Detecting approach and device of motor controller pre-fill line breakdown

Abstract

The invention discloses a detecting approach and a device of motor controller pre-fill line breakdown, and the approach is applied to a motor controller pre-fill circuit. The motor controller pre-fill circuit comprises a closed loop circuit composed of a direct current power supply, a first main relay, a motor controller and a second main relay which are sequentially connected, and the first main relay is in parallel connection with a pre-fill relay and a resistor which are connected in series. The approach includes real-time monitoring a first voltage of the two ends of the motor controller and the grand total time of circuit connection after the second main relay and the pre-fill relay are connected and communicated, real-time grand total first connecting time is acquired as the first voltage is equal to a second voltage of two ends of the direct current power supply, the second relay and the pre-fill relay are controlled and disconnected, and a disconnecting signal is emitted as the first connecting time is less than the shortest pre-filled charging time. The invention further discloses a motor controller pre-fill line breakdown detecting device.

Description

technical field [0001] The invention relates to the technical field of AC motors, in particular to a method and device for detecting faults in a pre-charging line of a motor controller. Background technique [0002] AC motors are widely used in all walks of life, but where there is only DC power supply, the motor controller needs to invert the DC power into AC power for the AC motor. see figure 1 The schematic diagram of the pre-charging circuit of the motor controller is shown. In the motor controller, a capacitor is usually required. When the DC power is connected to the motor controller, if the resistor R and the pre-charging relay K are not configured p , at the moment when the main relay K+ is turned on, due to the characteristics of the capacitor in the motor controller passing AC and blocking DC, the circuit is similar to a short circuit, which makes the current in the circuit very large, and it is easy to damage the capacitor and the main relay, resulting in the sys...

AI Technical Summary

Problems solved by technology

At this time, if the motor controller end plug is turned on again due to vibration or the load end circuit is artificially connected, the motor controller that is not "charged" is connected to the circuit at this time, and the instantaneous current is very large, which will easily cause damage to the motor controller and relay.

[0005] In addition, due to harsh environments such as severe vibrations, the insulation layer of the DC input cable of the motor controller often suffers from wear and tear, short circuits (or a certain contact resistance, similar to short circuits) or internal short circuits of the motor controller.

At this time, if the load is powered on according to the normal switching sequence, because the motor controller terminal is short-circuited, the U c 0 or always maintained at a voltage U d , and U d b , can never meet the power-on condition U c ≈ U b , see Figure 4 The voltage change curve under the short-circuit fault shown

In this case, the pre-charging work cannot be completed, the system cannot power on the motor controller, and there is always current in the abnormal pre-charging circuit, which poses a safety hazard

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