The protection circuit comprises two protections: undervoltage and overcurrent. Overcurrent protection is intended to protect the circuit (especially the IGBTs – but also the tracks, connectors, power source) which are theoretically dangerous countercurrents and which generally indicate inadequate system operation (short circuit, Attempt to break the engine at high speeds, etc.).
The operation is based on the measurement of the voltage in resistors installed in series in the circuit (called “shunt”). The measured signal is amplified by op-amps and later equated with a reference set by the user. When the measured current exceeds the reference, the comparator changes state and the protection is preserved activated by the action of a flip-flop, until the user restarts the protection.
Because overcurrent protection is performed via hardware and fast components, it acts very quickly and efficiently. The adjustment of the actuation current is carried out by the user through a trimpot.
Once the limit is exceeded, in either arm of the inverter, the protection will act in a few microseconds. This protection works in addition to thermal protection.