**3. Space charge measurement system**

Using the pulsed electroacoustic (PEA) method which is described above, we developed several space charge measurement systems for high temperature. **Figures 3** and **4** shows the developed system [2, 3]. On the **Figure 3**, it is the developed PEA system for high temperature (up to 80 °C). This system is enabled to measure the space charge accumulation in dielectric materials. In this system, temperature (30–80 °C) of silicone oil is control using a band heater and a controller.

Furthermore, as the IGBT using SiC is operated over 150 °C, the space charge measurements under more high temperature are also required. Therefore, we developed newly PEA system for high temperature (up to 150 °C), which is shown in **Figure 4**. From the figure, to measure the space charge distribution at high
