When designing a magnetic latching relay, how to balance the magnetic circuit design to ensure stable state retention and reliable switching?

When designing a magnetic latching relay, balanced magnetic circuit design is the key to ensure stable state retention and reliable switching. Magnetic latching relays use the magnetic force of permanent magnets to maintain the normally open or normally closed state of the contacts, and use pulse signals to excite the coil to achieve state switching. Here are some key considerations and methods for balanced magnetic circuit design:
1. Selection and arrangement of magnets
Magnet materials: Select magnet materials with high magnetic energy product and good stability, such as rare earth permanent magnet materials such as neodymium iron boron (NdFeB) to ensure that sufficient magnetic force is generated to maintain the contact state.
Magnet arrangement: Reasonably arrange the position and polarity of the magnets to ensure that the magnetic force of the magnets can stably keep the contacts in the desired position when the relay is not excited. At the same time, the arrangement of the magnets also needs to consider the impact on the coil magnetic field to avoid mutual interference.
2. Design and optimization of coils
Number of coil turns and wire diameter: According to the rated voltage and current requirements of the relay, the number of coil turns and wire diameter should be reasonably designed. Too many turns may lead to increased resistance and heat generation, while too few turns may not generate enough magnetic field to overcome the magnetic force of the magnet.
Coil polarity: The coil of the magnetic latching relay usually has polarity distinction. The polarity requirements of the coil must be clearly defined during design and strictly controlled during production.
3. Magnetic circuit structure optimization
Magnetic circuit symmetry: Try to maintain the symmetry of the magnetic circuit to reduce magnetic field distortion and unbalanced force caused by structural asymmetry. Symmetrical magnetic circuit design helps to achieve stable contact retention and reliable switching.
Air gap control: Reasonably control the size of the air gap between the magnet and the armature. Too large an air gap will weaken the magnetic force and affect the stability of contact retention; too small an air gap may increase friction and wear, affecting the reliability of switching.
4. Design of armature and core
Material selection: Select materials with good magnetic conductivity and mechanical strength as the armature and core to ensure that they can effectively transmit the magnetic field and withstand the mechanical stress during switching.
Structural design: Optimize the structural design of the armature and core to reduce mechanical vibration and noise generated during switching. At the same time, ensure the matching accuracy between the armature and the core to improve the accuracy and reliability of switching.
5. Simulation and testing
Magnetic field simulation: Use magnetic field simulation software to simulate and analyze the magnetic circuit of the magnetic latching relay to predict and optimize the magnetic field distribution, magnetic force and switching performance.
Experimental test: Use actual tests to verify the effectiveness and reliability of the magnetic circuit design. The test content includes key indicators such as the holding force of the contacts, switching time, and switching reliability.
When designing a magnetic latching relay, the balanced magnetic circuit design needs to comprehensively consider multiple factors such as magnets, coils, magnetic circuit structures, armatures and cores. Through reasonable material selection, optimized design and simulation testing, it can be ensured that the magnetic latching relay has stable state retention and reliable switching performance.