High-frequency and precision three-phase sine/PWM controller with near-zero frequency of MPU intervention-novel design supporting distributed AC drive systems

Conventional pulsewidth-modulation (PWM) schemes fully depend on a microprocessor (MPU) for extensive real-time computation, intervention, and housekeeping, and are limited to applications at low fundamental frequencies and low precision. At 20-kHz switching, the overhead of a modern 16-bit CPU increases up to 90%, making virtually no time available for regular control tasks. It also has poor cycle-to-cycle accuracy of ±5-10 μs. A novel self-managed high-frequency and precision PWM architecture and integrated circuit are developed for distributed drive control systems. This architecture permits near-zero interfacing rate with the coprocessor, thus eliminating the overhead of the MPU´s intervention and housekeeping, while being capable of both asynchronous and synchronous PWM at a range of 0-1000 Hz of fundamental frequencies, expandable to several kilohertz. A cycle-to-cycle accuracy of 50 ns is achievable in precision open-loop control. Experimental results verify our new design. This effectively supports distributed ac drive systems with highly coordinated controls.