Making of electromagnetic brake control circuit with long life and low noise Figure 1 is a common electromagnetic brake circuit in electromechanical equipment. Its working principle is that when K1 (or K2, the motor runs in a different direction) is closed, the motor D is powered and the brake coil L is powered to open the brake. In use, it was found that if the circuit is working for a long time, the brake coil is easily burned, and it is also accompanied by a humming low-frequency call during normal operation. Generally, when the brake is working, the brake coil needs a large current brake to open, and when the brake is opened, the small current can maintain its work. However, the brake coil in Figure 1 has been working in the brake-on mode. The current is large and the working temperature increases for a long time, which is easy to cause burnout. If the manufacturing process of the brake coil is poor, the AC current flowing through the brake coil is easy to bring 50Hz electromagnetic oscillation sound. For this reason, I made an electromagnetic brake control circuit that opens with a large current and maintains its operation with a small current (see Figure 2). After using this circuit, it has stable performance and no noise. It has been used for more than three years and has never appeared. Fault. 0V alternating current, rectified by Z1 all the way to generate 220V pulsating DC current at V1 end, flowing through brake coil L through C. Because the current characteristic of C is from large to small, a large current flows through brake coil L at the moment of power-on At the same time, the motor D is energized; the other channel outputs 24V AC after being transformed by the transformer B, 24V pulsating DC after rectification by Z2, flows through the L coil through D, C continues to maintain L with this small current after charging jobs. Since the DC current flows through the brake coil, the direction of the magnetic field lines of the electromagnet is unchanged, so the coupling is good and there is no noise; when K1 (or K2) is disconnected, the motor loses power, and at the same time B loses power, the brake coil L When no current flows, the brake acts and the motor stops. In order to enable the braking system to start and stop repeatedly and quickly for many times, discharge circuits J and R are added. When the circuit is working, 24V DC voltage at the V1 terminal causes J to pull in, the normally closed contact of J is disconnected, and the discharge circuit does not work; When the circuit stops working, J loses power, and the voltage of C is discharged through a set of normally closed contacts of R and J, preparing for the next start of the brake. D is a protection diode, which prevents the charging current of C from flowing through J and puncturing Z2 when the circuit starts. Disclaimer: This article is the original work of Zhang Zhengde designed by Shenzhen Huaqiang Sanyo Technology, if you need to reprint, please contact the author
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Working principle: when the motor is working (K1 or K2 closed), R1 ～ N both ends 22 
Component selection: No special requirements for all components, 600V / 3A bridge stack for Z1, 600V / 1A bridge stack for Z2, 330uF / 400V capacitor for C, 220V / 24V / 20W industrial transformer for B, J for ordinary small relay, R It is a 47K / 2W carbon film resistor, and D is a 1A / 1000V ordinary diode. This circuit can work as long as it is assembled without error and without debugging. 
