Due to the simple control circuit and control performance of DC speed regulation, the cost of using DC speed regulation in small power system is relatively low, so DC speed regulation is still widely used in small power simple large-scale stacked screw sludge dewatering machine. In order to improve the transmission reliability of the large-scale stacked screw sludge dehydrator, the motor spindle should be used to drive the rotor of the large-scale stacked screw sludge dehydrator as far as possible. At the same time, considering the special requirements of the installation of the large-scale stacked screw sludge dehydrator and the damping system of the whole machine, the motor of the large-scale stacked screw sludge dehydrator generally requires special design in the form of the spindle and the shape of the shell to meet the requirements This paper introduces the special requirements for the transmission of large-scale stacked screw sludge dewatering machine. If belt transmission or other variable speed transmission machinery is used, general standard series motors can be selected, but the reliability of transmission is relatively low.
Speed control system
1. DC speed regulation
(1) Main circuit
There are two kinds of DC speed regulation
① The thyristor rectifying circuit can adjust voltage and speed. The non-toxic dewatered sludge can be directly used as fertilizer in farmland. The moisture content of the sediment in the wastewater treatment process is up to 99%. In order to reduce the volume of sludge and make it convenient for transportation and further treatment, some moisture must be removed before the sludge is treated. The methods to remove water from sludge include gravity concentration, vacuum filtration, pressure filtration, stacking and natural air drying.
② DC pulse width modulation is used to adjust voltage and speed. The characteristics of the two kinds of DC speed regulating circuits are compared as follows.
Pulse width modulation speed regulation. The input DC adopts diode bridge rectifier with high power factor and high modulation frequency. Generally, the working frequency is set at about 20 kHz. Due to the high frequency, it can not only reduce the noise, but also reduce the volume of filter inductor. At present, there are many kinds of integrated circuits for PWM waveform generator, and the control circuit is simple. But the power devices are controllable electronic devices, such as GTR, MOSFET and IGBT. The overload capacity of these devices is relatively low, and the requirements for trigger drive circuit (DC) are high. The front and back edge of trigger pulse should be steep. At the same time, there should be a fast over-current protection circuit. At present, a variety of intelligent special drive integrated circuits have come out, which have a variety of automatic protection functions, which create favorable conditions for the wide application of DC pulse width speed regulation system.
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