1 Introduction to Real-Time Control

In real-time control, a closed-loop system gathers data, processes it in a control loop, and makes updates within a defined time window. Signal chain performance quantifies real-time control performance, where higher performance enables faster closed-loop systems. A real-time control system is typically composed of three main elements:

• Sensing or feedback acquisition: The application can require the accurate measuring of key parameters (such as voltage, current, motor speed, motor position, and temperature) at precise moments in time.
• Processing and Control: Use sensor data to apply control algorithms on incoming data to compute the next output command.
• Actuation: The application of the calculated output command to the system to control the output. Changing the duty cycle of a pulse width modulator (PWM) unit driving a power electronics system is an example of actuation.

In real-time control, performance of the system is determined not just by the processing power of the CPU, but also how fast peripherals are accessed the speed of the interrupt response. These factors lead to the notion of a real-time signal chain.

Figure 1-1 illustrates various components involved in a typical real-time signal chain of motor control and digital power systems. Better signal chain performance enables higher DC bus use and the operating speed range of a motor in motor control applications. In digital power applications, better signal chain performance enables higher control loop frequencies leading to smaller components and lower cost.

Components 1, 2, and 4 are dominated by the CPU architecture while components 3 and 5 are dependent on CPU and device architecture. This paper primarily highlights improvements in components 1, 2 and 4. Additionally, C2000 MCUs offer low latency interconnect, enabling single-cycle ADC reads and single-cycle PWM updates.