Engine Start Control for Series Hybrid Vehicles
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Solution Overview
Problem
Series hybrid vehicles experience engine response delays when the actual current level exceeds the allowable discharge capacity, leading to inconsistent power delivery and driver discomfort, as existing solutions do not adequately address the delay in engine start procedures.
Innovation Solution
An engine start control apparatus that includes sensors for vehicle speed, accelerator pedal position, battery voltage, and engine coolant temperature, which calculates the demanded power level and discharge capacity level to initiate the engine starting procedure before the demanded power level reaches the discharge capacity level, thereby ensuring timely power generation and delivery to the traction motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine starting procedure is initiated immediately when the actual current level exceeds the allowable discharge capacity, then the battery discharge limit is respected, but an engine response delay of several seconds occurs causing inconsistent power delivery
Solution Approach 1:
The control unit initiates the engine starting procedure in advance when the demanded power level reaches a predetermined relationship with the discharge capacity level, before the actual current level exceeds the allowable discharge capacity. This preliminary action ensures the engine is ready to generate power without delay when needed, while still respecting battery discharge limits.
Solution Approach 2:
The system predicts the engine response delay and compensates for it by initiating the starting procedure earlier, based on the relationship between demanded power level and discharge capacity level. This preliminary anti-action counteracts the expected delay, ensuring timely power delivery.
2Reliability
If the engine starting procedure is delayed to prevent exceeding battery discharge capacity, then battery protection is maintained, but power delivery to the traction motor is delayed causing driver discomfort
Solution Approach 1:
The control unit performs preliminary action by initiating the engine starting procedure when the demanded power level reaches a predetermined relationship with the discharge capacity level, which occurs before the actual current level exceeds the allowable discharge capacity. This ensures the engine is prepared in advance, maintaining both battery protection and responsive power delivery.
Solution Approach 2:
The control unit continuously monitors the relationship between the demanded power level and the discharge capacity level, using this feedback to determine the optimal timing for initiating the engine starting procedure. This feedback mechanism ensures the engine starts at the right moment to maintain both battery protection and power delivery responsiveness.
3Loss of time
If the engine starting procedure is initiated earlier to compensate for response delay, then power delivery timing is improved, but fuel consumption increases due to extended idle operation
Solution Approach 1:
The control unit changes the parameter for initiating engine start from a fixed threshold to a dynamic relationship between the demanded power level and the discharge capacity level. This parameter change allows the engine to start at the optimal moment based on real-time power demands and battery capacity, improving timing without unnecessary early starts that would waste fuel.
Solution Approach 2:
The system uses feedback from the relationship between demanded power level and discharge capacity level to precisely control when the engine should start. This feedback ensures the engine starts early enough to compensate for response delay but not so early as to cause unnecessary fuel consumption from extended idle operation.
Data Source
AI summary
An engine start control apparatus/method for a series hybrid vehicle is provided. The vehicle includes an engine, a motor/generator, a battery unit chargeable with electric power generated by the motor/generator, and a traction motor operable to receive electric power from the battery unit or motor/generator. A demanded power level is determined based on a sensed vehicle speed level and a sensed accelerator pedal position. A discharge capacity level of the battery unit is determined in terms of a power level available from the battery unit. The engine starting procedure is initiated upon the determined demanded power level reaching a predetermined relationship with the determined discharge capacity level so that the motor/generator is enabled to generate electric power before the determined demanded power level reaches the determined discharge capacity level.