JP2019097353A - Control device of power generator - Google Patents

Abstract

To provide a control device of a power generator capable of suppressing to occur a situation where charge polarization occurs in a battery at the time of regenerative control.SOLUTION: A CPU 42 calculates a charge rate SOC of a battery 30 on the basis of a charge/discharge current I, and calculates a power generation instruction voltage of an alternator 20 as an operation amount for feedback control of the charge rate SOC to a target charge rate SOC*. The CPU 42 calculates a lower limit guard value of the power generation instruction voltage on the basis of the charge rate SOC so as to be larger when the charging rate SOC is small than when the value is large. When the operation amount is smaller than the lower limit guard value, the CPU 42 substitutes the lower limit guard value into the power generation instruction voltage.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for a generator whose control object is to convert a rotational power of a crankshaft of an internal combustion engine into electric power and apply an output voltage to a battery.

  For example, if there is a charge history of the battery at the time of deceleration of the vehicle, Patent Document 1 below describes a control device that discharges the battery a certain amount and then raises the output voltage of the alternator (generator) to perform regenerative charging of the battery. It is done. This is intended to eliminate charge polarization by temporarily discharging the battery because the battery has difficulty receiving power due to charge polarization when there is a charge history.

JP 2008-263679 A

  However, in the above case, in order to execute the process of discharging the battery immediately after the start of deceleration, the regenerative energy can not be charged to the battery immediately after the start of deceleration, and it is an improvement in efficiently recovering regenerative energy. There is room for

  In order to solve the above problems, a control device for a generator controls a generator that converts rotational power of a crankshaft of an internal combustion engine into electric power and applies an output voltage to a battery, and targets a charging rate of the battery. Feedback processing for setting the output voltage of the generator as an operation amount for feedback control to the charging rate, lower limit guard value setting processing for setting the lower limit guard value of the output voltage, and output voltage set by the feedback processing Performing a guard process for limiting the value to the lower limit guard value and an operation process for operating the generator to obtain the output voltage subjected to the guard process, wherein the lower limit guard value setting process The lower limit guard value is set to a smaller value as the

  In the above configuration, the lower limit guard value is set to a smaller value as the charging rate is larger. Therefore, when the charging rate is small, it is possible to make the output voltage of the alternator larger than the terminal voltage of the battery. The generated power is charged to the battery. For this reason, it is suppressed that a charge rate becomes small too much. Therefore, compared to the case where the charging rate becomes excessively small, it is possible to suppress the increase in the amount of charge by which the power generated by the generator is charged to the battery by the feedback processing. Also, when the charging rate is large, the output voltage of the alternator can be made smaller than the terminal voltage of the battery. Therefore, it is possible to suppress the case where the battery is excessively charged due to the overshoot of the feedback processing. For this reason, if the lower limit guard value at which the charging rate reaches the target charging rate is set to about the terminal voltage of the battery at which the target charging rate is reached, the charging rate of the battery is significantly lower than the target charging rate. In addition, when the charging rate of the battery exceeds the target charging rate, it is possible to suppress that the power generated by the generator is charged to the battery. Therefore, it is possible to suppress the occurrence of charge polarization occurring in the battery at the time of regenerative control.

The figure which shows the control apparatus and generator concerning one Embodiment. The flowchart which shows the procedure of the process which the control apparatus concerning the embodiment performs. The time chart which shows the knowledge used as the premise of the setting of the lower limit guard value concerning the embodiment. The time chart which shows the effect concerning the embodiment. The time chart which shows the comparative example of the embodiment. The figure explaining another comparative example of the embodiment.

Hereinafter, an embodiment according to a control device for a generator will be described with reference to the drawings.
As shown in FIG. 1, the rotational power of the crankshaft 12 of the internal combustion engine 10 can be transmitted to the rotation shaft 22 of the alternator 20 via, for example, a belt or the like. The output voltage of the alternator 20 is applied to the battery 30. Battery 30 is a lead storage battery having a terminal voltage of, for example, about 12V.

  The control device 40 controls the alternator 20 and controls its control amount (e.g. generated power). The control device 40 refers to the terminal voltage V of the battery 30 detected by the voltage sensor 46 and the charge / discharge current I of the battery 30 detected by the current sensor 48 when controlling the control amount. The control device 40 includes a CPU 42 and a ROM 44, and the CPU 42 executes a program stored in the ROM 44 to execute control of the control amount.

  FIG. 2 shows a part of the process executed by the control device 40. The process shown in FIG. 2 is realized by the CPU 42 repeatedly executing the program stored in the ROM 44 at a predetermined cycle, for example. In the following, the step number is represented by a number to which "S" is added at the beginning.

  In the series of processes shown in FIG. 2, CPU 42 first performs regeneration control to convert the rotational power of crankshaft 12 into electric energy by alternator 20 and charge battery 30 during fuel cut control of internal combustion engine 10. It is determined (S10). When it is determined that the regeneration control is not being performed (S10: NO), the CPU 42 calculates the charging rate SOC (S12). Here, for example, the charging rate SOC may be calculated from the integrated value of the charge / discharge current I. Further, for example, when the absolute value of the charge / discharge current I is equal to or less than a predetermined value, the charging rate SOC may be calculated based on the terminal voltage V. Next, the CPU 42 calculates a feedback voltage dV which is an update amount of an operation amount (feedback operation amount) for feedback control of the charging rate SOC to the target charging rate SOC * (S14). As shown in FIG. 2, the feedback voltage dV has an absolute value smaller than that of the case where the absolute value of the difference between the charging rate SOC and the target charging rate SOC * is small. This setting is intended to suppress large fluctuation of the output voltage of the alternator 20 by feedback control even though the charging rate SOC is near the target charging rate SOC *. Specifically, when the absolute value of the difference is equal to or less than the specified value, the feedback voltage dV is set to zero, and a dead zone in which the update amount of the feedback operation amount is zero is set. The region where the absolute value is relatively small is a weak band where the absolute value of the feedback voltage dV is small.

  Next, the CPU 42 updates the power generation instruction voltage V * by substituting a value obtained by adding the feedback voltage dV to the power generation instruction voltage V * to the power generation instruction voltage V * (S16). That is, in the present embodiment, the power generation instruction voltage V * is set based on the output value of the integral element to which the difference between the charging rate SOC and the target charging rate SOC * is input, and the feedback voltage dV is the integration It is the update amount of the output value of the element.

  Next, the CPU 42 calculates the lower limit guard value VthL of the power generation instruction voltage V * based on the charging rate SOC (S18). The CPU 42 sets the lower limit guard value VthL to a smaller value when the state of charge SOC is large than when it is small. Further, the CPU 42 sets the lower limit guard value VthL when the state of charge SOC is near the target state of charge SOC * or is smaller than the target state of charge SOC * when the state of charge SOC is the target state of charge SOC * The terminal voltage of the battery 30 (for example, open circuit voltage) is set. This is a setting for controlling the charging rate SOC of the battery 30 in the vicinity of the target charging rate SOC * except during regeneration control and the like, and is based on the following findings.

  FIG. 3 shows the transition of the vehicle speed, the power generation instruction voltage V * and the charge / discharge current I. In particular, for the power generation instruction voltage V * and the charge / discharge current I in solid lines, the lower limit guard value VthL is not provided temporarily, The case where the power generation instruction voltage V * calculated in S16 is the actual output voltage of the alternator 20 is exemplified. The sign of the charge / discharge current I is positive on the charge side.

  As shown in FIG. 3, when the power generation instruction voltage V * is set by the integrated value of the feedback voltage dV, the power generation instruction of the alternator 20 is caused even if the charging rate SOC of the battery 30 decreases due to the influence of the dead zone or the weak zone. Since the rise of voltage V * is delayed, the amount of discharge of battery 30 is increased to some extent even after a certain amount of time after time t1 when the vehicle starts traveling. Then, the charging rate SOC greatly decreases with respect to the target charging rate SOC *, so that the charging power of the battery 30 by the alternator 20 rapidly increases at time t2. Therefore, fuel cut control of the internal combustion engine 10 is performed along with the deceleration of the vehicle from time t3 and when regeneration control is performed by the alternator 20, the battery 30 still has the influence of polarization due to charging before time t3. Thus, the charge amount of the battery 30 is reduced. On the other hand, for example, as shown by the alternate long and short dash line in FIG. 3, if the power generation instruction voltage V * after time t1 is raised, the discharge amount of battery 30 can be limited. It is possible to prevent the charging current of the battery 30 from becoming excessively large prior to step S. Therefore, it is possible to reduce the influence of polarization caused by charging before regeneration control at the time of regeneration control.

  In view of such knowledge, in the present embodiment, the excessive decrease in the charging rate SOC caused by setting the power generation instruction voltage V * only from the integrated value of the feedback voltage dV is suppressed by the setting of the lower limit guard value VthL.

  Returning to FIG. 2, the CPU 42 determines whether the power generation instruction voltage V * is smaller than the lower limit guard value VthL (S20). When it is determined that the CPU 42 is smaller than the lower limit guard value VthL (S20: YES), the CPU 42 substitutes the lower limit guard value VthL into the power generation instruction voltage V * (S22). When the process of S22 is completed or when the determination of S20 is negative, the CPU 42 outputs the operation signal MS to the alternator 20 so as to set the output voltage of the alternator 20 to the power generation instruction voltage V *. The operation is performed (S24).

  On the other hand, when it is determined that the regeneration control is being performed (S10: YES), the CPU 42 substitutes the regeneration command voltage VH for the power generation command voltage V * (S26), and shifts to the processing of S24. The CPU 42 sets the initial value of the power generation instruction voltage V * corrected by the feedback voltage dV as the power generation instruction voltage V * immediately before the regeneration control in the process of S16 immediately after the end of the regeneration control. Incidentally, when the process of S24 is completed, the CPU 42 temporarily ends the series of processes shown in FIG.

Here, the operation and effects of the present embodiment will be described.
FIG. 4 shows changes of the vehicle speed, the presence or absence of fuel injection, the power generation instruction voltage V *, the charge ratio SOC, and the charge / discharge current I of the battery 30 according to the present embodiment.

  As shown in FIG. 4, after time t1 when the vehicle starts, the power generation instruction voltage V * rises in accordance with the decrease in the charging rate SOC. Thereby, the discharge of the battery 30 is suppressed. For this reason, since charge polarization of the battery 30 is suppressed, the charge amount of the battery 30 in the regeneration control period from time t2 to t3 can be increased. Thereafter, the discharge of battery 30 is suppressed also in the period up to time t5 where the regenerative control is started again after the idle stop period of time t3 to t4, so charging of the battery before time t5 is also suppressed. Ru. Therefore, the charge polarization of the battery 30 is suppressed, and therefore, the charge amount of the battery 30 in the regeneration control period after time t5 can be increased.

  In FIG. 5, the vehicle speed, the presence or absence of fuel injection, the power generation instruction voltage V *, the charge ratio SOC, and the charge / discharge current I of the battery 30 in the comparative example in which the power generation instruction voltage V * calculated by the process of S16 is the actual output voltage. Show the transition of

  As shown in FIG. 5, after time t1 when the vehicle starts, even if the charging rate SOC falls below the target charging rate SOC *, the generation instruction voltage V * rises because it is in the above-mentioned dead zone or weak zone. The charging rate SOC is further reduced. Then, the power generation instruction voltage V * rises at time t2, and the charging current of the battery 30 rapidly increases. Therefore, in the regenerative control after time t3, the charge amount of the battery 30 decreases due to the influence of charge polarization. Similarly, since the charging current of the battery 30 rapidly increases at time t6, the charge amount of the battery 30 decreases due to the influence of charging polarization in regeneration control after time t7.

  Incidentally, the amount of regeneration when the lower limit guard value VthL is fixed is shown in FIG. The horizontal axis in FIG. 6 is the value of the fixed lower limit guard value VthL, and the vertical axis is the amount of regeneration in the regeneration control in that case. As shown in FIG. 6, by fixing the lower limit guard value VthL to the optimum value (12.4 V in the figure), it is possible to increase the amount of power generated by the alternator 20 and charged in the battery 30 during regeneration control. However, in this case, when the traveling pattern changes, the optimum lower limit guard value VthL also changes, so it is difficult to match the optimum value as the lower limit guard value VthL.

<Correspondence relationship>
Correspondence between the matters in the above-mentioned embodiment and the matters described in the above-mentioned "means for solving the problem" is as follows. The feedback processing corresponds to the processing of S14 and S16, the lower limit guard value setting processing corresponds to the processing of S18, the guard processing corresponds to the processing of S20 and S22, and the operation processing corresponds to the processing of S24 .

<Other Embodiments>
In addition, you may change at least one of each matter of the said embodiment as follows.
In the above embodiment, the feedback manipulated variable for feedback control of the charging rate SOC to the target charging rate SOC * is the output value of the integral element, but the present invention is not limited to this. For example, it may be the sum of the output value of the proportional element and the output value of the integral element.

  -In the above embodiment, while the lower limit guard process based on the lower limit guard value VthL of the power generation instruction voltage V * calculated in the process of S16 is described, the upper limit guard value is not particularly described, but the upper limit guard process by the upper limit guard value It may be executed. However, it is desirable that the upper limit guard value here be smaller than the regeneration instruction voltage VH.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 12 ... Crankshaft, 20 ... Alternator, 22 ... Rotational axis, 30 ... Battery, 40 ... Control apparatus, 42 ... CPU, 44 ... ROM, 46 ... Voltage sensor, 48 ... Current sensor.

Claims (1)

To control a generator that converts rotational power of a crankshaft of an internal combustion engine into electric power and applies an output voltage to a battery
Feedback processing for setting an output voltage of the generator as an operation amount for feedback control of a charging rate of the battery to a target charging rate;
Lower limit guard value setting processing for setting the lower limit guard value of the output voltage;
Guard processing for limiting an output voltage set by the feedback processing to the lower limit guard value or more;
Performing an operation process of operating the generator such that the output voltage subjected to the guard process is obtained;
The control device for a generator, wherein the lower limit guard value setting process is a process of setting the lower limit guard value to a smaller value as the charging rate is larger.