EPB Motor Current Control for Voltage-Dependent Braking Force
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Solution Overview
Problem
The motor-on-caliper type electronic parking brake (EPB) system faces issues with inconsistent parking braking force due to voltage fluctuations, leading to insufficient or excessive braking force, which affects product competitiveness by requiring larger margins to compensate for variations.
Innovation Solution
Incorporating a motor driver, current sensor, and electronic control unit (ECU) that adjusts the target current based on sensed voltage to maintain consistent parking braking force, with the ECU changing the target current to lower or higher values depending on voltage conditions to ensure adequate braking force without excessive margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a larger margin for parking brake force is set to compensate for voltage fluctuations, then the reliability of parking braking force is improved, but the weight and price of the product increase
Solution Approach 1:
The system implements feedback control by sensing the actual voltage supplied to the electric motor through a voltage sensor, comparing it with the target voltage, and adjusting the target current accordingly. When the sensed voltage is higher than the target voltage, the target current is reduced; when the sensed voltage is lower, the target current is increased. This closed-loop feedback mechanism ensures consistent parking braking force without requiring excessive design margins.
Solution Approach 2:
The system dynamically changes the target current parameter based on the sensed voltage conditions. The ECU adjusts the target current to a first target current (lower than reference) when voltage is high, and to a second target current (higher than reference) when voltage is low. This parameter adaptation allows the system to maintain reliable braking force consistency while using the minimum necessary component margins, thereby reducing weight.
2Reliability
If a larger margin for parking brake force is set to compensate for voltage fluctuations, then the reliability of parking braking force is improved, but the price of the product increases
Solution Approach 1:
The feedback control system monitors voltage in real-time and adjusts target current accordingly, ensuring consistent parking braking force. This eliminates the need for expensive over-engineering with large safety margins, as the system actively compensates for voltage variations through control rather than through oversized components.
Solution Approach 2:
By dynamically adjusting the target current parameter based on sensed voltage, the system achieves reliable braking force consistency without requiring expensive components with excessive margins. The ECU's ability to change target current to first or second target currents based on voltage conditions allows cost-effective maintenance of braking performance.
3Force
If the target current is increased to ensure sufficient parking braking force, then the parking braking force is improved, but the energy consumption increases
Solution Approach 1:
The system optimizes energy consumption by dynamically adjusting the target current parameter based on actual voltage conditions rather than using a fixed high current. When voltage is high, the target current is reduced to the first target current; when voltage is low, it is increased to the second target current. This ensures sufficient braking force is achieved with minimum necessary energy input.
Solution Approach 2:
The feedback mechanism prevents energy waste by adjusting target current according to actual voltage supply. The system only increases current when necessary (low voltage conditions) and reduces current when voltage is sufficient, thereby achieving the required braking force with optimal energy consumption rather than continuously applying maximum current.
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 allows for constant maintenance of parking braking force, reducing product weight and price by eliminating the need for large margins, thereby enhancing product competitiveness and reliability.
Implementation Method 1
a voltage sensor configured to sense a voltage supplied to the electric motor
Implementation Method 2
a current sensor configured to sense a current flowing in the electric motor
Implementation Method 3
an EPB actuator having an electric motor configured to generate a braking force
Data Source
AI summary
Disclosed is an electronic parking brake (EPB) system. The EPB system has an EPB actuator operated by an electric motor, and the EPB system includes a motor driver configured to drive the electric motor of the EPB actuator; a current sensor configured to sense a current flowing in the electric motor; a voltage sensor configured to sense a voltage supplied to the electric motor; and an electronic control unit (ECU) configured to change a target current to correspond to a parking apply mode that is executed on the basis of a voltage supplied to the electric motor, which is sensed through the voltage sensor when the parking apply mode is executed, and control an operation of the electric motor according to the changed target current.