An inverter (Inverter-) popular speaking, the inverter is a direct current (DC) into an alternating current means (AC) of. It consists of an inverter bridge, control logic and filter circuit.
A 400W high power regulated inverter circuit composed of TL494. Its excitation conversion part adopts TL494, VT1, VT2, VD3, VD4 form a sink current drive circuit, and drive two two 60V/30A MOS FET switch tubes. If you need to increase the output power, you can use 3 to 4 switch tubes in parallel for each channel, and the circuit will not change. The application method of TL494 in this inverter is as follows:
The first and second feet constitute a voltage-stabilized sampling and error amplification system. The positive-phase input terminal 1 inputs the 15V DC voltage of the rectified output of the secondary sampling winding of the inverter, and the voltage is divided by R1 and R2, so that the first leg is in the inverter. There are nearly 4.7~5.6V sampling voltages during normal operation. Inverting input terminal 2 input 5V reference voltage (output by 14 feet). When the output voltage decreases, the voltage at pin 1 decreases, the error amplifier outputs a low level, and the output voltage rises through the PWM circuit. In normal time, the voltage of pin 1 is 5.4V, the voltage of pin 2 is 5V, and the voltage of pin 3 is 0.06V. At this time, the output AC voltage is 235V (square wave voltage). The fourth leg is connected to R6, R4, and C2 to set the dead time. The normal voltage value is 0.01V. The 5th and 6th feet are connected to the CT and RT. The oscillator triangle frequency is 100Hz. In normal time, the voltage of pin 5 is 1.75V, and the voltage of pin 6 is 3.73V. The seventh foot is the common ground. The 8th and 11th feet are the internal drive output triode collector, and the 12th pin is the TL494 pre-stage power supply end. The three ends control the start/stop of the TL494 through the switch S as the control switch of the inverter. When S1 is turned off, TL494 has no output pulse, so there is no current in switching tubes VT4~VT6. When S1 is turned on, the voltage of the three feet is the positive voltage of the battery. Pins 9 and 10 are internal drive stage triode emitters, and output two positive pulses with different timings. The normal voltage value is 1.8V. The 13th, 14th and 15th feet of the 14 feet output 5V reference voltage, so that the 13 feet have 5V high level, the control gate circuit, the trigger output two drive pulses, used for push-pull switch circuit. The 15th pin is externally connected with 5V voltage, which constitutes the inverting input reference voltage of the error amplifier, so that the non-inverting input terminal 16 constitutes a high-level protection input terminal. In this connection, when the 16th pin inputs a high level greater than 5V, the output voltage can be reduced by voltage regulation, or the drive pulse can be turned off to achieve protection. There is almost no possibility of outputting overvoltage in the inverter, so the 16th pin in the circuit is unused and is grounded by resistor R8.
The inverter adopts a power frequency transformer with a capacity of 400 VA, and the iron core adopts a silicon steel sheet of 45×60 mm 2 . The primary winding is made of an enameled wire with a diameter of 1.2 mm, and the two are wound around 2 x 20 turns. The secondary sampling winding is wound with a 0.41 mm enamelled wire and is center tapped. The secondary winding is calculated at 230V and is wound around 400 turns with a 0.8mm enameled wire. The switching tubes VT4 to VT6 can be replaced by any type of N-channel MOS FET tube of 60V/30A. VD7 can be used with 1N400X series of common diodes. The circuit works fine with almost no debugging. When the voltage at the positive terminal of C9 is 12V, R1 can be selected between 3.6 and 4.7kΩ, or adjusted with a 10kΩ potentiometer to make the output voltage the rated value. If the output power of the inverter is increased to nearly 600W, in order to avoid excessive primary current and increase resistive loss, it is better to use 24V for the battery, and a large current MOS FET with VDS of 100V can be used for the switch. It should be noted that instead of using a single switch with an IDS greater than 50A, the reason is that one is higher in price and the other is too difficult to drive. It is recommended to use 2SK564 with 100V/32A or three 2SK906 parallel applications. At the same time, the cross section of the transformer core needs to reach 50cm2, calculate the number of turns and the wire diameter according to the calculation method of the ordinary power transformer, or replace the transformer with the waste UPS-600. If you are supplying power to a refrigerator or an electric fan, do not forget to add an LC low-pass filter.
What is an Inverter?
Date：2019-03-27 01:24:11 click：2082
