On-Vehicle Power Generator Control for Low-Temperature Startability
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Solution Overview
Problem
Conventional on-vehicle power generation control devices face issues with startability during low-temperature startup, as they may start power generation prematurely due to high rotation pulses, leading to sustained power generation torque despite low engine rotation speed, causing engine stalling and delayed startup.
Innovation Solution
A vehicle power generation control device with switching means, voltage control means, detecting means, and startup control means that gradually increase and decrease excitation current to maintain output voltage, detect engine startup states, and control power generation based on phase voltage frequencies, allowing for prompt stoppage of power generation when engine rotation speed decreases, thereby reducing engine load and improving startability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reference rotation speed is set to a high value to avoid erroneous detection during low-temperature startup, then measurement precision is improved, but power generation cannot be continued during idling operation
Solution Approach 1:
The patent applies dynamics by making the reference frequency adaptive rather than fixed. The control device switches between a first reference frequency (higher) for startup detection and a second reference frequency (lower) for normal operation detection. This dynamic adjustment allows the system to maintain measurement precision during startup while enabling power generation continuity during idling, as the lower second reference frequency permits generation to continue at reduced speeds.
2Productivity
If power generation is started when phase voltage exceeds the first reference frequency during low-temperature startup, then power generation starts promptly, but engine startability deteriorates due to sustained power generation torque
Solution Approach 1:
The patent applies feedback by continuously monitoring the phase voltage frequency and comparing it against reference frequencies to control power generation start and stop. During startup, when the frequency exceeds the first reference frequency, power generation starts. When the frequency drops below the first reference frequency, power generation stops. This feedback mechanism prevents sustained power generation torque during engine startup, improving engine startability while maintaining prompt power generation initiation when conditions are suitable.
3Device complexity
If a single reference frequency is used for power generation control, then device complexity is reduced, but the system cannot adapt to different operational states (startup vs. normal operation)
Solution Approach 1:
The patent applies segmentation by dividing the operational states into distinct phases (startup and normal operation) and assigning different reference frequencies to each phase. The control device uses a first reference frequency for startup detection and a second reference frequency for normal operation detection. This segmentation allows the system to adapt to different operational states while maintaining relatively simple control logic, as each state has its own optimized reference frequency.
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 improves engine startability by reducing power generation torque as engine rotation speed decreases, particularly during low-temperature startups, by promptly stopping power generation, thus enhancing engine startability and preventing stalling.
Implementation Method 1
a control device used for controlling power generation based on rotation speed of the on-vehicle power generator has been known. Particularly, the control device of the on-vehicle power generator detects rotation speed based on alternating current voltage appearing in a stator winding
Implementation Method 2
switching means connected to a field winding of the power generator, for switching current flowing through the field winding to be ON and OFF
Data Source
AI summary
A device for controlling an on-vehicle power generator is provided with switching means, detecting means, voltage control means, startup control means and normal state control means. The voltage control means controls the output voltage of the power generator together with the switching means. The detecting means detects state of the power generation including a startup state where the engine is in startup condition and a normal state where normal power generation has been performed. The startup control means controls the voltage control means to start/stop of the power generation based on the frequency of the phase voltage of the power generator in the startup state. The normal state control means controls the voltage control means in the normal state such that the normal state control means controls the voltage control means to continue the power generation or stops the power generation based on the frequency of the phase voltage.