JP2000125413A - Hybrid vehicle and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control torque output to axles with accuracy, by taking a motoring torque for starting or stopping an engine as the target torque of a first motor, and setting and controlling the target torque of a second motor based on a requested torque and a reaction torque. SOLUTION: When an engine is started, that is, when an engine 150 is subjected to motoring by a motor MG1, the target torque of the motor MG1 is set to a predetermined value, that is, a motoring torque until the revolution of the engine 150 reaches a specified value suitable for self-sustaining drive. The target torque of a motor MG2 is set and controlled so that reaction torque outputted to a ring gear shaft 126 as the reaction torque of the motor MG1 can be compensated and the target torque can be outputted from an axle 112. As a result, the reaction torque can be calculated with accuracy in the low rpm ranges of the engine 150 and thus fluctuation in torque output to the axle can be appropriately controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid vehicle having an engine and an electric motor and capable of running using at least the power output from the engine as a power source, and a control method therefor.

[0002]

2. Description of the Related Art In recent years, hybrid vehicles having an engine and an electric motor have been proposed. Various configurations have been proposed as such a hybrid vehicle, one of which is a parallel hybrid vehicle. In a parallel hybrid vehicle, both the power of the engine and the power of the electric motor can be transmitted to the axle. FIG. 1 shows a configuration example of a parallel hybrid vehicle.

In the hybrid vehicle shown in FIG.
50, and electric motors MG1 and MG2. The three are mechanically connected via a planetary gear 120. The planetary gear 120 is also called a planetary gear and has three rotation shafts connected to respective gears described below. The gears that make up the planetary gear 120 are:
A sun gear 121 rotates at the center, a planetary pinion gear 123 revolves around the sun gear while rotating around the sun gear, and a ring gear 122 rotates around the outer periphery. The planetary pinion gear 123 is supported by a planetary carrier 124. In the hybrid vehicle of FIG. 1, engine 150 is coupled to planetary carrier 124. The electric motor MG1 is connected to the sun gear 121.
Electric motor MG <b> 2 is connected to ring gear 122. The ring gear 122 is connected to the axle 11 by the chain belt 129.
2 are connected.

[0004] In the hybrid vehicle having such a configuration, the power output from the engine is transmitted to the planetary gears 12.
At 0, it is split into two. A part thereof is transmitted to the axle 112 as mechanical power. The remaining portion is regenerated as electric power by electric motor MG1. The power distribution ratio is determined based on the gear ratio of the planetary gear 120, and a constant power corresponding to the vehicle speed is regenerated as electric power by the electric motor MG1.
If the torque transmitted to axle 112 is less than the required value, electric motor MG2 outputs a shortage of torque. Electric power regenerated by electric motor MG1 is used for driving electric motor MG2. By such an operation, the hybrid vehicle can run by converting the power output from the engine into the power consisting of the torque and the number of revolutions required for the axle 112. In a hybrid vehicle, the electric motor M
It is also possible to drive with the engine stopped using the power of G2.

[0005] Further, even when the vehicle is stopped or running, the motor MG1 can be driven to start the motor and start the engine by driving the electric motor MG1. In the hybrid vehicle having the above-described configuration, when torque for motoring the engine is output from electric motor MG1, part of the torque is transmitted to axle 112 through the planetary gear. The electric motor MG2 is controlled so as to compensate for the torque transmitted from the electric motor MG1 to the axle 112 and output the required torque.

[0006] The target torque of the electric motor MG2 in this control is set based on the difference between the required torque to be output from the axle 112 and the reaction torque transmitted from the electric motor MG1 to the axle 112. Here, when the engine is started, the rotation speeds of the engine and the electric motor MG1 greatly change. It is generally known that when the rotation speed changes, a torque corresponding to the product of the change rate and the inertia performance rate is required. Therefore, when starting the engine, a part of the torque output from the electric motor MG1 is used to change the rotation speed of the system including the engine and the electric motor MG1, and causes a kind of torque loss. When calculating the torque transmitted from the electric motor MG1 to the axle 112 to set the target torque of the electric motor MG2, not only the balance of the static torque via the planetary gears but also the above-mentioned reaction torque is taken into account. There is a need.

[0007] The present applicant has previously disclosed in Japanese Patent Application Laid-Open No. 10-98805.
Discloses a technique for setting the target torque of the electric motor MG2 in consideration of the torque loss. Such technology is
The target torque of the motor MG2 is set after calculating the torque loss based on the product of the change in the rotation speed of the motor MG1 and the inertia rate of the motor MG1. Further, based on the fact that the motor MG1 and the engine speed have a fixed relationship according to the gear ratio of the planetary gears, there is also a technique for calculating the torque loss by the product of the change in the engine speed and the engine inertia rate. It has been disclosed.

[0008]

However, in the prior art, the detection accuracy of the rotational speeds of the electric motor MG1 and the engine is low, and the torque loss and the reaction torque cannot be obtained with sufficient accuracy. For this reason, the target torque of the electric motor MG2 cannot be set with high accuracy, and sudden fluctuations in the torque output to the axle when the engine starts and stops,
A so-called torque shock occurred.

Consider a case where torque loss is calculated based on a change in the number of revolutions of motor MG1. The rotation speed of the electric motor MG1 changes in a wider range than that of the engine. For detecting the rotation speed of the electric motor MG1, a sensor capable of detecting the rotation speed in a wide range is required. Such a sensor having a wide detection range generally has a low resolution at which the rotation speed can be detected.
Therefore, the rotation speed of the electric motor MG1 at the time of relatively low rotation such as at the time of starting the engine could not be accurately detected.

The electric motor MG1 can rotate in both positive and negative directions. Therefore, when detecting the number of rotations, it is necessary to determine in which direction the motor is rotating. Since the determination process is required, it takes a long time to detect the rotation speed of the electric motor MG1, and in some cases, the control process for setting the target torque of the electric motor MG2 cannot be sufficiently followed. Further, depending on the relationship between the rotation speed of the electric motor MG1 and the sampling interval of the sensor for detecting the rotation speed, it is very difficult to determine whether the rotation speed is positive or negative, and the positive or negative may be erroneously determined.

On the other hand, the change in the engine speed is relatively narrow and the engine rotates only in the forward direction. However, the rotation of the engine is not stable at a low rotation speed. Therefore, in the initial stage of starting the engine, the torque loss could not be accurately obtained.

The above description has exemplified the case where the engine is started by the electric motor MG1. In hybrid vehicles,
When it is determined that the operation of the engine is unnecessary, the engine may be stopped even while the vehicle is running. There is a case where the driving state is switched from the driving state involving the operation of the engine to the driving state using only the electric motor without the engine. Of course, there is a case where the operation of the engine is stopped while the vehicle is stopped. In these cases, a braking torque for stopping the engine is output from electric motor MG1. Even in such a case, in order to set the target torque of the electric motor MG2, it is necessary to calculate the reaction torque output from the electric motor MG1 to the axle, and the same problem as in starting the engine has arisen.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an object of the present invention to provide a technique for accurately controlling a torque output to an axle when starting and stopping an engine in a so-called parallel hybrid vehicle. Aim.

[0014]

Means for Solving the Problems and Their Functions and Effects In order to solve at least a part of the above problems, the present invention has the following constitution. The hybrid vehicle of the present invention
The engine, the first electric motor, and the axle are connected to each of the rotating shafts of the power distribution device in which the rotating state of the remaining rotating shaft is uniquely determined according to the rotating state of two of the rotating shafts. A hybrid vehicle in which a second electric motor is coupled to an axle, wherein input means for inputting a required torque to be output from the drive shaft and motoring torque for starting or stopping the engine are transmitted to the first motor. First target torque setting means for setting as a target torque of the electric motor, and a reaction torque output to the axle by the first electric motor when adding the motoring torque, the motoring torque and the engine Estimating means for estimating the target torque of the second electric motor based on the required torque and the reaction torque. And stage, the first motor and the second
And control means for controlling the electric motors and outputting respective target torques.

In such a hybrid vehicle, when a motoring torque for starting or stopping the engine is output from the first electric motor, a reaction torque is estimated based on the motoring torque and the rotational resistance of the engine. When starting or stopping the engine, the engine is not in a so-called self-sustaining operation, and is in a state of being motored by the torque from the first electric motor or the like. Rotational resistance refers to the torque required to rotate the engine with external force. In other words, it can be translated into negative torque output from the engine. The rotational resistance of the engine in such a state is mainly determined by friction, and has a known value according to the rotational state of the engine. Therefore, according to the hybrid vehicle described above, the reaction torque can be accurately determined in consideration of the torque lost in motoring, and the target torque of the second electric motor can be accurately set. As a result, in the hybrid vehicle, a smooth operation can be realized without generating a torque shock when the engine is started and stopped.

Here, the reason why the reaction torque can be calculated in consideration of the torque loss based on the rotational resistance of the engine will be described. As described above, the torque loss refers to the torque consumed for changing the rotation speed of the first electric motor and the engine. Since the power distribution device has an unambiguous relationship between the rotation states of the three rotation shafts, either one of the torque spent for changing the rotation speed of the first electric motor and the torque used for changing the rotation speed of the engine is reduced. Once determined, the torque loss can be determined. Here, attention is paid to the torque consumed for changing the engine speed. The torque consumed here is determined by the product of the rate of change of the engine speed and the rate of inertia of the engine. When the engine is not operating independently, this torque is equal to the difference between the torque externally applied to the engine and the rotational resistance caused by friction of the engine. The torque externally applied to the engine can be calculated based on the torque output from the first electric motor. Further, the rotational resistance of the engine is a known value. Therefore, when the engine is not operating independently, the torque consumed for changing the engine speed can be determined based on these values.

Here, when the rotational state of the engine is within a predetermined range, the estimating means may be means for performing the estimation with the rotational resistance being a constant value. The rotational resistance of the engine is mainly the viscous resistance of the lubricating oil inside the engine and other mechanical frictional resistance. It is known that these values become substantially constant when the rotation state of the engine is within a predetermined range.
Note that the predetermined range is different depending on the characteristics of the engine.

Further, there is provided a temperature detecting means for detecting a temperature of the lubricating oil of the engine, and a storing means for storing a relationship between the temperature and the rotational resistance, wherein the estimating means refers to the storing means. May be a means for performing the estimation by using the rotation resistance obtained according to the temperature.

The viscosity resistance of the lubricating oil, which is the main factor of the rotational resistance, changes according to the temperature. According to the hybrid vehicle having the above configuration, a value corresponding to the temperature of the lubricating oil can be used as the rotational resistance, so that the torque loss can be obtained with higher accuracy.

The temperature of the lubricating oil can be detected by various methods. A temperature sensor may be provided directly inside the tank where the lubricating oil of the engine is stored to detect the temperature of the lubricating oil directly, or the temperature of the lubricating oil may be detected indirectly by detecting the temperature of the cooling water of the engine It may be. Of course, in the latter case, the storage means may store the relationship between the cooling water temperature and the rotation resistance. The temperature of the lubricating oil may be estimated according to the elapsed time from when the engine starts operating, the elapsed time after stopping the operation, or the like. In this sense, the hybrid vehicle can use not only the temperature of the lubricating oil but also various parameters related to the rotational resistance of the engine. For example, the rotational resistance may be obtained from the operation history of the engine until the control of the present invention is executed.

[0021] The hybrid vehicle of the present invention further comprises a detecting means for detecting the number of revolutions of the engine,
The estimating means may be means for performing estimation based on the motoring torque and the rotational resistance only when the rotational speed is equal to or less than a predetermined value.

The rotational resistance of the engine has a substantially constant value in a low rotational speed region. According to the hybrid vehicle, when the engine speed is equal to or lower than a predetermined value, the loss based on the motoring torque and the rotation resistance are estimated, thereby accurately detecting the torque loss and the reaction torque. Can be.

In an area where the engine speed is higher than a predetermined value, the torque loss and the reaction torque can be calculated by various methods. In a region where the engine rotates almost constantly, the loss of torque is small and may be neglected. As a method of calculating the reaction force torque in consideration of the torque loss, for example, as described in the related art, means using the rate of change in the rotation speed of the first electric motor can be applied. Further, the reaction force torque may be estimated based on the motoring torque and the rate of change of the engine speed. In this case, the torque loss is a value proportional to the product of the change in the engine speed and the engine inertia rate.

Any of the means can accurately determine the torque loss in a region where the rotational speed is relatively high. The latter means has the advantage that the detection accuracy of the engine speed is high and it is not necessary to determine whether the engine speed is positive or negative, so that the torque loss and the reaction torque can be more appropriately obtained.

In the hybrid vehicle according to the present invention, there is provided a determining means for determining whether or not the vehicle is stopped, and the estimating means is configured to determine whether the motoring torque and the rotation are reduced only when the vehicle is stopped. It may be a means for performing estimation based on the resistance.

During a stop, it is necessary to maintain a constant torque output to the axle. When the vehicle is stopped on a flat place, the torque is maintained at a constant value of 0, and when traveling uphill, the torque is maintained at a constant value having a positive value corresponding to the gradient. In any case, if the torque output to the axle fluctuates, the vehicle vibrates. Generally, when stopped, the occupants are very sensitive to vehicle vibration. The hybrid vehicle of the present invention can suppress the torque shock generated in the vehicle when the engine is started and stopped, and thus is particularly effective when the vehicle is stopped.

The determination as to whether or not the vehicle is stopped can also be made based on, for example, whether or not the shift position is at a position such as a parking range used only when the vehicle is stopped. Further, the determination means may specify whether or not the vehicle is stopped based on a vehicle speed.

Even when the shift position is in a position used during traveling, there is a possibility that the hybrid vehicle is stopped, for example, when a brake is depressed. According to the above-described specifying means, even in such a case, it is possible to specify that the vehicle is stopped, so that it is possible to more reliably improve the riding comfort during stopping. Further, according to the above-described specific means, it is possible to treat the vehicle as stopped even when the vehicle is traveling at a very low speed without being completely stopped. When traveling at very slow speeds, occupants are sensitive to vehicle vibration. According to the determination means, even in such a case, by treating the vehicle as being stopped, it is possible to suppress the vibration when traveling at a very low speed.

Normally, a hybrid vehicle has a plurality of axles. The hybrid vehicle of the present invention can adopt a configuration in which the power distribution device and the electric motor are coupled to the same axle. Further, the axle to which the power distribution device is coupled and the axle to which the electric motor is coupled are different axles, and adopt a configuration capable of driving four wheels by outputting power from wheels coupled to each axle. It is also possible.

Naturally, the power distribution device and the electric motor may be connected to one axle, and the electric motor may be connected to another axle to adopt a configuration capable of driving four wheels. Further, the present invention may be applied to a hybrid vehicle in which the connection destination of the second electric motor can be variously switched using a mechanism such as a clutch and a spline. Switching of the connection destination of the second electric motor may be performed, for example, between the axle to which the power distribution device is connected and the rotation shaft of the engine.

The present invention can also be configured as a hybrid vehicle control method described below. That is, the engine, the first electric motor, and the axle are provided on each of the rotating shafts of the power distribution device in which the rotating states of the remaining rotating shafts are uniquely determined according to the rotating states of two of the three rotating shafts. And a second electric motor coupled to the axle, the method comprising: (a) inputting a required torque to be output from the drive shaft;
Setting a motoring torque for starting or stopping the engine from the electric motor as a target torque of the first electric motor; and (c) setting the axle by the first electric motor when adding the motoring torque. Estimating the reaction torque output to the second motor based on the motoring torque and the rotational resistance of the engine; and (d) taking into account the required torque and the reaction torque, the target of the second electric motor. Setting a torque; and (e) setting the first
Controlling the electric motor and the second electric motor to output respective target torques.

If the operation of the hybrid vehicle is controlled by such a control method, control excellent in operability and riding comfort of the vehicle can be realized by the same operation as the operation described above as the invention of the hybrid vehicle. .

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples. (1) Configuration of Embodiment: First, the configuration of a hybrid vehicle as an embodiment of the present invention will be described. FIG. 1 is an explanatory diagram showing a configuration of a power system that outputs power of the hybrid vehicle. The engine 150 provided in the power system is a normal gasoline engine, and has a crankshaft 156.
To rotate. The operation of the engine 150 is EFIECU1
70. The EFIECU 170 is a one-chip microcomputer having a CPU, a ROM, a RAM, and the like therein, and the CPU executes a fuel injection amount of the engine 150 and other controls according to a program recorded in the ROM.

The power system includes motors MG1, MG2
Is provided. The motors MG1 and MG2 are synchronous motors, and have a rotor 13 having a plurality of permanent magnets on the outer peripheral surface.
2 and 142, and stators 133 and 143 around which a three-phase coil forming a rotating magnetic field is wound. Stator 13
3 and 143 are fixed to the case 119. Motor M
The three-phase coils wound around the stators 133 and 143 of G1 and MG2 are connected to the battery 194 via drive circuits 191 and 192, respectively. Drive circuit 191, 1
Reference numeral 92 denotes a transistor inverter provided with a pair of transistors as switching elements for each phase. The drive circuits 191 and 192 are connected to the control unit 190. When the transistors of drive circuits 191 and 192 are switched by a control signal from control unit 190, current flows between battery 194 and motors MG1 and MG2. The motors MG1 and MG2 can also operate as electric motors that receive the supply of power from the battery 194 and rotate (hereinafter, this running state is referred to as power running), and when the rotors 132 and 142 are rotated by external force. In addition, the battery 194 can be charged by functioning as a generator for generating an electromotive force at both ends of the three-phase coil (hereinafter, this running state is referred to as regeneration).

The engine 150 and the motors MG1 and MG2 are mechanically connected via a planetary gear 120, respectively. The planetary gear 120 includes a sun gear 121,
It comprises a planetary carrier 124 having a ring gear 122 and a planetary pinion gear 123. In the hybrid vehicle of the present embodiment, the crankshaft 156 of the engine 150 is connected to the planetary carrier shaft 127 via the damper 130. The damper 130 is provided to absorb torsional vibration generated in the crankshaft 156. The rotor 132 of the motor MG1 is connected to the sun gear shaft 125. The rotor 142 of the motor MG2 is connected to the ring gear shaft 126. The rotation of the ring gear 122 is transmitted to the axle 112 and the wheels 116R and 116L via the chain belt 129.

The overall operation of the hybrid vehicle of the embodiment is controlled by the control unit 190. The control unit 190 has a CPU,
This is a one-chip microcomputer having a ROM, a RAM, and the like. The control unit 190 is the EFI ECU 17
0 is connected to each other, and both can transmit various information. The control unit 190 includes the engine 15
By transmitting information such as a torque command value and a rotation speed command value necessary for the control of 0 to the EFIECU 170,
The operation of the engine 150 can be controlled indirectly. Further, by controlling the switching of the drive circuits 191 and 192, the operation of the motors MG1 and MG2 can be directly controlled. The control unit 190 thus controls the operation of the entire hybrid vehicle. To realize such control, the control unit 190 includes various sensors, for example, an accelerator pedal position sensor 16 for detecting the amount of depression of the accelerator by the driver.
5, a shift position sensor 167 for detecting the position of the shift lever, an engine water temperature sensor 158 for detecting the temperature of the cooling water of the engine 150, a sensor 144 for knowing the rotation speed of the axle 112, and the like. Since the ring gear shaft 126 and the axle 112 are mechanically connected, in this embodiment, a sensor 144 for detecting the rotation speed of the axle 112 is provided on the ring gear shaft 126, and the motor MG2
It is common with the sensor for controlling the rotation of.

(2) Basic operation: In order to explain the basic operation of such a hybrid vehicle, first, the operation of the planetary gear 120 will be described. FIG. 2A is a diagram schematically illustrating the planetary gear 120. As described above, the planetary gear 120 includes the sun gear 121 that rotates at the center, three planetary pinion gears 123 that revolve around the periphery thereof, and a ring gear 122 that rotates around the outer periphery thereof. The planetary pinion gear 123 is supported by a planetary carrier 124. The planetary gear 120 has such a property that, when the rotation speed and the torque of two of the above-mentioned three rotation shafts (hereinafter, collectively referred to as a rotation state) are determined, the rotation state of the remaining rotation shafts is determined. have. It is known that the following equation (1) holds for the number of rotations of each rotating shaft.

Nr = (1 + ρ) Nc−ρNs; Nc = (Nr + ρNs) / (1 + ρ); Ns = (Nc−Nr) / ρ + Nc; (1) where Ns is the rotation speed of the sun gear shaft 125 and Nr is Nc is the rotation speed of the ring gear shaft 126 and Nc is the rotation speed of the planetary carrier shaft 127. Ρ is a gear ratio between the sun gear 121 and the ring gear 122 as represented by the following equation. ρ = number of teeth of sun gear 121 / number of teeth of ring gear 122

On the other hand, the relationship between the torques is derived from the following equation of motion. First, variables are defined as shown in FIG. In other words, the moment of inertia is represented by I, the angular acceleration is represented by β, the torque is represented by T, and the radius is represented by R.
"S", "c" for the planetary carrier 124, and "r" for the ring gear 122. Further, the reaction force acting between the ring gear 122 and the planetary pinion gear 123 is represented by Fr, and the reaction force acting between the planetary pinion gear 123 and the sun gear 121 is represented by Fs. In addition, the respective inertia factors are not only the inertia ratio of the gear, but also the motors MG1 and MG1 coupled thereto.
It means a value including the inertia performance factor of MG2 and engine 150.

At this time, the equation of motion of each gear is represented by the following equation (2). Is · βs = Ts−3Rs · Fs; Ic · βc = Tc + 3Rs · Fs−3Rr · Fr; Ir · βr = Tr + 3Rr · Fr; (2)

Here, it is considered that the planetary pinion gear 123 has an inertia coefficient of approximately zero. At this time, since the moment acting on the planetary pinion gear 123 should be 0, Fs = −Fr. The relationship between the gear ratio ρ and the radius used above is ρ = Rs / Rr.
Further, Ta = 3 (Rs · Fs−Rr · Fr).
This means torque acting on the sun gear 121 and the ring gear 122 from the planetary carrier 124 by the reaction forces Fs and Fr acting between the respective gears. Substituting these quantities into the above equation (2) gives the following equations (3) to (5)
Can be obtained.

Is · βs = Ts−ρ · Ta / (1 + ρ) (3) Ic · βc = Tc−Ta (4) Ir · βr = Tr + Ta / (1 + ρ) (5) From equation (1), the angular velocities βs, βc, β
The following equation (6) holds between r. βc = (βr + ρβs) / (1 + ρ) (6)

Equations (3) to (6) are equivalent to the planetary gear 120
Is an equation that gives the rotational state of. Equation (1) may be used instead of equation (6). In these four equations, there are seven variables βs, βc, βr, Ts, Tc, Tr and Ta. Therefore, of these seven variables,
If three independent variables are specified, the planetary gear 12
A rotation state of 0 is uniquely defined. Depending on the values of these variables, the planetary gear 120 can rotate in various states, such as rotating one gear while the other gear is stopped. In the hybrid vehicle of the present embodiment,
Using the above equation, the motors MG1, MG2 and the engine 15
The target values of the rotation speed and the torque of 0 are set, and the respective operations are controlled. The control method will be described later in detail.

The hybrid vehicle of this embodiment can run in various states based on the action of the planetary gear 120 shown by the above equation. For example, when the hybrid vehicle starts running at a relatively low speed, the engine 15
While the motor MG2 is stopped, the motor MG2 is driven by power to transmit power to the axle 112 and travel. Similarly, the vehicle may travel with the engine 150 idling.

When the hybrid vehicle reaches a predetermined speed, the control unit 190 motors and starts the engine 150 with the torque output by powering the motor MG1. At this time, the reaction torque of the motor MG1 is also output to the ring gear 122 via the planetary gear 120. The control unit 190 controls the motor M so that the required power is output from the axle 112 while canceling the reaction torque.
The operation of G2 is controlled.

When the engine 150 is operating,
The power is converted into various rotation speeds and torques and output from the axle 112 to travel. Engine 150
Is driven to rotate the planetary carrier shaft 127, the sun gear shaft 125 and the ring gear shaft 126 rotate under the conditions satisfying the above equations (3) to (6). The power generated by the rotation of the ring gear shaft 126 is directly applied to the wheels 116.
R, 116L. Power generated by rotation of the sun gear shaft 125 can be regenerated as electric power by the motor MG1. On the other hand, if the motor MG2 is powered, power can be output to the wheels 116R and 116L via the ring gear shaft 126. From the engine 150 to the ring gear shaft 12
If the torque transmitted to the motor MG6 is insufficient, the motor MG2
Assists torque by powering. Motor M
As power for powering G2, power regenerated by motor MG1 and power stored in battery 149 are used.
Control unit 190 controls the operation of motors MG1 and MG2 according to the required power to be output from axle 112.

The planetary gear 120 is a ring gear 12
With the 2 stopped, the planetary carrier 124 and the sun gear 121 can be rotated. Therefore, engine 150 can be operated even when the vehicle is stopped. For example, when the remaining capacity of the battery 194 is low, the battery 194 can be charged by operating the engine 150 and regenerating the motor MG1. If the motor MG1 is run when the vehicle is stopped, the engine 150 can be motored and started with the torque. At this time, the control unit 1
90 controls the motor MG2 to cancel the reaction torque of the motor MG1.

(3) Torque control processing: Next, the torque control processing in this embodiment will be described. The torque control process is a process of controlling the engine 150 and the motors MG1 and MG2 to output power including the requested torque and rotation speed from the axle 112. FIG. 3 shows a flowchart of the torque control process in this embodiment. This routine is repeatedly executed at predetermined time intervals by a timer interrupt by a CPU (hereinafter simply referred to as CPU) in the control unit 190.

When the torque control routine is started, CP
U first executes a traveling state determination process (step S1).
0). As described above, the hybrid vehicle of the present embodiment can run by driving the engine and the motors MG1 and MG2 in various states. The driving states of the three parties are properly used according to the running state of the hybrid vehicle. In order to properly use the vehicle, the CPU determines the running state of the vehicle when the torque control routine is started.

FIG. 4 shows a flowchart of a running state determination processing routine. In this process, the CPU first inputs a shift position (step S20). The shift position can be detected by the shift position sensor 167 shown in FIG. In the present embodiment, as the shift position, a P range used for parking, a D range and a B range used for forward running, an R range used for reverse running, and a neutral position are prepared. CP at the same time
U inputs the vehicle speed, the accelerator pedal position, and the remaining battery charge Sch (step S20).

Next, the CPU determines the running state of the vehicle according to the following procedure. First, it is determined whether the shift position is in the P range (step S30). Further, it is determined whether or not the accelerator is fully closed and the vehicle speed is lower than a predetermined speed V1 (step S35). If one of these conditions is satisfied, it is determined that the vehicle is stopped (step S40). The determination result is stored by inputting a code indicating that the vehicle is stopped into a predetermined flag indicating the traveling state.

The predetermined speed V1 is set in advance to a very low speed at which the vehicle can be considered to be stopped. By determining whether or not the vehicle is stopped using not only the shift position but also the vehicle speed, it is also determined that the vehicle is stopped when the vehicle is stopped with the brakes depressed at the shift position such as the D range or the B range. You.

If the conditions of both steps S30 and S35 are not satisfied, it is next determined whether or not the remaining capacity Sch of the battery 194 is smaller than a predetermined value CH1 (step S45). If the remaining capacity Sch is smaller than the predetermined value CH1, it is determined whether or not the engine 150 is operating (step S50). If the engine is not operating, the battery 150 is charged. It is determined that the vehicle is in the running state in which the engine 150 should be started (step S55). The predetermined value CH1 is determined by the battery 19
4 is a lower limit value of the remaining capacity as a criterion for determining whether to start charging.

In step S45, the battery 194
If the remaining capacity Sch is equal to or greater than the predetermined value Ch1,
Next, it is determined whether the remaining capacity Sch is larger than a predetermined value CH2 (step S60). If it is larger than the predetermined value CH2, it is determined whether or not the engine 150 is stopped (step S65). It is determined that there is (Step S70). The determination result about the running state is stored in a predetermined flag. CPU
When the above processing is executed, the running state determination processing routine ends, and the process returns to the torque control routine.

Actually, in the running state determination processing routine, various other running states are determined. For example, a determination is made as to EV running in which the vehicle runs without driving the engine, or running in a mode in which the engine is started. These determinations are made based on various conditions such as the vehicle speed and the state of charge of the battery 194. A detailed description of such determination processing is omitted.

When the running state is determined, the CPU sets the axle 1
Twelve target revolutions Nd * and target torque Td * are set (step S100). The target rotation speed Nd * and the torque Td * are set according to the current vehicle speed, the accelerator depression amount, and the like. The target rotation speed Nd * thus set
And the torque Td *, the CPU
A required power Pe * of 0 is set (step S110).
Required power Pe * of engine 150 varies depending on the running state of the vehicle. The running state can be detected by a code stored in the flag set in the running state determination process. When the vehicle is stopped or running on an EV, the axle 11
Regardless of the target rotation speed Nd * and the torque Td *, the required power Pe * of the engine 150 basically has a value of 0. However, even in such a case, if it becomes necessary to charge the battery 194, the power required for charging is set as the required power Pe * of the engine 150.

When the hybrid vehicle is running normally, the required power Pe * of the engine 150 is
Of the target rotation speed Nd * and the torque Td *, the electric power charged / discharged from the battery 194, and the electric power required for driving the auxiliary equipment. For example, when surplus power needs to be discharged from battery 194, required power Pe * to engine 150 can be reduced accordingly. Further, when operating an auxiliary machine such as an air conditioner, it is necessary to output an extra power from the engine 150 in addition to the traveling power from the engine 150.

Thus, the required power Pe to the engine 150
When * is set, the CPU sets the operating point of the engine 150, that is, the target rotation speed Ne * and the target torque Te * (step S120). The operating point of engine 150 is basically set by selecting an operating point at which the operating efficiency is the best from the map.

FIG. 5 shows the relationship between the operating points of the engine 150 and the operating efficiency. The curve B in the figure represents the engine 150
Indicates limit values of operable speed and torque. Curves indicated by α1%, α2%, etc. in FIG.
Each is an iso-efficiency line at which the efficiency of the engine 150 is constant, and indicates that the efficiency decreases in the order of α1% and α2%. As shown in FIG. 5, the efficiency of the engine 150 is high at a relatively limited operating point, and the efficiency gradually decreases at operating points around the engine.

In FIG. 5, the curves indicated by C1-C1, C2-C2, and C3-C3 are curves in which the power output from engine 150 is constant, and the operating point of engine 150 is determined by the required power. Selection will be made on these curves accordingly. C1-C1, C2-C2, C3-C3
, The power demand is lower. For example, when the required power Pe * to the engine 150 corresponds to the power represented by the curve C1-C1, the operating point of the engine 150 is A1 at which the operating efficiency is highest on the curve C1-C1.
Set to a point. Similarly, the operation point is selected at point A2 on the C2-C2 curve and at point A3 on the C3-C3 curve. FIG. 6 shows the relationship between the rotation speed of the engine 150 and the operating efficiency on the curves C1-C1, C2-C2, and C3-C3.
Shown in The curves in FIG. 6 illustrate three curves in FIG. 5 for convenience of description, but are curves that can be drawn countlessly in accordance with the required output. There are countless choices.
A curve drawn by connecting points having a high operating efficiency of the engine 150 is a curve A in FIG. 5, which is called an operation curve.

When the required power Pe * of the engine 150 is 0, the engine 150 is stopped or in an idling state. For example, this corresponds to a case where the hybrid vehicle travels using only the power from the motor MG2, or a traveling state such as when going downhill. Whether the engine 150 is stopped or idling is set based on various conditions. At relatively high vehicle speeds, engine 150 runs idle based on the restrictions previously described in FIG. Also, the idle operation is performed when it is determined that the engine 150 needs to be warmed up.

The engine 15 set by the above processing
Based on the 0 operation point, the CPU sets the target rotation speed N1 * and the torque T1 * of the motor MG1 (step S130). Since the target rotation speed N1 * of the engine 150, that is, the planetary carrier shaft 127, and the target rotation speed Nd * of the axle 112, that is, the ring gear shaft 126, are set, the target of the sun gear shaft 125, that is, the motor MG1 is obtained by the above equation (1). The rotation speed N1 * can be set.

The setting of the target torque T1 * of the motor MG1 differs depending on the running state of the hybrid vehicle. When the hybrid vehicle is stopped or running in the EV mode, the target torque T1 * of the motor MG1 becomes 0. When the engine starts, that is, when the motor 1
When the motor 50 is motored, the target torque T1 * of the motor MG1 is set to a predetermined value by open loop control until the rotation speed of the engine 150 reaches a predetermined rotation speed suitable for self-sustaining operation. This value is called motoring torque.

When engine 150 is operating independently, target torque T1 * of motor MG1 is basically set by so-called proportional-integral control. The target torque T1 * is set based on the deviation between the current rotation speed of the motor MG1 and the above-described target rotation speed N1 *. If the current rotational speed is lower than the target rotational speed N1 *, the target torque T1 * is a positive torque, and if the current rotational speed is the opposite, the negative torque is a negative torque. The gain used when setting the torque T1 * can be set by experiments or the like.

The CPU sets the operation point of the motor MG2, that is, the target rotation speed N2 * and the target torque T2 * based on the operation point of the engine 150 and the operation point of the motor MG1 set in the above processing (step S200). . The target rotation speed N2 * of the motor MG2 is equal to the target rotation speed Nd * of the ring gear shaft 126.

The target torque T2 * is set by the MG2 target torque setting routine based on the target torque Td * to the axle 112 and the reaction torque from the motor MG1. FIG. 7 shows a flowchart of this setting processing routine. In this process, the CPU inputs the target torque Td * of the axle (step S202). The engine speed Ne and the water temperature are also input (step S20).
4).

The target torque of MG2 is the reaction torque s output to ring gear shaft 126 as the reaction torque of MG1.
The target torque Td * is set to be output from the axle by compensating for the step. The reaction torque step is not only a static torque balance between the respective gears of the planetary gear 120 but also a counterforce acting between the respective gears of the planetary gear 120 based on the equations (3) to (6) shown above. It is calculated by obtaining the torque caused by the force. By doing so, of the torques output from motor MG1, reaction force torque step can be obtained in consideration of the loss of the torque consumed for motoring engine 150 to change the rotation speed. Here, in the present embodiment, the reaction torque is calculated by a different method according to the running state of the vehicle.

The CPU determines whether or not the vehicle is stopped (step S206), whether or not the start or stop of the engine 150 is instructed (step S208), and whether the engine speed Ne is equal to or lower than a predetermined speed Nlim. (Step S210). If at least one of these conditions is not satisfied, the reaction torque step is calculated based on the rate of change in the engine speed (step S212). If all of the above conditions are satisfied, a reaction torque step is calculated based on the engine torque (step S214).

The calculation method of each reaction force torque step is as follows. Here, the reaction torque step is
The torque acting between the gears of the planetary gear 120 affects the ring gear 122. In the equations (3) to (6) shown above, the second term “Ta / (1+) on the right side in the equation (5) that gives the rotation state of the ring gear 122.
ρ) ”corresponds to the reaction torque step. Since the gear ratio ρ is known, if the torque Ta is obtained, the reaction torque st
ep is calculated.

First, a method of calculating the torque based on the change in the engine speed will be described. Generally, the angular acceleration of the axle, that is, the rate of change of the rotational speed, is so small that it can be ignored compared to the angular accelerations of the motor MG1 and the engine. Therefore, βr = 0 can be set in the above-described equation (6).
The following equation (7) can be obtained. βc = ρβs / (1 + ρ) (7)

By solving the above equations (3), (4) and (7) as simultaneous equations using Tc, Ta and βs as unknowns, the torque Ta can be obtained, and the reaction force torque ste
p, that is, “Ta / (1 + ρ)” can be obtained as in the following equation (8). step = {− Ts + (1 + ρ) Is · βc} / ρ (8)

In the right side of the equation (8), Ts is the torque of the sun gear 121, and is therefore equal to the torque command value T1 * of the motor MG1. Is is an inertia coefficient of the sun gear 121 and the motor MG1 and is known. βc is the angular acceleration of the planetary carrier 124, and is equal to the rate of change in the rotation speed of the engine 150 input in step S204. Therefore, by substituting these quantities into equation (8), the reaction torque step can be obtained.

Next, when calculating the reaction force torque step based on the torque of the engine 150, the equations (3), (4) and (7) shown above should be replaced by simultaneous equations using βc, Ta, and βs as unknowns. , The torque Ta can be obtained, and the reaction torque step can be obtained as in the following equation (9). step = {− ρ · Ic · Ts + (1 + ρ) Is · Tc} / K (9) where K = ρ ＾ 2 · Ic + (1 + ρ) ＾ 2 · Is. Note that “＾” means a power operator.

In the right side of the equation (9), Ts is the torque of the sun gear 121, and is therefore equal to the torque command value T1 * of the motor MG1. Is is an inertia coefficient of the sun gear 121 and the motor MG1 and is known. Ic is an inertia coefficient of the planetary carrier 124 and the engine 150 and is known. Tc is the torque of the planetary carrier 124. In this embodiment, when starting or stopping the engine 150, that is, when the engine 150 is not operating independently, the calculation of the reaction torque step based on the engine torque in step S214 is executed. Therefore, Tc is equal to the rotational resistance required when motoring engine 150 with external force. This rotational resistance is mainly due to the frictional force of the engine 150,
In a region where the number of revolutions of the engine 50 is relatively low, it takes a substantially constant value according to the water temperature of the engine 150. Since the friction of the engine 150 has a considerable portion due to the viscosity of the lubricating oil acting between the piston and the cylinder, the rotational resistance changes according to the water temperature of the engine 150.

In the present embodiment, the rotational resistance is stored as a table in the ROM in the control unit 190 according to the water temperature of the engine 150. By referring to this table, it is possible to obtain a rotational resistance according to the water temperature of engine 150. Substituting these quantities into equation (9) gives
The reaction force torque step can be calculated. Of course, a constant value may be taken regardless of the water temperature of the engine 150. The predetermined rotational speed Nlim in step S210 is an upper limit value at which the rotational resistance of the engine 150 can be regarded as substantially constant, and
Is set in the range of the lower limit value at which the rotation speed of the motor can be detected with sufficient accuracy. In this embodiment, the predetermined rotation speed Nlim is set to 150 r.
pm.

Next, the CPU sets the target axle torque Td *,
And the difference between the reaction torque step and “Td * −s”.
The target torque T2 * of the motor MG2 is set by “step” (step S216). The CPU determines whether the absolute value of the target torque T2 * set in this way is larger than the rated torque Tlim of the motor MG2 (Step S).
218) If it exceeds this, the absolute value of the target torque T2 * is corrected to the rated torque Tlim (step S2).
20). Thus, the target torque setting process for the motor MG2 is completed, and the CPU returns to the torque control routine.

According to the operating points set in this way, the CPU sets the motors MG1 and MG2 and the engine 15
0 is controlled (step S210 in FIG. 3). In the control of the motors MG1 and MG2, a voltage to be applied to the three-phase coil of each motor is set according to the set target rotation speed and target torque, and a drive circuit 191 and a drive circuit 191 are set according to a deviation from the applied voltage at the present time. The switching of the transistor 192 is performed. For how to control the synchronous motor,
Since it is well known, detailed description is omitted here.

The control processing for operating the engine 150 at the set operation point is well known, and therefore the description thereof is omitted here. However, actually the engine 1
It is the EFIECU 170 that performs the control of 50. Therefore, in the process in step S700 in the torque control routine, the control unit 190 sends the EFIECU 170
A process for transmitting necessary information such as the operating point of the engine 150 is performed. By transmitting such information, the CPU of the control unit 190 indirectly causes the engine 150
Control the operation of By the above processing, the hybrid vehicle of the present embodiment applies appropriate power to the axle 1 according to the running state.
12 to output the vehicle.

According to the hybrid vehicle of the present embodiment described above, the torque fluctuation when starting or stopping the engine 150 while the vehicle is stopped can be appropriately suppressed. FIG. 8 shows how the rotation speed of the engine 150 and the output torque to the axle of the hybrid vehicle of this embodiment vary. FIG. 8 shows a state from when the engine 150 is started while the vehicle is stopped to when the engine 150 is stopped. As shown in the upper part of FIG. 8, when the start of the engine 150 is started at the time T1, the rotation speed of the engine is rapidly increased by the motoring from the motor MG1, and is stabilized at the rotation speed Ns at which the self-sustaining operation is to be started. . When stop of engine 150 is instructed at time T2, engine 150 stops fuel injection and ignition, and the number of revolutions is rapidly reduced to zero by negative torque output from motor MG1.

The lower part of FIG. 8 shows the state of the torque output to the axle in this process. As shown in regions As and Ast in FIG. 8, it can be seen that the fluctuation of the torque output to the axle is sufficiently suppressed even in the section where the engine 150 is started and stopped. FIG. 9 shows a state of change according to the conventional technique as a comparative example. 8, time T1
, The start of the engine 150 is started, and the stop is started at time T2. In the control according to the related art, as shown in the regions As1 and Ast1, it can be seen that the torque output to the axle when the engine 150 is started and stopped varies greatly.

Generally, in a low rotation speed region, the engine 1
The rotation of 50 is not stable. Therefore, FIG.
If the reaction force torque step is calculated based on the change in the engine speed shown in step S212 in the middle, the calculation accuracy of the reaction force torque step decreases. In the present embodiment, as shown in step S214 of FIG. 7, in a region where the number of revolutions of the engine 150 is low, the reaction torque step can be accurately calculated by using the rotation resistance. As a result, as shown in FIG. 8, it is possible to appropriately suppress the fluctuation of the torque output to the axle, and to suppress the vibration of the vehicle at the time of starting and stopping the engine. In the present embodiment, the vibration can be suppressed while the vehicle occupant is susceptible to sensitively detecting the vibration of the vehicle, so that the riding comfort of the hybrid vehicle can be greatly improved. Of course, the control based on the rotational resistance of the engine may be executed not only when the vehicle is stopped but also when the hybrid vehicle is running in the EV mode.

In the present embodiment, the method of calculating the reaction torque step is switched according to the rotation speed of the engine 150. As shown in step S210 in FIG. 7, in a region where the rotation speed of the engine 150 is low, the reaction force torque step is calculated based on the engine torque. To calculate the reaction force torque step. In a region where the engine speed can be detected with sufficient accuracy, the reaction torque step can be calculated with higher accuracy by using the rate of change of the engine speed. In this embodiment, the engine 15
By switching and using the method of calculating the reaction force torque step according to the rotation speed of 0, the reaction force torque step can be calculated with high accuracy in each rotation speed region, and the fluctuation of the torque output to the axle can be changed. Can be appropriately suppressed.

As the configuration of the hybrid vehicle to which the present invention is applied, various configurations other than the configuration shown in FIG. 1 are possible. For example, the present invention may be applied to a hybrid vehicle in which the coupling destination of motor MG2 can be switched between ring gear shaft 126 and crankshaft 156 using a mechanism such as a clutch and a spline. Of course, the present invention may be applied to a hybrid vehicle capable of switching the coupling to another axis.

In the hybrid vehicle of this embodiment, a power system including the engine 150 and the motors MG1 and MG2 is provided on the front axle 112. On the other hand, a configuration in which the motor MG2 is coupled to the rear axle as shown in FIG. 10 may be employed. As shown, the motor MG2 is coupled to the rear axle 112R instead of the front axle 112. In the hybrid vehicle having such a configuration, the power output from front axle 112 can be compensated for by motor MG2 such that the power output from both front axle 112 and rear axle 112R matches the required power. Therefore, the control method of the present invention can be applied to control of a hybrid vehicle. In the above embodiment, a hybrid vehicle using a planetary gear has been described as an example. However, another mechanism having the same effect may be applied.

The embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, and can be implemented in various forms without departing from the gist of the present invention. Of course. For example, in the above embodiment, various controls are executed by software, but these may be realized by hardware. When the vehicle is not stopped, the reaction torque may be calculated from the static torque balance in the planetary gear without considering the torque loss.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of a hybrid vehicle as an embodiment of the present invention.

FIG. 2 is a schematic diagram of a planetary gear.

FIG. 3 is a flowchart of a torque control routine.

FIG. 4 is a flowchart of a running state determination processing routine.

FIG. 5 is a graph illustrating a relationship between an engine operating point and an operating efficiency.

FIG. 6 is a graph showing the relationship between the engine speed and the operating efficiency when the required power is constant.

FIG. 7 is a flowchart of an MG2 target torque setting processing routine.

FIG. 8 is an explanatory diagram showing fluctuations in rotation speed and torque at the time of engine start.

FIG. 9 is an explanatory diagram showing fluctuations in the number of revolutions and the torque at the time of starting the engine in the prior art.

FIG. 10 is an explanatory diagram showing a modified configuration example of the hybrid vehicle of the embodiment.

[Explanation of symbols]

 112, 112R ... axles 116R, 116L ... wheels 119 ... case 120 ... planetary gear 121 ... sun gear 122 ... ring gear 123 ... planetary pinion gear 124 ... planetary carrier 125 ... sun gear shaft 126 ... ring gear shaft 127 ... planetary carrier shaft 129 ... chain belt 130 ... damper 132 ... rotor 133 ... stator 142 ... rotor 143 ... stator 144 ... sensor 149 ... battery 150 ... engine 156 ... crankshaft 158 ... engine water temperature sensor 165 ... accelerator pedal position sensor 167 ... shift position sensor 190 ... control units 191, 192 ... drive Circuit 194: Battery MG1, MG2: Motor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) F02D 29/02 321 B60K 9/00 Z F term (reference) 3D039 AA01 AA04 AB27 AC39 AC64 AC78 AD53 3G093 AA05 AA07 AA16 BA02 BA21 BA22 CA01 DA01 DA04 DA05 DA06 DA14 DB00 DB06 DB11 EB00 EC02 FA10 FA11 5H115 PG04 PI16 PI29 PI30 PO17 PU10 PU24 PU25 PV09 PV23 QA01 QN03 QN12 RB08 RE05 SE04 SE05 TB01 TE02 TE08 TI02 TO21 TO30

Claims (8)

[Claims] An engine and a first motor are provided on each of the rotating shafts of a power distribution device in which the rotating condition of the remaining rotating shaft is uniquely determined according to the rotating condition of two of the three rotating shafts.
A hybrid vehicle in which a motor is coupled to an axle, and a second motor is coupled to the axle, and input means for inputting a required torque to be output from the drive shaft; and for starting or stopping the engine. First target torque setting means for setting the motoring torque as a target torque of the first electric motor; and a reaction torque output to the axle by the first electric motor when adding the motoring torque. Estimating means for estimating based on the motoring torque and the rotational resistance of the engine; and estimating the second based on the required torque and the reaction torque.
A hybrid vehicle comprising: a target torque setting unit that sets a target torque of the electric motor; and a control unit that controls the first electric motor and the second electric motor to output respective target torques. 2. The hybrid vehicle according to claim 1, wherein said estimating means is a means for performing said estimation with said rotation resistance being a constant value when the rotation state of said engine is within a predetermined range. 3. The hybrid vehicle according to claim 1, further comprising: a temperature detecting unit that detects a temperature of the lubricating oil of the engine; and a storing unit that stores a relationship between the temperature and the rotational resistance. The hybrid vehicle, wherein the estimating unit is a unit that performs the estimation by using the rotational resistance obtained according to the temperature by referring to the storage unit. 4. The hybrid vehicle according to claim 1, further comprising a detection unit that detects a rotation speed of the engine, wherein the estimation unit is configured to detect the rotation speed of the engine only when the rotation speed is equal to or less than a predetermined value. A hybrid vehicle that is means for performing estimation based on motoring torque and rotational resistance. 5. The hybrid vehicle according to claim 4, wherein the estimating unit is configured to determine whether the rotation speed of the engine is greater than a predetermined value based on the motoring torque and a rate of change of the rotation speed. A hybrid vehicle for estimating the reaction torque. 6. The hybrid vehicle according to claim 1, further comprising: a determination unit configured to determine whether the vehicle is stopped, wherein the estimation unit determines whether or not the vehicle is stopped. A hybrid vehicle that is means for performing estimation based on the motoring torque and the rotational resistance. 7. The hybrid vehicle according to claim 1, wherein the axle to which the power distribution device is coupled and the axle to which the second electric motor is coupled are different axles and are coupled to the respective axles. Output power from the wheel
A hybrid vehicle that can be driven by wheels. 8. A power distribution device in which the rotation states of the remaining rotation axes are uniquely determined according to the rotation states of two of the three rotation axes, an engine and a first rotation shaft.
A motor and an axle, and a second motor is connected to the axle.
(A) inputting a required torque to be output from the drive shaft; and (b) applying a motoring torque for starting or stopping the engine from the first electric motor to the first motor.
Setting as the target torque of the electric motor of (c);
Estimating a reaction torque output from the first electric motor to the axle when the motoring torque is added, based on the motoring torque and the rotational resistance of the engine; and (d) the required torque. Setting the target torque of the second electric motor in consideration of the reaction torque; and (e) outputting the target torque by controlling the first electric motor and the second electric motor, respectively. A method for controlling a hybrid vehicle provided.