Steer-By-Wire Handwheel Actuator Damping Using Back-EMF
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Solution Overview
Problem
Steer-by-wire (SbW) systems lack effective battery-independent active damping, leading to stability issues during power failures and increased energy consumption in normal operation due to the absence of mechanical interfaces between the handwheel and rack subsystems.
Innovation Solution
Implementing a multi-phase inverter circuit with a power circuit, bipolar junction transistors, and a processor to generate damping signals and control current flow, utilizing motor back electromotive force (BEMF) energy for active damping, and employing a bleeder resistor to optimize damping without relying on battery power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mechanical interfaces are used for steering systems, then stability and feedback are maintained, but energy consumption increases and component size increases
Solution Approach 1:
The patent replaces traditional mechanical interfaces with an electronic control system using a multi-phase inverter circuit. The inverter circuit converts electrical energy to control the motor actuator, eliminating the need for mechanical connections between handwheel and rack subsystems. This substitution reduces energy consumption and component size while maintaining stability through electronic feedback control.
Solution Approach 2:
The system uses the motor's own back electromotive force (BEMF) energy to provide active damping without requiring additional battery power. The multi-phase inverter circuit recovers and utilizes the energy naturally generated by the motor during operation, making the damping function self-sufficient and energy-efficient.
2Use of energy by moving object
If mechanical interfaces are removed in SbW systems, then energy consumption reduces, but stability issues occur during power failures
Solution Approach 1:
The patent implements active damping control using feedback from the torque sensor and processor. The system continuously monitors the steering state and adjusts the inverter circuit output to provide appropriate damping forces. This electronic feedback mechanism ensures stability during both normal operation and power failure conditions without requiring continuous battery power.
Solution Approach 2:
The multi-phase inverter circuit employs periodic switching of bipolar junction transistors to generate damping effects. By controlling the switching frequency and duty cycle of the transistors, the system creates periodic electromagnetic forces that provide active damping, maintaining stability even when battery power is unavailable.
3Use of energy by stationary object
If active damping is implemented without battery power, then power consumption reduces, but damping control becomes difficult
Solution Approach 1:
The system utilizes the motor's inherent back electromotive force (BEMF) as the energy source for active damping, eliminating the need for separate power supply circuits. The multi-phase inverter circuit is configured to harvest and utilize the BEMF energy already present in the system, providing damping control without additional power consumption or complex power management requirements.
Solution Approach 2:
The multi-phase inverter circuit serves multiple functions: it controls the motor actuator during normal operation and simultaneously provides active damping during power failures. By designing the inverter circuit with universal functionality, the patent avoids adding separate damping control hardware, thereby reducing overall device complexity while achieving both motor control and active damping objectives.
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
Enables battery-independent active damping, reducing power consumption and component size, while maintaining stability and feedback during power failures and normal operation.
Implementation Method 1
utilizing motor back electromotive force (BEMF) energy for active damping
Implementation Method 2
at least one bipolar junction transistor
Data Source
AI summary
A system for active damping in a steering system includes a multi-phase inverter circuit associated with a motor. The multi-phase inverter circuit includes a power circuit and at least one bipolar junction transistor. The system also includes a processor, and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive a torque signal corresponding to a torque applied to a handwheel; generate a damping signal based on the torque signal; and selectively control current flow to the at least one bipolar junction transistor based on the damping signal.