Fast-responding over current detector circuit in high voltage technology for motor drive applications

A monolithic over current detector for motor drive application in high voltage technology is here presented. The goal of the IC is the detection of different types of faults which can affect a triphase inverter used in motor drives applications. The over current condition is detected sensing a shunt resistor put on the DC+ bus of the inverter and is communicated to the DSP using an open drain output pin. The proposed IC represents an integrated and inexpensive solution, has a very simple structure and can be used in application with the inverter DC+ bus up to 600 V. The circuit is self-supplied and exploits the possibility to easily regulate the voltage threshold for the over current detection. The designed circuit and the most significant simulations are reported. The circuit has been diffused in a test chip: measurements demonstrates the validity of the proposed solution.