JP5938924B2 - Regenerative control device - Google Patents

Description

  The present invention relates to a regenerative control device that controls the rotational speed of a generator during regenerative power generation.

  Conventionally, as a technique for improving the fuel efficiency of a vehicle equipped with an engine and a generator, regenerative power generation is performed during vehicle deceleration, braking, coasting, etc., and the power generation load during normal driving is suppressed. Technology is known. In other words, electric power is generated by using the driving force transmitted from the driving wheel side, and the electric power can be stored by storing the electric power.

  For example, in hybrid electric vehicles that use both an engine and a motor generator to drive the vehicle, a technology has been developed that improves the vehicle's travel distance and acceleration by driving the motor generator using the recovered power. Has been. There is also a technology to reduce the power generation load acting on the engine by controlling connection / disconnection of the engine and alternator according to the running state even in a normal automobile equipped with only an engine as a vehicle drive source. To do. Thus, energy efficiency can be improved by recovering the surplus kinetic energy of the vehicle as electric energy.

  Incidentally, the amount of electric power generated by the generator by regenerative power generation changes according to the amount of energy loss in the engine. For example, when the engine brake is acting strongly during braking of the vehicle, the intake / exhaust loss (pumping loss) and mechanical loss (friction loss) of the engine are larger than when the engine brake is weak, and the power is generated by the generator. The amount of power to be reduced. That is, as a result of a part of the kinetic energy of the vehicle being converted into heat energy and lost, the electrical energy recovered by regenerative power generation is relatively reduced.

  Therefore, a technique for improving the power generation efficiency (power conversion efficiency) during regenerative power generation by controlling engine friction has been proposed. For example, Patent Document 1 discloses a technique for setting the gear stage of a transmission so that the efficiency of regenerative braking is maximized when the driving force required for the vehicle is negative (for example, during braking). In this technique, the rotational speed input to the engine from the wheel side is reduced by setting the gear stage of the transmission to the highest gear stage (the gear stage having the smallest gear ratio) during regenerative braking. It is stated that such control reduces engine friction loss and increases regenerative braking efficiency.

JP 2006-341848 A

However, the conventional technology does not consider the energy loss inside the generator. That is, “power generation efficiency” indicating how much the driving force input to the generator is converted into electric power is not taken into consideration, and the capacity of the generator is evaluated only by the amount of power generation. For this reason, as the amount of power generation increases, the proportion of energy lost as heat increases, and there is a problem that overall energy efficiency cannot be improved.
Further, since the amount of heat generated by power generation increases as the amount of power generation increases, the rotor inside the generator tends to have heat, and wear and deterioration tend to progress. Therefore, an expensive generator excellent in wear resistance must be prepared, or a structure for cooling the generator is required, and there is a problem that the product cost is likely to increase.

The energy loss at the generator not only affects the environmental performance and energy saving performance of the vehicle, but can also affect the controllability of the entire vehicle. That is, paying attention to the energy balance at the time of regenerative power generation of the vehicle, when the amount of energy consumption in the generator changes due to fluctuations in power generation efficiency, the amount of energy corresponding to the energy consumption is consumed by the engine or braking device.
For example, if the power generation efficiency of the generator increases, the energy consumed by the generator decreases with respect to the constant kinetic energy given from the drive wheel side, and the energy acting on the engine increases accordingly. As a result, the amount of heat generated in the engine increases, and the strength of the engine brake may change. Also, the kinetic energy that could not be consumed by the engine is borne by the braking device and the automatic braking device. That is, the magnitude of energy to be borne by the braking device or the automatic braking device varies depending on the power generation efficiency of the generator.
Therefore, unless the power generation efficiency during regenerative power generation is taken into account, the braking force and heat generation amount of the entire vehicle cannot be accurately grasped, and the overall control stability cannot be improved.

One of the purposes of this case was devised in view of the above-mentioned problems, taking into account the loss inside the generator, and improving the vehicle control stability while improving the energy efficiency of regenerative power generation. That is.
It should be noted that the present invention is not limited to the above-described object, and it is possible to obtain operations and effects that are derived from the respective configurations shown in the embodiments for carrying out the invention that will be described later and that cannot be obtained by the conventional technology. It can be positioned as a purpose.

(1) A regenerative control device disclosed herein is connected to a power transmission path of an engine and performs regenerative power generation with torque transmitted from drive wheels, and is interposed between the generator and the drive wheels. A transmission.
In addition, a rotation speed calculating means for calculating the rotation speed of the generator that generates power at a predetermined efficiency or higher with the torque input to the generator based on the power generation efficiency characteristics of the generator. Furthermore, a gear ratio control means for determining a gear ratio of the transmission at the time of regenerative power generation of the generator based on the rotation speed calculated by the rotation speed calculation means.
The rotation speed calculation means calculates a rotation speed of the generator that causes a power generation efficiency to be equal to or lower than a second predetermined efficiency higher than the predetermined efficiency by a torque input to the generator.

The power generation efficiency characteristic of the generator is a characteristic of the power generation efficiency of the generator with respect to the torque input to the generator and the rotational speed of the generator. The power generation efficiency means a ratio of power generation energy to energy input to the generator. Further, the generated energy is equal to energy lost due to friction loss inside the generator (for example, energy converted into heat) subtracted from energy input to the generator.
An upper limit value may be provided for setting the power generation efficiency. In this case, the maximum power generation efficiency means the maximum power generation efficiency in a range equal to or lower than the second predetermined efficiency. That is, the following optimum efficiency rotational speed is the rotational speed of the generator at which the power generation efficiency becomes the second predetermined efficiency.

The transmission ratio control means controls the transmission ratio so that the rotational speed transmitted from the transmission ratio to the generator side becomes the rotational speed of the generator calculated by the rotational speed calculation means. It is preferable.
The power generation efficiency decreases as the friction loss increases, and increases as the friction loss decreases. Therefore, the rotational speed calculation means is configured so that the friction loss generated in the generator is less than a predetermined amount based on the friction loss characteristic (friction characteristic) of the generator instead of the power generation efficiency characteristic of the generator. It is good also as a structure which calculates.

Incidentally, the rotational speed calculation means, based on the power generation efficiency characteristics of the generator, it is conceivable that the power generation efficiency in torque input to the generator computes the rotation speed of the generator with the maximum. The rotation speed (optimum efficiency rotation speed) of the generator that maximizes the power generation efficiency does not necessarily match the rotation speed (maximum output rotation speed) that maximizes the power generation amount (output) of the generator. Therefore, the optimum efficiency rotation speed is given priority when the maximum efficiency rotation speed and the maximum output rotation speed do not match.

( 2 ) Further, the generator has a rotating shaft directly connected to the rotating shaft of the engine, and the rotation speed calculation means is based on the power generation efficiency characteristic of the generator and the friction loss characteristic of the engine. It is preferable to calculate the rotational speed of the generator.
In this case, it is preferable that the rotation speed calculation means calculates the rotation speed of the generator that minimizes the sum of the friction loss inside the generator and the friction loss on the engine side.

( 3 ) Alternatively, a second transmission interposed between the engine and the drive wheel or the generator may be provided. In this case, the generator has a rotational shaft that is not directly connected to the rotational shaft of the engine, and the rotational speed calculation means is input to the generator based on the power generation efficiency characteristic of the generator. Based on the first engine speed calculation means for calculating the first engine speed of the generator, the power generation efficiency of which is equal to or higher than the predetermined efficiency with the torque to be generated, and the friction loss characteristic of the engine, the friction loss of the engine becomes a predetermined amount or less It is preferable to have a second rotation speed calculation means for calculating the second rotation speed of the engine.

  Further, the transmission ratio control means controls the transmission ratio of the transmission based on the first rotation speed calculated by the first rotation speed calculation means, and the second rotation speed. It is preferable to have second speed ratio control means for controlling the speed ratio of the second transmission based on the second rotational speed calculated by the calculating means.

According to the disclosed regenerative control device, the gear ratio is controlled based on the number of revolutions calculated from the power generation efficiency characteristics, so that friction loss of power generation efficiency can be reduced and unnecessary heat generation in the generator is suppressed. can do. Further, the engine temperature can be prevented from lowering by making the engine bear the energy corresponding to the heat loss of the generator. Further, by driving the generator at a rotational speed with a small friction, it is possible to suppress the progress of wear and deterioration of the rotor inside the generator. Furthermore, since the fluctuation range of the rotational speed of the generator is limited to a range where the power generation efficiency is high, the rotational speed fluctuation during regenerative power generation can be reduced, and the power generation amount and the regenerative braking force can be stabilized. .
As a result, the overall control stability of the vehicle during regenerative power generation can be improved while continuing power generation with guaranteed power generation efficiency.

It is a schematic diagram which illustrates the block configuration of a regeneration control apparatus, and the vehicle structure used as application object. It is a graph which illustrates the relationship between the friction loss torque of an engine, and rotation speed It is a graph which illustrates the relationship between the friction loss torque of a motor generator, and rotation speed. It is a graph which illustrates the power generation efficiency characteristic of a motor generator, (a) and (c) show the relation to the drive torque and the number of rotations of the power generation efficiency in which friction loss of only the motor generator was considered, and (b) is the motor generator. The relationship between the power generation efficiency in consideration of the friction loss of the engine and the drive torque and the rotational speed is shown. It is a flowchart which illustrates the control procedure in a regeneration control apparatus. It is a schematic diagram which illustrates the block structure of the regeneration control apparatus as a modification, and the vehicle structure used as application object.

  The regenerative control device will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit of the present embodiment, and can be selected or combined as necessary.

[1. Device configuration]
[1-1. Drive system]
The regeneration control device of this embodiment is applied to the vehicle 20 shown in FIG. The vehicle 20 is a series / parallel hybrid hybrid electric vehicle that can run using both the engine 1 and the motor generator 3 (generator) alone as drive sources. The drive system of the vehicle 20 includes an engine 1, a clutch 2, a motor generator 3, an automatic transmission 4, and a drive wheel 5 connected in series. The drive wheel 5 can be driven with output only at least one of the engine 1 and the motor generator 3. Further, for example, it is possible to transmit power only between the engine 1 and the motor generator 3 by cutting off the power transmission path in the automatic transmission 4.

The engine 1 is configured as a general internal combustion engine (gasoline engine, diesel engine) that burns gasoline or light oil. The clutch 2 is a linkage that is interposed between the output shaft of the engine 1 and the drive shaft of the motor generator 3 and connects and disconnects the power transmission regardless of the power transmission direction.
The automatic transmission 4 (transmission) is a power transmission device for decelerating and transmitting the output rotational speed transmitted from the engine 1 and the motor generator 3 side to the drive wheels 5. On the other hand, when the vehicle is coasting or decelerating, it functions to transmit the power on the drive wheel 5 side to the engine 1 and the motor generator 3.

The specific structure of the automatic transmission 4 is arbitrary, and includes, for example, a planetary gear mechanism, a CVT (Continuously Variable Transmission) mechanism, a clutch / brake mechanism, etc. (not shown). The transmission ratio (reduction ratio) of the automatic transmission 4 is controlled by an electronic control unit 9 described later.
Note that the planetary gear mechanism is a transmission having a structure in which a sun gear (sun gear) and a plurality of planetary gears (planetary gears) are provided inside an outer ring gear (outer gear), and the central axes of the planetary gears are connected by a planet carrier. Mechanism. In the case of the automatic transmission 4 provided with this planetary gear mechanism, a plurality of types of gear ratios are realized by limiting the rotational operations of the three rotating elements of the outer ring gear, the sun gear, and the planet carrier.

The CVT mechanism is a speed change mechanism that can continuously change the ratio between the input rotation speed and the output rotation speed. In the case of the automatic transmission 4 having a belt-type CVT mechanism that transmits power via a belt suspended on the conical surfaces of two pulleys, the belt is continuously moved by moving the suspension position of the belt with respect to the conical surface of the pulley. The gear ratio is realized.
The clutch / brake mechanism is a mechanism for connecting / disconnecting power transmission by controlling the magnitude of the frictional force generated between opposing frictional engagement elements or by restricting the movement of the frictional engagement elements. For example, at the time of shifting by the planetary gear mechanism or when the vehicle is stopped, the clutch / brake mechanism is controlled to be in a disconnected / fixed state, and transmission of the driving force to the drive wheel 5 side is cut off.

  The motor generator 3 is a motor generator that has both a function as a motor (electric motor) and a function as a generator (generator). The rotating shaft of the motor generator 3 is connected to the rotating shaft on the output side of the clutch 2. In FIG. 1, an example in which the rotation shaft of the motor generator 3 is coaxially connected to the drive shaft of the engine 1 via the clutch 2 is illustrated, but the motor generator 3 is connected to the drive wheel 5 in parallel with the engine 1. Also good.

A battery 7 is connected to the motor generator 3 via an inverter 6. The battery 7 is a power storage device serving as a main power source for power, and the inverter 6 is a power conversion device that converts DC power into AC power or converts AC power into DC power.
When the motor generator 3 functions as a generator, regenerative power generation using the torque input from the engine 1 and the driving force input from the driving wheel side is performed, and the electric power generated by the motor generator 3 is supplied to the battery via the inverter 6. 7 is charged. Regenerative power generation is performed, for example, during coasting when the accelerator pedal is not depressed or during deceleration when the brake pedal is depressed.
Further, when the motor generator 3 functions as a motor, the motor generator 3 rotates using the electric power of the battery 7, adds the motor driving force to the driving force of the engine 1, and outputs it to the driving wheel side. The addition of the motor driving force is performed, for example, when the vehicle 20 is started or when the load acting on the engine 1 is high.

  The electric / power generation function of the motor generator 3 as described above is determined by the magnitude relationship between the power supplied from the inverter 6 to the motor generator 3 and the regenerative power from the motor generator 3 to the inverter 6. For example, when the driving force input from the driving wheel side is larger than the driving force generated by the motor generator 3 and the motor generator 3 is driven by the driving wheel, the regenerative power exceeds the supplied power, and the motor generator 3 Functions as a generator. On the other hand, in a state where the motor generator 3 gives a driving force to the driving wheel side, the regenerative power is lower than the supplied power, so that the motor generator 3 functions as a motor. The inverter 6 determines whether the motor generator 3 is functioning as a motor or a generator, and transmits the information to an electronic control unit 9 described later.

The battery 7 is, for example, an assembled battery in which a plurality of battery modules are accommodated in a case, and is configured to be able to input / output power (can be charged / discharged) with the motor generator 3. The battery 7 has a charge rate range (operation charge rate range) that can be used (operated) in advance. The operating charge rate range is, for example, a variation range of the amount of charge inside the battery determined by the durability of the battery 7, the output required by the electric device equipped with the battery 7, the request for operating the battery 7, etc. . The battery 7 mounted on a general electric vehicle or hybrid electric vehicle is charged and discharged so that the charging rate varies within the operating charging rate range.
The charging rate here is one of the indexes for easily grasping the electric power charged in the battery, and is expressed, for example, as a percentage of the remaining capacity with respect to the capacity when fully charged. The charging rate is estimated at any time by a battery control device (not shown) built in the battery 7, and the value is transmitted to the electronic control device 9.

  The magnitude of the regenerative power generated by the motor generator 3 can be adjusted by increasing or decreasing the power supplied from the battery 7 to the motor generator 3 via the inverter 6. The magnitude of the supplied power is controlled by an electronic control device 9 described later. In the present embodiment, regenerative power generation control performed by the electronic control unit 9 when the motor generator 3 functions as a generator will be described in detail.

[1-2. Detection system]
The crankshaft of the engine 1 is provided with an engine speed sensor 11 that detects its rotation angle. The amount of change (angular speed) of the rotation angle per unit time is proportional to the engine rotation speed Ne (the rotation speed (rotation speed) per unit time is simply called the rotation speed). Therefore, it can be said that the engine speed sensor 11 has a function of acquiring the engine speed Ne. The engine speed sensor 11 calculates the engine speed Ne based on the detected rotation angle and transmits the information to the electronic control unit 9. Note that the engine speed Ne may be calculated inside the electronic control unit 9 based on information on the rotation angle detected by the engine speed sensor 11.

At an arbitrary position of the vehicle (for example, in the vicinity of an accelerator pedal or a brake pedal), an accelerator opening sensor 12 for detecting an accelerator pedal depression operation amount (accelerator opening A _PS ), and a brake pedal depression operation amount (brake opening) And a brake sensor 13 for detecting the degree _BRK ). The accelerator opening A _PS is a parameter corresponding to the driver's acceleration request, and the brake opening _BRK is a parameter corresponding to the driver's deceleration request. Both the information on the accelerator opening A _PS and the brake opening B _RK are transmitted to the electronic control unit 9 and reflected in the output request to the engine 1.

  A vehicle speed sensor 14 for detecting the vehicle speed V and a road surface gradient sensor 15 are provided at an arbitrary position of the vehicle 20. The vehicle speed sensor 14 detects (or calculates) the vehicle speed V based on a pulse signal proportional to the rotation angle and rotation speed of the axle. The road surface gradient sensor 15 detects a gradient G (inclination gradient) of the road surface on which the vehicle 20 travels. Information on the vehicle speed V and the gradient G detected here is transmitted to the electronic control unit 9.

[2. Control device]
[2-1. Overview of control]
A vehicle equipped with the engine 1 is provided with an electronic control unit 9 (Engine Electronic Control Unit, engine ECU). The electronic control unit 9 is configured as, for example, an LSI device or a built-in electronic device in which a microprocessor, ROM, RAM, and the like are integrated, and is connected to a communication line of an in-vehicle network network provided in the vehicle.

As shown in FIG. 1, an engine speed sensor 11, an accelerator opening sensor 12, a brake sensor 13, a vehicle speed sensor 14, a road surface gradient sensor 15, an inverter 6, and a battery 7 are connected to the input side of the electronic control unit 9. The The automatic transmission 4 is connected to the output side of the electronic control unit 9.
The electronic control unit 9 is an electronic control unit that comprehensively controls a wide range of systems such as an ignition system, a fuel system, an intake / exhaust system, and a valve system related to the motor generator 3 and the engine 1. In addition, the amount of air supplied to each cylinder of the engine 1, the fuel injection amount, the ignition timing of each cylinder, and the like are controlled.
The electronic control unit 9 also adjusts the gear ratio of the automatic transmission 4 during regenerative power generation of the motor generator 3 to control the friction loss of the engine 1 and the motor generator 3.

The friction loss of the engine 1 here includes intake and exhaust loss and mechanical loss. The intake / exhaust loss (pumping loss) is a friction loss caused by a pressure change in the intake / exhaust system, and is also called a pressure loss. In addition, the mechanical loss is a friction loss caused by the operation of the piston, valve, and auxiliary machinery.
The friction loss of the motor generator 3 here includes mechanical loss and load loss. The mechanical loss is a loss derived from the structure of the motor generator 3 and includes a friction loss at the bearing, a pressure loss caused by rotation of the rotor, and the like. The load loss is a loss derived from an electrical resistance, such as an electrical resistance of a copper wire, an electric field generated by a current flowing through a coil, or a resistance loss due to a magnetic field.

  The braking force (regenerative braking force) obtained at the time of regenerative power generation corresponds to the power stored in the battery 7 by regenerative power generation. That is, the regenerative braking force is weak when the power generation amount is small, and the regenerative braking force is strong as the power generation amount is large. On the other hand, not all of the kinetic energy of the vehicle 20 input to the motor generator 3 is converted into electric energy. In the present embodiment, it is considered that the sum of the thermal energy and electric energy generated in accordance with the friction loss inside the motor generator 3 corresponds to the kinetic energy input to the motor generator 3. Therefore, when the rotation speed and torque input to the motor generator 3 are constant, the smaller the friction loss of the motor generator 3, the higher the power generation efficiency of electric energy.

  From this point of view, the electronic control unit 9 determines the rotational speed at which the sum of the friction loss of the engine 1 and the friction loss of the motor generator 3 is not more than a predetermined amount (that is, the power generation efficiency of the motor generator 3 is not less than the predetermined efficiency). Rotational speed) is calculated, and the gear ratio of the automatic transmission 4 is controlled so that the driving force is input from the driving wheel 5 side at the rotational speed. Preferably, the rotational speed at which the sum of the friction loss of the engine 1 and the friction loss of the motor generator 3 is minimized (that is, the rotational speed at which the power generation efficiency of the motor generator 3 is maximized) is calculated, and the driving force of the rotational speed is calculated. The gear ratio of the automatic transmission 4 is controlled so that is input from the drive wheel 5 side. Moreover, when calculating said rotation speed, the various characteristics of the engine 1 and the motor generator 3 as shown in FIGS. 2-4 are utilized.

As shown in FIG. 2, when the engine speed Ne is relatively low, the friction loss torque of the engine 1 fluctuates gently by drawing a downwardly convex curve graph and the amount of fluctuation is slight. It is. On the other hand, when the engine speed Ne becomes relatively high, the friction loss torque increases as the engine speed Ne increases.
As shown in FIG. 2, when the drive torque T _IN input to the engine 1 from the drive wheel 5 side is constant, there is a rotation speed at which the friction loss torque is minimized. If the engine speed Ne is called the minimum loss engine speed Ne ₀ , the amount of increase in the friction loss torque decreases as the engine engine speed Ne approaches the minimum engine speed Ne ₀ , and the engine engine speed Ne departs from the minimum engine speed Ne _0. As the friction loss torque increases, the amount of increase increases.

Further, as shown in FIG. 3, the friction loss torque of the motor generator 3 has similar characteristics. Hereinafter, the rotational speed of the motor generator 3 in a state of functioning as a generator will be expressed as a generator rotational speed Ng, and the friction of the motor generator 3 when the driving torque T _IN input from the driving wheel 5 side is constant. the rotational speed of torque loss is minimum is called a minimum loss rpm Ng _0. The increase amount of the friction loss torque is smaller as the generator rotational speed Ng is closer to the minimum loss rotational speed Ng ₀ and increases as the generator rotational speed Ng is farther from the minimum loss rotational speed Ng ₀ . Further, the friction loss torque and the minimum loss rotation speed Ng ₀ of the motor generator 3 change according to the drive torque T _IN input to the motor generator 3.

[2-2. Calculation element]
As shown in FIG. 1, the electronic control unit 9 includes a required braking force calculation unit 9a, a regenerative capacity calculation unit 9b, an engine braking force calculation unit 9c, a rotation speed calculation unit 9d, and a control unit 9e. Each of these elements may be realized in the form of an electronic circuit (hardware), may be programmed in the form of software, or some of these functions may be provided as hardware, The other part may be software.

Required braking force calculation unit 9a at the time of regeneration, and thereby calculates the required braking force F ₁ which is required in the vehicle 20. Here, for example, the engine speed Ne, the vehicle speed V, the gradient G, based on the accelerator opening A _PS and the brake opening B _RK, required braking force F ₁ is calculated from the preset control map or an arithmetic expression or the like. Wherein information of the requested braking force F ₁ which is calculated is transmitted to the control unit 9e.

The regenerative capacity calculating unit 9b calculates a regenerative capacity F ₂ that is a regenerative braking power corresponding to the maximum power (maximum generated power) that can be generated by the motor generator 3 in the traveling state of the vehicle 20 at that time. Is. Here, for example, the engine speed Ne, the vehicle speed V, the basis of the amount of charge of the gradient G and the battery 7, regenerative capacity F ₂ is calculated from the preset control map or an arithmetic expression or the like.
Further, the required braking force calculation portion 9a, when the target rotational speed Nt is calculated in the rotational speed calculating portion 9d which will be described later, calculates a regenerative capacity F _2A is a regenerative braking force at the target rotation speed Nt . The information of the regenerative ability F ₂ and F _2A calculated here is transmitted to the control unit 9e.

Engine braking force calculation section 9c is for calculating engine braking force F ₃ which may be generated by the engine 1 during regeneration. Here, based on the control state of the engine 1, the engine speed Ne, the vehicle speed V, the gradient G, the accelerator opening A _PS, and the brake opening B _RK , the engine braking force F _{3 is determined} from a preset control map, an arithmetic expression, or the like. Is calculated.

The engine braking force calculation section 9c, when the target rotation speed Nt is calculated in the rotational speed calculating portion 9d which will be described later, calculates the engine braking force F _3A at the target rotation speed Nt. Information on the engine braking forces F ₃ and F _3A calculated here is transmitted to the control unit 9e.
Regarding specific calculation methods of required braking force F ₁ , regenerative ability F ₂ , F _2A , and engine braking force F ₃ in required braking force calculation unit 9a, regenerative capability calculation unit 9b, and engine braking force calculation unit 9c. In addition to the above method, various known methods may be applied.

The rotation speed calculation unit 9d (rotation speed calculation means) calculates a rotation speed target value at which the power generation efficiency of the motor generator 3 is equal to or higher than a predetermined efficiency as the target rotation speed Nt. In other words, the rotation speed calculation unit 9d calculates the target value of the rotation speed at which the friction loss in the motor generator 3 is equal to or less than a predetermined amount as the target rotation speed Nt. Here, first, the drive torque T _IN input to the motor generator 3 from the drive wheel 5 side is calculated. The drive torque T _IN is calculated based on, for example, the engine speed Ne, the vehicle speed V, the gradient G, and the like.

Subsequently, the rotational speed calculation unit 9d calculates the target rotational speed Nt that should actually rotate the motor generator 3 when the driving torque _TIN is input, taking into account the friction loss of the motor generator 3. The target rotational speed Nt is the rotational speed at which the friction loss at the motor generator 3 is less than or equal to a predetermined amount.
As specific calculation methods of the target rotation speed Nt, the following three methods are exemplified. The target rotational speed Nt calculated here is transmitted to the controller 9e. When the regenerative power generated when the motor generator 3 rotates at the target rotational speed Nt set here exceeds the regenerative capacity F ₂ (for example, when the charge amount of the battery 7 is sufficiently high). The target rotational speed Nt may be set smaller.

[2-2-1. First method]
The first method for calculating the target rotational speed Nt is to calculate the rotational speed at which the friction loss that can occur inside the motor generator 3 is minimized, and this is set as the target rotational speed Nt. As shown in FIG. 3, the friction loss of the motor generator 3 with respect to the predetermined drive torque T _IN takes a minimum value at the minimum loss rotation speed Ng ₀ . Therefore, a table in advance and map the value of the minimum loss rpm Ng ₀ per drive torque T _IN, by storing an arithmetic expression or the like, it is possible to obtain the minimum loss rpm Ng _0.

The graph of FIG. 4A represents the distribution of the power generation efficiency η _A of the motor generator 3 in correspondence with the drive torque T _IN and the generator rotational speed Ng. Here, if the electric energy generated by the motor generator 3 is referred to as power generation, and the energy required to drive the motor generator 3 is referred to as driving power, the power generation efficiency η _A is obtained by dividing the power generation by the driving power. It corresponds to a thing. Further, the generated power is equal to a value obtained by subtracting the energy of the friction loss of the motor generator 3 from the driving force.

Therefore, the power generation efficiency η _A fluctuates in the range of 0 to 1, the power generation efficiency η _A approaches (decreases) as the friction loss of the motor generator 3 increases, and the power generation efficiency η _A becomes 1 as the friction loss decreases. Approach (increase). The region where the power generation efficiency η _A is high is a power generation region where the friction loss of the motor generator 3 is small, and can be said to be a power generation region where the friction of the motor generator 3 is small.

Further, the equal torque region in FIG. 4A means an operation region where the motor generator 3 operates at a generator rotational speed Ng in a range of 0 ≦ Ng <N _MIN , and the equal horsepower region means N _MIN ≦ <Ng means an operating region that operates at a generator speed Ng in the range of Ng. The maximum value of the drive torque T _{IN that} can be input to the motor generator 3 in the equal torque region is preset according to the product characteristics of the motor generator 3. Further, the maximum value of the drive torque T _{IN that} can be input to the motor generator 3 in the equi-horsepower region is the maximum torque that makes the product of the generator rotational speed Ng and the drive torque T _{IN at} that time equal to or less than a predetermined value. A line indicated by a thick solid line in FIG. 4A is the maximum value of these drive torques _TIN .

In this graph, the region where the power generation efficiency η _A is higher than the maximum predetermined efficiency η _A1 (the region where the power generation efficiency η _A is the highest) is the maximum drive torque T _IN as shown by hatching in FIG. It is located below the thick solid line indicating the value. Further, the broken line graph in FIG. _4A is a plot of the rotational speed at which the power generation efficiency η _A is maximum for an arbitrary driving torque T _IN as the optimal efficiency rotational speed N _OPTA . Therefore, the target rotational speed Nt may be obtained from the relationship between the drive torque T _IN and the optimum efficiency rotational speed N _OPTA shown in this broken line graph. For example, the optimum efficiency rotational speed N _OPTA may be defined as a function of the driving torque T _{IN in} a map, a table, a mathematical expression, or the like, and the target rotational speed Nt may be obtained from the driving torque T _IN using these.

[2-2-2. Second method]
The second method is to calculate the rotational speed at which the friction loss that can occur inside both the engine 1 and the motor generator 3 is minimized, and set this as the target rotational speed Nt. As shown in FIGS. 2 and 3, the friction loss inside the engine 1 can be obtained from the engine rotational speed Ne in the same manner as the friction loss inside the motor generator 3. Accordingly, the rotational speed at which the friction loss at the motor generator 3 is minimized and the rotational speed at which the friction loss at the engine 1 is minimized can be calculated, and the minimum loss rotational speed Ng ₀ can be obtained based on these.

The graph of FIG. 4B shows the distribution of the power generation efficiency η _B when the friction loss in the engine 1 is taken into consideration. Here, the sum of the energy required for driving the motor generator 3 and the energy of the friction loss of the engine 1 is referred to as a second driving force. The power generation efficiency η _B corresponds to the generated power divided by the second driving force.

Comparing the graphs of FIGS. 4A and 4B, the region where the power generation efficiency η _B is higher than the maximum predetermined efficiency η _B1 (the region where the power generation efficiency η _B is the highest) in FIG. It moves in the direction of lower rotational speed and higher driving torque than in the case of 4 (a). Further, the broken line graph in FIG. 4B is a graph in which the rotation speed at which the power generation efficiency η _B is maximum is plotted as the optimum efficiency rotation speed N _OPTB for an arbitrary drive torque T _IN . Therefore, the target rotation speed Nt may be obtained from the relationship between the drive torque T _IN and the optimum efficiency rotation speed N _OPTB shown in the broken line graph. For example, as in the first method, the optimum efficiency rotational speed N _OPTB is defined as a function of the driving torque T _{IN in} a map, table, formula, etc., and the target rotational speed Nt can be obtained from the driving torque T _IN using these. That's fine.

  In addition, it turns out that the fluctuation range of the generator rotation speed Ng is narrower than the broken line graph in FIG. 4A in the broken line graph in FIG. Therefore, when the second method is used, fluctuations in the rotational speed of the motor generator 3 are suppressed more than when the first method is used.

[2-2-3. Third method]
Said 1st and 2nd method is a method of calculating | requiring generator rotation speed Ng which minimizes friction loss. The smaller the friction loss, the smaller the amount of heat generated in the motor generator 3. Therefore, in order to minimize the heat generation amount, it is preferable to use the first and second methods for calculating the rotational speed at which the friction loss is minimized. On the other hand, the third method is not the rotational speed at which the friction loss is minimized, but the friction loss is not more than the first predetermined amount and becomes the minimum within the range of the second predetermined amount which is smaller than the first predetermined amount. The number of revolutions. In other words, the rotational speed at which the power generation efficiency is greater than or equal to the first predetermined efficiency and less than or equal to the second predetermined efficiency that is greater than the first predetermined efficiency, and further at a rotational speed that maximizes the power generation efficiency within this range. is there. This method is suitable for use when it is desired to set the lower limit value of the amount of heat generated by the motor generator 3.

  For example, energy lost due to reduction in friction loss of the motor generator 3 during regenerative braking is converted into heat as friction loss (engine brake) of the engine 1 interposed in the power transmission path. Or it is converted into thermal energy as friction loss (foot brake) of a wheel braking device (not shown). Therefore, if the friction loss of the motor generator 3 is reduced to the minimum with the braking force of the engine brake acting at the maximum, the surplus energy cannot be consumed by the engine 1 and the load on the braking device increases. Will do. In such a case, the generator rotational speed Ng may be obtained such that the power generation efficiency is not less than the first predetermined efficiency and not more than the second predetermined efficiency.

FIG. 4C is a diagram in which the shape of the broken line graph in FIG. 4A is changed, and the rotational speed at which the power generation efficiency η _A is maximum within the range of the predetermined efficiency η _A1 or less is determined as the appropriate efficiency rotational speed N _OPTC. Are plotted. Therefore, the target rotational speed Nt may be obtained from the relationship between the drive torque T _IN and the appropriate efficiency rotational speed N _OPTC shown in the broken line graph. For example, as in the first and second methods, the optimum efficiency rotational speed N _OPTC is defined as a function of the driving torque T _{IN in} a map, table, formula, etc., and using these, the target rotational speed is determined from the driving torque T _IN. Find Nt.

[2-3. Control element]
The control unit 9e (gear ratio control means) includes a required braking force F ₁ calculated by the required braking force calculation unit 9a, a regenerative capability F ₂ and F _2A calculated by the regenerative capability calculation unit 9b, and an engine braking force calculation unit. Based on the engine braking force F ₃ , F _3A calculated in 9c, the target rotational speed Nt and the vehicle speed V set in the rotational speed calculating section 9d, the speed ratio of the automatic transmission 4 is determined and controlled. It is. By controlling the gear ratio of the automatic transmission 4, the rotational speed input to the motor generator 3 becomes the target rotational speed Nt, and regenerative power generation is performed with a desired power generation efficiency.

The controller 9e, the drive wheel rotation speed N _IN is calculated based on the vehicle speed V, the ones the target rotation speed Nt divided by the drive wheel rotational speed N _IN is calculated as the optimum efficiency speed ratio R. The optimum efficiency gear ratio R is a gear ratio for setting the upstream rotational speed of the automatic transmission 4 (that is, the rotational speed input to the motor generator 3) to the target rotational speed Nt. The control unit 9e outputs a control signal for setting the gear ratio of the automatic transmission 4 to the optimum efficiency gear ratio R during the regenerative power generation of the motor generator 3.

In the present embodiment, when the motor generator 3 is driven at the optimum efficiency rotational speed N _OPT , the added value of the regenerative capability F _2A and the engine braking force F _3A generated by the motor generator 3 is the required braking force F _1. if it is less than the control portion 9e to practice the control to enhance the engine braking force F _3A. For example, the intake / exhaust loss of the engine 1 may be increased by closing the throttle valve or the exhaust throttle valve to increase the engine braking force F _3A , or other various known methods may be applied. In the case of the vehicle 20 including an automatic brake device that automatically controls the wheel braking device, the control unit 9e may activate the automatic brake.

[3. flowchart]
FIG. 5 is a flowchart for explaining the speed ratio control during regenerative power generation executed by the electronic control unit 9. The control shown in this flowchart is repeatedly performed at a predetermined cycle (for example, several tens [ms] cycle) set in advance.

In step A <b> 10, information (regeneration mode information) regarding the operating states of the engine 1 and the motor generator 3 is transmitted from the inverter 6 to the electronic control device 9. Here, for example, information related to regenerative power and supplied power in the motor generator 3 is input to the electronic control device 9. Information such as the engine speed Ne, the vehicle speed V, the gradient G, the accelerator opening _APS, and the brake opening _BRK is also input to the electronic control unit 9.
In step A20, it is determined whether or not the motor generator 3 is in a traveling state in which it can function as a generator (that is, whether or not it is in a traveling state in which regenerative power generation can be performed). If the vehicle is in a traveling state where regenerative power generation can be performed, the process proceeds to step A40. On the other hand, when it is not the driving | running | working state which can implement regenerative power generation, it progresses to step A30, regenerative power generation is not implemented, and this flow is complete | finished.

In step A40, the required braking force calculation unit 9a, the engine speed Ne, the vehicle speed V, the gradient G, based on the accelerator opening A _PS and the brake opening B _RK, demand braking force F ₁ which is required in the vehicle 20 Calculated. Moreover, the subsequent step A50, based on the vehicle speed V, the drive wheel rotation speed N _IN inputted from the driving wheels 5 to the automatic transmission 4 is calculated. In step A60, based on the vehicle speed V, the gradient G, the accelerator opening degree A _PS and the brake opening B _RK, the driving torque T _IN inputted from the automatic transmission 4 to the motor generator 3 is calculated. The drive torque T _IN is input not only from the automatic transmission 4 to the motor generator 3 but also to the engine 1.

In step A70, the revolution calculating unit 9d, the target rotation speed Nt corresponding to the drive torque T _IN is set. This target rotational speed Nt is set based on, for example, the relationship between the optimum efficiency rotational speed N _OPTA and the drive torque T _IN indicated by a broken line in FIG. Further, at step A80, the regenerative capability calculating section 9b calculates the regenerative capability F _2A at the target rotational speed Nt, and at step A90, the engine braking force calculating section 9c calculates the engine braking force F _3A at the target rotational speed Nt. Calculated.

In Step A100, it is determined whether or not the added value of the regenerative capability F _2A and the engine braking force F _3A is equal to or greater than the required braking force F ₁ required for the vehicle 20. If F ₁ > F _2A + F _3A , the process proceeds to step A110, and control for increasing the engine braking force F _3A is performed in the control unit 9e. On the other hand, if F ₁ ≦ F _2A + F _3A , the process proceeds to step A120.

In step A 120, the value of the target rotation speed Nt divided by the drive wheel rotational speed N _IN is calculated as the optimum efficiency speed ratio R in the control unit 9e. In subsequent step A130, a control signal corresponding to the optimum efficiency gear ratio R is output from the control unit 9e to the automatic transmission 4, and the gear ratio of the automatic transmission 4 is controlled. In Step A140, regenerative power generation is performed with the rotation speed and drive torque input to the motor generator 3, and this flow ends.

[4. Action, effect]
(1) In the above regeneration control device, the target rotational speed Nt is set based on the power generation efficiency characteristic of the motor generator 3. In other words, the target rotational speed Nt is set based on the friction loss characteristics of the motor generator 3, and the motor generator 3 is driven at the rotational speed at which the power generation efficiency increases. Therefore, friction loss that can occur inside the motor generator 3 can be reduced, and unnecessary heat generation can be suppressed. Thereby, the power generation efficiency at the time of regenerative power generation can be maintained above a predetermined efficiency, and the fuel consumption of the vehicle 20 can be improved.

Further, the energy corresponding to the heat loss of the motor generator 3 is borne by the engine 1 and the braking device. Therefore, it is possible to easily prevent a temperature drop of the engine 1. For example, when regenerative power generation is performed for a relatively long time in a cold region, the thermal energy associated with the friction loss of the engine 1 can be increased. Thereby, the thermostatic property of the engine 1 can be improved and control stability can be improved.
Further, by driving the motor generator 3 at a rotational speed with a small friction, it is possible to suppress the progress of wear and deterioration of the rotor inside the motor generator 3. Therefore, the product life of the motor generator 3 can be extended.

As shown in FIG. 4A, when the drive torque T _IN input to the motor generator 3 changes from the first torque T _IN1 to the second torque T _IN2 , the conventional power generation amount is maximized. When regenerative power generation is performed, the generator rotational speed Ng varies from the first rotational speed Ng ₁ to the second rotational speed Ng ₂ . On the other hand, in the regenerative power generation of the regenerative control device described above, the generator rotational speed Ng varies only from the first rotational speed Ng ₁ to the third rotational speed Ng ₃ .

That is, the motor generator 3 is driven at a rotational speed that is lower than the second rotational speed Ng ₂ and has good power generation efficiency. As described above, the fluctuation of the rotational speed with respect to the fluctuation of the driving torque T _IN input to the motor generator 3 can be reduced, and the power generation amount and the regenerative braking force can be stabilized. Further, since the power generation amount and the regenerative braking force are stabilized, a sudden change in the engine braking force that the engine 1 must bear can be suppressed.
Thus, according to the above-described regenerative control device, it is possible to improve the overall control stability during regenerative power generation while continuing power generation with guaranteed power generation efficiency.

  (2) In the above regeneration control device, the rotation speed at which the power generation efficiency is maximized by the torque input to the motor generator 3 is set as the target rotation speed Nt. That is, since the motor generator 3 is driven at the rotation speed at which the friction loss is the smallest, the regenerative power generation can be performed efficiently. Further, even when regenerative power generation is performed for a long time, the temperature increase of the motor generator 3 can be suppressed, and the amount of power generated can be stabilized.

(3) Furthermore, using the power generation efficiency characteristic as shown in FIG. 4B, the target rotational speed Nt is based on the power generation efficiency η _B in which the friction loss characteristic of the engine 1 is considered as well as the motor generator 3. Is set, unnecessary heat generation in the engine 1 and the motor generator 3 can be suppressed.
For example, during regenerative power generation in a tropical region where the outside air temperature is high, the operation stability of these devices can be improved by reducing the amount of heat generated by the engine 1 and the motor generator 3. The insufficient braking force is converted into thermal energy as friction loss by operating the automatic braking device or by operating the braking device in response to a braking operation by the driver. Therefore, the temperature rise of the engine 1 and the motor generator 3 can be suppressed.

(4) In addition, when the power generation efficiency characteristic as shown in FIG. 4C is used and the rotation speed at which the power generation efficiency η _A is maximum within the predetermined efficiency η _A1 or less is set as the target rotation speed Nt. Can consume the energy at the time of braking by using the friction loss of the engine 1 and the motor generator 3, and can reduce the burden on the braking device and the automatic braking device. In this way, the heat generation loss inside the engine 1 and the motor generator 3 is not extremely minimized, but the energy required for braking is distributed to the braking device while being moderately reduced. The overall control stability can be improved.

[5. Modified example]
Regardless of the embodiment described above, various modifications can be made without departing from the spirit of the invention. Each structure of this embodiment can be selected as needed, or may be combined appropriately.

[5-1. Individual control of rotation speed]
In the above-described embodiment, the vehicle 20 having a structure in which the output shaft of the engine 1 and the rotation shaft of the motor generator 3 are directly connected via the clutch 2 is illustrated, but the engine 1 and the motor generator 3 are not directly connected. Is possible. In this case, since the engine rotational speed Ne and the generator rotational speed Ng are different, a means for controlling the rotational speed of the engine 1 is provided separately from the means for controlling the rotational speed of the motor generator 3. Can be considered.

A vehicle 30 shown in FIG. 6 is a series / parallel mixed type hybrid electric vehicle that can run using both the engine 1 and the pair of motor generators 3a and 3b as drive sources. Here, the elements corresponding to the elements described in the above embodiment and the same elements are denoted by the same reference numerals, and the description thereof is omitted.
A power split mechanism 8 is provided on the downstream side of the clutch 2 of the vehicle 30, and torque output from the engine 1 is distributed to the first motor generator 3a and the second motor generator 3b. The power split mechanism 8 is a power transmission device incorporating the planetary gear mechanism, the CVT mechanism, the clutch / brake mechanism, etc. described above, for example, and the ratio of the rotational speeds of the engine 1, the first motor generator 3a and the second motor generator 3b ( Torque ratio) can be changed.

  The first motor generator 3a and the second motor generator 3b are motor generators each functioning as a motor (electric motor) or a generator (generator). Therefore, for example, the vehicle 30 can be driven with the driving force of only the second motor generator 3b, or the vehicle 30 can be driven with the driving force of only the engine 1. It is also possible to operate the second motor generator 3b as an electric motor while the first motor generator 3a generates power with the driving force of the engine 1 while the vehicle 30 is traveling.

An automatic transmission 4 is interposed between the second motor generator 3 b and the drive wheel 5. The ratio between the rotational speed of the engine 1 and the rotational speed of the drive wheel 5 is a value corresponding to the transmission ratio of the automatic transmission 4 and the transmission ratio of the power split mechanism 8. On the other hand, the ratio between the rotational speed of the second motor generator 3 b and the rotational speed of the drive wheel 5 is a value corresponding only to the gear ratio of the automatic transmission 4. Therefore, by individually controlling the transmission ratio of the automatic transmission 4 and the transmission ratio of the power split mechanism 8, the rotational speed of the engine 1 and the rotational speed of the second motor generator 3b during regenerative power generation are independent of each other. It is possible to control.
Therefore, in the present modification, the electronic control device 9 is configured so that the friction loss of the second motor generator 3b is minimized and the friction loss of the engine 1 is minimized as control during the regenerative power generation of the second motor generator 3b. Thus, the gear ratio of the automatic transmission 4 and the gear ratio of the power split mechanism 8 are individually controlled.

As shown in FIG. 6, the rotation speed calculation section 9 d of the electronic control device 9 is provided with a generator rotation speed calculation section 21 and an engine rotation speed calculation section 22. Generator rotational speed calculating section 21 is for power generation efficiency of the second motor generator 3b is a target value of the rotational speed becomes a predetermined efficiency or more is calculated as the first target engine speed Nt _1. In other words, the generator rotational speed calculating section 21 calculates the rotation speed target value friction loss is equal to or less than a predetermined amount of the second motor generator 3b as the first target engine speed Nt _1. For example, to set the rotational speed of the power generation efficiency is highest with respect to the drive torque T _IN inputted to the second motor generator 3b as the first target engine speed Nt ₁ is a broken line graph in FIG. 4 (a) The first target rotational speed Nt ₁ is set from the relationship between the drive torque T _IN and the optimum efficiency rotational speed N _OPTA .

Engine rotational speed computing section 22 is a friction loss of the engine 1 is set a target value of the rotational speed equal to or less than a predetermined amount as the second target engine speed Nt _2. Here, for example, as shown in FIG. 2, the second target speed Nt ₂ is set from the relationship between the friction loss torque and the engine speed Ne. Information on the first target rotational speed Nt ₁ and the second target rotational speed Nt ₂ is transmitted to the control unit 9e.

The control unit 9e is provided with a first gear ratio control unit 23 and a second gear ratio control unit 24.
The first change gear ratio control unit 23, the rotational speed of the upstream side of the automatic transmission 4 (i.e., the rotational speed inputted to the second motor generator 3b) the first change gear ratio for the the first target engine speed Nt ₁ R ₁ is calculated, and a control signal for setting the gear ratio of the automatic transmission 4 to the first gear ratio R ₁ is output. The first speed ratio R ₁ is a value obtained by dividing the first target rotational speed Nt ₁ by the drive wheel rotational speed N _IN .

On the other hand, the second change gear ratio control unit 24, the upstream side of the rotational speed of the power split device 8 (i.e., the rotational speed inputted to the engine 1) the second change gear ratio for the the second target engine speed Nt ₂ R ₂ is calculated, and a control signal for setting the gear ratio of the power split mechanism 8 to the second gear ratio R ₂ is output. The second speed ratio R ₂ is a value obtained by dividing the second target rotational speed Nt ₂ by the rotational speed of the second motor generator 3b (ie, the first target rotational speed Nt ₁ ).
By such control, regenerative power generation can be efficiently performed while minimizing heat loss in the second motor generator 3b and the engine 1. Thereby, it is possible to improve the overall control stability during regenerative power generation while continuing power generation with guaranteed power generation efficiency.

[5-2. Others]
In the above-described embodiment, the regenerative control device having the electronic control device 9 that controls the engine 1 and the motor generator 3 mounted on the vehicle 20 is illustrated, but the control target of the electronic control device 9 is not limited to this. The electronic control unit 9 can be applied as a control unit for an internal combustion engine such as a gasoline engine or a diesel engine mounted on a vehicle, a ship, an aircraft, an industrial machine, or the like.

  Moreover, although the above-mentioned embodiment explained in full detail the control at the time of the regenerative power generation by the motor generator 3 of a hybrid vehicle, the application object of this invention is not limited only to a hybrid vehicle. As long as the vehicle includes a generator and an alternator that perform regenerative power generation using the driving force transmitted from the drive wheel side, the control of the above-described embodiment can be performed.

1 Engine 3 Motor generator (generator)
4 Automatic transmission (transmission)
DESCRIPTION OF SYMBOLS 9 Electronic control apparatus 9a Required braking force calculating part 9b Regenerative ability calculating part 9c Engine braking force calculating part 9d Rotational speed calculating part (Rotational speed calculating means)
9e Control unit (speed ratio control means)

Claims (3)

A generator connected to the power transmission path of the engine and performing regenerative power generation with torque transmitted from the drive wheels;
A transmission interposed between the generator and the drive wheel;
Based on the power generation efficiency characteristics of the generator, a rotation speed calculation means for calculating the rotation speed of the generator with which the power generation efficiency is equal to or higher than a predetermined efficiency by the torque input to the generator;
A transmission ratio control means for determining a transmission ratio of the transmission at the time of regenerative power generation of the generator based on the rotational speed calculated by the rotational speed calculation means ;
The rotational speed calculation means calculates the rotational speed of the generator that generates a power generation efficiency equal to or lower than a second predetermined efficiency higher than the predetermined efficiency by a torque input to the generator. , Regenerative control device. The generator has a rotating shaft directly connected to the rotating shaft of the engine,
The rotational speed calculation means, based on the frictional loss characteristics of the the power generation efficiency characteristics of the generator engine, characterized by calculating the rotational speed of the generator, regenerative control device according to claim 1. A second transmission interposed between the engine and the drive wheel or the generator;
The generator is non-directly connected to the rotating shaft of the engine,
The rotation speed calculating means is
Based on the power generation efficiency characteristics of the generator, a first rotation speed calculation means for calculating a first rotation speed of the generator with which the power generation efficiency is equal to or higher than a predetermined efficiency with torque input to the generator;
Based on the friction loss characteristics of the engine, and a second rotation speed calculation means for calculating a second rotation speed of the engine at which the friction loss of the engine is a predetermined amount or less,
The transmission ratio control means is
First speed ratio control means for controlling a speed ratio of the transmission based on the first speed calculated by the first speed calculation means;
Based on the second rotational speed that is calculated by the second rotation speed calculation means, and having a second gear ratio control means for controlling a speed ratio of the second transmission, according to claim 1, wherein Regenerative control device.

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