Hybrid Vehicle Power Output Control for Battery Overcharge Prevention
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Solution Overview
Problem
The existing power output apparatuses for motor vehicles may overcharge the battery when there is a difference between actual and target intake air flow to the engine, especially in low temperature ranges where the charge limit is lower, leading to potential overcharging of the accumulator unit.
Innovation Solution
A power output apparatus that includes an internal combustion engine, an electric power-mechanical power input output mechanism, and a control module that corrects specific parameters such as intake air flow to ensure the engine generates power equivalent to the preset demand before charging the accumulator unit, thereby preventing overcharging by maintaining the charge within the specified limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery charge limit is reduced in low temperature ranges to prevent overcharging, then battery safety is improved, but the available charging capacity is reduced
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the charge limit based on battery temperature. When temperature drops below a threshold, the charge limit is reduced to prevent overcharging and ensure battery safety. This temperature-dependent parameter adjustment resolves the contradiction by adapting the charging strategy to environmental conditions.
Solution Approach 2:
The patent implements preliminary action by correcting the specific parameter (intake air flow) before initiating battery charging. The control module ensures the engine output power matches the corrected demand before allowing charging to occur, preventing overcharging from the outset rather than reacting to it afterward.
2Speed
If the intake air flow is not corrected after engine start, then engine response speed is improved, but the engine output power deviates from demand causing overcharging risk
Solution Approach 1:
The control module performs preliminary correction of the specific parameter (intake air flow) immediately after engine start before charging operations begin. This advance correction ensures the engine operates at the correct power level from the outset, preventing both response delays and power deviation that could lead to overcharging.
Solution Approach 2:
The system employs feedback control by continuously monitoring the difference between actual and target intake air flow, then adjusting the specific parameter to minimize this deviation. The control module uses this feedback to maintain accurate power output matching throughout engine operation.
Data Source
AI summary
In a hybrid vehicle of the invention, the control procedure corrects an idling intake air flow Qidl to enable an engine immediately after its start to generate an output power Pe that is substantially equivalent to an engine power demand Pe*. After the correction, the control procedure controls the engine to have an intake air flow Qe with reflection of an intake air flow correction value Qec and controls a motor MG1 to generate electric power by using the output power Pe of the engine and to charge a battery with the generated electric power within an input limit Win of the battery. The control of the invention ensures that the output power Pe of the engine does not exceed the engine power demand Pe* in restriction of the charge level of the battery. This arrangement effectively prevents the state of charge SOC of the battery, which is charged with the electric power generated by the motor MG1, from exceeding the input limit Win.