Motor Drive Device Torque Ripple Suppression via Delay Compensation
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Solution Overview
Problem
Conventional motor drive devices experience insufficient suppression of torque ripple and abnormal noise, particularly at high motor speeds due to delays in feedback and calculation from the rotation and current measurement components.
Innovation Solution
A motor drive device with a control section that includes a current command value correcting portion and a voltage command value correcting portion to compensate for delays, using correction values calculated based on the motor's rotation angle and angular speed to generate drive signals that reduce torque ripple and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional motor drive devices are used, then the basic motor driving function is achieved, but torque ripple and abnormal noise occur due to harmonic waves in the inductive voltage
Solution Approach 1:
The current command value correcting portion performs preliminary correction on the current command values Ir_d and Ir_q before they are used for PWM generation. By calculating correction values based on the rotation angle θ and applying them in advance to compensate for harmonic components, the system suppresses torque ripple and noise without requiring complex hardware modifications.
Solution Approach 2:
The invention changes the parameter values of current command values Ir_d and Ir_q by adding correction values that are functions of the rotation angle θ. This parameter modification compensates for the harmonic waves in the inductive voltage, thereby suppressing torque ripple and abnormal noise while maintaining the basic motor control structure.
2Speed
If the motor rotates at high speed, then the motor output power increases, but the suppression of torque ripple and noise becomes insufficient due to delays in feedback and calculation
Solution Approach 1:
The invention replaces the conventional feedback-based mechanical control system with a calculation-based correction system. The current command value correcting portion uses mathematical calculations based on rotation angle θ to generate correction values, substituting the slower feedback mechanism with a faster calculation approach that can keep up with high-speed motor operation.
Solution Approach 2:
By calculating and applying correction values to the current command values before PWM generation, the system performs preliminary compensation that does not depend on feedback delays. This preliminary action ensures effective torque ripple and noise suppression even at high rotation speeds where feedback delays would normally degrade performance.
3Object-affected harmful factors
If current command value correction is applied, then torque ripple and noise are suppressed, but additional calculation portions are required
Solution Approach 1:
The current command value correcting portion is merged with the existing control section, sharing the rotation angle θ calculation from the rotation calculating portion. By combining functions and sharing common data (rotation angle), the invention achieves current command correction without proportionally increasing the overall control section complexity.
Solution Approach 2:
The rotation angle θ calculated by the rotation calculating portion serves multiple purposes: it is used for PWM generation and also for calculating correction values in the current command value correcting portion. This multi-functionality allows the system to achieve noise suppression without requiring separate dedicated sensors or measurement systems.
Data Source
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AI summary
This invention provides a motor drive device capable of sufficiently suppressing the occurrence of torque ripple and abnormal noise even if the motor rotates at high speed. A motor drive device (100) comprises an inverter (1), and a control section (2) for controlling the inverter (1). The control section (2) comprises a current command value calculating portion (21) for calculating a current command value, a rotation calculating portion (22) for calculating a rotation angle θ and an angular speed ω of a motor (150), a current command value correcting portion (24) for correcting the current command value based on the rotation angle θ, a voltage command value calculating portion (25) for calculating a voltage command value based on the current command value corrected by the current command value correcting portion (24), a voltage command value correcting portion (26) for correcting the voltage command value calculated by the voltage command value calculating portion (25) based on the current command value calculated by the current command value calculating portion (21) and the rotation angle θ and the angular speed ω, and a drive signal generating portion (27) for generating a PWM signal based on the voltage command value corrected by the voltage command value correcting portion (26).