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Power Factor Correction – Why and How? Renesas Electronics America Inc. © 2012 Renesas Electronics America Inc. All rights reserved. Renesas Technology & Solution Portfolio 2 © 2012 Renesas Electronics America Inc. All rights reserved. Microcontroller and Microprocessor Line-up 2010 2013 1200 DMIPS, Superscalar 32-bit Automotive & Industrial, 65nm 600µA/MHz, 1.5µA standby 1200 DMIPS, Performance Automotive, 40nm 500µA/MHz, 35µA deep standby 500 DMIPS, Low Power Automotive & Industrial, 90nm 600µA/MHz, 1.5µA standby 165 DMIPS, FPU, DSC Industrial, 40nm 242µA/MHz, 0.2µA standby 165 DMIPS, FPU, DSC Industrial, 90nm 242µA/MHz, 0.2µA standby 8/16-bit 25 DMIPS, Low Power Industrial, 90nm 1mA/MHz, 100µA standby Industrial & Automotive, 150nm 190µA/MHz, 0.3µA standby 44 DMIPS, True Low Power 10 DMIPS, Capacitive Touch Industrial & Automotive, 130nm 144µA/MHz, 0.2µA standby Industrial Automotive, 130nm Wide Format&LCDs 350µA/MHz, 1µA standby 3 Embedded Security, ASSP © 2012 Renesas Electronics America Inc. All rights reserved. Enabling the Smart Society Energy efficiency is key to a Smart Society Energy harvesting Home Automation Smart Metering Industrial Motors Power quality is key to efficient energy management 4 © 2012 Renesas Electronics America Inc. All rights reserved. Agenda Market drivers for Power Factor Correction What is Power Factor and why do we need to correct it? Definition of Power Factor (PF) What causes PF degradation Impacts of bad PF on power distribution and billings How do we correct bad Power Factor? Basic PFC topologies Renesas PFC Solutions Analog and Digital Solutions Implementation with Renesas MCU and Analog & Power devices Summary 5 © 2012 Renesas Electronics America Inc. All rights reserved. PFC Market Drivers 6 © 2012 Renesas Electronics America Inc. All rights reserved. What Drives the PFC Market? Some energy is delivered but not used due to bad PF Consumers Some consumers are charged for energy they don’t use Power utilities Need to cover consumers who are not charged for bad PF Need to compensate by over-sizing: – Distribution lines, Transformers, Energy production Harmonics can disrupt other consumers Government regulations 7 © 2012 Renesas Electronics America Inc. All rights reserved. What is Power Factor? Ammeter Wattmeter A A A P 5.1 A 120V 60Hz AC Motor ~ Real Power: P = 400 W (Watts) Apparent Power: S = 120V x 5.1A = 612 VA (Volt Ampere) Power Factor: PF = 400/612 = 0.653 8 400W © 2012 Renesas Electronics America Inc. All rights reserved. P (W ) PF S (VA) What is Power Factor? Where did the power go? P (W) AC voltage Inductive Load φ AC current S’ φ S (VA) Displacement P(W ) DPF S (VA) Range: 0 – 1 Q(VAR): Reactive Power DPF = 1 when Q = 0 9 © 2012 Renesas Electronics America Inc. All rights reserved. DPF cos Q (VAR) What is Power Factor? Total Harmonic Distortion (THD) Non-linear loads distort original AC current AC current Distortion AC voltage φ Displacement 39 THD I 3 I1 2 n I1: RMS value of AC current fundamental In: RMS value of AC current nth harmonic Total Power Factor Combination of Displacement Power Factor (DPF) and Distortion Power Factor (THD) 10 © 2012 Renesas Electronics America Inc. All rights reserved. TPF DPF 1 1 THD 2 What causes PF degradation? Inductive loads store reactive power and cause current lag Non-linear loads with switching elements distort the original AC current and introduce harmonics Total Power Factor 1 TPF DPF 1 THD 2 Bad PF: TPF 1 11 © 2012 Renesas Electronics America Inc. All rights reserved. Question 1 What causes PF degradation? A. Resistive loads B. Inductive loads C. Capacitive loads D. Non-linear loads E. B, C, D F. None of the above 12 © 2012 Renesas Electronics America Inc. All rights reserved. Why Power Factor < 1 is bad? Reactive energy is not used to produce real power Utilities need to compensate by over sizing: Distribution lines Transformers Energy production Harmonic distortion can disrupt other consumers 13 © 2012 Renesas Electronics America Inc. All rights reserved. Power Factor Correction 14 © 2012 Renesas Electronics America Inc. All rights reserved. Power Factor Correction AC current AC voltage φ Displacement PFC makes the load look like a resistor! Need to control current to match the shape and phase of the voltage AC voltage 15 © 2012 Renesas Electronics America Inc. All rights reserved. AC current Power Factor Correction Methodologies Passive PFC Passive components to compensate for reactive energy loss Active PFC Active components to drive solid state switches with PWM signals in combination with passive reactive components such as inductors + - 16 © 2012 Renesas Electronics America Inc. All rights reserved. Passive Power Factor Correction Passive PFC Control harmonic current using filter Expensive large high-current inductor No automatic adjustment for wider AC input power DC output varies with AC input voltage 17 © 2012 Renesas Electronics America Inc. All rights reserved. Active Power Factor Correction Active PFC Input current is controlled to follow the shape and phase of input AC voltage Q Transistor Q is switched ON/OFF at a PWM rate Most common configuration – Boost converter Efficiency is affected by Q switching losses and diode recovery 18 © 2012 Renesas Electronics America Inc. All rights reserved. Active PFC Topologies Critical Conduction Mode (CRM) Rectified, unfiltered AC voltage Inductor ripple current Average AC current Q Q switched on when inductor current reaches zero Inductor ripple current - High Low power applications No recovery loss through diode 19 © 2012 Renesas Electronics America Inc. All rights reserved. Active PFC Topologies Continuous Conduction Mode (CCM) Rectified, unfiltered AC voltage Inductor ripple current Average AC current Q Q switched on before the inductor current reaches zero Inductor ripple current – Low High power applications Recovery loss through the diode 20 © 2012 Renesas Electronics America Inc. All rights reserved. Implementation Example of Active CRM PFC PFC Boost Converter DC BUS Rectified, unfiltered AC voltage Average AC current Critical Conduction Mode Timer CMP+ A/D Interlock Internal Vref 21 (CRM) ANI0 Zero current detection TMX00 T1 TMX00 (PFC output) PFC-ON pulse width MCU © 2012 Renesas Electronics America Inc. All rights reserved. PFC-off pulse width CMP+ (Zero current detection) Active PFC Topologies Single channel 120V AC D1 ~ Q1 L1 Q1 C IL1 PFC Cb Two channel interleaved D2 Q1 L2 120V AC Q2 D1 ~ IL1 L1 Q1 C PFC Q2 Cb IL2 IL1+IL2 Reduced current ripple 22 © 2012 Renesas Electronics America Inc. All rights reserved. Effect of High-frequency Switching Harmonics and inductor current ripple can disrupt other consumers Regulation standards apply – IEC61000-2-2 L 120V AC ~ C C L Q Higher ripple current will require better filters with multiple stages 23 © 2012 Renesas Electronics America Inc. All rights reserved. Advantages of Interleaving Reduced current ripple Size and number of input filters can be reduced Size of inductors, capacitor, switching devices can be reduced Overall efficiency is increased 24 © 2012 Renesas Electronics America Inc. All rights reserved. Interleaved PFC Versus Single Channel Single channel Inductor ripple current affects size of: – Inductor, Bulk Capacitor and input EMI filter High current through IGBT/MOSFET cause conduction losses Two channel interleaved Two sets of smaller and less expensive components: – Inductor, Diode, Capacitor and IGBT/MOSFET 180° out of phase switching – Inductor ripple currents cancel out each other – Further reduction in bulk capacitor size and EMI filter Better efficiency due to reduced conduction losses Multiple interleaving can further reduce the size of components 25 © 2012 Renesas Electronics America Inc. All rights reserved. Interleaved PFC versus Single Channel CCM topology for large power application (>300W) 26 Item Single Channel 2-Ch Interleaved Ripple current Large Small Inductor 1 large 2 small (less $) Transistor 1 large 2 small (less $) Diode 1 large (SiC?) 2 small (less $) Bulk capacitor Large Small EMI filter Large Small Efficiency Good Better © 2012 Renesas Electronics America Inc. All rights reserved. Typical Application - Motor Control and PFC L D Fast Recovery Diode ( SiC) 3 Phase Inverter stage C 3 Phase Motor 90 – 264 VAC T AC voltage, DC voltage current PWM PFC Control IC 27 © 2012 Renesas Electronics America Inc. All rights reserved. Current, voltage, temperature, OC-detection MCU PWM Gate Driver PWM Speed, Position Digital PFC for Motor Control Inverter L D Fast Recovery Diode ( SiC) 3 Phase Inverter stage C 3 Phase Motor 90 – 264 VAC T AC voltage, DC voltage current Current, voltage, temperature, OC-detection PWM MCU 28 © 2012 Renesas Electronics America Inc. All rights reserved. PWM Gate Driver PWM Speed, Position Renesas PFC Solutions Renesas offers a variety of analog and digital devices to support PFC Analog: PFC Controller ICs Single channel and interleaved CCM and CRM topologies Internal MOSFET/IGBT driver Digital: MCUs with integrated peripherals High performance CPU with FPU and 10ns flash access Internal PGAs and Comparators High-speed ADC with multiple S&H Fast over-current protection by hardware Fast interrupt response 29 © 2012 Renesas Electronics America Inc. All rights reserved. Analog PFC Solutions 30 © 2012 Renesas Electronics America Inc. All rights reserved. Renesas Offers Complete Analog PFC Solutions PFC Controllers – CCM (Continuous Conduction Mode) – CRM (Critical Conduction Mode) PFC Boost Switch – Super Junction MOSFETs for high frequency (> 50 kHz), up to 2.5 kW – High Speed, Low Vceon, IGBTs for lower frequency (< 40 kHz) and above 2.5 kW PFC Boost Diode (SiC) Support and Collateral Datasheet Evaluation Boards Technical Support 31 © 2012 Renesas Electronics America Inc. All rights reserved. Renesas Analog PFC Controller Solutions CCM CRM 32 Mode Part # Features Interleaved R2A20114 R2A20104 Small current ripple Server Average SW noise Air conditioner More complex circuit Induction heating Single R2A20115 Large current ripple Large SW noise Simple circuit Interleaved R2A20132 R2A20118A R2A20117 R2A20112 Small current ripple Air conditioner Average SW noise Plasma TV More complex circuit PC Office automation Single R2A20113 Large current ripple Large SW noise Simple circuit © 2012 Renesas Electronics America Inc. All rights reserved. Applications Plasma TV PC Office automation LCD monitor AC adaptor LCD projector CCM Interleaved PFC Controllers 2A20114/20104 Phase drop control input Internal / external clock can be used 20104 can use current transformer Current transformers 33 © 2012 Renesas Electronics America Inc. All rights reserved. CRM Interleaved PFC Controllers 2A20132 Phase drop control input OTC – prevents increase of switching frequency at light loads — Increased efficiency at light loads Protection circuits: Brownout, ZCD pin opening 34 © 2012 Renesas Electronics America Inc. All rights reserved. CCM Interleaved PFC Controllers R2A20118/117/112 Protection features ZCD open/short OCP timer latch RAMP charge current Brownout Soft start Gate drivability VFB 1.5% 35 © 2012 Renesas Electronics America Inc. All rights reserved. Digital PFC Solutions 36 © 2012 Renesas Electronics America Inc. All rights reserved. PFC Control Functions 85 – 264VAC PF > 0.9 400V DC PFC Hardware Gate PWM Inductor ripple current VAC VREF 37 © 2012 Renesas Electronics America Inc. All rights reserved. OC/OV Detection VDC PFC Controller PFC Control Functions – Input/Output Control function Input Output Output voltage Feedback voltage Constant DC bus voltage AC voltage range AC voltage Adjust to 85-264VAC IGBT current Inductor current AC voltage Over-current Hardware protection Over-voltage Under-voltage 38 © 2012 Renesas Electronics America Inc. All rights reserved. Inductor current amplitude Synchronize with AC voltage phase Disable IGBT gate signals Digital PFC for Motor Control Inverter L D Fast Recovery Diode ( SiC) 3 Phase Inverter stage C 3 Phase Motor 90 – 264 VAC T AC voltage, DC voltage current PWM Rx62T MCU 39 © 2012 Renesas Electronics America Inc. All rights reserved. Current, voltage, temperature, OC-detection PWM Gate Driver PWM Speed, Position Interleaved PFC Reference Design Auxiliary power DC/DC converter 395V 3.8A output 85-264 VAC input Rx62T MCU board 40 © 2012 Renesas Electronics America Inc. All rights reserved. PFC CH1 PFC CH2 SIC Diodes Complete PFC Solution from Renesas Diode: RJS6005TDPP-EJ (target) IGBT: RJH60F4DPK IGBT: RJH60F4DPK RX62T/100pin R5F562TAADFP 41 © 2012 Renesas Electronics America Inc. All rights reserved. System Specification 1 MCU R5F562TAADFP (RX62T) (Flash: 256kB, RAM: 32kB, CLK: 100MHz, VCC: 5V ) 2 Circuit system Continuous Conduction Mode / 2-phase interleaved 3 Switching device 4 Input voltage AC 85 to 264 V 5 Output voltage DC 395 V 6 Maximum output current 3.8 A 7 Maximum output power 1.5 kW 8 PWM frequency 9 Efficiency 10 Power factor 42 IGBT (RJH60F4DPK: 600V/50A) © 2012 Renesas Electronics America Inc. All rights reserved. 35 kHz / 1 phase x 2 > 96 % > 0.96 PFC Controller System Block Diagram PFC OUT 390V RX62T Multiplyer INPUT AC85~264V × Deviation Voltage Controller Deviation Current Controller Duty 1 Duty 2 Protection Controller ADC 10bit Gate Driver PWM Timer2 OUT2 Gate Driver CS1 ADC 12bit + VAC OUT1 OCP setting - Voltage Reference PWM Timer1 CS2 FB OVP Setting OSC Controller CLK:100MHz CLK:50MHz GND HW 43 © 2012 Renesas Electronics America Inc. All rights reserved. SW Protection Controller Implementation CS1 CC1 GD1 CS2 CC2 GD2 VAC VFB CS1,2 VAC VFB CC1,2 VC 44 VC - Current sensing Ch1,2 - AC Input voltage - DC Output voltage - Current controller 1,2 - Voltage controller © 2012 Renesas Electronics America Inc. All rights reserved. Control loops: Two-stage IIR filter Program Flow Main ADC conversion interrupt Main Conversion start by GPT Interrupt 10-Bit ADC VAC 12-Bit ADC CS FB ADC to voltage calculation Voltage reference calculation Voltage controller Voltage IIR filter controller Current controller Current IIR filter controller PWM update 45 Conversion complete interrupt © 2012 Renesas Electronics America Inc. All rights reserved. GPT PWM duty update RX62T MCU Resources Used Signal name 46 MCU Peripheral Pin Name I/O Resolution Functions GD1 GPT0 GTIOC0A-A OUT 20ns PWM for IGBT1 gate GD2 GPT1 GTIOC1A-A OUT 20ns PWM for IGBT1 gate VFB 12-Bit ADC0 AN000 IN 12bit Output DC voltage sensing CS2 12-Bit ADC0 AN001 IN 12bit IGBT1 current sensing CS2 12-Bit ADC0 AN002 IN 12bit IGBT2 current sensing VAC 10-Bit ADC AN2 IN 10bit Input AC voltage sensing © 2012 Renesas Electronics America Inc. All rights reserved. RX62T Peripherals used for PFC RX 62T 390VDC RX CPU (100 MHz) Flash up to 256KB FPU Data Flash 8KB (30k times E/W) Multiplier, Divider, Multiply, Accumulate ~ IL2 GPT 16-bit PWM Timer GPT0 Ch 6&7 3-ph PWM 16-bit PWM Timer GPT1 47 CS1 0.02Ω GD1 GD2 GD2 uPC844G2 16-bit PWM Timer GPT2 0.02Ω 16-bit PWM Timer GPT3 Ch 0 Hall / BEMF Input 16-Bit CMT 4 channel Multi purpose timer FB uPC844G2 Ch 3&4 3-ph PWM Ch 5 Dead-time compensation uPC844G2 RAM 16KB 16-Bit MTU3 Ch 1&2 2 Encoder Inputs IL1 12bit ADC 4-ch 3 PGA 3 Comp x2 x2 10bit ADC 12-ch © 2012 Renesas Electronics America Inc. All rights reserved. CS2 CS1 VFB VAC CS2 Gate Drive, Synchronized ADC sampling Average coil current 1 Duty set 1 IL1 uPC844G2 Timer count 1 VFB FB GD1 GD1 uPC844G2 IL2 CS1 CS1 0.02Ω 180deg phase shift IGBT current 2 Average coil current 2 GD2 GD2 Duty set 2 uPC844G2 Timer count 2 0.02Ω CS2 CS2 GD2 GD1 period GD2 period CS1 ADC sampling CS2 ADC sampling FB ADC sampling 48 © 2012 Renesas Electronics America Inc. All rights reserved. Tn Tn+1 Tn Tn+2 Tn+1 Tn+2 Overvoltage Protection by Hardware - Example of PFC and DC/DC converter PFC-OUT +5V 2MΩ 10k PFC-FB 3.33V 18.56kΩ OVP_PFC PWM-OUT 20kΩ 5.1kΩ 2kΩ PWM-FB OVP_PWM PFC-OUT 3.33V * 2 POE0# *1 PFC-GD1 MTIOC3B RX62T PFC-GD2 MTIOC4A PWM-GD MTIOC4B R5F562TAADFP * 1. Protection by external hardware * 2. Protection by internal hardware by POE function 49 © 2012 Renesas Electronics America Inc. All rights reserved. PWM-OUT Feedback Signal Measurement by 12-Bit ADC ADC unit 0 AN000/AN101 PGA S/H VCSPF1_IN AN001/AN101 PGA S/H VCSPF2_IN AN002/AN102 VAC_IN AN003/AN103 PGA S/H Data Register 0 Multiplexer VFBPF_IN Data Register 1 ADC Data Register 2 Data Register 3 Three S&H for sensing currents and voltage for interleaved PFC. PGA (Programmable Gain Amp) with selectable gain 1 usec conversion time per channel at AVCC0=AVCC=4.0 to 5.5V. 50 © 2012 Renesas Electronics America Inc. All rights reserved. Implementation with General Purpose Timers 4-Channels, 16-Bit counters, 100 MHz count clock Phase shifted operation – 180° for interleaved PFC Triangular wave with center aligned PWM ADC conversion start trigger by timer AD trigger CPU Interrupt GTIOC0A-A/B GPT0 GTIOC0B-A/B AD trigger CPU Interrupt GPT1 GTIOC1B-A/B GPT3 GTIOC3A ON OFF ON OFF GPT1.GTCNT GTCCRA1 GTIOC3B POE3 CPU interrupt for POE 51 OFF GTIOC2B-A/B Output protect CPU Interrupt GTIOC0A-A GTIOC2A-A/B GPT2 AD trigger GTCCRA0 GTIOC1A-A/B AD trigger CPU Interrupt GPT0.GTCNT © 2012 Renesas Electronics America Inc. All rights reserved. GTIOC1A-A ON OFF 1. GTPR0,1: 2. GTCCRA0,1: ON OFF PWM frequency(35kHz) PWM duty ON Example of PFC Control Trigger by GPT0 GPT0.GTCNT Counter value GTP0.GTPR PFC Cycle hhhh ffff eeee dddd cccc bbbb aaaa Time Register write GTP0.GTCCRC PFC Duty Cycle Register write ffff Register write dddd Buffer transfer at crest bbbb hhhh Buffer transfer at through ffff GTIOC0A output PFC gate drive GTADTRA ADC Trigger ADC conversion start PFC control start 52 ADC conversion end ADC conversion end interrupt ∆t © 2012 Renesas Electronics America Inc. All rights reserved. Register write PFC control end dddd Buffer transfer at crest hhhh CPU BW for Interleaved PFC: 32% @35KHz Control loop processing: 9us 4.5us PFC control timing 28us GD1 53 © 2012 Renesas Electronics America Inc. All rights reserved. (32%) 4.5us AC Current Waveforms @1.5KW – 100V AC input 1.5KW @ 100V AC Input Input AC voltage Input AC current Inductor current Output voltage ripple 54 © 2012 Renesas Electronics America Inc. All rights reserved. Rx62G High Resolution PWM Timer Each GPT channel can generate HR-PWM for two outputs independently Minimum resolution is 1/32 of normal resolution: 312.5psec @100MHz rising falling 390.0psec @80MHz GTDLYRA GTDLYFA GTDBU GTDVU GTPBR GTPR High resolution Controller GTCNT AD trigger Comparator CPU Interrupt GTADTRA GTADTRB GTCCRB GTCCRA GTADTBRA GTADTBRB GTCCRE GTCCRC GTCCRF GTCCRD GTADTDBRA GTADTDBRB CPU interrupts Output protect GTDBD GTDVD Output control Input control GTPDBR Comparator input GTTCRA GTTCRA External Trigger. GTIOCA PWM1 GTDLYRA GTDLYFA PWM2 POEx 15 Upper 16bit 4 Lower 5bit 0 0 + GTDLYRA GTTCRA + GTDLYFA 55 © 2012 Renesas Electronics America Inc. All rights reserved. Question 2 What PFC method is used in the Renesas digital reference design? A. Single-channel PFC in Critical Conduction Mode (CRM) B. Single-channel PFC in Continuous Conduction Mode (CCM) C. Dual-channel interleaved in Continuous Conduction Mode (CCM) D. None of the above 56 © 2012 Renesas Electronics America Inc. All rights reserved. Summary Market drivers for Power Factor Correction What is Power Factor and why do we need to correct it? Definition of Power Factor (PF) What causes PF degradation Impacts of bad PF on power distribution and billings How do we correct bad Power Factor? Basic PFC topologies Renesas PFC Solutions Analog and Digital Solutions Implementation with Renesas MCU and Analog & Power devices 57 © 2012 Renesas Electronics America Inc. All rights reserved. Questions? 58 © 2012 Renesas Electronics America Inc. All rights reserved. Enabling the Smart Society Energy efficiency is key to a Smart Society Energy harvesting Home Automation Smart Metering Industrial Motors Power quality is key to efficient energy management 59 © 2012 Renesas Electronics America Inc. All rights reserved. Renesas Electronics America Inc. © 2012 Renesas Electronics America Inc. All rights reserved.