Jul 29, 2020
EPS emergency power system mainly includes rectifier charger, battery pack, sine wave inverter, mutual input device and system controller. Among them, the inverter is the core. Usually, DSP or single-chip CPU is used to control the inverter part by SPWM modulation to obtain a good AC waveform output; the role of the rectifier charger is to realize the timing of the battery pack when the mains input is normal. Charging; the role of the inverter is to convert the DC energy stored in the battery pack into AC output when the mains is abnormal, and supply the load equipment with stable and continuous power; the mutual input device ensures that the load is between the mains and the inverter output The system controller performs real-time control of the entire system, and can send fault alarm signals and receive remote linkage control signals, and can realize remote monitoring of the EPS system by the host computer through the standard communication interface.
A sine wave inverter is a power electronic device that converts direct current (power battery, storage battery) into alternating current (generally 220V, 50Hz sine wave). Inverter and ACDC converter are opposite processes. ACDC converter or power adapter is usually used to rectify 220V alternating current into direct current for use, and the inverter has the opposite effect, hence the name.
The development of sine wave inverter technology has always been closely integrated with the development of power devices and their control technology. It has gone through five stages since its inception.
The first stage: From the 1950s to the 1960s, the birth of thyristor (SCR) created conditions for the development of sine wave inverters;
The second stage: In the 1970s, the emergence of turn-off thyristors (GTO) and bipolar transistors led to the development and application of inverter technology;
The third stage: In the 1980s, the advent of power FETs, insulated gate FETs and MOS controlled intertransistors laid the foundation for the development of high-power inverters;
The fourth stage: In the 1990s, the development of microelectronics technology enabled new control technologies such as vector control technology, multi-level control technology, fuzzy control technology and repetitive control technology to be better applied in the field of inverters. Greatly promote the development of inverter technology;
The fifth stage: At the beginning of the 21st century, with the continuous progress and improvement of power electronic technology, modern control theory and microelectronics technology, inverter technology is moving towards high efficiency, high frequency, high reliability, high power density and intelligence. The direction of development.
The development trend of sine wave inverter
With the rapid development of power electronics technology and the improvement of inverter control performance requirements in various industries, sine wave inverters have also been rapidly developed. The current development directions of inverters are mainly:
High frequency refers to increasing the operating frequency of power switching devices, which can not only reduce the volume of the entire system, but also has a good suppression effect on audio noise, while improving the dynamic response capability of the inverter output voltage. The high-frequency power switching device corresponds to the high-frequency isolation transformer, and the application of the high-frequency isolation transformer has further reduced the volume of the entire system.
The effective value is the main parameter of the inverter's output voltage. The high-performance inverter has a stable effective value of output voltage, and at the same time has a high waveform quality, and has a strong ability to adapt to non-linear loads. Because the load carried by the inverter will change suddenly in many cases, high-performance inverters require high transient response performance in the output voltage. Another important parameter for AC output voltage is frequency. A good inverter requires not only a stable RMS value of the output voltage, but also a stable frequency. Only the inverter with the above characteristics can be called a high-performance inverter.
The current inverter technology can produce high-power products, but once the inverter system fails in high-power applications, the system will be paralyzed. In a system composed of low-power inverters through parallel technology, the normal operation of each unit does not affect the operation of other units, which greatly improves the reliability of the entire system.
Miniaturization corresponds to the result of high frequency, because the main method to miniaturize the inverter is to increase the operating frequency of the switching tube and use a high frequency transformer. Another method is to improve the control method and optimize the frequency spectrum of the SPWM wave to reduce the filter volume.
High input power factor
Many inverter systems use certain topological circuits to convert DC power into high-frequency AC pulses, and then rectify them to obtain the required DC voltage. The sharp peaks in the output current reduce the input power factor, and increase the input side power factor can effectively solve the harmonic pollution of the inverter to the grid.
Intelligent and digital
The digitization of the inverter is not simply the application of digital devices such as FPGA and single-chip microcomputer in the inverter, but the entire system depends on the computing power of digital devices and discrete control methods. With the development of hardware, the processor speed is getting higher and higher, prompting the inverter to develop towards the direction of intelligence and digitization.
Advantages of sine wave inverter
Pure sine wave output, suitable for TV, refrigerator, induction cooker, electric fan.
Household appliances such as microwave ovens and air conditioners use # microcomputer (CPU) control technology with superior performance.
Ultra-wide input voltage range, high-precision output, fully automatic voltage stabilization.
Built-in protection functions such as overload, short circuit, over voltage, under voltage, over temperature, etc., with high reliability.
The concise and clear LED display can be upgraded to a comprehensive digital LCD display for easy observation of the machine status.
The power supply time can be arbitrarily configured according to different requirements.
Adopt valve-regulated maintenance-free lead-acid battery, intelligent battery management, overcharge and overdischarge protection, extend battery life.