Abstract: This paper provides a detailed description of the system design for collecting AC voltage and load current signals using the built-in ADC of HCNR200 and TMS320F2812. HCNR200 is a high-precision linear optocoupler specifically designed for analog signal isolation sampling. Its application can effectively isolate the main circuit from the control circuit while maintaining high linearity and minimal detection errors. The built-in ADC of the DSP is a 12-bit converter with high conversion accuracy, a short conversion time (12.5 MSPS), and a straightforward design.
Keywords: HCNR200; TMS320F2812; analog isolation; AC sampling
0 Introduction: In the design of a three-phase variable frequency power supply, it is essential to sample AC voltage and load current for dual-loop control and protection. Thus, the design of the AC voltage and current acquisition system is directly linked to the performance of the variable frequency power supply. The three-phase variable frequency power supply employs TMS320F2812 (referred to as F2812) as its control chip. The chip features a 16-channel, 12-bit ADC. Utilizing the F2812's built-in ADC for AC sampling eliminates the need for complex hardware design and reduces costs. The power supply requires an output line voltage of 380V and an output power of 3kW. To collect AC voltage and current signals and transmit them to the DSP chip, an isolation circuit must be designed to prevent high voltage and current from connecting to the control system and damaging low-voltage devices. HCNR200 is a specialized high-precision linear optocoupler for analog signal isolation. This article details the use of the F2812’s built-in ADC in combination with HCNR200 for AC voltage and current sampling.
1 Introduction to TMS320F2812 Built-In ADC: The TMS320F2812 chip, a 32-bit fixed-point DSP introduced by Texas Instruments at the end of 2003, is a high-performance controller that meets the real-time control requirements of motors. It operates at speeds up to 150 MHz and includes a built-in 16-channel, 12-bit ADC. Two channels of sample-and-hold, along with one conversion unit for dual-channel simultaneous sampling, provide a minimum conversion time of 80ns. The internal structure of the peripheral with the built-in ADC is illustrated in Figure 1.
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In recent years, the development of power electronics has led to increased demands for precise control systems. As such, the integration of advanced components like the HCNR200 and TMS320F2812 becomes crucial. The HCNR200, with its exceptional linearity and minimal error rates, ensures safe and accurate signal transmission between high-voltage circuits and control units. This feature is particularly important in industrial applications where reliability and safety are paramount.
The TMS320F2812's built-in ADC not only simplifies the design process but also enhances the overall efficiency of the system. With its fast conversion speed and high resolution, it allows for real-time data processing, which is critical in dynamic environments such as variable frequency drives. Additionally, the compact size and low power consumption of these components make them ideal for modern applications where space and energy efficiency are key considerations.
Furthermore, the integration of these technologies opens up new possibilities for future developments in renewable energy systems, motor control, and automation. By leveraging the capabilities of HCNR200 and TMS320F2812, engineers can create more robust and efficient systems that meet the growing demands of today's technological landscape.
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