IPM Motor Controller Torque Current Restriction
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Solution Overview
Problem
Existing motor controllers fail to effectively restrict power source current when applied to interior permanent magnet (IPM) motors, as they do not consider the reluctance torque generated due to differences in d-axis and q-axis inductance, leading to insufficient performance.
Innovation Solution
The motor controller uses torque current proportional to the output torque, converting the dq-axis current restriction value to a torque current restriction value, which is then used to restrict the torque current instruction value, thereby appropriately limiting the power source current even in IPM motors that generate reluctance torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the related art motor controller uses a current restriction value calculated based on voltage instruction value and current detection value, then the power source current can be stably restricted to the target power source current or less, but the restriction effect is insufficient when applied to IPM motors that generate reluctance torque
Solution Approach 1:
The patent changes the parameter basis for current restriction from voltage instruction value and current detection value to torque current instruction value. By calculating the torque current restriction value based on the torque current instruction value and the relationship between torque current and power source current, the controller achieves effective current restriction for IPM motors while maintaining compatibility with different motor types
Solution Approach 2:
The patent segments the current control into two independent parts: d-axis current instruction value and q-axis current instruction value. By separately restricting each component based on torque requirements, the controller can effectively manage power source current in IPM motors where reluctance torque depends on both d-axis and q-axis currents
Data Source
AI summary
A motor controller for driving an interior permanent magnet (IPM) motor has a current feedback control unit that calculates a q-axis current restriction value based on a dq-axis voltage instruction value and a dq-axis current detection value, so that a power source current flowing in an inverter circuit is controlled to be equal to or lower than a target power source current. Provided that a torque current proportional to an output torque of the motor is defined as a torque current, a torque current converter converts the q-axis current restriction value to a torque current restriction value by using a d-axis current detection value. A torque current instruction value restrictor restricts a torque current instruction value with the torque current restriction value. A dq-axis current converter converts a post-restriction torque current instruction value to a d-axis current instruction value and a q-axis current restriction value.