Relay Coil Discharge Circuit for Back-EMF Control in EV Charging
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Solution Overview
Problem
Existing relay devices in electric vehicles face challenges with accurate on-off control due to back electromotive force generated in the relay coil during turn-off, necessitating improved discharge performance and adaptability to various use environments.
Innovation Solution
A relay device with a switch that operates based on coil voltage, controlled by a first control unit, and includes first and second discharge units to manage back electromotive force, utilizing pulse width modulation signals and diodes to discharge the force through specific discharge units based on control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a relay device uses a simple discharge circuit, then the device complexity is reduced, but the back electromotive force discharge performance deteriorates
Solution Approach 1:
The discharge circuit is segmented into multiple independent discharge units (first discharge unit with first diode, second discharge unit with second diode) that can operate independently or in combination. Each discharge unit handles specific portions of the back electromotive force, allowing the system to achieve high discharge performance without requiring a single complex discharge circuit.
Solution Approach 2:
The relay device employs dynamic control through control signals that can selectively activate different discharge units based on operating conditions. The control unit dynamically switches between discharge paths using third and fourth switching elements, enabling the system to adapt to varying back electromotive force conditions and optimize discharge performance in real-time.
2Device complexity
If a relay device uses fixed discharge path, then the device complexity is reduced, but the adaptability to use environment deteriorates
Solution Approach 1:
The relay device transitions from a fixed discharge path to a dynamic, multi-path discharge system. Control signals can selectively activate different discharge units based on environmental conditions, vehicle operating modes, and back electromotive force characteristics, enabling the system to adapt to various use environments while maintaining manageable device complexity through modular architecture.
Solution Approach 2:
The discharge circuit is designed with multiple discharge units that can serve different functions depending on activation. The first discharge unit handles normal operating conditions, while the second discharge unit handles abnormal or high-voltage conditions. This multi-functional design allows a single discharge circuit system to handle diverse operating environments without requiring separate dedicated circuits for each condition.
3Measurement precision
If the relay coil generates back electromotive force, then the switch control precision is improved, but the electromagnetic interference increases
Solution Approach 1:
The harmful back electromotive force is extracted and directed through dedicated discharge paths separate from the main control circuitry. The first and second discharge units provide separate extraction paths for back electromotive force, isolating the electromagnetic interference from sensitive control circuits while preserving the precise switch control functionality enabled by the relay coil's back electromotive force.
Solution Approach 2:
The back electromotive force, which generates electromagnetic interference, is converted into a useful discharge current that flows through controlled paths with diodes and switching elements. By directing this energy through regulated discharge units, the system transforms the harmful electromagnetic interference into a controlled energy dissipation process that protects the overall system while maintaining switch control precision.
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 provides adaptive relay devices with fast and efficient discharge of back electromotive force, reducing electromagnetic interference noise and enhancing circuit stability according to environmental requirements.
Implementation Method 1
a back electromotive force generating unit configured to generate a back electromotive force when the relay unit is turned off
Implementation Method 2
a first diode having an anode terminal connected to a first end of the coil; and a second diode having a cathode terminal connected to a cathode terminal of the first diode, and an anode terminal connected to a second end of the coil
Data Source
AI summary
A relay device according to an embodiment of the present invention comprises: a relay unit in which a switch operates according to a voltage applied to a coil; a first control unit that controls a voltage applied to the coil by turning on and off a first switching element according to a first control signal; a first discharge unit and a second discharge unit that discharge a back electromotive force generated in the coil when the relay unit is turned off; and a second control unit including a second switching element, and controlling the back electromotive force to be discharged through the first discharge unit or the second discharge unit by turning on and off the switching element according to a second control signal.