Freescale 56F8000系列光伏电压逆变器方案

Freescale 公司的56F8367 和 56F8167基于56800E内核的数字信号控制器(DSC),每个器件集成了DSP处理功能和具有灵活接口集的微控制器功能,具有低成本,灵活配置和紧凑的程序代码, 56F8367 和 56F8167有广泛应用,包括工业控制,安全系统,马达控制,家用电器,汽车电子,数字电源转换等. 而56F8000 DSC系列非常适合光伏电压逆变器控制.本文介绍了56F8000 DSC系列中的56F8367 和 56F8167主要特性,方框图,内核特性以及小于3KW离线光伏电压逆变器方框图, 1-10KW连接电网的住宅区光伏电压逆变器方框图和大于10KVA连接电网的商用光伏电压逆变器方框图.

56F8367/56F8167 General Description
The 56F8367 and 56F8167 are members of the 56800E core-based family of controllers. Each combines, on a single chip, the processing power of a Digital Signal Processor (DSP) and the functionality of a microcontroller with a flexible set of peripherals to create an extremely cost-effective solution. Because of its low cost, configuration flexibility, and compact program code, the 56F8367 and 56F8167 are well-suited for many applications. The device includes many peripherals that are especially useful for motion control, smart appliances, steppers, encoders, tachometers, limit switches, power supply and control, automotive control (56F8367 only), engine management, noise suppression, remote utility
metering, industrial control for power, lighting, and automation applications.

The 56800E core is based on a Harvard-style architecture consisting of three execution units operating in parallel, allowing as many as six operations per instruction cycle. The MCU-style programming model and optimized instruction set allow straightforward generation of efficient, compact DSP and control code.

The instruction set is also highly efficient for C/C++ Compilers to enable rapid development of optimized control applications.
The 56F8367 and 56F8167 support program execution from internal or external memories. Two data operands can be accessed from the on-chip data RAM per instruction cycle. These devices also provide two external dedicated interrupt lines and up to 76 General Purpose Input/Output (GPIO) lines, depending on peripheral configuration.

56F8367 和56F8167主要特性:
Up to 60 MIPS at 60MHz core frequency
DSP and MCU functionality in a unified, C-efficient architecture
Access up to 4MB of off-chip program and 32MB of data memory
Chip Select Logic for glueless interface to ROM and SRAM
512KB of Program Flash
4KB of Program RAM
32KB of Data Flash
32KB of Data RAM
32KB Boot Flash
Up to two 6-channel PWM modules
Four 4-channel, 12-bit ADCs
Temperature Sensor
Up to two Quadrature Decoders
Optional on-chip regulator
Up to two FlexCAN modules
Two Serial Communication Interfaces (SCIs)
Up to two Serial Peripheral Interfaces (SPIs)
Up to four general-purpose Quad Timers
Computer Operating Properly (COP) / Watchdog
JTAG/Enhanced On-Chip Emulation (OnCE™) for unobtrusive, real-time debugging
Up to 76 GPIO lines
160-pin LQFP Package and 160 MAPBGA

内核主要特性:
Efficient 16-bit 56800E family controller engine with dual Harvard architecture
Up to 60 Million Instructions Per Second (MIPS) at 60MHz core frequency
Single-cycle 16 × 16-bit parallel Multiplier-Accumulator (MAC)
Four 36-bit accumulators, including extension bits
Arithmetic and logic multi-bit shifter
Parallel instruction set with unique DSP addressing modes
Hardware DO and REP loops
Three internal address buses and one external address bus
Four internal data buses and one external data bus
Instruction set supports both DSP and controller functions
Controller-style addressing modes and instructions for compact code
Efficient C compiler and local variable support
Software subroutine and interrupt stack with depth limited only by memory
JTAG/EOnCE debug programming interface



图1.56F8367/56F8167 方框图
光伏电压逆变器
Photovoltaic system sizes range from small off-grid systems providing hundreds of watts to large central utility power plants generating over one megawatt. There is a wide range of PV system configurations and a wide range of inverters on the market, with some inverter manufacturers offering over 20 models. Because the PV industry is evolving so rapidly, inverter manufacturers must continually design new products. This requires scalable and flexible control systems, that allow design and software reuse.

Freescale 56F8000 DSC series solutions are ideal for photovoltaic inverter control, combining the processing power of a digital signal processor with the functions and ease of use of a microcontroller — in a true single chip solution. These solutions provide high integration at the right price to reduce overall PV inverter costs while helping to improve efficiency and reliability. Integrated peripherals include:

Dual 6-output pulse wave modulation modules
Four 12-bit analog-to-digital converters with more than 16 channel inputs
Up to 16 multi-function 16-bit timers
A variety of serial communication peripherals and on-chip voltage regulator
Power supervisor
Temperature qualified up to 125°C
Off-grid systems are used to drive local loads. They normally require a battery pack and battery charging/management system. They can provide both DC and AC output power but are not connected to the utility grid. Typical output power ranges from hundreds of watts to a few kilowatts and is single phase. Control solutions for these systems include the MC56F8013 and MC56F8036.
The 56F8013 is used on primary side to control Maximum Power Point and battery charging. The 8036 controls a boost stage and the DC/AC inverter stage.



图2.小于3KW离线光伏电压逆变器方框图
Residential scale grid-tie systems are the most common types of system today. They typically provide three to 10 kilowatts of output power and are not normally accompanied by a battery backup. Output AC power must be synchronized in phase, frequency, and voltage to the grid and have a low total harmonic distortion. String inverters, which control one or more strings of individual PV modules, are the most common types of inverters used for residential applications. Key requirements for these inverters are high efficiency and long lifetime as well as low cost. The 56F83xx series of DSCs provide single chip control solutions for both MPPT and DC/AC conversion.



图3. 1-10KW连接电网住宅区光伏电压逆变器方框图
Large commercial and central utility power generation systems are the fastest growing sector of the PV industry today Growth is spurred by continued reduction in the price of PV electricity and by favorable government policies, including feed-in tariffs, tax incentives and the requirement for utilities to provide a certain minimum percentage of their power from renewable sources. These systems can range from tens of kilowatts for commercial rooftop systems to over 100 megawatts for utility-scale central power generation plants occupying many acres of land.
The inverters for these systems are central inverters, although a parallel combination of several string inverters may also be used. In addition to supplying AC power to the grid, central inverters may also be used for power factor correction. One control solution for commercial inverters is to use a 56F8037 for DC/DC control and a member of the 56F83xx family for DC/AC inverter control. In addition, a Coldfire MCU can be used for supervisory control and communications.



图4. 大于10KVA连接电网商用光伏电压逆变器方框图