Synchronous detection circuit for frequency changing air conditioner digital voltage lifting PFC circuit

An inverter air conditioner and synchronous detection technology, applied in electrical components, AC motor control, and conversion equipment for intermediate conversion to DC conversion, etc., can solve problems such as large DC bus voltage fluctuation, lower voltage average value, and surge in compressor current. , to achieve the effect of increasing bandwidth, reducing high frequency pulse and good waveform

Inactive Publication Date: 2008-11-19
SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First, when the input circuit of the inverter is only composed of a single-phase full-wave diode rectifier bridge and a smoothing capacitor, the input current waveform is pulse-like, and the total harmonic distortion rate exceeds 100%, causing great harmonic pollution to the power grid
Second, the DC bus voltage obtained through single-phase full-wave rectification fluctuates greatly, and the average value of the voltage drops significantly under heavy load, resulting in a sharp increase in the compressor current
Therefore, the above-mentioned synchronization signal oscillation problem must be solved

Method used

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  • Synchronous detection circuit for frequency changing air conditioner digital voltage lifting PFC circuit
  • Synchronous detection circuit for frequency changing air conditioner digital voltage lifting PFC circuit
  • Synchronous detection circuit for frequency changing air conditioner digital voltage lifting PFC circuit

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Embodiment

[0035] Embodiment: The present invention is applied to the multi-connected direct current frequency conversion air conditioner dedicated inverter, and the same MCU is used to implement PFC and inverter control. The inverter adopts sine wave control without speed sensor, the switching frequency is 5kHz, and the maximum output power is 4.5kW. The PFC circuit adopts deadbeat control, and the switching frequency is 20kHz. Among them, the parameter selection of the synchronous detection circuit is as follows:

[0036] Comparator: LM311H or CA311 chip

[0037] Parallel capacitance of each diode of the rectifier bridge: C 1 =C 2 =C 3 =C 4 =2200pF

[0038] Parallel resistance at the output of the rectifier bridge: R 1 =47kΩ

[0039] Other resistors: R 2 = 300kΩ, R 3 = 4.7kΩ, R 4 = 100kΩ, R 5 = 4.7kΩ, R 6 = 1.0kΩ, R 7 = 1.0kΩ

[0040] with resistor R 6 Diodes in series D 5 : 1N4148 etc.

[0041] According to the above formula (2), (3) can get V LH =15V, V HL =229V. ...

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Abstract

This invention relates to a synchronous detection circuit of a conversion air-condition digit boosting PFC circuit including a comparing circuit, the positive input end of which is connected with a reference level, the negative input end is connected with a voltage sampling circuit linked to a rectifier circuit output end, a serial circuit of a resistor and a diode is connected between the output end of the comparator and a reference end, four diodes bridged in the rectifier circuit are parallel to a capacitor separately and the output end of the circuit is parallel to another resistor, which weakens the HF pulse interference signal overlapped on the output voltage of the rectifier circuit from a reverse circuit, and the serial resistors and diodes of the feedback loop of the comparator increases the bandwidth of the slag ring response to ensure that synchronous signals have enough pulse width.

Description

technical field [0001] The invention relates to power electronics technology, in particular to a synchronous detection circuit applied in a digital boost PFC circuit of an inverter air conditioner. Background technique [0002] In recent years, with the continuous improvement of living standards and energy-saving awareness, inverter air conditioners have been rapidly popularized. Since ordinary domestic commercial and residential buildings are usually only equipped with a single-phase 220-volt power supply, the inverter air conditioner faces the following two problems in practical application. First, when the input circuit of the inverter is only composed of a single-phase full-wave diode rectifier bridge and a smoothing capacitor, the input current waveform is pulse-like, and the total harmonic distortion rate exceeds 100%, causing great harmonic pollution to the power grid . Second, the DC bus voltage obtained through single-phase full-wave rectification fluctuates great...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02P27/06H02P27/08H02M5/44
Inventor 徐政陈锐坚李友春
Owner SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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