Uninterruptible power supply

Abstract

The invention discloses an uninterrupted power supply, which comprises an AC energy input, a DC power supply, a controllable switch, a boosting module and an inverter module, wherein the DC power supply consists of a battery pack; the boosting module includes an inductor, a first and a second switch tubes, a first and a second capacitors, a rectifying tube, a third and a fourth diodes, and a twelfth diode for preventing current from flowing through the first switch tube in negative phase AC state; the input terminal of the inductor is coupled with a live wire and the positive electrode of the DC power supply, and the output terminal is connected with the first terminal of the rectifying tube and coupled with the first terminal of the first switch tube; the third diode is connected with the first terminal of the first switch tube at the first terminal and connected with the negative electrode of the DC power supply through the first capacitor, the second capacitor and the fourth diode at the second terminal; a zero wire is coupled with the second terminal of the first switch tube and the first terminal of the second switch tube and connected between the first and the second capacitors; and the second switch tube as well as the second terminal of the rectifying tube is connected with the negative electrode of the DC power supply. The invention only needs one group of batteries and inductors which is at low cost.

Description

technical field [0001] The invention relates to an uninterruptible power supply. Background technique [0002] Such as figure 1 As shown, the existing uninterruptible power supply (UPS) generally includes AC power input, DC power supply, controllable switch, booster module and inverter module, and the controllable switch is configured to selectively input AC power or The DC power supply is connected to the boost module, and the boost module is used to boost the input voltage and output it to the inverter module, and the inverter module is used to convert the voltage output by the boost module into an AC voltage for output. The existing DC power supply includes two sets of batteries V1 and V2, which are respectively responsible for the positive phase and negative phase power supply in the battery mode. The boost module includes two sets of inductors L1, L2, two switch tubes Q1, Q2, two diodes D5, D6, and capacitors C1, C2. Most of the existing inverter modules adopt the ha...

AI Technical Summary

Problems solved by technology

[0003] The disadvantage of this uninterruptible power supply is that two sets of batteries and two sets of inductors need to be set, which will lead to a substantial increase in the overall cost of the UPS

Because the inductor L1 works in the positive phase and does not work in the negative phase; the inductor L2 works in the negative phase and does not work in the positive phase, and the utilization rate of the inductor is low

When the output power of the UPS is high, several tubes Q1 and Q2 need to be used in parallel, because the switching time and characteristics of the power tubes cannot be completely consistent, and the power tubes cannot achieve good current sharing, which may reduce the overall system performance. reliability

In a 220V AC output system, the bus voltage needs to be increased to about ±400V, and the inverter module of the half-bridge inverter topology is used. The power switch tubes Q3 and Q4 need to use tubes with a withstand voltage of 1200V, and the tubes with a withstand voltage of 1200V are expensive; The switching frequency behind the 1200V withstand voltage tube should not be too high, the filter volume is large, and the cost is high; in addition, the inverter module adopts the half-bridge inverter topology, and the inverter module works in a two-level state, the voltage ripple is large, the filter volume is large, and the cost is high. High; the inverter module will charge the bus capacitor during the freewheeling period of the inductor L3, causing the voltage fluctuation on the bus capacitor to become larger or even out of control. Additional bus voltage balancing measures are required

For example: during normal phase operation: when Q3 is turned on, capacitor C1 charges inductor L3; when Q3 is turned off, inductor L3 discharges through C3, C2, and D4, and the discharge current will charge C2, while during normal phase operation, the bus capacitance C2 is uncontrolled, making the voltage on C2 fluctuate more

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