Hall current sensor CH701/CH701W is used in electric vehicle mode 2 charging devices

Charging electric vehicles is an essential part of the use of electric vehicles, and the speed of charging affects the travel patterns of electric vehicle users. According to the technical characteristics and usage properties of electric vehicle battery packs, there are different charging facilities, different charging modes, and different charging methods. There are three main methods for charging electric vehicles: one is public AC and DC charging piles; the second is private AC charging piles; and the third is portable chargers.

At present, when using public charging piles for charging, car owners need to face the trouble of finding charging piles, and the problem of being unable to charge after finding charging piles; and in the community, the property has very strict requirements on the installation of private charging piles, and often keeps many people out of the door. Obviously, the difficulty of charging is undoubtedly the biggest problem in car use. However, portable chargers have alleviated this problem to a certain extent at this stage. As long as you can find a household socket that meets the requirements, you can use it to charge electric vehicles. The portable charger that meets this demand is the charging device of electric vehicle mode 2-cable control and protection device.

1 Classification of electric vehicle charging modes

Electric vehicle charging equipment or equipment components provide dedicated functions for charging purposes to replenish electric energy to electric vehicles. The charging modes are divided into the following four categories:

(1) Charging Mode 1: When an electric vehicle is connected to the AC grid, a single-phase simple charging device is used, as shown in Figure 1. It does not have any protection function, and direct charging of electric vehicles using Mode 1 is prohibited.

(2) Charging mode 2: When the electric vehicle is connected to the AC power grid, a single-phase dedicated charging device is used, as shown in Figure 2. The device also has control guidance, residual current protection, overcurrent protection and switching functions.

(3) Charging mode 3: When the electric vehicle is connected to the AC power grid, a dedicated power supply device is used, as shown in Figure 3. It is equipped with a control guide device and has a residual current protection function.

(4) Charging Mode 4: A dedicated DC power supply device with control and guidance functions used when connecting an electric vehicle to an AC or DC power grid.

2 Cable Control and Protection Device (IC-CPD) The cable control and protection device (IC-CPD) is defined as: a group of components or elements that supply power to the electric vehicle in charging mode 2, including a function box, cable, power plug and vehicle connector, and is capable of performing control functions and safety functions, as shown in Figure 5.

Figure 5: IC-CPD components and functions

IC-CPD generally includes the following parts or components: power supply plug connected to fixed socket; function box containing control and protection features; cable between plug and function box; cable between function box and vehicle connector; vehicle connector for connecting electric vehicle. Among them, and are optional parts, and the other 3 are all required parts.

The independent functional box should contain three main functional modules: the residual current protection functional module ensures that at least a type A RCD with In≤30mA is provided when the basic protection and/or fault protection fails; the control and guidance functional module meets the control and guidance function requirements of Appendix A Electric Vehicle Mode 2 of GB/T18487.1-2015; the switch functional module can reliably connect or disconnect the current of one or several electrical circuits.

2.1 IC-CPD can be classified by structure into: IC-CPD with a function box independent of the plug and connector; IC-CPD with a function box integrated with the plug; modular IC-CPD. Among them, the function boxes of both types of IC-CPD include a residual current protection module, a control guidance module and a switch module. Modular IC-CPD is divided into two types: residual current protection and switch electrical appliances are integrated with the plug, and the control guidance controller is built into an independent function box and is between the plug and the vehicle connector; residual current protection and switch electrical appliances are integrated with the plug, and the control guidance controller is integrated with the vehicle connector.

2.2 IC-CPD use conditions IC-CPD is suitable for use in single-phase AC circuit voltage not exceeding 250V, maximum charging current not exceeding 16A, and the rated frequency is preferably 50Hz, 60Hz or 50/60Hz.

3 Current status and development of IC-CPD

Although charging mode 2 IC-CPD is a slow charging method with a long charging time, it does not require high charging infrastructure and has low construction costs. It can also make full use of low-power periods for charging to reduce charging costs. The more important advantage is that it can deeply charge the battery, improve battery charging and discharging efficiency, and extend battery life.

At present, IC-CPD is mostly a charging device delivered with the electric vehicle when it is purchased. Before the professional standard NB/T 42077-2016 was issued and implemented, IC-CPD on the market was basically tested for some items according to the requirements of car companies and with reference to relevant standards, or simply passed factory inspection and then flowed into the market, without considering all aspects of safety and conducting complete testing. In this way, IC-CPD is likely to cause personal injury, fire and other accidents during use, posing a great safety hazard. Therefore, it is urgent to carry out strict testing of IC-CPD products according to professional standards.

In July 2017, the biggest focus of the G20 Hamburg Summit, which just concluded, was the announcement of countries and timelines for the complete ban on the sale of fuel vehicles: France from 2040; Germany from 2030; Norway, where electric vehicles already account for 24%, from 2025; and the Netherlands from 2025. At the same time, the National Development and Reform Commission announced that it would prohibit the approval of new fuel vehicle projects and strictly control the existing fuel vehicle production capacity; it can be seen that the domestic and foreign governments attach increasing importance to new energy vehicles, mainly electric vehicles. Relevant data show and forecast that in 2016, my country's new energy vehicle ownership was 1.09 million; and from 2017 to 2020, my country's new energy vehicles will enter a stable growth stage, with a compound growth rate of about 40%, and then achieve an annual production of 2 million vehicles in 2020, and a national new energy vehicle ownership of 5 million vehicles in 2020.

Assuming that electric vehicle manufacturers maintain the policy of delivering one IC-CPD for each vehicle for a long time, the demand for testing and certification of IC-CPD charging device products will inevitably increase over a considerable period of time in the future.

4 Selection of current sensor in IC-CPD

Since IC-CPD is suitable for use in single-phase AC circuits with a voltage not exceeding 250V and a maximum charging current not exceeding 16A, the preferred rated frequency is 50Hz, 60Hz or 50/60Hz. An automotive-grade current sensor with an operating voltage greater than 250V and a rated current greater than 1.5 times the charging current is required to detect the current in the circuit. Since the overall structure of charging mode 2 is relatively small, a more compact Hall current sensor is required to achieve this function.

At present, Yirui Semiconductor (Shanghai) Co., Ltd. has a number of automotive-grade Hall current sensors that can meet the requirements. The following two series of products are recommended:

4.1 Detects DC or AC current from 5A to 70A.

Chip-type Hall current sensors are generally used to detect 5A to 50A DC or AC, such as

The CH701 current sensor IC is an economical and accurate solution for AC or DC current sensing in industrial, automotive, commercial and communication systems. The small package is ideal for space-constrained applications while saving costs due to reduced board area. Typical applications include motor control, load detection and management, switching power supplies and overcurrent fault protection.

CH701 can detect a peak current of 50A.

If you need to detect a larger current and a higher isolation voltage, you can choose a product with a larger current range, such as the 16-pin CH701W series, which has a current range of up to 70A and an insulation withstand voltage of up to 4800Vrms:

The CH701W series products have the following features:

Reinforced Isolation: 4800VRMS

AEC-Q100 qualified

Primary conductor resistance: 0.8 mΩ

Power supply: 3.3V or 5V

Multiple measurement currents: AC or DC ±5A, ±10A, ±20A, ±30A, ±40A, ±50A, ±60A, ±70A

Bandwidth: 120 kHz

Response time: 4us

Provide more flexible output mode

SOIC-16 package, saving PCB space

The chip has been calibrated for sensitivity and static (zero current) output voltage before leaving the factory to improve accuracy.

Chopper stabilization produces extremely stable quiescent output voltage

4.2 Detects DC or AC current from 50A to 200A.

Direct plug-in current sensor can be used

CH704 is an isolated integrated current sensing chip developed for high current detection applications. CH704 has a built-in primary conductor resistance of 0.1 mΩ, which effectively reduces chip heating and supports high current detection: ±50A, ±100A, ±150A, ±200A. It integrates a unique temperature compensation circuit to achieve good consistency of the chip in the full temperature range of -40 to 150 degrees. The chip has been calibrated for sensitivity and static (zero current) output voltage before leaving the factory, providing a typical accuracy of ±2% over the full temperature range.