Extended Current Detection for Three-Phase Motor Emergency Braking
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Solution Overview
Problem
Existing electronic brake systems using three-phase motors face limitations in controlling braking force due to current sensors' limited range, which prevents proper control of motors when currents exceed the measurable range, especially during emergency braking scenarios.
Innovation Solution
An extended current detecting method that detects current values for at least two phases of a three-phase motor, compares them with a threshold value, and uses a look-up table and Kirchhoff current law to determine current values for the remaining phase, allowing for temporary control beyond the sensor's range during emergency braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sensors are used to detect motor current, then current measurement is possible, but the measurement range is limited and cannot detect high currents during emergency braking
Solution Approach 1:
The current detection is divided into two segments: normal range detection using current sensors and extended range detection using voltage measurements and Kirchhoff's current law. This segmentation allows the system to use different measurement approaches depending on the current magnitude, resolving the contradiction between precise measurement and extended range.
Solution Approach 2:
The patent introduces an intermediary calculation method using voltage measurements and Kirchhoff's current law to bridge the gap between the current sensor's limited range and the high currents required during emergency braking. This intermediary approach allows accurate current determination without requiring the sensor to directly measure extreme currents.
2Power
If higher current is used during emergency braking, then braking performance is improved, but the current exceeds the sensor's measurable range
Solution Approach 1:
The system dynamically switches between different current determination methods based on the operating conditions. During normal operation, current sensors provide direct measurement. During emergency braking when high currents are required, the system transitions to using voltage measurements combined with Kirchhoff's current law, allowing the motor to operate at higher power levels while maintaining measurement accuracy through adaptive methodology selection.
3Adaptability or versatility
If current sensors with extended range are used, then high current detection is possible, but system cost and complexity increase
Solution Approach 1:
The patent makes the existing voltage measurement circuit perform a dual function: it continues to provide voltage information for motor control while also serving as a means for current detection during emergency braking through the application of Kirchhoff's current law. This multi-functionality extends the current detection range without requiring additional specialized hardware, thereby avoiding increased system 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 method enables improved braking performance by allowing higher current control during quick response situations, such as emergency braking, while preventing damage to current sensors and achieving economic advantages by extending the control range without hardware changes.
Implementation Method 1
an electronic brake device which generates the braking force by a rotational force of an electric motor
Implementation Method 2
a torque of the motor is accurately recognized by a current sensor
Data Source
AI summary
Disclosed is a method, including: urgently putting a brake on a vehicle; detecting current values for at least two phases among phases of a motor which operates at a current which is out of a current measurable range through the urgently putting of a brake; comparing the current value detected in the detecting with a threshold value; when it is determined that there is one current value which is equal to or higher than the threshold value among the detected current values in the comparing, removing the current value which is equal to or higher than the threshold value and obtaining a current value for the remaining phase of the motor from a predetermined look-up table; and determining the removed current value using a current value which is detected through the comparing and is lower than the threshold value and the current value obtained through the obtaining.