Drive Controller Phase Imbalance Compensation
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Solution Overview
Problem
Conventional drive controllers for three-phase motors face challenges in maintaining balance at low speeds, leading to power loss imbalances and torque ripple, which cause temperature rises and resistance imbalances in the drive circuit.
Innovation Solution
A drive controller that includes an imbalance calculation unit to determine electrical imbalances between phases, a control value calculation unit to set current control values in the rotating coordinate system, and a balance compensation unit to add compensation values to current control values in directions other than the q-axis, ensuring balanced operation and reducing torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional drive control is used at low speeds, then the motor can operate, but power loss imbalance occurs between phases causing temperature rise and torque ripple
Solution Approach 1:
The patent changes the control parameters by introducing phase-specific current corrections based on detected temperature differences. The control device adjusts the drive current for each phase individually, modifying the electrical parameters to compensate for thermal imbalances and prevent torque ripple during low-speed operation.
Solution Approach 2:
The patent implements a feedback mechanism where temperature sensors detect phase temperature differences, and this information is fed back to the control device. The control device continuously adjusts the drive current based on real-time temperature feedback, creating a closed-loop control system that maintains thermal balance.
2Reliability
If conventional drive control is used at low speeds, then the motor can operate, but electrical imbalance causes torque ripple
Solution Approach 1:
The patent modifies the electrical parameters by applying phase-specific current corrections. The control device adjusts the magnitude and phase of the drive current for each individual phase based on detected imbalances, changing the electrical characteristics to eliminate torque ripple while maintaining reliable motor operation.
Solution Approach 2:
The patent introduces asymmetric control where each phase is controlled differently based on its specific conditions. Instead of uniform three-phase control, the system applies individualized current corrections to each phase, creating an asymmetric control strategy that compensates for inherent imbalances and prevents torque ripple.
3Reliability
If phase imbalance occurs, then temperature rise happens in specific parts, but no compensation is applied
Solution Approach 1:
The patent employs temperature feedback from sensors placed in the drive circuit to detect local temperature rises. This feedback information is used by the control device to dynamically adjust the drive current distribution, redirecting current away from overheating components and maintaining reliable drive circuit performance.
Solution Approach 2:
The control device changes operational parameters by adjusting current distribution based on temperature conditions. When local temperature rise is detected, the system modifies the electrical parameters (current magnitude and phase) to reduce stress on heated components, preventing further temperature escalation and maintaining system reliability.
Data Source
AI summary
An aspect of a drive controller controls drive of a three-phase motor, and includes an imbalance calculation unit that calculates an electrical imbalance between phases in the three-phase motor, a control value calculation unit that calculates current control values in respective axial directions of a rotating coordinate system of the three-phase motor according to a given target, and a balance compensation unit that reduces the imbalance by adding a compensation value to a current control value in an axial direction other than a q-axis of the current control values calculated by the control value calculation unit.