Method for determining optimal operating point for hybrid electric vehicle

• US 10,562,515 B2
• Filed: 05/31/2017
• Issued: 02/18/2020
• Est. Priority Date: 11/16/2016
• Status: Active Grant

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group), Kia Motors Corporation (Kia Corp.)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Inventors: Oh, Ji Won, Eo, Jeong Soo, Kim, Sung Jae
• Primary Examiner(s): Weber, Tamara L
• Application Number:
  US15/609,913
• Publication Number:
  US 20180134273A1
• Time in Patent Office: 993 Days
• Field of Search: None
• CPC Class Codes: B60K 6/48 Parallel type
• 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 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/11 using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• 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 2050/0041 of the drive line
• CPC Class Codes: B60W 2050/0075 Automatic parameter input, automatic initialising or calibrating means
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2556/10 Historical data
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2710/081 Speed
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 30/188 Controlling power parameters of the driveline, e.g. determining the required power
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/84 : Data processing systems or methods, management, administration

Abstract

The present disclosure provides a method of determining an optimal operating point of a hybrid electric vehicle. The method includes: determining demand torque, comparing the demand torque and an engine torque reference value obtained from an optimal operating line to determine a determined mode where the determined mode is a charging mode or a discharging mode, determining a plurality of candidate points comprising a combination of an engine operating point satisfying the demand torque and a motor operating point corresponding to the engine operating point in the determined mode, calculating system efficiency during charging using charging efficiency of each candidate point of the plurality of candidate points and discharging efficiency during previous driving when the determined mode is a charging mode, and determining a candidate point with highest system efficiency during charging as an optimal operating point.

Claims

1. A method of determining an optimal operating point of a hybrid electric vehicle, the method comprising:

determining, by a controller, a demand torque of a driver by collecting vehicle driving information from an acceleration pedal sensor (APS), a brake pedal sensor (BPS), and vehicle state information including a gear stage, a vehicle speed, an engine velocity (rpm), a battery state of charge (SOC);

comparing, by the controller, the demand torque and an engine torque reference value obtained from an optimal operating line to determine a determined mode, wherein the determined mode is a charging mode or a discharging mode;

determining, by the controller, a plurality of candidate points in the determined mode, wherein each candidate point comprises a combination of an engine operating point satisfying the demand torque and a motor operating point corresponding to the engine operating point;

when the determined mode is a charging mode, calculating, by the controller, a system efficiency during charging based on a charging efficiency of each candidate point of the plurality of candidate points and an average discharging efficiency during previous driving;

when the determined mode is a discharging mode, calculating, by the controller, a system efficiency during discharging based on an average discharging efficiency of each candidate point of the plurality of candidate points and an average charging efficiency during previous driving;

determining, by the controller, the optimal operating point, wherein the optimal operating point is the candidate point with the highest system efficiency during charging or discharging; and

controlling, by the controller, an operation of the engine and a motor based on the determined optimal operating point.

2. The method of claim 1, wherein the system efficiency during discharging is based on an engine output and a motor output of each candidate point of the plurality of candidate points, a discharging efficiency, the charging efficiency during previous driving, and an engine efficiency.

3. The method of claim 2, wherein the system efficiency during discharging is acquired according to Equation 2 below:

4. The method of claim 1, wherein the average charging efficiency is obtained by averaging efficiencies during charging for a recent predetermined amount of time.

5. The method of claim 1, wherein the system efficiency during discharging is acquired based on a demand output, the engine output and the motor output of each candidate point of the plurality of candidate points, the discharging efficiency, the charging efficiency during previous driving, and the engine efficiency, wherein the demand output is calculated from the demand torque.

6. The method of claim 1, wherein the system efficiency during charging is acquired based on the engine output and the motor output of each candidate point of the plurality of candidate points, a charging efficiency, the discharging efficiency during previous driving, and the engine efficiency.

7. The method of claim 6, wherein the system efficiency during charging is acquired according to Equation 1 below:

8. The method of claim 1, wherein the system efficiency during charging is acquired based on the demand output, the engine output and the motor output of each candidate point of the plurality of candidate points, the charging efficiency, the discharging efficiency during previous driving, and the engine efficiency, wherein the demand output is calculated from the demand torque.

9. The method of claim 1, wherein the average discharging efficiency is obtained by averaging efficiencies during discharging for a recent predetermined amount of time.