Hybrid Vehicle Voltage Control for Engine Start Reliability
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Solution Overview
Problem
Conventional engine start control systems for hybrid vehicles rely on 'several seconds value' power calculations, which result in underestimating the engine's ability to meet instantaneous power demands, leading to reduced reliability and prolonged engine start times due to excessive target rotation speed decreases.
Innovation Solution
The control system uses a voltage control unit to manage battery output based on a first power value within the battery's limit voltage, allowing for efficient power delivery to the inverter, which controls the electric motor to start the internal combustion engine effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the power value (several seconds value) is used for comparison with the required power, then the battery output can be controlled based on stable power output capability, but the target rotation speed of motor decreases excessively leading to reduced engine start reliability
Solution Approach 1:
The control method dynamically switches between two power value calculation approaches: using the several seconds value for stable power output control during normal operation, and using the instantaneous value for engine start control when high power is needed. This dynamic adaptation resolves the contradiction by selecting the appropriate control strategy based on the operational state.
Solution Approach 2:
The invention changes the parameter used for power control based on the operational context. For engine start operations, it switches to using the instantaneous power value (which allows higher motor rotation speed) instead of the several seconds power value, thereby maintaining engine start reliability while still ensuring stable power output during normal operation.
2Duration of action of stationary object
If the power value (several seconds value) is used for comparison with the required power, then the battery can maintain stable output for predetermined time, but the time required for engine start increases
Solution Approach 1:
The control system dynamically adjusts the power value calculation method based on the operational state. During engine start, it uses the instantaneous power value that reflects momentary output capability, thereby reducing engine start time. During normal operation, it switches to the several seconds power value to maintain stable power output for predetermined time periods.
Solution Approach 2:
The system performs preliminary assessment of the operational state to determine which power value calculation method to use. By identifying engine start conditions in advance and switching to the instantaneous power value approach, the system prepares for high-power delivery needs before they occur, reducing overall engine start time.
3Power
If the target rotation speed of motor is decreased based on the power value (several seconds value), then the battery power output is controlled within stable limits, but the engine start completion time is prolonged
Solution Approach 1:
The invention changes the control parameter from the several seconds power value to the instantaneous power value during engine start operations. This parameter change allows the motor rotation speed to be set based on the battery's momentary output capability rather than its average stable output capability, thereby increasing engine start speed while maintaining power output control through the instantaneous value approach.
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 enhances the reliability of engine starts by ensuring the battery supplies sufficient power within safe voltage limits, preventing over-discharge and maintaining efficient energy use, thus reducing the time required for engine start completion.
Implementation Method 1
an inverter (35) for controlling the electric motor
Data Source
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AI summary
Provided is a control system for controlling a hybrid vehicle including: an internal combustion engine; an electric motor for starting the internal combustion engine; an inverter (35) for controlling the electric motor; a clutch for selectively connecting and disconnecting power transmission between the internal combustion engine and the electric motor; and a battery (30) for supplying power to the electric motor. The control device includes: a voltage detection unit for detecting the voltage of the battery (30); a voltage control unit for controlling the output of the battery (30) in accordance with a first power value currently available within the range of limit voltages of the battery (30); and an internal combustion engine starting unit for engaging the clutch to start engine (10) while controlling the inverter (35) in accordance with the output from the battery (30) that in turn is controlled by the voltage control unit.