Design Considerations for High Switching Frequency PWM Inverter for UPS Application Using Hybrid Darlington Switches

This paper investigates the suitability of ‘hybrid darlington’ as the switching element in high switching frequency (10-20 KHZ) PWM inverters intended for UPS systems. The inverter employs stored waveform patterns for Sinusoidal Pulsewidth Modulation. The drive requirements for such a device are discussed and a drive circuit suitable for use in the inverter is presented with experimental results. The imperfections such as low order harmonics introduced because of the switching speed limitation of the hybrid darlington and their impact on the selection of the system parameters such as switching frequency, clock rate, memory size are discussed with analytical and experimental results.