Three-Level SVPWM method with neutral-point balancing and common-mode voltage suppression capabilities

Abstract

The invention discloses a three-Level SVPWM method with neutral-point balancing and common-mode voltage suppression capabilities. The problem of unbalanced neutral point potential occurs when a three-phase T-type three-level inverter applied to a permanent magnet synchronous motor vector transformation control system adopts a single power supply scheme, which usually leads to performance reduction of the inverter. The three-Level SVPWM method aims to maintain neutral point balance of the three-level inverter under more complex working conditions without changing hardware structure and increasing size and cost of the inverter significantly through improving the traditional SVPWM method; the three-Level SVPWM method further improves the common-mode voltage suppression capability, reduces impact to motor insulation, prolongs the service life of the motor, reduces maintenance cost, and improves the operation stability of the motor control system; and the improved SVPWM method is suitable for digitization, and the calculation workload during the neutral point balance regulation process is small, thereby facilitating real-time control of a microcomputer system.

Description

technical field [0001] The invention relates to the technology of medium and low voltage frequency converters and the field of three-level inverters, in particular to a three-level SVPWM (space vector pulse width modulation) method with midpoint balance and common mode voltage suppression capability. Background technique [0002] The traditional two-level inverter is currently the most widely used inverter form in the field of motor control and transmission. It is the most popular due to its simple topology and simple control algorithm. However, with the increase of voltage level and capacity level, the shortcomings of two-level inverters are becoming more and more prominent. The quality is not high, so people began to look for new topological forms, and the three-level inverter came into being. Compared with the traditional two-level inverter, the three-level inverter has the advantages of small harmonic components, low requirements on the withstand voltage of the device, ...

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Problems solved by technology

Voltage space vector modulation is widely used in microcomputer control systems because of its ease of digitization and simple control. However, there are usually the following problems in the process of use: first, the inherent midpoint potential balance problem of the three-level inverter topology, and second, the common-mode voltage overshoot. Big problem, the first problem will lead to the increase of the harmonic component of the output power of the inverter and the deterioration of the power quality, which may affect the operation of the inverter in severe cases; the second problem will test the insulation of the motor, if the insulation level Not enough, then once the ordinary voltage space vector modulation is used, it may cause a series of insulation problems, and the life and stability of the motor will be greatly reduced

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