Hybrid Machine Battery Controller Feedback Correction
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Solution Overview
Problem
In hybrid construction machinery, the management of electrical storage device remaining amounts is challenging due to deviations from the intrinsic droop characteristic, leading to unintended charging or discharging, and improper power management, which can result in insufficient workability and battery degradation.
Innovation Solution
A controller system that calculates and adjusts the target rotational speed and engine power based on the electrical storage remaining amount, charging/discharging requests, and load power, using a droop characteristic to maintain proper power output and prevent battery overcharging or undercharging, ensuring accurate power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is operated with droop characteristic to maintain constant rotational speed, then the rotational speed can be kept constant and fuel injection amount is reduced according to rotational speed increase, but the torque of the engine does not strictly correspond to the droop characteristic due to dispersion in fuel injection state, combustion state, and torque for each cylinder or engine
Solution Approach 1:
The control device calculates the actual charging/discharging amount of the electrical storage device and compares it with the target charging/discharging amount. Based on the difference between actual and target values, the control device corrects the target rotational speed to generate a corrected target rotational speed. This feedback mechanism compensates for torque dispersion and ensures accurate power management despite variations in engine torque output.
2Power
If the target rotational speed is reduced to increase torque for charging the electrical storage device, then the torque increases according to droop characteristic, but the actual charging amount may exceed or fall short of the target charging amount due to torque dispersion
Solution Approach 1:
The control device calculates the actual charging/discharging amount based on the difference between engine torque and motor generator torque, then compares it with the target charging/discharging amount. When the actual amount differs from the target, the control device corrects the target rotational speed and recalculates the required torque. This iterative feedback process ensures that the actual charging amount converges to the target charging amount despite initial torque dispersion.
3Reliability
If the motor generator is regeneratively driven to maintain target rotational speed when engine torque exceeds droop characteristic, then the calculated target charging amount is charged, but this causes improper power management when electrical storage remaining amount is already proper
Solution Approach 1:
The control device continuously monitors the electrical storage remaining amount and calculates the target charging/discharging amount based on this state. The feedback mechanism compares actual charging/discharging amounts with target values and adjusts the corrected target rotational speed accordingly. This ensures that charging/discharging operations are performed only when necessary and at appropriate times, preventing improper power management while maintaining reliable achievement of charging targets.
Data Source
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AI summary
The present invention includes a battery controller that calculates an electrical storage remaining amount of a battery, a charging/discharging request calculation part that calculates a charging/discharging request amount for keeping electric power outputted by the battery within a predetermined range based on the electrical storage remaining amount calculated, a target rotational speed calculation part that calculates a target rotational speed command value of a motor generator, and an inverter that controls the motor generator according to the target rotational speed command value calculated, and it is configured that at least one of the battery controller and the inverter calculates the actual charging/discharging amount of the battery, and that the target rotational speed calculation part calculates a target rotational speed correction value from difference between the charging/discharging request amount and the actual charging/discharging amount and corrects the target rotational speed command value.