Torque Ripple Compensation Generator for Motor Control
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Solution Overview
Problem
Existing motor control systems face challenges in reducing torque ripple due to the need for large memory capacity to generate compensation values for a wide drive range, which increases CPU costs or limits motor operation range when using CPUs with limited memory.
Innovation Solution
A motor control system that includes a torque ripple compensation generator, which calculates a phase difference using q-axis and d-axis current command values, eliminating the need for a look-up table and reducing memory requirements, allowing for efficient torque ripple compensation without increasing CPU costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a table for generating compensation values is prepared to cover a wide drive range of the motor, then torque ripple compensation effectiveness is improved, but memory capacity requirements increase, leading to increased CPU cost
Solution Approach 1:
The patent extracts only the essential parameters (amplitude and phase of torque ripple) from the comprehensive torque ripple compensation table, and implements a calculation-based approach to generate compensation values on-demand using motor operating conditions (current command values and rotation speed) rather than storing pre-computed values for all possible operating conditions.
Solution Approach 2:
The patent changes the approach from static table lookup to dynamic parameter-based calculation, where compensation values are generated by calculating amplitude and phase parameters based on current motor operating conditions (q-axis current command value, d-axis current command value, and rotation speed) rather than retrieving pre-stored values.
2Quantity of substance
If compensation values are generated by a CPU with limited memory capacity, then CPU cost is reduced, but the compensation range of motor operation is narrowed
Solution Approach 1:
The patent implements a dynamic compensation value generation system that adapts to varying motor operating conditions by calculating compensation parameters (amplitude and phase) based on real-time current command values and rotation speed, enabling the system to cover a wide compensation range without requiring large memory capacity.
Solution Approach 2:
The patent creates a universal compensation mechanism that can handle various motor operating conditions (different current values and rotation speeds) through a single calculation-based approach, rather than requiring separate pre-computed tables for each operating condition, thus achieving wide compensation range with limited memory.
3Ease of manufacture
If a look-up table is used for torque ripple compensation, then implementation simplicity is improved, but memory requirements and device complexity increase
Solution Approach 1:
The patent replaces the mechanical/memory-based look-up table approach with a computational approach using mathematical calculations (arctangent function for phase calculation, amplitude calculations based on current command values and rotation speed), substituting memory storage with algorithmic computation to reduce hardware requirements.
Data Source
AI summary
A motor controller includes an inverter that drives a motor, an operation controller that controls the inverter according to a current command value, and a torque ripple compensation generator that adds a compensation value to compensate for a torque ripple in the motor to the current command value. The operation controller uses, as the current command value, a q-axis current command value indicating a q-axis current in a rotational coordinate system of the motor, and also uses, as the current command value, at least temporarily a d-axis current command value indicating a d-axis current in the rotational coordinate system, and the torque ripple compensation generator calculates a phase difference of the compensation value with respect to the q-axis current command value according to an equation using the q-axis current command value and the d-axis current command value as variables.