Electrical Machine Oscillation to Free Regenerative Braking Capacity
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Solution Overview
Problem
The ability to use regenerative braking is limited by the storage capacity of the energy storage system, leading to reduced braking power and increased wear on auxiliary brakes, and predictive speed reduction can disturb drivers and increase operational costs.
Innovation Solution
A method involving disconnecting the electrical machine from the drive wheels and oscillating it between a first and second rotational speed to consume energy from the energy storage system, utilizing its inertia to generate power and heat, thereby draining the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the energy storage system is charged to maximum capacity, then regenerative braking power is limited, but braking performance deteriorates when capacity is full
Solution Approach 1:
The control arrangement performs preliminary draining of the energy storage system before an upcoming braking event by controlling the electrical machine to oscillate between first and second rotational speeds. This advance action ensures that the energy storage system has sufficient capacity to accept regenerative braking energy when the braking event occurs, preventing the loss of braking power that would occur if the system were already at maximum capacity.
2Power
If predictive speed reduction is applied, then regenerative braking power requirement is reduced, but driver comfort and operational efficiency deteriorate
Solution Approach 1:
Instead of reducing vehicle speed to lower regenerative braking power requirements, the system allows the energy storage system to service itself by draining through electrical machine oscillation. This self-service approach maintains normal vehicle speed and driver comfort while preparing the energy storage system to have sufficient capacity for the upcoming braking event.
3Reliability
If service brakes are used to compensate for insufficient regenerative braking power, then braking reliability is maintained, but brake wear and overheating increase
Solution Approach 1:
The control arrangement performs preliminary draining of the energy storage system before the braking event, ensuring that sufficient capacity is available to accept regenerative braking energy. This preliminary action enables the system to rely more heavily on regenerative braking during the actual braking event, thereby reducing the need to use service brakes and minimizing brake wear and overheating.
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 method enhances regenerative braking power by discharging the energy storage system, reducing the need for auxiliary brakes and improving road safety while optimizing energy use.
Implementation Method 1
utilizing its inertia to generate power and heat, thereby draining the system
Implementation Method 2
utilizing its inertia to generate power and heat, thereby draining the system
Data Source
Figure 1~3
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Figure 6~7
AI summary
A control arrangement (100) and a method for controlling an electrical machine (3, 3') of a vehicle (1), wherein said machine (3, 3') is configured to provide propulsion power to one or more drive wheels (8, 8') of the vehicle (1) and the vehicle (1) comprises an energy storage system (20) configured to power the electrical machine (3, 3'). The method comprises a step of, in response to a request for draining of the energy storage system (20), disconnecting the electrical machine (3, 3') from the one or more drive wheels (8, 8'). The method further comprises a step of controlling the electrical machine (3, 3') to oscillate between a first rotational speed (ω1) and a second rotational speed (ω2) to thereby consume energy from the energy storage system (20).