Hybrid Vehicle Engine Start Control via Generator Torque Interference Suppression
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Solution Overview
Problem
In hybrid vehicle systems, generator torque and engine torque interference cause delays and unsuccessful engine starts, as it takes time for the engine to reach idling rotational speed.
Innovation Solution
A vehicle control apparatus with a system controller that drives the generator with a rotational-speed command value smaller than idling maintenance rotational speed, initiates fuel injection after a predetermined time, and includes a lower limit torque limiter to suppress regenerative operation during engine start, ensuring smooth and sure engine starting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the generator operates during engine start, then the generator can provide torque to assist engine rotation, but generator torque and engine torque interfere with each other causing delayed or unsuccessful engine start
Solution Approach 1:
The patent extracts and eliminates the harmful regenerative torque from the generator during engine start by setting the regenerative torque command to zero. This separates the useful function (providing motoring torque to assist engine rotation) from the harmful function (generating regenerative torque that interferes with engine start), allowing the generator to assist engine rotation without causing torque interference.
2Speed
If proportional integration control is used for generator torque control, then the control response is improved, but regenerative operation occurs during engine start causing torque interference
Solution Approach 1:
The patent applies preliminary anti-action by preemptively setting the regenerative torque command to zero before regenerative operation can occur during engine start. The lower limit torque limiter is configured to clamp the regenerative torque command at zero, preventing the harmful regenerative torque from developing while maintaining the proportional integration control for rapid response to legitimate torque demands.
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
The solution enables smooth and reliable engine starting by minimizing interference between generator torque and engine torque, ensuring consistent and efficient engine startup.
Implementation Method 1
a generator 2 driven by the engine 1 to output alternating-current power
Implementation Method 2
a converter 3 that converts alternating-current power output from the generator into desired direct-current power
Implementation Method 3
the lower limit torque limiter suppresses a regenerative operation during start of the engine
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
In a vehicle control apparatus, a system controller that overall controls an engine controller and a converter controller is provided. The system controller drives, through the converter controller, a generator with a generator-rotational-speed command value ωc_ref1 smaller than idling maintenance minimum rotational speed ωe_idol_min of an engine, starts, through the engine controller, fuel injection to the engine after elapse of a predetermined time, and, when the rotational speed of the engine reaches a predetermined rotational speed threshold ωe_th that is larger than the generator-rotational-speed command value ωc_ref and smaller than the idling maintenance minimum rotational speed ωe_idol_min, outputs, to a converter, a gate cutoff signal GSTOP for turning off energization to the generator.