Monopole inverter capable of boosting voltage

Abstract

The invention relates to a novel monopole inverting circuit capable of boosting voltage, and topology is shown in an attached figure. Besides a three-phase switch bridge (B) of the conventional voltage type inverter, the circuit is additionally provided with a tightly coupled inductor consisting of inductors (L1, L2), a capacitor (C), an interdiction diode (D) and a switch tube (T) for an energy feedback passage (can be removed if no energy is needed to feedback). The voltage boosting control mode of the circuit to an inverter direct current bus uses the state of the through zero vector of the upper and lower switch tubes emitted by the three-phase inverter bridge during zero vector to adjust the action time so as to realize the controllable promotion of direct current bus voltage of the input side of the inverter. The inductors (L1 and L2) are tightly coupled, when the inductors are in a state of through zero vector, the inverter is directly communicated, and a DC voltage source (Vs)charges a couple inductor (L1); and when the inductors are in a state of non-through zero vector, the inductors release energy to supply power to the direct current bus of the inverter (B); the voltage of the direct current bus of the inverter is obtained by lapping the voltage of the inductor (L2) and the voltage of the capacitor (C) so as to enable the voltage of the direct current bus of the inverter to be improved, so that the inverter voltage is boosted. The novel monopole inverting circuit capable of boosting voltage only uses a first stage transform circuit, smartly applies through zero vector which is not allowed by the traditional inverter so as to improve the DC busbar voltage of the inverter, realizes the adjustment to the busbar voltage, suits to the variational occasions which need to boost and invert or larger input voltage, and overcomes the shortage of the traditional voltage type inverter, cares nothing for the through caused by the electromagnetic interference and does not need to be inserted into a dead zone.

Description

technical field [0001] The invention relates to a novel single-stage boostable inverter, which is especially suitable for motor drive system occasions in which a DC bus needs to be powered by a low-voltage booster and new energy power generation inverter occasions suitable for a large input voltage variation range. Background technique [0002] The traditional voltage source inverter inputs DC voltage and outputs AC voltage, and has a wide range of applications. The input DC voltage of the voltage source inverter can be obtained from the power grid or the rotating AC motor through rectification and filtering, and can also be obtained from batteries, fuel cells or photovoltaic cells, corresponding to general industrial applications (such as frequency converters), electric vehicles, renewable energy Distributed power generation and other occasions. In the voltage source inverter, due to the input DC voltage, the power semiconductor device is always kept forward biased, so the...

AI Technical Summary

Problems solved by technology

For DC / AC power conversion applications with low DC voltage and higher AC output voltage, an additional DC / DC boost converter is required. This additional power conversion stage increases the cost of the system and reduces the conversion efficiency.

[0005] (3) The upper and lower devices of each bridge arm cannot be turned on at the same time, whether it is intentional or caused by electromagnetic interference, otherwise, a direct short circuit will occur and the device will be damaged

[0016] Under certain conditions, the inductance and capacitor of the Z-source network will resonate. When designing and controlling the Z-source inverter, strategies to avoid resonance must be considered. Once resonance occurs, it will affect the normal operation of the circuit.

Since the capacitor voltage is 0 when starting, there is a large starting inrush current when starting, and it is easy to cause resonance during the starting process, resulting in a large inrush current and inrush voltage, which may damage the inverter.

(2) The bus voltage of the inverter bridge is the capacitor voltage minus the inductor voltage drop. The bus voltage is lower than the capacitor voltage, and the voltage level of the capacitor cannot be fully utilized. If it is a high-voltage application, a high-voltage capacitor is required, and the volume is large

The voltage will drop, and the modulation algorithm of the inverter must consider the influence of voltage changes, which increases the complexity of inverter control

(3) Two capacitor elements are required to be symmetrical, and capacitor failure is catastrophic for this system circuit

(4) Z-source inverters are used in power transmission control, and it is not easy to realize energy feedback smoothly and realize four-quadrant operation

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