Crossing Gate BLDC Control With Soft Start and Soft Stop
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Historical railroad crossing gates suffer from significant wear due to abrupt motor control systems, leading to oscillation and wear on gate components, which is not effectively addressed by prior designs that utilize mechanical cams and electrical contacts.
Innovation Solution
Implementing a state-machine logic within a Field-Programmable Gate Array (FPGA)/central processing unit (CPU) to control a brushless direct current (BLDC) motor, using internal hall sensors for feedback loops to achieve smooth acceleration and deceleration, eliminating the need for mechanical cams and electrical contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical cam and contact arrangement is used to control the motor, then the gate mechanism can be operated, but significant wear occurs on drive train components and electric brakes due to abrupt stopping
Solution Approach 1:
The patent replaces the mechanical cam and contact arrangement with an electronic control system using a microprocessor or FPGA. This electronic system controls the BLDC motor through software-based state-machine logic, eliminating the mechanical components that caused wear and enabling smooth deceleration to prevent component damage.
Solution Approach 2:
The patent changes the control parameters from abrupt mechanical switching to gradual electronic modulation of motor voltage and current. The state-machine logic adjusts motor acceleration and deceleration rates, ensuring the gate arm and brake rotate to a complete stop before the electric brake is energized, thereby preventing excessive wear.
2Device complexity
If mechanical cams and electrical contacts are used for control, then the system structure is simple, but the gate arm experiences whipping action and oscillation
Solution Approach 1:
The patent replaces mechanical cams and electrical contacts with an electronic control system based on a microprocessor or FPGA. This substitution eliminates the abrupt mechanical switching that caused whipping action and oscillation, providing smooth and stable gate arm operation through electronic modulation.
Solution Approach 2:
The patent implements a feedback mechanism using internal hall sensors in the BLDC motor to detect motor position and speed. This feedback is fed into the state-machine logic, which continuously adjusts control signals to maintain stable operation and prevent oscillation, ensuring the gate arm reaches its destination smoothly without whipping.
3Productivity
If abrupt motor control is used, then the control system is simple and responsive, but significant wear occurs on gate mechanism components
Solution Approach 1:
The patent changes the motor control parameters from abrupt on/off switching to gradual acceleration and deceleration profiles. The state-machine logic modulates voltage and current to the BLDC motor, providing both rapid response when needed and smooth stopping to prevent component wear, thereby maintaining both productivity and reliability.
Solution Approach 2:
The patent implements dynamic control of motor parameters based on the gate arm's position and operational state. The state-machine logic adjusts acceleration and deceleration rates in real-time, enabling fast response during normal operation while providing controlled, wear-free stopping when the gate arm approaches its destination or when the brake is engaged.
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 provides a soft start and soft stop motion, reducing wear on drive train components and electric brakes, enhancing the lifespan of the gate mechanism.
Implementation Method 1
an electric brushless direct current (BLDC) motor which has at least one internal sensing device that is used as a closed feedback loop to determine a position of the BLDC motor and accurately control a speed of the BLDC motor
Data Source
AI summary
A crossing gate mechanism comprises an electric brushless direct current (BLDC) motor which has at least one internal sensing device that is used as a closed feedback loop to determine a position of the BLDC motor and accurately control a speed of the BLDC motor, a crossing gate arm operated via the BLDC motor and a digital control system configured to control operation of the BLDC motor, wherein the digital control system is configured to provide a motor control signal that results in a soft start motion and a soft stop motion of the crossing gate arm. The BLDC motor is controlled by a state-machine logic stored within a Field-Programmable Gate Array/a central processing unit such that the state-machine logic finely controls an acceleration and a deceleration of the BLDC motor that provides a relatively smooth operation of the crossing gate arm when it reaches both horizontal and vertical positions.