Torque Ripple Control in Interior Permanent Magnet Synchronous Motors
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Solution Overview
Problem
Interior permanent magnet (PM) machines in hybrid electric vehicles experience torque ripple due to magnetic force variations, which existing approaches primarily address through machine design rather than control methods, leading to inefficiencies in noise and vibration reduction.
Innovation Solution
A controller system that manipulates the control angle of the motor current in PM synchronous motors by adjusting direct axis (d-axis) and quadrature axis (q-axis) current commands to prioritize torque ripple reduction over winding loss minimization at specific speed and torque conditions, using look-up tables to switch between optimal loss and ripple reduction strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If motor current is optimized for minimal winding loss, then winding loss is minimized, but torque ripple increases
Solution Approach 1:
The patent applies dynamics by making the control angle adjustable based on operating conditions. The controller dynamically switches between a first control angle (optimized for minimal winding loss) and a second control angle (optimized for minimal torque ripple) depending on the detected motor speed and torque conditions. This dynamic adjustment resolves the contradiction by allowing the system to optimize for winding loss during normal operation while switching to torque ripple reduction when specific speed-torque conditions are met.
Solution Approach 2:
The patent changes the control angle parameter based on operating conditions to resolve the contradiction between winding loss and torque ripple. By detecting motor speed and torque conditions, the controller selects different control angle values from a map or lookup table, thereby changing the electrical torque characteristics to prioritize either loss minimization or ripple reduction depending on the current operating point.
2Object-generated harmful factors
If control angle is adjusted to reduce torque ripple, then torque ripple is reduced, but winding loss increases
Solution Approach 1:
The system dynamically adjusts the control angle based on real-time detection of motor speed and torque conditions. When conditions indicate high susceptibility to torque ripple (specific speed ranges and torque levels), the controller switches to a second control angle optimized for ripple reduction, accepting increased winding loss only when necessary. This dynamic approach resolves the contradiction by making the trade-off conditional rather than constant.
Solution Approach 2:
The control angle parameter is changed based on operating conditions to resolve the contradiction. The controller uses a map or lookup table that provides different control angle values corresponding to different speed-torque operating points, allowing the system to optimize for torque ripple reduction when needed while maintaining winding loss optimization during other operating conditions.
3Object-generated harmful factors
If machine design is used to reduce torque ripple, then torque ripple is reduced, but device complexity increases
Solution Approach 1:
The patent replaces mechanical/design-based torque ripple reduction with an electrical control-based solution. Instead of modifying the physical machine structure (rotor geometry, magnet placement, winding configuration), the invention uses a controller that adjusts the control angle to reduce torque ripple. This substitution resolves the contradiction by achieving torque ripple reduction through software/control algorithms rather than complex mechanical design modifications.
Solution Approach 2:
The invention changes electrical control parameters (control angle, current commands) to reduce torque ripple instead of modifying mechanical design parameters. By using a controller that adjusts the control angle based on operating conditions, the system achieves torque ripple reduction through parameter optimization rather than through complex machine design, thereby resolving the contradiction between effectiveness and device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces torque ripple by altering the control angle, addressing noise and vibration concerns without significant impact on fuel economy, though it may increase winding losses at certain operating points.
Implementation Method 1
The motor output torque contains torque ripples caused by the magnetic force variations depending on the rotor position of the motor
Data Source
AI summary
A system for controlling a vehicle, the vehicle including a permanent magnet (PM) synchronous motor, includes a controller. The controller is configured to control the motor with a motor current. In the presence of a predetermined condition, the motor current results in increased winding loss and reduced torque ripple with respect to optimal motor current for minimal winding loss.