AC-DC Rectifiers

PFC · Vienna · active front end

Every charger, server and battery system starts with a rectifier. Its topology decides power quality, efficiency and whether power can flow back to the grid.

Where the rectifier sits: AC grid, EMI filter, rectifier with power factor correction, DC link, then a DC-DC converter or inverter; the rectifier can be a diode bridge, a Vienna rectifier or an active front end. Below, typical rectifier stage power on a log scale: server power supply 5.5 kW, onboard charger 11 kW, DC charger power module 40 kW, ultra-fast charger 400 kW, Megawatt Charging System truck charger 3.75 MW, and an electrolyzer rectifier about 20 MW. WHERE THE RECTIFIER SITS AC grid EMI filter Rectifier/PFC DC link DC-DC/DC-AC diode bridge, Vienna or active front end; sets power factor and harmonics RECTIFIER STAGE POWER BY APPLICATION (LOG SCALE) Server PSU5.5 kW Onboard charger11 kW Charger module40 kW Ultra-fast charger400 kW MCS truck charger3.75 MW Electrolyzer20 MW 1 kW 100 kW 10 MW
Span
watts to tens of MW
Charger default
Vienna rectifier
Bidirectional
active front end
Hub
Supply Chain

Finding

DC fast-charger rectifiers have become a commodity module business led by Chinese makers, while the differentiation moves to cabinet design, uptime and grid compliance

A DC fast charger is a stack of 20-50 kW AC-DC power modules, most built around a three-phase Vienna rectifier with SiC or silicon devices behind it. Infypower, UUGreen, Tonhe and Sinexcel in China ship these modules at a scale few Western suppliers match.

The same pattern runs through other markets. Data center and telecom rectifier shelves come from Delta, Vertiv, Huawei, Eaton and Schneider; Nvidia's 800 V DC rack architecture, announced in 2025, moves rectification out of the rack to the facility edge, pulling SiC into the front end and GaN into the downstream DC-DC stages. Electrolyzers and aluminum smelters use thyristor or IGBT rectifiers rated in the tens of megawatts.

Topology follows the job. Diode bridges are cheap and rugged but draw distorted current. Boost PFC stages fix power factor in single-phase onboard chargers and server supplies. Vienna rectifiers give high efficiency and low harmonics in one direction only. Active front ends are fully controlled PWM bridges that can push power back to the grid, which vehicle-to-grid chargers, battery storage and regenerative drives require. Harmonic limits in IEEE 519 and IEC 61000-3-2 and 61000-3-12 push designs toward active stages.

Topologies

Rectifier topologies

Main AC-DC rectifier topologies
TopologyAdvantagesTradeoffsCommon applications
Full-wave diode bridgeSimple, robust, lowest costNo current shaping; high harmonicsBasic supplies, welders, DC buses behind a PFC stage
Thyristor (controlled) rectifierControllable output, rugged at very high powerPoor power factor at partial load, harmonicsElectrolysis, smelting, legacy industrial drives
Boost PFCNear-unity power factor, regulated DC busExtra switching loss and controlOnboard chargers, server and telecom supplies
Vienna rectifierHigh efficiency, low device stress, low harmonicsUnidirectional onlyDC fast-charger modules, telecom, aerospace
Active front end (AFE)Bidirectional, low harmonics, regenerationCost, EMI, control complexityV2G chargers, BESS, regenerative motor drives
Half-waveFewest partsHigh ripple, poor efficiencyLegacy and very low-power circuits only

EV charging

Where rectification happens on the EV power path

In AC charging the rectifier is in the car; in DC charging it is in the cabinet.

Rectification in EV charging
Power pathWhere rectification happensDesign priorities
Level 1 and Level 2 ACOnboard charger in the vehicleSize, cost, efficiency, isolation
DC fast chargingOff-board charger cabinet, stacked power modulesPower density, modularity, grid compliance, uptime
Bidirectional / V2GActive front end, onboard or off-boardTwo-way flow, harmonics, grid codes, cybersecurity
Megawatt Charging SystemOff-board high-power AFE or Vienna stagesEfficiency, cooling, parallel module control

Devices

Devices and supporting parts

Semiconductors and components in the rectifier stack
PartRoleStrengthsLimits
Silicon diodes and thyristorsPassive or phase-controlled rectificationCheap, rugged, very high currentConduction loss, harmonics
IGBTsActive front ends at medium and high powerHigh voltage, broad supplySwitching loss at higher frequency
SiC MOSFETs and diodesVienna and AFE stages in chargers and storageLow loss, high frequency, smaller coolingCost, gate-drive and packaging demands
GaN transistorsCompact high-frequency PFC at low to mid powerVery fast switching, high density650 V class; power range
Magnetics and capacitorsPFC inductors, EMI filters, DC-link capacitorsSet ripple, EMI and sizeOften the real size and lead-time constraint
Control siliconDSPs and MCUs (TI C2000, Infineon, ST)Run current loops and grid codesQualification cycles slow substitution

Sources

Sources and scope

Scope
AC-DC Rectifiers
Sources
IEEE 519; IEC 61000-3-2/-3-12; CharIN MCS; Nvidia (800 V DC architecture, 2025); supplier disclosures
Updated
October 2026