Why choose Type B sensor for leakage protection of European standard AC charger
1. Residual current is more complicated and prevention is more urgent
The residual current monitoring and popular application of residual current can be traced back to around 1990. The earliest type is TypeAC, and up to now, TypeB residual current monitoring has been adopted in many fields. Its inclusion relationship is shown in Figure 1. It is precisely because of the complexity of electrical equipment and the complexity of the circuit topology that the residual current monitoring has developed from the TypeAC type to the current TypeB type. The definition of Type B residual current includes Type AC, Type A and DC residual current, so Type B residual current detection is a relatively high requirement for residual current detection at present. Type B refers to smooth DC and intermittent DC on the basis of Type A leakage (AC, pulsating DC, half-wave AC).
2. The formation of smooth DC leakage
The existence of leakage current in the AC charging pile system includes AC, pulsating DC, pure DC and some high-frequency currents. There are several reasons why electric vehicles may be exposed to electricity when charging
(1) The danger of discontinuity of the protective ground wire.
(2) The insulation layer of the cable is damaged.
(3) Electric vehicles may come into contact with the active components of the car charger due to accidents, maintenance, etc.
(4) Humid and corrosive environment leads to electric leakage.
(5) Damaged components lead to leakage.
3. The necessity of DC leakage protection
For DC leakage protection, to understand why it is necessary to detect a smooth DC 6mA, it is necessary to proceed from standards and safety. The essence of the leakage current protection of the charging pile is introduced in the IEC61851 standard, namely "Protection against electric shock". Neither domestic safety standards nor foreign safety standards set smooth DC 6mA as the human body safety protection current, because such a small current would not cause harm to the human body. The reason for detecting it is also very simple. The excessive presence of smooth DC components will cause the A-type magnetic ring to saturate in advance, and eventually cause the A-type leakage protection to be inaccurate in the detection of AC leakage.
In the existing European standard pile market, for the upgraded leakage protection mode, the existing application processing methods generally have the following types:
1. Type B leakage protection scheme
Disadvantages: expensive, large size, low precision, poor anti-interference ability
2. TypeB leakage current sensor solution (TypeB-Sensor)
Product advantages of IVY Metering TypeB leakage current sensor: low cost, high precision, low temperature drift, anti-interference, small size, multiple installation methods (PCB/plug wire)
3. Type A+DC6mA
The first method is the wall-box solution led by Tesla. The equipment itself does not have a smooth DC leakage detection. In the case of upgrading the European standard IEC61851 safety regulations, there is no corresponding upgrade and integrated AC/DC Sensor inside the fuselage, which means Under the mandatory requirements of safety regulations, European users must hold Type B leak insurance before they can complete the construction of charging piles and connect them to the grid.
The second way is an integrated solution with relatively low price and cost. Since the national energy standard has not been upgraded, this solution is applied to export charging piles and domestic high-end car brands. Its features are also very prominent, using the characteristics of TypeB leakage current sensor (TypeB-Sensor) to detect AC and DC, and cooperate with the operation control of relay and MCU to complete the protection of the entire leakage current. The core is the detection and processing of the TypeB leakage current sensor (TypeB-Sensor).
Digital signal output
The advantage of protecting the leakage current is that it integrates the leakage protection requirements of IEC62752 (mode2) and IEC62955+TypeA (mode3), without calculation and processing, and protects the leakage current according to the high and low levels, plug and play. Engineers spend a lot of design energy and reduce the burden on MCU resources.