Hybrid Vehicle Motor Countertorque Control for Torque Fluctuation
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Solution Overview
Problem
Conventional hybrid vehicle driving force control methods suffer from energy efficiency deterioration due to high-frequency motor operation required to suppress engine torque pulsation, leading to increased energy loss and reduced fuel economy.
Innovation Solution
A driving force control method where the electric motor's countertorque is adjusted based on the average torque output and engine speed, allowing for effective absorption of torque fluctuations while minimizing energy loss by optimizing countertorque amplitude and control gain settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the motor is controlled to output positive pulsation torque at high frequency to suppress engine torque fluctuation, then vibration suppression performance is improved, but energy efficiency deteriorates due to large losses from high-frequency electric power input and output
Solution Approach 1:
The patent changes the control parameters by adjusting the amplitude and frequency of the pulsation torque based on engine operating conditions (torque and speed). The control amount is dynamically adjusted according to engine torque Ta and engine speed Ne, allowing the system to suppress vibrations effectively while minimizing energy losses by adapting the counter-torque magnitude to actual engine conditions rather than operating at fixed high frequency
Solution Approach 2:
The system dynamically adjusts the motor's pulsation torque output based on real-time engine operating conditions. The control amount determination unit calculates the required pulsation torque amplitude and frequency based on current engine torque and speed, enabling the system to adapt its vibration suppression action to match actual engine conditions, thereby reducing unnecessary energy consumption while maintaining effective vibration control
2Speed
If the inertia of the engine is reduced to shorten shifting time, then drivability is improved, but the ability to absorb torque fluctuation without additional components is reduced
Solution Approach 1:
The patent introduces the electric motor as an intermediary device between the engine and the transmission system. The motor acts as a mediator that absorbs and compensates for engine torque fluctuations through controlled pulsation torque output, allowing the engine to operate with reduced inertia for faster shifting while the motor handles the torque stabilization function
Solution Approach 2:
The electric motor performs multiple functions: it provides auxiliary propulsion, enables regenerative braking, and serves as a vibration suppression device through pulsation torque control. This multi-functionality allows the system to reduce engine inertia for improved shifting performance while the motor compensates for torque fluctuations, eliminating the need for additional dedicated vibration control components
3Loss of energy
If cylinder deactivation is implemented to improve fuel economy, then fuel consumption is reduced, but torque fluctuation increases requiring enhanced absorption capability
Solution Approach 1:
The system continuously monitors engine torque and speed to detect torque fluctuations caused by cylinder deactivation. The control amount determination unit uses this feedback information to calculate and adjust the required pulsation torque amplitude in real-time, enabling the motor to effectively counteract the increased torque fluctuations while maintaining the fuel economy benefits of cylinder deactivation
Solution Approach 2:
The patent adjusts the control parameters of the pulsation torque based on engine operating conditions including cylinder deactivation states. When cylinder deactivation is active, the system modifies the amplitude and frequency characteristics of the counter-torque to match the altered torque fluctuation patterns, enabling effective vibration suppression across different engine operating modes while preserving fuel economy improvements
Data Source
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AI summary
Provided are a driving force control method and device for a hybrid vehicle, each capable of effectively absorbing torque fluctuation of an engine while suppressing deterioration in energy efficiency. The driving force control device for a hybrid vehicle comprises a PCM (14) configured to: estimate an average torque output by an engine (2); estimate a torque fluctuation component of the torque output by the engine; set a countertorque for suppressing the estimated torque fluctuation component; and control an electric motor to output the set countertorque, wherein the PCM is operable, under a condition that an engine speed is constant, to set the countertorque such that, as the average torque output by the engine becomes larger, the absolute value of the countertorque becomes larger.