Inverter Operating Principle

Date: 2010/5/22      Source: Zhejiang Tress Electronic Technology Co.,Ltd.     Views: 8187

Popular speaking, the inverter is a DC (DC) into alternating current (AC) devices. It consists of inverter,control logic and filter circuit.

Formed using TL494 400W power inverter voltage regulator circuit. It excited Transformation part is TL494, VT1, VT2, VD3, VD4 form filling current drive circuit, the two two-way drive of the MOS FET switch 60V/30A. For increased output power per channel can be used 3 to 4 switch parallel applications, the circuit remain unchanged. TL494 in the inverter application is as follows: 


1,2 feet constitute regulator sampling, error amplifier, 1 input pin is input phase inverter sub-sampling winding rectifier 15V DC voltage output by R1, R2 divider to 1 foot in the inverter normal working hours, nearly 4.7 ~ 5.6V voltage sampling. Inverting input 2-pin 5V reference input voltage (from 14 feet out). When the output voltage decreases, a lower pin voltage error amplifier output low, the output voltage by PWM circuit increased. Normal value when a pin voltage 5.4V, 2-pin voltage value of 5V, 3-pin voltage value of 0.06V. Then the output AC voltage 235V (square wave voltage). 4-pin external R6, R4, C2 set the dead time. Normal voltage value is 0.01V. 5,6 feet first external CT, RT triangular wave oscillator frequency setting 100Hz. Normal value of 5 pin voltage 1.75V, 6 foot voltage value 3.73V. 7 feet for a total land. No. 8,11 feet to the internal drive output transistor collector, and 12 feet before the class for the TL494 supply side, the three-terminal switch S controlled by TL494 start / stop, as the inverter control switch. When S1 is off, TL494 no output pulse, switch VT4 ~ VT6 therefore no current. S1 connected to, this three-legged voltage value of the positive battery voltage. 9,10 feet to the internal drive first level transistor emitter, the output is different from two-way timing pulse. Normal voltage value of 1.8V. No. 13,14,15 14 feet 5V reference voltage output pin, so that there is 5V 13 feet high, the control gate, flip-flop output two-way drive pulse for the push-pull switching circuit. 15-pin external 5V, constitutes error amplifier inverting input reference voltage, so that input with the phase composition of 16 feet high to protect inputs. This access method, when the first input is greater than 5V, 16 feet high, by reducing the role of regulator output voltage, or off-drive pulse and to achieve protection. In its excited inverter output almost no possibility of excess pressure, so the circuit does not use 16 feet from the ground resistor R8. 

 
The capacity of 400VA inverter with the power frequency transformer, iron core with 45 × 60mm2 of silicon steel. The primary winding of enameled wire with diameter 1.2mm, 2 and 2 × 20 turns around. Sub-sampling winding 36 turns with 0.41mm enamelled wire around the center tap. Calculated in accordance with 230V secondary winding, with around 400 turns 0.8mm enamelled wire. Switch VT4 ~ VT6 available 60V/30A any type of pipe instead of N-channel MOS FET. VD7 available 1N400X series ordinary diode. The circuit can hardly work without debugging. When C9 is extreme when the voltage is 12V, R1 can choose between 3.6 ~ 4.7kΩ, or adjust the 10kΩ potentiometer, the output voltage rating. If this inverter output power increases to nearly 600W, in order to avoid excessive primary current, increasing the resistive losses, should the battery switch to 24V, VDS optional switch for the 100V high current MOS FET control. It must be noted that, would rather use multiple parallel, but not selected IDS alone is greater than 50A of the switch, the reason is: a price is higher, two drive too difficult. Suggested the use of 100V/32A the 2SK564, 2SK906, or use three parallel applications.Meanwhile, the transformer core cross-section needs to 50cm2, calculated by ordinary power transformer calculated number of turns and diameter, or using waste UPS-600 in transformer maintenance. Such as refrigerators, electric fans power supply, do not forget to join LC low-pass filter.

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