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IPM Internal Feature Mechanism
- Aug 20, 2018 -

IPM built-in driving and protect circuits makes simple and reliable hardware, shorten the development time of the system, also raised the failure of protection. Compared with conventional IGBT modules, IPM in the performance and reliability of the system has been further improved.


Undervoltage protection circuit can control voltage protection, overheat protection, overload protection and short-circuit protection. If there is a protection circuit in the IPM module, IGBT gate drive unit will shut off gate current and a fault signal output (FO). Various protective functions as follows:


(1) control voltage under voltage protection (UV): IPM uses a single +15V the power supply, if the supply voltage is less than 12.5V, and for more than tOFF=10ms, under voltage protection, blockade the gate drive circuit, the output signal.


(2) the overtemperature protection (OT): near the IGBT chips on the insulating substrate a temperature sensor is installed when IPM temperature sensors measure the temperature of the substrate when the temperature is exceeded, over temperature protection, blockade the gate drive circuit, the output signal.


(3) overcurrent (OC): If IGBT current value than current actions current and longer than tOFF, overcurrent protection, blockade the gate drive circuit, the output signal. To avoid excessive di/dt, most of the IPM uses two-stage shutdown mode. Where VG is the Department within the drive voltage, short circuit current ISC, IOC is current value of over, IC is collector current, IFO fault output current.


(4) short circuit protection (SC): If the load event of a short circuit or control system failure caused a short circuit, current flowing through IGBT short circuit current over, then immediately short circuit protection, blockade the gate drive circuit, the output signal. As with overcurrent protection, to avoid excessive di/dt, most of the IPM uses two-stage shutdown mode. To shorten the current over-current detection and response time, IPM uses real-time current-control circuitry (RTC), so that response time is less than 100ns, thus effectively suppresses the peak currents and power, increased protection.


When the IPM UV, OC, OT, SC any faults in time, the fault output signal duration tFO 1.8ms (President of the SC duration), this time, IPM will blockade the gate drive, the turn-off IPM fault duration after the end of the output signal, IPM can reset automatically, open gate drive channel.


As can be seen, the fault signal device itself is maintained, if tFO fault source still has not ruled out at the end, IPM will repeat the process of automatic protection, repeated actions. Overcurrent, short circuit, overheating protection is very poor operating conditions, repeated action should be avoided, so IPM internal protection alone cannot fully protect themselves. To make the system truly secure, reliable operation, supplementary need of external protection circuit.