Industry Article

Modern Approach to the Electrification of Consumer Outdoor Power Tools

August 12, 2022 by Joe Roy, Infineon Technologies

The consumer outdoor power tool market is becoming increasingly electrified, and new design decisions are facing companies and consumers alike. Learn more about the future of outdoor power tool design.

The consumer outdoor power tool market is becoming increasingly electrified, and new design decisions are facing companies and consumers alike. For example, cordless power tools, such as lawnmowers (shown in Figure 1 below) and trimmers, involve a far more modern approach than just including a battery. And there exist several critical challenges related to these designs, including efficiency, weight, safety & security, and cost.

 

Figure 1. Cordless outdoor tools use batteries, but the approach to a good design is far more complex than just switching the power supply to batteries. Image provided courtesy of Canva.

 

Efficiency

One of the overarching goals for cordless consumer power tool design is improved power density, which is closely coupled with efficiency. Inefficiency manifests as power loss, and power loss takes the form of unwanted heat; excessive heat generation limits the tool's intended power in a given volume, increases cost/complexity, and can cause safety issues. 

This type of inefficiency can also heat the tool to the point that it becomes uncomfortable and problematic for the user, which can be exacerbated on outdoor tools by high ambient temperatures and direct sunlight. In addition, these problems are further compounded when the motor control electronics are installed inside or attached to the motor itself.

Fortunately, there are various ways to maximize efficiency and minimize thermal issues. Such methods include implementing high-performance MOSFET packaging with advanced Silicon die and gate drive technology. Using wide bandgap (WBG) transistor technologies, such as gallium nitride (GaN), is now also on the horizon as a solution that will allow more efficient power delivery to the tool’s motor.

Additional efficiency enhancements may be possible by optimizing battery protection circuitry, transistor switching (Eon+Eoff), and transistor conduction (RDS(on)). Maximizing torque per amp through optimized Field-Oriented Control algorithms may also be considered.

 

Safety and Security

When consumers use unapproved, third-party batteries and chargers, there is no way to guarantee the tool's and battery's safe, predictable performance. Many third-party batteries and chargers are not correctly rated or tested to ensure their safety. A properly engineered and tested outdoor tool must consider all combinations of BMS (Battery Management System) and charger/tool electronics. One solution to this issue is battery authentication, which verifies that the battery used is a legitimate product and intended for use with the tool. 

Another aspect of safety and security lies in firmware updates, supporting new features, safety improvements, and performance tweaks during the life of the tool. Firmware update mechanisms must be engineered with cybersecurity in mind. A failure to address these risks can lead to dangerous situations and compromised performance. 

 

Figure 2. Even cordless outdoor power tools can pose security risks that must be addressed. Image provided courtesy of Pixabay.

An excellent approach to ensuring cybersecurity when updating firmware on a tool’s microcontroller is to use Infineon’s OPTIGA™ TRUST solutions. These are miniature cryptography-based authentication components that ensure updates coming from the cloud are genuine and that they are applied only to the tools for which they were intended.

 

Cost

For handheld indoor power tools, some consumers shy away from the increased cost associated with quality, peak performance, and high-reliability motor control components. However, with outdoor tools that involve a significantly higher investment for both the tool and the battery, consumers are willing to pay more for a power tool that promises more efficiency, unquestioned reliability, longer run times, and longer lifespan batteries.  

Most consumer-oriented tools use 4V to 20V battery systems, while outdoor power tools target 60V to 100V batteries, which are more expensive due to the larger motor sizes that demand more power. However, these higher voltages lead to less optimal MOSFET performance, making it critical to take advantage of the latest power semiconductor technology to ensure the many gains achieved by the more expensive battery packs are not lost in the battery and motor-control circuitry.

A cost-effective tool, regardless of size, requires the right combination of microcontrollers, MOSFETs, gate drivers, power supply components, sensors, and more. Being cost-effective is not only about the bill of material (BOM) cost for the electronics components; it also involves the extra expense related to using lower-performance components. For example, is it logical to use ultra-low-cost, low-performance MOSFETs if it means the heat sink has to be larger, the motor material cannot be maximized for peak torque, or the battery's total capacity cannot be put to good use by the application?

Although more expensive than their silicon cousins, gallium nitride (GaN) transistor technology may soon find its way into power tool designs due to its exceptional efficiency, compact size, and ability to drive next-generation motors. New GaN and silicon carbide (SiC) technologies are rapidly transforming the high-power chargers used with these tool batteries, leveraging their efficiency gains into small, rapid-charging form factors.

 

Infineon Cordless Power Solutions

Infineon has a line of products explicitly designed to address the challenges of demanding high-power outdoor tools such as those represented by the block diagram shown in Figure 3. 

 

Figure 3. Application block diagram for cordless power tools. Image provided courtesy of Infineon.

 

On the control and intelligence front, Infineon offers a wide range of industrial and IoT microcontrollers, supporting advanced motor control algorithms and an array of connectivity options that include USB, BLE, WiFi, and CAN. Additionally, Infineon provides access to the latest motor control algorithms in discrete and compact single-IC microcontroller (MCU)+Drivers, like the MOTIX™ IMD700 family. 

On the power semiconductor side, Infineon has a portfolio of industry-leading solutions focused on improving battery and motor efficiency/performance, such as optimized MOSFETs, gate drivers, current sensors, and USB power delivery ICs. 

 

Conclusion

Infineon has a reliable history of providing industry-leading semiconductor packaging, die, and firmware solutions. Infineon also takes security very seriously as the world's largest supplier of security solutions inside chip cards. With its full range of product offerings, Infineon enables efficient, robust, and modern power tool designs to support any work environment. Contact us to learn more about our solutions for consumer power tools.