By using advanced electric motors, a variety of motor and pump parameters can be customized to individual customer needs.
It is becoming increasingly more valuable to be able to monitor all electronic components on board medical devices. By taking advantage of the full capabilities and digital customization of brushless direct current (BLDC) motor controllers, pumps can be optimized to monitor and control pump performance, improve efficiency and accuracy, and extend the operating life of many components on board the devices. Also, with the amount of data available and ability to monitor, predictive maintenance, just-in-time replacement and even self-diagnosis becomes more realistic.
More and more customers are demanding a perfect fit for their device. Off-the-shelf items no longer make the cut and even mechanically modified products can fall short of expectations. Many pump companies offer a wide range of products, and KNF has also outfitted our product line with advanced BLDC motors to fill the gaps between products. Complementing this strategy is the ability to tie pumps into sensors and accessories to precisely control accuracy of flow rates and pressure requirements. In many cases, systems can be simplified, and size reduced with a close loop smart pump system while improving precision and accuracy with real-time adjustability and control.
For some BLDC motor options, KNF has also developed and defined its own control protocol which is transmitted via the serial digital interface Universal Asynchronous Receiver Transmitter (UART). In addition to this serial digital interface, the user can control the motor speed by a pulse-width modulation (PWM) signal or an analog control voltage.
BLDC Motor Status Always Accessible
By sending a signal to the motor, customers can start and stop the pump or adjust its speed without changing or disconnecting the operating voltage of the motor. Depending on the type of BLDC motor, communication with the motor enables receiving information such as motor speed, motor status, temperature, electrical current and error messages. This way, the customer can always monitor the operational status of the pump and use the generated data for further processing.
Digital Pump Customization Opens Up Possibilities
Many parameters can be defined. The customizing options vary depending on the motor type used.
- Motor Speed Range
The motor speed range defines the permissible minimum and maximum motor speed. It is also possible to set the motor speed to a fixed value. The motor speed is regulated by the internal controller.
- Motor Speed Ramp
The motor speed ramp defines the maximum allowed acceleration of the motor. This can be used to avoid high electric loads caused by rapid changes in the motor speed.
- Threshold Values
Threshold values can be defined for maximum temperature, maximum electrical current and maximum locked-rotor period. This period defines the time allowed for the shaft to stand still when it should rotate. When one or more thresholds are exceeded, the motor stops and issues an error. Temperature thresholds take on increased importance as devices get smaller and therefore there is less “breathing room” to dissipate heat. Limiting maximum current draw or programming a slow start feature to reduce initial spikes of in-rush current, for example, can be used to reduce power needs. This is also a nice feature when filters could clog and cause pressure build-up within a system. In this case, a pump would normally experience a spike in power draw.
- Starting Behavior
The starting behavior defines whether the motor starts running directly when an operating voltage is applied or only after a command has been received.
- Motor Speed Output
The motor speed output defines how the current motor speed is indicated at the “Motor Speed Output” (not UART). A PWM signal (default) or 6 or 60 pulses per revolution may be selected.
- Control Characteristic
When using the PWM signal or the analog control signal for setting the motor speed, a control characteristic must be defined via parameterization, the setting of unique motor parameters during initial motor programming. The control characteristic describes the relation between the PWM signal or the analog control signal and the motor speed. Therefore, a lower and upper limit for the PWM signal or the analog control signal must be defined. Below this lower limit for the input signal there are two possibilities: either the motor stops, or the motor turns at the defined minimum motor speed.
Another key area of application for pump digital customization is in product testing. For medical devices or any FDA approved system, batch to batch consistency and repeatability is vital. With any pump there is going to be some fluctuation from piece to piece or batch to batch due to the compiling dimensional tolerances among the many moving pieces. This can be addressed by testing 100% of a batch of pumps before they go out the door. What makes this easier is the ability to program digitally customizable motor control boards. Performance repeatability is then achieved more economically and efficiently.
Tailoring pumps to the exact requirements of customers is the core business of KNF. We’ve built a solid reputation for providing design engineering expertise and product flexibility. Contact us today to discover which digital customization options are available for your application.
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