Electric Vehicle Brake Control Device Low Speed Transition
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Solution Overview
Problem
The existing brake control devices for electric vehicles face issues with maintaining a consistent braking force at low speeds, leading to uncomfortable rides due to delayed mechanical brake response and increased wear on brake shoes, and require complex structures with advanced notice signals for electric braking effectiveness.
Innovation Solution
A simplified brake control device that adjusts the electric braking force when the vehicle speed is low, using a required braking force calculator and an adjuster to output a smaller electric braking force as feedback, allowing the mechanical brake to be controlled based on this feedback to match the total braking force with the required force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If precharge control is applied to reduce space between brake shoe and wheel for faster mechanical brake response, then response speed is improved, but brake shoe wear increases and wheel maintainability worsens
Solution Approach 1:
The mechanical brake is activated in advance before electric braking becomes ineffective, rather than waiting for the threshold speed to be reached. This preliminary activation ensures seamless transition and eliminates the response delay without requiring excessive precharge pressure that would cause brake shoe wear
Solution Approach 2:
The control device continuously monitors electric motor speed and uses this feedback to determine the optimal timing for mechanical brake activation. When the electric motor speed reaches the threshold value, the mechanical brake is automatically activated, creating a closed-loop control system that optimizes the transition point
2Use of energy by moving object
If mechanical brake is activated only when electric braking becomes ineffective, then energy efficiency is improved, but braking force consistency deteriorates at low speeds
Solution Approach 1:
The mechanical brake is activated in advance before electric braking completely fails, ensuring a smooth transition and maintaining consistent total braking force throughout the speed range. This prevents the delay that would otherwise occur when switching from electric to mechanical braking
3Stability of the object's composition
If advanced notice signal interface is added between electric power converter and brake controller, then braking force transition is improved, but device complexity increases
Solution Approach 1:
The brake control device integrates the threshold determination and mechanical brake activation logic into a single unified control system. By merging these functions, the patent eliminates the need for separate advanced notice signal interfaces between the electric power converter and brake controller, reducing system complexity while maintaining smooth braking force transition
Solution Approach 2:
The brake control device performs multiple functions: it monitors electric motor speed, determines when electric braking becomes ineffective, activates the mechanical brake, and calculates the required braking force. This multi-functional approach consolidates what would otherwise require separate dedicated components and interfaces
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 ensures a total braking force equal to the required force at low speeds without the need for complex structures or advanced notice signals, improving ride comfort and reducing brake shoe wear.
Implementation Method 1
Electric braking force for braking an electric railway vehicle is obtained by making an electric motor operate as a generator and applying force of reverse rotation of an armature to axle shafts, the rotational force the direction of which is opposite to the rotational direction of the armature occurring in a conversion from kinetic energy of the electric railway vehicle into electrical energy.
Implementation Method 2
The friction coefficient between a brake shoe and a wheel, the friction coefficient depending on a vehicle speed
Data Source
AI summary
A variable load calculator calculates a variable load command VL based on AS pressure and a predetermined table. A vehicle deceleration calculator calculates vehicle deceleration α based on a brake notch command BN and a predetermined table. A required braking force calculator calculates required braking force BL by multiplying a weight indicated by the variable load command VL and the vehicle deceleration α. An electric braking controller calculates an electric braking pattern in accordance with the required braking force BL and then transmits the electric braking pattern to an inverter controller. The electric braking controller calculates an electric braking force produced by operation of the electric motor and then transmits to a subtractor as feedback BT the electric braking force adjusted in accordance with a speed of the electric motor. The subtractor transmits to a mechanical brake as a mechanical braking command a result obtained by subtracting the feedback BT from the required braking force BL.