Motor Converter Current Adjustment for Accurate Torque Control
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Solution Overview
Problem
Existing motor control methods for electric vehicles face challenges in ensuring accurate output torque due to changes in motor rotational speed and direct current electric power supply voltage, leading to discrepancies between torque command values and actual output torque.
Innovation Solution
An electric power converter control device that adjusts current command values based on torque command, motor rotational speed, and direct current voltage, using a magnetic flux command value generation unit, current command value generation unit, and current command value adjustment unit to improve torque accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single map is used to obtain current command values based on torque command value and magnetic flux command value, then the control structure remains simple, but the accuracy of output torque with respect to torque command value deteriorates due to changes in rotational speed and output voltage
Solution Approach 1:
The patent divides the control system into multiple functional units: a magnetic flux command value generation unit that creates initial magnetic flux commands, and a current command value adjustment unit that refines current commands based on detected rotational speed and voltage. This segmentation allows the system to maintain basic control simplicity while adding targeted adjustments to improve torque accuracy under varying operating conditions.
Solution Approach 2:
The patent implements dynamic adjustment of current command values by introducing correction terms that vary with rotational speed and output voltage. The adjustment unit dynamically modifies the current commands based on detected operating conditions, allowing the MTPA line and magnetic flux restriction circle to adapt to changing conditions rather than relying on a fixed single map.
2Reliability
If current command values are adjusted based on rotational speed and output voltage, then torque control accuracy improves, but the control system complexity increases
Solution Approach 1:
The patent incorporates feedback mechanisms by using detected rotational speed and output voltage values to adjust current command values. The adjustment unit continuously monitors operating conditions and applies corrections to maintain accurate torque control, creating a closed-loop system that improves reliability while managing complexity through targeted feedback rather than comprehensive system redesign.
Data Source
AI summary
An electric power converter control device, which controls an electric power converter that performs electric power conversion between a direct current power supply and a motor, the electric power converter control device including: a magnetic flux command value generator configured to obtain a magnetic flux command value based on a torque command value; a current command value generator configured to obtain a current command value for controlling the motor, based on the torque command value and the magnetic flux command value; and a current command value adjuster configured to adjust the current command value based on the torque command value, a rotation detection value indicating a rotational speed of the motor, and a direct current voltage value indicating an output voltage of the direct current power supply.