Hybrid Vehicle Controller Using Route Profiles for Battery Management
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Solution Overview
Problem
Existing hybrid vehicle systems are inefficient in managing the state of charge of the traction battery, particularly after recuperation phases, as they fail to anticipate and utilize energy effectively based on vehicle speed and route profiles, leading to unnecessary battery discharge and increased electrical losses.
Innovation Solution
A method that uses anticipated vehicle speed and route profiles to determine a setpoint for the state of charge, keeping the electric motor power constant and adjusting it within defined limit values to optimize battery usage, thereby reducing electrical losses and enhancing energy absorption during braking maneuvers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the state of charge of the traction battery is rapidly reduced after recuperation phases, then the battery can provide power quickly, but electrical losses in the electric motor and battery increase
Solution Approach 1:
The control unit calculates the anticipated vehicle speed and route profile in advance to determine an optimal target value for the state of charge before rapid discharge is needed. This preliminary planning allows the system to prepare the battery state strategically, reducing the need for rapid discharge and thereby minimizing electrical losses while still meeting future power demands.
Solution Approach 2:
The system dynamically adjusts the target value for the state of charge based on real-time conditions including anticipated vehicle speed, route profile, and current battery state. This dynamic adjustment optimizes the discharge rate to match actual vehicle needs, preventing unnecessarily rapid discharge that would cause increased electrical losses.
2Reliability
If the power of the electric motor is frequently adjusted to maintain state of charge limits, then the state of charge remains within optimal ranges, but the duration of constant power operation is reduced
Solution Approach 1:
By calculating the anticipated vehicle speed and route profile in advance, the system determines a target state of charge value that anticipates future power needs. This allows the electric motor to operate at constant power for longer periods, adjusting the state of charge proactively rather than reactively, thereby extending constant power duration while maintaining reliability.
Solution Approach 2:
The control unit continuously monitors the actual state of charge and compares it with the target value derived from anticipated conditions. This feedback mechanism allows for minimal, targeted adjustments to maintain state of charge within optimal ranges while maximizing constant power operation duration.
3Reliability
If the upper limit value for state of charge is reduced at higher vehicle speeds, then more energy can be absorbed during unforeseen braking, but the available energy capacity at normal speeds is reduced
Solution Approach 1:
The upper limit value for state of charge is dynamically adjusted based on anticipated vehicle speed. At higher speeds where braking energy recovery opportunities are more likely, the upper limit is reduced to create headroom for absorbing regenerative energy. At lower speeds, the upper limit increases to maximize available energy capacity. This dynamic adaptation resolves the contradiction by optimizing the parameter for current operating conditions.
Solution Approach 2:
The system changes the state of charge limit parameter based on vehicle speed and anticipated route profile. This parameter adaptation allows the battery management system to optimize between available energy capacity and energy absorption capability depending on the driving context, resolving the trade-off between these two opposing requirements.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3
AI summary
The invention relates to a method for operating a vehicle (1), to a controller (5), and to a vehicle (1) having an internal combustion engine (2), at least one electric motor (3), a traction battery (4), and a controller (5). An expected vehicle speed (v) and an expected roadway profile (x) are used in order to determine a resulting change in the charge state (SoC) of the traction battery (4) and define a target value for the charge state (SoCp). The target value for the charge state (SoCp) is used to actuate the electric motor (3) and/or the internal combustion engine (2), wherein an output (PE) of the electric motor (3) is kept constant at least temporarily.