Converse-solution PWM (Pulse-Width Modulation) inverter and control method

Abstract

The invention relates to a converse-solution PWM (Pulse-Width Modulation) inverter and a control method, and belongs to the fields of power electronics, electric drive and electrical power systems. The inverter comprises a main circuit unit, a drive and power amplifier unit, a PWM module, an AD sampling module, a DSP (Digital Signal Processor), a serial port communication module, a display unit, a direct current voltage detection circuit and a direct current voltage conditioning circuit; and the inverter further comprises a voltage current detection and conditioning circuit and a power grid phase A voltage zero crossing detection and conditioning circuit. According to the inverter, the problems that a load is unbalanced and the middle of DC side voltage cannot be found are not considered, and only needed line voltage needs to be obtained; even under the condition of unbalanced load, adjustment can be carried out by using a control policy, and at the moment, the line voltage is adjusted, so no mutual interference exists; and the line voltage can be adjusted to a balanced state, and the requirement that in a practical system the line voltage output by the inverter is sine wave can be met.

Description

technical field [0001] The invention belongs to the field of power electronics, power transmission and power systems, and in particular relates to a reverse-solution PWM inverter and a control method. Background technique [0002] The development of new energy makes the application of inverter more and more extensive. Among them, in the new energy power generation system with three-phase inverter as the power interface unit, there are many inverter control methods. The traditional inverter The control methods mainly include SPWM and SVPWM. These methods are modulated according to the three-phase phase voltage as the modulation wave. At this time, the three-phase phase voltage output by the system can only be balanced when the load and the middle point of the DC side voltage are clear. In the actual application system, because it is difficult to find and connect the midpoint of the three-phase phase voltage output by the inverter system and the midpoint of the DC side voltage...

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Problems solved by technology

[0002] The development of new energy makes the application of inverter more and more extensive. Among them, in the new energy power generation system with three-phase inverter as the power interface unit, there are many inverter control methods. The traditional inverter The control methods mainly include SPWM and SVPWM. These methods are modulated according to the three-phase phase voltage as the modulation wave. At this time, the three-phase phase voltage output by the system can only be balanced when the load and the middle point of the DC side voltage are clear. In the actual application system, because it is difficult to find and connect the midpoint of the three-phase phase voltage output by the inverter system and the midpoint of the DC side voltage of the inverter, it is difficult to find the real phase voltage output by the system. Once the load is unbalanced or the DC There is an error in finding the midpoint of the side voltage. Even if an advanced control strategy is used to adjust the system, because of the coupling between the three-phase voltages, the obtained three-phase voltage is still unbalanced, so the line voltage is also unbalanced. Balanced, that is, it cannot guarantee that the line voltage output by the three-phase inverter is the expected sinusoidal waveform. In practice, although the load is connected to the phase voltage on the surface, it is actually a line voltage in essence, no matter what the characteristics of the load are. Yes, as long as the line voltage is a sinusoidal waveform, it can meet the requirements

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