Driving force control device for electric vehicle

• US 9,174,549 B2
• Filed: 06/22/2011
• Issued: 11/03/2015
• Est. Priority Date: 06/30/2010
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Ichinose, Masanori, Yasuda, Tomohiko, Satou, Takayuki
• Primary Examiner(s): To, Tuan C.
• Assistant Examiner(s): Kan, Yuri
• Application Number:
  US13/806,808
• Publication Number:
  US 20130103244A1
• Time in Patent Office: 1,595 Days
• Field of Search: 701/22, 701/70, 180/65.1, 290/4.R, 303/20, 303/146, 303/15, 303/113.5, 318/432, 318/139, 318/802, 187/290, 477/3
• US Class Current: 1/1
• CPC Class Codes: B60K 17/356 having fluid or electric motor, for driving one or more wheels disposition of motor in, or adjacent to, traction wheel B60K7/00
• CPC Class Codes: B60K 7/0007 the motor being electric
• CPC Class Codes: B60L 15/10 for automatic control superimposed on human control to limit the acceleration of the vehicle, e.g. to prevent excessive motor current electric devices for safety purposes B60L3/00
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 15/2036 Electric differentials, e.g. for supporting steering vehicles
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 2220/46 Wheel motors, i.e. motor connected to only one wheel
• CPC Class Codes: B60L 3/06 Limiting the traction current under mechanical overload conditions
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/105 Output torque
• CPC Class Codes: B60W 2720/30 Wheel torque
• CPC Class Codes: B60W 30/18172 Preventing, or responsive to skidding of wheels
• CPC Class Codes: B60Y 2200/142 Heavy duty trucks
• CPC Class Codes: B60Y 2200/20 Off-Road Vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

Disclosed is a driving force control device that includes a determination section (12), a driving force command value calculation section (13), and a command value output section (14). The determination section (12) determines whether each of a plurality of motors (106), which independently drive a plurality of wheels (107), can be operated within a desired operating range when driven by a target driving force calculated for each of the motors (106). The driving force command value calculation section (13) adjusts the distribution of driving force for each of the motors in accordance with the target driving force for each of the motors and with the operating status of each of the motors and calculates an actual driving force command value for each of the motors for the purpose of operating each of the motors within the desired operating range if the determination means determines that each of the motors cannot be operated within the desired operating range. The command value output section (14) outputs the driving force command value to each of a plurality of inverters (105). Therefore, a target vehicle motion can be maximally realized while appropriately maintaining the drive status of each of the motors.

Claims

1. A driving force control processor for an electric vehicle having a plurality of motors, which independently drive a plurality of wheels, and a plurality of inverters, which control a drive current for each of the motors in accordance with a driving force command value, the driving force control processor comprising:

target driving force calculation means configured to calculate and output a target driving force for each of the motors in accordance with a vehicle operation performed by an operator of the vehicle or with the running status of the vehicle;

determination means configured to receive the target driving force from the target driving force calculation means, and to determine and output whether the motors engaged in power running and in regeneration would coexist if each of the motors is driven by the target driving force;

driving force command value calculation means configured to receive the output from the determination means, and if the determination means determines that the motors engaged in power running and in regeneration coexist, to adjust the distribution of driving force for each of the motors in accordance with the target driving force for each of the motors so that all of the motors are engaged in either power running or regeneration, and to calculate and output an actual driving force command value for each of the motors; and

command value output means configured to receive the actual driving force command value for each of the motors and to output the actual driving force command value to each of the inverters for the purpose of operating each of the motors,

wherein the motors drive the left- and right-side wheels of the electric vehicle; and

wherein if the determination means determines that one of the two motors driving the left- and right-side wheels is engaged in power running whereas the other motor is engaged in regeneration, the driving force command value calculation means is configured to compare the absolute values of target driving forces for the two motors, invert the sign of the target driving force for the motor having the smaller absolute value, add the resulting target driving force to the target driving force for the other motor to calculate the actual driving force command value for the other motor, and calculate the actual driving force command value for the motor having the smaller absolute value by changing the target driving force for the motor having the smaller absolute value to zero.

3. The driving force control processor according to claim 1,

wherein, when the determination means determines that one of the two motors driving the left- and right-side wheels is engaged in power running whereas the other motor is engaged in regeneration, the driving force command value calculation means is configured to determine the sum of the target driving forces for the two motors, and

a) if the sign of the sum is positive, then the driving force command value calculation means is configured to compare the absolute values of the target driving forces for the two motors, to invert the sign of the target driving force for the motor having the smaller absolute value, to add the resulting target driving force to the target driving force for the other motor to calculate the actual driving force command value for the other motor, and to calculate the actual driving force command value for the motor having the smaller absolute value by changing the target driving force for the motor having the smaller absolute value to zero, and

b) if the sign of the sum is negative, then the driving force command value calculation means is configured to calculate the actual driving force command value for the motor engaged in regeneration by subtracting a value equivalent to the target driving force for the motor engaged in power running from the target driving force for the motor engaged in regeneration, and to calculate the actual driving force command value for the motor engaged in power running by changing the target driving force for the motor engaged in power running to zero.

2. A driving force control processor for an electric vehicle having a plurality of motors, which independently drive a plurality of wheels, and a plurality of inverters, which control a drive current for each of the motors in accordance with a driving force command value, the driving force control processor comprising:

target driving force calculation means configured to calculate and output a target driving force for each of the motors in accordance with a vehicle operation performed by an operator of the vehicle or with the running status of the vehicle;

determination means configured to receive the target driving force from the target driving force calculation means, and to determine and output whether the motors engaged in power running and in regeneration would coexist if each of the motors is driven by the target driving force;

driving force command value calculation means configured to receive the output from the determination means, and if the determination means determines that the motors engaged in power running and in regeneration coexist, to adjust the distribution of driving force for each of the motors in accordance with the target driving force for each of the motors so that all the motors are engaged in either power running or regeneration, and to calculate an actual driving force command value for each of the motors; and

command value output means configured to receive the actual driving force command value for each of the motors and to output the actual driving force command value to each of the inverters for the purpose of operating each of the motors,

wherein the motors drive the left- and right-side wheels of the electric vehicle; and

wherein, if the determination means determines that one of the two motors driving the left- and right-side wheels is engaged in power running whereas the other motor is engaged in regeneration, the driving force command value calculation means is configured to calculate the actual driving force command value for the motor engaged in regeneration by subtracting a value equivalent to the target driving force for the motor engaged in power running from the target driving force for the motor engaged in regeneration, and to calculate the actual driving force command value for the motor engaged in power running by changing the target driving force for the motor engaged in power running to zero.

4. A driving force control processor for an electric vehicle having a plurality of motors, which independently drive a plurality of wheels, a plurality of inverters, which control a drive current for each of the motors in accordance with a driving force command value, and a plurality of braking devices, which independently apply a braking torque to each of the wheels, the driving force control processor comprising:

target driving force calculation means configured to calculate and output a target driving force for each of the motors in accordance with a vehicle operation performed by an occupant of the vehicle or with the running status of the vehicle;

determination means configured to receive the target driving force from the target driving force calculation means, and to determine whether the motors engaged in power running and in regeneration would coexist if each of the motors is driven by the target driving force;

driving force command value calculation means configured to receive the output from the determination means, and if the determination means determines that the motors engaged in power running and in regeneration coexist, to calculate the actual driving force command value for a motor engaged in power running in accordance with the target driving force for the motor engaged in power running, to calculate the actual driving force command value for a motor engaged in regeneration by changing the target driving force for the motor engaged in regeneration to zero, to calculate actual driving force command values for the braking devices in order to permit the braking devices to generate a braking torque equivalent to the target driving force for the motor engaged in regeneration, and to output the actual driving force command values; and

command value output means configured to receive the actual driving force command values for the purpose of operating each of the motors and outputs the actual driving force command value to each of the inverters and to output the actual driving force command value to each of the braking devices.