Application of MOSFET in driving motor power
The most important performance requirements for driving the power stage of the motor are small size, high efficiency, good thermal performance, reliable protection, and high peak current carrying capacity. The small size allows flexible installation of power levels within the tool, better board layout performance and low-cost design. High efficiency provides the longest battery life and reduces cooling. Reliable operation and protection extend slonge and help improve product reputation.
To drive the BDC motor in both directions, you need to use two half bridges (four metal oxide semiconductor field effect transistors (MOSFET) to form a full bridge. To drive a three-phase BLDC motor, three half-bridges (six MOSFETts) are required to form a three-phase inverter.
The three-phase BLDC motor with only three power modules is driven in two directions, with two MOSFETs (high and low MOSFET) connected to each power supply to form a half-bridge.
The power block of two FETs integrated in the same package allows for a reduction in the three-phase PCB area for inverter topology, the MOSFET interconnect track will operate in a PCB with discrete MOSFET, and higher operating currents require a wider PCB track, so size savings are also available.
One of the reasons for ringing is that the diode is restored in reverse. High current change rates caused by fast switches can cause high diodes to reverse recovery current. Reverse recovery current flows through the parasitic layout inductance. The resonance network formed by FET capacitors and parasitic inductors causes phase node ringing, reducing voltage margin and increasing the stress of the device
When using a power supply, a switch node clip with two MOSFET slots that connect the two MOSFETs keeps the parasitic inductance between the high and low-side MOSFETs at an absolute minimum. Using low-side and high-side FETs in the same package minimizes PCB parasitics and reduces phase node voltage ringing. Using these power modules helps ensure smooth drive MOSFET switches without voltage overshoot even when currents are up to 50A.
The power module has a top and bottom MOSFET in a single package, as well as phase nodes connected via a metal clip in the package, optimizing parasitic resistance and providing flexibility for layout, saving minimal total PCB resistance of 0.5 to 1mΩ.