PWM Relay Coil Control for Automotive Module Heat Reduction
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Solution Overview
Problem
In motor vehicles, the integration of an electromechanical relay in electronic control modules is challenging due to space constraints and increased temperatures, which can lead to energy losses and risks of fire from electronic component failures, especially when the relay generates heat from electric actuation currents.
Innovation Solution
A PWM width modulation voltage switching control circuit is used to supply the relay coil downstream of the relay power contact, with a control circuit that provides a reduced average voltage to the relay coil, ensuring reliable engagement and minimizing energy losses and heating, while isolating the module from the main power source during failure states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If an electromechanical relay is integrated in the electronic control module housing, then the overall device size is reduced and installation is facilitated, but the relay generates heat from electric actuation currents which increases the operating temperature of electronic components
Solution Approach 1:
The patent applies periodic action by using PWM (pulse width modulation) to supply the relay coil with intermittent voltage pulses rather than continuous voltage. The control circuit switches the coil voltage on and off at high frequency, creating periodic magnetic fields that maintain the relay contact in the closed position while significantly reducing average power consumption and heat generation. This allows the relay to be integrated in the electronic control module housing without excessive temperature rise.
2Reliability
If a traditional electromechanical relay is used with continuous voltage supply, then reliable protection is ensured, but energy losses and heating are significant
Solution Approach 1:
The patent uses periodic voltage pulses through PWM control to maintain the relay contact closed. By switching the voltage on and off periodically at appropriate frequencies, the magnetic field is regenerated continuously, maintaining reliable contact closure while the average energy consumption is dramatically reduced compared to continuous voltage supply.
Solution Approach 2:
The patent changes the voltage supply parameters by using variable duty cycle PWM signals. The control circuit can adjust the pulse width and frequency to optimize the balance between maintaining reliable relay operation and minimizing energy consumption. This parameter adjustment allows the system to maintain protection reliability while reducing energy losses in the relay coil.
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 effectively reduces energy losses and heating in the electromechanical relay, allowing for its integration within the electronic control module housing while providing protection against fires from component failures, thus addressing the challenges of space and temperature constraints.
Implementation Method 1
having a magnetic circuit in which a magnetic field is generated by a control coil when the latter is traversed by an electric current
Implementation Method 2
the electromechanical relay is a member which by itself also generates heating resulting from the passage of the electric actuation current in its control coil
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Electronic control device (100) for electric actuator (200) in a motor vehicle, comprising an electronic control module (1) having an output providing the electric actuator (200) with a width-modulated chopped supply voltage, comprising an electromechanical relay protection device (2) whose control coil (21) is powered by a width-modulated voltage-cutting coil control device (25), and in which the electronic control module (1) is supplied between a common ground and a relay output (24) of said electromechanical relay protection device (2).