Motor Drive Device Torque Ripple Suppression via Electric Angle Compensation
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Solution Overview
Problem
Existing motor drive devices fail to sufficiently suppress torque ripple, especially at high rotation speeds, due to deviations in magnetic pole phase detection, leading to increased vibration and noise.
Innovation Solution
A drive device with an electronic control unit that calculates the electric angle and rotation speed, sets an electric angle compensation amount, and corrects the torque to cancel torque ripple, using a combination of feedback and feedforward terms to control the inverter and suppress torque ripple effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnetic pole phase detector is used to detect the magnetic pole phase of the motor, then the control device can calculate the torque ripple suppression signal, but the detected magnetic pole phase deviates from the actual magnetic pole phase when torque changes, especially at high rotation speeds
Solution Approach 1:
The control device calculates the actual magnetic pole phase based on the relationship between torque and magnetic pole phase, and uses this calculated phase as feedback to correct the detected magnetic pole phase. This feedback mechanism compensates for the deviation between detected and actual phases, improving torque ripple suppression effectiveness especially at high rotation speeds.
Solution Approach 2:
The control device changes the magnetic pole phase parameter by calculating a corrected magnetic pole phase that accounts for torque-induced deviations. This parameter adjustment ensures accurate torque ripple suppression across varying operating conditions, particularly when rotation speed and torque fluctuations are significant.
2Speed
If the inverter switches a plurality of switching elements to drive the motor, then the motor can operate at high rotation speeds, but torque ripple increases due to deviation between detected and actual magnetic pole phases
Solution Approach 1:
The control device uses feedback from the calculated actual magnetic pole phase to correct the detected phase, ensuring accurate torque ripple suppression even at high rotation speeds where switching effects cause significant phase deviations.
Solution Approach 2:
The control device performs preliminary calculation of the actual magnetic pole phase based on torque and phase relationships before generating torque commands. This preliminary action compensates for expected phase deviations, enabling effective torque ripple suppression at high rotation speeds.
3Object-generated harmful factors
If the torque ripple suppression signal is calculated using the detected magnetic pole phase, then the control system can suppress torque ripple, but the suppression is insufficient when rotation speed is high due to phase deviation
Solution Approach 1:
The control device incorporates feedback from the calculated actual magnetic pole phase into the torque ripple suppression signal generation. This feedback ensures that the suppression signal accurately compensates for torque ripple even at high rotation speeds, maintaining high torque control precision.
Solution Approach 2:
The control device adjusts the magnetic pole phase parameter by calculating a corrected phase that accounts for torque-induced deviations. This parameter change ensures that torque ripple suppression remains effective across the full rotation speed range, maintaining precision torque control.
Data Source
AI summary
Basic current commands of a d-axis and a q-axis are set based on a torque command of a motor. Subsequently, when the rotation speed of the motor is high, an electric angle compensation amount is set to be larger than that when the rotation speed of the motor is low, and a corrected predicted electric angle is set by adding the electric angle compensation amount to a predicted electric angle predicted from an electric angle based on a rotation position of a rotor of the motor from a rotation position detection sensor. Then, current commands of the d-axis and the q-axis are set by multiplying the basic current commands of the d-axis and the q-axis by a correction coefficient based on the corrected predicted electric angle, and an inverter is controlled using the current commands.