Motor Converter Torque Control Under Speed and DC Voltage Variation
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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 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 generates magnetic flux and direct current voltage values based on torque and rotational speed, allowing for precise calculation of current command values to improve torque accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single map based on torque command value and magnetic flux command value is used to obtain current 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 direct current voltage
Solution Approach 1:
The patent transitions from a two-dimensional map (torque command value and magnetic flux command value) to a three-dimensional map that includes rotational speed as an additional dimension. This allows the current command value to be accurately determined while accounting for changes in rotational speed and direct current voltage, thereby resolving the contradiction between maintaining simple control structure and achieving high torque accuracy.
2Measurement precision
If the current command value is obtained from a single map without considering rotational speed and voltage changes, then the control calculation remains fast, but the difference between torque command value and output torque increases
Solution Approach 1:
The patent pre-calculates and stores three-dimensional maps that incorporate rotational speed and direct current voltage variations. During control operation, the system only needs to perform a table lookup in the pre-prepared three-dimensional map based on current rotational speed and voltage conditions, which maintains fast control response while achieving accurate torque control.
3Measurement precision
If the magnetic flux command value and current command value are generated without considering direct current voltage changes, then the control algorithm remains simple, but the center point of magnetic flux restriction circle changes causing torque inaccuracy
Solution Approach 1:
The patent makes the magnetic flux command value and current command value dynamic by incorporating direct current voltage as a variable parameter. The three-dimensional maps are generated for different direct current voltage levels, allowing the control system to adapt to voltage changes and maintain accurate magnetic flux control without requiring complex real-time calculations.
Data Source
AI summary
An electric power converter control device controls an electric power converter that performs electric power conversion between a direct current electric 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 and a rotation detection value indicating the rotational speed of the motor; a direct current voltage value generator configured to obtain a direct current voltage value indicating an output voltage of the direct current electric power supply based on at least a modulation rate coefficient targeted by the electric power converter and the magnetic flux command value; and a current command value generator configured to obtain a current command value for controlling the motor based on the torque command value, the rotation detection value, and the direct current voltage value.