Issue link: https://resources.mouser.com/i/1442844
19 Qorvo 2021 The challenge was to continue using a potentiometer to control tool speed without passing the high current through its resistive component. As we will see later, this is a relatively simple fix. The motor, on the other hand, proved to be a far more substantial and complex challenge. Early in power-tool development, the motor employed was either a brushed universal AC/DC motor for corded tools or a brushed DC motor for cordless tools (Figure 1). Because both motor topologies are brushed in nature, motion is obtained by using carbon brushes to pass a current into a copper commutator, generating an internal revolving magnetic field. By placing the electromagnet winding along with the commutator in the rotor, and the permanent magnets in the stator, we obtain two magnetic fields continuously fighting each other and causing the motion we need. Unfortunately, this comes at the cost of considerable friction between the brushes and the commutator. The friction is considerable, and after prolonged use, the motor will eventually destroy itself. This friction is energy wasted in the form of heat. That is energy that flowed out of the power source and did not generate any useful work. Systems revolving around this topology give an efficiency no higher than 80 percent (in the best-case scenario). This means 20 percent of the energy inside of the battery is used to generate heat. When trying to make holes with a battery-powered drill, using a fifth of your power source to generate heat does not sound very appealing. PAC5527 48V Charge Pump and Programmable Driver Motor Controller LEARN MORE > Figure 1: Brushed DC motor. (Source: Qorvo).