With the development of my country's national economy and the continuous improvement of people's material cultural living, air conditioners have been widely used in society, and the inverter air conditioners have energy saving, low noise, constant temperature control, all-weather operation, start low-frequency compensation, fast To achieve performance and other performance, the comfort of the air conditioner is greatly improved, and it will be more and more love. The widespread application of single-chip technology, frequency conversion technology and fuzzy control technology successfully applied in the field of air conditioner embedded control, the rapid development of semiconductor power devices provides technical guarantee for the promotion of frequency conversion control.
The AC variable-conversion air conditioner controller of this design is composed of two parts: indoor unit controllers and outdoor controllers. Based on the superior performance of the SPMC75F2413A, it is easy to implement the product modularity, intelligent characteristics, and the control parameters, which can be coupled to a variety of compressors, which can be coupled to various compressors.
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The upgrade of the product with the requirements of the manufacturer. In this way, the product can push the market faster to the market and get the time competitive advantage. This controller contains the following key technologies:
1. Fuzzy control technology: According to the indoor ring temperature, tube temperature, outdoor ring temperature, tube temperature, compressor exhaust temperature, compressor overload protection temperature, compressor current and other parameters, control the operation speed of the compressor , Outdoor fan and other load operation;
2. Efficient three harmonics injection into DDS-based SPWM technology, make full use of power supply voltage, accurate frequency adjustment, real-time voltage replenishment, make compressors more effectively;
3, module control protection circuit: When the module has a protection signal output, the control signal is disconnected by the hardware circuit, to achieve the effect of the protection module, and reliably protect the signal;
4, EMC and Reliability Design Technology: Under the premise of mastering the interference mechanism of air conditioners, hardware design focuses on the following points: power circuit design, filter circuit parameter design, printed board floor and signal line design, and software is fault tolerant Technology. Be
2 chip characteristics
The system is an AC variable frequency air conditioning scheme implemented based on intelligent power module chip PS21865A and SPMC75F2413A, which describes the characteristics of SPMC75F2413A.
SPMC75F2413A is a new member of the μnsp series product, which is a new 16-bit structure of Lingyang Technology. Unlike other μnSP? Products, SPMC75F2413A is mainly used in the field of power control or home appliances. Because it has an excellent performance timer PWM signal generator group. Therefore, the SPMC75F2413A can easily implement various motor drive schemes.
The SPMC75F2413A has a working speed range of 4.5V to 5.5V in the operating speed range of 0 to 24 MHz, with 2k word SRAM and 32K word flash ROM; 64 programmable multi-function I / O ports; 5 universal 16-bit timer / Counters, and each timer has an event capture function that occurs in PWM; 2 dedicated to timing programmable cycle timers; programmable watchdog; low voltage reset / monitoring function; 8-channel 10-position-digital conversion. The SPMC75F2413A has a considerable performance in the field of frequency conversion control.
Features include:
. Lingyang 16 μ'nsp? Processor (ISA 1.2)
. Operating Voltage:
- Nuclear: 4.5V ~ 5.5V
. Maximum running speed: 24MHz
. Work temperature: -40 ° C ~ 85 ° C
. Chip memory:
- 32KW (32k × 16) Flash
- 2KW (2k × 16) SRAM
. Locking ring circuit based on clock generation module
. Watchdog timer
. 10-digit / digital converter
- 8 channel input
10US (100kHz) conversion time
. Serial communication interface
- Universal Asynchronous Serial Communication Interface (UART)
- Standard synchronous serial port (SPI)
. Total 64 universal input output pins
. Power management
- 2 low power modes: Wait / Standby
- Each peripheral can power
. Two compare match timers
. 5 16-bit universal timer
. 2 for pulse width modulation, 2 for speed capture, 1 for speed feedback loops.
. MCP Timer 3 supports TiO3a ~ TiO3F, MCP Timer 4 supports TiO4a ~ TiO4F
. Pulse width adjustment timer supports increment / decrement count
. PDC Timer 0/1 supports 3 channels of TiO0a ~ TiO0c input capture
. TPM timer 2 supports capture / pulse width modulation
. 12 16-bit pulse width modulation output
. 2-channel motor drive pulse width modulation output (complementary 3-phase 6-way pulse width modulation output)
. TiO3a ~ TiO3F uses MCP timer 3 to work, TiO4a ~ TiO4f works with MCP timer 4
. Center (Center) or edge (EDGE) pulse width modulation output
. Pulse width modulation output protection via external error protection tube foot
. Programmable dead zone control (DEAD TIME Control)
. Pulse width modulation service and error interruption occurrence
. Ability to drive an AC induction motor and DC brushless motor
. Inline online simulation function
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3 system overall plan introduction
This AC variable frequency air conditioner system is divided into two parts: indoor unit system and outdoor unit system, wherein the indoor unit system is mainly processing some logical status information, and the outdoor unit system is mainly a variable frequency drive portion of the compressor. The indoor units are achieved in this system scheme, and the SPMC75F2413A is mainly applied to the variable frequency drive portion. Therefore, the indoor unit system will not be detailed herein. The circuit structure block diagram of the outdoor unit is shown in Figure 3-1.
Figure -1 outdoor unit system block diagram
The basic workflow of this system:
The main control MCU (SPMC75F2413A) of the outdoor unit receives control and status information from the indoor unit, thereby dealing with the wind turbine, four-way valve, and compressor to complete the corresponding control function. At the same time, some of the states of the outdoor unit and some temperature information of the outdoor. Use the indoor machine to do control. Be
4 system hardware design
The system circuit schematic is shown in Figure 4-1. Where the PS21865A three-phase power full bridge circuit module is used to implement the power synthesis of the PWM signal, thereby drive the compressor. The ULN2003A is a power reverse of the collector open circuit, mainly used to drive relays in the system to control fan and solenoid valves. The main role of the SPMC75F2413A microcontroller: 1. Control the entire system according to the indoor unit command. 2. Complete the generation and control function of the variable frequency drive signal of the AC variable frequency compressor.
Power_LINE in Figure 4-1 is a half-duplex current loop transform circuit, which mainly utilizes a power source and a dedicated communication line to make indoor and outdoor, and the current ring is powered by the indoor unit. This circuit provides a communication loop for indoor and outdoor machines. The SPMC75F2413A synthesized SPWM signal is output by IOB0 to 5, and the PS21865A is input after the buffer and the light, and the post-output control motor is output. The IOB6 of the SPMC75F2413A is an error detection input. By detecting its backup signal, once the PS21865A operates anomalies (such as overwhelming, undervoltage, over-flow, overheating), the drive hardware will prohibit PS21865A work, and apply for interruption. Request CPU processing. IOA0 ~ 3 is an analog input port, mainly temperature sensor interface and DC high-pressure measurement interface. IOC8 ~ 10 is the control of the four-way valve and outer fan.
Figure 4-1 System Circuit Schematic
5 system software design
The entire outdoor system software mainly includes the following parts: 1. Communication with indoor units, coordinate the control section. 2. The compressor drive control section of the outdoor unit.
The system is communicated with indoor units, and the coordination control section mainly includes serial port interrupt service and command interpretation execution and primary loop control. The main control process is shown in Figure 5-1. The serial interrupt service is mainly to receive packets from the indoor unit, and process the corresponding information to ensure the correctness of the command and data of the control program; the command interpretation execution section mainly interprets the indoor unit command, and performs corresponding processing .
Figure 5-1 Mainflow
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The compressor drive control section is divided into SPWM signal synthesis, motor plus deceleration control, and a start-stop service of the motor. The core of which is the synthesis of the SPWM signal. The waveform synthesis of the system is performed using DDS (direct digital frequency synthesis). This part is mainly composed of a PWM periodic table interrupt service and a corresponding auxiliary calculation program. Where PWM cycle interrupt service is a core part of signal synthesis, which occupies an amount of calculation of about 70% in the entire system. It mainly completes the dynamic replenishment function of the synthesis and trunk voltage of the drive waveform, while the cycle interrupts for DDS to provide clock reference reference; and the acceleration and deceleration control portion mainly tracks the setup frequency, so that the current operating frequency is approximated to the target operating frequency to the target operating frequency. The start-stop service of the motor is primarily handled for motor launch and stops these two special processes.
Since the PWM period interrupt service program performs high (about 5kHz), this part uses compilation to write to ensure that as small as possible CPU resource is occupied. The process of the PWM interrupt service subroutine is shown in Figure 5-2.
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Figure 5-2 PWM interrupt service subroutine flow chart
6 conclusion
Typically, in the process of developing a frequency conversion device, it is necessary to write code real-time, program readability, and mixed programming is required. And Lingyang's M'NSP? IDE has a good programming environment, which can be easily and easy to make mix programming (call assembler in the C program, call C procedures in the assembler).
The system uses two timers of SPMC75F2413A and about 17 IO resources, in fact, the resources of SPMC75F2413A are quite rich. Because of its professional frequency conversion hardware support, the development of frequency conversion system is relatively simple. At the same time, the SPMC75F2413A has a quite average performance in frequency conversion control. Therefore, the frequency conversion system based on the SPMC75F2413A has broad application prospects in the field of universal frequency conversion, frequency conversion home appliances.
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Reprinted from -Wiku Electronic Market Network
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