Three-level ANPC (active neutral-point-clamped) convertor neutral-point voltage balance control method

A control method and voltage balancing technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve problems such as midpoint voltage fluctuations, three-phase output asymmetry, and loss of practical significance

Active Publication Date: 2017-05-31
ANHUI UNIVERSITY
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  • Application Information

AI Technical Summary

Problems solved by technology

One of the prerequisites for the normal operation of three-level and above ANPC topologies is that the midpoint voltage must be balanced. During SVPWM control, if the key issue of midpoint voltage balance is not considered, the midpoint voltage will be relatively large during...

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  • Three-level ANPC (active neutral-point-clamped) convertor neutral-point voltage balance control method
  • Three-level ANPC (active neutral-point-clamped) convertor neutral-point voltage balance control method
  • Three-level ANPC (active neutral-point-clamped) convertor neutral-point voltage balance control method

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Embodiment Construction

[0021] SVPWM is based on the ideal flux circle of the stator of the three-phase symmetrical motor when the three-phase symmetrical sine wave voltage is supplied as the reference standard, and the different switching modes of the three-phase converter are used for appropriate switching to form a PWM wave, and the actual flux vector formed is to track the reference flux circle. The traditional SPWM method starts from the point of view of the power supply to generate a sine wave power supply with adjustable frequency and voltage, while the SVPWM method considers the inverter system and the asynchronous motor as a whole. The model is relatively simple, and it is also convenient for the real-time control. SVPWM control is selected, and only one device is involved in each switching, so the switching loss is small; the three-phase PWM wave is directly generated by using the voltage space vector, and the calculation is simple; the voltage utilization rate is higher than that of the tr...

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Abstract

The invention relates to a three-level ANPC convertor neutral-point voltage balance control method. The method comprises the following steps of (1) acting on a three-level ANPC convertor through an SVPWM (space vector pulse width modulation) pulse sequence; (2) detecting the voltage of the direct current side capacitor of the convertor in real time to obtain a neutral-point voltage, and comparing the neutral-point voltage with a reference neutral-point voltage to determine whether the direct current side capacitor requires charging or discharging; (3) in real time detecting the positive and negative direction of the three-phase load current of the convertor; (4) integrating detecting values of the steps (2) and (3), within every switching period, dynamically adjust the duty ratio of the zero state of the switch sequence of a three-phase bridge arm until neutral-point voltage balance, and repeating the step to maintain fluctuation of the neutral-point voltage within a relatively small range. The three-level ANPC convertor neutral-point voltage balance control method can dynamically adjust the charging and discharging time of the capacitor according to the direction of the three-phase load current and the size of the neutral-point voltage to rapidly balance of the neutral-point voltage and to maintain fluctuation of the neutral-point voltage within a relatively small range.

Description

technical field [0001] The invention relates to a control strategy of a three-level converter, in particular to a midpoint voltage balance control method of a three-level ANPC converter. Background technique [0002] With the advancement of technology and the improvement of living standards, people's requirements for power quality are also constantly improving. The emergence of active neutral-point-clamped (ANPC) topology makes up for the diode-clamped topology and capacitor The shortcomings of the clamping topology are better suited for 6KV and 10kV high-voltage frequency conversion fields. ANPC multi-level converters are increasingly being used in fields such as industry and social life to provide better quality electric energy. At present, although it is common to use the SVPWM modulation method to act on the three-level ANPC converter at home and abroad, the method of controlling the midpoint voltage balance when using the SVPWM modulation method to act on the three-lev...

Claims

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Application Information

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IPC IPC(8): H02M7/487
CPCH02M7/487
Inventor 胡存刚马大俊王群京李国丽
Owner ANHUI UNIVERSITY
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