JP5924135B2 - Current integrating device - Google Patents

Description

  The present invention relates to a current integrating device that calculates a charging / discharging current of a vehicle battery based on a current sensor.

  In general, the state of charge of the battery (battery SOC) is calculated using the integrated value of the charge / discharge current detected by the current sensor. For example, in Patent Document 1, in a vehicle that includes an electric motor having both an alternator function and a motor function and starts the engine using the electric motor when returning from an idle stop, based on the battery SOC calculated using the integrated value of the charge / discharge current. It is determined whether or not the idle stop control can be executed.

JP 2003-269213 A

  By the way, the charge / discharge current of the battery is about several tens of amperes when the vehicle is traveling, but increases to several hundred amperes when the motor function of the electric motor is used. Therefore, in a vehicle that uses the motor function of an electric motor when returning from an idle stop, when trying to calculate the integrated value of the charge / discharge current, a current sensor with a wide measurable range that can be detected up to the current value when the electric motor is operating is required. Become.

  However, in the current sensor having a wide measurable range as described above, the resolution for a small current value with respect to the entire measurable range, such as the current value when the motor is not operated, is lowered, and the detection accuracy is lowered. On the other hand, the use of a current sensor that includes the current value when the motor is operated within the measurable range and has a high resolution for the current value fluctuation range when the vehicle is running increases the cost. Patent Document 1 does not describe anything about such detection accuracy and cost increase problems. Note that the above-described problem is not limited to the return from the idle stop, but may occur if the motor function of the electric motor is used.

  Therefore, an object of the present invention is to provide a current integrating device that can accurately calculate an integrated current value and avoid an increase in cost in a vehicle including an electric motor that can also be used as a motor.

  A current integrating device of the present invention is mechanically coupled to a drive shaft of an internal combustion engine, and operates to torque assist the internal combustion engine, a first battery that supplies electric power to the motor, and an electric motor during torque assist execution. An integrated current value is calculated in a vehicle including a second battery that supplies power to an electric load other than the above. In addition, the vehicle includes a first battery and a second battery that are connected in parallel when torque assist is not executed, and a relay that releases the parallel connection when torque assist is executed, and an electric motor that is gradually released after the parallel connection is released when torque assist is executed. Motor control means for increasing the generated torque. The current integrating device includes current detecting means for detecting the charge / discharge current of the first battery, and current integrated value calculating means for calculating the current integrated value of the first battery by integrating the detected values of the current detecting means. . Further, the current integrating device stores in advance a current value that exceeds the measurable range of the current detection means that flows during execution of torque assist as a correction current value, and when executing torque assist, the current integration device uses the current value for correction as a correction current value. Current value correcting means for correcting the integrated current value based on the current value is provided.

  According to the present invention, when the torque assist is executed, the current integrated value is corrected based on the correction current value. Therefore, even when the current detection unit that cannot detect a large current at the time of torque assist is used, The integrated current value can be calculated with high accuracy. As a result, it is possible to obtain the effect of reducing the cost of the current detecting means and improving the calculation accuracy of the battery current integrated value.

FIG. 1 is a configuration diagram of a system according to an embodiment of the present invention. FIG. 2 is a flowchart of a routine for judging permission / inhibition of execution of torque assist. FIG. 3 is a time chart of assist torque generated by the electric motor. FIG. 4 is a flowchart of a current integrated value calculation routine. FIG. 5 is another example of a flowchart of the current integrated value calculation routine.

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

  FIG. 1 is a configuration diagram of an electrical system for a vehicle according to an embodiment of the present invention.

  This system mainly includes a main battery 3 that supplies power to the electric motor 1, the starter 2, and the first electric load group 9, a sub battery 4 that mainly supplies power to the second electric load group 10, A controller (ECM) 6 for controlling electrical components is provided.

  The rotating shaft of the electric motor 1 is mechanically connected to a crankshaft of an internal combustion engine (not shown) using a belt or the like. Further, the electric motor 1 includes an inverter, and has a motor function that is driven by electric power supplied from the main battery 3 and a power generation function that is driven by a driving force of an internal combustion engine (not shown) to generate electric power. The ECM 6 switches between the motor function and the power generation function. The motor function is used mainly when returning from the idle stop and when executing torque assist during acceleration. Torque assist refers to using the output of the electric motor 1 as an auxiliary to the output of the internal combustion engine when a large output is required, such as during acceleration or traveling on an uphill road. The torque assist control will be described later.

  The starter 2 includes a pinion gear that moves forward and backward in the same manner as a general starter for starting, and during operation, the pinion gear engages with a gear provided on the outer periphery of a drive plate attached to a crankshaft base end portion to perform cranking. Do.

  The ECM 6 reads a detection signal of a sensor that detects an operating state of the accelerator opening sensor 11 and the like, and based on these signals, controls the general fuel injection amount, ignition timing, etc., and controls the relay 5 and torque assist control described later. Etc.

  The ECM 6 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). It is also possible to configure the ECM 6 with a plurality of microcomputers.

  The main battery 3 mainly supplies power to the first electric load group 9. The first electric load group 3 is an electric product group that can tolerate an instantaneous voltage drop called so-called instantaneous drop during torque assist. In addition to the ECM 6, the starter 2, and the inverter of the electric motor 1, for example, a headlight and a wiper are included.

  The sub battery 4 supplies power to the second electric load group 10. The second electrical load group 10 is an electrical component group that cannot tolerate a sag during torque assist, and includes, for example, each meter, a navigation system, and the like.

  Both the main battery 3 and the sub battery 4 are charged with the electric power generated by the electric motor 1. However, a relay 5 is interposed between the sub battery 4 and the electric motor 1. The relay 5 includes two relays, a relay 5A and a relay 5B, and is a so-called redundant system. Switching between the relay 5A and the relay 5B is performed by the ECM 6. When the relay 5 is turned on, the main battery 3 and the sub battery 4 are connected in parallel, and power can be supplied from the main battery 3 to the second electric load group 10. The switching of the relay 5 will be described later.

  The charge / discharge currents of the main battery 3 and the sub-battery 4 are detected by current sensors 7 and 8, respectively, and read into the ECM 6. The ECM 6 calculates a current integrated value from the detected value of the charge / discharge current, and calculates the battery SOC of the main battery 3 and the sub battery 4 based on the current integrated value.

  The current sensors 7 and 8 have a measurable range set based on the magnitude of charge / discharge current during running (hereinafter referred to as normal running) except when torque assist is executed and when the internal combustion engine is started. That is, a measurable range is used in which the maximum current value that can be taken during normal running is within the measurable range, and the maximum current value that can be taken during normal running is near the upper limit of the measurable range. The current value that can be taken during normal driving is about several tens of amperes, while the current value at the time of torque assist execution or when the internal combustion engine is started is about several hundred amperes. Therefore, when the measurable range of the current sensors 7 and 8 is set as described above, the current value at the time of executing the torque assist or starting the internal combustion engine is outside the measurable range. However, the current integrated value calculation including the time of torque assist can be calculated with high accuracy even in the measurable range as described above by calculating the current integrated value described later.

  Here, switching of the motor function and the power generation function of the electric motor 1 and switching of the relay 5 will be described for each operation scene of (A)-(I).

  (A) In the system stop state, for example, from the end of vehicle operation to the next operation, both the relay 5A and the relay 5B are turned off.

  (B) When the internal combustion engine is started by the driver's operation, power is supplied from the main battery 3 to the starter 2 while both the relay 5A and the relay 5B are OFF, and the starter 2 starts the internal combustion engine. After the internal combustion engine is completely exploded, the electric motor 1 generates power and turns on either the relay 5A or the relay 5B. Here, the target power generation voltage of the electric motor 1 is 14V, and the main battery 3 and the sub battery 4 are 14V in a fully charged state. Thereby, the charging of the main battery 3 and the sub battery 4 is completed by the electric power generated by the electric motor 1.

  (C) At the time of steady running or acceleration that does not involve torque assist, the state in which either the relay 5A or the relay 5B is turned on is maintained as in the start. And the electric motor 1 is made into a non-power-generation state by reducing the target electric power generation voltage of the electric motor 1 to about 12V, for example. Thereby, the load of the internal combustion engine can be reduced, and the fuel efficiency can be improved.

  (D) At the time of deceleration, the state in which either relay 5A or relay 5B is turned on is maintained as in the start. The electric motor 1 performs regenerative power generation with a target power generation voltage of 14 V and charges the main battery 3 and the sub-battery 4.

  (E) When performing a so-called idle stop during vehicle operation, both the relay 5A and the relay 5B are turned OFF, and the system is stopped.

  (F) When returning from idle stop, both relay 5A and relay 5B remain OFF. Electric power is supplied from the main battery 3 to the electric motor 1, and the electric motor 1 functions as a motor to start the internal combustion engine. That is, when returning from the idle stop, the internal combustion engine is restarted by the motor function of the electric motor 1 without using the starter 2.

  (G) After the complete explosion at the time of restart, the relay 5 opposite to that during the operation before the idle stop is turned on to switch the electric motor 1 to the power generation function.

  (H) When executing the torque assist, both the relay 5A and the relay 5B are turned OFF, and power is supplied from the main battery 3 to the electric motor 1. By turning off both relay 5A and relay 5B, sub battery 4 and electric motor 1 are electrically disconnected. As a result, stable power supply from the sub-battery 4 to the second electric load group 10 can be performed even during execution of torque assist, and an instantaneous drop of the second electric load group 10 can be prevented.

  In this embodiment, for simplicity, torque assist is started when the change rate of the accelerator opening becomes equal to or higher than a predetermined value, and torque assist is started until the accelerator opening decreases or when a predetermined time elapses from the start of torque assist. It shall end.

  (I) After the torque assist is completed, the relay 5 opposite to that before the torque assist is performed is turned on.

  Next, a torque assist control routine will be described.

  FIG. 2 is a flowchart showing an example of a determination routine executed by the ECM 6 as to whether or not to execute torque assist. This routine is basically repeatedly executed at intervals of, for example, several milliseconds. However, when executing the torque assist in step S140 described later, this routine is stopped until the torque assist is completed.

  In step S100, the ECM 6 reads the accelerator opening APO detected by the accelerator opening sensor 11.

  In step S110, the ECM 6 determines whether or not the accelerator opening change amount ΔAPO calculated based on the accelerator opening APO is equal to or greater than a preset threshold value. As the accelerator opening change ΔAPO, for example, the difference between the previous value and the current value of the accelerator opening APO may be calculated, or the change amount within the latest predetermined time may be calculated. In this determination, the magnitude of the accelerator opening change ΔAPO is regarded as the magnitude of the driver's acceleration request, and it is determined whether torque assist is necessary to satisfy the driver's acceleration request. Therefore, the specific magnitude of the threshold differs for each vehicle model to which this control is applied.

  As a result of the determination, if the accelerator opening change amount ΔAPO is equal to or larger than the threshold value, the process of step S130 is executed, and if it is smaller than the threshold value, this routine is terminated as it is.

  In step S130, the ECM 6 determines whether or not the SOC of the main battery 3 is equal to or greater than a preset threshold value. The SOC of the main battery 3 is calculated by the ECM 6 based on the integrated value of the charge / discharge current detected by the current sensor 7 as described above. The threshold value is a value that satisfies the electric power necessary for driving the electric motor 1 for torque assist and the electric power necessary for operating the first electric load group 9 during execution of torque assist. Set in advance.

  As a result of the determination, if the SOC of the main battery 3 is equal to or greater than the threshold value, it means that torque assist can be executed, so the torque assist command is turned on and the process of step S140 is executed. On the other hand, if the SOC of the main battery 3 is lower than the threshold value, it means that torque assist cannot be executed. Therefore, the torque assist command is turned off, and this routine is terminated as it is.

  In step S140, the ECM 6 executes torque assist.

  FIG. 3 is a time chart of torque generated by the electric motor 1 when torque assist is executed (hereinafter referred to as assist torque). The torque assist of the present embodiment is to generate assist torque in a certain pattern when the torque assist command is turned on. That is, when the torque assist command is turned on at timing T1, the electric motor 1 gradually increases the assist torque to the torque Q, and when the torque Q reaches the torque Q, maintains the assist torque for a certain time, and then gradually decreases the assist torque. Here, the increase / decrease of the assist torque is not stepwise but is performed gradually in order to suppress a sudden change in tension of a belt or the like connecting the electric motor 1 and a drive shaft of an internal combustion engine (not shown).

  The period from timing T1 to timing T2 is about several seconds. Torque Q differs for each vehicle model to which this control is applied. The torque assist according to the present embodiment is, as a general rule, executed once once started as described above. However, it is forcibly terminated when a sudden voltage drop occurs for some reason. .

  Next, calculation of the current integrated value will be described.

  FIG. 4 is a flowchart of a current integrated value calculation routine executed by the ECM 6. This routine is repeatedly executed at intervals of, for example, several milliseconds.

  In step S200, the ECM 6 determines whether torque assist is currently being executed. If torque assist is being executed, the process of step S210 is executed; otherwise, the process of step S220 is executed.

In step S210, the ECM 6 calculates the current integrated value of the main battery 3 by the following equation (1). In Equation (1) and Equation (2) described later, I is the battery current value (current sensor detection value), I _sum is the battery current integrated value, I _{sum [old]} is the previous value of the battery current integrated value, I _ta is a correction value for torque assist.

I _sum = I _{sum [old]} + I + I _ta (1)
That is, the current integrated value of the main battery 3 during execution of torque assist is calculated as the sum of the previous value, the detected value of the current sensor 7 and the correction value for torque assist. Then, the battery current integrated value I _sum calculated this time is stored, and this is used as I _{sum [old] in} the next calculation.

The torque assist correction value _Ita is a current value that exceeds the measurable range of the current sensor 7 in the discharge current corresponding to the assist torque change pattern of FIG. 3 described above. That is, the discharge current _Ita having a magnitude corresponding to the magnitude of the assist torque at that time is added for each calculation cycle.

  Thereby, even if the magnitude of the discharge current exceeds the measurable range of the current sensor 7 by executing the torque assist, the current integrated value can be calculated with high accuracy.

  In step S220, the ECM 6 calculates the current integrated value of the main battery 3 by the following equation (2).

I _sum = I _{sum [old]} + I (2)
That is, step S220 is executed during normal driving, and the discharge current of the main battery 3 is within the measurable range of the current sensor 7, so that the current value is set to the previous value as in the general current integrated value calculation. Is added.

  In addition, instead of the method of adding the correction value for torque assist at each calculation cycle as in step S210 in FIG. 4, the current integrated value may be corrected collectively after the torque assist is completed.

  FIG. 5 is a flowchart showing a control routine for correcting the integrated current value after the end of torque assist.

  In step S300, the ECM 6 calculates the current integrated value of the main battery 3 by the equation (2) as in step S220 of FIG.

  In step S310, the ECM 6 determines whether torque assist is currently being executed. If torque assist is being executed, the torque assist flag F is set to 1 in step S320 and the routine is terminated. If torque assist is not being executed, the process of step S330 is executed.

  In step S330, the ECM 6 determines whether the torque assist flag F is 1 or not. If F = 1, the process of step S340 is executed, and if F = 0, this routine ends.

In step S340, the ECM 6 adds the current integration correction value to the current integration value I _sum . The current integration correction value is an integrated value of the discharge current that exceeds the measurable range of the current sensor 7 from the start to the end of torque assist, that is, an integrated value of Ita in the equation (1), and is obtained and set in advance through experiments or the like. To do.

  In step S350, the ECM 6 returns the torque assist flag F to zero and ends this routine.

  As described above, even if the discharge current integrated value in one torque assist is added after the torque assist is completed, the current integrated value can be calculated with high accuracy as in the control routine of FIG.

  According to this embodiment described above, the following effects can be obtained.

  The ECM 6 stores in advance a current value that exceeds the measurable range of the current sensor 7 that flows during execution of torque assist as a correction current value, and when executing torque assist, the ECM 6 is based on the correction current value. The integrated value of the detection value of the current sensor 7 is corrected. As a result, the current integrated value can be calculated with high accuracy even when the current sensor 7 is used so that the current value when the electric motor 1 is activated is outside the measurable range. The effect of improving the calculation accuracy is obtained.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

DESCRIPTION OF SYMBOLS 1 Electric motor 2 Starter 3 Main battery (1st battery)
4 Sub battery (second battery)
5 relay 6 controller (ECM) (current integrated value calculation means, current value correction means)
7 Current sensor (current detection means)
8 Current sensor 9 First electric load group 10 Second electric load group 11 Accelerator opening sensor

Claims (2)

An electric motor that is mechanically coupled to a drive shaft of the internal combustion engine and operates to assist torque in the internal combustion engine;
A first battery which is a power source for supplying electric power to the electric motor during execution of the torque assist;
A second battery that is a power source for supplying electric power to an electric load other than the electric motor during execution of the torque assist;
A relay that connects the first battery and the second battery in parallel when the torque assist is not executed, and releases the parallel connection when the torque assist is executed;
Electric motor control means for gradually increasing the generated torque of the electric motor after releasing the parallel connection at the time of executing the torque assist;
Current detection means for detecting a charge / discharge current of the first battery;
A current integrating device for calculating a current integrated value in a vehicle comprising:
Current integrated value calculating means for calculating the current integrated value of the first battery by integrating the detected values of the current detecting means;
A current value that exceeds the measurable range of the current detection means that flows during execution of the torque assist is stored in advance as a correction current value, and when the torque assist is executed, the current value is calculated based on the correction current value. Current value correcting means for correcting the current integrated value;
A current integrating device comprising: In the current integrating device according to claim 1,
The current detector is a current integrating device that is a maximum value of the charge / discharge current of the first battery when the torque assist is not executed even when the upper limit of the measurable range is maximum.

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