Motor Voltage Phase Control for Overmodulation Speed Changes
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Solution Overview
Problem
Existing electric motor control methods in overmodulation states fail to adequately address response delays, leading to potential overcurrent issues when the rotation speed of the electric motor changes suddenly.
Innovation Solution
The proposed method involves voltage phase control based on a voltage norm command value and a voltage phase command value, where the required time for calculating the final voltage command is considered, and the detected rotation speed parameter is adjusted accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If voltage phase control is performed in overmodulation state without considering response delay, then the control simplicity is maintained, but overcurrent occurs when rotation speed changes suddenly
Solution Approach 1:
The patent applies preliminary action by calculating the required time for voltage command calculation in advance and using this information to correct the rotation speed parameter before it is used in voltage phase control. The controller determines the required time based on the command value calculation model, then corrects the rotation speed parameter by this required time to compensate for the response delay. This preliminary correction ensures that the voltage phase control uses an anticipated rotation speed value that accounts for the delay, preventing overcurrent while maintaining the simplicity of voltage phase control without adding complex control structures.
2Reliability
If excessive compensation is performed on the voltage applied to the electric motor to reliably prevent overcurrent, then overcurrent prevention is improved, but the voltage applied to the electric motor becomes insufficient in normal situations
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the rotation speed parameter based on the required time for voltage command calculation. Instead of applying excessive compensation to the voltage directly, the controller changes the rotation speed parameter used in the voltage phase control calculation. The required time is determined based on the command value calculation model, and this required time is used to correct the rotation speed parameter. This parameter change approach provides precise compensation that adapts to different operating conditions, preventing overcurrent while ensuring adequate voltage is applied during normal operation.
3Speed
If voltage phase control is performed without correcting rotation speed parameter for response delay, then the response time is maintained, but controllability is reduced and overcurrent occurs
Solution Approach 1:
The patent applies preliminary action by performing the rotation speed parameter correction based on the required time before the voltage phase control is executed. The controller determines the required time for voltage command calculation using the command value calculation model, then uses this required time to correct the rotation speed parameter in advance. This preliminary correction of the rotation speed parameter compensates for the response delay inherent in the control system, improving controllability during sudden rotation speed changes while maintaining the fast response characteristics of voltage phase control.
Data Source
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AI summary
An electric motor control method for controlling an electric motor by voltage phase control performed based on a voltage norm command value representing a magnitude of a volage to be supplied to the electric motor and a voltage phase command value representing a phase of the voltage. The method including: acquiring a required time required for calculating a final command value of a voltage applied to the electric motor by the voltage phase control according to a command value calculation model for calculation by using a rotation speed parameter related to a rotation speed of the electric motor; detecting the rotation speed parameter; changing the detected rotation speed parameter based on the required time; and calculating the final command value by using the changed rotation speed parameter according to the command value calculation model.