A Discontinuous Pulse Width Modulation Method for Midpoint Potential Balance of Three-level Converter
A technology of pulse width modulation and potential balance, applied in high-efficiency power electronic conversion, conversion of AC power input to DC power output, electrical components, etc., can solve problems such as increased cost, modulation is limited by stages, and complex control Small switching loss, good harmonics and control effects, and low system cost
Active Publication Date: 2018-10-02
中科海奥(黄山)储能科技有限公司
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Problems solved by technology
[0012] Using soft switching technology can effectively reduce the switching loss of power tubes, but the application of soft switching will increase the cost, the control is complicated, and the modulation is limited by stages
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[0056] In this embodiment, a discontinuous pulse width modulation method for midpoint potential balance of a three-level converter is to detect the upper and lower capacitor voltages, phase voltages, and phase currents on the DC side in real time, and determine the magnitude relationship of the three-phase output voltages. Select the appropriate clamping mode and carrier mode according to the voltage difference between the upper and lower capacitors, inject the corresponding common-mode voltage, and then obtain the corresponding switching sequence, specifically, as figure 2 As shown, proceed as follows:
[0057] Step 1. Use the voltage sensor and current sensor to collect the upper and lower capacitor voltage u on the DC side of the three-level converter C1 , u C2 , three-phase output voltage u A , u B , u C , three-phase current i A i B i C ;
[0058] Define Δu in the specific implementation c = u C1 -u C2 is the voltage difference between the upper and lower capa...
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The invention discloses a discontinuous pulse width modulation method for neutral point potential balance of a three-level converter, comprising: 1. collecting the upper and lower capacitor voltages, three-phase output voltages and three-phase currents of the DC side of the three-level converter; 2. Compare the magnitude relationship of the three-phase output voltage of the three-level converter; 3. Calculate the midpoint current under different clamping methods; 4. Select the appropriate midpoint current according to the instantaneous midpoint potential, modulation degree and calculated midpoint current 5. According to the selected clamping method, select the corresponding carrier mode to obtain the three-phase switching sequence. The invention can effectively control the midpoint potential of the three-level converter, reduce the switching loss of the power device, thereby realizing the optimal control of the three-level converter.
Description
technical field [0001] The invention relates to a control method of a three-level converter, and more specifically relates to a discontinuous pulse width modulation method for midpoint potential balance of the three-level converter. Background technique [0002] With the development of power electronics technology, especially in large-capacity and high-voltage applications, the application of three-level topology is more and more extensive, and the voltage that each power tube bears is half of the DC side voltage. In addition, the three-level topology also has the advantages of low harmonic content of the output waveform and high efficiency. However, due to the increase in the number of power tubes, the control algorithm is complex, accompanied by problems such as midpoint potential offset. [0003] In order to make the three-level inverter operate safely and reliably, it must be ensured that the midpoint potential is half of the DC side voltage. There are three common met...
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IPC IPC(8): H02M7/487H02M7/5395
CPCH02M7/487H02M7/5395H02M1/0054Y02B70/10
Inventor 姜卫东王磊张学威王金平皋艳
Owner 中科海奥(黄山)储能科技有限公司