Inverter circuit board repair tips

General-purpose inverter main circuit At present, domestic-made inverters are mainly low-voltage general-purpose inverters on the market. The following description is convenient. The main circuit structure of general-purpose inverters is briefly introduced. The AC-AC inverters are divided from the inverter structure. And AC-DC-AC frequency converters, from the frequency conversion characteristics of the main voltage source inverter and current source inverter, the current domestic production of the inverter mainly to voltage source AC-DC-AC inverter main circuit Mainly by the rectifier circuit, filter circuit, inverter circuit and braking unit and other components, including IGBT (Insulated Gate Bipolar Transistor) constitute the main hardware of the inverter, the circuit functions of each part are briefly described as follows:

(1) The rectifier circuit consists of VD1~VD6 three-phase bridge full-wave rectifier circuit to rectify the three-phase AC power into DC power.

(2) The DC voltage output by the rectifier circuit of the filter circuit is the pulsating DC voltage, and therefore the filter circuit is required to filter out the voltage ripple, and it also plays an energy storage role in the rectifier circuit and the inverter circuit.

(3) Inverter circuit consists of switching tubes V1 ~ V6 constitute the inverter circuit to convert the DC voltage into a three-phase frequency, voltage adjustable AC to drive the three-phase motor, inverter frequency conversion is the key link.

(4) The current-limiting circuit consists of a current-limiting resistor R and a switch K. Since the capacitor voltage at the moment of power-on is zero, the charging current of the capacitor at the moment of power-on is large. Excessive current may damage the rectifier circuit and protect the rectifier circuit. The instantaneous current limiting resistor of the inverter is connected in series to the DC loop. When the capacitor is charged for a certain period of time, the resistor is short-circuited by the switch K.

(5) The braking circuit is composed of braking resistor RB and switching tube VB. The main function is to consume the energy fed back by the motor to avoid excessive pumping voltage damage to the inverter. Convoy Universal G/P series inverters have different brands of Opec, Mitsubishi, Toshiba, etc. depending on the power level. The main circuits of inverters with power below 18.5 kW mainly use set rectification and inverse. The seven-unit module consists of variable, brake circuit and temperature detection. The 22kW and above models use a rectifier module and three 2-way inverter modules.