In recent years, the contactless transformation of elevator control systems has become a hot topic of discussion in the industry. Among them, Safe Torque Off (STO), brake safety control, and electronic star-delta switching They are the three most critical technologies.
Safe Torque Off (STO) This refers to a power supply capable of inducing rotation that is not applied to the motor. STO technology is used in elevators equipped with AC or DC motors powered and controlled by static components. By cutting off the motor’s power supply, STO enables safe motor control. STO employs a dual-channel circuit architecture, achieving a Safety Integrity Level (SIL) of 3 and featuring a hardware fault tolerance of 1. Combined with real-time comparison of the two channel states, this ensures safe and reliable motor control. As an alternative to contactor-based motor control, STO offers advantages such as low operating noise, compact size, and fast response speed.
Brake Safety Control This refers to the use of safety circuits containing electronic components to achieve safe control of the brake. The brake control is integrated with the power supply, and safe braking is realized through secure control of the brake’s power supply. The brake control unit adopts a dual-actuator design architecture, with independent state monitoring for each actuator, ensuring that brake control is both safe and reliable. By replacing contactors with safety circuits for brake control, this approach offers advantages such as fast response and long service life.
Electronic sealing star This refers to a method of limiting the unintended movement speed of the elevator car by short-circuiting the three-phase windings of the motor while the inverter’s power module remains in a safe torque-off state, utilizing the inverter’s existing power modules. Real-time monitoring by the electronic star-connection circuit ensures thorough pre-diagnosis of circuit faults, thereby guaranteeing the effectiveness of the star-connection control. Compared to the conventional hardware-based star-connection method that relies on contactors, this electronic star-connection approach offers advantages such as smaller size, faster response, and greater reliability.
The contactless system solution not only drives technological innovation in elevator products but also fundamentally addresses the challenges encountered in practical applications, making it profoundly significant.
