JP2011188557A - System and method for controlling extension of distance-to-empty by powering regenerative distribution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system and a method for controlling extension of a distance-to-empty by powering regenerative distribution, for improving efficiency of a motor-driven vehicle by controlling a braking force of each of motors so that the total efficiency of all the motors becomes maximum. <P>SOLUTION: The distance-to-empty extension control system 100 is constituted of an optimum torque distribution ratio calculating unit 101 and a torque distribution control unit 102. The optimum torque distribution ratio calculating unit 101 selects an approximate formula of an optimum torque distribution ratio γ<SP>*</SP>against a total torque command T<SB>ref</SB>corresponding to the mean wheel speed of actual time, which has been calculated and stored in advance, and substitutes the total torque command T<SB>ref</SB>in the approximate formula to calculate the optimum torque distribution ratio γ<SP>*</SP>with which total efficiency η<SB>all</SB>becomes the maximum. The torque distribution control unit 102 calculates a torque command value for each motor from the optimum torque distribution ratio γ<SP>*</SP>, and outputs the torque command values to each motor. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cruising distance extension control system and method by power running regeneration distribution, and more specifically, cruising distance extension control by power running regeneration distribution for controlling braking / driving force of each motor so that the overall efficiency of all motors is maximized. The present invention relates to a system and method.

  In recent years, attention has been focused on hybrid, electric, and fuel cell vehicles that use a motor as a driving force source. In particular, the leap of hybrid vehicles using liquid fuel with a high volumetric energy density is remarkable (see Non-Patent Document 1). Toyota's Prius and Honda Motor's Insight gained first place in monthly new vehicle sales this year.

  There are various hybrid methods such as series, parallel, and a combination of series / parallel, depending on how the engine, motor, and battery are combined. Each automobile manufacturer is conducting research and development (see Non-Patent Document 2).

  However, there are drawbacks such as a large battery mass, few power supply facilities, and a short one-charge travel distance. Therefore, various studies have been made to overcome the shortcomings of one charging mileage. For example, there is one that aims to improve the overall efficiency by changing the control method of an inverter or chopper for driving a motor (see Non-Patent Document 3). In addition, there is one that aims to extend the mileage by improving the convenience of charging by installing a non-contact power supply device in an electric vehicle rather than improving the efficiency and charging frequently (non-patent) Reference 4). In addition, there is one that aims to improve motor efficiency by changing motor parameters during traveling to perform driving suitable for traveling conditions (see Non-Patent Document 5). Moreover, there exists what is called a range extender as an existing cruising distance extension device. An engine and a generator are generally used for the range extender. When the remaining amount of power charged in the battery decreases, the cruising distance is ensured by turning the generator with the engine and supplying the generated power to the motor for running. However, this requires cost and in-vehicle space for mounting the device, and increases the weight. Furthermore, it is bad for the environment because the engine burns gasoline.

Ei Ohno: “Automotive technology and transportation systems in a low-carbon society”, Journal of the Institute of Electrical Engineers of Japan, Vol. 129, no. 1, pp20-pp23, 2009 Shigeru Okuma, Tatsuo Teratani, Shinji Michiki: “Electric technology in hybrid electric vehicles”, Journal of the Institute of Electrical Engineers of Japan, Vol. 127, no. 2, pp98-pp101, 2007 Sho Inasaka, Atsio Kawamura, Yukinori Genda: “A Study on High-Efficiency Power Control of Electric Vehicles Using Bidirectional Chopper”, 2009 IEEJ Industrial Application Conference, VOL. 1, ppI-667-ppI-670, 2009 Yuji Kamiya, Yasuhiro Daisei, Hidetoshi Matsuki: “Non-contact fast charging system for electric vehicles”, Journal of the Institute of Electrical Engineers of Japan, Vol. 128, no. 12, pp804-pp807, 2008 Kinhironaka, Satoru Okabe, Taizo Miyazaki, Noriaki Hino: "Operation Principle and Basic Characteristics of Variable Speed Motor Using Permanent Magnet", 2009 Annual Conference of the Institute of Electrical Engineers of Japan, 5-016, pp26-pp27, 2009

  However, although there are many advantages compared to automobiles with internal combustion engines, factors that prevent the spread of electric cars include infrastructure maintenance and higher prices than conventional cars. To solve this problem, research is being conducted on contactless power supply systems and hybrid systems that do not rely on batteries for all power sources. However, the biggest factor is short mileage for one charge. Since the electric vehicle uses the motor as the driving force as mentioned above, the one-charge travel distance depends on the capacity of the battery. In other words, unless the battery capacity becomes large, it is impossible to solve the problem of travel distance.

  The present invention has been made in view of such problems, and the object of the present invention is to control the braking / driving force of each motor so that the overall efficiency of all the motors is maximized, and to improve the efficiency of the motor-driven vehicle. It is an object of the present invention to provide a cruising range extension control system and method based on a power running / regeneration distribution that improves the above.

  In order to solve the above problems, the invention according to claim 1 is a cruising distance extension control system using power running regeneration distribution for controlling torque distribution between drive wheels, which is used in an automobile having drive wheels driven by motor torque. The overall efficiency, which is the sum of the efficiency of all the motors for each vehicle speed, is the maximum with respect to the total torque command, which is the sum of the torque commands for all the motors driving the drive wheels for each vehicle speed. Using the relational expression of the torque distribution ratio, optimal torque distribution ratio calculating means for calculating an optimal torque distribution ratio that maximizes the total efficiency from the measured vehicle body speed and the total torque command input from the driver; A torque command to be distributed to each of all the motors is calculated based on the optimum torque distribution ratio, and each of all the motors is individually calculated based on each of the calculated torque commands. Characterized by comprising a torque distribution control means for controlling the.

  According to a second aspect of the present invention, in the cruising distance extension control system based on the power running regeneration distribution according to the first aspect, the optimum torque distribution ratio is a torque distribution ratio between the front and rear wheels.

  According to a third aspect of the present invention, in the cruising distance extension control system according to the power running regeneration distribution according to the first or second aspect, the torque command to be distributed is a torque command for performing either power running or regeneration. Features.

  The invention according to claim 4 is a cruising distance extension control method by power running regeneration distribution for controlling torque distribution between drive wheels, which is used for an automobile having drive wheels driven by motor torque, and is driven at each vehicle speed. Using the relational expression of the torque distribution ratio that maximizes the total efficiency, which is the sum of the efficiency of all the motors for each vehicle speed, with respect to the total torque command, which is the sum of the torque commands for all the motors driving the wheels An optimal torque distribution ratio calculating step for calculating an optimal torque distribution ratio that maximizes the total efficiency from the measured vehicle body speed and a total torque command input from the driver; Torque commands to be distributed to each of the motors are calculated, and based on the calculated torque commands, each of the motors is individually controlled. It is characterized in that a-up.

  The invention according to claim 5 is the cruising distance extension control method by power running regeneration distribution according to claim 4, wherein the optimum torque distribution ratio is a torque distribution ratio between the front and rear wheels.

  The invention according to claim 6 is the cruising distance extension control method by power running regeneration distribution according to claim 4 or 5, wherein the torque command to be distributed is a torque command to perform either power running or regeneration. Features.

  The present invention has an effect of improving the efficiency of a motor-driven vehicle by controlling the braking / driving force of each motor so that the overall efficiency of all the motors is maximized.

(A) is a figure which shows the motor efficiency map of the motor for front wheels of an experimental vehicle, (b) is a figure which shows the motor efficiency map of the motor for rear wheels. (A), (b) is a figure which shows the case where a yaw moment does not generate | occur | produce by the torque distribution between right-and-left wheels. (A) is a figure which shows the energy relationship at the time of powering with both front-and-rear motors, (b) is a figure which shows the energy relationship at the time of front wheel powering and the rear wheel regenerating. (A)-(i) is a figure which shows the relationship between the total efficiency for every total torque command value, and distribution ratio. (A), (b) is a motor efficiency map which shows maximum efficiency when one side is power running and the other is regeneration. (A)-(i) is a figure which shows the relationship between the total efficiency for every total torque command value, and distribution ratio. It is a figure which shows the relationship between the total efficiency and allocation ratio in a real machine experiment. It is a control block diagram of a cruising distance extension control system by power running regeneration distribution concerning an embodiment of the present invention. It is a graph of the optimal torque distribution ratio γ ^* with respect to the total torque command T _ref at a speed of 60 km obtained by an approximate expression.

  In an automobile having a plurality of drive wheels, the torque value of each drive wheel has a degree of freedom because the total value of torque generated by each drive wheel only needs to satisfy the torque value required by the driver. Therefore, in the present invention, the braking / driving force control of each motor is performed so that the overall efficiency of all the motors driving the drive wheels is maximized, thereby improving the efficiency of the motor-driven vehicle.

Hereinafter, embodiments of the present invention will be described in detail.
1. Efficiency Map FIG. 1A shows a motor efficiency map of the front wheel motor of the experimental vehicle, and FIG. 1B shows a motor efficiency map of the rear wheel motor. As shown in FIGS. 1A and 1B, the efficiency of the motor varies depending on the motor speed and output torque. Therefore, in an electric vehicle in which a motor is arranged on each wheel, the efficiency varies greatly depending on at which operating point each motor is operated. While the automobile is running, the wheel speeds of the four wheels are generally the same. Therefore, in order to change the operating point of this motor while traveling at a constant speed, it is necessary to change each motor torque so that all four wheels can achieve the torque required by the driver under the same wheel speed. Good.

<1.1> Restriction conditions and overall efficiency In the present invention, as shown in FIG. 2 (a), the total torque of the left front and rear wheels and the right The total torque of the front and rear wheels is the same, and only the torque distribution of the front and rear wheels is considered. Even if there is a difference in torque between the left and right motors, the yaw moment may be canceled by another motor as shown in FIG. Torque distribution can also be applied to cancel the yaw moment.

  Note that when the yaw moment is generated by actively distributing the torque between the left and right wheels, the torque may be distributed to the individual motors so as to satisfy the torque distribution ratio between the left and right wheels necessary for generating the yaw moment.

  2 (a) and 2 (b) assume a four-wheel independent drive vehicle, the present invention is also applicable to front and rear wheel independent drive vehicles. For example, the present invention can be applied to front and rear wheel independent drive vehicles having two on-vehicle motors and a drive shaft as long as the front and rear torque distribution is limited.

2. Efficiency change based on experimental machine 2.1 Efficiency change due to torque distribution The efficiency of the motor of the experimental vehicle has the relationship shown in FIGS. 1 (a) and 1 (b). Based on this, the distribution ratio of the front and rear wheels was varied from 0 to 1.5 using equations (9) and (10), and the total efficiency η _all was calculated at each speed of 30 to 60 km. 4A to 4I show the calculation results. However, γ = 0 is the power running only for the front wheels, and γ = 1 is the power running only for the rear wheels. When γ = 1.5, the rear wheel outputs a torque 1.5 times greater than the total torque command, and the front wheel regenerates the excess, thereby realizing the total torque command.

  As can be seen from FIGS. 1 (a) and 1 (b), the sudden decrease in efficiency seen in FIGS. 4 (f) to 4 (i) decreases the maximum value of the torque as the speed increases. This is because the allocation calculation cannot be performed.

4 (a) to 4 (e), it is understood that the optimum torque distribution ratio γ ^* is determined by the speed in the range of the total torque command regardless of the magnitude of the total torque command. 4 (f) to (i), it can be seen that the optimum torque distribution ratio γ ^* becomes a value of 0.4 to 0.9 when the total torque command increases.

Similar results can be obtained by combining motors having the same efficiency map instead of motors having different characteristics as shown in FIGS. 1 (a) and 1 (b). When the motor efficiencies of all the motors are the same, the relationship between the torque distribution ratio γ and the overall efficiency is a left-right symmetric shape with the torque distribution ratio γ = 0.5 as an axis. The low torque command is convex downward (γ = 0 or 1 is maximum efficiency), and when the total torque command T _ref becomes large, it approaches the upward convex shape from the downward convex shape, and finally convex upward (γ = 0.5 is the maximum efficiency). Thus, the overall efficiency changes depending on the torque distribution ratio γ.

  Therefore, it is possible to extend the cruising distance by controlling the torque distribution ratio γ to an optimum value.

  The motor having the efficiency characteristics shown in FIG. 1 is not a motor specifically designed and manufactured for the purpose of this research. This section is an examination based on the in-wheel motor currently installed in the experimental machine, and its effectiveness can be confirmed by power running distribution, but torque distribution combining power running and regeneration does not become high efficiency, Its effectiveness is not clear. Therefore, in the next section, a motor efficiency map in the case where torque distribution combining power running and regeneration as shown in FIG.

2.2 Motor efficiency map when torque distribution combining power running and regeneration is effective FIGS. 5A and 5B show motor efficiency that shows maximum efficiency when one is power running and the other is regeneration. An example of a map is shown. The characteristics of these motor efficiency maps are that efficiency peak portions are in different regions, that is, in a high torque region (FIG. 5A) and a low torque region (FIG. 5B). Depending on the design of each parameter such as the salient pole ratio of the motor, it is considered possible to design a motor having a motor efficiency map as shown in FIGS.

6A to _6I , the relationship between the distribution ratio γ and the overall efficiency η _all is calculated for each total torque command for a plurality of speeds based on the motor efficiency maps shown in FIGS. 5A and 5B. The results are shown. As shown in FIGS. 5 (a) and 5 (b), the sudden decrease in efficiency seen in FIGS. 6 (a) to 6 (i) decreases the maximum value of the torque as the speed increases. This is because the distribution calculation cannot be performed by the torque limiter. From FIG. 6A, it can be seen that the optimum torque distribution ratio γ ^* is always 0 in this total torque command. From FIG. 7B, it can be seen that even in this total torque command, the optimum torque distribution ratio γ ^* is always 0, but the efficiency of the power running regenerative operation with γ> 1 is starting to increase. As shown in FIGS. 6D to 6G, the efficiency is finally improved in the power running regenerative operation with γ> 1 than the power running power operation with 0 <γ <1. As shown in FIGS. 6 (h) and 6 (i), when the torque command increases, the power running operation with 0 <γ <1 is more efficient.

  Further, in the case of the combination of efficiency maps as shown in FIGS. 5A and 5B, the efficiency is improved in a wide driving region by the torque distribution of the motor. The torque distribution of motors having the same efficiency map can be expected to achieve high efficiency in a narrow drive region, but it does not achieve high efficiency over a wide range like torque distribution between motors having different characteristics.

<2.3> Actual machine experiment <2.3.1> Experimental vehicle The electric vehicle FPEV2-Kanon produced uniquely was used for the experimental vehicle. The FPEV2-Kanon is equipped with four outer rotor type in-wheel motors manufactured by Toyo Denki on the front and rear wheels. This motor is a direct drive system and is not affected by backlash caused by the reduction gear. Accordingly, the reaction force information from the road surface is returned to the motor side without being lost by the gear, so that it is considered to be very effective in carrying out various estimation methods of the present invention.

  As the battery, a lithium ion battery capable of high-speed charging at a high energy density was used. Ten batteries of 16 [V] per module are connected in series and mounted. Furthermore, the system boosts the voltage to 320 [V] by using a chopper and supplies power to the inverter. An AUTOBOX made by dSPACE is installed as a controller for vehicle control.

<2.3.2> Experimental Results Experiments were performed on the front-rear torque distribution at a speed of 30 [km / h] and a total torque command of 180 [Nm]. FIG. 7 shows the experimental results. As in section 2.1, the overall efficiency η _{all of the} entire vehicle changes depending on the front-rear torque distribution.

Based on this experimental result, it converted into the travel distance per 1 [kWh]. First, the power output V _dc I _dc is integrated with the measurement time t to obtain energy E. Next, the motor speed is also integrated with the measurement time t and converted to the travel distance L. Then, the travel distance per 1 [kWh] was obtained by dividing the travel distance L by the energy E. The results are shown in Table 1.

From Table 1, the difference between the maximum value and the minimum value of the travel distance per 1 [kWh] shows an improvement of a little less than 30%. That is, one charging travel distance is extended by a little less than 30%. I-MiEV released last year is said to have a power consumption of 16 [kWh]. Therefore, when calculating with this capacity, one charging travel distance is extended by about 14 [km].

3. Cruising range extension control system (RECS: Range Extension Control System)
<3.1> Control Circuit Configuration As described above, the overall efficiency η _{all of the} vehicle varies depending on the torque distribution ratio γ. Therefore, the cruising distance of the vehicle can be extended by controlling the torque distribution ratio of each wheel so as to maximize the overall efficiency η _all .

<3.2> Derivation of optimum torque distribution ratio As one of the methods for obtaining the torque distribution ratio command value γ ^* , there is a calculation method based on <2.4> motor efficiency map obtained in an actual machine experiment.

1) In a three-dimensional map determined by the optimum torque distribution ratio γ ^* , wheel speed V, and total torque command T _ref , the wheel speed V-total torque command T _ref space is discretized and partitioned into an appropriate l × m grid.

４）式（１２）のような多項式を車輪速Ｖ_(i)毎に求める。

4) A polynomial like equation (12) is obtained for each wheel speed V _(i) .

9, the optimal torque distribution ratio gamma ^* as shown in FIG. 4, the wheel speed V, obtained by Step 1) to 5) based on the three-dimensional map determined by the total torque command T _ref, to the total torque command T _ref The graph of the optimal torque distribution ratio (gamma) ^{* in} the wheel speed 60 [km / h] is shown.

100 Cruising range extension control system 101 by power running regeneration distribution 101 Optimal torque distribution ratio calculation means 102 Torque distribution control means

Claims (6)

A cruising distance extension control system using power running regeneration distribution for controlling torque distribution between drive wheels, which is used in an automobile having drive wheels driven by motor torque,
The torque distribution ratio that maximizes the overall efficiency that is the sum of the efficiency of all the motors for each vehicle speed relative to the total torque command that is the sum of the torque commands for all the motors driving the drive wheels for each vehicle speed An optimal torque distribution ratio calculating means for calculating an optimal torque distribution ratio that maximizes the total efficiency from the measured vehicle speed and the total torque command input from the driver,
Torque distribution control means for calculating a torque command to be distributed to each of all the motors based on the optimum torque distribution ratio, and individually controlling each of all the motors based on the calculated torque commands. A cruising range extension control system based on power running regeneration distribution.   The cruising distance extension control system according to claim 1, wherein the optimum torque distribution ratio is a torque distribution ratio between front and rear wheels.   The cruising distance extension control system according to claim 1 or 2, wherein the torque command to be distributed is a torque command for performing either power running or regeneration. A cruising distance extension control method using power running regeneration distribution for controlling torque distribution between drive wheels, which is used for an automobile having drive wheels driven by motor torque,
The torque distribution ratio that maximizes the overall efficiency that is the sum of the efficiency of all the motors for each vehicle speed relative to the total torque command that is the sum of the torque commands for all the motors driving the drive wheels for each vehicle speed An optimal torque distribution ratio calculation step for calculating an optimal torque distribution ratio that maximizes the total efficiency from the measured vehicle speed and the total torque command input from the driver,
A torque distribution control step of calculating a torque command to be distributed to each of all the motors based on the optimum torque distribution ratio, and individually controlling each of all the motors based on the calculated torque commands. A cruising distance extension control method by power running regeneration distribution characterized by that.   The cruising distance extension control method by power running regeneration distribution according to claim 4, wherein the optimum torque distribution ratio is a torque distribution ratio between front and rear wheels.   6. The cruising distance extension control method by power running regeneration distribution according to claim 4, wherein the torque command to be distributed is a torque command for performing either power running or regeneration.

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