A Space Vector Modulation Method with Neutral Potential Balance Control

Abstract

The invention provides a space vector modulation method having the mid-point potential balance control function and belongs to the space vector modulation method. According to the method, firstly, a conventional virtual space vector is modified, wherein a regulatory factor is respectively introduced into a virtual small vector and a virtual middle vector. After that, in order to overcome the defect that the DC unbalance of the point potential of a virtual space vector in a three-level current transformer cannot be self-recovered in the prior art, a model prediction-based multi-objective optimization DC unbalance control policy is added in the conventional modulation policy, so that the point potential of the virtual space vector in the three-level current transformer can be completely controlled. Based on the above improved virtual space vector modulation method, the DC unbalance defect of the mid-point potential of a conventional virtual space vector in the prior art can be overcome. Based on the additionally adopted multi-objective optimization control policy, the conflict between the recovery speed and the quality during the DC imbalance recovery process can be well solved. At the same time, the low-frequency oscillation phenomenon of the improved virtual space vector at the mid-point potential thereof can be eliminated as well as that of a traditional virtual space vector.

Description

technical field [0001] The invention relates to a space vector modulation method, in particular to a space vector modulation method with neutral point potential balance control. Background technique [0002] Pulse Width Modulation (PWM) is the core technology in the field of inverter control, and the quality of the modulation strategy will directly affect the various performance indicators of the inverter. The existing pulse width modulation techniques can be roughly divided into two categories: one is the modulation strategy based on carrier comparison (CB-PWM), and the other is the modulation strategy based on space vector synthesis (SVM). The two types of modulation strategies have distinct advantages and disadvantages. The carrier-based modulation technology algorithm is simple and has less hardware resource overhead, but its DC bus voltage utilization rate is low and the voltage distortion rate of the AC output terminal is high; while the space vector-based modulation t...

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Problems solved by technology

However, the virtual space vector guarantees that the average midpoint potential is zero during each vector action time. When the midpoint potential is unbalanced due to some reasons, the virtual space vector modulation technology will not be able to restore the midpoint potential DC imbalance by itself.

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