Diodes Incorporated Brushed and Brushless DC Motors
Brushed DC motors are composed of a rotor with electromagnets and a stator with permanent magnets. The graphics below illustrate the construction and operation of a simple two-pole brushed DC motor works.
- The rotational speed of a DC motor is proportional to the back EMF across its coils.
- Torque is proportional to current.
- When the voltage remains constant an increase in load (torque) on the motor results in a decrease in speed.
- The relationship between speed and torque is shown in a motors speed - torque (below). Torque and speed are said to be inversely proportional.
Super Barrier Rectifier (SBR®) combines both a lower forward loss compared to a Schottky Barrier diode (SBD) with thermal stability of a Fast Recovery diode (FRD)
These advantages over existing technologies translate to…
- Higher Efficiency and Higher Temperature Operation
- SBR® enables lower VF with more stable reverse leakage current allowing applications to run more efficiently at higher ambient temperature, resulting in more power savings and higher reliability
- Better Performance in Smaller Packages
- SBR® patented high density cellular technology enables SBR® to exceed customers’ ever increasing demand for high performance in smaller packages
- Scalable technology
- Lack of metal Schottky barrier and use of CMOS process allows for a scalable technology from 0.1A to 60A and 20V to 400V without degradation of performance
Device Structure and Operation of SBR®
- SBR® is Patented and Proprietary Technology of Diodes Inc.
- Traditional (two terminal) device by shorting the gate and source together (shown in red)
- In forward mode, device operates as majority carrier (MOS) with low VF and fast switching
- In reverse mode, electrostatic behaviour causes depletion mode, substantially reducing leakage current
- Cellular design operates as thousands of individual devices working in parallel
Brushless DC Motors (BLDC)
- Improved battery performance suited for hand held power tools
- Government standards requiring more efficient energy usage
- 60 to 70% of industrial electricity usage is in motor drive
- All BLDC motors require electronic control to drive the motor
- Diodes Inc. offers Gate Drivers, MOSFETs, Hall Sensors, discretes
3-Phase BLDC Motor Driving Example
DMT Shielded Gate Technology
This MOSFET is designed to meet the stringent requirements of Automotive applications. It is qualified to AEC-Q101, supported by a PPAP.
Features
- Rated to +175°C – Ideal for High Ambient Temperature Environments
- Thermally Efficient Package for Cooler Running Applications
- High Conversion Efficiency
- Low RDS(ON) – Minimises On-State Losses
- Low Input Capacitance
- Fast Switching Speed
- <1.1mm Package Profile – Ideal for Thin Applications
