Good or bad way to test inverter rectifier bridge with multimeter
With a multimeter resistance block can judge the inverter rectifier bridge damage, the parallel rectifier bridge to loosen the connectors, find the bad one.
1, test the rectifier circuit
The multimeter will be adjusted to the resistance X10 file, the red pen to the P terminal, the black pen to the R, S, T terminal, there should be about tens of ohms of resistance, and the basic balance. Connect the black pen to the P terminal, the red pen to the R, S, T in turn, there is a resistance value close to infinity. The red pen to the N terminal, repeat the above steps, should have the same results. If the resistance value of the three-phase imbalance or the red pen to the P terminal, the resistance is infinite, you can determine that the circuit has been abnormal, rectifier bridge failure.
2, test the inverter circuit
The red pen to the P terminal, the black pen to the U, V, W in turn, there should be a few tens of ohms of resistance, and the resistance value of each phase is basically the same, the black pen to the P terminal, the red pen to the U, V, W in turn, there is a close to infinity of the resistance value. The black pen to the N terminal, repeat the above steps, you should get the same results, otherwise you can determine the inverter module failure.
In the rectifier circuit and inverter circuit test is normal, only after the power-up test. Before and after power-on according to the contents of the fault display, determine the fault and cause.
Damage cause analysis:
(1) The device itself is of poor quality;
(2) The rear stage circuit and inverter power switching device are damaged, resulting in the rectifier bridge flowing through the short-circuit current and damage;
(3) The grid voltage is too high, and the grid is exposed to lightning strikes and overvoltage surges. The internal resistance of the grid is small, and the varistor for overvoltage protection has burned out and does not work, resulting in all the overvoltage added to the rectifier bridge;
(4) The power transformer of the inverter and the power grid is too close, the line impedance in the middle is very small, and the inverter is not installed with DC reactor and input side AC reactor, which puts the rectifier bridge in the state of capacitive filtering of the high amplitude of the sharp pulse current impact, resulting in premature damage to the rectifier bridge;
( (5) Input phase loss, so that the rectifier bridge burden and damage.
Find the root cause of rectifier bridge damage, and eliminate, to prevent the replacement of the new rectifier bridge and damage.
(1) Replace the new rectifier bridge, the welding of the rectifier bridge need to ensure that the welding is reliable. Ensure that the electrical safety with the peripheral components of the spacing, screw connection should be tightened to prevent contact resistance and heat. With the heat sink has a conductive thermal conductivity, require a good coating of silicone grease to reduce the thermal resistance;
(2) The parallel rectifier bridge to use the same model, the same manufacturer's products to avoid uneven current and damage.
1. Half-bridge detection half-bridge is composed of two rectifier diodes, by using a multimeter to measure the two diodes inside the half-bridge, respectively, positive and negative resistance value is normal, you can judge whether the half-bridge is normal.
2. full-bridge detection of most of the rectifier full-bridge, are marked with "+", "-", "~" symbols (of which "+" is the output value of the rectified output). " for the positive output voltage after rectification, "-" for the negative output voltage, "~" for the AC voltage input), it is easy to determine the electrodes.
Detection, by measuring the "+" pole and the two "~" pole, "-" pole and two "~" Between the rectifier diode positive and negative resistance value (and ordinary diode measurement method is the same) is normal, you can judge whether the full bridge has been damaged. If measured within the full bridge whip diode forward and reverse resistance values are 0 or infinity, it can be judged that the diode has been damaged by breakdown or open-circuit.
