Hybrid Vehicle Control Device Drag Torque Compensation
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Solution Overview
Problem
In hybrid vehicles with direct coupling types, mechanical losses such as drag torque occur from the motor generator and mechanical elements like belts and pulleys, which hinder engine output and apply a load to the engine, even when zero torque control is implemented.
Innovation Solution
A control device and method that calculate and adjust torque current command values and weak field current command values based on RPM and DC voltage to eliminate drag torque from the motor generator and mechanical elements, ensuring no load is applied to the engine during engine driving mode, using current correction values stored for each RPM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If zero torque control is applied to the motor generator, then the drag torque of the motor generator is removed, but the mechanical elements (belt, pulley) still generate rolling resistance that applies load to the engine
Solution Approach 1:
The patent uses the rolling resistance from mechanical elements, which was previously a harmful factor applying load to the engine, and converts it into a beneficial effect by controlling the motor generator to generate compensating torque. This compensating torque offsets the rolling resistance, transforming the harmful mechanical loss into an opportunity for energy recovery or system optimization.
Solution Approach 2:
The patent dynamically adjusts the torque command value for the motor generator based on operating conditions (RPM, load demands, battery state of charge). By changing the torque parameter in real-time, the system can compensate for mechanical element losses while preventing excessive load on the engine during engine-only driving modes.
2Power
If the motor generator is mechanically coupled to the engine for direct driving, then engine output is enhanced, but drag torque and mechanical losses occur that hinder engine performance
Solution Approach 1:
The patent implements a feedback control mechanism where the control device continuously monitors engine operating conditions, motor generator torque, and battery state of charge. Based on this feedback, the system dynamically adjusts the motor generator torque to compensate for mechanical losses while maintaining optimal engine performance, creating a closed-loop control system that balances power enhancement with loss reduction.
Solution Approach 2:
The system dynamically changes operational parameters including motor generator torque, inverter switching frequency, and battery charge/discharge rates based on real-time conditions. This allows the system to optimize the balance between utilizing motor generator power assistance and minimizing its parasitic losses on the engine.
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
This approach effectively reduces drag torque and mechanical losses, preventing load application to the engine, optimizing motor generator operation, and minimizing efficiency reduction, while also preventing overcharge and deterioration of the electricity storage device.
Implementation Method 1
an inverter configured to drive the motor generator
Implementation Method 2
a motor generator, an inverter for driving the motor generator
Implementation Method 3
a belt and a pulley which transfer a driving force of the motor generator to an engine driving shaft
Data Source
AI summary
A control device for a hybrid vehicle includes: a current command value calculator configured to calculate torque and a weak field current command values input to the inverter; and a current command value correction calculator configured to calculate torque and weak field current correction values added to the torque and weak field current command values, wherein when an accumulation of electricity of the electricity storage device is equal to or larger than a reference value, the current command value calculator is configured to calculate the torque and weak field current command values to make a load applied to the engine by the motor generator zero, and the current command value correction calculator is configured to calculate the torque and weak field current correction values to make a load applied to the engine by the motor driving system other than the motor generator zero.