Multi Lane Motor Radial Force Control
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Solution Overview
Problem
Multi-lane permanent magnet synchronous motors (PMSM) face challenges in generating controlled radial forces without netting to zero, which limits their operational flexibility and fault tolerance, particularly in safety-critical applications like electric power steering systems.
Innovation Solution
The motor apparatus comprises multiple unbalanced lanes with current demand circuits that modify current demand signals to generate radial forces, allowing for controlled radial forces to be applied to the rotor without affecting torque output, achieved by configuring each lane to produce offsetting radial forces and using sensorless control techniques for detection and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-lane PMSM motors are used to improve fault tolerance and operational flexibility, then reliability is improved, but the ability to generate controlled radial forces without netting to zero is limited
Solution Approach 1:
The motor is divided into multiple independent lanes (at least two), where each lane has its own drive circuit and control circuit. This segmentation allows independent control of radial forces from each lane, enabling the system to generate controlled net radial forces while maintaining fault tolerance through redundancy.
Solution Approach 2:
The patent introduces asymmetric control strategies where lanes are not required to produce equal and opposite radial forces. By allowing asymmetric force distribution among lanes, the system can generate controlled net radial forces for applications like haptic feedback while still maintaining operational flexibility and fault tolerance.
2Device complexity
If all lanes are driven in normal use to reduce switch power ratings, then device complexity is reduced, but control of radial forces becomes more challenging
Solution Approach 1:
The patent implements feedback control mechanisms where the control circuit receives feedback signals about motor operation and adjusts current demand signals accordingly. This enables precise control of radial forces even when all lanes are actively driven, allowing the system to maintain low switch power ratings while achieving accurate radial force control for haptic feedback applications.
Solution Approach 2:
The control system dynamically adjusts current parameters in each lane to achieve desired radial forces. By modifying current magnitude, phase, and timing parameters independently for each lane, the system can control net radial forces while distributing torque generation across all lanes, reducing individual switch power requirements.
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 solution enables the motor to operate smoothly across a wide torque range without net radial forces, providing enhanced fault tolerance and the ability to generate haptic or acoustic feedback, while also reducing unwanted noise and vibration.
Implementation Method 1
By applying AC drive currents to the phases, a magnetic field is produced which will rotate around the stator. The flux of the permanent magnets on the rotor interacts with this rotating magnetic field causing the rotor to rotate in synchronism with field.
Implementation Method 2
The flux of the permanent magnets on the rotor interacts with this rotating magnetic field causing the rotor to rotate
Implementation Method 3
By synthesizing the AC currents from a DC supply using a pulse width modulation technique, the speed and torque of the motor can be carefully controlled.
Data Source
AI summary
A motor apparatus comprises a permanent magnet synchronous motor circuit having a plurality of lanes, each lane comprising a plurality of unbalanced phases. A current demand circuit which receives a torque demand signal having a value equal to the torque that is to be generated by the motor apparatus and generates a respective current demand signal for each lane indicative of the current to be applied to each phase of the lane to achieve the demanded torque. A first drive circuit and a second drive circuit each comprise a plurality of switches which selectively connect the phases of a respective one of the plurality of lanes to a supply such that PWM modulated currents flow in each of the phases that correspond to the demanded current. The current demand circuit is adapted to modify one or both of the current demand signals such that one or both lanes additionally generate a set of radial forces that are applied to the rotor of the motor that do not net to zero.