UM0969 datasheet(12/46 Pages) STMICROELECTRONICS

12 / 46 page

Board description

UM0969

12/46

Doc ID 17665 Rev 2

2.3

Circuit description

2.3.1

Power supply

Power supply of the STEVAL-IHM027V1 is realized as a multifunctional block which allows

the inverter to be supplied up to +350 V.

The auxiliary power supply, needed for the active components on the demonstration board,

is implemented with a buck converter based on U10 VIPer16, which works with a fixed

frequency of 60 kHz. The +15 VDC output voltage is fed into VCC (STGIPS10K60A, PIN 5),

as well as into the linear regulator L7805ICP, which provides a +5 VDC for supplying

operational amplifiers and further related parts. The presence of +15 VDC on the board is

indicated with a green LED (D1).

Please refer to the VIPer16 datasheet (see References 2) for further information. Figure 5

below describes the power supply block diagram.

Figure 5.

STEVAL-IHM027V1 power supply block diagram

2.3.2

Inrush limitation

The input stage of the demonstration board is provided with an NTC resistor (RT1) to

eliminate input inrush current peak during bulk capacitors charging. It is possible to achieve

a higher inverter efficiency to bypass this resistor after the startup phase. The driving signal

of the bypassing relay is provided directly from the MCU board through the J3 motor control

connector (pin 21).

2.3.3

Brake function

A hardware brake feature has been implemented on the STEVAL-IHM027V1. An external

resistor can be connected to the board thanks to the J4 connector. It represents a dummy

load connected directly to the bus, in order to eliminate any overvoltage condition generated

by the motor operating as a generator.

Voltage on the bus is sensed through a voltage divider net (resistors R80, R81, and R82),

and it is compared to the voltage reference of U6.

The brake dummy load is switched on when the bus voltage reaches 390 VDC and switched

off when the voltage decreases to below 330 VDC.

UM0969 датащи(PDF) 12 Page - STMicroelectronics