May 2020

www.epc-co.com POWER GaN 21 www.power-mag.com Issue 2 2020 Power Electronics Europe It improves dv/dt immunity that covers all eight types of switch-node transition events [9]. It simplifies PCB layout and reduces assembly component count for the converter solution. eGaN ePower TM stage Figure 2(a) shows the block diagram of the EPC2152 GaN ePowerTM Stage [2]. The main FETs are controlled by gate drivers within the IC that includes input buffers, a logic interface with Power-On- Reset (POR), Under-Voltage-Lockout (UVLO) functions, a high voltage, high dv/dt capable control signal level-shifter and a synchronous bootstrap [10, 11] that ensures proper high side voltage for the high side gate driver. The EPC2152 device is capable of interfacing to digital controllers that use standard CMOS or TTL logic levels, allowing it to be driven directly from a digital controller with 3.3 V signal levels, or from analog controllers that use voltage levels up to 12 V. Figure 2(b) shows a die photograph of the monolithic GaN power stage with pin allocations. It measures only 3.9 mm by 2.6 mm, or 10 mm 2 . Both FETs are rated at 80 V, and each has a typical R DSon of 10 m Ω . This IC can conduct peak motor phase load currents up to 15 A. Figure 3 shows a block diagram of a BLDC motor drive inverter featuring all the essential elements required for a high-performance drive ideal for electric mobility. Each of the half-bridge power stages use one EPC2152 ePower Stage and require only a few support capacitors, as can be seen in Figure 4 (top side) and is shown in a zoomed-in image in Figure 5. The motor phase currents are measured using shunts where the voltage is amplified using a high-performance shunt amplifier. Voltage measurement is from each phase to ground using a simple voltage divider resistor network. The same technique is used for the supply voltage measurement. Due to the high dv/dt’s generated by the GaN FETs, an LC-filter is included that can be configured as either a harmonic filter or EMI filter and comprises a line inductor and shunt capacitor. When configured as an EMI filter, a resistor is placed in series with the capacitor. This LC- filter is shown in Figure 4 (top side). BLDC motor drive for eScooter The motor drive is designed to operate from 15 V through 60 V DC input and power a 400 W BLDC motor such as the Figure 2 (a) above: Block diagram of the monolithic GaN ePower Stage, (b) below: die of the EPC2152 [2] LEFT Figure 3: Block diagram of the BLDC motor drive inverter