Method and system for controlling the torque of a hybrid vehicle with two motors

Abstract

Method for controlling a torque of a hybrid vehicle, which is equipped with a first motor (30) which controls the drive speed and a second motor (40) for compensating the drive torque and generating the required torque, wherein the method comprises the steps: Setting a target power output from a battery (50) based on vehicle speed, required torque and state of charge (SOC); Calculating a target torque of the first motor (30), a target torque of the second motor (40), a target torque of a drive (10), and a target speed of the drive (10) in a steady state, based on the vehicle speed, the required torque, and the target power of the battery (50); Calculating the torque of the first motor (30) in a transition state from the target torque of the second motor (40) in the steady state and the rotational speeds of the first and second motors (30, 40); and Calculating the torque of the second motor (40) in the transition state from the torque of the first motor (30) in the transition state and the rotational speeds of the first and second motors (30, 40).

Description

BACKGROUND OF THE INVENTION(a) Field of technology

[0001] The present invention relates to a method and system for controlling the torque of a hybrid vehicle. More precisely, the present invention relates to a method and system for controlling the torque of a hybrid vehicle, which calculates the power and torque of each motor when the hybrid vehicle, which is equipped with two motors, is operating in a transitional state. (b) Description of the associated technology

[0002] Generally, a hybrid vehicle is a vehicle that uses a drive system and an engine as a power source. While a hybrid vehicle can be equipped with a single engine and drive system, hybrid vehicles with two engines and a drive system are becoming increasingly popular in today's markets. In this case, a first engine is used to control the drive speed, and a second engine is used to compensate for the drive torque in accordance with the drive speed controlled by the first engine and to generate the required torque.

[0003] A control section of the hybrid vehicle sets target drive points for the drivetrain and the first and second motors using the vehicle speed, demand torque, and state of charge (SOC). However, these target drive points for the drivetrain and each motor are set under the assumption that the hybrid vehicle is operating in a steady state. Therefore, the actual drive points of the drivetrain and each motor may differ from the target drive points, and logic for setting the drive points of the drivetrain and each motor in a transitional state may be required when a hybrid vehicle is operating in a transitional state.

[0004] To determine the drive points of each motor in a transition state, a priority sequence is necessary. This means that if the drive points of two motors are determined simultaneously in a transition state, a significant error can occur. Therefore, after the drive point of one motor has been determined, the drive point of the other motor is determined using only the drive point of the first motor.

[0005] From DE 11 2005 001 279 T5, a power output device is known in this context, which delivers power to a drive shaft and has the following features: an internal combustion engine; a power conversion mechanism that converts at least part of the output power of the internal combustion engine into electrical power; an electric motor that delivers power to the drive shaft; an accumulator unit that transmits electrical power to and from the power conversion mechanism and electric motor; an input-output limit setting module that sets at least either an input limit or an output limit of the accumulator unit, as a lower and upper limit of a permissible electrical power range that is input to and output from the accumulator unit, based on whether the internal combustion engine is operating or stationary;a power requirement specification module that specifies a power requirement to be delivered to the drive shaft; and a control module that controls the internal combustion engine, the power conversion mechanism, and the electric motor to deliver a target power to the drive shaft in accordance with the specified power requirement, while adhering to the input and output limits of the accumulator unit.

[0006] DE 103 33 931 A1 discloses a method for controlling an electromechanically power-splitting hybrid drive of a motor vehicle with an internal combustion engine and two electric machines coupled by a transmission, as well as an electromechanically power-splitting hybrid drive for a motor vehicle.It is proposed that, based on the coupling conditions of the transmission, target speeds and target torques are calculated for the internal combustion engine and the two electric machines, that the respective target speeds are compared with the corresponding actual speeds of the internal combustion engine and the electric machines, and that in the event of a control deviation between one of the actual speeds and the corresponding target speed, one or more additional torques are calculated based on the control deviation, which are taken into account in the torque control of the internal combustion engine and the two electric machines in addition to the target torque(s) calculated by the control system.

[0007] Finally, JP 2009-143315A shows a system for controlling the torque of a hybrid vehicle, comprising: a drive unit; a first motor for controlling the drive speed; a second motor which compensates for the drive torque and generates a demand torque; and a control section which controls the drive unit, the first motor, and the second motor, wherein the control section calculates a torque of the first motor in a transition state using the target torque of the second motor in a steady state, and calculates a torque of the second motor in the transition state using the torque of the first motor in the transition state. To calculate the temporary torque Tmltmp, the temporary torque tm2tmp is required.

[0008] The above information disclosed in this section to describe the background is intended only to facilitate understanding of the background of the invention and may therefore contain information that does not constitute prior art already known to the person skilled in the art in this country. OVERVIEW OF THE INVENTION

[0009] The present invention was made with the aim of providing a method and a system for controlling the torque of a hybrid vehicle, which has advantages in determining the power and torque of each motor in a transitional state.

[0010] It is an object of the present disclosure to provide a method and a system for controlling the torque of a hybrid vehicle, wherein the power and torque of a first motor are determined for controlling the drive speed, and the power and torque of a second motor are determined for compensating the drive torque and generating the required torque using the power and torque of the first motor.

[0011] The problem is solved by a method with the features of claim 1 and a system with the features of claim 7. Advantageous further developments are found in the dependent claims.

[0012] A method for controlling the torque of a hybrid vehicle according to an exemplary embodiment of the present invention can determine the torque and power of each motor in the hybrid vehicle, which are provided by a first motor that controls the drive speed and a second motor for compensating the drive torque and generating the required torque.The procedure may include the following steps: defining a target power output from a battery, based on a vehicle speed, a demand torque, and a state of charge (SOC); calculating a target torque of the first motor, a target torque of the second motor, a target torque of a drive, and a target drive speed in a steady state, based on the vehicle speed, the demand torque, and the target power output of the battery; calculating a torque of the first motor in a transition state from the target torque of the second motor in the steady state and the speeds of the first and second motors; and calculating a torque of the second motor in the transition state from the torque of the first motor in the transition state and the speeds of the first and second motors.

[0013] The calculation of the torque of the first motor in the transition state can include the following steps: calculating the target power of the second motor in the steady state from the target torque of the second motor in the steady state and the speed of the second motor; calculating the maximum power of the first motor in the transition state from the target power of the second motor in the steady state and a power limit from a power source; and calculating a maximum torque of the first motor in the transition state from the maximum power of the first motor in the transition state and the speed of the first motor.

[0014] The calculation of the torque of the first motor in the transition state can also include the following steps: calculating the target torque of the first motor in the transition state, based on the target speed of the drive in the steady state and the speeds of the first and second motors; and determining the torque of the first motor in the transition state by comparing the maximum torque of the first motor and the target torque of the first motor in the transition state.

[0015] The calculation of the torque of the second motor in the transition state can also include the following steps: calculating the power of the first motor in the transition state from the torque of the first motor in the transition state and the speed of the first motor; calculating the maximum power of the second motor in the transition state from the power of the first motor in the transition state and the power limit of the power source; and calculating the maximum torque of the second motor in the transition state from the maximum power of the first motor in the transition state and the speed of the second motor.

[0016] The calculation of the torque of the second motor in the transition state can further include the following steps: calculating the target torque of the second motor in the transition state, based on the required torque and the torque of the first motor in the transition state; and determining the torque of the second motor in the transition state by comparing the maximum torque of the second motor with the target torque of the second motor in the transition state. The power output of the first motor in the transition state can be filtered to calculate the maximum power output of the second motor in the transition state.

[0017] A system for controlling the torque of a hybrid vehicle according to an exemplary embodiment of the present invention may comprise: a drive; a first motor for controlling the drive speed; a second motor which compensates for the drive torque and generates a demand torque; and a control section which controls the drive, the first motor, and the second motor. In particular, the control section calculates the torque of the first motor in a transition state using the target torque of the second motor in a steady state and the speeds of the first and second motors, and calculates the torque of the second motor in the transition state using the torque of the first motor in the transition state and the speeds of the first and second motors.

[0018] The control section can calculate the target power of the second motor in the transition state using the target torque of the second motor in the steady state and the speed of the second motor. The maximum power of the first motor in the transition state is then calculated using the target power of the second motor in the steady state and the power limit of a power source. Furthermore, the maximum torque of the first motor in the transition state is calculated using the maximum power of the first motor in the transition state and the speed of the first motor.

[0019] The control section can calculate the target torque of the first motor in the transition state, based on the target speed of the drive in the steady state and the speeds of the first and second motors, and can determine the torque of the first motor in the transition state by comparing the maximum torque of the first motor in the transition state with the target torque of the first motor.

[0020] The control section can also calculate the power output of the first motor in the transition state using its torque and rotational speed. Then, the maximum power output of the second motor in the transition state is calculated using the power output of the first motor and the power limit of the power source. The maximum torque of the second motor in the transition state is calculated using its maximum power output and rotational speed.

[0021] The control section can calculate the target torque of the second motor in the transition state, based on the required torque and the torque of the first motor in the transition state. Then, the control section can determine the torque of the second motor in the transition state by comparing its maximum torque in the transition state with its target torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments thereof, which are illustrated by the accompanying drawings, which are shown below for illustrative purposes only and are therefore not intended to limit the present invention, and wherein: Fig. Figure 1 is a schematic diagram illustrating a transmission of a hybrid vehicle to which a method for controlling a torque according to an exemplary embodiment of the present invention can be applied. Fig. Figure 2 is a block diagram of a system for controlling the torque of a hybrid vehicle according to an exemplary embodiment of the present invention. Fig. Figure 3 is a flowchart of a method for controlling the torque of a hybrid vehicle according to an exemplary embodiment of the present invention. Fig. Figure 4 is a flowchart illustrating the calculation of the power and torque of the first motor according to an exemplary embodiment of the present invention. Fig. Figure 5 is a flowchart illustrating the calculation of the power and torque of the second motor according to an exemplary embodiment of the present invention.

[0023] It is understood that the attached drawings are not necessarily to scale and represent a somewhat simplified depiction of various preferred features illustrating the basic principles of the present invention. The specific design features of the present invention as disclosed herein, including, for example, certain dimensions, orientations, positions, and configurations, will be partly determined by the specific intended application and the environment in which it is used. In the figures, reference numerals refer to the same or equivalent parts of the present invention across multiple figures of the drawings. DETAILED DESCRIPTION OF EXECUTION FORMS

[0024] An exemplary embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0025] Fig. Figure 1 is a schematic diagram illustrating a transmission of a hybrid vehicle to which a method for controlling a torque according to an exemplary embodiment of the present invention can be applied. As shown in Fig. Figure 1 shows a transmission from a hybrid vehicle, to which a method for controlling a torque according to an exemplary embodiment of the present invention can be applied, using a drive 10 and a first and second engine 30 and 40 as a power source. The drive 10 generates power by burning, for example, fuel. Different types of drives, such as a gasoline engine, a diesel engine, or an LPI engine (liquid propane injection), can be used as the drive 10.

[0026] The power from the drive 10 is transmitted to a first and second planetary gear set PG1 and PG2 via an input shaft 12. The first planetary gear set PG1 comprises a first sun gear S1, a first planet carrier C1, and a first ring gear R1 as its rotating element. The first sun gear S1 can always be connected to the first motor 30, and the first planet carrier C1 can always be connected to the drive 10. Additionally, a first brake BK1 is connected between the first sun gear S1 and the first motor 30 to selectively stop the first motor 30 if desired.

[0027] The second planetary gear set PG2 comprises a second sun gear S2, a second planet carrier C2, and a second ring gear R2 as its rotating element. The first planet carrier C1 is optionally connected to the second ring gear R2 by means of a first clutch CL1, and the first ring gear R1 is directly connected to the second planet carrier C2. Additionally, the second sun gear S2 is optionally connected to the drive 10 by means of a second clutch CL2, while simultaneously being permanently connected to the second motor 40. The second ring gear R2 can optionally be stopped by a second brake BK2, and the second planet carrier C2 can be continuously connected to an output gear 20.

[0028] Operationally, the first motor 30 controls the input speed, which is fed to the first planetary gear carrier C1 via the first sun gear S1. The first planetary gear carrier C1 transmits the input speed to the output gear 20 via the first ring gear R1 and the second planetary gear carrier C2. The speed of the first motor is combined with the input speed and the target speed (i.e., controlled by the speed of the first motor and the input speed) which is transmitted to the output gear. In this way, the input speed is controlled in accordance with the speed of the first motor and the target speed when the speed of the first motor is determined.

[0029] The second motor 40 compensates for the drive torque, which is applied via the first planetary gear carrier C1, and the drive torque, which is optionally applied via the second sun gear S2, so that the required torque is delivered via the output gear 20. That is, the second motor 40 compensates for the drive torque in order to generate the required torque accordingly.

[0030] A battery 50 provides electricity / power to the first and second motors 30 and 40 while operating in a first mode and being charged by electricity generated at the first and second motors 30 and 40 under a predetermined driving condition in a second mode, in order to maintain the battery charge above a certain state.

[0031] Fig. Figure 2 is a block diagram of a system for controlling the torque of a hybrid vehicle according to an exemplary embodiment of the present invention. As shown in Fig. Figure 2 shows a system for controlling the torque of a hybrid vehicle according to an exemplary embodiment of the present invention comprising a vehicle speed detector 62, a speed detector of the first motor 64, a speed detector of the second motor 66, a SOC detector 68, a control section 60, and the first and second motors 30 and 40. In addition, a plurality of sensors for detecting the operation of the drive 10, the transmission, the first and second motors 30 and 40, and the battery 50 may also be included.

[0032] In this embodiment, the vehicle speed detector 62 detects the current vehicle speed and sends a corresponding signal to the control unit 60. The speed detector of the first motor 64 detects the current rotational speed of the first motor 30 and sends a corresponding signal to the control unit 60. The speed detector of the second motor 66 detects the current rotational speed of the second motor 40 and sends a corresponding signal to the control unit 60. The state-of-charge (SOC) detector 68 detects the state of charge (SOC) of the battery 50 and sends a corresponding signal to the control unit 60.

[0033] Control section 60 defines the drive points of the drive unit and each motor in a steady state, based on the vehicle speed, the rotational speeds of the first and second motors 30 and 40, and the state of charge (SOC) of the battery 50, and defines the drive points of each motor in a transitional state. Control section 60 controls the operations of the drive unit 10, the first motor 30, and the second motor 40 in accordance with the defined drive points.

[0034] Below, a method for controlling the torque of a hybrid vehicle according to an exemplary embodiment of the present invention is described in detail with reference to Fig. 3 to Fig. 5 will be described.

[0035] Fig. Figure 3 is a flowchart of a method for controlling the torque of a hybrid vehicle according to an exemplary embodiment of the present invention. Fig. Figure 4 is a flowchart illustrating the calculation of the power and torque of the first motor according to an exemplary embodiment of the present invention, and Fig. Figure 5 is a flowchart illustrating the calculation of the power and torque of the second motor according to an exemplary embodiment of the present invention.

[0036] As in Fig. Figure 3 shows a method for controlling a torque of a hybrid vehicle according to an exemplary embodiment of the present invention comprising setting a target power of the battery in a step S100, calculating drive points of the drive 10 and of each motor 30 and 40 in the steady state in a step S200, and calculating drive points of each motor 30 and 40 in the transition state in a step S300.

[0037] The control section 60 calculates the required torque based on the current vehicle speed, the position of an accelerator pedal, and the drive speed in step S112. It receives the current vehicle speed from the vehicle speed detector 62 in step S114 and the state of charge (SOC) of battery 50 from the SOC detector 68 in step S116. Additionally, the control section 60 receives a charge / discharge limit in step S118 and limiting conditions for drive 10 and each motor 30 and 40 in step S120. The charge / discharge limit and the limiting conditions for drive 10 and each motor 30 and 40 can be stored in the control section 60 for later use, for example, in RAM.

[0038] The control section 60 then determines the power of the battery 50 from the vehicle speed, the required torque, and the charge / discharge limit in one step S121, and determines the target power of the battery 50 by comparing the power of the battery 50 with the charge / discharge limit in one step S122.

[0039] The control section 60 then determines the target drive point in the steady state by using the required torque, the vehicle speed, the target power of the battery 50, and the limiting conditions of the drive 10 and each motor 30 and 40 in a step S202. That is, the target torque of the first motor 30 in the steady state is calculated in a step S204, the target torque of the second motor 40 in the steady state is calculated in a step S206, the target torque of drive 10 in the steady state is calculated in a step S208, and the target speed of drive 10 in the steady state is calculated in a step S210.In addition, the control section 60 receives the rotational speed of the second motor 40 from the speed detector of the second motor 66 in a step S212, and receives the rotational speed of the first motor 30 from the speed detector of the first motor 64 in a step S214.

[0040] Next, the control section 60 calculates the target speed of the first motor 30 from the target speed of the drive 10 in the steady state and the speed of the second motor 40 in a step S216, and subtracts the speed of the first motor 30 from the target speed of the first motor 30 in a step S302.

[0041] Control section 60 calculates the target torque of the first motor 30 in the transition state using the difference between the target speed of the first motor 30 and the actual speed of the first motor 30 in step S304, and limits the torque of the first motor 30 by using the target torque of the first motor 30, the charge / discharge limit of the first motor 30 (determined by the charge / discharge limit of a power source (the battery 50)), the target power of the second motor 40 in the steady state, and the speed of the first motor 30 in step S310. Consequently, the torque of the first motor 30 in the transition state is calculated in step S312.

[0042] In addition, control section 60 calculates the target torque of the second motor 40 in the transition state by subtracting the torque of the first motor 30 in the transition state from the required torque in step S316. Furthermore, control section 60 limits the torque of the second motor 40 in step S320 by using the target torque of the second motor 40 in the transition state, the charge / discharge limit of the second motor 40, the power of the first motor in the transition state, and the speed of the second motor 40. Therefore, the torque of the second motor 40 in the transition state is calculated in step S322.

[0043] Referring now to Fig. 4, the processes for calculating the torque of the first motor 30 in the transition state will be described in detail.

[0044] The control section 60 calculates the target power of the second motor 40 in the steady state by multiplying the target torque of the second motor 40 in the steady state and the speed of the second motor 40 in a step S330, and multiplies a first gain by the target power of the second motor 40 in the steady state in a step S332.

[0045] Control section 60 calculates the maximum discharge power of the first motor 30 in the transition state from the discharge power limit of the first motor 30, the target power of the second motor 40 in the steady state, and the first gain in one step S334. Additionally, control section 60 calculates the maximum discharge torque of the first motor 30 in the transition state by using the maximum discharge power of the first motor 30 in the transition state and the rotational speed of the first motor 30 in one step S336. The maximum discharge torque can be calculated from a predetermined discharge efficiency map.

[0046] Similar to the calculation of the maximum discharge torque, the control section 60 calculates the maximum charging torque of the first motor 30 in the transition state in step S344. That is, the control section 60 calculates the maximum charging power of the first motor 30 in a transition state from the charging power limit of the first motor 30, the target power of the second motor 40 in the steady state, and the first gain in step S342, and calculates the maximum charging torque of the first motor 30 in the transition state using the maximum charging power of the first motor 30 in the transition state and the speed of the first motor 30 in step S344.

[0047] The control section 60 determines whether charging or discharging occurs by multiplying the target torque of the first motor 30 in the transition state by the speed of the first motor 30 in a step S338, and determines in a step S340 whether the maximum charging torque or the maximum discharging torque of the first motor 30 in the transition state is used, based on whether the sign is positive (+) or negative (-) in each case.

[0048] Control section 60 calculates the absolute value of the target torque of the first motor 30 in the transition state in step S346 and compares the maximum charging torque or the maximum discharging torque determined in step S340 with the absolute value of the target torque in step S348. Then, control section 60 calculates the torque of the first motor 30 in the transition state in step S312. In S348, a minimum value is selected. Since step S348 is performed without a sign, the sign is added in step S312, as shown in Fig. 4 shown.

[0049] Referring to Fig. 5, the processes for calculating the torque of the second motor 40 in the transition state will be described in detail.

[0050] The control section 60 calculates the power of the first motor 30 in the transition state from the torque of the first motor 30 in the transition state and the speed of the first motor 30 in a step S350, and filters the power of the first motor 30 in the transition state in a step S352 such that the torque of the second motor 40 in the transition state is not affected by fluctuations in the power of the first motor 30 in the transition state.

[0051] Control section 60 subtracts the filtered power of the first motor 30 in the transition state from the discharge power limit of the second motor 40 in step S354, and calculates the maximum discharge power of the second motor 40 in the transition state from the discharge power limit of the second motor (calculated from the charge / discharge limit of the power source (the battery 50)), the filtered power of the first motor 30 in the transition state, and a second gain in step S356. Additionally, control section 60 calculates the maximum discharge torque of the second motor 40 in the transition state using the maximum discharge power of the second motor 40 in the transition state and the rotational speed of the second motor 40 in step S358. The maximum discharge torque is calculated from the predetermined discharge efficiency map.

[0052] Similar to the calculation of the maximum discharge torque, the control section 60 calculates the maximum charging torque of the second motor 40 in the transition state in step S366. That is, the control section 60 calculates the maximum charging power of the second motor 40 in the transition state from the charging power limit of the second motor 40, the filtered power of the first motor 30 in the transition state, and the second gain in step S364, and calculates the maximum charging torque of the second motor 40 in the transition state using the maximum charging power of the second motor 40 in the transition state and the speed of the second motor 40 in step S366.

[0053] The control section 60 then determines whether charging or discharging occurs by multiplying the target torque of the second motor 40 in the transition state and the speed of the second motor 40 in a step S360, and determines in a step S362 whether the maximum charging torque or the minimum discharging torque of the second motor 40 in the transition state is used, based on whether the sign is positive (+) or negative (-) in each case.

[0054] Control section 60 calculates the absolute value of the target torque of the second motor 40 in the transition state in step S368 and compares the maximum charging torque or the maximum discharging torque determined in step S362 with the absolute value of the target torque in step S370, based on whether the sign is positive (+) or negative (-). Control section 60 then calculates the torque of the second motor 40 in the transition state in step S322.

[0055] Furthermore, the control mechanisms / sections of the present invention can be contained as a computer-readable data carrier on a computer-readable medium, which contains executable program instructions that are executed by a processor. Examples of the computer-readable medium include, but are not limited to, ROM, RAM, Compact Disc (CD)-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The computer-readable recording medium can also be distributed in computer systems connected to a network, so that the computer-readable data carriers are stored and executed in a distributed manner, e.g., wirelessly on a remote server.

[0056] As described above, the optimal torque of each motor in a transition state can be calculated according to an exemplary embodiment of the present invention, since the power and torque of a second motor, which generates the final required torque, are determined after the power and torque of a first motor, which controls the drive speed, have been determined.

[0057] In addition, fuel consumption can be improved and a SOC can be managed stably, as each engine and drive is controlled using the optimal torque of each engine.

Claims

[1] Method for controlling a torque of a hybrid vehicle which is equipped with a first motor (30) which controls the drive speed and a second motor (40) for compensating the drive torque and generating the required torque, wherein the method comprises the steps: Setting a target power output from a battery (50) based on vehicle speed, required torque and state of charge (SOC); Calculating a target torque of the first motor (30), a target torque of the second motor (40), a target torque of a drive (10), and a target speed of the drive (10) in a steady state, based on the vehicle speed, the required torque, and the target power of the battery (50); Calculating the torque of the first motor (30) in a transition state from the target torque of the second motor (40) in the steady state and the rotational speeds of the first and second motors (30, 40); and Calculating the torque of the second motor (40) in the transition state from the torque of the first motor (30) in the transition state and the rotational speeds of the first and second motors (30, 40). [2] Method according to claim 1, wherein the calculation of the torque of the first motor (30) in the transition state comprises the steps: Calculating a target power of the second motor (40) in the steady state from the target torque of the second motor (40) in the steady state and the speed of the second motor (40); Calculating a maximum power output of the first motor (30) in the transition state from the target power output of the second motor (40) in the steady state and a power limit of a power source; and Calculating a maximum torque of the first motor (30) in the transition state from the maximum power of the first motor (30) in the transition state and the speed of the first motor (30). [3] Method according to claim 2, wherein the calculation of the torque of the first motor (30) in the transition state further comprises the steps: Calculating the target torque of the first motor (30) in the transition state, based on the target speed of the drive (10) in the steady state and the respective speeds of the first and second motors (30, 40); and Determining the torque of the first motor (30) in the transition state by comparing the maximum torque of the first motor (30) and the target torque of the first motor (30) in the transition state. [4] Method according to claim 1, wherein the calculation of the torque of the second motor (40) in the transition state comprises the steps: Calculating the power of the first motor (30) in the transition state from the torque of the first motor (30) in the transition state and the speed of the first motor (30); Calculating a maximum power output of the second motor (40) in the transition state from the power output of the first motor (30) in the transition state and a power limit of the power source; and Calculating a maximum torque of the second motor (40) in the transition state from the maximum power of the first motor (30) in the transition state and the speed of the second motor (40). [5] Method according to claim 4, wherein the calculation of the torque of the second motor (40) in the transition state further comprises the steps: Calculating the target torque of the second motor (40) in the transition state, based on the required torque and the torque of the first motor (30) in the transition state; and Determining the torque of the second motor (40) in the transition state by comparing the maximum torque of the second motor and the target torque of the second motor (40) in the transition state. [6] Method according to claim 5, wherein the power of the first motor (30) in the transition state is filtered to calculate the maximum power of the second motor (40) in the transition state. [7] System for controlling torque of a hybrid vehicle, comprising: a drive (10); a first motor (30) for controlling the drive speed; a second motor (40) which compensates for the drive torque and generates a demand torque; and a control section (60) which controls the drive (10), the first motor (30) and the second motor (40), wherein the control section (60) calculates a torque of the first motor (30) in a transition state using the set torque of the second motor (40) in a steady state and the speeds of the first and second motors (30, 40), and calculates a torque of the second motor (40) in the transition state using the torque of the first motor (30) in the transition state and the speeds of the first and second motors (30, 40). [8] System according to claim 7, wherein the control section (60) calculates the target power of the second motor (40) in the transition state using the target torque of the second motor (40) in the steady state and the speed of the second motor (40), and calculates the maximum power of the first motor (30) in the transition state using the target power of the second motor (40) in the steady state and the power limit of a power source, and calculates the maximum torque of the first motor (30) in the transition state using the maximum power of the first motor (30) in the transition state and the speed of the first motor (30). [9] System according to claim 8, wherein the control section (60) calculates the target torque of the first motor (30) in the transition state, based on the target speed of the drive (10) in the steady state and the speeds of the first and second motors (30, 40), and determines the torque of the first motor (30) in the transition state by comparing the maximum torque of the first motor (30) in the transition state with the target torque of the first motor (30). [10] System according to claim 8, wherein the control section (60) calculates the power of the first motor in the transition state using the torque of the first motor (30) in the transition state and the speed of the first motor (30), calculates the maximum power of the second motor (40) in the transition state using the power of the first motor (30) in the transition state and the power limit of the power source, and calculates the maximum torque of the second motor (40) in the transition state using the maximum power of the second motor (40) in the transition state and the speed of the second motor (40). [11] System according to claim 10, wherein the control section (60) calculates the target torque of the second motor (40) in the transition state based on the required torque and the torque of the first motor (30) in the transition state, and determines the torque of the second motor (40) in the transition state by comparing the maximum torque of the second motor (40) in the transition state and the target torque of the second motor (40). [12] Non-volatile, computer-readable medium containing executable program instructions which are executed by a processor, with: Program instructions that define a target power output from a battery (50) based on a vehicle speed, a required torque, and a state of charge (SOC); Program instructions which calculate a target torque of the first motor (30), a target torque of the second motor (40), a target torque of a drive (10), and a target speed of the drive (10) in a steady state, based on the vehicle speed, the required torque, and the target power of the battery (50); Program instructions that calculate the torque of the first motor (30) in a transition state from the target torque of the second motor (40) in the steady state and the rotational speeds of the first and second motors (30, 40); and Program instructions which calculate a torque of the second motor (40) in the transition state from the torque of the first motor (30) in the transition state and the rotational speeds of the first and second motors (30, 40). [13] Non-volatile computer-readable medium according to claim 12, wherein the program instructions which calculate the torque of the first motor (30) in the transition state further comprise: Program instructions which calculate a target power of the second motor (40) in the steady state from the target torque of the second motor (40) in the steady state and the speed of the second motor (40); Program instructions that calculate a maximum power output of the first motor (30) in the transition state from the target power output of the second motor (40) in the steady state and the power limit of a power source; and Program instructions which calculate a maximum torque of the first motor (30) in the transition state from the maximum power of the first motor (30) in the transition state and the speed of the first motor (30). [14] Non-volatile computer-readable medium according to claim 13, wherein the program instructions which calculate the torque of the first motor (30) in the transition state further comprise: Program instructions that calculate the target torque of the first motor (30) in the transition state, based on the target speed of the drive (10) in the steady state and the speeds of the first and second motors (30, 40) respectively; and Program instructions that determine the torque of the first motor (30) in the transition state by comparing the maximum torque of the first motor (30) and the target torque of the first motor (30) in the transition state. [15] Non-volatile computer-readable medium according to claim 14, wherein the program instructions which calculate the torque of the second motor (40) in the transition state comprise: Program instructions that calculate the power of the first motor (30) in the transition state from the torque of the first motor (30) in the transition state and the speed of the first motor (30); Program instructions that calculate the maximum power of the second motor (40) in the transition state from the power of the first motor (30) in the transition state and the power limit of the power source; and Program instructions which calculate the maximum torque of the second motor (40) in the transition state from the maximum power of the second motor (40) in the transition state and the speed of the second motor (40). [16] Non-volatile computer-readable medium according to claim 15, wherein the program instructions which calculate the torque of the second motor (40) in the transition state further comprise: Program instructions that calculate the target torque of the second motor (40) in the transition state, based on the required torque and the torque of the first motor (30) in the transition state; and Program instructions that determine the torque of the second motor (40) in the transition state by comparing the maximum torque of the second motor (40) with the target torque of the first motor (30) in the transition state. [17] Non-volatile computer-readable medium according to claim 15, further comprising program instructions which filter the power of the first motor (30) in the transition state in order to calculate the maximum power of the second motor (40) in the transition state.

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