JP2006347283A - Controller for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain optimal power generation control by giving priority to an operation region where the efficiency of a power unit matched with the thermal efficiency of an engine and the efficiency of a motor is sharply increased. <P>SOLUTION: When an XGREQ=1 power generation request is made, power generation torque GENETRQ to maximize an efficiency index is calculated (S2), and lower limit-specified with a power generation torque lower limit value GENEMIN (S3). Then, when power generation is not started (S8, XGENE=0), a real remaining capacity SOC is compared with a power generation start remaining capacity STSOC to determine the validity/invalidity of power generation (S9), and when SCO≤STSOC is satisfied, power generation by the power generation torque GENETRQ is performed (S10), and when SOC>STSOC is satisfied, power generation is not performed. Thus, it is possible to conduct the optimal power generation control by giving priority to an operation region where the efficiency of a power unit matched with the thermal efficiency of an engine and the efficiency of a motor is largely improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hybrid vehicle control device including an engine and a motor coupled to the engine.

  In recent years, in vehicles such as automobiles, an engine that uses gasoline or other fuel as a power source is used with a motor that generates driving force by electric power from a battery for the purpose of promoting low pollution and resource saving. In addition, hybrid vehicles are being developed that use both an engine and a motor.

  Among such hybrid vehicles, in particular, in a parallel hybrid vehicle in which both the engine and the motor can be used as a travel drive source, the driving torque in the region where the engine efficiency is low can be supplemented by the assist torque of the motor. This can lead to improved fuel economy. However, in parallel hybrid vehicles, charging the battery that supplies power to the motor must also be performed during driving other than assist, and if power generation is not properly controlled, fuel consumption is adversely affected. There is.

Accordingly, various proposals have been made regarding power generation control in such a hybrid vehicle. For example, Patent Document 1 discloses that vehicle speed, target driving force, and target generated power can be achieved with minimum fuel consumption. A technique for calculating a target engine speed and determining an optimum engine operating point is disclosed. Further, in Patent Document 2, the sum of the required power of the drive shaft and the battery charging power is set as the engine target power, and when the engine target power is less than a predetermined lower limit value, the battery charging power is changed to deteriorate the engine efficiency. A technique for preventing operation in the output range is disclosed.
JP 2000-236601 A JP 2004-144041 A

  However, when power generation is necessary, it is necessary to consider the efficiency of the power unit that combines the thermal efficiency of the engine and the efficiency of the motor. It is necessary to consider the change in efficiency of the power unit. In Patent Document 1 and Patent Document 2 described above, these points are not considered, and it is not necessarily said that optimal power generation control is realized.

  The present invention has been made in view of the above circumstances, and controls a hybrid vehicle capable of performing optimal power generation control by giving priority to an operation region in which the efficiency of a power unit that combines the thermal efficiency of an engine and the efficiency of a motor is greatly improved. The object is to provide a device.

  In order to achieve the above object, a control apparatus for a hybrid vehicle according to the present invention travels by a driving force from a power unit including an engine and a motor connected to the engine, and drives the motor by the engine. In a control apparatus for a hybrid vehicle that charges an electric storage device that supplies electric power to a motor, based on an electric power generation torque calculating means for calculating electric power generation torque for charging the electric storage device for each operation region, and a remaining capacity of the electric storage device And power generation determining means for determining whether or not power generation is possible for each operation region.

  At that time, it is desirable to calculate the power generation torque so that the efficiency of the power unit that combines the thermal efficiency of the engine and the efficiency of the motor is optimal for each operation region in which the engine speed and the required engine drive torque are parameters. . The power generation torque with the best power unit efficiency can be calculated based on an efficiency index derived from the amount of energy generated by the power unit and the amount of energy generated by the fuel. The power generation torque is desirably a value equal to or greater than the power generation torque lower limit set based on the engine speed and the remaining capacity of the power storage device.

  Whether or not power generation is possible is determined by setting the remaining power generation start capacity based on the correlation between the improvement rate of the efficiency index derived from the amount of energy generated by the power unit and the amount of energy generated by the fuel. It is desirable to determine the remaining capacity by comparing each operation region using the engine speed and the required engine drive torque as parameters. It is desirable to correct the power generation start remaining capacity based on the temperature of the power storage device.

  The control apparatus for a hybrid vehicle according to the present invention can perform optimal power generation control with priority given to an operation region in which the efficiency of the power unit that combines the engine thermal efficiency and the motor efficiency is greatly improved.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 relate to an embodiment of the present invention, FIG. 1 is a system configuration diagram of a hybrid vehicle, FIG. 2 is a flowchart of a power generation control routine, and FIG. 3 shows a relationship between required engine drive torque and power generation torque. FIG. 4 is an explanatory diagram showing the relationship between the remaining capacity, the engine speed, and the power generation torque lower limit value, and FIG. 5 is an explanatory diagram showing the relationship between the remaining power generation start capacity, the engine speed, and the necessary engine driving torque. 6 is an explanatory diagram showing the relationship between the battery temperature and the power generation start remaining capacity temperature correction value.

  FIG. 1 shows a system configuration of a hybrid (HEV) vehicle. In this embodiment, a motor 2 for generating electric power and driving assist force is directly or via a power transmission mechanism such as a gear on an output shaft of an engine 1. 2 shows an example of a system configuration of parallel hybrid vehicles connected together. In this parallel hybrid vehicle, the driving force of the power unit including the engine 1 and the motor 2 is input to the automatic transmission 3 and is output from the automatic transmission 3 to the driving wheels (not shown) via the gear 4 and the final gear 5.

  In addition, an inverter 6 is connected to the motor 2, and the inverter 6 converts DC power from a battery 7 as an electricity storage device that constitutes a main power source of the vehicle into AC power, and drives the motor 2. The battery 7 is configured by connecting a plurality of battery packs in which a plurality of cells are sealed in series, for example, and supplies power to the motor 2 via the inverter 6, and the motor 1 is driven as a generator by the engine 1. When this occurs, AC power generated by the motor 2 is converted to DC power by the inverter 6 and the battery 7 is charged.

  The engine 1, the motor 2, the battery 7, and the automatic transmission 3 are respectively an engine control unit (engine ECU) 10, a motor control unit (motor ECU) 20, a battery management unit (battery ECU) 30, a transmission control unit (transmission ECU). ) 40, and each ECU 10, 20, 30, 40 is connected to a central hybrid control unit (hybrid ECU) 50 that controls the entire system. Each of the ECUs 10, 20, 30, 40 including the hybrid ECU 50 is configured to include various interfaces, peripheral circuits, and the like with a microcomputer at the center. For example, bidirectional communication is performed via a communication line such as a CAN (Controller Area Network). They are connected to each other and communicate control information and sensing information related to the operation state of the controlled object to each other.

  When the functions of the ECUs 10, 20, 30, 40 are outlined, the engine ECU 10 receives a control command from the hybrid ECU 50, and based on signals from sensors provided in the engine 1, the throttle opening, ignition timing, fuel Parameters such as the injection amount are calculated. Then, the actuators are driven by the control signals of these parameters, and the operating state of the engine 1 is controlled so that the output of the engine 1 matches the control command value.

  The motor ECU 20 receives a control command from the hybrid ECU 50 and controls the motor 2 via the inverter 6. Based on information such as the rotation speed, voltage, and current of the motor 2, the motor ECU 20 sends the current command and voltage to the inverter 6. A command is output and the motor 2 is controlled so that the output of the motor 2 matches the control command value.

  The battery ECU 30 determines the state of the battery according to the remaining capacity indicated by the state of charge (SOC) of the battery 7, the input / output possible power amount indicated by the maximum input / output power in the battery 7, the degree of deterioration of the battery 7, etc. It manages the grasping, controlling the cooling and charging of the battery 7 after grasping the battery state, detecting the abnormality, the protection operation at the time of detecting the abnormality, and the like.

  The transmission ECU 40 receives the control command from the hybrid ECU 50, determines the gear position of the automatic transmission 3, and switches to an appropriate gear position according to the driving state. The gear position of the automatic transmission 3 is determined according to a shift diagram set according to the accelerator opening degree ACCRT and the vehicle speed VSP, for example.

  The hybrid ECU 50 that controls the entire HEV system is requested by the driver based on the accelerator opening and the engine speed (motor speed) detected by an accelerator position sensor (APS) 8 that detects the amount of depression of an accelerator pedal (not shown). The driving force to be calculated is calculated as a power unit required torque for the power unit including the engine 1 and the motor 2, and the power unit required torque is appropriately distributed to the engine 1 and the motor 2 to output control commands to the engine ECU 10 and the motor ECU 20.

  Further, when there is a power generation request, that is, the remaining capacity SOC of the battery 7 decreases, the hybrid ECU 50 drives the motor 2 as a generator using the output of the engine 1 and charges the battery 7 via the inverter 6. In this case, the efficiency of the power unit including the engine 1 and the motor 2 is optimized based on the engine speed NE, the engine driving torque (required engine driving torque) DTRQ required for traveling, the remaining capacity SOC of the battery 7, and the like. Power generation control.

  In the present embodiment, the hybrid ECU 50 determines whether or not power generation is possible based on the remaining capacity of the battery 7 for each operation region using the engine speed NE and the required engine drive torque DTRQ as parameters by the function as the power generation possibility determination means. Then, power generation control is performed so that the thermal efficiency of the engine and the efficiency of the motor become high efficiency with the power generation torque calculated by the function as the power generation torque calculation means.

In this power generation control, an efficiency index ηG calculated by the following equation (1) is introduced, and a torque (power generation torque) GENETRQ required for power generation is determined so that the value of the efficiency index ηG is maximized.
ηG = (DTRQ × NE + PWG) / (GF × QF) (1)
However, PWG: Generated power
GF: Fuel amount required to generate (DTRQ + GENETRQ)
QF: Fuel calorific value

  The efficiency index ηG represents the amount of energy of the power unit that can be generated by the amount of fuel per unit, and when this value is maximized, the power generation energy to the battery 7 can be obtained with the least amount of fuel. Efficient power generation is possible. Therefore, in order to improve the fuel consumption, it is necessary to generate power in a region where the improvement rate from the case of no power generation of the efficiency index ηG is large.

  For this reason, the hybrid ECU 50 considers that the urgency of power generation is low when the remaining capacity SOC of the battery 7 is large even when there is a power generation request, and performs power generation only in the operation region where the improvement rate of the efficiency index ηG is large. . Then, as the remaining capacity SOC decreases and the urgency with respect to power generation increases, the power generation area is expanded while taking into account the efficiency improvement rate of the power unit.

  Specifically, the above power generation control is executed by a power generation control routine shown in the flowchart of FIG. Next, power generation control will be described with reference to the flowchart of FIG.

  The power generation control routine of FIG. 2 is a program process executed at predetermined time intervals or at predetermined intervals. First, in a first step S1, a power generation request flag XGREQ from the battery ECU 30 is referred to. As a result, if XGREQ = 0 and there is no power generation request, the routine exits without performing power generation control substantially. If XGREQ = 1 and there is a power generation request, the process proceeds to step S2.

  In step S2, a power generation torque GENETRQ that maximizes the efficiency index ηG is calculated. Specifically, the power generation torque GENETRQ is obtained by conducting experiments or simulations in advance on the relationship of the expression (1) in consideration of the characteristics of the engine 1 and the motor 2, and setting the engine speed NE and the required engine drive torque DTRQ as parameters. Is stored in a table and determined by referring to this table.

  FIG. 3 shows the relationship between the required engine driving torque DTRQ and the power generation torque GENETRQ under the same engine speed NE, and the engine can be maintained with high efficiency while the required engine driving torque DTRQ satisfies the required driving force. Until the set value is reached, the power generation torque GENETRQ is kept constant. When the required engine drive torque DTRQ increases beyond the set value, the required drive force is given priority and the power generation torque GENETRQ is reduced.

  Next, the process proceeds to step S3, where a power generation torque lower limit value GENEMIN is calculated by referring to a table or the like based on the engine speed NE and the actual remaining capacity SOC from the battery ECU 30. The power generation torque lower limit value GENEMIN is the minimum power generation torque for maintaining the battery performance. As shown in FIG. 4, when the engine speed NE is the same, the lower the remaining capacity SOC, the larger the power generation torque lower limit value GENEMIN. When the actual remaining capacity SOC is the same, the power generation torque lower limit value GENEMIN is relatively decreased as the engine speed NE is higher.

  In step S4 following step S3, the power generation torque GENETRQ is compared with the power generation torque lower limit value GENEMIN. When GENETRRQ ≧ GENEMIN and the calculated power generation torque GENETRQ is equal to or greater than the power generation torque lower limit value GENEMIN, the process jumps to step S6, where GENETRQ <GENEMIN, and the calculated power generation torque GENETRQ is greater than the power generation torque lower limit value GENEMIN. If it is smaller, the power generation torque lower limit value GENEMIN is reset as the power generation torque GENETRQ in step S5 (GENETRQ = GENEMIN), and the process proceeds to step S6.

  In step S6, a power generation start remaining capacity STSOC for determining whether or not to start power generation is calculated. The power generation start remaining capacity STSOC is calculated by first obtaining a basic value (basic value of power generation start remaining capacity) STSOCB of a remaining capacity capable of starting power generation with high efficiency, and correcting the temperature of the power generation start remaining capacity basic value STSOCB. To do.

  The power generation start remaining capacity basic value STSOCB is a table created based on the correlation between the power generation start remaining capacity basic value STSOCB and the improvement rate of the efficiency index ηG for each operation region based on the engine speed NE and the required engine drive torque DTRQ. Seek and ask. As shown in FIG. 5, when the power generation start remaining capacity basic value STSOCB is small, high-efficiency power generation is possible in a wide operating range of the engine speed NE and the required engine drive torque DTRQ, and the power generation start remaining capacity basic value When STSOCB increases, high-efficiency power generation is possible only in a part of the region where the engine speed NE is in the middle rotation range and the required engine drive torque DTRQ is small.

  Furthermore, the power generation start remaining capacity basic value STSOCB is temperature-corrected by a power generation start remaining capacity temperature correction value KTEMPB set based on the temperature TEMPB of the battery 7, and the temperature corrected power generation start remaining capacity basic value STSOCB actually generates power. It is calculated as the power generation start remaining capacity STSOC for determining whether or not to start.

  As shown in FIG. 6, the power generation start remaining capacity temperature correction value KTEMPB corrects the influence of the remaining capacity that decreases in the low temperature range, and the value of the power generation start remaining capacity temperature correction value KTEMPB decreases as the temperature decreases. It is increased in the range of> 1, and above the reference temperature, KTEMPB = 1 and substantially no correction.

  After calculating the power generation start remaining capacity STSOC, the process proceeds to step S7 to calculate the power generation end remaining capacity FNSOC for determining the end of power generation. In this embodiment, the power generation end remaining capacity FNSOC is calculated as a value slightly higher than the power generation start remaining capacity STSOC by adding a set value to the power generation start remaining capacity STSOC.

  Next, the process proceeds to step S8, where a power generation execution flag XGENE indicating that power generation is being executed is referred to and it is checked whether or not power generation is currently being performed. As a result, if XGENE = 0 and power generation is not started, the process proceeds from step S8 to step S9, and the current actual remaining capacity SOC and the power generation start remaining capacity STSOC are compared to determine whether power generation is possible. If SOC ≦ STSOC, the process proceeds from step S9 to step S10 to generate power with the power generation torque GENETRQ, and the power generation execution flag XGENE is set to 1 (XGENE = 1). In step S9, if SOC> STSOC, it is determined that the urgency level of power generation is low, the routine is exited from step S9, and power generation is not performed.

  On the other hand, if XGENE = 1 in step S8, that is, if power generation is in progress, the process proceeds from step S8 to step S11, where the actual remaining capacity SOC and the power generation end remaining capacity FNSOC are compared. If SOC ≦ FNSOC, the routine exits from step S11 while continuing power generation. If SOC> FNSOC, the process proceeds from step S11 to step S12 to end power generation, clear the power generation execution flag XGENE (XGENE = 0) Exit the routine.

  As described above, in the present embodiment, the optimal power generation torque is set for each operation region, and power generation is performed with priority given to the operation region in which the power unit composed of the engine and the motor is highly efficient, and the efficiency improvement rate of the power unit The power generation area will be expanded while taking this into consideration. Thereby, optimal power generation control can be performed, and traveling with stable fuel consumption and charging of the battery (power storage device) can be performed.

  In the above embodiment, the parallel hybrid vehicle has been described. However, the present invention is not limited to the parallel hybrid vehicle, but can be applied to a parallel traveling mode in a series / parallel hybrid vehicle.

Hybrid vehicle system configuration diagram Flow chart of power generation control routine Explanatory drawing showing the relationship between required engine drive torque and power generation torque Explanatory diagram showing the relationship between the remaining capacity, engine speed and power generation torque lower limit Explanatory drawing showing the relationship among the remaining power generation start capacity, engine speed and required engine drive torque Explanatory drawing which shows the relationship between battery temperature and power generation start remaining capacity temperature correction value

Explanation of symbols

1 Engine 2 Motor 7 Battery (power storage device)
50 Hybrid control unit NE Engine speed DTRQ Required engine drive torque GENETRQ Power generation torque GENEMIN Power generation torque lower limit value SOC Remaining capacity STSOC Power generation remaining capacity ηG Efficiency index

Claims (6)

In a control apparatus for a hybrid vehicle that travels by a driving force from a power unit including an engine and a motor connected to the engine, drives the motor by the engine, and charges an electric storage device that supplies electric power to the motor. ,
Power generation torque calculating means for calculating the power generation torque for charging the power storage device for each operation region;
A control device for a hybrid vehicle, comprising: a power generation determining unit that determines whether power generation is possible for each operation region based on the remaining capacity of the power storage device. The power generation torque calculating means includes
The power generation torque at which the efficiency of the power unit that combines the thermal efficiency of the engine and the efficiency of the motor is calculated for each operation region having the engine speed and the required engine drive torque as parameters. Item 2. A hybrid vehicle control device according to Item 1. The power generation torque calculating means includes
3. The control apparatus for a hybrid vehicle according to claim 2, wherein the power generation torque is calculated based on an efficiency index derived from the amount of energy generated by the power unit and the amount of energy generated by fuel. The power generation torque calculating means includes
4. The hybrid vehicle according to claim 1, wherein the power generation torque is set to a value equal to or greater than a power generation torque lower limit value set based on an engine speed and a remaining capacity of the power storage device. Control device. The power generation determining means is
Correlation between the remaining capacity of the electricity storage device and the improvement rate of the efficiency index derived from the amount of energy generated by the power unit and the amount of energy generated by the fuel for each operation region in which the engine speed and the required engine driving torque are parameters. 5. The hybrid vehicle control device according to claim 1, wherein whether or not power generation is possible is determined in comparison with a remaining power generation start remaining capacity set based on the above. The power generation determining means is
The hybrid vehicle control device according to claim 5, wherein the remaining power generation start remaining capacity is corrected by a temperature of the power storage device.

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