Electromechanical Brake Controller Current Limiting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electromechanical brake systems in vehicles, such as aircraft, face challenges with peak power demand, leading to increased size and weight of power supplies and associated components, which is undesirable in weight-conscious environments.
Innovation Solution
Implementing a motor current limiter that sets positive and negative current limits based on motor velocity, reducing peak power demand and allowing for a smaller and lighter power supply, along with closed-loop feedback control for precise motor drive signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power supply is sized to meet peak power demands without current limits, then the motor can deliver full power at all speeds, but the size and weight of the power supply and associated components increase
Solution Approach 1:
The patent applies dynamics by making the current limits variable rather than fixed. The positive and negative current limits are dynamically adjusted based on motor velocity through the relationship I_limit = k * ω, where k is a constant and ω is the motor velocity. This dynamic adjustment allows the system to deliver full power when needed while reducing peak power demands during normal operation, thereby enabling a smaller, lighter power supply.
Solution Approach 2:
The patent changes the parameter of current limits from fixed values to velocity-dependent values. By establishing current limits that are a function of motor velocity (positive current limit and negative current limit both being a function of ω), the system optimizes power delivery across different operating conditions. This parameter change resolves the contradiction by allowing full power capability when required while maintaining smaller average power demands.
2Power
If larger conductors are used to handle peak power demands, then power delivery capability is sufficient, but the size and weight of the braking system components increase
Solution Approach 1:
The dynamic current limiting based on motor velocity reduces the peak power demands that the cabling must handle. Since the current limits are adjusted according to operating conditions (I_limit = k * ω), the cabling only needs to be sized for the reduced peak demands rather than maximum theoretical demands, resulting in smaller, lighter cabling while maintaining sufficient power delivery capability.
3Power
If current limits are set as a function of motor velocity, then peak power demand is reduced, but the controller complexity increases
Solution Approach 1:
The controller uses feedback from the motor velocity sensor to dynamically adjust the current limits. The relationship I_limit = k * ω requires continuous monitoring of motor velocity and corresponding adjustment of current limits, implementing a feedback control mechanism that resolves the contradiction between reduced peak power demand and controller complexity.
Solution Approach 2:
The controller complexity is managed by implementing a straightforward parameter relationship (current limit proportional to velocity) rather than complex control algorithms. This simple parameter change approach achieves peak power demand reduction while minimizing the increase in controller complexity.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A system and method for limiting peak power demand of a controller (26) for an electromechanical actuator. A motor current command is limited to at least one of a positive current limit or a negative current limit, the positive and negative current limits being a function of motor velocity. A motor drive signal is output to the motor in accordance with the limited motor current command.