The control method of three-level inverter svpwm

Abstract

The invention relates to an SVPWM control method for a three-level inverter. The control method comprises the following steps: judging a triangular large sector and a small interval, where a given voltage space vector is, according to the amplitude and phase angle of the given voltage space vector; selecting a used voltage space vector according to the triangular large sector and the small interval; selecting a method for calculating the action time of the voltage space vector according to the triangular large sector and the small interval; implementing a nine-segment modulation mode for the voltage space vector according to that the action time of a small vector is equal to that of a redundant vector corresponding to the small vector and that each control period begins with a zero vector and ends with a zero vector; outputting a three-phase PWM pulse signal required by a switching device by virtue of a controller according to the used voltage space vector; amplifying the three-phase PWM pulse signal which is output by the controller and required by the switching device by virtue of a driving circuit, and transmitting the amplified three-phase PWM pulse signal to the corresponding switching device to realize control over the three-level inverter.

Description

technical field [0001] The invention relates to the field of inverter control for driving motors, in particular to a control method and a control device for a three-level inverter SVPWM (space vector pulse width modulation). Background technique [0002] In the application of high-power inverters, multi-level inverters have been more and more widely used due to their advantages such as low voltage withstand of switching devices, low harmonic content of output voltage, and low switching frequency. Among them, the NPC (Neutral Point Clamped) three-level inverter is the most widely used multi-level structure. It only needs an independent DC voltage source and has low requirements on hardware. The main circuit and control circuit of the NPC three-level inverter are shown in Figure 1. [0003] The PWM control strategy is one of the key technologies in the research of three-level NPC inverters. Many PWM methods have been proposed by experts and scholars at home and abroad, which ...

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Problems solved by technology

[0006] Since the traditional space voltage vector modulation mode is based on the seven-segment modulation mode, the redundant small vectors cannot be fully applied, so the role of the redundant small vectors on the midpoint potential balance cannot be fully utilized

Moreover, if the redundant small vector is fully applied in the traditional space voltage vector modulation, the state of the three-phase bridge arm switching device when transitioning from one interval to another under the condition of avoiding the direct switching of the P-N state cannot be guaranteed. switch only once

[0007] Therefore, while using space voltage vector modulation to control the three-level inverter, software algorithms or hardware devices must be added to control the balance of the midpoint potential, which complicates the control of the three-level inverter

[0008] It can be seen that the above-mentioned existing three-level inverter control method obviously still has inconvenience and defects in use, and needs to be further improved urgently.

In order to solve the above-mentioned problems, the relevant manufacturers have tried their best to find a solution, but for a long time no suitable design has been developed, and the general product has no suitable structure to solve the above-mentioned problems. This is obviously the relevant industry. Urgent problem

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