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IRMDAC4

System Description

The IRMDAC4 is the AC motor reference design kit for

the IR2137Q 3-phase gate driver IC and the IR2171

current Sensing IC. It is the power conversion unit for

a 3-phase/230V 3HP (2.2kW) AC PWM (Pulse Width

Modulated) drives. This design kit consists of the

IR2137/IR2171 power board based on 4-layer PCB.

The ECONOPIM2 power module and the heat sink are

supplied separately. User must provide soldering con-

nection between the power board and the power mod-

ule, and the appropriate heat sink to complete the power

conversion function.

Figure 1 shows the complete assembly of the

IRMDAC4 Reference Design Kit. Figure 2 illustrates

the typical connection block diagram of the IRMDAC4.

The IR2137/IR2171 power board contains an IR2137Q

gate driver High Voltage IC, DC link capacitors, soft

start function using NTC thermistor, AC input MOVs

for surge suppression, switching power supply, brake

IGBT buffering circuit, over-current/ground fault/over-

temperature protection circuit, DC bus voltage and

current feedback signals. On-board 16-pin single row

header connector (J9) is provided to interface the con-

trol signals, and two terminal blocks are provided to

facilitate connection to 3-phase AC input (J7) and out-

put (J6).

The power module contains a 3-phase input bridge

rectifier, 3-phase IGBT inverter; brake IGBT/diode, and

the temperature thermistor on the substrate base. It is

designed for easy mounting to a heat sink.

Output power is PWM 3-phase, variable frequency and

voltage controlled by a user provided 5V PWM signal

input. The limited amount of the power is available for

two 5VDC (one ground isolated and one non-isolated),

and 15VDC non-isolated to facilitate the PWM inter-

face. The non-isolated powers are referenced to the

negative DC bus that the IR2137Q gate driver IC is

also referenced to.

The IRMDAC4 offers several benefits to the users listed

below:

•

It gives a complete working reference of the 3HP

AC drive power conversion based on the state-of-

art 3-phase gate driver and IGBT power module.

User can gain immediate hands-on experience

based on the system. The design detail can be

further utilized in the area of: PCB layout, gate drive

optimization, protection circuit, and on-board

switching power supply.

•

Gate drive and protection circuits are designed to

closely match the operating characteristics of the

power semiconductors. This allows power losses

to be minimized and power rating to be maximized

to a greater extent than is possible by designing

with individual components.

•

It reduces the effort of calculating and evaluating

power semiconductor losses and junction tempera-

ture.

IR2137 Driver Board

The IR2137/IR2171 power board also contains the

feedback signal circuit, brake driver, soft start circuit,

and the local switching power supply. The driver also

interfaces to the AC input line. It houses the DC link

capacitors, current sensing shunt resistor, NTC in-rush

limiting thermistor, and surge suppression MOVs.

The inverter gate drive circuits, implemented with an

IR2137Q monolithic 3-phase HVIC driver, delivers gate

drive to the IGBTs corresponding to PWM control sig-

nals HIN1 through HIN3, and LIN1 through LIN3 into

J9 connector. It introduces a 0.2

tween upper and lower gate signals for each phase.

Any additional deadtime necessary to expand must be

included in the PWM signals. Gate drives must be

enabled with an active low pulse applied to the RESET

pin into J9 pin 14 while PWM inputs HIN1 through HIN3,

and LIN1 through LIN3 are held high (off condition).

After power up, the RESET pin must be pulled low

before any input signals are activated.

The protection circuitry of the system is incorporated

by two means: One is by the function of the high side

de-saturation protection input (DESAT) in the IR2137Q

IC, and the other is by the comparator circuit and cur-

rent sensing shunt resistor (R44) for the low side gate

driver that enables the ITRIP input of the IR2137Q

device. The internal fault logic of the IR2137Q will

enable the FAULT output in an event of a short circuit,

earth/ground fault, over-temperature, or over-voltage/

over-current conditions with Soft Shutdown, as speci-

fied. Over-current signals are sensed through shunt

resistors located in the negative DC bus rail. Earth/

ground faults are sensed using the high side shunt re-

sistor and the signal is level shifted through the opto-

isolator to the protection circuitry. Over-temperature

protection is obtained using a thermistor inside the