IPMSM Control Using Hexagonal Voltage Limit
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Solution Overview
Problem
The existing driving systems for interior permanent magnet synchronous motors (IPMSM) face challenges in tracking torque commands at high speeds due to limited DC-link voltage and current, leading to decreased voltage utilization and motor performance, with a reliance on pre-measured look-up tables that are not adaptable to parameter changes.
Innovation Solution
An apparatus that includes a current command generator producing MTPA (Maximum Torque Per Ampere) commands, a correction unit to adjust current commands, a feedback mechanism for voltage information, and a control unit to optimize voltage output, reducing dependency on pre-measured tables and maximizing inverter voltage utilization by using a 3-phase voltage command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage control with inscribed circle limitation is used, then inverter voltage utilization is limited, but high-speed torque tracking performance deteriorates
Solution Approach 1:
The patent dynamically adjusts the voltage control strategy based on operating conditions. At high speeds, it transitions from conventional inscribed circle voltage limitation to a hexagonal voltage limit approach, allowing the voltage utilization to adapt to speed variations and maintain torque tracking performance across the entire speed range
Solution Approach 2:
The patent changes the voltage control parameters by modifying the voltage limit shape from a circular constraint to a hexagonal constraint that better utilizes the inverter's voltage capabilities. This parameter change enables more effective voltage utilization at high speeds while maintaining torque command tracking accuracy
2Reliability
If DC-link voltage and current are limited, then inverter protection is ensured, but torque command tracking at high speed becomes difficult
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the voltage difference between the commanded voltage and the actual inverter output voltage. This feedback is used to correct the current command, ensuring that torque tracking accuracy is maintained even when DC-link voltage and current are limited, while still protecting the inverter
3Ease of operation
If look-up tables are used for current command generation, then control simplicity is achieved, but adaptability to parameter changes is reduced
Solution Approach 1:
The patent enables the control system to self-adjust by using feedback from the actual inverter voltage output to correct the current command. This self-service mechanism eliminates the need for pre-prepared look-up tables while maintaining control simplicity and improving adaptability to parameter changes and operating conditions
Data Source
AI summary
Provided is an apparatus for operating interior permanent magnet synchronous motor in a system including a detector measuring a position and a speed of a rotor of an IPMSM, the apparatus including an output unit generating and outputting a current command driving a MTPA (Maximum Torque Per Ampere) based on the command torque, a correction unit correcting the current command outputted by the output unit, a feedback unit transmitting over-modulated voltage information to the correction unit, a control unit controlling the current command to output a voltage, a first limit unit limiting an output of the control unit using a maximum voltage synthesizable by an inverter unit, and the inverter unit applying a 3-phase voltage command for tracking a command torque to the IPMSM using an output of the first limit unit.