Orient Intelligent IGBT Driver Optocoupler Products Introduction

Ray Wang    [email protected]    www.orient-opto.com

 

1.IGBT Driver Introduction

In the electronic power system, the IGBT drive circuit is a very crucial component. As the interface circuit between the module and the single-chip microcomputer, it needs to convert the signal from the single-chip microcomputer into a drive signal with sufficient power to ensure the safe on and off of the IGBT and provide electrical isolation between the two. In order to ensure that the IGBT is correctly and effectively protected when a system failure occurs, a separate protection circuit needs to be designed for the conventional IGBT drive circuit.

The Orient intelligent IGBT drive optocoupler (OR-3120) is a device that integrates VCE detection, under-voltage locking (UVLO), "soft" turn-off of IGBT, isolated collector open circuit fault feedback and active Miller clamping on the basis of the conventional IGBT drive circuit. The intelligent gate-level driver inside makes the fault protection of the IGBT's VCE more compact. Due to its built-in protection function in the circuit, it provides the greatest design flexibility for designers.

 

Conventional IGBT drive circuit - OR-3120

 

2.The applications:

● Frequency converter and power system

● Automotive electronic system

● Industrial automation and control systems

● Wind power and solar power generation systems

 

OR-332J recommended application circuit

 

3.Internal Principle of Orient Intelligent IGBT Drive Optocoupler

 

Schematic diagram of the internal circuit of OR-332J

 

Pin description of OR-332J

 

IGBT "soft" turn-off: When the system is operating normally, Vout is controlled by the drive current of the optocoupler OR-3120, and the VCE value of the GBT is monitored simultaneously. At this point, the Fault pin outputs a high level. If there is a short circuit or a large current flowing through the IGBT, the IGBT enters the undersaturation mode and the VCE voltage rises rapidly. When the DESAT pin detects that the voltage value of VCE is higher than that of VDESAT, Vout gradually becomes a low level and begins to soft-turn off the IGBT to prevent high voltage caused by di/dt. At the same time, the feedback channel inside the optocoupler is triggered to pull down the Fault output. During the IGBT turn-off period, CBLANK discharges and the fault monitoring circuit is set to invalid to avoid generating incorrect fault signals. Once the fault status is detected, Vout is disabled for at least 5us. During the disabling period, ignore all input drive signals to enable the driver to completely soft-turn off the IGBT. After the disabling time has passed, the input drive signal on the primary side becomes high again, making the fault monitoring circuit effective once more.

Blank-out time TBLANK: Immediately following the conduction of the IGBT, the DESAT fault monitoring circuit needs to be shielded for a short period of time to allow the collector voltage to drop below the DESAT threshold. This time is called the DESAT blank-out time. It is controlled by the internal charging current ICHG of the DESAT, the DESAT voltage threshold VDESAT and the external capacitor CBLANK:

TBLANK=CBLANK x VDESAT / ICHG

The nominal blank time using the recommended 100pF capacitor is TBLANK=100pF*6.5V/240uA=2.7us;

Under-voltage locking: The under-voltage locking feature is designed to prevent insufficient driving voltage at the IGBT gate. The typical gate voltage required by IGBT is 15V. When the gate voltage is lower than 13V, the VCEON value increases sharply, especially at high currents. When the gate voltage is lower than 10V, IGBT operates in the linear region, which will cause a sharp increase in the power consumption of the module. If VCC2 exceeds VUVLO+ (the positive threshold voltage for under-voltage locking), the embedding release of the under-voltage locking module allows the optocoupler OR-3120 to operate normally. If VCC2 is lower than the threshold VUVLO-(undervoltage locking negative threshold voltage); The under-voltage locking module works, lowering the output of the optocoupler. Before VCC2 reaches VUVLO+, the DESAT protection circuit is already effective. Therefore, the under-voltage locking and DESAT fault detection circuits work together to protect the IGBT.

 

4.Typical model:

The following models of Orient intelligent IGBT drive optocouplers are available for selection:

OR-316J, OR-331J, OR-332J, OR-333J, OR-337J, etc.

 

Physical diagram of OR-332J optocoupler

 

Ray Wang    [email protected]    www.orient-opto.com