Abstract: This paper mainly introduces the control scheme of DC inverter air conditioner using SPMC75F2413A single chip microcomputer. The working mechanism of DC inverter air conditioner controller, focusing on the use of SPMC75F2413A in DC inverter air conditioner.
Keywords: SPMC75F2413A, PS21865A, fuzzy control, Lingyang MCU,
1 Introduction <br> With the development of China's national economy and the continuous improvement of people's material and cultural living standards, air conditioners have been widely used in various occasions of society. DC inverter air conditioners are energy-saving, low-noise, constant-temperature control, and all-weather operation. The ability to start low-frequency compensation and quickly reach the set temperature makes the comfort of the air conditioner greatly improved, and will be more and more popular. The wide application of single-chip technology, DC inverter technology and fuzzy control technology in the field of embedded control of air conditioners, the rapid development of semiconductor power devices provides technical support for the promotion of DC inverter control.
The DC inverter air conditioner controller of this design consists of two parts: an indoor unit controller and an outdoor unit controller. Based on the superior performance of SPMC75F2413A, it is easy to realize the modularization and intelligent features of the outdoor DC inverter controller. The control parameters are open structure, which is easy to connect with various compressors, so that it can be different in the shortest time. The manufacturer's requirements for product upgrades. In this way, products can be brought to market faster and gain a competitive advantage over time. This controller contains the following key technologies:
1. Fuzzy control technology: According to indoor ring temperature, tube temperature, outdoor ring temperature, tube temperature, compressor discharge temperature, compressor overload protection temperature, compressor current and other parameters to establish fuzzy logic relationship, control compressor operating speed , outdoor fans and other loads are running;
2. BLDC drive technology based on back EMF position detection;
3. Module control protection circuit: When the module has protection signal output, the PWM module outputs the control signal through the hardware circuit to achieve the effect of the protection module, and reliably protect the signal to the MCU module;
4. EMC and reliability design technology: Under the premise of mastering the interference mechanism of air conditioner, the hardware design focuses on the following points: power circuit design, filter circuit parameter design, printed circuit board ground and signal line design, and software adopts fault tolerance. technology.
2 Introduction to chip characteristics <br> This system is based on intelligent power module chip and SPMC75F2413A to achieve DC inverter solution. The following describes the characteristics of SPMC75F2413A.
The SPMC75F2413A is a new member of the μ'nSP? series and is a new 16-bit microcontroller from Sunplus Technology. Unlike other μ'nSP products, the SPMC75F2413A is mainly used in the field of variable frequency drives for industrial control or home appliances. Thanks to its excellent performance timer PWM signal generator set. Therefore, the SPMC75F2413A can easily implement various motor drive schemes.
The SPMC75F2413A operates from a 12V to 5.5V operating voltage range of 12 to 24MHz, with 2K words of SRAM and 32K words of flash ROM; 64 programmable multifunction I/O ports; and 5 general purpose 16-bit timers. Counter, and each timer has an event capture function for PWM generation; 2 dedicated to the timer programmable cycle timer; programmable watchdog; low voltage reset/monitor function; 8-channel 10-bit analog-to-digital conversion. The SPMC75F2413A has a very good performance in the field of motor control.
Features include:
◆ Lingyang 16-bit μ'nSP? processor (ISA 1.2)
â—† Working voltage:
Core: 4.5V ~ 5.5V
â—† Maximum operating speed: 24MHz
◆ Operating temperature: -40 °C ~ 85 °C
â—† On-chip memory:
32KW (32K×16) Flash
2KW (2K×16) SRAM
â—† Phase-locked loop circuit based on clock generation module â—† Watchdog timer â—† 10-bit A/D converter 8-channel input 10us (100kHz) conversion time â—† Serial communication interface Universal asynchronous serial communication interface (UART)
Standard peripheral interface (SPI)
â—† A total of 64 general purpose input and output pins â—† Power Management 2 low power modes: Wait/Standby
Each peripheral can be powered independently â—† Two compare match timers â—† Five 16-bit general-purpose timers 2 for pulse width modulation 2 for speed capture 1 for speed feedback loop.
â—† Center or edge pulse width modulation output â—† Pulse width modulation output protection through external error protection pin â—† Programmable dead time control (Dead time control)
â—† Pulse width modulation service and error interrupt generation â—† Ability to drive AC induction motor and DC brushless motor â—† Embedded online simulation function
3 System overall program introduction <br> The DC inverter air conditioner system is divided into two parts: indoor unit system and outdoor unit system. The indoor unit system is mainly the processing of some logic state information of the system, and the outdoor unit system is mainly the variable frequency drive of DC compressor. section. In the system scheme, the indoor unit is selected by SPMC701FM0A, and the SPMC75F2413A is mainly applied to the BLDC variable frequency drive part. The system block diagram is shown in Figure 3-1.
Figure 3-1 DC inverter air conditioner system block diagram
The basic working process of the system:
The outdoor unit's master MCU (SPMC75F2413A) receives control and status information from the indoor unit at any time to control the outdoor fan, four-way valve and compressor to complete the corresponding control functions. At the same time, some status of the outdoor unit and some outdoor temperature information will be transmitted back to the indoor unit. The indoor unit coordinates the entire air conditioning system according to the parameters returned by the outdoor unit and some working status and temperature information of the indoor unit itself.
4 system hardware design
The whole system consists of two parts: the indoor unit system and the outdoor unit system. The following mainly introduces the indoor system.
4.1 System Structure <br> The outdoor unit system is mainly composed of IPM power drive module, back EMF position detection circuit, switching power supply, outdoor fan drive, MCU subsystem composed of SPMC75F2413A and Power Line communication circuit. The circuit structure of the outdoor unit system is shown in Figure 4-1.
Figure 4-1 Block diagram of the outdoor unit system
4.2 MCU Control Circuit <br> Figure 4-2 shows the MCU control circuit. The circuit in this part is mainly based on SPMC75F2413A microcontroller. CON5 is connected to online debugging and emulator ICE. The MCU control circuit is the control core of the entire outdoor unit system, and all peripherals of the outdoor unit operate under their coordinated control.
Figure 4-2 MCU control circuit
4.3 Power Circuit <br> Figure 4-3 shows the EMI power supply filter circuit and soft start circuit. The AC power input connectors are CON1, CON3 and CON5, the voltage is 220VAC, and the power input terminal passes the surge absorber ZNR3 to avoid excessive voltage. The surge damages the device, L1, C2, C1, C5 and C3 form an EMI filter circuit to filter out electromagnetic interference in the circuit; RL1, RT2 and D1 form a soft start circuit to prevent large current surge when the circuit is powered.
Figure 4-3 EMI Power Filter
Figure 4-4 shows the DC/DC power supply circuit. The circuit consists of the TOP234 and its corresponding peripheral circuits. The circuit's output P+18V and +12V power supply are used by the system. After the P+18V power supply is output, P+15V and P+5V are generated through IC21 and IC22 respectively to supply the working voltage of the IPM power module. The +12V is supplied with a +5V power supply to the digital circuit such as the SPMC75F2413A via the linear regulator IC20.
Figure 4-4 DC/DC power supply circuit
4.4 Outdoor fan drive circuit
The outdoor fan uses a BLDC with a Hall sensor, and its drive circuit is shown in Figure 4-5. The circuit is implemented using the SMA5118 and the power driven diaphragm TLP251. The SPMC75F2413A output PWM signal is optically isolated by TLP251 and sent to the SMA5118 power driver module for power synthesis and output, thus driving the fan to work reliably.
Figure 4-5 Outdoor fan drive circuit
4.5 compressor power drive circuit
The compressor power drive circuit is shown in Figure 4-6. The circuit is mainly composed of an IPM power drive module (PS21865A) circuit and a PWM signal photoelectric isolation drive circuit. The SPMC75F2413A output PWM signal is photoelectrically isolated and sent to the IPM power drive module for power synthesis and output, thereby driving the compressor.
Figure 4-6 IPM motor drive circuit
4.6 Back EMF Position Detection Circuit <br> The back EMF position detection circuit is shown in Figure 4-7. The circuit mainly uses the BLDC motor to generate the back EMF characteristic of the rotor position on the stator coil when rotating. The circuit is composed of a voltage comparator and a corresponding RC network to complete the rotor position detection function of the sensorless BLDC motor.
Figure 4-7 Back EMF Position Detection Circuit
4.7 Power Line Communication Circuit The Power Line communication circuit is shown in Figure 4-8 and Figure 4-9. It is essentially a half-duplex current loop communication circuit. It mainly uses a power line and a dedicated communication line to form a current loop inside and outside the room, and the current loop is powered by the indoor unit. This circuit uses the UART communication module inside the chip to provide a reliable communication loop for indoor and outdoor units.
Figure 4-8 Power Line communication circuit indoor unit
Figure 4-9 Power Line Communication Circuit Outdoor Unit
5 System Software Design The entire outdoor unit system software mainly includes the following parts:
1. Communicate and coordinate control with the indoor unit;
2. The compressor drive control part of the outdoor unit;
3. Outdoor fan drive control;
4. Four-way valve drive control.
The system communicates with the indoor unit, and the coordination control part mainly includes serial port interrupt service, command interpretation execution and main loop control. The main control flow is shown in Figure 5-1. The serial port interrupt service mainly receives data packets from the indoor unit and processes the corresponding information to ensure the correctness of the commands and data transmitted to the control program. The command interpretation execution part mainly interprets the indoor unit commands and performs corresponding processing. .
Figure 5-1 Main process
The compressor drive control part is divided into several parts such as BLDC core drive, motor acceleration/deceleration control, and motor start-stop service. The core of these is the BLDC core driver.
The SPMC75F2413A is a motor-specific IC. There are two sets of identical inverter motor drive hardware inside. It can drive two BLDC motors at the same time. This provides great convenience for the realization of DC inverter air conditioner. Therefore, the software part of the compressor drive becomes relatively simple, and it is only necessary to use the back position position detection circuit (as shown in Fig. 4-7) to provide the rotor position information for the drive circuit to conveniently drive the compressor. At the same time, the SPMC75F2413A also integrates a dedicated drive protection circuit to provide a complete protection function for the compressor and its drive circuit.
The outdoor fan of the DC inverter air conditioner uses the same BLDC motor as the compressor. Therefore, the drive software and the compressor drive section use the same structure.
6 Conclusion <br> Generally, in the process of developing frequency conversion equipment, it is necessary to write real-time, program-readable code, and then you need to use mixed programming. And Sunplus' u'nSP IDE has a good programming environment, it can be easily and easily mixed programming (call the assembler in the C program, call the C program in the assembler).
The system uses two timers of SPMC75F2413A and about 17 IO ports. In fact, the resources of SPMC75F2413A are quite abundant. Due to its professional frequency conversion hardware support, the development of frequency conversion systems has become relatively simple. At the same time, SPMC75F2413A has quite outstanding performance in frequency conversion control. Therefore, the frequency conversion system based on SPMC75F2413A has broad application prospects in the field of frequency conversion such as general frequency conversion and frequency conversion home appliances.
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