Hybrid EV Charging Control Under Engine Torque Instability
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Solution Overview
Problem
Existing charging control devices for hybrid electric vehicles fail to address the issue of insufficient battery charge when actual engine torque is insufficient due to high intake temperature, knocking, misfire, or resonance, leading to reduced engine torque accuracy and insufficient battery charge.
Innovation Solution
A control device that includes an engine torque reduction unit to stabilize the engine operating point within a predetermined stable region, and a charging control unit to adjust the electric motor's rotational speed to achieve a target charge amount, thereby recovering the battery from an insufficient charge state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the negative torque of the electric motor is reduced to increase its rotational speed, then the rotational speed of the electric motor is improved, but the charge amount of the battery becomes insufficient
Solution Approach 1:
The patent changes the operating parameters of the engine by reducing engine torque to move the operating point into a stable region where torque control accuracy is improved. This parameter change enables the system to achieve reliable torque output from the engine, which then drives the electric motor to generate sufficient charging current while maintaining stable operation, resolving the contradiction between motor speed and battery charge amount.
2Measurement precision
If the engine torque is significantly reduced due to torque deviation, then the negative torque of the electric motor is stuck to the negative torque upper limit value, but the rotation is reduced and sufficient torque cannot be obtained from the low-rotation engine
Solution Approach 1:
The patent implements feedback control by continuously monitoring the engine operating point and adjusting the engine torque accordingly. When torque deviation is detected, the system provides feedback to reduce engine torque and move the operating point to a stable region, ensuring both control accuracy and sufficient torque output are maintained through closed-loop control.
Solution Approach 2:
The patent dynamically adjusts the engine torque based on the current operating conditions and stability requirements. By making the engine torque adjustable and responsive to operating point conditions, the system can optimize torque output while maintaining stability, preventing the electric motor torque from being stuck at limit values.
3Speed
If the engine operates in low rotation area with high intake temperature, knocking, misfire, or resonance, then the rotational speed control is easier, but the actual engine torque becomes insufficient for the required engine torque
Solution Approach 1:
The patent takes preliminary action by proactively reducing engine torque before torque deviation becomes severe. By anticipating stability issues in the low-rotation area and preemptively adjusting torque to move the operating point to a stable region, the system prevents torque accuracy degradation while maintaining adequate rotational speed and power output.
Data Source
AI summary
When the remaining charge amount of the battery decreases to a predetermined value or less, the engine torque reduction control unit reduces the torque of the engine such that the operating point of the engine falls within a predetermined engine torque stable region. Then, in a state in which the operating point of the engine is within the engine torque stable region, the torque of the electric motor is controlled by the charging control unit so that the actual charge amount by the electric motor becomes a preset target charge amount. This makes it possible to recover the battery from a state in which the charge amount is insufficient.