600 W DC/AC Inverter for Reliable On-Board Power in Railway Rolling Stock
Reference Project – True Sinewave Power Conversion for Railway Applications
Sector: Rail
Application: Rolling stock – decentralized 230 VAC power supply for passenger areas, including mobile phone charging, laptop charging and other onboard AC loads.
Background and Requirements
Modern railway vehicles require reliable, compact and standards-compliant power conversion systems that can be connected directly to the train auxiliary supply. In passenger areas, the power supply must deliver a stable and clean AC voltage to support sensitive electronic devices such as chargers, laptops and mobile equipment.
For this rolling stock application, the customer required a robust DC/AC inverter with a true sinewave output, very low distortion and a protected enclosure suitable for demanding railway environments.
The main requirements included:
- True sinewave 230 VAC output
- Very low output distortion
- Direct connection to the train auxiliary supply
- Integrated surge and transient filtering
- Protection up to IP65
- Compliance with railway EMC and protection requirements
- Shock and vibration resistance for rolling stock use
- Compact design for installation in space-limited areas, such as behind seats
Technical Solution
The selected solution was the ASP750-B/1 from LPA / Martek Power, the 24 VDC input version, derated to 600 W.
The ASP750 series is designed for railway applications and provides a 230 VAC true sinewave output with very low distortion. The inverter is suitable for direct connection to the train auxiliary supply and incorporates surge and transient filtering to support compliance with both traditional and latest railway specifications for protection and EMC.
Depending on the input version, the ASP750 series provides up to 750 W continuous output power. The ASP750-B/1 supplied for this project is the 24 VDC input version and is derated to 600 W continuous output power. The inverter provides reliable onboard AC power for passenger and service applications. It operates with a typical efficiency of 85% and delivers a 50 Hz output frequency.
The fully enclosed aluminium housing, convection cooling and IP65-rated main enclosure make the unit suitable for harsh railway environments. Its low-profile mechanical design supports installation behind seats or in other space-constrained locations.
Technical Highlights
- Continuous output power: 600 W for the ASP750-B/1 24 VDC version used in this project
- Peak power: up to 800 W for 15 seconds, depending on input version
- Output voltage: 230 VAC true sinewave
- Output frequency: 50 Hz
- Typical efficiency: 85%
- Input voltage range: 16.8–33.6 VDC for the 24 VDC input version
- IP65-rated main enclosure
- Convection-cooled aluminium housing
- Integrated surge and transient filtering
- RCBO output protection
- Short-circuit, overload and thermal protection
- Automatic recovery
System Integration
Within the rolling stock power architecture, the ASP750-B/1 converts the available 24 VDC auxiliary voltage into a stable 230 VAC supply. The unit has an input voltage range of 16.8–33.6 VDC. This enables decentralized AC power distribution for passenger comfort functions and onboard equipment.
The inverter includes output protection via an RCBO, combining residual-current and overcurrent protection, located behind a lockable access door. Additional protection functions include short-circuit protection, overload protection, thermal shutdown and automatic recovery.
