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IR2137: 3-PHASE GATE DRIVER WITH INTEGRATED IGBT PROTECTION

International Rectifier has now introduced the IR2137 to the AC drives market. This latest High

Voltage Integrated Circuit provides a monolithic solution to driving all six IGBT gate drivers, while

simultaneously providing full IGBT protection and soft shutdown. In contrast to the Floating Ground

Reference architecture discussed in the previous section, the IR2137 circuit enables a simple struc-

ture. The differences between the two architectures are summarized in Table 2.

Floating Ground System

IR2137 solution

Gate Drive

Six Fast Optical Isolators

IR2137

IGBT Protection

Two Hall Effect sensors and

IR2137 integrated function with a

Two comparators

shunt resistor and a comparator

Four floating power supplies

Eliminated (boot strap power)

Additional Circuits

Snubber circuit or discrete soft

Eliminated by integrated soft shutdown

shutdown circuits

function

Brake IGBT drive circuit with

Eliminated by integrated brake IGBT

an optical isolator

driver circuit

Table 2: Solution Comparison of Gate Drive and IGBT Protection

For the IR2137 circuit, as shown in Figure 5, the IR2137 and a micro-controller (

µC) share the same

ground potential – the negative DC bus potential. (This architecture is already the industry standard

in the micro AC inverter drive segment). Unlike its traditional counterpart, the IR2137 circuit requires

a single shunt resistor and associated comparator. With this, it can perform all modes of IGBT short

circuit protection.

Additionally, the IR2137 contains IGBT de-saturation logic in the circuit of each high-side gate drive,

as shown in figures 6 and 7. In the event of a Ground Fault condition, the DESAT pin is activated, and

the fault signal is transferred to the low side fault logic circuit. The low side fault logic then initiates the

simultaneous soft shutdown of all 6 IGBTs. When the soft shutdown signal is transferred back to the

high side, the active PMOS/NMOS transistor buffer goes into a high impedance mode and another

weak NMOS transistor becomes active to slowly drive the gate pin low. The shutdown softness can

be programmed by adding an external resistor to the SSD pin – thus allowing the user to optimize

softness for the specific gate charge of the IGBT. To eliminate the dv/dt induced false triggering of the

DESAT pin, there is a blanking filter delay of 2 microseconds at each high-side gate turn-on transi-

tion.

Figure 8 shows the oscillogram of the ground fault protection feature in the IR2137. In this measure-

ment, a size 4 IGBT, IRG4BC40KD, was used in conjunction with a turn-on resistor, Rg = 33

Ω, turn-

off resistor, Rg = 16

Ω, and soft turn off resistor, R

Ω. The top trace in Figure 8 is the IGBT

IGBT short circuit current (40A/div). No snubber circuit was used for this test. One can see that the

de-saturation protection activates quickly and the soft shutdown feature virtually eliminates the over-

shoot voltage across the collector and the emitter.