Grounding technology was first applied to high-power systems (power systems, power transmission and transformation equipment, electrical equipment). For equipment and personal safety, the grounding wire was directly connected to the ground. Since the capacitance of the earth is very large, the potential of the earth can generally be regarded as zero potential. Later, the grounding technology was extended to the weak current system. For power electronics, the ground wire is directly connected to the ground or to a conductor as a reference potential. When the current passes through the reference potential, no voltage drop should be generated. However, due to unreasonable grounding, electromagnetic interference, such as common ground interference, ground loop interference, etc., is introduced, which causes the power electronic equipment to work abnormally. It can be seen that the grounding technology is one of the important contents of the electromagnetic compatibility technology of power electronic equipment.
Power electronics are typically grounded for several purposes:
The safety ground will connect the casing to the ground. First, it prevents the accumulation of electric charge on the casing, which causes electrostatic discharge and endangers equipment and personal safety. Second, when the insulation of the equipment is damaged and the casing is charged, the protection of the power supply is prompted to cut off the power supply to protect the safety of the workers.
Lightning protection grounding
When a power electronic device encounters a lightning strike, whether it is a direct lightning strike or an induced lightning strike, the power electronic device will be greatly harmed. A lightning rod is installed to prevent lightning strikes to prevent equipment and personal safety when lightning strikes.
The working ground is a reference potential provided for the normal operation of the circuit. The reference potential can be set to a certain point, a certain section or a block in the circuit system. When the reference potential is not connected to the ground, it is regarded as a relative zero potential. This relative zero potential changes with the change of the external electromagnetic field, which leads to instability of the circuit system. When the reference potential is connected to the ground, the reference potential is regarded as the zero potential of the earth, and does not change with the change of the external electromagnetic field. However, incorrect working grounding will increase interference. For example, common ground interference, ground loop interference, etc.
In order to prevent various circuits from interfering with each other during operation, they can work in compatibility with each other. According to the nature of the circuit, the working ground is divided into different types, such as DC ground, AC ground, digital ground, analog ground, signal ground, power ground, power ground, and the like. The different groundings described above should be set separately.