Electric Motor Controller Current Sensor Error Correction
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Solution Overview
Problem
Existing controller systems for electric motor systems fail to accurately correct current sensor detection signals in real-time, leading to errors that affect motor performance, especially after the motor is started and during normal operation.
Innovation Solution
A controller system that includes an electronic control unit (ECU) which adjusts the inter-terminal voltage of a smoothing capacitor to match a reference value, allowing for real-time correction of current sensor detection signals by minimizing the difference between the detected and actual phase currents, thereby reducing errors in current measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sensor detection signals are corrected only just after motor startup, then initial detection errors are corrected, but detection errors accumulate during normal operation
Solution Approach 1:
The system performs preliminary correction of current sensor detection errors just after motor startup when the motor is not rotating, establishing a baseline correction value before normal operation begins. This preliminary action prevents error accumulation during subsequent operation.
Solution Approach 2:
The system continuously corrects current sensor detection errors during both startup and normal operation phases. By maintaining continuous correction rather than one-time correction, the system prevents detection error accumulation and maintains accurate current measurement throughout the motor's operational life.
2Adaptability or versatility
If DC bus voltage is allowed to vary during operation, then system flexibility is maintained, but current sensor detection accuracy deteriorates
Solution Approach 1:
The system changes the DC bus voltage parameter from a fixed value to a controlled variable that can be adjusted within a predetermined range. By actively controlling DC bus voltage to maintain it within specified limits, the system ensures accurate current sensor detection while maintaining operational flexibility for different motor loads and conditions.
3Measurement precision
If DC bus voltage is held constant at all times, then current sensor detection accuracy is maintained, but system adaptability to varying load conditions deteriorates
Solution Approach 1:
The system transitions from a static DC bus voltage control approach to a dynamic control approach. The DC bus voltage is actively adjusted within a predetermined range in response to varying motor load conditions, while maintaining it within limits that ensure accurate current sensor detection. This dynamic approach allows the system to adapt to different operational requirements.
Solution Approach 2:
The system uses feedback control to monitor DC bus voltage and make adjustments to maintain it within a predetermined range. By continuously monitoring voltage levels and making corrective adjustments, the system maintains accurate current sensor detection while adapting to varying load conditions through controlled voltage variations.
Data Source
AI summary
A controller for an electric motor system is provided. The electric motor system includes a DC power supply, a power converter, a smoothing capacitor, a three-phase AC motor, and a current sensor. The controller includes an electronic control unit. The electronic control unit is configured to control the power converter such that an inter-terminal voltage of the smoothing capacitor matches a first reference value. The first reference value is a value which is determined as the inter-terminal voltage of the smoothing capacitor when a phase current is equal to a second reference value. The electronic control unit is configured to correct a detection value of the current sensor so as to decrease a difference between the detection value and the second reference value when the inter-terminal voltage matches the first reference value and the detection value does not match the second reference value.