Article ID: 25000231
Current source inverters (CSIs) offer advantages over voltage source inverters (VSIs) in drive systems, particularly for motor windings. CSIs feature integrated output capacitors that provide smooth voltages, mitigating issues such as interturn overvoltages, insulation degradation, bearing currents, and electromagnetic interference. Recent advancements in monolithic bidirectional switches have further enhanced their appeal. However, the complexity of CSI modulation and control limits their adoption compared to VSIs, as engineers are more familiar with PWM techniques for VSIs. To address this, we propose the Equivalent DC Machine (E-DCM) concept, wherein the CSI operates in an open loop with a fixed modulation index, allowing direct torque control of the PMSM through the DC link current. This enables the CSI-supplied PMSM to emulate the behavior of a traditional DC machine, simplifying control while avoiding commutation and maintenance issues. The E-DCM concept is validated through transient time-domain simulations, demonstrating its DC machine-like speed-torque characteristics and effective speed control during acceleration from zero to nominal speed.
