Overcoming Design Challenges: Brushless DC Motors and Drives
September 23, 2024
Try to think of a time when you didn’t use an electric motor of some kind. From the ceiling fan in your home to the windows in your car to delicate surgical instruments in a hospital, electric motors are a cornerstone of modern technology. They consume more than half of the world’s electricity. Increasing energy efficiency can significantly reduce global electricity demand. The best-performing motors use smart control.
Qorvo Staff Applications Engineer José Quiñones' 2024 white paper, "Design Challenges and Considerations for Brushless DC Motors and Their Drives" offers a close look at the challenges and benefits associated with Brushless DC (BLDC) motors. “Motors have been used for the last 100 to 150 years,” Jose said. “As you can imagine, at first, they were incredibly simple. Just connect them to a power source, and they would work. It wasn't the most efficient way of performing a motorized task, so you can imagine the demands placed on these motors over the last century. They’ve had to get much more sophisticated, and so did the devices that control them.
“For the past 12 years, what we've been doing is integrating motor control into a single chip to make the application much smaller. By doing that, you can also save on cost. Some applications actually need a small space footprint because if you think of a battery-operated drill, all the space that you have is basically in the palm of your hand. That’s where a lot of design challenges come into play. But if you meet those challenges, the benefits are many.”
Design Challenges
- Initial Costs
- Higher upfront costs for BLDC motors and their drives compared to traditional motors.
- Integration of advanced control electronics adds to the initial investment.
- Complex Control Systems
- Need for sophisticated control algorithms to optimize performance.
- Requires significant processing power and advanced software for optimal operation.
- Motor Selection
- Choosing the right motor type based on application requirements (e.g., continuous vs. intermittent torque and speed).
- Ensuring compatibility with existing systems and performance expectations.
- Sensor Integration
- Deciding on the type and placement of sensors for accurate rotor position detection.
- Balancing cost and performance with different sensing technologies (e.g., Hall effect sensors and optical encoders).
- Heat Management
- Effective dissipation of heat generated by power electronics and motor operation.
- Maintaining performance and longevity under varying operational conditions.
Benefits of BLDC Motors
High Efficiency
- Potentially over 96% efficiency, leading to significant energy savings.
- Lower lifecycle costs due to reduced electricity consumption.
Long Lifespan
- Minimal maintenance requirements as there are no brushes to wear out.
- Durability and reliability in various applications.
- Compact and Lightweight
- Higher power density allows for more compact motor designs.
- Ideal for applications where space and weight are critical factors.
- Enhanced Performance
- Precise control over speed and torque with advanced drive electronics.
- Smooth operation and reduced torque ripple, especially with sinusoidal commutation.
- Versatile Applications
- Suitable for a wide range of applications, from small handheld tools to large industrial machines.
- Flexibility in operation with both battery-powered and main-powered systems.
Qorvo BLDC Motor Control Solutions
Jose says in order to make use of all of this capability, there has to be a way to control the different electrical parameters of the motor. “All of these things require a lot of handholding, and that is where the motor controller comes into play. In this case, the one we provide has a microcontroller that houses the required intelligence.”
Qorvo offers integrated solutions to address the challenges of BLDC motor control. Their PAC5xxx series Power Application Controller™ (PAC) integrates all necessary functions for BLDC motor control:
- High Integration: Combines three-phase gate drivers, power management, analog front end, multiple communication interfaces and sensor interfaces.
- Configurable and Updateable: Allows for field updates and auto-tuning for specific motors. Comprehensive Protection: Includes over-current, under-voltage, over-voltage and over-temperature protections
- Space and Cost Efficiency: Minimizes board space requirement, as well as component count, reducing BOM and assembly costs.
The PAC series simplifies the implementation of BLDC motors, ensuring high performance, efficiency and reliability across various applications.
“For safety, we created a new line of drivers that have two features. We took these safety measures from the realm of software and moved them to hardware. Now you have a hardware implementation that allows the motor to be stopped quickly and the power stage to be disabled with hardware, as opposed to firmware. This ensures potential firmware glitches cannot interfere with and compromise safety. Allowing for redundancy increases safety on some power tools for which safety is paramount. For example, chainsaws!”
BLDC motors, despite their initial cost and complexity, offer unmatched efficiency, longevity and performance benefits. By overcoming design challenges with integrated control solutions like Qorvo’s PAC series, industries can achieve substantial energy savings and operational improvements. “Our tools make designers’ lives easier,” Jose said.
Learn more in Jose’s white paper "Design Challenges and Considerations for Brushless DC Motors and Their Drives."
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