Solar energy equipment and EV chargers can use voltages from 200V to 1,50 V or more. Insulating materials help prevent these high-voltage terminals from inadvertently connecting to protective ground. If these insulating materials begin to deteriorate and the risk of exposure increases, then the potential for high-current faults, explosions, damage to equipment and property, or fatal accidents can occur.

Figure 11 shows the AFE for Insulation Monitoring in High-Voltage EV Charging and Solar Energy Reference Design, designed for insulation resistance monitoring in grid infrastructure applications using the TPSI2140-Q1 isolated switch and AMC3330 precision isolated amplifier. Because there are no moving parts, this solid-state relay solution can perform frequent measurements for decades without any performance degradation. These devices are designed for high-temperature operation up to 125°C, while alternative technologies such as photorelays are typically designed for operating temperatures up to 105°C. Both power and signals are transferable across isolation within these devices, so there is no need for secondary-side bias supplies. Since these devices are available in low-profile small outline IC packages, their solution size can be as much as 50% smaller than photorelay- or mechanical relay-based solutions. The ability to maintain accuracy over temperature makes it possible to detect and monitor insulation wear, and issue corresponding warnings or faults.

Solar string inverter and DC fast chargers contain high-voltage DC/AC and AC/DC power conversions. The photovoltaic panel output can go as high as 1,50 V and the DC fast charger output can go as high as 1,00 V, depending on the EV battery pack. For safety reasons, both systems require galvanic isolation.

To implement the voltage and current control loops in power-conversion systems, the microcontroller needs isolated, fast and accurate voltage and current readings. The AMC3302 isolated amplifier and AMC3306M05 isolated ADC both have a ±50-mV input range that enables small shunt resistors to keep power losses small and measurement resolutions high.

The Bidirectional Dual Active Bridge Reference Design for Level 3 Electric Vehicle Charging Stations (see Figure 12) uses a 10-kW bidirectional DC/DC converter. Peak power losses amount to less than 0.01% of the total power converted. An isolated power supply eliminates the need for a low-voltage supply on the hot side. The reference design uses the AMC1311 isolated amplifier for voltage sensing, while the UCC21530 isolated gate driver and ISO7721 isolated digital interface isolate low-voltage control signals from the high-voltage DC link or DC output.