Suppliers of specialized frequency converters for elevators remind you that the speed control of the frequency converter can achieve constant acceleration and deceleration control of the elevator, which can effectively prevent accidents such as over winding and over unwinding of the elevator; The speed regulation of the frequency converter can also achieve soft start of the motor, eliminating the energy consumption caused by rotor series resistance and having a very significant energy-saving effect.
Structure of frequency conversion speed regulation system for elevator
The frequency conversion speed regulation system of the hoist is mainly composed of a frequency converter; Travel control; Operation control; Composed of energy consumption braking and holding brake, the frequency converter mainly achieves variable frequency speed regulation for the lifting and lowering of the hoist; Travel control mainly provides precise travel control for the transmission, parking, and braking of the hoist; The operation control mainly completes the lifting start, lowering start, fault reset, emergency braking and other operation controls of the hoist; Energy consumption braking and holding brake mainly achieve elevator parking control.
Principle of variable frequency speed regulation
In the application of the hoist system, the frequency converter mainly performs variable frequency speed control for constant acceleration, variable frequency speed control for starting, constant deceleration, variable frequency speed control for stopping, and variable frequency speed control for running. Variable frequency speed regulation adjusts the motor speed by changing the frequency of the input power supply, so the speed regulation range is very wide. Generally, frequency converters can reach 0-400Hz, and the frequency regulation accuracy is generally 0.01Hz, which can well meet the requirements of constant acceleration and constant deceleration stepless speed regulation of the hoist. Therefore, after using a frequency converter, the motor can achieve true soft start and smooth speed regulation. Variable frequency drive speed regulation is different from rotor series resistance speed regulation, which reduces the slip rate, improves the power factor of the circuit, and can output constant torque. The output power varies with the speed, so it has a good energy-saving effect. On the other hand, the frequency converter can also easily change the output torque (i.e. adjust the torque compensation curve), acceleration and deceleration time, target frequency, upper and lower limit frequencies, etc. through software. The frequency converter also has powerful compatibility functions, and can combine functions, set parameters (modify), and dynamically adjust speed according to usage requirements. The frequency converter can also be controlled through terminal blocks to achieve multi-stage speed control of the stroke. Figure 2 is a schematic diagram of the constant acceleration and constant deceleration speed regulation process of the frequency converter. The acceleration and deceleration processes can be flexibly adjusted, which is very beneficial for preventing over winding, over unwinding, derailment, etc. of the hoist.
Variable frequency speed regulation not only has stroke control, but also brake control
Travel control - is a schematic diagram of the lifting and lowering process of the elevator. Travel control is divided into two processes, one is the forward lifting stroke and the other is the reverse lowering stroke. Travel control mainly divides the lifting process of the elevator into different travel intervals. According to the actual situation of each travel interval, different frequency conversion speed regulation can be used to control the lifting speed of the elevator. Travel control not only controls the frequency conversion speed regulation of the entire lifting stroke process of the elevator, but also controls the parking and braking process of the elevator. Travel control can effectively prevent accidents such as over winding, over unwinding, derailment, and overturning of the hoist, making it particularly suitable for special inclined shafts with bends and forks.
Travel control is implemented based on the lifting position (travel interval) of the elevator. The travel controller converts the travel position into a switch signal and performs multi-stage frequency conversion control, parking control, and braking control through the control terminal of the frequency converter.
Braking control - The safe use of the hoist requires a good braking and braking control system, which generally combines energy consumption braking and holding braking. Energy consumption braking mainly utilizes the regenerative energy generated by the inertia of the hoist during deceleration and descent stroke for braking. The frequency converter uses energy consumption units to achieve energy consumption braking, which is a form of soft braking that can effectively prevent mechanical impact and rapid sliding. In order to prevent accidents such as derailment, the hoist is locked with a brake. The brake is usually used when parking. When the vehicle reaches the parking space, the travel controller sends a stop signal to the frequency converter, and at the same time, sends a brake control signal to the brake to implement the brake. In the event of derailment or other accidents, the operation control implements emergency brake.