This application example replaces the four Y-capacitors, designated as CY5, CY6, CY7 and CY8 in Figure 9-1, with

a three-phase AEF circuit using the TPSF12C3. See Figure 9-2. The AEF circuit provides effective capacitive

multiplication of the inject capacitor, which reduces the inductance values to maintain the required LC corner

frequencies and thus the size, weight, and cost of the CM chokes, now designated as LCM1-AEF and LCM2-AEF.

The total capacitance of the sense and inject capacitors is kept less than or equal to that of the replaced

Y-capacitors, which results in the the total line-frequency leakage curernt remaining effectively unchanged or

reduced.

AC mains

Chassis (PE)

CX7

LCM2-AEF

RG

CG1

IGND

VDD

INJ

EN

COMP1

SENSE1

SENSE3

COMP2

REFGND

CINJ

CSEN1

CSEN3

3-phase

AC/DC

regulator

Chassis

CG2

CD1

RD2

CD2

RD3

CD3

CVDD

Chassis-referred

power supply

RD1

RD1A

SENSE2

SENSE4

TPSF12C3

= 3-phase AC/DC

= Three-phase AEF IC

DINJ

U1

From MCU

= Sense, inject capacitors

CSEN2

CSEN4

LCM1-AEF

CX8

CX9

CX4

CX5

CX6

CX1

CX2

CX3

CY1–CY4

= 3-phase source

3-phase AC

supply

Figure 9-2. Circuit Schematic of a Three-phase OBC With AEF Circuit Connected

9.2.1.1 Design Requirements

Table 9-1 shows the intended operating parameters for this application example.

Table 9-1. Design Parameters

DESIGN PARAMETER

VALUE

AC input voltage

230 V L-N or 400 V L-L (RMS)

AC input line frequency

47 Hz to 63 Hz

DC output voltage range

600 V to 1 kV

DC output current (max)

18 A

Rated output power

10 kW

AC/DC stage switching frequency

100 kHz

TPSF12C3

SNVSCB8 – MARCH 2023

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