Abstract : To improve the grid voltage compensation effect, starting from the main circuit topology and based on the low-voltage inverter regular sampling method, this paper details the theoretical analysis and algorithm derivation process suitable for multilevel inverter control. A multilevel inverter control method based on grid voltage compensation is proposed, and the sampling principle and timing suitable for digital signal processing are given. The output voltage is adjusted in real time according to the grid voltage change to obtain the same ideal mechanical characteristics and operating effect as the closed-loop system. This method features simple calculation steps, good output SPWM symmetry, high accuracy, and convenient control, and is applicable to any number of levels and topology. Experimental results show that it has better performance and high utilization value compared with other multilevel control methods. Keywords : Grid voltage compensation; Multilevel inverter; Sampling; SPWM ZHANG M in (1. College of Automation, Qingdao Technological University Qingdao, 266033; 2. Xi'An University of Science and Technology, Xi'An 710054, China)[/align][/b] Abstract: In order to improve the compensation effect of power network voltage, a new method for multilevel converters based on the compensation of power network voltagO is proposed. The article begins with the structure of main-loop and takes the regular sample theorem of low-voltage converter as the basic theory． Then it introduces the theoretical analysis and algorithm deducing process in detail which is propitious to multilevel converter control1． Sample theorem and sample time which are applied in digital process are also proposed． In order to acquire ideal mechanical character and running performance as closed loop, it regulates output voltage at times according to the variety of the voltage of power network． The method not only has great advantages such as simple calculation, high precision in the symmetry of SPW M output wave, high precision and convenience in control, but it is also applicable for any number of levels and structures. The results show that it has practical value for multilevel converter compared with other methods. Key words : compensation of power network voltage; multilevel converter; sample; SPWM 0 Introduction In recent years, multilevel frequency converters have been increasingly widely used in high-voltage, high-power frequency converters. Its basic topology is three forms: diode clamping, flying capacitor, and multilevel series. In comparison, the multilevel series type has the following advantages: (1) It adopts the power unit series connection instead of the power device series connection scheme, which saves a lot of clamping diodes and voltage balancing capacitors in the circuit; each power unit adopts a modular structure, which is interchangeable and easy to maintain. (2) The inverter structure is based on the traditional two-level inverter unit form, and the main circuit topology is very simple. (3) Each inverter bridge is powered by an independent DC voltage source, and there is no problem of neutral point voltage imbalance. These types of frequency converters mostly adopt open-loop control schemes. Fluctuations in the grid voltage directly affect the output voltage, which in turn affects the motor's output power. If the output voltage can be adjusted in real time according to changes in the grid voltage without affecting the system structure, ideal mechanical characteristics and operating effects similar to those of a closed-loop system can be directly obtained. [b]1 Multi-unit Series High-Power Inverter Principle 1.1 Main Circuit Topology[/b] [b][align=center]For details, please click: Multi-level Frequency Converter Control Based on Grid Voltage Compensation[/align][/b]