A zero-vector starting svpwm midpoint potential balance control method

Abstract

A zero vector starting SVPWM neutral point potential balance control method is provided. When the midpoint potential oscillation exceeds a limited value, the control method firstly compares the actiontimes of two small vectors in the current sampling period of the zero vector start SVPWM, defines a small vector with a longer action time as a long small vector, and defines a small vector with a shorter action time as a short small vector; A time allocation factor ptime is obtained by detecting the neutral point current direction and the neutral point potential oscillation value corresponding to the long small vector and sending the oscillation value to the PI controller. The neutral point potential balance of zero vector initiation SVPWM method is dynamically adjusted by using the time allocation factor ptime to control the action time of long and small vectors. The control method of the invention can control the neutral point potential deviation under the action of the zero vector start SVPWM method in a relatively small range, and overcomes the shortcoming that the traditional zero vector start SVPWM method can not balance the neutral point potential by using redundant small vectors. The neutral point potential deviation of the zero vector start SVPWM method is controlled in a relatively small range.

Description

technical field [0001] The invention relates to a midpoint potential balance control method, in particular to a zero vector initial SVPWM midpoint potential balance control method. Background technique [0002] The topology of the three-level NPC (Neutral Point Clamped) inverter is as follows: figure 1 As shown, compared with the two-level topology, the three-level NPC inverter can output three different level states by controlling the on and off of each switching device of the three-phase bridge arm, and each switching device bears Less voltage stress allows doubling the output voltage. In addition, the structure of the three-level NPC inverter is simple, and it is easy to realize the bidirectional flow of energy by adopting the back-to-back structure. Based on the above advantages, the three-level NPC inverter is currently widely used in the regulation speed occasions. [0003] The SVPWM (Space Vector Pulse Width Modulation) method is the space vector pulse width modula...

AI Technical Summary

Problems solved by technology

[0012] In order to overcome the shortcoming that the traditional zero-vector initial SVPWM method cannot use redundant small vectors to carry out mid-point potential balance control, the present invention proposes a zero-vector initial SVPWM mid-point potential balance control method

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