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A Harmonic Optimal Modulation Method for Multilevel Inverter

A technology of multi-level inverter and modulation method, which is applied in the direction of electrical components, output power conversion devices, AC power input conversion to DC power output, etc., which can solve the problem that the number of harmonics to be eliminated is limited and the number of phase shifts is impossible If the problem is too large, it can achieve obvious suppression effect

Active Publication Date: 2017-03-08
CHINA UNIV OF MINING & TECH (BEIJING)
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Problems solved by technology

[0015] The phase-shift superposition method described above is to eliminate the specified harmonics. Since the number of levels is exponentially related to the number of phase shifts, limited by the number of levels, the number of phase shifts is generally not too large, so the number of harmonics eliminated is limited.

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  • A Harmonic Optimal Modulation Method for Multilevel Inverter
  • A Harmonic Optimal Modulation Method for Multilevel Inverter
  • A Harmonic Optimal Modulation Method for Multilevel Inverter

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specific Embodiment

[0034] Specific embodiment: for the H-bridge cascaded three-phase five-level inverter, its single-phase circuit topology is as follows figure 2 As shown, it is formed by cascading two full bridge circuits. DC1 and DC2 are two independent DC power supplies with the same voltage, S11, S12, S21, and S22 are P-channel MOSFETs, and S13, S14, S23, and S24 are N-channel MOSFETs, which ensures that two of the same bridge arm The switch tube is always in the interlock state under the same driving signal, and the output voltage is V_Phase.

[0035] Step S1: The number of switching angles is N=4, the modulation ratio m=0.8, and the harmonic elimination equations can be obtained from (Formula 3) as follows:

[0036] (Formula 6)

[0037] By solving (Formula 6) to eliminate the 5th, 7th, and 11th low-order harmonics, there are two sets of solutions to solve the two-level SHE equations:

[0038] (16.0218°, 20.3013°, 73.5548°, 78.0900°),

[0039] (12.4540°, 21.3973°, 42.0624°, 46.5430...

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Abstract

The invention discloses a harmonic optimization and modulation method suitable for a multi-level converter. The technical means of selective harmonic elimination pulse width modulation and the technical means of phase shifting are combined in the method. For low-order harmonics, the low-order harmonics are eliminated by solving a two-level selective harmonic elimination equation set; for high-order harmonics, optimization is carried out on the total number of several orders of harmonics with the phase shifting angle as a variable, phase shifting superposition is carried out on two-level waveforms through the phase shifting angle obtained through optimization to obtain multi-level waveforms, and finally a control signal of each switching tube is determined according to the multi-level waveforms. By means of the method, several orders of low-order harmonics can be eliminated, the suppression effect on the high-order harmonics is obvious, and the calculation amount is hardly increased.

Description

technical field [0001] The present invention relates to the field of power electronic systems and control methods thereof, in particular to control, harmonic elimination and optimization methods for inverters and multilevel converters, and in particular to a modulation method for multilevel inverters method. Background technique [0002] Due to the advantages of large output capacity, low harmonic content of output voltage and current, low reverse voltage of the switching tube, and small switching loss, multi-level inverters are widely used in the fields of medium and high voltage speed regulation, AC flexible power supply systems, and new energy power generation. has been widely applied. Multilevel inverters have a variety of topologies, such as cascaded, diode clamped, flying capacitor and hybrid, etc., and the recently developed Modular Multilevel Converter (Modular Multilevel Converter) is also a It is considered to be a multi-level inverter with great development pros...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/483H02M1/12
CPCH02M1/12H02M7/483
Inventor 杨克虎袁志宝
Owner CHINA UNIV OF MINING & TECH (BEIJING)
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