JP2006341708A - Controller for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform an optimal power generation control in consideration of required electric power and power generation efficiency in an operating range of an entire vehicle. <P>SOLUTION: The required electric power of the entire vehicle is converted into a relation between an engine speed and a power generation torque as production Pb of electricity. The power generation is excluded or the production of electricity is reduced in a region with poor power generation efficiency, such as in a region with a low number of revolutions. Also, the corresponding insufficiency in production of electricity is shifted to a region with a high power generation efficiency and it is considered to be a basic power generation torque Tb of the vehicle. When a remaining capacity SOCN is smaller than a target remaining capacity SOCT, it is slid in a torque axis direction so that an entire basic electric generation torque Tb increases by preset quantity to be a power generation torque indicative value, and when the remaining capacity SOCN is larger than the target remaining capacity SOCT, it is slid in the torque axis direction such that the entire basic electric power generation torque Tb decreases by preset quantity to be the power generation torque indicative value. The optimal power generation control can be achieved and fuel economy can be improved while securing required production of electricity. <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 battery charge control in a parallel hybrid vehicle in which the remaining battery capacity (SOC) is the SOC upper limit value. When performing ping-pong control so as to fall between the SOC lower limit values, two types of control modes, a normal SOC control mode and a traffic jam SOC control mode, are provided. In a traffic jam SOC control mode, normal SOC control is performed. A technique is disclosed in which the SOC upper limit value is set larger than the mode, and the SOC lower limit value is set small, thereby preventing the exhaust gas and fuel consumption from deteriorating in a traffic jam.

Further, in Patent Document 2, as the power storage amount of the power storage device is higher, the target travel efficiency, which is the target value of the travel efficiency during vehicle travel, is set to be smaller, and the balance of the charge / discharge amount in the travel pattern at the cruising speed is set. The target travel efficiency is set so that the change rate of the target travel efficiency with respect to the storage amount near the optimum travel efficiency that can be taken is smaller than the change rate of the target travel efficiency with respect to the storage amount outside the vicinity of the optimal travel efficiency. By calculating the target operating point that is the operating point of the internal combustion engine and the generator that achieves the target traveling efficiency based on the above, and driving and controlling the internal combustion engine and the generator, high-efficiency power generation is realized, and the internal combustion engine or the fuel A technique for effectively reducing the amount of fuel consumed by a battery and the amount of exhaust gas components to be restricted has been disclosed.
JP 2000-134719 A JP 2003-70102 A

  However, in order to optimally control power generation, it is necessary to consider the required power of the entire vehicle that depends on the efficiency of each device operated by power supplied directly or indirectly from the battery. Since the operation region changes during operation, it is necessary to consider the power generation efficiency in each operation region.

  In the above-mentioned Patent Document 1, the efficiency of each device at the time of power generation is not particularly considered, and in the technique of Patent Document 2, when the running state in which the amount of power storage is low and the power generation amount cannot be sufficiently secured continues for a long time. There is a concern about the deterioration of efficiency. In other words, it is difficult to say that the power generation control is optimally realized by the techniques of Patent Document 1 and Patent Document.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for a hybrid vehicle capable of performing optimal power generation control in consideration of necessary power of the entire vehicle and power generation efficiency in an operation region. It is said.

  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 hybrid vehicle control device that charges an electricity storage device that supplies power to a motor, based on the required power of the entire vehicle taking into account the equipment efficiency and the power generation efficiency for each operating region, the basic power generation torque with the engine speed as a parameter And a basic power generation torque setting means for setting the power generation torque instruction value of the power unit by increasing or decreasing the basic power generation torque according to at least a difference between the remaining capacity of the power storage device and a preset target remaining capacity. And an instruction means.

  It is desirable to set the basic power generation torque by decreasing the power generation torque in the engine speed region where the power generation efficiency is low, and increasing the power generation torque in the engine speed region where the power generation efficiency is high.

  In addition to the difference between the remaining capacity of the electricity storage device and the preset target remaining capacity, it is desirable to set the power generation torque instruction value in consideration of the engine efficiency, and the remaining capacity of the electricity storage device is less than or equal to the target remaining capacity. The basic power generation torque is increased by sliding the basic power generation torque so that the basic power generation torque increases uniformly with respect to the engine speed. When the remaining capacity of the electricity storage device exceeds the target remaining capacity, the basic power generation torque It is desirable to slide the basic power generation torque so that the power generation torque instruction value decreases uniformly with respect to the engine speed.

  Furthermore, when the remaining capacity of the power storage device exceeds the upper limit value, it is desirable to immediately stop power generation by the power unit and continue power generation stop until the remaining capacity of the power storage device decreases to the target remaining capacity.

  The hybrid vehicle control device of the present invention can perform optimal power generation control in consideration of the required power of the entire vehicle and the power generation efficiency in the driving region, and can contribute to improvement in fuel consumption.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to an embodiment of the present invention, FIG. 1 is a system configuration diagram of a hybrid vehicle, FIG. 2 is an explanatory diagram in which a power generation amount is converted into a relationship between an engine speed and a power generation torque, and FIG. FIG. 4 is an explanatory view showing a slide of the power generation amount, and FIG. 5 is a flowchart of a power generation control routine.

  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 the 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 a transmission (not shown), and is output from the transmission to driving wheels via a final gear or the like.

  In addition, an inverter 3 is connected to the motor 2, and the inverter 3 converts DC power from a battery 4 as an electricity storage device constituting a main power source of the vehicle into AC power, and drives the motor 2. When electric power is supplied from the battery 4 to the motor 2 via the inverter 3, and the motor 2 is driven as a generator by the engine 1, AC power generated by the motor 2 is converted into DC power by the inverter 3, and the battery 4 Is charged.

  The power unit and inverter 3 described above are controlled by the power unit control unit 10, and the battery 4 is managed and controlled by the power management unit 20. The power unit control unit 10 is connected to a central hybrid control unit 50 that controls the entire HEV system, and is related to the control information and the operation state of the control target via a communication line such as a CAN (Controller Area Network). Sensing information is communicated with each other, and the drive system and power system of the hybrid vehicle are controlled based on a control command from the hybrid control unit 50.

  The power unit control unit 10 is formed by various control functions such as an engine control unit that controls the engine 1 and a motor control unit that controls the motor 2 via the inverter 3. The engine control function receives control commands from the hybrid controller 50, calculates parameters such as throttle opening, ignition timing, fuel injection amount, etc. based on signals from sensors provided in the engine 1, The actuators are driven by the control signal of the parameter, and the operation state of the engine 1 is controlled so that the output of the engine 1 matches the control command value. The motor control function receives a control command from the hybrid control unit 50, outputs a current command or a voltage command to the inverter 3 based on information such as the rotation speed of the motor 2, voltage / current, etc. The motor 2 is controlled so that the output matches the control command value.

  Note that each control function of the power unit control unit 10 is specifically configured as a separate device or a device including a plurality of control functions, with a microcomputer as the center.

  The power management unit 20 includes, for example, a battery 4 configured by connecting a plurality of battery packs in which a plurality of cells are sealed in series, and an arithmetic unit (arithmetic ECU) 5 that performs energy management of the battery 4. Are packaged in one housing. The arithmetic ECU 5 is composed of a microcomputer or the like, and based on parameters such as the terminal voltage V, current I, and battery temperature (cell temperature) T of the battery 4, the remaining capacity SOCN indicated by a state of charge (SOC). Is calculated and transmitted to the hybrid control unit 50.

  The remaining capacity is calculated periodically every time t, and the latest capacity is calculated from the latest terminal voltage V, current I, and battery temperature T using the remaining capacity SOCN (t−1) one calculation period before. The remaining capacity SOCN (t) is calculated.

  In addition to the remaining capacity SOCN of the battery 4, the calculation ECU 5 calculates the input / output possible power amount indicated by the maximum power that can be input / output in the battery 4, the degree of deterioration of the battery 4, etc., and the battery based on these information While controlling the cooling and charging of the battery 4 after grasping the state, the abnormality detection and the protection operation at the time of abnormality detection are managed.

  On the other hand, the hybrid control unit 50 that controls the entire HEV system is similarly configured with a microcomputer at the center, and determines the amount of accelerator pedal depression (accelerator opening) and engine speed (motor speed) detected by the sensor. Based on this, the driving force requested by the driver is calculated as a power unit required torque for the power unit composed of 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 control the power unit controller 10. Is output.

  Further, when there is a power generation request from the power management unit 20, the hybrid control unit 50 reduces the remaining capacity SOCN of the battery 4 and drives the motor 2 as a generator using the output of the engine 1. When the battery 4 is charged via 3, the basic generation torque is set by considering the necessary electric power of the entire vehicle system and the generation efficiency of the operation region by the function as the basic generation torque setting means, and the power generation instruction means With this function, the basic power generation torque is increased / decreased according to the difference between the current remaining capacity and the preset target remaining capacity, and an instruction value for the power generation torque for the power unit is set.

Specifically, a low-voltage electric load that operates via each device that is directly or indirectly supplied with power from the battery 4, such as a control system, a motor 2, an inverter 3, and a DC-DC converter. The power required for the entire vehicle is determined in advance in consideration of the efficiency of each device, etc., and this required power is used as the power generation amount Pb, and the following equation (1) is used for the engine speed N and power generation. It is converted into a relationship with torque (power generation torque) T.
Pb = (2 × π × N / 60) × T (1)

  When the power generation amount Pb is constant, the power generation torque T depends on the output characteristics of the power unit. For example, as shown in FIG. Converted. If the power generation torque T having the characteristics shown in FIG. 2 is applied to the entire operation region as it is, the fuel consumption may be worsened in the operation region where the power generation efficiency is poor.

  Therefore, as shown in FIG. 3, in a region where the power generation efficiency is low, such as in a low rotation speed region, the vehicle is excluded by generating power or reducing the power generation amount and shifting the shortage of the power generation amount to a region where the power generation efficiency is high. Basic power generation torque Tb. The amount of power generation shift is low, for example, by setting a weight corresponding to the power generation efficiency for each region and shifting the power generation torque T from a low efficiency region to a high efficiency region according to this weight. Fuel consumption loss in the area can be minimized.

  Further, the basic power generation torque Tb is varied according to the difference between the preset target remaining capacity SOCT and the current remaining capacity SOCN, and the power generation torque instruction value is set. That is, when the remaining capacity SOCN is smaller than the target remaining capacity SOCT (SOCT-SOCN> 0) in the relationship between the engine speed N and the power generation torque T, the basic power generation torque indicated by the solid line as shown by the broken line in FIG. The power generation torque instruction value is obtained by sliding in the torque axis direction so that the entire Tb is increased by the set amount. Further, when the remaining capacity SOCN is larger than the target remaining capacity SOCT (SOCT−SOCN <0), as shown by a broken line in FIG. 4, the basic power generation torque Tb is slid in the torque axis direction so as to decrease by a set amount. The power generation torque instruction value is used.

  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.

  This power generation control routine is a program process executed every predetermined time or every predetermined cycle. First, in the first step S1, the presence or absence of the latest data input such as the remaining capacity SOCN of the battery 4 and the engine speed N is checked. Investigate. As a result, if there is no new data input in step S1, the routine is directly exited, and if there is new data input, the process proceeds from step S1 to step S2.

  In step S2, it is checked whether or not the current remaining capacity SOCN is equal to or higher than the upper limit SOCMAX. The upper limit SOCMAX is a threshold value for the remaining capacity at which the battery 4 can be used in a normal state and charging is stopped, and is set to, for example, about 80% of full charge. As a result, if SOCN <SOCMAX, the process proceeds from step S2 to step S3, and whether or not the difference SOCD (SOCD = SOCT−SOCN) between the current remaining capacity SOCN and the preset target remaining capacity SOCT is 0 or more. Check out.

  In step S3, if SOCD ≧ 0, the power generation amount is instructed up in step S4 and the routine is exited. If SOCD <0, the power generation amount is instructed down in step S5 and the routine is exited. As described with reference to FIG. 4, the power generation amount is increased by the indicated value obtained by sliding the basic power generation torque Tb in the increasing direction by the slide amount determined by the difference SOCD between the target remaining capacity SOCT and the remaining capacity SOCN. The down is performed by an instruction value obtained by sliding the basic power generation torque Tb in the decreasing direction by the slide amount determined by the difference SOCD between the target remaining capacity SOCT and the remaining capacity SOCN.

  Note that the slide amount of the basic power generation torque Tb in the power generation amount up / down instruction is not only the set amount determined based on the difference SOCD between the target remaining capacity SOCT and the remaining capacity SOCN, but also the set amount considering the engine efficiency. By taking into account, it is possible to contribute to further improvement in fuel consumption.

  On the other hand, if SOCN ≧ SOCMA in step S2, the process proceeds from step S2 to step S6 to output a power generation stop instruction and immediately stop power generation. Then, in step S7, the presence or absence of the latest data such as the remaining capacity SOCN of the battery 4 and the engine speed N is checked again. If the routine is exited and data is input, it is checked in step S8 whether the remaining capacity SOCN has dropped below the target remaining capacity SOCT.

  As a result, if SOCN> SOCT and the remaining capacity SOCN still exceeds the target remaining capacity SOCT, the process returns to step S7 while continuing to stop power generation in step S9. If SOCN ≦ SOCT, step S3 described above is continued. Proceeding thereafter, the power generation amount is instructed to be increased or decreased according to the difference between the target remaining capacity SOCT and the remaining capacity SOCN. In other words, when the remaining capacity SOCN becomes equal to or higher than the upper limit SOCMAX (SOCN ≧ SOCMAX) depending on the traveling state, the power generation is immediately stopped and the power generation is postponed until SOC ≦ SOCT.

  As described above, in the present embodiment, the basic power generation torque is set in consideration of the required power of the entire vehicle and the power generation efficiency in each operation region. Since the power generation torque command value is set by increasing or decreasing according to the difference from the remaining capacity, it is possible to realize optimal power generation control, and to improve fuel efficiency while securing the required power generation amount .

  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 Explanatory diagram in which the amount of power generation is converted into the relationship between engine speed and power generation torque Explanatory diagram showing the shift in power generation amount according to the operating region Explanatory drawing showing slide of power generation amount Flow chart of power generation control routine

Explanation of symbols

1 Engine 2 Motor 4 Battery 50 Hybrid controller (basic power generation torque setting means, power generation instruction means)
N Engine speed Pb Power generation amount (required power of the entire vehicle)
Tb Basic power generation torque SOCN remaining capacity SOCT Target remaining capacity SOCMAX upper limit

Claims (5)

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, charges the power storage device that drives the motor by the engine and supplies power to the motor. ,
A basic power generation torque setting means for setting a basic power generation torque using the engine speed as a parameter, based on the required power of the entire vehicle in consideration of equipment efficiency and the power generation efficiency for each operation region;
A power generation instructing unit configured to increase or decrease the basic power generation torque according to at least a difference between a remaining capacity of the power storage device and a preset target remaining capacity, and to set a power generation torque instruction value of the power unit; Control device for hybrid vehicles. The basic power generation torque setting means is:
2. The basic power generation torque is set by decreasing the power generation torque in an engine speed region having a low power generation efficiency while increasing the power generation torque in an engine speed region having a high power generation efficiency. Control device for hybrid vehicles. The power generation instruction means
3. The control apparatus for a hybrid vehicle according to claim 1, wherein the power generation torque instruction value is set in consideration of the efficiency of the engine in addition to the difference between the remaining capacity of the power storage device and the target remaining capacity. . The power generation instruction means
When the remaining capacity of the power storage device is equal to or less than the target remaining capacity, the basic power generation torque is slid so that the basic power generation torque is uniformly increased with respect to the engine speed, and the power generation torque instruction value is increased. When the remaining capacity of the device exceeds the target remaining capacity, the basic power generation torque is slid so that the basic power generation torque is uniformly reduced with respect to the engine speed, thereby reducing the power generation torque instruction value. The hybrid vehicle control device according to any one of claims 1 to 3. The power generation instruction means
The power generation by the power unit is immediately stopped when the remaining capacity of the power storage device exceeds an upper limit value, and the power generation stop is continued until the remaining capacity of the power storage device is reduced to the target remaining capacity. The control apparatus of the hybrid vehicle as described in any one of 1-4.

Images