Vehicle Brake Device Motor Control Voltage Boosting
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Solution Overview
Problem
Existing brake devices for vehicles using advance angle control struggle to increase torque output, leading to a slower increase in brake force application speed after the brake force is initiated, as the load on the electric motor abruptly increases when the friction member abuts the rotary body.
Innovation Solution
A brake device with a booster circuit and a motor control unit that switches between a first drive process using a boost voltage and a second drive process using advance angle control, based on the temperature of the booster circuit, to manage the voltage supplied to the electric motor, allowing for earlier initiation of brake force application and maintaining increased speed of brake force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If advance angle control is used to increase rotary speed of the electric motor, then the brake force application can be started earlier, but the torque output from the electric motor does not increase easily, causing the increasing speed of brake force to drop after the friction member abuts the rotary body
Solution Approach 1:
The patent applies dynamics by switching between two drive processes (advance angle control and normal motor control) based on the operational state. The control unit dynamically selects the appropriate control mode: advance angle control during the approach phase to maximize speed, and normal motor control during the braking phase to maximize torque, thereby resolving the contradiction between speed and torque output
Solution Approach 2:
The patent changes the control parameters of the electric motor based on the operational phase. By adjusting the excitation current values (qd-axis components) differently for the two drive processes, the system optimizes performance for each phase: negative d-axis component for speed enhancement in advance angle control, and appropriate d-axis component for torque enhancement in normal motor control
2Power
If a booster circuit is used to supply boost voltage to the electric motor, then the torque output and brake force application speed can be improved, but the temperature of the booster circuit increases, requiring temperature-based control switching
Solution Approach 1:
The patent implements feedback control by monitoring the temperature of the booster circuit and using this information to switch between drive processes. The control unit receives temperature information and adjusts the drive process accordingly, selecting normal motor control when temperature exceeds the threshold to prevent overheating while maintaining adequate performance
Solution Approach 2:
The system dynamically adapts its operation based on thermal conditions. By switching between boost voltage mode (for high torque) and normal voltage mode (for thermal management), the system maintains optimal performance while preventing excessive temperature rise in the booster circuit
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
The solution enables the brake force to be applied to the wheel at an earlier stage and suppresses the drop in increasing speed of the brake force after initiation, by utilizing a higher boost voltage during cooler conditions and switching to a lower reference voltage when the booster circuit temperature rises, thus protecting the circuit and maintaining effective torque output.
Implementation Method 1
a booster circuit configured to boost a reference voltage, which is a voltage output from a vehicle-mounted power source
Implementation Method 2
a brake actuator including an electric motor and configured to apply brake force to a wheel in accordance with a rotary amount of the electric motor
Implementation Method 3
a friction member (for example, brake pad) to be pressed against the rotary body by force transferred from the brake actuator
Data Source
AI summary
This brake device is provided with: a brake actuator which applies to a wheel a brake torque depending on the rotation of an electric motor; a booster circuit which boosts a reference voltage outputted from a battery; and a motor control unit which controls the electric motor. Depending on the state of the booster circuit, the motor control unit switches between a first drive process for driving the electric motor by supplying thereto a boost voltage, which is a voltage that has been boosted by the booster circuit, and a second drive process for driving the electric motor by supplying a reference voltage to the electric motor and by performing spark advance control.