Active bi-directional electric power adjuster

Abstract

This invention relates to an active two-way power regulator including a DC end, a two-way DC / DC power converter, a DC / AC inverter and an AC end, in which, said DC end can be connected to a DC supply, said two-way DC / DC converter utilizes a HF pulse width modulation technology to generate a pre-set DC voltage or a DC current, said DC / AC inverter is taken as a LF reversing gear to convert the DC voltage or current to a preset AC voltage or current and the AC end can be connected to a load and an AC supply selectively.

Description

technical field [0001] The invention relates to a bidirectional power conditioner, in particular to an active bidirectional power conditioner composed of a bidirectional DC / DC power converter and a DC / AC inverter. Background technique [0002] Active power conditioners are often used to improve the power quality of the load and improve the power characteristics of the load. For example, the DC terminal of the active power conditioner is connected to a battery to form an off-line uninterruptible power supply system. When the power supply is normal, the utility power supplies power to a load through the bypass path inside the offline uninterruptible power supply system, and charges the battery inside the offline uninterruptible power supply system; when the utility power supply is abnormal, the The off-line uninterruptible power supply system converts the DC power of the internal storage battery into an AC power to supply the load, thereby preventing the load from being affect...

AI Technical Summary

Problems solved by technology

However, due to cost and technical reasons, the output voltage waveform of traditional off-line uninterruptible power system discharge is mostly square wave, and the square wave output voltage will cause harm to some loads (such as transformers). If the square wave output voltage When the off-line uninterruptible power system is connected to the power supply load with power factor correction, it will also cause the over-current protection of the off-line uninterruptible power system with square wave output voltage, which will cause damage

[0003] In view of the above problems, many off-line uninterruptible power supply system devices with sine wave voltage output have been developed. The off-line uninterruptible power supply system with sine wave voltage output in the prior art, such as U.S. Patent No. 5,625,539, which discloses when When the mains power supply is normal, the mains supply the energy required by the load; when the mains power supply is abnormal, a unidirectional DC / DC power converter is used to boost the low-voltage DC energy stored in the battery into a higher voltage DC power, and store the power in a DC capacitor with a large capacitance value, and then rely on a high-frequency switching full-bridge DC / AC inverter to convert the power stored in the capacitor into a sinusoidal AC voltage and output it to the load; another set There is a group of chargers, which are responsible for charging the battery when the mains power supply is normal. The circuit structure and control circuit are complex, and the secondary converters are all switched at high frequency, resulting in low efficiency; in addition, a DC capacitor with a large capacitance value is required As an energy buffer between secondary power converters, it is not suitable for low-cost sine wave output offline UPS systems

[0004] Another existing off-line uninterruptible power supply system with sine wave output, such as U.S. Patent No. 6,094,363, which discloses that when the mains power supply is normal, the energy required by the load is supplied by the mains power supply; when the mains power supply is abnormal , use a unidirectional DC / DC power converter to boost the DC voltage of the battery into a voltage waveform similar to full-wave rectification, and then rely on low-frequency switching DC / AC inverters to convert the full-wave rectified voltage waveform into a sinusoidal AC The voltage is output to the load; there is also a set of chargers with energy recovery function, which is responsible for charging the battery or recovering excess energy to the battery. This circuit structure does not require a DC capacitor with a large capacitance value as a secondary power converter. There is only one power conversion stage for high-frequency switching, so it has the advantages of simple control circuit and high efficiency, but it needs an additional set of chargers to charge the battery and recover the excess load capacity, which will lead to an increase in cost

[0005] In addition, the DC terminal of the active power conditioner can also be connected to a solar battery or other renewable energy sources, as an energy conversion interface between the solar battery or other renewable energy sources and a power distribution system, and the traditional solar cells and the power distribution system The energy conversion interface consists of two power conversion stages (a DC / DC converter and a DC / AC inverter), such as US Patent No. 6,914,418, which utilizes the DC / DC converter to convert the low-voltage DC power generated by the solar cell Convert it into high-voltage DC power and store it in a DC capacitor with a large capacitance value, and then rely on a high-frequency switching full-bridge DC / AC inverter to convert the power stored in the DC capacitor into a sinusoidal AC voltage output to the The load or sinusoidal alternating current is sent back to the power distribution system, but the two power conversion stages of the energy conversion interface of the solar cell are controlled by high-frequency pulse width modulation technology, and this circuit structure requires a capacitor with a large capacitance value as the secondary power The energy buffer between the converters, the control circuit is complicated, and the secondary converters are all switched at high frequency, resulting in low efficiency

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