Design and production of embedded electronics, software, tracking-, telemetry- and remote-control applications

Control modules for DC-motorer

Novatron AS has long experience in construction of motor control applications for smaller and medium DC motors, both with analog and PWM based speed control. In addition, Novatron AS has delivered central controls for larger stepper- and asynchronous motor-drives. Most motor-drive projects have been targeted against control of medium and larger ship based searchlighs, searchlights from a few hundred Watts and up to the large stepper- and asynchronous-motor driven searchlights with 3x4kW HMI lamps.

Tracking spotlights for the Lillehammer 1994 Winter Olympics

The best known project we have been involved in was however not a ship based system, but controls for 6 large special designed tracking spotlights fitted around the olympics arena in Lillehammer. These searchlights was an important part of the lighting system used on the main arena during the opening and final shows. Here, we delivered complete motor controls for the 5 motors in each searchlight, the horionstal and vertical tracking motors, the focus, the shutter and the colour filter shifter.

The communication system used was DMX512, a RS485 based bus system with up to 512 individual 8 bit setpoints, widely used in stage and arena lighting. Each searchlight typically usese one byte for positioning of each motor/axis and on byte for on/off functions like shutter close/open. Due to the use of 4kW xenon gas discharge lamps with long warm-up time, these lamps was onstantly on and with the light output controlled by an electrically operated shutter.
DMX is still a commonly used format for stage- and arena-lighting.

Based on received position data and angular sensors in the searchlights, the motors were constantly adjusted to track the received setpoint as closely as possible.

New PWM based motor driver module

The last product in our range of motor drives is a driver for full control of all axes and functions of a smaller searchlight, using PWM control of horisontal and vertical motors and fixed speed control for focus. In addition, the board has an output for controlling the lamp relay.

Images showing PWM motor drive for a smaller searchlight with 2 speed controlled outputs for horisontal- and vertical-positioning and fixed speed output for focus and on/off, developed in 2020.

The module operates from a supply of 24VDC, but might also be used on 12V systems with a minor adjsutment of control parameters. The enclosed module has a size of 120x80x20mm and the small ventilation slots provide the necessary cooling in addition to thermal connection on the back. The PWM design in itself has a high efficiency and produces little heat, thus keeping the temperature low.

The small slots in the lower left are status LED windows, indicators telling if ithe module has power and wether it is running normal. It also has status indicators for each motor and digital outputs and provide indication of error situations like motor-blocked/overcurrent , undervoltage or communication error.

The module on the image is shown with a 3D printed enclosure, something which is well suited for prototype, 0-series and smaller production quantities. Novatron has design and production capacity to handle this in smaller quantities and may assist in connecting with external suppliers for large quantity 3D-production.

The module is designed as a direct replacement for existing analog modules using digital control signals from a switch-based control planel. The connector at the bottom is made for 1:1 compatiblity with existsing panels while the connector on top is 1:1 compatible with the existsing motor and power supply interface.

What makes this module different from the existing analog version is mainly 2 things. First, due to the PWM construction, the module will dissipate far less heat during operation as well as loading the powersupply with a lower average load current. Secondly, it can be remotly controlled over a RS485 based bus through the new green 4-pole connector on the right side.

Panel adapter that allow for connecting
existing panels onto the RS485 bus.

The use of the RS485 bus communication option allow for a reduction in the wiring that is needed, from the previous 12 wire cable to a simpler 4 wire cable. If cabel-fitting is to be made over a larger distance, the cable cost and not least the fitting cost can provide a large part of the total investment. By using the serial option, you only need a standard network cable (CAT5+) or any simple signal cable in comparison to the larger 12 wire cable need previously. I there is already 4 spare wires available in an existing cable, the cost reduction may be even larger. Combined used of an existsing cable is an option, especially on shorter runs as the communication is low speed, robust and well protected.

The bus solution wil be especially suitable if there is a cluster of panels, as on the bridge, which are to control a cluster of searchlights mounted at a distance. Then all searchlights and panels may share the same 4 wire cable or even a wireless link, thus greatly reducing the cabling cost.

Of the 4 wires used, 2 is used for the bidirectional RS485 communication, while 2 are used for power supply. Except for that the 2 signal wires should be a twisted pair, there are few other restrictions. In the other end of the cable, there is either a panel adapter as shown on the picture on the right or a wireless receiver module of the type described under ISM-BAND WIRELESS

Please take contact for additional information on the possibilities that a customized motor driver module may provide.