Vicor Corporation · NASDAQ:VICR
Vicor — Technical Presentation (2019)
47 slides from Vicor's technical presentation, Nov 20, 2019
Slide 1: Modular DC-DC System Design Done Right
Modular DC-DC System Design Done Right Authors: Jon Siegers, Sr. Applications Engineer Vamshi Domudala, Applications Engineer ©2019 Vicor 1
Slide 2: Contents
Contents DC-DC Modules – System Design Process and Example System Integration and Support Circuitry – Power Source and Decoupling – Input Filter and Stability Analysis – Output Filter and Transient Response – Special Load Considerations – Safety and Protections – Current Sharing and Fault Tolera
Slide 3: DC-DC Power Modules
DC-DC Power Modules High performance Flexibility Faster development Delivering power reliably and Modularity is a key benefit Shorten design time with efficiently is paramount in and provides flexibility to building-block approach to modern systems construct complex power power system construc
Slide 4: System Design Process
System Design Process Identify system Develop system Implementation of requirements and architecture and select modules and module options power components to support circuitry High-level definition of fulfill conversion needs Finalize module system operation Is this a complete system configur
Slide 5: Identify System Requirements
Identify System Requirements: What operating conditions must the DC-DC system fulfill? Tabularize the system Output # VIN VOUT IOUT Notes operating voltages, currents, power levels Tight voltage regulation, Keep track of any 1 1.2V 120A 200A peak current needed special trim ranges or operating C
Slide 6: System Architecture and Block Diagram
System Architecture and Block Diagram Start by laying out the system outputs ? 1.2V, 130A ? 2.2V, 60A ? 3.3V, 7.5A ? 5V, 20A ? 24V, 12A ? 48V, 16A ©2019 Vicor 6
Slide 7: System Architecture and Block Diagram
System Architecture and Block Diagram VTM Partition the system and PRM 1.2V, 130A identify power module class VTM – Consider physical constraints of system, including: Available space for power module location PRM VTM 2.2V, 60A Needs for isolation 48V Special PDN architectures niPOL 3.3V, 7.
Slide 8: System Architecture and Block Diagram
System Architecture and Block Diagram VTM Work back towards the input, 90.3% PRM 1.2V, 130A using data sheet efficiency estimates to compute VTM upstream conversion power requirements 89.7% BUS PRM VTM 2.2V, 60A 96.2% CONV 48V, 8.9A 88.6% BUS niPOL 3.3V, 7.5A CONV 4.2A 92.2% 384V (N+1) niPOL 5V, 2
Slide 9: System Architecture and Block Diagram
System Architecture and Block Diagram VTM Refine system efficiency estimates and 90.3% PRM 1.2V, 130A incorporate late power requirement changes VTM VTM 90.5% BUS PRM 2.2V, 120A CONV VTM 96.9% 48V, 12A 88.6% BUS niPOL 3.3V, 7.5A CONV 4.6A 92.2% 384V (N+1) niPOL 5V, 20A 92.0% DC/DC 24V, 12A 384V, 3
Slide 10: Implementation and Support Circuitry
Implementation and Support Circuitry A module or collection of modules is not a complete power system Compliance with EMI standards requires additional filtering Protections are often narrow and limited to the module only Source and load characteristics dictate decoupling needs Specialized l
Slide 11: What Else Do I Need?
What Else Do I Need? 1. Source and ZIN_CONVERTER 8. Output Line Source 3. Safety 5. Input Impedance 7. Output Filter Impedance Filter R2 Isolated DC-DCConverter Lin Rin Ld Rd F1 Ld Rd +IN +OUT L2 CY1 CY1 L CDECOUPLE Transient + O C3 Suppression C3 - Vin C4 A Circuit D RESR_Decouple CY2 CY2 -IN -OUT
Slide 12: Power Source Interconnection
Power Source Interconnection ©2019 Vicor 12
Slide 13: Defining the Power Source
Defining the Power Source Understanding the characteristics of the DC power source is critical for ensuring system performance and stability – Large-signal characteristics Available power Range of supplied voltage Behavior during dropouts or other non-linear behaviors – Small-signal characte
Slide 14: Filtering
Filtering ©2019 Vicor 14
Slide 15: Filtering: What are the noise sources in a power system?
Filtering: What are the noise sources in a power system? Switching action and parasitics tend to generate noise currents Two types of noise currents are generated – Common-mode noise – Differential-mode noise ©2019 Vicor 15
Slide 16: Filtering: Electromagnetic interference
Filtering: Electromagnetic interference Problems associated with noise interference – Erratic system operation – Sensitivity to noise generated by neighboring systems Input filters bypass the switching converter noise locally to ground – Reduces interference with other systems connected to the s
Slide 17: Filtering: Does it need to comply with any standards?
Filtering: Does it need to comply with any standards? Depending on the application the EMI filter Application Category Standard have to meet certain EMC standards EMC: Electromagnetic compatibility Defense MIL-STD-461 EMI : Electromagnetic interference EMC standards are regulated by various Comm
Slide 18: Filtering: Noise-mitigation techniques
Filtering: Noise-mitigation techniques Usually requires several discrete components – Common-Mode Elements – Differential-Mode Elements Common-mode choke, Y-capacitors Inductors, X-capacitors, damping elements EMI Filter Isolated DC-DCConverter CY1 CY3 CY5 + +IN +OUT Llkg DC Power RESR_Decouple
Slide 19: LC Filter Topology Attenuation Characteristics
LC Filter Topology Circuit Diagram Attenuation Characteristics Undamped Frequency Response Plot Simplified series-damped Series-damped Parallel-damped ©2019 Vicor 19
Slide 20: System Stability Analysis
System Stability Analysis Standalone Stable Regulated modules may interact unexpectedly with power source impedance Frequency-dependent, finite source impedance – Power source bandwidth limitations System – Cable length Minor Loop – Filtering Gain Im Regulated DC-DC modules appear as constant-po
Slide 21: Source Impedance Decoupling Capacitor Design
Decoupling Source Impedance Capacitor Design ZSOURCE ZIN-CONVERTER ZSOURCE-C = (ZSOURCE-IN + ZLINE) // (ZC + ESR) ZIN-CONVERTER ZSOURCE-IN ZLINE ZSOURCE-IN + + + DC-DC + C DC-DC _ _ _ Converter ESR _ Converter LLINE RLINE LLINE RLINE Source Impedance 2 10 ZSOURCE ZIN-CONVERTER 1 10 Impedance ( ) 0
Slide 22: Filtering: Input filter stability with source
Filtering: Does the input filter introduction cause stability issues with source? ZTOTAL-SOURCE ZIN-CONVERTER Interaction between ZTOTAL_SOURCE and + ZIN_CONVERTER results in DC-DC converter Source Load + - Vin Vout Load Subsystem Subsystem control-loop instability, degradation of - dynamic perfor
Slide 23: Output filter design
Output filter design Based on the application’s transient Vout-converter Vout-load requirements, select the filter L inductor using below equation DC-DC C Load Converter Select filter cut-off frequency to meet the attenuation characteristics Load Current Find filter capacitor value using diloa
Slide 24: Filtering: Impact of PCB layout on filter performance
Filtering: Impact of PCB layout on Is physical location important? filter performance? Physically locate EMI filters close to the Minimize trace inductance and trace resistance switching converters Provide keep-out area to avoid parasitic capacitance – Minimizes the effect of trace resistance
Slide 25: Filtering: Component de-rating and cold-temperature performance
Filtering: Component de-rating and cold-temperature performance The value of the capacitor changes over applied voltage, temperature, frequency and aging Characteristic X7R Tantalum Polymer Aluminum Polymer Aluminum Electrolytic Temperature (/) ±15% ±10% ±10% 25 to –30% DC voltage coefficient (%) at
Slide 26: Load Considerations
Load Considerations ©2019 Vicor 26
Slide 27: Load Characteristics
Load Characteristics Dealing with Inductive Loads Affects Affects At the turnoff instance, the energy stored in the Load Type control loop transient inductive loads will generate response response Large negative voltage spikes Resistive Load High-frequency noise or EMI that can affect DC-DC conv
Slide 28: Loads: Pulse Loads
Loads: Pulse Loads Power Averaging DC-DC converters sized for peak load DC-DC Converter factors to consider: requirements add unnecessary size, weight – Current and power limit and cost – DC-DC converter capacitance limits – Support circuitry such as bypass capacitors, – Stability of the DC-DC c
Slide 29: Safety and Protections
Safety and Protections ©2019 Vicor 29
Slide 30: Fusing Requirements
Fusing Requirements Safety Agency Conditions of Acceptability require power module inputs be fused – Consult latest available module safety agency documentation for fusing requirements Fuses are a critical safety element, performing two main functions – Limit the extent of thermal damage and pre
Slide 31: Fuse Placement
Fuse Placement F1 F2 HVDCIN Bus Conv BUSCONV niPOL niPOL SELV OUT 1 SELV BUS F3 niPOL niPOL SELV OUT 2 ©2019 Vicor 31
Slide 32: Fuse Selection: Current Rating and Temperature Re-rating
Fuse Selection: Current Rating and Temperature Re-rating Usually greater than the maximum continuous Typical Temperature Re-Rating Chart (Fast-Acting Type) operating current of the protected system 140 Percent Specified Current Rating (%) – In regulated systems this condition occurs at 120 minimum
Slide 33: Fusing: Voltage and Interrupt Current Rating
Fusing: Voltage and Interrupt Current Rating DC voltage rating of fuses correspond to the maximum withstand voltage tolerable and must not be exceeded – Fuses are not responsive to voltage fluctuations – Voltage rating of fuse must meet or exceed the maximum expected voltage of the application – P
Slide 34: Fusing: Nominal Melting I2t
Fusing: IPK IPK Nominal Melting I2t 0.5 IPK Frequent pulse current overloads lead to t t0.5 premature thermal fatigue of fuse element – Module start-up inrush – Capacitive charging – Externally introduced transients Number of Surge Pulses Pulse Factor (PF) Determine fused system’s expected pulse
Slide 35: Additional Fusing Considerations
Additional Fusing Considerations Fuses should be installed on the ungrounded side of the circuit to ensure an uninterrupted connection to low potential is present when the fuse is opened Consider special environmental conditions of the application. – e.g., Fuses are not directly suitable for sub
Slide 36: Spike and Surge Transients
Spike and Surge Spike (<1ms duration) Transients V90% fosc Power modules must be withstand input voltage V10% transients outside of specified operating range – Inductive load switching, motor speed changes – Fault clearing or momentary power interruptions trise tduration Level of transient suppr
Slide 37: Two-Stage Transient Protection Circuit
Two-Stage Transient Protection Circuit TVS diodes provide fast transient Q1 suppression on the order of 100μs High voltage, low energy spike clipping – Typically coupled with a low-Q LC filter for larger D1 energy transients Upstream fuse needed to protect TVS diode D2 Charge Series combinatio
Slide 38: Two-Stage Transient Protection Circuit
Two-Stage Transient Protection Circuit Active clamp stage reduces blocks longer duration surge voltages Q1 – FET selection dependent on the acceptable input voltage range of the module – Oscillator and charge pump for high side D1 N-channel FET drive N-channel preferred for generally lower RDSON c
Slide 39: Current Sharing and Fault-Tolerant Arrays
Current Sharing and Fault-Tolerant Arrays ©2019 Vicor 39
Slide 40: Current Sharing of Module Arrays
Current Sharing of Module Arrays Parallel modules to expand total output power DC-DC Converter 1 IIN1 IOUT1 capability of system +IN +OUT + – Be aware of any power de-rating for VOUT1 arrayed modules -IN -OUT - CPara Start up into load capacitance L + O – Fault recovery coordination - Vin A D DC
Slide 41: Array Input / Output Filtering: Decoupling for beat frequencies
Array Input / Output Filtering: Decoupling for beat frequencies Undesired beat frequencies at the common input and output bus – Part-to-part variability results in slightly different switching frequencies – Circulating AC ripple currents can cause interference leading to system stability and Lb_1
Slide 42: Redundant Operation
DC-DCConverter 1 D1 IIN1 IOUT1 +IN +OUT + Redundant Operation -IN CPara -OUT VOUT1 - L + O - Vin A Fault-tolerant arrays prevent system IIN2 DC-DCConverter 2 D2 IOUT2 D downtime due to module failure +IN +OUT + VOUT2 – Addition of extra module (N+1) or modules - (N+M) increases reliability with mo
Slide 43: Signaling and I/O
Signaling and I/O ©2019 Vicor 43
Slide 44: Control: Typical control I/O
Control: Typical control I/O Analog interface Digital / PMBus® interface – Control – Control Output voltage trim Output voltage trim Enable/disable Enable/disable Fault protection set points (Input – Monitoring UVLO, OVLO, current limit etc.) Fault – Monitoring Temperature Fault
Slide 45: Control: Remote sense
Control: Ld Rd Remote sense +IN +OUT +Sense L O DC-DCConverter A D Remote Sense function of modules -Sense -IN -OUT negate effect of line impedances on Ld Rd voltage regulation Output Line Impedance – Integrated within module, pins provided +IN +OUT Ld Rd – External loop and compensation L O netwo
Slide 46: Control: Signal vs. power grounds
Control: Signal vs. power grounds Differentiating signal vs. power grounds will avoid potential noise interference from the power grounds to the signal grounds – Power grounds carry much larger currents and consists of switching noise generated the DC-DC converter’s switching action – Due to the t
Slide 47: Thank you
Thank you Questions? The information contained herein and presented by Vicor is for general informational purposes only. Vicor assumes no responsibility for inaccuracies, errors or omissions in this presentation. Users of power supply products remain responsible for the design, testing and operation