PWM (Pulse Width Modulation) pulse width dynamic adjustment and neutral-point balance method based on current observer

A current observer and dynamic adjustment technology, applied in electrical components, circuit devices, AC network circuits, etc., can solve problems such as current coupling, disordered harmonics, and insufficient adjustment capability.

Active Publication Date: 2021-09-14
TIANJIN RES INST OF ELECTRIC SCI
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Problems solved by technology

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art, propose the PWM pulse width dynamic adjustment and midpoint balance method based on the current observer, solve the PWM response hysteresis in the existing conventional look-up table control, current coupling, disorder and harmonic in the...

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  • PWM (Pulse Width Modulation) pulse width dynamic adjustment and neutral-point balance method based on current observer
  • PWM (Pulse Width Modulation) pulse width dynamic adjustment and neutral-point balance method based on current observer
  • PWM (Pulse Width Modulation) pulse width dynamic adjustment and neutral-point balance method based on current observer

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Embodiment Construction

[0057] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0058] Such as Figure 5 As shown, the usual PWM modulation strategy uses the carrier wave to compare with the triangular wave to produce PWM modulated pulses. This modulation method has the advantage of simplicity and ease when the harmonics are not large at high carrier ratios, but the ratio harmonics are large at low carrier ratios.

[0059] Such as Figure 6 As shown, the optimized PWM modulation strategy obtains a set of switching angles through offline numerical calculation to achieve the minimum output harmonics. However, the optimal PWM strategy cannot be directly used in high-performance systems such as vector control, because it will cause PWM disorder and system overcurrent in dynamics.

[0060] PWM pulse width dynamic adjustment and midpoint balance method based on current observer, such as figure 1 shown, including the following steps:

[00...

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Abstract

The invention relates to a PWM pulse width dynamic adjustment and neutral point balance method based on a current observer, and the method is technically characterized in that a current fundamental component is extracted through current observation, the dynamic adjustment time and the steady-state adjustment voltage are calculated, the adjustment output level time is calculated through neutral point balance, and the adjustment output level time and the dynamic adjustment time are input to the pulse width adjustment to complete the adjustment of the PWM pulse width. The problems that PWM response lags behind in existing conventional table look-up control, current coupling and disorder exist in the adjusting process, harmonic waves are increased and the like are solved, the advantage that the current harmonic waves of an optimized PWM table look-up method are low is reserved, meanwhile, the defect of an existing neutral-point balance technology is overcome, the limitation that common-mode component adjustment must be used is broken through, and the problems of insufficient adjustment capability and poor real-time performance caused by limitation of zero-sequence voltage adjustment in an existing method are solved.

Description

technical field [0001] The invention belongs to the field of PWM pulse width modulation, in particular to the dynamic adjustment of PWM pulse width based on a current observer and its midpoint balance method. Background technique [0002] At present, the domestically developed three-level inverters have begun to be put into industrial applications, but compared with similar foreign inverters, there is a problem that the maximum output power is low. Reducing the PWM switching frequency is one of the effective ways to increase the output power of the inverter, but when the ratio of the switching frequency to the output fundamental frequency is low, the output current waveform pulsation and harmonics are large under asynchronous PWM, and the corresponding torque pulsation is large, while optimizing the PWM When the look-up table method is used in vector control with low switching frequency, there are problems such as response lag, current disorder, and the system is difficult t...

Claims

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Application Information

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IPC IPC(8): H02M7/483H02M1/08H02J3/38
CPCH02M7/483H02M1/08H02J3/381
Inventor 田凯俞智斌楚子林姜一达王自满孙传杰李楠杨敬然宋鹏
Owner TIANJIN RES INST OF ELECTRIC SCI
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