TypeB leakage current sensor charging mode full coverage

Charging is safer, electricity is more accurate, and design is more efficient

1. Electric vehicles are developing rapidly, and the demand for charging piles is strong.

International standard "IEC62752-2016 In- cable control and protection device for mode 2 charging of electric road vehicles (IC-CPD)" was officially released in 2016. The function and role of IC-CPD are specified in the standard. Among them, TypeB residual current detection becomes an important function. The RCPD (Residual Current Protection Device) series of residual current sensors launched by RichSens fully meet this standard.

The second charging mode (Mode2) is gradually popularized. IC-CPD has become a standard accessory in electric vehicles. The popularization of IC-CPD can greatly facilitate charging at any time, including home charging and out-of-home charging. As the second charging mode (Mode2), it is also accepted by more users. As the standard is upgraded and unified, more OEMs will also choose IC-CPD as a standard accessory.

In 2017, the global sales of new energy electric passenger vehicles were 1,197,100, a year-on-year increase of 67%, of which overseas sales were 629,700 (a year-on-year increase of 51.78%) and China's sales were 567,400 (a year-on-year increase of 88.1%). Most of them are based on pure electric vehicles.

2. Residual current is more complicated and prevention is more urgent.

Residual current monitoring and residual current popularization application can be traced back to around 1990. It was TypeAC at the earliest, and TypeB residual current monitoring has been adopted in many fields. The containment relationship is shown in Figure 2. It is precisely because of the complexity of the electrical equipment and the complexity of the circuit topology that the residual current monitoring has evolved from the TypeAC type to the current TypeB type. The TypeB residual current definition includes TypeAC, TypeA and DC residual current, so TypeB residual current detection is a relatively high requirement for residual current detection.

TypeB refers to the smooth DC and intermittent DC on the basis of Type A leakage (AC, pulsating DC, half-wave AC).

Figure 1 Schematic diagram of different power consumption networks and residual current

(from "ABB Technical Information")

In the field of electric vehicles, The internal charging topology is more complicated, and the electric vehicle power battery is a DC power supply system. Therefore, the current component is more complicated, including AC current and pulsating current, especially in this special application scenario. Based on this, the residual current is also more complicated. The power battery of an electric vehicle is equivalent to a very large capacitive load. Therefore, when a leakage occurs, the TypeB DC residual current will often appear in the circuit topology of 4, 5, and 6 in Figure 2.

In order to protect the safety of life and property, it is recommended to install a Type B leakage current sensor or Type B leakage circuit breaker with higher protection level on the charging pile. There are two conventional methods to prevent residual current:

1) Add a leakage circuit breaker (RCD)

In household and industrial fields, leakage switches are generally installed, such as TypeA leakage switches in gas water heaters , Leakage circuit breakers used in the industrial field. Especially in the field of charging piles, since the standard requires the use of TypeA or TypeB leakage circuit breakers, the scheme of adding leakage circuit breakers in the circuit system is generally adopted. In 2018, many companies such as China Southern Power Grid also promoted Type B leakage current sensors in the field of charging piles.

2) Add Type B current sensor

For example, residual current sensors are commonly used in photovoltaic inverters for leakage protection. Currently in IC-This scheme is commonly used in CPD.

3. Type B leakage current sensor application in different charging modes

Mode two

Figure 2 IC-CPD Schematic diagram of leakage sensor application

(excerpted from RichSensor technical data of Yichang Rui Magnetic Technology Co., Ltd.)

Among them, two 7mm² copper wires passing through the RCPD12A leakage current sensor, the RMS current is above 40A, charging The active power is higher than 6.6kW. The electrical clearance and creepage distance are above 4mm, which meets the requirements of NB/T 42077 and IEC-62752. The layout of the bureau is shown in the figure below.

Figure 3 6.6kW IC-CPD in the leakage current sensor design

(taken from a design application)

For ICs below 3.5kW- For CPD, it is recommended to use RCPD100A. The zero point stability is excellent. The zero point temperature drift is less than 1.5mA at -40℃~85℃. The zero point stability enables the subsequent processing circuit and single-chip microcomputer to deal with the A type action point, and the DC smooth action point is more accurate.

Mode 3

Mode 3 has a large charging current. Generally, single-phase or three-phase current lines are used to directly pass through the sensor. It is not recommended to introduce AC current to the AC control board.

Figure 4 RCM01SL is used in the charging pile

Mode 4

Mode 4 charging current is larger, B type circuit breaker is recommended, At the same time, it satisfies the overcurrent detection function and the leakage current detection function. Due to the magnetic isolation device, it has a good shielding effect against the overcurrent of 6 times the working current.

Figure 5 RCBD125 applied to 125A leakage circuit breaker

can also use RCPD25I, aperture 25mm, panel mounting. The internal design of high-efficiency magnetic isolation, among which the Trip output meets the B-type leakage standard, can be operated intelligently, and has a CAN output to output various states in real time.

Figure 6 RCPD25A, used in 50kW charging pile

Yichang Rui Magnetic Technology Co., Ltd. (RichSensor) has many years of experience in fluxgate current sensor research and development, and has launched ICs -CPD leakage current sensor RCPD (Residual Current Protection Device), TypeB type circuit breaker current sensor, electric vehicle power monitoring sensor FCC300. Among them, the RCPD series residual current sensor can be used in IC-CPD to realize the AC and DC TypeB residual current detection function and meet the requirements of the new standard.