Electric Brake Motor Torque Control via Phase Advance
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Solution Overview
Problem
In electric brake systems, the mechanical offset control for IPM motors leads to reduced accuracy and controllability due to variations in sensor attachment errors, causing torque amplification in one direction while decreasing torque in the opposite direction, which affects brake pressure control.
Innovation Solution
The electric brake device incorporates an electric motor controller that performs electrical advance control by adjusting the current phase of the inverter and inhibiting advance in reverse rotation, reducing the mechanical offset error and enhancing controllability in both rotational directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If mechanical offset control is used to amplify torque in one rotational direction, then torque is improved in that direction, but controllability deteriorates in the reversed rotational direction
Solution Approach 1:
The patent applies dynamics by making the advance amount variable based on rotational direction. The control device dynamically adjusts the advance amount to be larger in the first rotational direction for torque amplification, and smaller or zero in the reversed rotational direction to maintain controllability. This dynamic adjustment resolves the contradiction by adapting the control parameter to the operational context.
2Force
If mechanical offset control is used with fixed sensor attachment, then torque amplification is achieved in one direction, but measurement precision deteriorates due to attachment errors
Solution Approach 1:
The patent replaces the mechanical offset method with an electrical control approach. Instead of physically offsetting the sensor attachment position, the control device electrically adjusts the advance amount by controlling the current phase angle of the inverter. This substitution eliminates the measurement precision issues caused by mechanical attachment errors while achieving the same torque amplification effect.
3Force
If advance control with mechanical offset is implemented, then torque amplification is achieved, but device complexity increases due to precise sensor attachment requirements
Solution Approach 1:
The patent eliminates the need for precise mechanical sensor attachment by substituting the mechanical offset method with electrical control. The control device achieves torque amplification through electrical phase angle adjustment of the inverter output, thereby simplifying the mechanical assembly requirements and reducing device complexity.
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 optimally controls torque in both rotational directions, reducing the decrease in maximum hydraulic pressure and improving the accuracy of advance control, thereby enhancing controllability and maintaining maximum torque application.
Implementation Method 1
a magnetic torque caused by a suction/repulsive force between the coil and the permanent magnet
Implementation Method 2
a reluctance torque caused by a change in magnetic reluctance in a gap between a stator and a rotor
Data Source
AI summary
An electric brake device includes: a motor cylinder device that generates a hydraulic pressure in accordance with a brake operation of a driver with an electric motor; a rotational angle sensor that detects a rotor rotational angle θ of the electric motor; and a motor control section that controls an output torque of the electric motor corresponding to the rotor rotational angle θ and controls the electric motor by advancing a detection value of the rotational angle sensor. The current phase setup section sets a current phase to an advanced side as an electrical advance control. The current phase setup section inhibits the advancing the detection value when the electric motor performs reversed rotation, or sets the current phase to a retarded side.