Mild Hybrid Motor Control for Using Excess Recuperation Energy
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Solution Overview
Problem
Mild hybrid vehicles face challenges in optimizing fuel efficiency due to limitations in the use of electric machines for both starting and recuperation, with existing systems not effectively utilizing excess electrical energy during driving to support the internal combustion engine.
Innovation Solution
An operating method that determines suitable driving situations for motor operation of the electric machine based on current and past vehicle data, including stop duration, travel time, and average deceleration, to relieve the load on the internal combustion engine by using excess electrical energy for motor operation, thereby enhancing fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the electric machine is used as a starter generator for automatic stop-start operation and for recuperation, then the vehicle can reduce fuel consumption and recover braking energy, but the electric machine cannot provide motor assistance to the combustion engine during driving
Solution Approach 1:
The electric machine is designed to perform multiple functions: starter generator operation for engine starting, recuperation mode for energy recovery during braking, and motor operation for providing torque assistance during driving. This multi-functionality resolves the contradiction by enabling the same electric machine to both reduce fuel consumption through stop-start and recuperation while also providing motor assistance during driving phases.
2Loss of energy
If the electric machine operates in recuperation mode to generate electrical energy, then kinetic energy is converted to electrical energy for storage, but excess electrical energy cannot be utilized to support the combustion engine during driving
Solution Approach 1:
The system enables continuous useful action by seamlessly transitioning between recuperation mode (converting kinetic energy to electrical energy during braking) and motor operation mode (consuming stored electrical energy to provide torque assistance during driving). This continuity ensures that electrical energy is continuously utilized rather than remaining excess, thereby resolving the contradiction between energy recovery and energy utilization.
3Productivity
If the electric machine provides motor operation to assist the combustion engine, then fuel efficiency improves, but the ability to recuperate and store energy for future use is reduced
Solution Approach 1:
The control system dynamically adjusts the operating mode of the electric machine based on real-time vehicle conditions, state of charge of the energy storage device, and driving situation. The system can switch between motor operation (when energy is available and fuel efficiency is prioritized) and recuperation mode (when energy storage capacity needs replenishment). This dynamic adaptation resolves the contradiction by optimizing the balance between fuel efficiency gains from motor operation and maintaining sufficient energy storage capacity for future recuperation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces fuel consumption by utilizing excess electrical energy for motor operation during driving, ensuring efficient energy use and maintaining the ability to recuperate energy during stops, thus improving the overall fuel economy of the vehicle.
Implementation Method 1
the electric machine (10) ... to generate electrical energy in a recuperation mode
Implementation Method 2
motor operation of the electric machine (10) ... to generate a torque with motor operation of the electric machine in order to relieve or assist the internal combustion engine
Implementation Method 3
an energy storage device (9), which is designed to supply the electric machine (10) with electrical energy at least temporarily and to store energy generated by the electric machine (10)
Data Source
Figure 1
Figure 2
AI summary
The invention relates to an operating method for controlling the motor operation of an electric machine capable of both motor and generator operation in a mild hybrid drive of a motor vehicle, wherein the electric machine is configured to drive an internal combustion engine of the motor vehicle at least intermittently and to generate electrical energy in recuperation mode. The invention further relates to a device configured to execute the operating method. According to the operating method, a decision as to whether and/or at what power the electric machine is operated in motor mode during driving in order to relieve the internal combustion engine of the motor vehicle by providing motor torque is determined depending on the instantaneous values of at least one operating parameter (21) of the motor vehicle and depending on past driving data (22).In this way, the fuel savings of the mild hybrid system can be increased by using energy that would otherwise be unusable.