Buried Magnet Motor Deadbeat Control for Voltage Response
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Solution Overview
Problem
Existing methods for controlling buried permanent magnet synchronous motors in electric vehicles are unable to react quickly enough to sudden variations in line voltage or resistive torque, such as those occurring during pantograph contact changes or loss of adhesion, due to the use of feedback loops which are slow to respond.
Innovation Solution
A 'deadbeat control' method is employed, where a voltage vector is calculated to directly reach a setpoint without using a feedback loop, ensuring the motor reaches the desired state within a short control period, thereby quickly responding to voltage and torque variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a feedback loop control method is used to regulate the motor current, then the control stability is maintained, but the response speed to sudden variations in line voltage or resistive torque is insufficient
Solution Approach 1:
The patent applies deadbeat control which calculates the voltage vector in advance to directly reach the setpoint current at the end of the control period, eliminating the need for feedback loops. This preliminary calculation of the optimal voltage vector enables immediate response to torque variations and voltage changes without waiting for feedback signals, thus improving response speed while maintaining control stability through precise predictive control
2Speed
If the control period T is reduced to improve response speed, then the response to voltage variations is faster, but the calculation complexity increases
Solution Approach 1:
The patent changes the control parameter from continuous feedback adjustment to discrete deadbeat control with a specific period T less than 5τ. This parameter change enables the system to achieve fast response by calculating the exact voltage vector needed to reach the setpoint current at the end of period T, using transformed rotor reference frame equations that simplify the calculation while maintaining precision
3Loss of time
If a feedback loop is used for current regulation, then the control accuracy is maintained, but the reaction time to sudden torque variations is delayed
Solution Approach 1:
The patent replaces the mechanical feedback loop system with a computational deadbeat control system that uses mathematical transformations in the rotor reference frame. By substituting the physical feedback mechanism with predictive calculations based on motor parameters and setpoint current, the system achieves both fast reaction time and high control accuracy without the delays inherent in feedback loops
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for rapid adjustment to changes in line voltage and resistive torque, minimizing their impact on the vehicle, and is implemented without feeling the inertia of the motor or vehicle, providing smooth operation.
Implementation Method 1
applying by an inverter supplying the motor and during a calculation period T, a voltage vector allowing to obtain, at the end of the period T, a mechanical force developed by the machine equal to a pre-determined setpoint of mechanical force
Data Source
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AI summary
The present invention relates to a method for the quick-response control of a synchronous motor having “buried” permanent magnets, this method consisting in applying, by an inverter supplying the motor, and over a calculation period T, a voltage vector for obtaining, after the period T has expired, a mechanical force developed by the machine equal to a predetermined setpoint, and comprising the following steps: calculation of an eigenvector corresponding to the initial state of the motor representative of the stator current vector and of the magnet flux vector in the initial rotating rotor reference frame at the start of the period T; generation, in the predicted rotating rotor reference frame, of a setpoint current for achieving the determined setpoint at the end of the period T; generation of an eigenvector corresponding to the setpoint state of the motor representative of the setpoint current and of the predicted magnet flux vector in the initial rotating rotor reference frame at the end of the period T; calculation of the voltage vector in the fixed stator reference frame to be applied by the inverter to the motor in order to control it; and application of the voltage vector to the motor by the inverter in order to obtain a current equal to the setpoint current after the period T has expired.