Method and apparatus for controlling hybrid electric vehicle

• US 9,714,024 B2
• Filed: 12/07/2015
• Issued: 07/25/2017
• Est. Priority Date: 10/06/2015
• Status: Active Grant

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group), Kia Motors Corporation (Kia Corp.)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group), Kia Motors Corporation (Kia Corp.)
• Inventors: Yoon, Dong Pil, Choi, Kwang Hun, Kim, Jungwook, Kim, Tae Soo, Jo, Kyu Hwan, Lee, Jeamun
• Primary Examiner(s): Black, Thomas G
• Assistant Examiner(s): LOUIE, WAE LENNY
• Application Number:
  US14/961,229
• Publication Number:
  US 20170096134A1
• Time in Patent Office: 596 Days
• Field of Search: 701 22, 701400, 701410, 701532, 701541, 180 6526, 180 6527
• CPC Class Codes: B60K 2006/4825 Electric machine connected or connectable to gearbox input shaft
• CPC Class Codes: B60K 6/442 Series-parallel switching type
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/12 using control strategies taking into account route information estimation or calculation of non-directly measurable driving parameters B60W40/00
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 2552/20 Road profile, i.e. the change in elevation or curvature of a plurality of continuous road segments
• CPC Class Codes: B60W 2552/25 Road altitude
• CPC Class Codes: B60W 2554/00 Input parameters relating to objects
• CPC Class Codes: B60W 2555/40 Altitude
• CPC Class Codes: B60W 2556/50 of positioning data, e.g. GPS [Global Positioning System] data
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/1005 : Transmission ratio engaged
• CPC Class Codes: B60W 2710/244 : Charge state
• CPC Class Codes: B60W 50/0097 : Predicting future conditions
• CPC Class Codes: B60Y 2200/92 : Hybrid vehicles
• CPC Class Codes: B60Y 2300/18008 : related to particular drive situations
• CPC Class Codes: B60Y 2300/182 : Selecting between different operative modes, e.g. comfort and performance modes
• CPC Class Codes: G01C 21/34 : Route searching; Route guidance
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/84 : Data processing systems or methods, management, administration
• CPC Class Codes: Y10S 903/93 : Conjoint control of different elements

Abstract

A method and an apparatus for controlling a hybrid electric vehicle are provided. The apparatus includes a navigation device that provides information regarding a gradient, a speed limit, and a traffic speed of a road. An accelerator pedal position detector detects a position of an accelerator pedal and a brake pedal position detector detects a position of a brake pedal. A vehicle speed detector detects a vehicle speed, a state of charge (SOC) detector detects an SOC of a battery, and a gear stage detector detects a gear stage that is currently engaged. A controller operates the hybrid vehicle based on signals of the navigation device, the accelerator pedal position detector, the brake pedal position detector, the vehicle speed detector, the SOC detector, and the gear stage detector.

Claims

1. A method of controlling a hybrid electric vehicle, comprising:

setting, by a controller, a route from a current position of the hybrid electric vehicle toward a destination;

setting, by the controller, a plurality of sections based on information regarding an altitude of the route;

calculating, by the controller, an expected driving force for each section based on a distance for each section, an average effective gradient for each section, and an average effective vehicle speed for each section;

determining, by the controller, an expected gear stage for each section based on the average effective gradient for each section and the average effective vehicle speed for each section;

calculating, by the controller, an expected demand torque of a driver for each section based on the expected driving force for each section and the expected gear stage for each section;

calculating, by the controller, an expected input speed of a transmission for each section based on the average effective vehicle speed for each section and the expected gear stage for each section;

calculating, by the controller, a demand torque of an engine for each section and a demand torque of a motor for each section from the expected demand torque of the driver for each section with reference to an optimal operating point of the engine;

calculating, by the controller, demand power of the motor for each section based on the demand torque of the motor for each section calculated with reference to the optimal operating point of the engine and the expected input speed of the transmission for each section;

calculating, by the controller, a state of charge (SOC) gain for each section based on the demand power of the motor for each section calculated with reference to the optimal operating point of the engine;

calculating, by the controller, a first virtual SOC trend line for each section based on the SOC gain for each section calculated with reference to the optimal operating point of the engine;

calculating, by the controller, an available torque of the motor for each section based on the first virtual SOC trend line and the expected input speed of the transmission for each section;

calculating, by the controller, a limit of the available torque of the motor for each section based on the expected demand torque of the driver for each section and the available torque of the motor for each section;

calculating, by the controller, an available SOC for each section based on the limit of the available torque of the motor for each section;

setting, by the controller, an objective function for minimizing accumulated work of the engine in the plurality of sections;

setting, by the controller, constraint functions of a second virtual SOC trend line to minimize the accumulated work of the engine in the plurality of sections, an expected demand torque of the motor for each section, an expected demand torque of the engine, and accumulated driving work in the plurality of sections;

determining, by the controller, design variables that satisfy the objective function and the constraint functions, wherein the design variables include the second virtual SOC trend line, the expected demand torque of the motor for each section, and the accumulated work of the motor in the plurality of sections;

calculating, by the controller, the expected demand torque of the engine for each section based on the expected demand torque of the driver for each section and the expected demand torque of the motor for each section;

determining, by the controller, an expected driving mode of the hybrid electric vehicle for each section based on the expected demand torque of the driver for each section, the expected demand torque of the engine for each section, and the expected demand torque of the motor for each section;

determining, by the controller, a first threshold line and a second threshold line based on the second virtual SOC trend line, the average effective gradient for each section, and the average effective vehicle speed for each section; and

operating, by the controller, the engine and the motor using the expected driving mode of the hybrid electric vehicle, the first threshold line, and the second threshold line.

2. The method of claim 1, wherein the operating of the engine and the motor using the expected driving mode of the hybrid electric vehicle, the first threshold line, and the second threshold line includes:

determining, by the controller, whether a current SOC of a battery is between the first threshold line and the second threshold line;

when the current SOC of the battery is between the first threshold line and the second threshold line, calculating, by the controller, a demand torque of the motor at a current time based on a difference between an actual demand torque of the driver at the current time and the expected demand torque of the driver in a current section and the expected demand torque of the motor in the current section;

calculating, by the controller, a demand torque of the engine at the current time based on the actual demand torque of the driver at the current time and a demand torque of the motor at the current time; and

operating, by the controller, the engine and the motor based on the demand torque of the engine at the current time and the demand torque of the motor at the current time.

3. The method of claim 2, wherein the operating of the engine and the motor using the expected driving mode of the hybrid electric vehicle, the first threshold line, and the second threshold line includes:

when the current SOC of the battery is less than the first threshold line, calculating, by the controller, a first delta SOC which is a difference between the current SOC of the battery and the first threshold line;

calculating, by the controller, a first correction value based on the first delta SOC; and

performing, by the controller, a charging-oriented control to charge the battery using the first correction value.

4. The method of claim 3, wherein the performing of the charging-oriented control for charging the battery by using the first correction value includes:

calculating, by the controller, a corrected demand torque of the motor at the current time based on the demand torque of the motor at the current time and the first corrections value;

calculating, by the controller, a corrected demand torque of the engine at the current time based on the actual demand torque of the driver at the current time and the corrected demand torque of the motor at the current time; and

operating, by the controller, the engine and the motor based on the corrected demand torque of the engine at the current time and the corrected demand torque of the motor at the current time.

5. The method of claim 2, wherein the operating of the engine and the motor using the expected driving mode of the hybrid electric vehicle, the first threshold value and the second threshold value includes:

when the current SOC is greater than the second threshold line, calculating, by the controller, a second delta SOC which is difference between the current SOC of the battery and the second threshold line;

calculating, by the controller, a second correction value based on the second delta SOC; and

performing, by the controller, discharging-oriented control to discharge the battery using the second correction value.

6. The method of claim 5, wherein the performing of the discharging-oriented control to discharge the battery by using the second correction value includes:

calculating, by the controller, a corrected demand torque of the motor at the current time based on the demand torque of the motor at the current time and the second correction value;

calculating, by the controller, a corrected demand torque of the engine at the current time based on the actual demand torque of the driver at the current time and the corrected demand torque of the motor at the current time; and

operating, by the controller, the engine and the motor based on the corrected demand torque of the engine at the current time and the corrected demand torque of the motor at the current time.

7. The method of claim 1, wherein the average effective gradient for each section is calculated by linearizing altitude by extracting extremums of the altitude.

8. The method of claim 1, wherein the average effective vehicle speed is calculated based on information regarding a speed limit of the route and information regarding a traffic vehicle speed of the route.

9. The method of claim 1, wherein the SOC gain for each section includes a discharging SOC gain for each section and a charging SOC gain for each section,

when the demand torque of the motor for each section calculated with reference to the optimal operating point of the engine is a positive value, the discharging SOC gain for each section is calculated based on the demand power of the motor for each section, discharging efficiency of the motor, the distance for each section, the average effective vehicle speed for each section, and a nominal power of the battery, and

when the demand torque of the motor for each section calculated with reference to the optimal operating point of the engine is a negative value, the charging SOC gain for each section is calculated based on the demand power of the motor for each section, charging efficiency of the motor, the distance for each section, the average effective vehicle speed for each section, and the nominal power of the battery.

10. The method of claim 1, wherein the available torque of the motor for each section includes a discharging available torque of the motor for each section and a charging available torque of the motor for each section,

the discharging available torque of the motor for each section is calculated based on the SOC of the battery at a start point for each section calculated with reference to the optimal operating point of the engine, a minimum limit of the SOC of the battery, the expected input speed of the transmission for each section, discharging efficiency of the motor, the distance for each section, the average effective vehicle speed for each section, and a nominal power of the battery, and

the charging available torque of the motor for each section is calculated based on the SOC of the battery at the start point for each section calculated with reference to the optimal operating point of the engine, a maximum limit of the SOC of the battery, the expected input speed of the transmission, charging efficiency of the motor, the distance for each section, the average effective vehicle speed for each section, and the nominal power of the battery.

11. The method of claim 10, wherein a limit of the available torque of the motor for each section includes a limit of the discharging available torque of the motor for each section and a limit of the charging available torque of the motor for each section,

the limit of the discharging available torque of the motor for each section is calculated based on the discharging available torque of the motor for each section and the expected demand torque of the driver for each section, and

the limit of the charging available torque of the motor for each section is calculated based on the charging available torque of the motor for each section and the expected demand torque of the driver for each section.

12. The method of claim 11, wherein the available SOC for each section includes a discharging available SOC for each section and a charging available SOC for each section,

the discharging available SOC for each section is calculated based on the limit of the discharging available torque of the motor for each section, and

the charging available SOC for each section is calculated based on the limit of the charging available torque of the motor for each section.

13. The method of claim 12, wherein the constraint function of the second virtual SOC trend line is set based on the minimum limit of the SOC of the battery, the discharging available SOC for each section, the charging available SOC for each section, and the maximum limit of the SOC of the battery.

14. The method of claim 12, wherein the constraint function of the expected demand torque of the motor for each section is set based on a minimum torque capable of being output by the motor, the limit of the discharging available torque of the motor for each section, the limit of the charging available torque of the motor for each section, and a maximum torque capable of being output by the motor.

15. An apparatus for controlling a hybrid electric vehicle, comprising:

a navigation device configured to provide information regarding a road gradient, a speed limit, and a traffic speed of a road;

an accelerator pedal position detector configured to detect a position of an accelerator pedal;

a brake pedal position detector configured to detect a position of a brake pedal;

a vehicle speed detector configured to detect a vehicle speed;

a state of charge (SOC) detector configured to detect an SOC of a battery;

a gear stage detector configured to detect a currently engaged gear stage; and

a controller configured to operate the hybrid vehicle based on signals of the navigation device, the accelerator pedal position detector, the brake pedal position detector, the vehicle speed detector, the SOC detector, and the gear stage detector,

wherein the controller is further configured to;

set a route from a current position of the hybrid electric vehicle toward a destination;

set a plurality of sections based on information regarding an altitude of the route;

calculate an expected driving torque for each section based on a distance for each section, an average effective gradient for each section, and an average effective vehicle speed for each section;

determine an expected gear stage for each section based on the average effective gradient for each section and the average effective vehicle speed for each section;

calculate an expected demand torque of a driver for each section based on the expected driving torque for each section and the expected gear stage for each section;

calculate an expected input speed of a transmission for each section based on the average effective vehicle speed for each section and the expected gear stage for each section;

calculate a demand torque of an engine for each section and a demand torque of a motor for each section from the expected demand torque of the driver for each section with reference to an optimal operating point of the engine;

calculate a demand power of the motor for each section based on the demand torque of the motor for each section calculated with reference to the optimal operating point of the engine and the expected input speed of the transmission for each section;

calculate a state of charge (SOC) gain for each section based on the demand power of the motor for each section calculated with reference to the optimal operating point of the engine;

calculate a first virtual SOC trend line for each section based on the SOC gain for each section calculated with reference to the optimal operating point of the engine;

calculate an available torque of the motor for each section based on the first virtual SOC trend line and the expected input speed of the transmission for each section;

calculate a limit of the available torque of the motor for each section based on the expected demand torque of the driver for each section and the available torque of the motor for each section;

calculate an available SOC for each section based on the limit of the available torque of the motor for each section;

set an objective function to minimize accumulated work of the engine in the plurality of sections;

set constraint functions of a second virtual SOC trend line to minimize the accumulated work of the engine in the plurality of sections, an expected demand torque of the motor for each section, an expected demand torque of the engine, and accumulated driving work in the plurality of sections;

determine design variables that satisfy the objective function and the constraint functions, wherein the design variables includes the second virtual SOC trend line, the expected demand torque of the motor for each section, and the accumulated work of the motor in the plurality of sections;

calculate the expected demand torque of the engine for each section based on the expected demand torque of the driver for each section and the expected demand torque of the motor for each section;

determine an expected driving mode of the hybrid electric vehicle for each section based on the expected demand torque of the driver for each section, the expected demand torque of the engine for each section, and the expected demand torque of the motor for each section;

determine a first threshold line and a second threshold line based on the second virtual SOC trend line, the average effective gradient for each section, and the average effective vehicle speed for each section; and

operate the engine and the motor by using the expected driving mode of the hybrid electric vehicle, the first threshold line, and the second threshold line.

16. The apparatus of claim 15, wherein in the operation of the engine and the motor using the expected driving mode of the hybrid electric vehicle, the first threshold line, and the second threshold line the controller is further configured to:

determine whether a current SOC of a battery is between the first threshold line and the second threshold line;

when the current SOC of the battery is between the first threshold line and the second threshold line, calculate a demand torque of the motor at a current time based on a difference between an actual demand torque of the driver at the current time and the expected demand torque of the driver in a current section and the expected demand torque of the motor in the current section;

calculate a demand torque of the engine at the current time based on the actual demand torque of the driver at the current time and a demand torque of the motor at the current time; and

operate the engine and the motor based on the demand torque of the engine at the current time and the demand torque of the motor at the current time.

17. The apparatus of claim 16, wherein in the operation of the engine and the motor using the expected driving mode of the hybrid electric vehicle, the first threshold line, and the second threshold line the controller is further configured to:

when the current SOC of the battery is less than the first threshold line, calculate a first delta SOC which is a difference between the current SOC of the battery and the first threshold line;

calculate a first correction value based on the first delta SOC; and

perform a charging-oriented control to charge the battery using the first correction value.

18. The apparatus of claim 17, wherein in the performing of the charging-oriented control for charging the battery by using the first correction value the controller is further configured to:

calculate a corrected demand torque of the motor at the current time based on the demand torque of the motor at the current time and the first corrections value;

calculate a corrected demand torque of the engine at the current time based on the actual demand torque of the driver at the current time and the corrected demand torque of the motor at the current time; and

operate the engine and the motor based on the corrected demand torque of the engine at the current time and the corrected demand torque of the motor at the current time.