Open Loop Speed Control of BLDC motor using Snetly
Welcome to LMS Solution! In today's session, we will explore the concept of open-loop speed control for a Brushless DC (BLDC) motor using the Snetly modular real-time system.
Hardware Overview
The hardware unit of Snetly consists of interfacing digital input and output, an analog signal area, and an in-built gate drive circuit for digital outputs ranging from 0 to 15 volts. The demonstration involves connecting a three-phase BLDC motor, utilizing feedback from the motor's Hall signals for control.
Key Hardware Components:
Digital Input: Three Hall signals (HALL-A, HALL-B, HALL-C) with a 120-degree phase shift.
Current Sensor: Measures three-phase current of the BLDC motor.
Voltage Source Inverter: A two-level inverter directly connected to power semiconductor switches.
Power Supply: Utilizes a 24V DC supply for the 24V BLDC motor.
Model-Level Design
The model-level design is developed to run the motor in an open-loop speed control configuration. Since the BLDC motor is sensor-based, feedback from the Hall sensors is crucial. The model includes configurable lookup tables to generate gate signals for the voltage source inverter. A dead time controller is employed for each leg of the inverter.
Configuration Parameters:
PPR (Pulses Per Revolution): Configured as four for the motor.
Dead Time: Configured as one microsecond.
The model generates six gate signals for the six-step commutation (120-degree mode of operation). These signals are directly connected to the digital output pins with the in-built gate drive circuit.
Demonstration
Hardware Connection: Connect the hardware unit as per the model-level design.
Run Simulation: By varying the duty control, observe the motor starting to run.
Observations:
Hall sensor feedback with a 120-degree phase shift.
Gate signals shown in the logic analyzer.
Current waveforms for each phase of the BLDC motor.
Adjusting Motor Speed: Vary the duty control to observe changes in motor speed.
Load Testing: Apply a load to the motor and observe the corresponding increase in current waveform.
Motor Speed Control: Demonstrate speed control by adjusting the duty cycle.
Conclusion
The open-loop speed control of the BLDC motor using the Snetly modular real-time system provides a real-time, hardware-in-the-loop demonstration. The system's flexibility, ease of use, and direct integration with digital outputs make it a powerful tool for motor control applications.
For more information and in-depth insights, subscribe to the Snetly YouTube channel and LMS Solution. Visit snetly.in for direct contact with application engineers and sales personnel at Snetly.
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