A mixed modulating method for three level high-voltage transducer

A high-voltage frequency converter and hybrid modulation technology, applied in the direction of converting irreversible DC power input into AC power output, electrical components, output power conversion devices, etc., can solve the problem of three-level PWM technology with a single PWM method, storage Higher volume requirements, not flexible enough control, etc., to improve waveform quality, not increase storage capacity, and improve system efficiency

Inactive Publication Date: 2007-08-15
TSINGHUA UNIV +1
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Problems solved by technology

The disadvantage is that the switching angle is fixed, offline calculation is required, it is difficult to implement online, and the control is not flexible enough. Especially at low frequencies, due to the large switching angle, the storage capacity is relatively high.
[0004] At present, most of the research on three-level PWM technology uses a single PWM method. How to use two PWM methods at the same time and ensure smooth switching between the two has not yet been published in published papers and related patents.

Method used

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  • A mixed modulating method for three level high-voltage transducer
  • A mixed modulating method for three level high-voltage transducer
  • A mixed modulating method for three level high-voltage transducer

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Embodiment Construction

[0046] The present invention is applied to a three-level high-voltage frequency converter, and a DSP (digital signal processor) of TI Company of the United States is used to generate PWM pulses. The model is TMS320LF2407A. The application block diagram of the actual system is shown in Figure 8. Six channels of pulses are generated in the DSP, and the trigger pulses of 12 channels of switching devices are obtained after the CPLD completes the dead zone processing. The specific algorithm adopts mixed programming of C language and assembly language. The present invention comprises two kinds of PWM algorithms of SVPWM and SHEPWM, all realizes in the underflow interrupt in DSP, and concrete implementation steps are introduced as follows:

[0047] 1. Set the target frequency f aim , and then pass the target frequency through the ramp function to get the current frequency f now , the ramp function is used to convert a given target frequency into a slowly changing current frequency,...

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Abstract

The disclosed modulation technology for three-level high-voltage frequency converter comprises: to three-level NPC frequency converter, using asynchronous SVPWM when frequency less than 45Hz, and obtaining switch frequency as 600Hz; using special eliminating-harmonic PWM when frequency over 45Hz, and obtaining the switch number is seven. This invention avoids defects of space-vector PWM and special eliminating-harmonic PWM, improves waveform quality, reduces heat loss and request on filter, and ensures system security and reliability.

Description

technical field [0001] The invention belongs to the technical field of power electronics application, and is aimed at the generation of PWM pulses of three-level high-voltage frequency converters. Space vector PWM is adopted at low frequencies, the DC bus voltage utilization rate is high, and it is easy to digitize. Specific harmonic elimination PWM is adopted at high frequencies to eliminate The low-order harmonics are reduced, the waveform quality is improved, and the heat loss can be greatly reduced. The method of switching at a fixed angle ensures smooth switching between the two PWMs. Background technique [0002] Compared with the two-level diode neutral point clamped (Neutral Point Clamped) three-level inverter, it can use low withstand voltage devices to achieve high voltage and large capacity, the output waveform is closer to sinusoidal, and the device’s bearing capacity can be reduced under the same DC bus voltage. Compressive stress is one of the main application...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/48H02M7/5387
Inventor 张永昌赵争鸣杨志白华
Owner TSINGHUA UNIV
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