Power Factor Correction Why and How?

Transcription

1 Power Factor Correction Why and How? Renesas Electronics America Inc.

2 Renesas Technology & Solution Portfolio 2

3 Microcontroller and Microprocessor Line-up bit 8/16-bit 1200 DMIPS, Superscalar Automotive & Industrial, 65nm 600µA/MHz, 1.5µA standby 500 DMIPS, Low Power Automotive & Industrial, 90nm 600µA/MHz, 1.5µA standby 165 DMIPS, FPU, DSC Industrial, 90nm 242µA/MHz, 0.2µA standby 25 DMIPS, Low Power Industrial & Automotive, 150nm 190µA/MHz, 0.3µA standby 10 DMIPS, Capacitive Touch Wide Industrial Format & LCDs Automotive, 130nm 350µA/MHz, 1µA standby 1200 DMIPS, Performance Automotive, 40nm 500µA/MHz, 35µA deep standby 165 DMIPS, FPU, DSC Industrial, 40nm 242µA/MHz, 0.2µA standby Embedded Security, ASSP Industrial, 90nm 1mA/MHz, 100µA standby 44 DMIPS, True Low Power Industrial & Automotive, 130nm 144µA/MHz, 0.2µA standby 3

4 Enabling the Smart Society Energy efficiency is key to a Smart Society Home Automation Energy harvesting Smart Metering Industrial Motors Power quality is key to efficient energy management 4

5 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

6 PFC Market Drivers 6

7 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

8 What is Power Factor? Ammeter Wattmeter 120V 60Hz ~ A AP 5.1 A 400W AC Motor Real Power: Apparent Power: P = 400 W (Watts) S = 120V x 5.1A = 612 VA (Volt Ampere) Power Factor: PF = 400/612 = PF = P( W ) S( VA) 8

9 What is Power Factor? Where did the power go? P (W) AC voltage AC current Inductive Load φ φ S (VA) S Q (VAR) Displacement DPF = P( W ) S( VA) DPF = cosϕ Range: 0 1 Q(VAR): Reactive Power DPF = 1 when Q = 0 9

10 What is Power Factor? Total Harmonic Distortion (THD) Non-linear loads distort original AC current AC voltage AC current Distortion φ Displacement THD = 39 3 I 1 I 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) TPF = DPF 1 1+ THD 2 10

11 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 Bad PF: TPF = DPF 1 1+ THD 2 TPF <1 11

12 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

13 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

14 Power Factor Correction 14

15 Power Factor Correction AC voltage AC current 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 AC current 15

16 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

17 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

18 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

19 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

20 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

21 Implementation Example of Active CRM PFC PFC Boost Converter DC BUS T1 Rectified, unfiltered AC voltage Average AC current Critical Conduction Mode (CRM) Zero current detection TMX00 ANI0 Timer A/D TMX00 (PFC output) CMP+ Internal Vref Interlock MCU PFC-ON pulse width PFC-off pulse width CMP+ (Zero current detection) 21

22 Active PFC Topologies Single channel 120V AC ~ D1 L1 Q1 C PFC Cb Q1 IL1 120V AC Two channel interleaved ~ L2 D1 D2 L1 Q1 C PFC Q2 Cb Q1 Q2 IL1 IL2 Reduced current ripple IL1+IL2 22

23 Effect of High-frequency Switching Harmonics and inductor current ripple can disrupt other consumers Regulation standards apply IEC L 120V AC ~ C C L Q Higher ripple current will require better filters with multiple stages 23

24 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

25 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

26 Interleaved PFC versus Single Channel CCM topology for large power application (>300W) 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 26

27 Typical Application - Motor Control and PFC L D 3 Phase Inverter stage Fast Recovery Diode ( SiC) C 3 Phase Motor VAC T AC voltage, DC voltage current PWM Current, voltage, temperature, OC-detection PWM Gate Driver PFC Control IC MCU PWM Speed, Position 27

28 Digital PFC for Motor Control Inverter L D 3 Phase Inverter stage Fast Recovery Diode ( SiC) C 3 Phase Motor VAC T AC voltage, DC voltage current PWM Current, voltage, temperature, OC-detection PWM Gate Driver MCU PWM Speed, Position 28

29 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

30 Analog PFC Solutions 30

31 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

32 Renesas Analog PFC Controller Solutions CCM CRM Mode Part # Features Applications Interleaved R2A20114 R2A20104 Small current ripple Average SW noise More complex circuit Single R2A20115 Large current ripple Large SW noise Simple circuit Interleaved R2A20132 R2A20118A R2A20117 R2A20112 Small current ripple Average SW noise More complex circuit Single R2A20113 Large current ripple Large SW noise Simple circuit Server Air conditioner Induction heating Plasma TV PC Office automation Air conditioner Plasma TV PC Office automation LCD monitor AC adaptor LCD projector 32

33 CCM Interleaved PFC Controllers 2A20114/20104 Phase drop control input Internal / external clock can be used can use current transformer Current transformers 33

34 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

35 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

36 Digital PFC Solutions 36

37 PFC Control Functions VAC PF > V DC PFC Hardware VAC Gate PWM Inductor ripple current OC/OV Detection VDC VREF PFC Controller 37

38 PFC Control Functions Input/Output Control function Input Output Output voltage Feedback voltage Constant DC bus voltage AC voltage range AC voltage Adjust to VAC Inductor current IGBT current AC voltage Inductor current amplitude Synchronize with AC voltage phase Hardware protection Over-current Over-voltage Under-voltage Disable IGBT gate signals 38

39 Digital PFC for Motor Control Inverter L D 3 Phase Inverter stage Fast Recovery Diode ( SiC) C 3 Phase Motor VAC T AC voltage, DC voltage current PWM Current, voltage, temperature, OC-detection PWM Gate Driver Rx62T MCU PWM Speed, Position 39

40 Interleaved PFC Reference Design Auxiliary power DC/DC converter 395V 3.8A output VAC input Rx62T MCU board PFC CH1 PFC CH2 SIC Diodes 40

41 Complete PFC Solution from Renesas Diode: RJS6005TDPP-EJ (target) IGBT: RJH60F4DPK IGBT: RJH60F4DPK RX62T/100pin R5F562TAADFP 41

42 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 IGBT (RJH60F4DPK: 600V/50A) 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 35 khz / 1 phase x 2 9 Efficiency > 96 % 10 Power factor >

43 PFC Controller System Block Diagram PFC OUT 390V RX62T Multiplyer Deviation Current Controller Duty 1 Duty 2 PWM Timer1 OUT1 Gate Driver INPUT AC85~264V Voltage Controller Protection Controller PWM Timer2 OUT2 Gate Driver Deviation OCP setting + - ADC 12bit CS1 CS2 FB Voltage Reference OVP Setting VAC ADC 10bit OSC Controller CLK:100MHz CLK:50MHz GND HW SW Protection 43

44 Controller Implementation CS1 CC1 GD1 CS2 CC2 GD2 VAC VFB VC CS1,2 - Current sensing Ch1,2 VAC - AC Input voltage VFB - DC Output voltage CC1,2 - Current controller 1,2 VC - Voltage controller Control loops: Two-stage IIR filter 44

45 Program Flow Main Main ADC conversion interrupt Interrupt 10-Bit ADC 12-Bit ADC VAC CS FB ADC to voltage calculation Conversion start by GPT Conversion complete interrupt Voltage reference calculation Voltage controller Voltage IIR filter controller Current controller Current IIR filter controller PWM update GPT PWM duty update 45

46 RX62T MCU Resources Used Signal name 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 46

47 RX62T Peripherals used for PFC RX 62T 390VDC RX CPU (100 MHz) FPU Multiplier, Divider, Multiply, Accumulate 16-Bit MTU3 Ch 3&4 3-ph PWM Ch 6&7 3-ph PWM Ch 1&2 2 Encoder Inputs Ch 0 Hall / BEMF Input Ch 5 Dead-time compensation 16-Bit CMT 4 channel Multi purpose timer Flash up to 256KB Data Flash 8KB (30k times E/W) 12bit ADC 4-ch x 2 10bit ADC 12-ch RAM 16KB GPT 16-bit PWM Timer GPT0 16-bit PWM Timer GPT1 16-bit PWM Timer GPT2 16-bit PWM Timer GPT3 3 PGA 3 Comp x 2 ~ GD1 GD2 CS2 CS1 VFB VAC IL2 GD2 0.02Ω IL1 0.02Ω upc844g2 FB upc844g2 CS1 upc844g2 CS2 47

48 Gate Drive, Synchronized ADC sampling Average coil current 1 IL1 upc844g2 Duty set 1 Timer count 1 FBVFB GD1 GD1 upc844g2 IL2 0.02Ω CS1 CS1 180deg phase shift IGBT current 2 Average coil current 2 GD2 Duty set Ω upc844g2 CS2 Timer count 2 GD2 GD1 period Tn Tn+1 Tn+2 GD2 period Tn Tn+1 Tn+2 CS1 ADC sampling CS2 ADC sampling FB ADC sampling 48

49 Overvoltage Protection by Hardware - Example of PFC and DC/DC converter PFC-OUT +5V 2MΩ PFC-FB 10k 18.56kΩ 3.33V OVP_PFC PWM-OUT 20kΩ PWM-FB 3.33V 5.1kΩ 2kΩ OVP_PWM PFC-OUT * 2 POE0# MTIOC3B * 1 PFC-GD1 PWM-OUT RX62T MTIOC4A PFC-GD2 MTIOC4B PWM-GD R5F562TAADFP * 1. Protection by external hardware * 2. Protection by internal hardware by POE function 49

50 Feedback Signal Measurement by 12-Bit ADC ADC unit 0 VFBPF_IN AN000/AN101 PGA S/H Data Register 0 VCSPF1_IN VCSPF2_IN AN001/AN101 AN002/AN102 PGA PGA S/H S/H Multiplexer ADC Data Register 1 Data Register 2 VAC_IN AN003/AN103 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

51 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 AD trigger CPU Interrupt GPT0 GPT1 GTIOC0A-A/B GTIOC0B-A/B GTIOC1A-A/B GTIOC1B-A/B GTCCRA0 GTIOC0A-A OFF GPT0.GTCNT ON OFF ON OFF AD trigger CPU Interrupt AD trigger CPU Interrupt GPT2 GPT3 Output protect GTIOC2A-A/B GTIOC2B-A/B GTIOC3A GTIOC3B POE3 GTCCRA1 GTIOC1A-A GPT1.GTCNT ON OFF ON OFF ON CPU interrupt for POE 1. GTPR0,1: PWM frequency(35khz) 2. GTCCRA0,1: PWM duty 51

52 Example of PFC Control Trigger by GPT0 GPT0.GTCNT Counter value GTP0.GTPR PFC Cycle hhhh ffff eeee dddd cccc bbbb aaaa Register write Register write Register write Register write Time GTP0.GTCCRC PFC Duty Cycle ffff dddd hhhh Buffer transfer at crest Buffer transfer at through Buffer transfer at crest bbbb ffff dddd hhhh GTIOC0A output PFC gate drive GTADTRA ADC Trigger ADC conversion start ADC conversion end ADC conversion end interrupt PFC control start t PFC control end 52

53 CPU BW for Interleaved PFC: Control loop processing: 4.5us 9us (32%) 4.5us PFC control timing 28us GD1 53

54 AC Current 100V AC input 100V AC Input Input AC voltage Input AC current Inductor current Output voltage ripple 54

55 Rx62G High Resolution PWM Timer Each GPT channel can generate HR-PWM for two outputs independently Minimum resolution is 1/32 of normal resolution: rising falling GTDLYRA GTDLYFA GTTCRA GTTCRA GTDBD GTDVD Controller GTDBU GTDVU GTPDBR GTPBR GTPR Input control Comparator input External Trigger. GTIOCA AD trigger CPU Interrupt GTCNT Comparator GTADTRA GTADTBRA CPU interrupts GTADTRB GTADTBRB GTADTDBRA GTADTDBRB GTCCRB GTCCRE GTCCRF GTCCRA GTCCRC GTCCRD High resolution Output control Output protect PWM1 PWM2 POEx GTDLYRA 15 Upper 16bit 0 GTTCRA GTDLYFA Lower 5bit 0 GTDLYRA GTDLYFA 55

56 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

57 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

58 Questions? 58

59 Enabling the Smart Society Energy efficiency is key to a Smart Society Home Automation Energy harvesting Smart Metering Industrial Motors Power quality is key to efficient energy management 59

60 Renesas Electronics America Inc.