HEV Motor Torque Compensation During Power-On Upshifts
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Solution Overview
Problem
Conventional Hybrid Electric Vehicles (HEVs) face challenges in reducing acceleration loss during quick acceleration due to the disengagement of power transmission during gear shifts, particularly in high APS value scenarios, where additional torque from the Hybrid Starter Generator (HSG) is difficult to obtain.
Innovation Solution
A motor control method for HEVs that includes a first motor directly connected to the engine and a second motor at the transmission input, with a hybrid control unit determining a compensation torque to compensate for acceleration loss by controlling the first motor's torque based on requested torque, engine torque, second motor torque, and transmission information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If power transmission is disengaged during gear shifts in conventional HEVs, then gear shifting is achieved, but acceleration loss occurs due to momentary loss of driving power
Solution Approach 1:
The control device determines a compensation torque before the gear shift occurs and controls the first motor to output this torque during the shift process. This preliminary action ensures that driving power is maintained even when the transmission is disengaged, preventing acceleration loss during gear transitions.
Solution Approach 2:
The first motor acts as an intermediary power source between the engine and the transmission. By controlling the first motor to output compensation torque during gear shifts, it mediates the power transmission gap that occurs when the transmission disengages, maintaining continuous driving power to the wheels.
2Power
If the HSG is used to generate additional torque during quick acceleration, then acceleration loss may be reduced, but the HSG cannot operate effectively at high rotational speeds required for quick acceleration
Solution Approach 1:
The powertrain is segmented into two separate motor systems: the second motor (HSG) connected to the engine via pulleys for normal operation, and the first motor directly connected to the transmission for high-speed torque compensation. This segmentation allows each motor to operate in its optimal speed range, with the first motor specifically handling high-speed acceleration scenarios where the HSG would be ineffective.
Data Source
AI summary
A hybrid vehicle (HEV) provides an improved sensation of acceleration. An example method for controlling an engine of an HEV which includes a first motor directly connected to an engine and a second motor located at an input side of a transmission, may include determining a requested torque, determining a compensation torque for compensating an acceleration loss in a shift process based on the requested torque, a torque of the second motor, a torque of the engine and information on the shift, determining an available torque of the first motor, and determining a final torque of the first motor based on the compensation torque and the available torque.