Install large clock on the rooftop - Kexin Stepping Motor Constant Current Chopping Drive High Torque Core

Kexin Architectural Tower Clock Product Structure:                                                                           

The clock system is divided into indoor and outdoor sections.Among which, the indoor section is further divided into master clock systems and PC monitoring sections.

The outdoor section includes the sub-dial, which is further divided into components such as the movement, hands, scales, and lighting system.

● Principle Introduction

The master clock has its own clock circuit, generating second signals with an accuracy of0.04 seconds/day, while continuously receiving time signals from the GPS signal station, the CPU corrects its own time signals to ensure accuracy.

The master clock continuously sends time signals to the slave clocks, and the slave clocks accumulate time.At 15 seconds, the output drive signal activates the motor, completing the timing operation.

The subordinate clock transmits its status back to the master clock and accepts its monitoring. At the same time, the subordinate clock's timekeeping is also monitored by feedback switches, ensuring that the entire subordinate clock forms a closed-loop system. Furthermore, the master clock and subordinate clock together constitute a larger closed-loop system, thereby guaranteeing the overall accuracy of the system.

● Master Clock Section:

a）Control System: The master clock serves as the control center of the system, issuing various control commands and signals from the master clock to regulate the entire system's operation.

The master clock features a timing system with precision equivalent to the system's timing accuracy. When the system is powered, the system's timing accuracy is maintained.0.04 seconds/day, the internal timer of the system can maintain operation for over 10 years during power failure.

The master clock controls the running time of the slave clocks. During system installation, it is necessary to adjust the time of the slave clocks on the master clock.The CPU determines whether the subordinate clocks are running normally, speeding up forward, or speeding up backward based on the time of the subordinate and master clocks. If the system loses power at any time, the master clock can remember the time of each subordinate clock. When the system powers back on, the master clock continues to run based on the remembered subordinate clock times. The main control cabinet requires 9 wires to control the running of each subordinate clock, with 6 wires being motor drive lines and 3 being core feedback lines.

b）Cabinet: The master clock is housed in a tower clock-specific outdoor waterproof cabinet, height1200mm in size, equipped with power supply and door lock, the front, back, and side panels are all removable. Surface undergoes washing, phosphatizing, and hot galvanizing treatments before painting, with the exterior surface meeting national standard Grade 2 and the interior surface meeting national standard Grade 4. Spray...The plastic surface is matte, with even coloration. The flatness of the surface does not exceed within a 1 square meter area.1mm thick, free from wrinkles, cracks, burrs, weld marks, and other defects at the surface corners; the gap between the door and frame is less than 1.5mm; all gaps are designed for waterproofing; the door opens smoothly without any binding or resistance.

●Sub-compound bell part:

1、Mechanical actuator part：

a、Core Appearance: The core shaft is electroplated, and the housing is spray-painted; the core is fully enclosed, oil-free, corrosion-resistant, moisture-proof, shockproof, low noise, low wear, and has a long service life.

b、Movement Structure: Our tower clocks are driven by a constant current chopper method

The motor shaft and worm shaft are rigidly connected, making it easy to ensure the concentricity of the two shafts.

2) The primary stage employs a worm gear spoke structure, rapidly reducing the transmission ratio. The design is simpler and more compact, transforming the originally complex core variable speed structure into a very simple miniature reducer, making it easier to ensure quality.

3) Revamp traditional connection methods for a compact and rational design, ensuring core operation reliability.

4) This core is particularly well-suited for constant current chopper circuit design, ideal for driving constant current chopper circuits.

2、Electrical control section:

a、Time Signal: Sub-clockThe CPU (AT89C51) receives the standard time signal from the master clock once per second, then compares it with its own elapsed time to determine its operation (normal operation, catch up, reverse, wait).

b、Timing Monitoring: Add a feedback switch on the movement shaft, introduce another closed-loop control, and continuously feed back the position of the hour hand to the sub-clock.CPU, the sub-clock CPU compares the feedback signal from the feedback switch (actual running position) with the timing time stored internally (theoretical running position) to adjust the position of the clock hand in real-time, ensuring accurate timekeeping.

c、Driver Circuit: Utilizes a constant current chopper drive method, incorporates closed-loop control to ensure constant current, and guarantees smooth motor operation without losing steps, with low power consumption (only 1/3 of the power of constant voltage drive)1/6), Timekeeping accuracy. Principle as follows:

Sub-dialThe CPU sends control signals to the drive circuit at a frequency of 15KHz. It latches the drive signal from the CPU on the rising edge of the signal. When the drive signal is low, it activates the drive to move the stepper motor one step. At this point, the feedback resistor in the circuit constantly monitors the current. When it reaches a certain level, the feedback signal activates the feedback loop, cutting off the drive circuit, and the current drops. When the current falls to a certain level, the feedback loop closes, and the drive loop opens, repeating this cycle to ensure a constant current throughout the drive circuit.

3、Luminaire section

a、Lighting Duration: 24 HoursLighting can be set at any time within 24 hours; factory default is from 5 PM to 6 AM the following morning.

b、Luminescent body: During external illumination, the luminescent body employs a diameter of5 LED's in red, green, and yellow colors, with a typical brightness of 600mcd; wavelengths at 640nm for red and 525nm for green; lifespan exceeding 100,000 hours. For internal lighting, the light source uses Philips cool light tubes, providing soft and even illumination, suitable for continuous lighting for several years.

c、Lighting Power Supply: For24V AC power supply.