Although GaN devices may have a higher component price than comparable IGBTs, a system-level analysis reveals a different conclusion. When the impact on all major subsystems is considered, the TIDA-011008 design demonstrates that a GaN-based implementation can achieve approximately 11% lower total bill of material (BOM) cost than an equivalent IGBT-based design.

As shown in Figure 2-4, the most significant cost reductions are associated with magnetic components and capacitors. These savings are primarily enabled by the higher switching frequency supported by the GaN power stage.

To maintain high MPPT efficiency, the input voltage ripple of the boost converter must be minimized, requiring sufficient input capacitance. Because capacitance requirements are inversely proportional to switching frequency, a 100kHz GaN-based boost converter requires only about one-third of the input capacitance needed by a comparable 33kHz IGBT-based design. This reduction directly lowers capacitor cost and volume.

The higher switching frequency also benefits the EMI filter design. Since for a given EMI filter, normally the conducted differential mode noise attenuation typically improves with increasing frequency, a GaN-based design can achieve the same filtering performance with smaller x-capacitors. Together, these factors contribute significantly to the overall reduction in capacitor cost.

Magnetic components represent another major source of cost savings. The increased switching frequency substantially reduces the required inductance value in both the boost stage and the DC/AC inverter stage, enabling smaller inductors with lower volume and weight, also lower price. In addition, the common-mode choke can be optimized because higher-frequency common-mode noise is easier to attenuate, further reducing magnetic-component cost.

As mentioned in the TI GAN Module Description section, with integrated gate driver, a separate gate driver is not needed, in most cases, only a PWM buffer or digital isolator is required.

Beyond the BOM savings shown in Figure 2-4, the compact design benefited from reduction of passive components can also reduce the cost of housing, and can also lower storage, transportation and installation. While these savings are not included in the BOM comparison, they provide additional opportunities for reducing the total system cost of the inverter.

Figure 2-5 highlights the major components that benefit from 100kHz GaN operation. Reduced capacitor, magnetic, gate-drivers collectively contribute to the overall BOM cost reduction.

Figure 2-4 Cost Comparison Between IGBT and GaN-Based Designs

Figure 2-5 System Block Diagram