Most people have certainly been in the situation already, when suddenly and absolutely unexpected the electric device stopped working, because the battery power was used up. It can be a pure disaster for kids when their remote-controlled helicopter or drone does not work anymore because the battery has to be charged yet again. So always in the most inappropriate moment the electric screwdriver, razor or digicam goes belly up. Semiconductor companies like Infineon Technologies tackle such problems and offer devices and solutions for power management, consumption and voltage regulation.
A growing number of motion controlled applications, such as cordless power tools, industrial drives or electric bikes, are being built around brushless DC (BLDC) motors. This kind of motor needs more complex drive electronics than brushed alternatives. Nevertheless BLDC motors have quite some operational advantages that include higher efficiency and higher power density. Smart power management can have a tremendous impact on the efficiency of cordless devices and consequently extend their lifetime.
Critical Applications to Focus On
When it comes to cordless power tools and their increase in efficiency, engineers often focus on power management, motor control, battery management and the battery charger. In the battery charger and power supply for the motor drive block you can find IGBTs, such as high voltage MOSFETs (CoolMOS™) and low voltage MOSFETs (OptiMOS™). Infineon’s OptiMOS™ is optimized for synchronous rectification also for industrial applications like inverters. Moreover, for a more efficient power management control ICs for pulse-width modulation (PWM) and power factor compensation (PFC), Silicon Carbide Diodes, integrated power control ICs, DC-DC converters and linear voltage regulators come into play.
Interaction Between Switches, Sensors and Controllers
The BLDC motor is typically equipped with hall switches offering ‘1’ or ‘0’ outputs. Those give feedback about rotor position to the host microcontroller. These hall switches are necessary for applications such as cordless power drills where the motor needs to provide a high torque at or near zero speed. Hall switches, linear hall sensors and magnetic angle sensors based on giant magnetic resistor (GMR) technologies for current and position sensing and monitoring, as well as 8 bit- and 16 bit microcontrollers optimized for motor control applications, ensure stable and highly efficient control of the electric motor. The hall sensor signals are generated by hall switches integrated within the motor mechanical structure and are used by the microcontroller to trigger and apply the correct voltage on the appropriate phase.
Increase Efficiency and Shrink Product Designs
Modern semiconductor solutions help to achieve this in different ways. Infineon’s product portfolio is aimed to reduce power consumption of various cordless applications and are constructed to have more efficient product designs. In many cases MOSFETs are being used in parallel high current applications such as power tools, light electric vehicles and fork lifts. The result then is that a bigger board space is needed and therefore costs are rising. Infineon’s TO-Leadless MOSFET package is optimized to handle currents of up to 300 A, increasing power density with a substantial reduction in footprint. Together with a height reduction of 50% this results in an overall space saving of 60%. More compact designs can be developed with the use of this package.
Power Loss and Optimised MOSFET Selection White Paper
Among the challenges designers of BLDC motor applications facing is the delivery of optimum efficiency for a given price/performance point. Infineon’s recently published white paper will give the insight of detailed power loss analysis, quantify and explain where the losses occur including accurate identification of relevant losses in the power stage.
The 1kW evaluation board, which represents Infineon’s system solution for medium power BLDC motor control applications gives another example.