ixys digital power mcu-controlled 3 kw two-phase ac · pdf fileixys digital power...

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IXYS Digital Power

MCU-Controlled 3 kW Two-Phase AC-DC Converter with Power Factor

Correction

Design File

IXRD1005-0717

Anatoliy Tsyrganovich, Leonid Neyman, Abdus Sattar

Contents

Design Summary .......................................................................................................................................... 1

Overview ...................................................................................................................................................... 3

Features ........................................................................................................................................................ 4

Potential Applications .................................................................................................................................. 4

Principles of Operation ................................................................................................................................ 5

Hardware Implementation ........................................................................................................................... 9

Efficiency of MCU-controlled PFC ........................................................................................................... 10

Summary .................................................................................................................................................... 10

Appendix A. Schematic Diagrams ............................................................................................................. 11

Appendix C. Bill of Materials .................................................................................................................... 14

Design Summary

Title MCU-Controlled 3 kW Two-Phase AC-DC Converter with Power Factor Correction

Specifications (i) Conversion power, maximum: 3 kW @ 240V power line

(ii) Input Voltage: 240 V AC 50/60 Hz

(iii) Output Voltage: 650 V ± 5%, programmable

(iv) Output Current: 2 A @ 650V

(v) Output Voltage Ripples: <5% at full load

Date July 09, 2017

Version 1.0

http://www.ixys.com/

MCU-Controlled 3 kW Two-Phase AC-DC Converter with Power Factor Correction

Design File

© 2017 IXYS 1 IXRD100501-0717

Overview

This design document extends IXYS’ Digital Power Control technology to High Power in the area of

Power Factor Correction (PFC) while enhancing fast switching capabilities and increasing load current

and voltage. This design also incorporates principles of Digital Inrush Current Control (IXRD1003) and

High Power Two-Phase Digital Power Factor Correction (IXRD1004). Functional control is based on

Zilog’s 8-bit Z8F6481 MCU.

This design, incorporating a 3 kW and over AC-DC converter with active PFC and two-phase interleaved

conversion, is aimed at solving specific issues arising at high power, including the following:

Decrease high current ripples at PFC switching frequency in the input power line

Provide efficient conversion in a wide load range

Decrease high frequency Electromagnetic Interference (EMI) caused by PFC switching devices

operating at high current and voltage

Decrease EMI caused by oscillations in inductor during discontinuous mode at low load that are a

result of transforming energy stored in stray capacitance/inductance

Design low loss high frequency 30A current capable inductor to store and efficiently pump

energy into output bulk capacitor

Develop a robust current balancing technology for polyphase PFC topology to reduce current

ripples in the input power line

Develop current sensing to sense high current of switching devices under conditions of high

common mode interference due to voltage drop on a PC board connections

Create overload and overvoltage protections to have reliable performance in unexpected

situations on customer side

Input AC power line current ripples are reduced in this design by using two-phase interleaved conversion

with pulse density modulation at low power. After power drops below 50% of maximum rated power, the

second phase is disabled to reduce switching losses, while the microcontroller adjusts appropriate

parameters to continue an uninterrupted conversion.

The quasi-resonant mode is used to reduce EMI during high power conversion, while the device operates

in discontinuous mode with an active snubber at lower power. The conversion frequency is up to 100 kHz

range, which allows for reduced size of the component. Inductor current switching time is in the range of

15–20 ns, depending on the current value, which is in the range of 6–30 A at 240 V AC input power line

voltage.

The inductor is designed and built by MPS Industries for high efficiency at a high switching frequency.

Two-phase interleaving architecture requires thorough current balancing to avoid high frequency

modulation in the AC input power line current. To achieve this, the MCU controls the position of the

peak current for each phase and centers the secondary phase peak between primary (master) phase peaks.


© 2017 IXYS 4 IXRD100501-0717

The MCU-based digital control also enables optimization of the converter’s overall performance,

including inrush current limiting, programmable overload protection schemes, and high power factor of

conversion, which makes this device competitive for use in high power applications.

Features

The MCU-controlled Power Factor Corrector reference design offers the following features:

Conversion power, maximum: 3 kW @ 240V power line

Input Voltage: 240 V AC 50/60 Hz

Output Voltage: 650 V ± 5%, programmable

Output Current: 2 A @ 650V

Output Voltage Ripples : <5% at full load

Input Current Ripples: <8%

Load Variation Range: >8x

Device Conversion Frequency: 80–100 kHz at high power

Programmable Overload, Overvoltage, and Brownout Protection

Digital Inruch Current Control

Soft Start

Power Good Status

Potential Applications

This reference design provides a basis for developing a variety of power management applications using

AC–DC converters with IXYS power devices and an MCU, including the following applications:

EV charging

Battery charging

Air conditioning systems

High power LED lighting

Welding equipment


© 2017 IXYS 5 IXRD100501-0717

Principles of Operation

The design approach for high power two-phase PFC considered the following parameters:

Peak inductor current modulation was chosen over other PFC topologies aiming at high power

conversion.

Quasi-resonant mode is used as a version of critical conduction mode, allowing the inductor

voltage to drop to its lowest value in the resonant process with strain capacitance after the

inductor is discharged into a load

Second conversion phase is set as slave with respect to first master phase

Balance of second phase current with respect to master phase is performed with HW and SW

Current sensing is improved to provide accurate current value to be used for detection of peak

current and measuring the actual load current value

Low power consumption (less than half of peak power) forces the second phase into sleep mode.

Pulse density modulation is used in addition to amplitude modulation to maintain the efficiency

of conversion.

Active snubber is used to reduce stray oscillation after the inductor is discharged into a load

Look-Up-Table (LUT) is used to simplify calculations performed by the 8-bit MCU

Prediction control is performed with LUT assistance; prediction is set to about 90% of expected

output parameters

Digital feedback is used to keep output parameters within the predetermined range.

Peak inductor current modulation allows the average line current to copy a form of the AC line input

voltage, which is used as a reference. In this design, DAC is used to provide reference voltage for peak

current modulation. Rectified and scaled input sine wave is applied to analog DAC input; while digital

DAC input is used to control the amplitude of DAC output in accordance with prediction and feedback

control.


© 2017 IXYS 6 IXRD100501-0717

Legend:

Blue and Magenta – first and second inductor voltages

Green and Yellow – first and second inductor charging currents

Figure 1. General Waveforms of Two-phase MCU-controlled PFC Converter

Note: Peak inductor current amplitude is 30 A at AC input of 240 V, Voltage on inductor is 650 V. The

snapshot of the bottom of the scope is a zoom of the top portion of the area between two white lines.

Switching operations are disabled near the zero crossing area of the AC input voltage to improve

efficiency by avoiding switching at low input voltages, when voltage cannot be busted to the required

output level.

MCU maintains Quasi-resonant mode by tracking the point of the inductor’s discharge and providing

necessary delay before turning the inductor’s current on again. Delay value may have some variance

because the inductor voltage has a dull bottom plateau.

Second conversion phase is synchronized with the master phase. Synchronization is implemented

through a delay of the beginning of the second phase conversion cycle with respect to the first phase

timing.

Balance of second phase current is used for ripples reduction in the input power line.

Current sensing is based on true differential sensing to compensate the high common mode interference

caused by high currents on the PC board.

Low power consumption state is detected by measuring the load current while output voltage VOUT is

maintained in the specified range. Load current is measured during AC input voltage zero crossing, where


© 2017 IXYS 7 IXRD100501-0717

conversion is halted, allowing for better accuracy. Voltage drop on the current sensing resistor is

amplified with inversion into positive voltage domain. If the load current drops below half of the

maximum rated value, the second phase conversion is halted.

Pulse density modulation is used to further reduce generated power, if power consumption falls farther

than half of rated power.

Active snubber is activated at low power consumption during the time frame from inductor discharge to

the start of the next conversion cycle. The snubber timing is generated by the MCU. An illustration of

active snubber performance is shown in Figure 2

(a) (b) Legend:

Legend: Magenta – first inductor voltages; Green – first inductor charging current;

Yellow – snubber control signal; Blue – power line current.

Figure 2. Inductor Voltage with Snubber Active (a) and Snubber Disabled (b)

Look-Up-Table (LUT) simplifies MCU operations to speed up the algorithm. The data for LUT is

converted to 8-bit representation. The main LUT data contain load impedance, which is estimated based

on measuring output VOUT and load current iLoad. Load impedance is more informative, because it is

estimated not only in steady state, but in transition modes as well when VOUT is not settled yet. Therefore,

judging on load power consumption is more accurate, if done on the load impedance. The load impedance

is calculated as R_Load for simplicity of MCU operation. The equation, R_Load = f(iLoad, VOUT) is

represented in Figure 3. The axis values are scaled to 8-bit representation.

The LUT base algorithm is also used in prediction control.


© 2017 IXYS 8 IXRD100501-0717

Note: Horizontal axis is iLoad

Figure 3. Two-dimensional representation of R_Load as Laid Out in LUT

Prediction control sets the initial values for the peak value of the inductor current. The DAC data

supplied to DAC digital input and for delay of the next conversion pulse is denoted as Delay to modulate

pulse density.


© 2017 IXYS 9 IXRD100501-0717

Hardware Implementation

This MCU-controlled PFC, which consists of an MCU Module, a Main Power Board, and an Auxiliary

Board, is shown in Figure 4. The detailed circuit schematics are included in Appendix A. The MCU and

Auxiliary Modules are implemented as add-on devices powered by an auxiliary power supply. The MCU

module contains a connector for MCU programming. The MCU should be programmed before powering

the entire system.

The Main Power Board is a four-layer surface-mount board that provides easy access to test points. Diode

Bridge D5 (see Appendix A, Figure 5), switching MOSFETs Q4, Q6, MOSFETs Q1, Q3 used as boost

diodes, and MOSFET Q5 used as an Inrush Current Control Switch are mounted on heat sinks. Power

dissipated on MOSFETs is less than 54 W at 3000 W output power. This board may be powered from a

50 Hz or 60 Hz 220/240V AC source. The connector J4 is used to provide auxiliary power supply ±3.3V

for the MCU and ±12V for the gate drivers on the Main Power Board.

Figure 4. Main Power Board with MCU and Auxiliary Modules


© 2017 IXYS 10 IXRD100501-0717

Efficiency of MCU-controlled PFC

The efficiency of the reference design schematic is determined for the conversion circuitry, only

excluding the diode rectifier and the AC filter. At a load power of 3000 W, the power loss is 54 W, which

corresponds to an efficiency of 98.2%. Additional power loss is attributed to the Diode Bridge and AC

line filter inductors.

Summary

This MCU-controlled PFC is a continuation of digital power control designs based on Zilog’s F6481

series of MCUs, which offer flexibility in implementing a unique control algorithm that aids in efficient

power systems. This design achieves a high level of efficiency, increased stability, and reliable

performance across a wide range of input voltages and loads. Because of an innovative current

measurement algorithm, this Controller allows common input and load grounds. Users can optimize the

device for a wide range of input voltages and power consumption. This design provides instant over-

current protection, followed by an intervention by the MCU for corrective action.

The MCU-controlled PFC is designed for use at input power lines 220 V/240 V for a range of power

loads. Digital control can be used to build a user interface that would allow users to change device

parameters, gather statistics, add a communication interface, remotely monitor performance, or change

parameters.


© 2017 IXYS 11 IXRD100501-0717

Appendix A. Schematic Diagrams

The schematic diagrams of the MCU-controlled PFC design are shown in Figures 5 through 7.

Figure 5. Schematic Diagram of MCU-controlled PFC Main Board


© 2017 IXYS 12 IXRD100501-0717

Figure 6. Schematic Diagram of Digital Control Module

Figure 7. Schematic Diagram of Auxiliary Board


© 2017 IXYS 13 IXRD100501-0717

Appendix B. Board of Components

Figure 8. Main Board Layout (Top, Mid, and Bottom Layers)

Figure 9. Layout of Digital Control Module (Top and Bottom Layers)

Figure 10. Layout of Auxiliary Module (Top and Bottom Layers)


© 2017 IXYS 14 IXRD100501-0717

Appendix C. Bill of Materials

Table 1.Bill of Materials for Main Board

Count Reference Designator Value Description Manufacturer 1 BR1 BAS 3007A BAS 3007A-RPP E6327 Infineon Technologies

1 C1 470 pF GRM31BR73A471KW01L Murata

2 C10, C13 100 pF CL31C101JIFNFNE Samsung

2 C12, C19 0.33 uF C1608X7R1E334K080AC TDK Corporation

2 C14, C41 100 uF 860080473006 Wurth Electronics Inc

2 C15, C16 6800 pF C967U682MYVDBA7317 Kemet

2 C17, C24 0.47 uF B32653A6474K EPCOS Inc

4 C2, C3, C4, C5 50 uF 1778410M3DB40 Vishay

1 C20 1.5 uF ECW-FA2J155J Panasonic Electronic

Components

6 C21, C22, C23, C25, C28, C29 1 uF C1608X7R1E105K080AB TDK Corporation

1 C26 0.033 uF C1608X7R1E333K080AC TDK Corporation

1 C27 33 pF CL31C330JHFNFNE Samsung

1 C30 4.7 uF GRM31CR71E475KA88L Murata

4 C31, C32, C33, C34 0.1 uF CL10B104KA8NNNC Samsung

2 C35, C36 10 uF CL31B106KAHNNNE Samsung

1 C37 10 uF CL10A106MA8NRNC Samsung

2 C38, C39 10 uF CL10A106MQ8NNNC Samsung

1 C40 1.5 uF R82CC4470AA30J Kemet

4 C42, C43, C44, C45 0.01 uF GRM188R71H103KA01D Murata

4 C6, C7, C11, C18 6800 pF CC1206KKX7RZBB682 Yageo

1 C8 0.47 uF ME104K2J150B050S RFE International

1 C9 0.15 uF C1812C154KBRACTU Kemet

4 D1, D4, D8, D9 MURA160T3G MURA160T3G ON Semiconductor

1 D10 BAT54CW BAT54CW_115 NXP Semiconductors

1 D11 BAT54AW BAT54AW_115 NXP Semiconductors

1 D2 RS3MB-13-F RS3MB-13-F Diodes Incorporated

2 D3, D5 DSP45-12A DSP45-12A IXYS Corporation

2 D6, D7 ES2AA-13-F ES2AA-13-F Diodes Incorporated

2 J1, J2 1714971 Phoenix Contact

2 J3, J6 5-5530843-0 TE Connectivity

1 J4 8624-10-89-2061 Molex

1 J5 BBL-102-GE Samtec

2 L1, L2 160 uH HWIF6762-030A-151S MPS

2 Q1, Q3 IXFH30N85X IXFH30N85X IXYS Corp.

1 Q2 AOD2N60 AOD2N60 Alpha & Omega

Semiconductor Inc.

3 Q4, Q5, Q6 IXFH50N85X IXfH50N85X IXYS Corp.

3 Q7, Q9, Q10 BSS84W-7-F DMP2123L Diodes Inc.

1 Q8 DMN601WK-7 DMN601WK-7 Diodes Inc.

9 R1, R2, R3, R13, R15, R25,R26,

R28, R29

332 k RMCF1206FT332K Stackpole Electronics Inc

2 R10, R20 0.5 CRM0805-FX-R510ELF Bourns Inc.

3 R12, R14, R22 22 LTR50UZPF22R0 Rohm Semiconductor

1 R18 1 RMCF0603FT1R00 Stackpole Electronics Inc

2 R23, R24 49.9 k RMCF1206FT49K9 Stackpole Electronics Inc

4 R30, R37, R38, R56 10 k RMCF0603FT10K0 Stackpole

4 R32, R33, R34, R43, 143 k RMCF1206FT143K Stackpole Electronics Inc

4 R35, R41, R42, R57 1 k RMCF0603FT1K00 Stackpole Electronics Inc

1 R39 100 k RMCF0603FT100K Stackpole Electronics Inc

1 R4 33 RMCF0603FT33R0 Stackpole Electronics Inc

1 R40 3.01 k RMCF0603FT3K01 Stackpole Electronics Inc


© 2017 IXYS 15 IXRD100501-0717

4 R44, R45, R46, R49 0.01 LRF3WLF-01-R010F TT Electronics/IRC

2 R47, R48 0.04 LRF3WLF-01-R040F TT Electronics/IRC

2 R5, R6 1 k CRM2512-JW-102ELF Bourns Inc.

1 R50 402 RMCF0603FT402R Stackpole Electronics Inc

4 R51, R52, R53, R54 49.9 RMCF0603FT49R9 Stackpole Electronics Inc


6 R7, R11, R17, R21, R27, R36, 20 k RMCF0603FT20K0 Stackpole Electronics Inc

2 R8, R19 4.99 RMCF0805FT4R99 Stackpole Electronics Inc

2 R9, R16 3.01 RMCF0805FT3R01 Stackpole Electronics Inc

1 T1 FS20-120-C2 FS20-120-C2 Triad Magnetics

1 TR1 4.5 mH 7448051804 Wurth Electronics Inc

1 TR2 BV020-5480.0 BV020-5480.0 Pulse

2 U1, U2 IXDD630YI IXYS Corp.

1 U3 IX2120B IXYS Corp.

2 U4, U5 EL5170 EL5170IYZ-T7 Intersil

1 U6 XC6216C202 XC6216C202PR-G Torex

1 U7 XC6902331 XC6902331PR-G Torex

Table 2. Bill of Materials for MCU Board

Count Reference Designator Value Description Manufacturer 1 C1 330 pF GRM1885C1H561JA01D Murata

1 C12 0.033 uF C0603C333K4RACTU Kemet

2 C13, C18 8 pF GRM1555C1H8R0DA01D Murata

1 C15 33 pF CL10C330KB8NNNC Samsung

2 C2, C4 1000 pF GRM188R71H102KA01D Murata

2 C20, C21 0.039 uF GRM188R71H393KA61D Murata

3 C3, C22, C23 0.01 uF GRM188R71H103KA01D Murata

7 C5, C7, C9, C11, C16, C17, C19 0.1 uF CL10B104KA8NNNC Samsung

2 C6, C14 1 uF TMK107B7105KA-T Taiyo Yuden

2 C8, C10 4.7 uF GRM188R61E475KE11D Murata

4 D7, D10, D11, D12 BAT42XV2 BAT42XV2 Diodes Inc.

2 J4, J5 DEBUG Header 67996-406HLF FCI

1 J6 Board layout



4 R11, R12, R13, R14 10 k RMCF0603FT10K0 Stackpole Electronics Inc



1 R18 0 HCJ0603ZT0R00 Stackpole Electronics Inc


1 R2 11 k RMCF0603FT11K0 Stackpole Electronics Inc





3 R3. R4, R5 6.49 k RMCF0603FT6K49 Stackpole Electronics Inc

2 R31, R32 806 RMCF0603FT806R Stackpole Electronics Inc

2 R6, R15 1 M RMCF0603FT1M00 Stackpole Electronics Inc



2 U1, U2 Z8F6481AR024XK Zilog

2 U10, U11 MAX9140EXK-T Maxim

1 U3 416F24022IKR 416F24022IKR TS-Frequency Controls

1 U4 NC7SZ08P5X Fairchild Semic.

2 U6, U7 NC7SZ74K8X Fairchild Semic.


© 2017 IXYS 16 IXRD100501-0717

Table 3. Bill of Materials for Auxiliary Board

Count Reference Designator Value Description Manufacturer 5 C1, C2, C3, C4, C8 0.1 uF CL10B104KA8NNNC Samsung

1 C5 1 uF TMK107B7105KA-T Taiyo Yuden

1 C6 6.8 pF CL10C6R8DB8NNNC Samsung

1 C9 560 pF GRM1885C1H561JA01D Murata

1 C7 5600 pF CL10B183JB8NNNC Samsung

1 J1 Board Layout

2 U1, U2 LMV116MF/NOPB Texas Instr.

1 U3 MAX9140EXK-T Maxim

1 U7 NC7SZ08P5X Fairchild Semic.

3 U4, U5, U6 NC7SZ74K8X Fairchild Semic.

2 R15, R16 0 HCJ0603ZT0R00 Stackpole Electronics Inc

3 R11, R13, R14 1 k RMCF0603FT1K00 Stackpole Electronics Inc



2 R1, R2 10 k RMCF0603FT10K0 Stackpole Electronics Inc



4 R3, R4, R5, R6 49.9 RMCF0603FT49R9 Stackpole Electronics Inc


1 D1 SD103ASDM-7-F Diodes Incorporated


© 2017 IXYS 17 IXRD100501-0717

Warranty and Use

IXYS CORP. MAKES NO WARRANTY, REPRESENTATION OR GUARANTEE, EXPRESS OR

IMPLIED, REGARDING THE SUITABILITY OF ITS PRODUCTS FOR ANY PARTICULAR

PURPOSE, NOR THAT THE USE OF ITS PRODUCTS WILL NOT INFRINGE ITS INTELLECTUAL

PROPERTY RIGHTS OR THE RIGHTS OF THIRD PARTIES WITH RESPECT TO ANY

PARTICULAR USE OR APPLICATION AND SPECIFICALLY DISCLAIMS ANY AND ALL

LIABILITY ARISING OUT OF ANY SUCH USE OR APPLICATION, INCLUDING BUT NOT

LIMITED TO, CONSEQUENTIAL OR INCIDENTAL DAMAGES.

IXYS Corp. products are not designed, intended, or authorized for use as components in systems intended

for surgical implant into the body, or other applications intended to support or sustain life, or for any

other application in which the failure of the IXYS Corp. product could create a situation where personal

injury or death may occur.

IXYS Corp. reserves the right to make changes to or discontinue any product or service described herein

without notice. Products with data sheets labeled "Advance Information" or "Preliminary" and other

products described herein may not be in production or offered for sale.

IXYS Corp. advises customers to obtain the current version of the relevant product information before

placing orders. Circuit diagrams illustrate typical semiconductor applications and may not be complete.

IXYS Corp.

1590 Buckeye Dr.

Milpitas, CA 95035-7418

Phone: 408. 457.9000

Fax: 408. 496.0222

http://www.ixys.com

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