Frequency conversion drive system of pulse width modulation in AC motor

An AC motor, pulse width modulation technology, applied in the direction of AC motor control, control system, electrical components, etc., can solve the problems of affecting cost and high price, and achieve the effect of saving cost, improving reliability and simplifying wiring.

CN1874141AActive Publication Date: 2006-12-06JINLING ELECTRICAL CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2006-12-06

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Abstract

The drive system includes DC power supply, polyphase bridge type inverter circuit controlled by controller, and driven polyphase AC motor. The DC power supply includes a positive pole, a negative pole, and a common end. The inverter circuit is in two phase's bridge type, and its buses of positive and negative sources are connected to positive and negative pole of DC power supply respectively. The motor is symmetrical motor in two phases, and common end of windings in two phases is connected to the common end. The other end of each phase winding is connected to middle point of each phase bridge arm. The controller outputs symmetrical modulation signal in two phases. The modulation is pulse width modulation of sine wave in unipolarity. Comparing with traditional system, the disclosed design possesses identical or better waveform of operating voltage and driving performance. The invention reduces feed through probability of bridge arm, and raises reliability of inverter circuit.
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Description

technical field

[0001] The invention relates to an alternating current motor pulse width modulation variable frequency driving system. In the international patent classification table, the functional classification can belong to H02P7 / 00. Background technique

[0002] At present, the typical AC motor variable frequency drive system is to control the three-phase bridge-type 6-unit inverter circuit powered by DC power in the form of pulse width modulation (PWM), convert it into a frequency-variable symmetrical three-phase power supply, and drive the three-phase AC motor. In such systems, bipolar sine wave pulse width modulation is traditionally used. The characteristics of various modulation methods can be found in "Illustration of Motor Frequency Conversion Speed ​​Regulation System" (China Electric Power Publishing House, first edition in September 2003) and "AC Speed ​​Regulation Control System" (Electronic Industry Press, first edition in March 2003) version) etc. [000...

Examples

Embodiment Construction

[0025] The AC motor pulse width modulation variable frequency drive system in the embodiment of the present invention is transformed on the basis of the prior art AC motor pulse width modulation variable frequency drive system.

[0026] The electrical block diagram of the prior art system is as follows figure 1 shown. On the three-phase frequency conversion control board, the AC (AC) input terminals 2 and 3 of the bridge rectifier BRD201 are respectively connected to the neutral line N and phase line L of the 220V (AC50HZ) single-phase AC power supply, and the direct current (DC) output terminals 1 and 4. Connect the filter circuit composed of the capacitor 225, and output the voltage of the DC bus VDD to the ground bus of about 300V. The inverter circuit consists of an A-phase bridge composed of insulated gate bipolar transistors IGBT201 and IGBT202, a B-phase bridge composed of IGBT203 and IGBT204, and a C-phase bridge composed of IGBT205 and IGBT206, which are connected be...