Intelligent Power Module for DC-DC Converter

Chapter 1 Introduction

1.1 Technical Specifications

1.2 Block Diagram

1.3 Detailed Features of Driver Card

1.4 Design of DC-DC Boost Converter

Chapter 2 Pictorial View

2.1 Connection Details

2.2 Part Number of Different Components Used

Chapter 1 Introduction

Intelligent Power Module for DC-DC Converter is developed with protection mainly for integration of renewable energy sources. The unit can be used for experiments on Boost Converter, for development of MPPT algorithm and as input stage with single phase grid synchronized inverter.

1.1 Technical Specifications
Intelligent Power Module for DC-DC Converter is provided with the following Specifications -

• Input Voltage: 100 to 200 V DC

• Maximum Output Voltage: 350V

• Maximum Power: 1 kVA

• Operation in internal and external mode.

• In internal mode switching frequency 120 kHz is internally generated through PWM IC and duty ratio can be manually adjusted using pot.

• In external mode, 0-5 V gate pulses generated by external microcontroller can be connected.

• 900 V, 25 A SiC MOSFET as switch

• 1200V, 30 A ultra-fast diode

• 500 micro Henry inductor and 470 micro Farad capacitor

• Driver IC with desaturation protection against overload and short-circuit

• Indication of READY and FAULT with a provision to latch driver output and RESET button.

• All cards are mounted in Transparent Acrylic box and power terminals, control terminals and sensor feedback are terminated on front panel.

1.2 Block Diagram
The block diagram of the unit is shown in following figure. Dotted parts are to be connected externally. Gate pulses generated by any controller can be used to control the power hardware. The sensor circuit output can also be fed to external controller for feedback.
d1

1.3 Detailed Features of Driver Card

The driver card is designed with Infineon Driver IC 1ED020I12-F2. The distinct features are:

• Suitable for 1200V, 25 A MOSFETs

• 2 A rail-to-rail output

• Individual 02 channel isolated MOSFET driving

• Input pulses: CMOS 0-5 V or 0-3.3 V (Active high pulse)

• Output pulses: Isolated +16V/0V

• Shoot through, Short circuit protection with DESAT-detection

• On board hardware dead time generator circuit (1 µSec)

• 02 SMPS for generating +16V/-8V isolated power supplies required for driver IC

• Inhibiting all gate pulses during any abnormality/hardware error/FAULT condition

• RESET to start gate pulses after clearing the FAULT. Driver can be RESET via on board

switch or external reset pulse.

1.4 Design of DC-DC Boost Converter
The output characteristic of the boost converter is described by following equations.

d2

where, Vo and Io are output voltage and current of the boost converter; Vpv and Ipv are the input voltage and current; and Rin and RL are the input impedance and the load resistance of the boost converter.

There are two modes of boost converter operations, the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM). In the CCM, the inductance current is always positive and the mode is suitable for high efficiency and better utilization of the semiconductors switches and the passive components.

The inductance L works as a filter to smooth the input and output current of the converter. Lbo is the limiting value of L for a specified duty cycle α and chosen value of switching frequency f to ensure that the converter is conducted in CCM. Boundary value of the inductance is given by

d3

The capacitance C is selected to reduce the output voltage ripple of the converter. Cbo is the limiting capacitance value required for a specified duty cycle α and chosen value of switching frequency f to reduce the output ripple voltage of the converter to a desired value and boundary value of the capacitance is given by

d4

where Vimax, αmin and αmax are minimum input voltage, minimum and maximum operating duty ratio respectively.

A 1000 W boost converter with an input voltage range 100-200 V and boosted output of 300 V is designed. For the design, the switching frequency 120 kHz, the output voltage ripple (ΔVO) of 1 %, and the output current ripple of 10 % of are considered.

Vi min = 100 V, Vi max = 200 V

Vo = 300 V, Po = 1000 W, Io = 3.33 A , fs = 120 kHz

Dmax = 0.67, Dmin = 0.33, IL = 1.20 A, Vo = 3 V

The calculated minimum value of inductor and capacitor are 0.46 mH and 7.41 µF, respectively. The nearby selected values of inductor and capacitor are 0.5 mH and 470 µF, respectively.

The pictorial view and details of terminal are shown in next chapter.

Chapter 2 Pictorial View

The pictorial view and front panel sticker of the module are as shown in following figures:
d5

d6

2.1 Connection Details
The different sections of the module are explained below:

i. Control Supply
Connect 230 V, 50 Hz single phase AC source to the kit by plugging power cord of the unit. This will provide control supply to the unit.

ii. Input and Output Terminals
d7
User can connect input DC voltage in the range of DC 100-200 V at this input terminal.

d8
User can connect load at this output terminal. The boosted voltage is in the range of 200-350 V.

iii. Gate pulses
User can select gate pulse for duty ratio control using this section.
d9

In “INTERNAL” mode (Int.) gate pulses are generated internally using PWM IC UC 3842. User can change the duty ration using POT given

In “EXTERNAL” mode (Ext.) 0-5 V gate pulses generated by the external controller can be interface. It will be connected at the input of driver section and after passing through driver it will reach to gate terminal.

NOTE:

• Connect active high 120 kHz gate pulses as per the design of converter.

• In external mode check gate pulses before giving DC supply. Make sure that gate pulses will not short DC source.

iv. Driver Circuit Status
d10

Driver status indications for Fault and Ready signals are provided. Feed power to power circuit only if driver status is healthy.

On fault with inverter, Fault LED becomes on and gate pulses are blocked. Use Reset switch for resetting driver card after clearing the fault.

If Fault occurred, then after solving Fault stop Gate pulses first and then press Reset.

NOTE: On Fault, Remove Gate pulses first then press RESET.

2.2 Part Number of Different Components Used

  1. CREE Silicon Carbide Power MOSFET - C3M0120090D

  2. FAIRCHILD Hyperfast Diode - RHRP30120

  3. FAIRCHILD PWM Controller UC3842

  4. Infineon Driver IC 1ED020I12-F2