Motor Control Unit Parameter Estimation via Dead Time Compensation
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Solution Overview
Problem
Existing motor driving apparatuses face challenges in accurately estimating parameters such as phase resistance, counter electromotive force constant, d-axis inductance, and q-axis inductance, which are crucial for efficient motor control, due to nonlinearity and variable conditions.
Innovation Solution
A motor driving apparatus and method that estimates these parameters by supplying d-axis and q-axis test currents, using a step-like composite square wave driving current, and compensating for dead time based on the polarity of the driving current, allowing for precise parameter estimation across varying rotor speeds and torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed constant parameter is used for motor control, then the control system is simple, but the parameter estimation accuracy deteriorates under variable conditions
Solution Approach 1:
The patent implements dynamic parameter estimation by continuously monitoring motor operating conditions (current, voltage, temperature) and updating parameters such as phase resistance, counter electromotive force constant, and inductance values in real-time, allowing the control system to adapt to variable conditions while maintaining reasonable complexity
Solution Approach 2:
The patent changes physical parameters by measuring actual motor characteristics under different operating conditions and adjusting control parameters accordingly, including compensating for temperature effects on resistance and accounting for saturation effects on inductance, thereby improving estimation accuracy without requiring an overly complex system
2Measurement precision
If test currents are supplied for parameter estimation, then the parameter accuracy improves, but the control time increases
Solution Approach 1:
The patent performs preliminary parameter estimation during motor startup or idle periods before full operation begins, so that parameter values are ready when needed, reducing the time penalty during actual control operations
Solution Approach 2:
The patent implements periodic parameter estimation at scheduled intervals during motor operation rather than continuously, updating parameters at appropriate moments (e.g., during steady-state operation or between load changes) to balance accuracy with minimal disruption to control timing
3Measurement precision
If dead time compensation is implemented, then the voltage control accuracy improves, but the control complexity increases
Solution Approach 1:
The patent implements dead time compensation by measuring the actual voltage applied to the motor (accounting for inverter dead time effects) and using this feedback information to adjust the voltage commands, thereby improving control accuracy while managing complexity through systematic feedback mechanisms
Data Source
AI summary
Disclosed herein are a motor driving apparatus and a controlling method thereof. The motor driving apparatus includes a motor having a rotor including a permanent magnet, and a stator, an inverter to supply a driving power to the motor, and a control unit to estimate a parameter using a startup estimation when a rotation speed of the rotor is less than a preset startup speed, to estimate the parameter using a driving estimation with compensating for a dead time when the rotation speed of the rotor is equal to or greater than the preset startup speed and a torque of the rotor is equal to or less than a preset driving torque, and to estimate the parameter using the driving estimation without the dead time compensation when the rotation speed of the rotor is equal to or greater than the preset startup speed and the torque of the rotor exceeds the preset driving torque.