Hybrid Vehicle Mode Switching Controller
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Solution Overview
Problem
Hybrid electric vehicles face challenges in efficiently switching between travel modes to prevent battery state of charge from falling below a certain level, leading to increased fuel consumption and potential battery depletion, especially at low speeds.
Innovation Solution
A traveling mode switching controller that includes a state-of-charge detection unit, driver request output detection unit, and a correction unit to calculate a vehicle request output, with a switching control unit that sets a low output threshold value as the battery state of charge decreases, and adjusts the time constant for damping processes based on battery state, optimizing the transition from EV mode to series mode to prevent battery depletion while minimizing engine activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the EV mode is switched to the other mode (series mode) in good time to prevent battery state of charge from falling below the allowable range, then the battery state of charge is maintained within the allowable range, but fuel consumption deteriorates
Solution Approach 1:
The system performs preliminary action by detecting the state of charge in advance and predicting future battery status. When the state of charge is high, the system proactively switches to EV mode earlier than conventional systems, maintaining battery levels within the allowable range while avoiding unnecessary engine activation. This predictive approach prevents battery depletion without causing excessive fuel consumption.
2Use of energy by moving object
If the EV mode is maintained as long as possible to improve fuel consumption, then fuel consumption improves, but the battery state of charge may fall below the allowable range
Solution Approach 1:
The system implements feedback control by continuously monitoring the state of charge and using this information to dynamically adjust mode switching decisions. The state of charge detection unit provides real-time feedback to the control unit, which then determines the optimal switching timing. This feedback mechanism ensures that the EV mode is maintained as long as possible for fuel efficiency while guaranteeing that the battery state of charge remains within the allowable range.
3Use of energy by moving object
If the output threshold value is set high to maintain EV mode longer, then fuel consumption improves, but the battery state of charge may fall below the allowable range at low vehicle speeds
Solution Approach 1:
The system applies dynamics by making the output threshold value adjustable rather than fixed. The control unit dynamically changes the output threshold value based on the detected state of charge and vehicle operating conditions. When the state of charge is high, the threshold is set higher to maintain EV mode longer for fuel savings. When the state of charge is low or vehicle speed is low, the threshold is adjusted downward to ensure the battery state of charge remains within the allowable range. This dynamic adjustment resolves the contradiction between fuel efficiency and battery maintenance.
Data Source
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AI summary
A traveling mode switching controller of a hybrid electric vehicle has a state-of-charge detection unit (11a); a driver request output detection unit (20); a correction unit (20a); and a switching control unit (20) for controlling a switch from a first traveling mode to a second traveling mode when a vehicle request output exceeds an output threshold value. In the first traveling mode, an engine (2) is deactivated and a drive motor (4, 6) is activated. In the second traveling mode, drive wheels 3, 5) are actuated by means of driving power of the engine (2), or a generator (9) connected to the engine (2) is activated to generate electric power to activate the drive motor (4, 6) to actuate the drive wheels (3, 5). The switching control unit (20) sets the output threshold value low as the state of charge decreases, thereby changing conditions for switching the first traveling mode to the second traveling mode.