Industry White Papers

Use of BridgeSwitch Current Sense Signal Output in Field-oriented Control of BLDC Motors

September 03, 2020 by Power Integrations

High-performance motor drives commonly use field-oriented control since it offers smooth and efficient operation throughout the entire speed range. BridgeSwitch offers a unique function by providing a small signal output that is an instantaneous representation of the positive phase current.

This function of BridgeSwitch can eliminate commonly used discrete current sense resistors and associated amplifiers, thereby reducing cost and design complexity. A proposed algorithm allows using the small signal output provided by each device through directly measuring, reconstructing, and predicting the full phase current information in 3-phase motor drives utilizing FOC where the motor provides the rotor position information.



BridgeSwitch devices offer an integrated phase current (IPH) output signal. The IPH output provides a small signal current; proportional to the instantaneous-channel current flowing thru the low-side FREDFET (the output does not provide a signal when the diode is conducting). This eliminates the need to add a DC offset to the measured motor current.