Hybrid modulation-based control method for mid-point voltage balance of multilevel inverter

A multi-level inverter and voltage balancing technology, which is applied to electrical components, output power conversion devices, and conversion of AC power input to DC power output. Large and other problems, to achieve the effect of high output waveform quality, reduced inductor current ripple, and improved conversion efficiency

Inactive Publication Date: 2014-04-23
NANJING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] 1) The deviation of the actual capacitance value due to the error of the manufacturing process;
[0005] 2) The characteristics of the switching tube are inconsi

Method used

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  • Hybrid modulation-based control method for mid-point voltage balance of multilevel inverter
  • Hybrid modulation-based control method for mid-point voltage balance of multilevel inverter
  • Hybrid modulation-based control method for mid-point voltage balance of multilevel inverter

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Embodiment 1

[0090] In order to verify the feasibility of a multi-level inverter mid-point voltage balance control method based on hybrid modulation proposed by the present invention, a three-level inverter circuit was built using the Simulink tool in MATLAB. The level circuit inverts and outputs the three-phase voltage, and the EMI filter circuit outputs a smooth sinusoidal voltage waveform. The electrical parameter settings in the simulation process are as follows:

[0091]

[0092] Figure 7 is the DC bus capacitor C under the above electrical parameter settings 1 、C 2 The voltage V c1 , V c2 simulated waveform. The control mode of the present invention is added at the time of 0.02s. When the control mode of the present invention is not added, the DC bus capacitor C 1 、C 2 The voltage V c1 , V c2 The average value difference of 30V is about 30V, and the midpoint voltage is seriously unbalanced. After adding the control method of the present invention at 0.02s, it can be seen...

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Abstract

The invention discloses a hybrid modulation-based control method for the mid-point voltage balance of a multilevel inverter. The method comprises the following steps: detecting a capacitance transient voltage between the midpoint and the anode and a capacitance transient voltage between the midpoint and the cathode of a direct-current bus of the multilevel inverter by a sampling unit of a digital processing control module within each control period, and determining the bias of the two capacitance transient voltages; selecting an SVPWM (space vector pulse width modulation) or DPWM (digital pulse width modulation) control mode through a pulse width modulation strategy switching unit to work; outputting a control signal through an SVPWM/DPWM control processing unit; outputting a PWM signal through a drive circuit to control the working condition of each phase bridge arm switch tube of the multilevel inverter, and meanwhile, controlling the mid-point voltage balance of the multilevel inverter. The control method disclosed by the invention has the advantages that the switching frequency is reduced, the switching loss is reduced, output voltage and current harmonics are small, the output waveform quality is high, digital realization is convenient, and the like, and has an important engineering application value.

Description

technical field [0001] The invention belongs to the technical field of control in power electronic conversion technology, in particular to a hybrid modulation-based midpoint voltage balance control method of a multilevel inverter. Background technique [0002] The traditional two-level inverter has a simple control method and is easy to implement, but it also has the disadvantages of high output harmonic distortion rate, large voltage stress on the switching tube, and low efficiency. Multilevel inverters have the advantages of low withstand voltage level of switching devices, high equivalent switching frequency and small output waveform harmonics, so they are widely used in medium and high voltage high power conversion circuits. In order to generate multiple levels in the output phase voltage, two DC bus capacitors must be used in both T-type and NPC-type inverter topologies. Ideally, the voltage of each capacitor is half of the DC bus voltage, but in reality, both topologi...

Claims

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Application Information

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IPC IPC(8): H02M7/483H02M7/487H02M7/5387
Inventor 吕建国胡文斌吴馥云吴军基
Owner NANJING UNIV OF SCI & TECH
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