Relay Controller Pull-In Holding Current Commutation
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Solution Overview
Problem
Existing relay systems face high current consumption, high inductance, and slow commutation issues due to the excitation winding, leading to increased power loss and reduced service life, particularly in automotive applications where energy efficiency and low CO2 emissions are crucial.
Innovation Solution
A relay controller that controls the excitation current by managing pull-in and holding currents, utilizing a commutation device to efficiently manage the current flow through the excitation winding, reducing power consumption and extending the relay's service life by optimizing the temporal sequence of operations and integrating a temperature sensor for power reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-side switch is used to connect the excitation winding to the battery, then the relay can be controlled, but high current consumption and high inductance occur
Solution Approach 1:
The patent applies dynamics by transitioning from a static high-side switch configuration to a dynamic control system that alternates between high-side and low-side switching modes. The controller dynamically switches the excitation winding between positive voltage (for pull-in) and negative voltage (for commutation), optimizing current consumption at different operational phases while maintaining reliable relay control.
Solution Approach 2:
The patent implements periodic action through pulsed current delivery to the excitation winding. Instead of continuous current flow, the system delivers periodic pulses during pull-in phase followed by periodic reversal during commutation phase. This periodic switching reduces average current consumption while maintaining effective relay operation and faster commutation.
2Reliability
If many windings with thin wire are used in the excitation winding, then the impedance is high, but the inductance becomes high making commutation difficult
Solution Approach 1:
The patent applies inversion by reversing the voltage polarity across the excitation winding during commutation. Instead of simply disconnecting the voltage source, the system actively applies negative voltage through the low-side switch, creating a reverse current that rapidly demagnetizes the winding. This inverted voltage approach overcomes the high inductance effect and enables fast commutation.
Solution Approach 2:
The patent changes the voltage parameter from positive to negative during commutation phase. The controller dynamically adjusts the voltage polarity across the excitation winding, switching from battery voltage (positive) during pull-in to negative voltage during commutation. This parameter change enables rapid current reversal and reduces commutation time despite high inductance.
3Reliability
If a diode is used for commutation, then the commutation current can flow through the diode, but the commutation voltage is low causing slow commutation
Solution Approach 1:
The patent replaces the passive diode-based commutation system with an active electronic switching system. Instead of relying on diode forward voltage drop, the system uses a controllable low-side switch to actively apply negative voltage. This substitution transforms the commutation mechanism from passive current flow to active voltage-driven current reversal, significantly increasing commutation speed.
4Speed
If a zener diode is used for commutation, then the commutation current can flow through breakdown, but power loss is very high
Solution Approach 1:
The patent replaces the expensive high-power zener diode with a low-cost, low-power MOSFET switch. The MOSFET can handle the commutation current with minimal power loss due to its low on-resistance, eliminating the need for expensive high-voltage zener diodes while achieving fast commutation through active negative voltage application.
5Speed
If a resistor is used for commutation, then the commutation voltage is high enabling rapid commutation, but a high voltage pulse arises after turn-off requiring expensive high-voltage switches
Solution Approach 1:
The patent makes the low-side MOSFET switch multi-functional by using it for both normal low-side switching and commutation operations. The same switch that controls the relay output also serves as the commutation switch, applying negative voltage to the excitation winding. This eliminates the need for separate high-voltage switches and simplifies the overall device architecture while maintaining fast commutation.
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 effectively reduces current consumption, enhances the efficiency of relay operations, and prolongs the service life of the relay by managing current flow and temperature, addressing the inefficiencies and reliability issues in existing systems.
Implementation Method 1
an excitation winding (310) of a relay (300)
Implementation Method 2
A resistor has the disadvantage that a high voltage pulse arises shortly after turn-off
Data Source
AI summary
The invention relates to a relay controller for controlling an excitation current of a relay, wherein the relay controller is designed, upon the energization of the relay by means of a switch, to control the excitation current through the excitation winding of the relay in such a way that through the excitation winding there flows firstly a pull-in current and, after a pull-in time has elapsed, through the excitation winding there flows a holding current that is lower than the pull-in current, and wherein the relay controller is designed, upon the switching-off of the relay by means of the switch, to feed a commutation current that flows through the excitation winding to the commutation device through the first terminal and through the second terminal of the relay controller.