in step 101 that there is a charge request, the process proceeds to step 102, and the first constant power charging control is executed. In the first constant power charging control, charging is performed so as to charge the high voltage battery 12 while maintaining the charging power of the high voltage battery 12 (output power of the charger 16) at the first predetermined power W1 (a constant value). The device 16 is controlled. Here, the first predetermined power W1 is set to, for example, the maximum value of the output power of the charger 16 or a value slightly lower (for example, 1 to 3 kW).

Thereafter, the process proceeds to step 103, where it is determined whether or not the voltage of the high voltage battery 12 (closed circuit voltage CCV) detected by the battery voltage sensor 17 is equal to or higher than the first target voltage V1. Here, the first target voltage V1 is set to a target value of the open circuit voltage OCV, for example.
If it is determined in step 103 that the voltage of the high-voltage battery 12 is lower than the first target voltage V1, the process returns to step 102 and the first constant power charging control is continued.

  Thereafter, when it is determined in step 103 that the voltage of the high-voltage battery 12 has become equal to or higher than the first target voltage V1, the process proceeds to step 104 and constant voltage charging control is executed. In this constant voltage charging control, the charger 16 is controlled so as to charge the high voltage battery 12 while maintaining the charging voltage of the high voltage battery 12 (the output voltage of the charger 16) at a predetermined voltage Va (a constant value). Here, the predetermined voltage Va is, for example, the charge voltage of the high voltage battery 12 at the end of the first constant power charge control (when the voltage of the high voltage battery 12 reaches the first target voltage V1) or the vicinity thereof. The voltage is set to

Thereafter, the process proceeds to step 105, where the charging power of the high voltage battery 12 (the output power of the charger 16) is obtained from the charging voltage detected by the charging voltage sensor 18 and the charging current detected by the charging current sensor 19, and the high voltage battery It is determined whether or not the 12 charging power is equal to or less than the determination threshold value Wa. Here, the determination threshold value Wa is set to, for example, the second predetermined power W2 or power in the vicinity thereof.
If it is determined in step 105 that the charging power of the high voltage battery 12 is higher than the determination threshold value Wa, the process returns to step 104 and the constant voltage charging control is continued.

  Thereafter, when it is determined in step 105 that the charging power of the high voltage battery 12 has become equal to or less than the determination threshold value Wa, the process proceeds to step 106, and second constant power charging control is executed. In the second constant power charging control, charging is performed so that the high voltage battery 12 is charged while maintaining the charging power of the high voltage battery 12 (output power of the charger 16) at the second predetermined power W2 (a constant value). The device 16 is controlled. Here, the second predetermined power W2 is set to a value (for example, 500 W) lower than the first predetermined power W1.

Thereafter, the routine proceeds to step 107, where it is determined whether or not the voltage of the high voltage battery 12 (closed circuit voltage CCV) detected by the battery voltage sensor 17 has become equal to or higher than the second target voltage V2. Here, the second target voltage V2 is set to a target value of the closed circuit voltage CCV, for example.
If it is determined in step 107 that the voltage of the high-voltage battery 12 is lower than the second target voltage V2, the process returns to step 106 and the second constant power charging control is continued.

  Thereafter, when it is determined in step 107 that the voltage of the high voltage battery 12 has become equal to or higher than the second target voltage V2, it is determined that the charging of the high voltage battery 12 has been completed (charged to near full charge). Then, the process proceeds to step 108 and the charging of the high voltage battery 12 is finished.

  In this case, the processing of steps 102 and 103 serves as the first constant power charge control means in the claims. Further, the processing in steps 104 and 105 serves as a constant voltage charge control means in the claims, and the processing in steps 106 and 107 serves as second constant power charge control means in the claims. Fulfill.

  In the present embodiment described above, when charging the high voltage battery 12, first, the first constant charge for charging the high voltage battery 12 while maintaining the charging power of the high voltage battery 12 at the first predetermined power W1. The power charging control is executed until the voltage of the high voltage battery 12 rises to the first target voltage V1. Then, after executing the constant voltage charging control for charging the high voltage battery 12 while maintaining the charging voltage of the high voltage battery 12 at the predetermined voltage Va, until the charging power of the high voltage battery 12 decreases to the determination threshold value Wa, In the second constant power charging control for charging the high voltage battery 12 while maintaining the charging power of the high voltage battery 12 at the second predetermined power W2, the voltage of the high voltage battery 12 rises to the second target voltage V2. Run until.

  In this case, in the constant voltage charging control executed between the first constant power charging control and the second constant power charging control, the charging power is gradually decreased from the vicinity of the first predetermined power W1 to obtain the second predetermined power. Since the electric power can be reduced to near the electric power W2, the amount of charging electric power can be increased earlier than the second constant electric power charging control in which charging is performed with the second predetermined electric power W2.

  For this reason, in the system in which the second constant power charging control is performed after the constant voltage charging control is performed after the first constant power charging control is performed as in the present embodiment illustrated in FIG. Even when the amount of charging power by the first constant power charging control sometimes decreases, the charging power amount can be increased relatively quickly by the constant voltage charging control, as in the comparative example shown in FIG. Compared with a system that switches from the first constant power charging control to the second constant power charging control (a system that does not execute constant voltage charging control), the charging time of the high voltage battery 12 at low temperatures can be shortened. In addition, the constant voltage charge control has an advantage that complicated current control (for example, feedback control) does not need to be performed because the charging current changes with the course.

  In the above embodiment, the voltage of the high voltage battery 12 is detected by the voltage sensor 17 provided on the high voltage battery 12 side. However, the present invention is not limited to this, and the voltage sensor 18 provided on the charger 16 side is used. The voltage of the high voltage battery 12 may be detected.

  In the above embodiment, the charging power of the high voltage battery 12 is obtained from the charging voltage detected by the voltage sensor 18 provided on the charger 16 side and the charging current detected by the current sensor 19 provided on the charger 16 side. However, the present invention is not limited to this, and the charging power of the high voltage battery 12 is obtained from the voltage detected by the voltage sensor 17 provided on the high voltage battery 12 side and the current detected by the current sensor provided on the high voltage battery 12 side. Anyway.

  In the above embodiment, the present invention is applied to the battery charge control system that supplies power to the power source (motor) of the vehicle. However, the present invention is not limited to this, and the present invention is applicable to various battery charge control systems. Can be applied.

  DESCRIPTION OF SYMBOLS 11 ... Motor, 12 ... High voltage battery (battery), 13 ... Commercial power supply, 16 ... Charger, 17 ... Battery voltage sensor, 18 ... Charge voltage sensor, 19 ... Charge current sensor, 23 ... ECU (1st constant power) Charge control means, constant voltage charge control means, second constant power charge control means)

Claims (2)

In the charging control device for controlling the charging of the battery (12),
In the first constant power charging control for charging the battery (12) while maintaining the charging power of the battery (12) at a first predetermined power, the voltage of the battery (12) rises to the first target voltage. First constant power charge control means (23) to execute until
After the execution of the first constant power charging control, the charging power of the battery (12) is set to a constant voltage charging control for charging the battery (12) while maintaining the charging voltage of the battery (12) at a predetermined voltage. Constant voltage charge control means (23) to be executed until it falls to the determination threshold value,
Second constant power charging for charging the battery (12) while maintaining the charging power of the battery (12) at a second predetermined power lower than the first predetermined power after the execution of the constant voltage charging control. And second constant power charge control means (23) for executing control until the voltage of the battery (12) rises to a second target voltage higher than the first target voltage. Charging control device.   The charging control device according to claim 1, wherein the battery is a battery that supplies electric power to a power source of a vehicle.

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