High-Isolation DC/DC Converters Meet Green Requirements

Solar energy is the cleanest, most abundant global renewable energy source, and plays a key role in the development of sustainable energy systems. Global photovoltaic (PV) generation capacity has undergone exponential growth over the past decade. Approximately 183GW was added in 2021, bringing estimated global PV installations to over 1000GW (one terawatt).

The US Dept of Energy plans to install 5TWh of grid storage capacity by 2050 to meet US energy needs alone. Solar power conversion systems transform solar energy into electrical energy that is either fed to utility grids or used by off-grid electrical networks. The harvested electrical energy is processed by power converters.

The PV solar panel produces a high-voltage DC output that is converted to AC by a high-voltage three-phase inverter. Figure 1 shows the block diagram of a typical transformer-less solar power conversion system with IGBTs in the inverter stage.


The converter uses both high-voltage and low-voltage circuits. The DC rail voltage can be 1000V or higher, and the inverter module is often floated by a few hundred volts above ground, so isolation is required for both functional and safety purposes.

Optocouplers provide isolation for control signals, but the gate driver power supply must also be isolated. This isolated supply consists of a DC/DC converter that supplies typically +15/-9V for IGBT devices, +20/-5V for SiC MOSFETs (+15/-3 V for 2nd Gen. devices), or +6 V and +9 V for GaN HEMTs. The simplest (functional) isolation of a DC/DC converter can withstand 1 kV DC for one second. However, this is often not sufficient for high-side gate drivers. A typical DC/DC isolation voltage would be at least twice the working voltage, but the high ambient temperature and fast switching edges generated by these high-power transistors additionally stress the insulation barrier. As a result, highly isolated DC/DC converters are needed to power the gate drivers.

A RECOM isolated DC/DC converter provides a simple power solution for an isolated gate driver design, no matter whether IGBT, SiC MOSFET, or GaN power devices are used. RECOM offers a range of isolated DC/DC converter modules that provide an efficient power solution for IGBT, SiC MOSFET, or GaN HEMT power devices. Features of these converters include asymmetric output voltages, high insulation voltage, and low isolation capacitance.