Pre-Charging of a DC-Link Capacitor from a High Voltage Battery

Research output: Contribution to conferencePaperpeer-review


Pre-charging of DC-link capacitors limits the inrush current when connecting a power converterto the grid. In its simplest form, this can be realized with a relay parallel to a resistor and a diode as shown in [1] and [2]. This digest proposes an alternative approach for automotive onboard battery chargers that removes any need for such dedicated pre-charging hardware and completely avoids inrush currents. Instead, by exploiting the massive difference in energy storage between the mainbattery and the DC-link, the energy needed to pre-charge the DC-link capacitor can be reliably obtained using reverse power flow from the main battery through the isolating transformer, even if the main battery were to be almost entirely discharged. Furthermore, this paper shows methods how the battery and DC-link current can be easily limited with variable frequency control or varying duty cycle at constant frequency of the CLLLC output voltage when starting to charge an empty DC-link capacitor. Experimental verification of the control approach is done and it is shown that a charging time smaller than one second is possible.

Original languageEnglish
Publication statusPublished - 9 Nov 2020
Event21st IEEE Workshop on Control and Modeling for Power Electronics: COMPEL 2020 - Virtuell, Aalborg, Denmark
Duration: 9 Nov 202012 Nov 2020


Conference21st IEEE Workshop on Control and Modeling for Power Electronics
Abbreviated titleCOMPEL 2020
CityVirtuell, Aalborg
Internet address


  • Bidirectional energy Flow
  • CLLLC-Converter
  • DC-Link
  • Pre-Charging

ASJC Scopus subject areas

  • Control and Optimization
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering
  • Modelling and Simulation

Fields of Expertise

  • Mobility & Production

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