Dual Motor Electric Power Steering Synchronization Control
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Solution Overview
Problem
Conventional electric power steering systems for large commercial vehicles face challenges in efficiently controlling dual steering assist motors, ensuring safe operation in case of motor failure, and synchronizing motors to improve steering feel and durability of speed reducers.
Innovation Solution
An electric power steering apparatus and control method that includes a first and second motor, a torque angle sensor, and a controller to detect and synchronize the operation of both motors based on torque value, steering angle, and operation states, with an abnormality determiner and motor current controller to manage assist torque and current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If dual steering assist motors are used to provide sufficient steering force for large commercial vehicles, then steering assistance capability is improved, but motor synchronization control complexity increases
Solution Approach 1:
The controller continuously monitors the operation states of both first and second motors through sensors, detecting parameters such as rotational speed, torque, and position. Based on this real-time feedback, the controller dynamically adjusts the current distribution to each motor, ensuring synchronized operation and maintaining optimal steering assistance force without excessive complexity
Solution Approach 2:
The control system integrates the control of both first and second motors into a single unified controller that manages them as a coordinated pair. This merging approach allows the system to treat the dual motor setup as one integrated unit, simplifying the control architecture while still providing sufficient steering assistance force through combined motor output
2Reliability
If dual steering assist motors operate independently, then system reliability is improved through redundancy, but steering precision deteriorates due to lack of synchronization
Solution Approach 1:
Sensors detect the operation states of both motors including position, speed, and torque parameters. The controller uses this feedback information to continuously monitor synchronization status and make real-time adjustments to current distribution, ensuring that both motors operate in coordination while maintaining the redundancy needed for high reliability
Solution Approach 2:
The controller dynamically changes the current parameters supplied to each motor based on their detected operation states. By adjusting current magnitude and phase according to real-time motor performance data, the system maintains precise synchronization between the two motors while preserving the redundancy that enhances overall reliability
3Force
If motor current is increased to compensate for motor failure, then steering assistance capability is maintained, but motor and speed reducer durability deteriorates
Solution Approach 1:
Under normal operating conditions, the controller distributes current equally between both motors, utilizing only partial capacity of each motor (50% each). This partial action approach prevents excessive stress on individual components during normal operation, preserving speed reducer durability while still providing full steering assistance capability through combined motor output
Solution Approach 2:
The system is designed with redundant motor capacity, where each motor is oversized relative to the required steering assistance force. This beforehand cushioning ensures that if one motor fails, the remaining motor can handle the full load without requiring extreme current increases that would damage the speed reducer, thus protecting component durability while maintaining steering capability
Data Source
AI summary
An electric power steering apparatus includes a first motor configured to provide a force for movement of a rack; a second motor configured to provide a force for movement of the rack in synchronized with the first motor; a torque angle sensor configured to detect a torque value and a steering angle according to steering of a steering wheel; at least one sensor configured to detect an operation state of the first motor and an operation state of the second motor; and a controller configured to control the operation of the first motor and the second motor in accordance with the steering of the steering wheel and to control the operation of the first motor and the second motor based on the torque value, the steering angle, the operation state of the first motor and the operation state of the second motor.