Dual-core processor F28M35 in line protection applications

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

PESD1CAN electrostatic protection SOT23-3 24V two-way

Photocoupler

In the field of power protection, from the earliest 8-bit single-chip microcomputer, it has gradually developed to 16-bit and 32-bit processors, which basically meets the needs of microcomputer integrated protection devices. However, with the development of power industry technology, the computational complexity of protection algorithms has increased, and Ethernet communication technology has been widely used. The problem of insufficient capacity of mainstream processor TMS320F2812 in system management and network communication has been exposed.

In order to meet the new needs of users, the company has developed a new generation of integrated microcomputer protection device based on TI's dual-core processor, F28M35.

First, the characteristics of F28M35

The F28M35 processor is an industrial-grade dual-core processing control chip that integrates an ARM contex-M3 core and a DSP C28 core. The dedicated 4k ram and communication flag registers form the internal processor communication module - IPC.

The processor has up to 128KB of on-chip ram, of which 64K can be freely allocated between dual cores, program space 512KB + 512KB.

The M3 core has an address bus that can access up to 512MB of external data space. It is equipped with USB interface, Ethernet interface and traditional UART, I2C, SPI and other interfaces to meet most industrial control requirements. The system clock can reach 100MHz.

The biggest feature of the C28 core is the addition of a single-precision hard-floating point calculation unit, which brings great convenience to programming without sacrificing calculation speed and reduces the programming threshold. The highest system clock is still 150MHz.

Second, the hardware design of the protection device

The hardware of this system consists of voltage and current transformer, 16-channel A/D converter, open relay, LCD interface, key input, digital input, 485 communication interface, Ethernet communication interface, dual-core processor F28M35 and power supply. Part of the composition, its composition schematic is as follows:

Third, the protection device software task division and structure

1. The number of C28 core tasks is relatively small. The structure of the main program loop plus 200us interrupt can be used to complete the following tasks:

a. Operate two max125 14-bit 8-channel A/D converter chips and acquire 16 channels of AD value per 200us.

b. Perform software frequency measurement on each channel data to determine the frequency and period of the actual input AC signal.

c. According to the calculated period and the AD sampling value, 96 AD samples are virtualized per cycle per channel.

d. The main program performs a 96-point FFT operation to obtain the amplitude and phase of each channel.

e. The main program performs a higher harmonic FFT operation to obtain 2 to 11 higher harmonic amplitudes.

f. The main program performs all logic decisions to determine whether to perform a protection action.

g. Internal communication with the M3 core to complete data exchange in real time.

2. M3 nuclear management tasks are more, using UCOSII micro operating system to complete the following tasks:

a. The various menu parameters of the LCD screen are displayed and the button operations are corresponding.

b. Ethernet communication, RS485 communication and corresponding 103 reduction processing.

c. Settings of various system parameters (including setting through the communication port) and saving.

d. Action record and alarm record and save.

e. Record and save all analog input channels.

f. Internal communication with the c28 core to complete data exchange in real time.

Fourth, the implementation effect

By adopting the above technical solutions, the technical indicators of the whole machine are compared.

The similar products have improved a lot. The measured measurement accuracy of the 5A transformer reached 0.1% at 1A input, and the quick-break action time reached 24ms. At the same time, various network communication functions have been added, and the processor cost has hardly increased.

After the product is put into small batch production, the user has a good response and reliable and accurate work after long-term on-site operation assessment.

It can be seen that the dual-core processor F28M35 has a high cost performance and has a good prospect in industrial sites requiring high reliability, high real-time performance and complex functions, and will be widely used in the future.