Control method for power balance of hybrid multilevel inverter

A hybrid multi-level, control method technology, applied in the output power conversion device, the irreversible DC power input is converted into the AC power output, the AC power input is converted into the DC power output, etc. Capacitor voltage fluctuation, complex control, etc.

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A hybrid multi-level, control method technology, applied in the output power conversion device, the irreversible DC power input is converted into the AC power output, the AC power input is converted into the DC power output, etc. Capacitor voltage fluctuation, complex control, etc.

CN104038092AActive Publication Date: 2014-09-10ZHEJIANG UNIV OF TECH

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Embodiment 1

[0033] Such as figure 1 As shown, the hybrid multilevel inverter in this embodiment is formed by cascading two full-bridge inverter units H1 and H2 and a diode-clamped inverter unit sequentially, and the output voltage of each unit synthesizes the phase output voltage. Under the traditional control strategy, within the full modulation ratio range, the high-voltage unit uses a fixed-value comparison level to output a composite voltage. However, when the modulation ratio is low, the high-voltage unit outputs zero voltage, resulting in extreme output voltage distribution and unbalanced output power distribution, which affects the reliability of the system.

[0034] In this embodiment, a non-fixed comparison level is used for the high-voltage unit within the full modulation ratio. When the modulation ratio is low, the high-voltage unit can still output an effective voltage, so that the power of each power unit maintains a balanced power output within the range of the full modulati...

Embodiment 2

[0050] In this embodiment, the hybrid multilevel inverter is formed by cascading a full-bridge inverter unit and a diode-clamped inverter unit, such as figure 2 shown.

[0051] The control method for the power balance of the inverter is generally consistent with that of Embodiment 1, wherein the calculation method of the comparison level of the full-bridge inverter unit is as follows:

[0052] λ = 4 V π sin ( arccos ψ m ( V + V D ) ) m ( ...

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Abstract

The invention discloses a control method for power balance of a hybrid multilevel inverter. The control method for the power balance of the hybrid multilevel inverter includes that confirming the maximum power output of each unit of the hybrid multilevel inverter through analyzing the output power of each unit, and confirming a comparative level of a high-voltage unit in a complete modulation ratio range according to a power output linear ratio of each unit, wherein the selection for the comparative level of the high-voltage unit and the linear control for the output power realize to balance the power through the special linear ratio of the output power. The control method for the power balance of the hybrid multilevel inverter avoids the phenomenons that when the modulation ratio is low, the high-voltage unit outputs zero voltage, the output power distribution of each unit appears an extreme state, the unit load output proportion gets out of control, and the system cannot work stably; the control method is simple and has higher reliability.

Description

technical field [0001] The invention belongs to the technical field of inverter control, and in particular relates to a control method for power balance of a hybrid multilevel inverter. Background technique [0002] The hybrid multilevel inverter can output more levels when the number of cascaded units is the same, has a better voltage waveform, and reduces output total harmonic distortion. Usually, a hybrid multilevel inverter consists of 1 to 2 full-bridge inverter units and a diode-clamped inverter unit in accordance with figure 1 The structure is cascaded. Compared with the traditional multi-level inverter, it uses different DC voltage ratios to output more levels. With these advantages, hybrid multilevel inverters are widely used in active power filters, high-voltage high-power motors and other fields. [0003] The hybrid multi-level inverter adopts the traditional hybrid modulation strategy, and the high-voltage unit uses a fixed comparison level to output the compos...

Claims

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Application Information

Patent Timeline

10 Sep 2014

Publication

CN104038092A

IPC: H02M7/49; H02M7/487; H02M7/5387

Inventors: 南余荣; 王源汇