3

BP7B Circuit Explanation:

A complete schematic of the

BP7B interface circuit is shown in figure

3 and the bill of materials is given in

Table 2. This circuit uses the VLA606-

01R to transfer logic level control signals

between the system controller and the

IPM. The internal optocouplers provide

galvanic isolation to completely separate

the controller from the high voltage in

the power circuit.

The BP7B also

provides isolated control power supplies

to power the IPMs built-in gate drive and

protection circuits.

The six main IGBT on/off control

signals

are

transferred from the system controller to

the IPM using the VLA606-01R. The

IPM’s active low control inputs are

pulled high by the VLA606-01R. An on

signal is generated by turning on the

internal optocoupler to pull the IPM’s

control input pin low.

The brake IGBT control signal (BR) is transferred from the controller to the IPM using a low speed opto-

coupler (IC1). The active low brake input pin on the IPM is normally pulled high by R1. When the BR control line

(Pin 6 of CN1) is pulled low, current flows in the LED of the brake isolation optocoupler turning on its output and

pulling the IPM’s brake pin low to activate the brake IGBT. If the IPM being used does not have the brake option

then IC1, R1, and R2 can be omitted.

The IPM’s fault output signals are transferred back to the system controller using low speed optocoupled

transistors internal to the VLA606-01R. During normal operation the fault feedback line (pin 9 of J2) is pulled

turn off the involved IGBT and pull its fault output pin low.

The IPM’s fault output has an open collector

characteristic with an internal 1.5k ohm limiting resistor. Current flows from the +15V local isolated supply to the

low speed optocoupler LED (inside the VLA606-01R) and then to the IPM’s fault pin.

The optocoupler’s

VLA106-24154

VLA106-24151

Figure 2: Isolated DC to DC

Converters for IPM Control Power

L-Series IPM

Connector

J2

+

C1

+

C2

+

C

+

C4

+V

J3

J1

R4

VLA106-24154/VLA106-24151

1 2 3

11

10

8 9

16 17

+

LED5

C5

IC12

IC5

IC4

IC3

R3

R2

IC1

IC2

IC6

R1

LED4

LED3

LED2

LED1

1

2

3

4

8

9

10

11

15

16

17

18

22

23

24

25

26

27

32

33

34

35

36

37

38

39

40