Motor Power Estimation in Fuel Cell Air Compressors
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Solution Overview
Problem
In fuel cell vehicles, accurately estimating the power consumption of air compressors is challenging due to varying motor power consumption based on driving states like acceleration, deceleration, and constant speed, leading to estimation errors that can damage fuel cells or result in insufficient air supply.
Innovation Solution
A method that determines an error voltage for terminal voltages applied to each phase of a motor by an inverter, generates a compensation terminal voltage, and calculates power consumption using detected currents, allowing for precise estimation of motor power consumption without individual sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a map mapping power consumption onto flow rate or rotational speed through test is used, then estimation can be performed without individual sensors, but power consumption estimation precision deteriorates due to variations in driving states such as acceleration, deceleration, and constant speed
Solution Approach 1:
The patent changes the parameters used for estimation from simple rotational speed or flow rate to a comprehensive set including terminal voltage, current, rotational speed, and acceleration. By incorporating multiple parameters that capture different aspects of motor operation, the system achieves precise power consumption estimation across varying driving states without requiring individual sensors on each auxiliary system.
2Productivity
If terminal voltage prediction value is derived in preset manner during motor operation, then power consumption can be calculated, but estimation error occurs due to switching element operation in inverter
Solution Approach 1:
The patent employs feedback by detecting the actual terminal voltage applied to the motor and comparing it with the predicted terminal voltage. The difference (error voltage) is then used to correct future predictions, creating a closed-loop system that continuously improves estimation accuracy. This feedback mechanism compensates for errors introduced by inverter switching element operations.
Solution Approach 2:
The system performs preliminary detection of terminal voltage errors during motor operation and uses this information to generate compensation values before they significantly affect power consumption calculations. By anticipating and correcting errors in advance, the system maintains high precision in power estimation.
3Device complexity
If power consumption estimation is performed based on motor rotational speed only, then simple estimation is possible, but accuracy deteriorates due to different power consumption at same speed during acceleration, deceleration, and constant speed states
Solution Approach 1:
The patent transitions from a static estimation approach (using only rotational speed) to a dynamic approach that incorporates acceleration information and terminal voltage variations. By considering the rate of change of speed and the actual electrical parameters, the system accurately captures power consumption differences during acceleration, deceleration, and constant speed operations, even when rotational speed is identical.
Data Source
AI summary
A method for estimating power consumption of a motor includes steps of: determining an error voltage for a terminal voltage of each of multiple phases of the motor, the terminal voltage being supplied from an inverter to the motor; generating a compensation terminal voltage for each of the multiple phases of the motor by applying the error voltage to a prediction value of the terminal voltage that is derived in a preset manner during operation of the motor; and calculating power consumption of the motor by using the compensation terminal voltage and a current value obtained by detecting a current that flows in each of the multiple phases of the motor.